[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
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#include "audit.h"
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#include <linux/inotify.h>
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#include <linux/namei.h>
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#include <linux/mount.h>
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struct audit_tree;
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struct audit_chunk;
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struct audit_tree {
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atomic_t count;
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int goner;
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struct audit_chunk *root;
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struct list_head chunks;
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struct list_head rules;
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struct list_head list;
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struct list_head same_root;
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struct rcu_head head;
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char pathname[];
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};
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struct audit_chunk {
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struct list_head hash;
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struct inotify_watch watch;
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struct list_head trees; /* with root here */
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int dead;
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int count;
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Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
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atomic_long_t refs;
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[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
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struct rcu_head head;
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struct node {
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struct list_head list;
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struct audit_tree *owner;
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unsigned index; /* index; upper bit indicates 'will prune' */
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} owners[];
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};
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static LIST_HEAD(tree_list);
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static LIST_HEAD(prune_list);
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/*
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* One struct chunk is attached to each inode of interest.
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* We replace struct chunk on tagging/untagging.
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* Rules have pointer to struct audit_tree.
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* Rules have struct list_head rlist forming a list of rules over
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* the same tree.
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* References to struct chunk are collected at audit_inode{,_child}()
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* time and used in AUDIT_TREE rule matching.
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* These references are dropped at the same time we are calling
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* audit_free_names(), etc.
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*
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* Cyclic lists galore:
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* tree.chunks anchors chunk.owners[].list hash_lock
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* tree.rules anchors rule.rlist audit_filter_mutex
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* chunk.trees anchors tree.same_root hash_lock
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* chunk.hash is a hash with middle bits of watch.inode as
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* a hash function. RCU, hash_lock
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*
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* tree is refcounted; one reference for "some rules on rules_list refer to
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* it", one for each chunk with pointer to it.
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*
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Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
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* chunk is refcounted by embedded inotify_watch + .refs (non-zero refcount
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* of watch contributes 1 to .refs).
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
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*
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* node.index allows to get from node.list to containing chunk.
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* MSB of that sucker is stolen to mark taggings that we might have to
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* revert - several operations have very unpleasant cleanup logics and
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* that makes a difference. Some.
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*/
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static struct inotify_handle *rtree_ih;
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static struct audit_tree *alloc_tree(const char *s)
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{
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struct audit_tree *tree;
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tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
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if (tree) {
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atomic_set(&tree->count, 1);
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tree->goner = 0;
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INIT_LIST_HEAD(&tree->chunks);
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INIT_LIST_HEAD(&tree->rules);
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INIT_LIST_HEAD(&tree->list);
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INIT_LIST_HEAD(&tree->same_root);
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tree->root = NULL;
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strcpy(tree->pathname, s);
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}
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return tree;
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}
