[PATCH] fuse: Only allow read/writing user xattrs

[ebiederm@xmission.com (Eric W. Biederman)]

In the context of unprivileged mounts supporting anything except
xattrs with the "user." prefix seems foolish.  Return -EOPNOSUPP
for all other types of xattrs.

Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---

Do we really have a kernel bug as blantant as this appears?

 fs/fuse/dir.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 45a27c4..260de56 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/namei.h>
 #include <linux/slab.h>
+#include <linux/xattr.h>
 
 #if BITS_PER_LONG >= 64
 static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
@@ -1537,6 +1538,9 @@ static int fuse_setxattr(struct dentry *entry, const char *name,
 	if (fc->no_setxattr)
 		return -EOPNOTSUPP;
 
+	if (strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) != 0)
+		return -EOPNOTSUPP;
+
 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -1576,6 +1580,9 @@ static ssize_t fuse_getxattr(struct dentry *entry, const char *name,
 	if (fc->no_getxattr)
 		return -EOPNOTSUPP;
 
+	if (strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) != 0)
+		return -EOPNOTSUPP;
+
 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
-- 
1.7.5.4