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Message-Id: <1430991989-23170-84-git-send-email-luis.henriques@canonical.com>
Date: Thu, 7 May 2015 10:44:52 +0100
From: Luis Henriques <luis.henriques@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: David Sterba <dsterba@...e.cz>, Chris Mason <clm@...com>,
Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 083/180] btrfs: don't accept bare namespace as a valid xattr
3.16.7-ckt11 -stable review patch. If anyone has any objections, please let me know.
------------------
From: David Sterba <dsterba@...e.cz>
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@...el.com>
Signed-off-by: David Sterba <dsterba@...e.cz>
Signed-off-by: Chris Mason <clm@...com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
fs/btrfs/xattr.c | 53 +++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 39 insertions(+), 14 deletions(-)
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 7b29ee23b4ad..618e86ceede7 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -360,22 +360,42 @@ 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) ||
- !strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_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 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
+ prefixlen = XATTR_BTRFS_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
@@ -384,8 +404,9 @@ 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);
}
@@ -393,6 +414,7 @@ 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
@@ -409,8 +431,9 @@ 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 (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
return btrfs_set_prop(dentry->d_inode, name,
@@ -426,6 +449,7 @@ 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
@@ -442,8 +466,9 @@ 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;
if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
return btrfs_set_prop(dentry->d_inode, name,
--
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