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static inline void get_tree(struct audit_tree *tree)
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{
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atomic_inc(&tree->count);
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}
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static void __put_tree(struct rcu_head *rcu)
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{
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struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
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kfree(tree);
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}
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static inline void put_tree(struct audit_tree *tree)
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{
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if (atomic_dec_and_test(&tree->count))
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call_rcu(&tree->head, __put_tree);
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}
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/* to avoid bringing the entire thing in audit.h */
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const char *audit_tree_path(struct audit_tree *tree)
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{
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return tree->pathname;
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}
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static struct audit_chunk *alloc_chunk(int count)
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{
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struct audit_chunk *chunk;
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size_t size;
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int i;
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size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
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chunk = kzalloc(size, GFP_KERNEL);
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if (!chunk)
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return NULL;
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INIT_LIST_HEAD(&chunk->hash);
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INIT_LIST_HEAD(&chunk->trees);
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chunk->count = count;
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
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atomic_long_set(&chunk->refs, 1);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
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for (i = 0; i < count; i++) {
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INIT_LIST_HEAD(&chunk->owners[i].list);
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chunk->owners[i].index = i;
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}
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inotify_init_watch(&chunk->watch);
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return chunk;
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}
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|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
static void free_chunk(struct audit_chunk *chunk)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
{
|
|
|
|
int i;
|
|
|
|
|
|
|
|
for (i = 0; i < chunk->count; i++) {
|
|
|
|
if (chunk->owners[i].owner)
|
|
|
|
put_tree(chunk->owners[i].owner);
|
|
|
|
}
|
|
|
|
kfree(chunk);
|
|
|
|
}
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
void audit_put_chunk(struct audit_chunk *chunk)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
{
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
if (atomic_long_dec_and_test(&chunk->refs))
|
|
|
|
free_chunk(chunk);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
static void __put_chunk(struct rcu_head *rcu)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
{
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
|
|
|
|
audit_put_chunk(chunk);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
enum {HASH_SIZE = 128};
|
|
|
|
static struct list_head chunk_hash_heads[HASH_SIZE];
|
|
|
|
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
|
|
|
|
|
|
|
|
static inline struct list_head *chunk_hash(const struct inode *inode)
|
|
|
|
{
|
|
|
|
unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
|
|
|
|
return chunk_hash_heads + n % HASH_SIZE;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* hash_lock is held by caller */
|
|
|
|
static void insert_hash(struct audit_chunk *chunk)
|
|
|
|
{
|
|
|
|
struct list_head *list = chunk_hash(chunk->watch.inode);
|
|
|
|
list_add_rcu(&chunk->hash, list);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* called under rcu_read_lock */
|
|
|
|
struct audit_chunk *audit_tree_lookup(const struct inode *inode)
|
|
|
|
{
|
|
|
|
struct list_head *list = chunk_hash(inode);
|
2008-05-14 17:10:12 -07:00
|
|
|
struct audit_chunk *p;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
|
2008-05-14 17:10:12 -07:00
|
|
|
list_for_each_entry_rcu(p, list, hash) {
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (p->watch.inode == inode) {
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
atomic_long_inc(&p->refs);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
return p;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
int n;
|
|
|
|
for (n = 0; n < chunk->count; n++)
|
|
|
|
if (chunk->owners[n].owner == tree)
|
|
|
|
return 1;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* tagging and untagging inodes with trees */
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
static struct audit_chunk *find_chunk(struct node *p)
|
|
|
|
{
|
|
|
|
int index = p->index & ~(1U<<31);
|
|
|
|
p -= index;
|
|
|
|
return container_of(p, struct audit_chunk, owners[0]);
|
|
|
|
}
|
|
|
|
|
|
|
|
static void untag_chunk(struct node *p)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
{
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
struct audit_chunk *chunk = find_chunk(p);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
struct audit_chunk *new;
|
|
|
|
struct audit_tree *owner;
|
|
|
|
int size = chunk->count - 1;
|
|
|
|
int i, j;
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
if (!pin_inotify_watch(&chunk->watch)) {
|
|
|
|
/*
|
|
|
|
* Filesystem is shutting down; all watches are getting
|
|
|
|
* evicted, just take it off the node list for this
|
|
|
|
* tree and let the eviction logics take care of the
|
|
|
|
* rest.
|
|
|
|
*/
|
|
|
|
owner = p->owner;
|
|
|
|
if (owner->root == chunk) {
|
|
|
|
list_del_init(&owner->same_root);
|
|
|
|
owner->root = NULL;
|
|
|
|
}
|
|
|
|
list_del_init(&p->list);
|
|
|
|
p->owner = NULL;
|
|
|
|
put_tree(owner);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* pin_inotify_watch() succeeded, so the watch won't go away
|
|
|
|
* from under us.
