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linux/fs/reiserfs/xattr_acl.c
Satyam Sharma 3bd858ab1c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 
Introduce is_owner_or_cap() macro in fs.h, and convert over relevant
users to it. This is done because we want to avoid bugs in the future
where we check for only effective fsuid of the current task against a
file's owning uid, without simultaneously checking for CAP_FOWNER as
well, thus violating its semantics.
[ XFS uses special macros and structures, and in general looked ...
untouchable, so we leave it alone -- but it has been looked over. ]

The (current->fsuid != inode->i_uid) check in generic_permission() and
exec_permission_lite() is left alone, because those operations are
covered by CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH. Similarly operations
falling under the purview of CAP_CHOWN and CAP_LEASE are also left alone.

Signed-off-by: Satyam Sharma <ssatyam@cse.iitk.ac.in>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 12:00:03 -07:00

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#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/posix_acl.h>
#include <linux/reiserfs_fs.h>
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/reiserfs_xattr.h>
#include <linux/reiserfs_acl.h>
#include <asm/uaccess.h>
static int reiserfs_set_acl(struct inode *inode, int type,
struct posix_acl *acl);
static int
xattr_set_acl(struct inode *inode, int type, const void *value, size_t size)
{
struct posix_acl *acl;
int error;
if (!reiserfs_posixacl(inode->i_sb))
return -EOPNOTSUPP;
if (!is_owner_or_cap(inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(value, size);
if (IS_ERR(acl)) {
return PTR_ERR(acl);
} else if (acl) {
error = posix_acl_valid(acl);
if (error)
goto release_and_out;
}
} else
acl = NULL;
error = reiserfs_set_acl(inode, type, acl);
release_and_out:
posix_acl_release(acl);
return error;
}
static int
xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
{
struct posix_acl *acl;
int error;
if (!reiserfs_posixacl(inode->i_sb))
return -EOPNOTSUPP;
acl = reiserfs_get_acl(inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl == NULL)
return -ENODATA;
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
return error;
}
/*
* Convert from filesystem to in-memory representation.
*/
static struct posix_acl *posix_acl_from_disk(const void *value, size_t size)
{
const char *end = (char *)value + size;
int n, count;
struct posix_acl *acl;
if (!value)
return NULL;
if (size < sizeof(reiserfs_acl_header))
return ERR_PTR(-EINVAL);
if (((reiserfs_acl_header *) value)->a_version !=
cpu_to_le32(REISERFS_ACL_VERSION))
return ERR_PTR(-EINVAL);
value = (char *)value + sizeof(reiserfs_acl_header);
count = reiserfs_acl_count(size);
if (count < 0)
return ERR_PTR(-EINVAL);
if (count == 0)
return NULL;
acl = posix_acl_alloc(count, GFP_NOFS);
if (!acl)
return ERR_PTR(-ENOMEM);
for (n = 0; n < count; n++) {
reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
goto fail;
acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
value = (char *)value +
sizeof(reiserfs_acl_entry_short);
acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
case ACL_GROUP:
value = (char *)value + sizeof(reiserfs_acl_entry);
if ((char *)value > end)
goto fail;
acl->a_entries[n].e_id = le32_to_cpu(entry->e_id);
break;
default:
goto fail;
}
}
if (value != end)
goto fail;
return acl;
fail:
posix_acl_release(acl);
return ERR_PTR(-EINVAL);
}
/*
* Convert from in-memory to filesystem representation.
*/
static void *posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
{
reiserfs_acl_header *ext_acl;
char *e;
int n;
*size = reiserfs_acl_size(acl->a_count);
ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
acl->a_count *
sizeof(reiserfs_acl_entry),
GFP_NOFS);
if (!ext_acl)
return ERR_PTR(-ENOMEM);
ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
e = (char *)ext_acl + sizeof(reiserfs_acl_header);
for (n = 0; n < acl->a_count; n++) {
reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER:
case ACL_GROUP:
entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
e += sizeof(reiserfs_acl_entry);
break;
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
e += sizeof(reiserfs_acl_entry_short);
break;
default:
goto fail;
}
}
return (char *)ext_acl;
fail:
kfree(ext_acl);
return ERR_PTR(-EINVAL);
}
/*
* Inode operation get_posix_acl().
