[PATCH 4.9 52/59] sysfs: Do not return POSIX ACL xattrs via listxattr

Greg Kroah-Hartman
2018-10-08T18:40:21Z

From: Andreas Gruenbacher <agruenba@redhat.com>

commit ffc4c92227db5699493e43eb140b4cb5904c30ff upstream.

Commit 786534b92f3c introduced a regression that caused listxattr to
return the POSIX ACL attribute names even though sysfs doesn't support
POSIX ACLs. This happens because simple_xattr_list checks for NULL
i_acl / i_default_acl, but inode_init_always initializes those fields
to ACL_NOT_CACHED ((void *)-1). For example:
$ getfattr -m- -d /sys
/sys: system.posix_acl_access: Operation not supported
/sys: system.posix_acl_default: Operation not supported
Fix this in simple_xattr_list by checking if the filesystem supports POSIX ACLs.

Fixes: 786534b92f3c ("tmpfs: listxattr should include POSIX ACL xattrs")
Reported-by: Marc Aurèle La France <tsi@tuyoix.net>
Tested-by: Marc Aurèle La France <tsi@tuyoix.net>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xattr.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -953,17 +953,19 @@ ssize_t simple_xattr_list(struct inode *
int err = 0;

#ifdef CONFIG_FS_POSIX_ACL
- if (inode->i_acl) {
- err = xattr_list_one(&buffer, &remaining_size,
- XATTR_NAME_POSIX_ACL_ACCESS);
- if (err)
- return err;
- }
- if (inode->i_default_acl) {
- err = xattr_list_one(&buffer, &remaining_size,
- XATTR_NAME_POSIX_ACL_DEFAULT);
- if (err)
- return err;
+ if (IS_POSIXACL(inode)) {
+ if (inode->i_acl) {
+ err = xattr_list_one(&buffer, &remaining_size,
+ XATTR_NAME_POSIX_ACL_ACCESS);
+ if (err)
+ return err;
+ }
+ if (inode->i_default_acl) {
+ err = xattr_list_one(&buffer, &remaining_size,
+ XATTR_NAME_POSIX_ACL_DEFAULT);
+ if (err)
+ return err;
+ }
}
#endif