|
|
|
|
*/
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
mutex_lock(&chunk->watch.inode->inotify_mutex);
|
|
|
|
if (chunk->dead) {
|
|
|
|
mutex_unlock(&chunk->watch.inode->inotify_mutex);
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
goto out;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
owner = p->owner;
|
|
|
|
|
|
|
|
if (!size) {
|
|
|
|
chunk->dead = 1;
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_del_init(&chunk->trees);
|
|
|
|
if (owner->root == chunk)
|
|
|
|
owner->root = NULL;
|
|
|
|
list_del_init(&p->list);
|
|
|
|
list_del_rcu(&chunk->hash);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
inotify_evict_watch(&chunk->watch);
|
|
|
|
mutex_unlock(&chunk->watch.inode->inotify_mutex);
|
|
|
|
put_inotify_watch(&chunk->watch);
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
goto out;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
new = alloc_chunk(size);
|
|
|
|
if (!new)
|
|
|
|
goto Fallback;
|
|
|
|
if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
|
|
|
|
free_chunk(new);
|
|
|
|
goto Fallback;
|
|
|
|
}
|
|
|
|
|
|
|
|
chunk->dead = 1;
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_replace_init(&chunk->trees, &new->trees);
|
|
|
|
if (owner->root == chunk) {
|
|
|
|
list_del_init(&owner->same_root);
|
|
|
|
owner->root = NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
for (i = j = 0; i < size; i++, j++) {
|
|
|
|
struct audit_tree *s;
|
|
|
|
if (&chunk->owners[j] == p) {
|
|
|
|
list_del_init(&p->list);
|
|
|
|
i--;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
s = chunk->owners[j].owner;
|
|
|
|
new->owners[i].owner = s;
|
|
|
|
new->owners[i].index = chunk->owners[j].index - j + i;
|
|
|
|
if (!s) /* result of earlier fallback */
|
|
|
|
continue;
|
|
|
|
get_tree(s);
|
|
|
|
list_replace_init(&chunk->owners[i].list, &new->owners[j].list);
|
|
|
|
}
|
|
|
|
|
|
|
|
list_replace_rcu(&chunk->hash, &new->hash);
|
|
|
|
list_for_each_entry(owner, &new->trees, same_root)
|
|
|
|
owner->root = new;
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
inotify_evict_watch(&chunk->watch);
|
|
|
|
mutex_unlock(&chunk->watch.inode->inotify_mutex);
|
|
|
|
put_inotify_watch(&chunk->watch);
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
goto out;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
|
|
|
|
Fallback:
|
|
|
|
// do the best we can
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
if (owner->root == chunk) {
|
|
|
|
list_del_init(&owner->same_root);
|
|
|
|
owner->root = NULL;
|
|
|
|
}
|
|
|
|
list_del_init(&p->list);
|
|
|
|
p->owner = NULL;
|
|
|
|
put_tree(owner);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
mutex_unlock(&chunk->watch.inode->inotify_mutex);
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
out:
|
|
|
|
unpin_inotify_watch(&chunk->watch);
|
|
|
|
spin_lock(&hash_lock);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
static int create_chunk(struct inode *inode, struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
struct audit_chunk *chunk = alloc_chunk(1);
|
|
|
|
if (!chunk)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
|
|
|
|
free_chunk(chunk);
|
|
|
|
return -ENOSPC;
|
|
|
|
}
|
|
|
|
|
|
|
|
mutex_lock(&inode->inotify_mutex);
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
if (tree->goner) {
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
chunk->dead = 1;
|
|
|
|
inotify_evict_watch(&chunk->watch);
|
|
|
|
mutex_unlock(&inode->inotify_mutex);
|
|
|
|
put_inotify_watch(&chunk->watch);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
chunk->owners[0].index = (1U << 31);
|
|
|
|
chunk->owners[0].owner = tree;
|
|
|
|
get_tree(tree);
|
|
|
|
list_add(&chunk->owners[0].list, &tree->chunks);
|
|
|
|
if (!tree->root) {
|
|
|
|
tree->root = chunk;
|
|
|
|
list_add(&tree->same_root, &chunk->trees);
|
|
|
|
}
|
|
|
|
insert_hash(chunk);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
mutex_unlock(&inode->inotify_mutex);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* the first tagged inode becomes root of tree */
|
|
|
|
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
struct inotify_watch *watch;
|
|
|
|
struct audit_tree *owner;
|
|
|
|
struct audit_chunk *chunk, *old;
|
|
|
|
struct node *p;
|
|
|
|
int n;
|
|
|
|
|
