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btrfs: don't accept bare namespace as a valid xattr

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commit 3c3b04d10ff1811a27f86684ccd2f5ba6983211d upstream.

Due to insufficient check in btrfs_is_valid_xattr, this unexpectedly
works:

 $ touch file
 $ setfattr -n user. -v 1 file
 $ getfattr -d file
user.="1"

ie. the missing attribute name after the namespace.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94291
Reported-by: William Douglas <william.douglas@intel.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
[lizf: Backported to 3.4:
 - 3.4 doesn't support XATTR_BTRFS_PREFIX]
Signed-off-by: Zefan Li <lizefan@huawei.com>
This commit is contained in:
David Sterba 2015-03-25 19:26:41 +01:00 committed by Zefan Li
parent abe62247e0
commit 60ba3db7e7
1 changed files with 37 additions and 13 deletions
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50
fs/btrfs/xattr.c
View file

@ -310,21 +310,40 @@ const struct xattr_handler *btrfs_xattr_handlers[] = {
/*
* Check if the attribute is in a supported namespace.
*
* This applied after the check for the synthetic attributes in the system
* This is applied after the check for the synthetic attributes in the system
* namespace.
*/
static bool btrfs_is_valid_xattr(const char *name)
static int btrfs_is_valid_xattr(const char *name)
{
return !strncmp(name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN) ||
!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
int len = strlen(name);
int prefixlen = 0;
if (!strncmp(name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN))
prefixlen = XATTR_SECURITY_PREFIX_LEN;
else if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
prefixlen = XATTR_SYSTEM_PREFIX_LEN;
else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
prefixlen = XATTR_TRUSTED_PREFIX_LEN;
else if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
prefixlen = XATTR_USER_PREFIX_LEN;
else
return -EOPNOTSUPP;
/*
* The name cannot consist of just prefix
*/
if (len <= prefixlen)
return -EINVAL;
return 0;
}
ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
int ret;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
@ -333,8 +352,9 @@ ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_getxattr(dentry, name, buffer, size);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
}
@ -342,6 +362,7 @@ int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags)
{
struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
int ret;
/*
* The permission on security.* and system.* is not checked
@ -358,8 +379,9 @@ int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_setxattr(dentry, name, value, size, flags);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
if (size == 0)
value = ""; /* empty EA, do not remove */
@ -371,6 +393,7 @@ int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
int btrfs_removexattr(struct dentry *dentry, const char *name)
{
struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
int ret;
/*
* The permission on security.* and system.* is not checked
@ -387,8 +410,9 @@ int btrfs_removexattr(struct dentry *dentry, const char *name)
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_removexattr(dentry, name);
if (!btrfs_is_valid_xattr(name))
return -EOPNOTSUPP;
ret = btrfs_is_valid_xattr(name);
if (ret)
return ret;
return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
XATTR_REPLACE);