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eventfs: Cleanup permissions in creation of inodes

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The permissions being set during the creation of the inodes was updating
eventfs_inode attributes as well. Those attributes should only be touched
by the setattr or remount operations, not during the creation of inodes.
The eventfs_inode attributes should only be used to set the inodes and
should not be modified during the inode creation.

Simplify the code and fix the situation by:

 1) Removing the eventfs_find_events() and doing a simple lookup for
    the events descriptor in eventfs_get_inode()

 2) Remove update_events_attr() as the attributes should only be used
    to update the inode and should not be modified here.

 3) Add update_inode_attr() that uses the attributes to determine what
    the inode permissions should be.

 4) As the parent_inode of the eventfs_root_inode structure is no longer
    needed, remove it.

Now on creation, the inode gets the proper permissions without causing
side effects to the ei->attr field.

Link: https://lore.kernel.org/lkml/20240522165031.944088388@goodmis.org

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-05-22 12:49:45 -04:00
parent 37cd0d1266
commit 6e3d7c903c
1 changed files with 23 additions and 67 deletions
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90
fs/tracefs/event_inode.c
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@ -37,7 +37,6 @@ static DEFINE_MUTEX(eventfs_mutex);
struct eventfs_root_inode {
struct eventfs_inode ei;
struct inode *parent_inode;
struct dentry *events_dir;
};
@ -229,27 +228,6 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
return ret;
}
static void update_events_attr(struct eventfs_inode *ei, struct super_block *sb)
{
struct eventfs_root_inode *rei;
struct inode *parent;
rei = get_root_inode(ei);
/* Use the parent inode permissions unless root set its permissions */
parent = rei->parent_inode;
if (rei->ei.attr.mode & EVENTFS_SAVE_UID)
ei->attr.uid = rei->ei.attr.uid;
else
ei->attr.uid = parent->i_uid;
if (rei->ei.attr.mode & EVENTFS_SAVE_GID)
ei->attr.gid = rei->ei.attr.gid;
else
ei->attr.gid = parent->i_gid;
}
static const struct inode_operations eventfs_dir_inode_operations = {
.lookup = eventfs_root_lookup,
.setattr = eventfs_set_attr,
@ -321,60 +299,30 @@ void eventfs_remount(struct tracefs_inode *ti, bool update_uid, bool update_gid)
update_gid, ti->vfs_inode.i_gid, 0);
}
/* Return the evenfs_inode of the "events" directory */
static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
static void update_inode_attr(struct inode *inode, umode_t mode,
struct eventfs_attr *attr, struct eventfs_root_inode *rei)
{
struct eventfs_inode *ei;
do {
// The parent is stable because we do not do renames
dentry = dentry->d_parent;
// ... and directories always have d_fsdata
ei = dentry->d_fsdata;
/*
* If the ei is being freed, the ownership of the children
* doesn't matter.
*/
if (ei->is_freed)
return NULL;
// Walk upwards until you find the events inode
} while (!ei->is_events);
update_events_attr(ei, dentry->d_sb);
return ei;
}
static void update_inode_attr(struct dentry *dentry, struct inode *inode,
struct eventfs_attr *attr, umode_t mode)
{
struct eventfs_inode *events_ei = eventfs_find_events(dentry);
if (!events_ei)
return;
inode->i_mode = mode;
inode->i_uid = events_ei->attr.uid;
inode->i_gid = events_ei->attr.gid;
if (!attr)
return;
if (attr->mode & EVENTFS_SAVE_MODE)
if (attr && attr->mode & EVENTFS_SAVE_MODE)
inode->i_mode = attr->mode & EVENTFS_MODE_MASK;
else
inode->i_mode = mode;
if (attr->mode & EVENTFS_SAVE_UID)
if (attr && attr->mode & EVENTFS_SAVE_UID)
inode->i_uid = attr->uid;
else
inode->i_uid = rei->ei.attr.uid;
if (attr->mode & EVENTFS_SAVE_GID)
if (attr && attr->mode & EVENTFS_SAVE_GID)
inode->i_gid = attr->gid;
else
inode->i_gid = rei->ei.attr.gid;
}
static struct inode *eventfs_get_inode(struct dentry *dentry, struct eventfs_attr *attr,
umode_t mode, struct eventfs_inode *ei)
{
struct eventfs_root_inode *rei;
struct eventfs_inode *pei;
struct tracefs_inode *ti;
struct inode *inode;
@ -386,7 +334,16 @@ static struct inode *eventfs_get_inode(struct dentry *dentry, struct eventfs_att
ti->private = ei;
ti->flags |= TRACEFS_EVENT_INODE;
update_inode_attr(dentry, inode, attr, mode);
/* Find the top dentry that holds the "events" directory */
do {
dentry = dentry->d_parent;
/* Directories always have d_fsdata */
pei = dentry->d_fsdata;
} while (!pei->is_events);
rei = get_root_inode(pei);
update_inode_attr(inode, mode, attr, rei);
return inode;
}
@ -823,7 +780,6 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
// Note: we have a ref to the dentry from tracefs_start_creating()
rei = get_root_inode(ei);
rei->events_dir = dentry;
rei->parent_inode = d_inode(dentry->d_sb->s_root);
ei->entries = entries;
ei->nr_entries = size;