|
|
|
if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
|
|
|
|
return create_chunk(inode, tree);
|
|
|
|
|
|
|
|
old = container_of(watch, struct audit_chunk, watch);
|
|
|
|
|
|
|
|
/* are we already there? */
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
for (n = 0; n < old->count; n++) {
|
|
|
|
if (old->owners[n].owner == tree) {
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
put_inotify_watch(watch);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
|
|
|
|
chunk = alloc_chunk(old->count + 1);
|
|
|
|
if (!chunk)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
|
|
|
mutex_lock(&inode->inotify_mutex);
|
|
|
|
if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
|
|
|
|
mutex_unlock(&inode->inotify_mutex);
|
2009-01-13 15:32:40 -07:00
|
|
|
put_inotify_watch(&old->watch);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
free_chunk(chunk);
|
|
|
|
return -ENOSPC;
|
|
|
|
}
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
if (tree->goner) {
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
chunk->dead = 1;
|
|
|
|
inotify_evict_watch(&chunk->watch);
|
|
|
|
mutex_unlock(&inode->inotify_mutex);
|
2009-01-13 15:32:40 -07:00
|
|
|
put_inotify_watch(&old->watch);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
put_inotify_watch(&chunk->watch);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
list_replace_init(&old->trees, &chunk->trees);
|
|
|
|
for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
|
|
|
|
struct audit_tree *s = old->owners[n].owner;
|
|
|
|
p->owner = s;
|
|
|
|
p->index = old->owners[n].index;
|
|
|
|
if (!s) /* result of fallback in untag */
|
|
|
|
continue;
|
|
|
|
get_tree(s);
|
|
|
|
list_replace_init(&old->owners[n].list, &p->list);
|
|
|
|
}
|
|
|
|
p->index = (chunk->count - 1) | (1U<<31);
|
|
|
|
p->owner = tree;
|
|
|
|
get_tree(tree);
|
|
|
|
list_add(&p->list, &tree->chunks);
|
|
|
|
list_replace_rcu(&old->hash, &chunk->hash);
|
|
|
|
list_for_each_entry(owner, &chunk->trees, same_root)
|
|
|
|
owner->root = chunk;
|
|
|
|
old->dead = 1;
|
|
|
|
if (!tree->root) {
|
|
|
|
tree->root = chunk;
|
|
|
|
list_add(&tree->same_root, &chunk->trees);
|
|
|
|
}
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
inotify_evict_watch(&old->watch);
|
|
|
|
mutex_unlock(&inode->inotify_mutex);
|
|
|
|
put_inotify_watch(&old->watch);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void kill_rules(struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
struct audit_krule *rule, *next;
|
|
|
|
struct audit_entry *entry;
|
|
|
|
struct audit_buffer *ab;
|
|
|
|
|
|
|
|
list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
|
|
|
|
entry = container_of(rule, struct audit_entry, rule);
|
|
|
|
|
|
|
|
list_del_init(&rule->rlist);
|
|
|
|
if (rule->tree) {
|
|
|
|
/* not a half-baked one */
|
|
|
|
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
|
|
|
|
audit_log_format(ab, "op=remove rule dir=");
|
|
|
|
audit_log_untrustedstring(ab, rule->tree->pathname);
|
|
|
|
if (rule->filterkey) {
|
|
|
|
audit_log_format(ab, " key=");
|
|
|
|
audit_log_untrustedstring(ab, rule->filterkey);
|
|
|
|
} else
|
|
|
|
audit_log_format(ab, " key=(null)");
|
|
|
|
audit_log_format(ab, " list=%d res=1", rule->listnr);
|
|
|
|
audit_log_end(ab);
|
|
|
|
rule->tree = NULL;
|
|
|
|
list_del_rcu(&entry->list);
|
2008-12-14 23:17:50 -07:00
|
|
|
list_del(&entry->rule.list);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
call_rcu(&entry->rcu, audit_free_rule_rcu);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* finish killing struct audit_tree
|
|
|
|
*/
|
|
|
|
static void prune_one(struct audit_tree *victim)
|
|
|
|
{
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
while (!list_empty(&victim->chunks)) {
|
|
|
|
struct node *p;
|
|
|
|
|
|
|
|
p = list_entry(victim->chunks.next, struct node, list);
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
untag_chunk(p);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
put_tree(victim);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* trim the uncommitted chunks from tree */
|
|
|
|
|
|
|
|
static void trim_marked(struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
struct list_head *p, *q;
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
if (tree->goner) {