*
* inode->i_mutex: down
* BKL held [before 2.5.x]
*/
struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
{
char *name, *value;
struct posix_acl *acl, **p_acl;
int size;
int retval;
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
p_acl = &reiserfs_i->i_acl_access;
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
p_acl = &reiserfs_i->i_acl_default;
break;
default:
return ERR_PTR(-EINVAL);
}
if (IS_ERR(*p_acl)) {
if (PTR_ERR(*p_acl) == -ENODATA)
return NULL;
} else if (*p_acl != NULL)
return posix_acl_dup(*p_acl);
size = reiserfs_xattr_get(inode, name, NULL, 0);
if (size < 0) {
if (size == -ENODATA || size == -ENOSYS) {
*p_acl = ERR_PTR(-ENODATA);
return NULL;
}
return ERR_PTR(size);
}
value = kmalloc(size, GFP_NOFS);
if (!value)
return ERR_PTR(-ENOMEM);
retval = reiserfs_xattr_get(inode, name, value, size);
if (retval == -ENODATA || retval == -ENOSYS) {
/* This shouldn't actually happen as it should have
been caught above.. but just in case */
acl = NULL;
*p_acl = ERR_PTR(-ENODATA);
} else if (retval < 0) {
acl = ERR_PTR(retval);
} else {
acl = posix_acl_from_disk(value, retval);
if (!IS_ERR(acl))
*p_acl = posix_acl_dup(acl);
}
kfree(value);
return acl;
}
/*
* Inode operation set_posix_acl().
*
* inode->i_mutex: down
* BKL held [before 2.5.x]
*/
static int
reiserfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
{
char *name;
void *value = NULL;
struct posix_acl **p_acl;
size_t size;
int error;
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
p_acl = &reiserfs_i->i_acl_access;
if (acl) {
mode_t mode = inode->i_mode;
error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
return error;
else {
inode->i_mode = mode;
if (error == 0)
acl = NULL;
}
}
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
p_acl = &reiserfs_i->i_acl_default;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
value = posix_acl_to_disk(acl, &size);
if (IS_ERR(value))
return (int)PTR_ERR(value);
error = reiserfs_xattr_set(inode, name, value, size, 0);
} else {
error = reiserfs_xattr_del(inode, name);
if (error == -ENODATA) {
/* This may seem odd here, but it means that the ACL was set
* with a value representable with mode bits. If there was
* an ACL before, reiserfs_xattr_del already dirtied the inode.
*/
mark_inode_dirty(inode);
error = 0;
}
}
kfree(value);
if (!error) {
/* Release the old one */
if (!IS_ERR(*p_acl) && *p_acl)
posix_acl_release(*p_acl);
if (acl == NULL)
*p_acl = ERR_PTR(-ENODATA);
else
*p_acl = posix_acl_dup(acl);
}
return error;
}
/* dir->i_mutex: locked,
* inode is new and not released into the wild yet */
int
reiserfs_inherit_default_acl(struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
struct posix_acl *acl;
int err = 0;
/* ACLs only get applied to files and directories */
if (S_ISLNK(inode->i_mode))
return 0;
/* ACLs can only be used on "new" objects, so if it's an old object
* there is nothing to inherit from */
if (get_inode_sd_version(dir) == STAT_DATA_V1)
goto apply_umask;
/* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
* would be useless since permissions are ignored, and a pain because
* it introduces locking cycles */
if (is_reiserfs_priv_object(dir)) {
reiserfs_mark_inode_private(inode);
goto apply_umask;
}
acl = reiserfs_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl)) {
if (PTR_ERR(acl) == -ENODATA)
goto apply_umask;
return PTR_ERR(acl);
}
if (acl) {
struct posix_acl *acl_copy;
mode_t mode = inode->i_mode;
int need_acl;
/* Copy the default ACL to the default ACL of a new directory */
if (S_ISDIR(inode->i_mode)) {
err = reiserfs_set_acl(inode, ACL_TYPE_DEFAULT, acl);
if (err)
goto cleanup;
}
/* Now we reconcile the new ACL and the mode,
potentially modifying both */
acl_copy = posix_acl_clone(acl, GFP_NOFS);
if (!acl_copy) {
err = -ENOMEM;
goto cleanup;
}
need_acl = posix_acl_create_masq(acl_copy, &mode);
if (need_acl >= 0) {
if (mode != inode->i_mode) {
inode->i_mode = mode;
}
/* If we need an ACL.. */
if (need_acl > 0) {
err =
reiserfs_set_acl(inode, ACL_TYPE_ACCESS,
acl_copy);
if (err)
goto cleanup_copy;
}
}
cleanup_copy:
posix_acl_release(acl_copy);
cleanup:
posix_acl_release(acl);
} else {
apply_umask:
/* no ACL, apply umask */
inode->i_mode &= ~current->fs->umask;
}
return err;
}
/* Looks up and caches the result of the default ACL.