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
/* reorder */
|
|
|
|
for (p = tree->chunks.next; p != &tree->chunks; p = q) {
|
|
|
|
struct node *node = list_entry(p, struct node, list);
|
|
|
|
q = p->next;
|
|
|
|
if (node->index & (1U<<31)) {
|
|
|
|
list_del_init(p);
|
|
|
|
list_add(p, &tree->chunks);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
while (!list_empty(&tree->chunks)) {
|
|
|
|
struct node *node;
|
|
|
|
|
|
|
|
node = list_entry(tree->chunks.next, struct node, list);
|
|
|
|
|
|
|
|
/* have we run out of marked? */
|
|
|
|
if (!(node->index & (1U<<31)))
|
|
|
|
break;
|
|
|
|
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
untag_chunk(node);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
if (!tree->root && !tree->goner) {
|
|
|
|
tree->goner = 1;
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
kill_rules(tree);
|
|
|
|
list_del_init(&tree->list);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
prune_one(tree);
|
|
|
|
} else {
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/* called with audit_filter_mutex */
|
|
|
|
int audit_remove_tree_rule(struct audit_krule *rule)
|
|
|
|
{
|
|
|
|
struct audit_tree *tree;
|
|
|
|
tree = rule->tree;
|
|
|
|
if (tree) {
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_del_init(&rule->rlist);
|
|
|
|
if (list_empty(&tree->rules) && !tree->goner) {
|
|
|
|
tree->root = NULL;
|
|
|
|
list_del_init(&tree->same_root);
|
|
|
|
tree->goner = 1;
|
|
|
|
list_move(&tree->list, &prune_list);
|
|
|
|
rule->tree = NULL;
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
audit_schedule_prune();
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
rule->tree = NULL;
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
return 1;
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
void audit_trim_trees(void)
|
|
|
|
{
|
|
|
|
struct list_head cursor;
|
|
|
|
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
list_add(&cursor, &tree_list);
|
|
|
|
while (cursor.next != &tree_list) {
|
|
|
|
struct audit_tree *tree;
|
2008-08-01 22:06:21 -07:00
|
|
|
struct path path;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
struct vfsmount *root_mnt;
|
|
|
|
struct node *node;
|
|
|
|
struct list_head list;
|
|
|
|
int err;
|
|
|
|
|
|
|
|
tree = container_of(cursor.next, struct audit_tree, list);
|
|
|
|
get_tree(tree);
|
|
|
|
list_del(&cursor);
|
|
|
|
list_add(&cursor, &tree->list);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
err = kern_path(tree->pathname, 0, &path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (err)
|
|
|
|
goto skip_it;
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
root_mnt = collect_mounts(path.mnt, path.dentry);
|
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (!root_mnt)
|
|
|
|
goto skip_it;
|
|
|
|
|
|
|
|
list_add_tail(&list, &root_mnt->mnt_list);
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_for_each_entry(node, &tree->chunks, list) {
|
|
|
|
struct audit_chunk *chunk = find_chunk(node);
|
|
|
|
struct inode *inode = chunk->watch.inode;
|
|
|
|
struct vfsmount *mnt;
|
|
|
|
node->index |= 1U<<31;
|
|
|
|
list_for_each_entry(mnt, &list, mnt_list) {
|
|
|
|
if (mnt->mnt_root->d_inode == inode) {
|
|
|
|
node->index &= ~(1U<<31);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
trim_marked(tree);
|
|
|
|
put_tree(tree);
|
|
|
|
list_del_init(&list);
|
|
|
|
drop_collected_mounts(root_mnt);
|
|
|
|
skip_it:
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
list_del(&cursor);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
|
|
|
|
static int is_under(struct vfsmount *mnt, struct dentry *dentry,
|
2008-08-01 22:06:21 -07:00
|
|
|
struct path *path)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
{
|
2008-08-01 22:06:21 -07:00
|
|
|
if (mnt != path->mnt) {
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
for (;;) {
|
|
|
|
if (mnt->mnt_parent == mnt)
|
|
|
|
return 0;
|
2008-08-01 22:06:21 -07:00
|
|
|
if (mnt->mnt_parent == path->mnt)
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
break;
|
|
|
|
mnt = mnt->mnt_parent;
|
|
|
|
}
|
|
|
|
dentry = mnt->mnt_mountpoint;
|
|
|
|
}
|
2008-08-01 22:06:21 -07:00
|
|
|
return is_subdir(dentry, path->dentry);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
|
|
|
|
{
|
|
|
|
|
|
|
|
if (pathname[0] != '/' ||
|
|
|
|
rule->listnr != AUDIT_FILTER_EXIT ||
|
2008-12-16 03:59:26 -07:00
|
|
|
op != Audit_equal ||
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
rule->inode_f || rule->watch || rule->tree)
|
|
|
|
return -EINVAL;
|
|
|
|
rule->tree = alloc_tree(pathname);
|
|
|
|
if (!rule->tree)
|
|
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
void audit_put_tree(struct audit_tree *tree)
|
|
|
|
{
|
|
|
|
put_tree(tree);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* called with audit_filter_mutex */
|
|
|
|
int audit_add_tree_rule(struct audit_krule *rule)
|
|
|
|
{
|
|
|
|
struct audit_tree *seed = rule->tree, *tree;
|
2008-08-01 22:06:21 -07:00
|
|
|
struct path path;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
struct vfsmount *mnt, *p;
|
|
|
|
struct list_head list;
|
|
|
|
int err;
|
|
|
|
|
|
|
|
list_for_each_entry(tree, &tree_list, list) {
|
|
|
|
if (!strcmp(seed->pathname, tree->pathname)) {
|
|
|
|
put_tree(seed);
|
|
|
|
rule->tree = tree;
|
|
|
|
list_add(&rule->rlist, &tree->rules);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
tree = seed;
|
|
|
|
list_add(&tree->list, &tree_list);
|
|
|
|
list_add(&rule->rlist, &tree->rules);
|
|
|
|
/* do not set rule->tree yet */
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
err = kern_path(tree->pathname, 0, &path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (err)
|
|
|
|
goto Err;
|
2008-08-01 22:06:21 -07:00
|
|
|
mnt = collect_mounts(path.mnt, path.dentry);
|
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (!mnt) {
|
|
|
|
err = -ENOMEM;
|
|
|
|
goto Err;
|
|
|
|
}
|
|
|
|
list_add_tail(&list, &mnt->mnt_list);
|
|
|
|
|
|
|
|
get_tree(tree);
|
|
|
|
list_for_each_entry(p, &list, mnt_list) {
|
|
|
|
err = tag_chunk(p->mnt_root->d_inode, tree);
|
|
|
|
if (err)
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
list_del(&list);
|
|
|
|
drop_collected_mounts(mnt);
|
|
|
|
|
|
|
|
if (!err) {
|
|
|
|
struct node *node;
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_for_each_entry(node, &tree->chunks, list)
|
|
|
|
node->index &= ~(1U<<31);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
} else {
|
|
|
|
trim_marked(tree);
|
|
|
|
goto Err;
|
|
|
|
}
|
|
|
|
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
if (list_empty(&rule->rlist)) {
|
|
|
|
put_tree(tree);
|
|
|
|
return -ENOENT;
|
|
|
|
}
|
|
|
|
rule->tree = tree;
|
|
|
|
put_tree(tree);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
Err:
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
list_del_init(&tree->list);
|
|
|
|
list_del_init(&tree->rules);
|
|
|
|
put_tree(tree);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
int audit_tag_tree(char *old, char *new)
|
|
|
|
{
|
|
|
|
struct list_head cursor, barrier;
|
|
|
|
int failed = 0;
|
2008-08-01 22:06:21 -07:00
|
|
|
struct path path;
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
struct vfsmount *tagged;
|
|
|
|
struct list_head list;
|
|
|
|
struct vfsmount *mnt;
|
|
|
|
struct dentry *dentry;
|
|
|
|
int err;
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
err = kern_path(new, 0, &path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (err)
|
|
|
|
return err;
|
2008-08-01 22:06:21 -07:00
|
|
|
tagged = collect_mounts(path.mnt, path.dentry);
|
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (!tagged)
|
|
|
|
return -ENOMEM;
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
err = kern_path(old, 0, &path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (err) {
|
|
|
|
drop_collected_mounts(tagged);
|
|
|
|
return err;
|
|
|
|
}
|
2008-08-01 22:06:21 -07:00
|
|
|
mnt = mntget(path.mnt);
|
|
|
|
dentry = dget(path.dentry);
|
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
|
|
|
|
list_add_tail(&list, &tagged->mnt_list);
|
|
|
|
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
list_add(&barrier, &tree_list);
|
|
|
|
list_add(&cursor, &barrier);
|
|
|
|
|
|
|
|
while (cursor.next != &tree_list) {
|
|
|
|
struct audit_tree *tree;
|
|
|
|
struct vfsmount *p;
|
|
|
|
|
|
|
|
tree = container_of(cursor.next, struct audit_tree, list);
|
|
|
|
get_tree(tree);
|
|
|
|
list_del(&cursor);
|
|
|
|
list_add(&cursor, &tree->list);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
|
2008-08-01 22:06:21 -07:00