* We do this so that we don't need to carry the xattr_sem into
* reiserfs_new_inode if we don't need to */
int reiserfs_cache_default_acl(struct inode *inode)
{
int ret = 0;
if (reiserfs_posixacl(inode->i_sb) && !is_reiserfs_priv_object(inode)) {
struct posix_acl *acl;
reiserfs_read_lock_xattr_i(inode);
reiserfs_read_lock_xattrs(inode->i_sb);
acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
reiserfs_read_unlock_xattrs(inode->i_sb);
reiserfs_read_unlock_xattr_i(inode);
ret = (acl && !IS_ERR(acl));
if (ret)
posix_acl_release(acl);
}
return ret;
}
int reiserfs_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int error;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
!reiserfs_posixacl(inode->i_sb)) {
return 0;
}
reiserfs_read_lock_xattrs(inode->i_sb);
acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
reiserfs_read_unlock_xattrs(inode->i_sb);
if (!acl)
return 0;
if (IS_ERR(acl))
return PTR_ERR(acl);
clone = posix_acl_clone(acl, GFP_NOFS);
posix_acl_release(acl);
if (!clone)
return -ENOMEM;
error = posix_acl_chmod_masq(clone, inode->i_mode);
if (!error) {
int lock = !has_xattr_dir(inode);
reiserfs_write_lock_xattr_i(inode);
if (lock)
reiserfs_write_lock_xattrs(inode->i_sb);
else
reiserfs_read_lock_xattrs(inode->i_sb);
error = reiserfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
if (lock)
reiserfs_write_unlock_xattrs(inode->i_sb);
else
reiserfs_read_unlock_xattrs(inode->i_sb);
reiserfs_write_unlock_xattr_i(inode);
}
posix_acl_release(clone);
return error;
}
static int
posix_acl_access_get(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_ACCESS) - 1)
return -EINVAL;
return xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int
posix_acl_access_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_ACCESS) - 1)
return -EINVAL;
return xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}
static int posix_acl_access_del(struct inode *inode, const char *name)
{
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
struct posix_acl **acl = &reiserfs_i->i_acl_access;
if (strlen(name) != sizeof(POSIX_ACL_XATTR_ACCESS) - 1)
return -EINVAL;
if (!IS_ERR(*acl) && *acl) {
posix_acl_release(*acl);
*acl = ERR_PTR(-ENODATA);
}
return 0;
}
static int
posix_acl_access_list(struct inode *inode, const char *name, int namelen,
char *out)
{
int len = namelen;
if (!reiserfs_posixacl(inode->i_sb))
return 0;
if (out)
memcpy(out, name, len);
return len;
}
struct reiserfs_xattr_handler posix_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.get = posix_acl_access_get,
.set = posix_acl_access_set,
.del = posix_acl_access_del,
.list = posix_acl_access_list,
};
static int
posix_acl_default_get(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_DEFAULT) - 1)
return -EINVAL;
return xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}
static int
posix_acl_default_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_DEFAULT) - 1)
return -EINVAL;
return xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}
static int posix_acl_default_del(struct inode *inode, const char *name)
{
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
struct posix_acl **acl = &reiserfs_i->i_acl_default;
if (strlen(name) != sizeof(POSIX_ACL_XATTR_DEFAULT) - 1)
return -EINVAL;
if (!IS_ERR(*acl) && *acl) {
posix_acl_release(*acl);
*acl = ERR_PTR(-ENODATA);
}
return 0;
}
static int
posix_acl_default_list(struct inode *inode, const char *name, int namelen,
char *out)
{
int len = namelen;
if (!reiserfs_posixacl(inode->i_sb))
return 0;
if (out)
memcpy(out, name, len);
return len;
}
struct reiserfs_xattr_handler posix_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.get = posix_acl_default_get,
.set = posix_acl_default_set,
.del = posix_acl_default_del,
.list = posix_acl_default_list,
};
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