|
|
|
err = kern_path(tree->pathname, 0, &path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
if (err) {
|
|
|
|
put_tree(tree);
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
spin_lock(&vfsmount_lock);
|
2008-08-01 22:06:21 -07:00
|
|
|
if (!is_under(mnt, dentry, &path)) {
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
spin_unlock(&vfsmount_lock);
|
2008-08-01 22:06:21 -07:00
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
put_tree(tree);
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
spin_unlock(&vfsmount_lock);
|
2008-08-01 22:06:21 -07:00
|
|
|
path_put(&path);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
|
|
|
|
list_for_each_entry(p, &list, mnt_list) {
|
|
|
|
failed = tag_chunk(p->mnt_root->d_inode, tree);
|
|
|
|
if (failed)
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (failed) {
|
|
|
|
put_tree(tree);
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
if (!tree->goner) {
|
|
|
|
list_del(&tree->list);
|
|
|
|
list_add(&tree->list, &tree_list);
|
|
|
|
}
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
put_tree(tree);
|
|
|
|
}
|
|
|
|
|
|
|
|
while (barrier.prev != &tree_list) {
|
|
|
|
struct audit_tree *tree;
|
|
|
|
|
|
|
|
tree = container_of(barrier.prev, struct audit_tree, list);
|
|
|
|
get_tree(tree);
|
|
|
|
list_del(&tree->list);
|
|
|
|
list_add(&tree->list, &barrier);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
|
|
|
|
if (!failed) {
|
|
|
|
struct node *node;
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
list_for_each_entry(node, &tree->chunks, list)
|
|
|
|
node->index &= ~(1U<<31);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
} else {
|
|
|
|
trim_marked(tree);
|
|
|
|
}
|
|
|
|
|
|
|
|
put_tree(tree);
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
list_del(&barrier);
|
|
|
|
list_del(&cursor);
|
|
|
|
list_del(&list);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
dput(dentry);
|
|
|
|
mntput(mnt);
|
|
|
|
drop_collected_mounts(tagged);
|
|
|
|
return failed;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* That gets run when evict_chunk() ends up needing to kill audit_tree.
|
|
|
|
* Runs from a separate thread, with audit_cmd_mutex held.
|
|
|
|
*/
|
|
|
|
void audit_prune_trees(void)
|
|
|
|
{
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
|
|
|
|
while (!list_empty(&prune_list)) {
|
|
|
|
struct audit_tree *victim;
|
|
|
|
|
|
|
|
victim = list_entry(prune_list.next, struct audit_tree, list);
|
|
|
|
list_del_init(&victim->list);
|
|
|
|
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
|
|
|
|
prune_one(victim);
|
|
|
|
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Here comes the stuff asynchronous to auditctl operations
|
|
|
|
*/
|
|
|
|
|
|
|
|
/* inode->inotify_mutex is locked */
|
|
|
|
static void evict_chunk(struct audit_chunk *chunk)
|
|
|
|
{
|
|
|
|
struct audit_tree *owner;
|
|
|
|
int n;
|
|
|
|
|
|
|
|
if (chunk->dead)
|
|
|
|
return;
|
|
|
|
|
|
|
|
chunk->dead = 1;
|
|
|
|
mutex_lock(&audit_filter_mutex);
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
while (!list_empty(&chunk->trees)) {
|
|
|
|
owner = list_entry(chunk->trees.next,
|
|
|
|
struct audit_tree, same_root);
|
|
|
|
owner->goner = 1;
|
|
|
|
owner->root = NULL;
|
|
|
|
list_del_init(&owner->same_root);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
kill_rules(owner);
|
|
|
|
list_move(&owner->list, &prune_list);
|
|
|
|
audit_schedule_prune();
|
|
|
|
spin_lock(&hash_lock);
|
|
|
|
}
|
|
|
|
list_del_rcu(&chunk->hash);
|
|
|
|
for (n = 0; n < chunk->count; n++)
|
|
|
|
list_del_init(&chunk->owners[n].list);
|
|
|
|
spin_unlock(&hash_lock);
|
|
|
|
mutex_unlock(&audit_filter_mutex);
|
|
|
|
}
|
|
|
|
|
|
|
|
static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
|
|
|
|
u32 cookie, const char *dname, struct inode *inode)
|
|
|
|
{
|
|
|
|
struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
|
|
|
|
|
|
|
|
if (mask & IN_IGNORED) {
|
|
|
|
evict_chunk(chunk);
|
|
|
|
put_inotify_watch(watch);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
static void destroy_watch(struct inotify_watch *watch)
|
|
|
|
{
|
|
|
|
struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
|
Fix inotify watch removal/umount races
Inotify watch removals suck violently.
To kick the watch out we need (in this order) inode->inotify_mutex and
ih->mutex. That's fine if we have a hold on inode; however, for all
other cases we need to make damn sure we don't race with umount. We can
*NOT* just grab a reference to a watch - inotify_unmount_inodes() will
happily sail past it and we'll end with reference to inode potentially
outliving its superblock.
Ideally we just want to grab an active reference to superblock if we
can; that will make sure we won't go into inotify_umount_inodes() until
we are done. Cleanup is just deactivate_super().
However, that leaves a messy case - what if we *are* racing with
umount() and active references to superblock can't be acquired anymore?
We can bump ->s_count, grab ->s_umount, which will almost certainly wait
until the superblock is shut down and the watch in question is pining
for fjords. That's fine, but there is a problem - we might have hit the
window between ->s_active getting to 0 / ->s_count - below S_BIAS (i.e.
the moment when superblock is past the point of no return and is heading
for shutdown) and the moment when deactivate_super() acquires
->s_umount.
We could just do drop_super() yield() and retry, but that's rather
antisocial and this stuff is luser-triggerable. OTOH, having grabbed
->s_umount and having found that we'd got there first (i.e. that
->s_root is non-NULL) we know that we won't race with
inotify_umount_inodes().
So we could grab a reference to watch and do the rest as above, just
with drop_super() instead of deactivate_super(), right? Wrong. We had
to drop ih->mutex before we could grab ->s_umount. So the watch
could've been gone already.
That still can be dealt with - we need to save watch->wd, do idr_find()
and compare its result with our pointer. If they match, we either have
the damn thing still alive or we'd lost not one but two races at once,
the watch had been killed and a new one got created with the same ->wd
at the same address. That couldn't have happened in inotify_destroy(),
but inotify_rm_wd() could run into that. Still, "new one got created"
is not a problem - we have every right to kill it or leave it alone,
whatever's more convenient.
So we can use idr_find(...) == watch && watch->inode->i_sb == sb as
"grab it and kill it" check. If it's been our original watch, we are
fine, if it's a newcomer - nevermind, just pretend that we'd won the
race and kill the fscker anyway; we are safe since we know that its
superblock won't be going away.
And yes, this is far beyond mere "not very pretty"; so's the entire
concept of inotify to start with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-14 18:15:43 -07:00
|
|
|
call_rcu(&chunk->head, __put_chunk);
|
[PATCH] audit: watching subtrees
New kind of audit rule predicates: "object is visible in given subtree".
The part that can be sanely implemented, that is. Limitations:
* if you have hardlink from outside of tree, you'd better watch
it too (or just watch the object itself, obviously)
* if you mount something under a watched tree, tell audit
that new chunk should be added to watched subtrees
* if you umount something in a watched tree and it's still mounted
elsewhere, you will get matches on events happening there. New command
tells audit to recalculate the trees, trimming such sources of false
positives.
Note that it's _not_ about path - if something mounted in several places
(multiple mount, bindings, different namespaces, etc.), the match does
_not_ depend on which one we are using for access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2007-07-22 05:04:18 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
static const struct inotify_operations rtree_inotify_ops = {
|
|
|
|
.handle_event = handle_event,
|
|
|
|
.destroy_watch = destroy_watch,
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init audit_tree_init(void)
|
|
|
|
{
|
|
|
|
int i;
|
|
|
|
|
|
|
|
rtree_ih = inotify_init(&rtree_inotify_ops);
|
|
|
|
if (IS_ERR(rtree_ih))
|
|
|
|
audit_panic("cannot initialize inotify handle for rectree watches");
|
|
|
|
|
|
|
|
for (i = 0; i < HASH_SIZE; i++)
|
|
|
|
INIT_LIST_HEAD(&chunk_hash_heads[i]);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
__initcall(audit_tree_init);
|