FROMLIST: Add flags option to get xattr method paired to __vfs_getxattrwip/beryllium-mainline-v5.11-rc2

Add a flag option to get xattr method that could have a bit flag of
XATTR_NOSECURITY passed to it.  XATTR_NOSECURITY is generally then
set in the __vfs_getxattr path when called by security
infrastructure.

This handles the case of a union filesystem driver that is being
requested by the security layer to report back the xattr data.

For the use case where access is to be blocked by the security layer.

The path then could be security(dentry) ->
__vfs_getxattr(dentry...XATTR_NOSECURITY) ->
handler->get(dentry...XATTR_NOSECURITY) ->
__vfs_getxattr(lower_dentry...XATTR_NOSECURITY) ->
lower_handler->get(lower_dentry...XATTR_NOSECURITY)
which would report back through the chain data and success as
expected, the logging security layer at the top would have the
data to determine the access permissions and report back the target
context that was blocked.

Without the get handler flag, the path on a union filesystem would be
the errant security(dentry) -> __vfs_getxattr(dentry) ->
handler->get(dentry) -> vfs_getxattr(lower_dentry) -> nested ->
security(lower_dentry, log off) -> lower_handler->get(lower_dentry)
which would report back through the chain no data, and -EACCES.

For selinux for both cases, this would translate to a correctly
determined blocked access. In the first case with this change a correct avc
log would be reported, in the second legacy case an incorrect avc log
would be reported against an uninitialized u:object_r:unlabeled:s0
context making the logs cosmetically useless for audit2allow.

This patch series is inert and is the wide-spread addition of the
flags option for xattr functions, and a replacement of __vfs_getxattr
with __vfs_getxattr(...XATTR_NOSECURITY).

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Jeff Layton <jlayton@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Mike Marshall <hubcap@omnibond.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com
Cc: linux-security-module@vger.kernel.org

(cherry picked from (rejected from archive because of too many recipients))
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 133515582
Bug: 136124883
Bug: 129319403
Change-Id: Iabbb8771939d5f66667a26bb23ddf4c562c349a1
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 9ccd19d8f7b1..0ed0a61d4c5f 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -7242,7 +7242,8 @@ leave:
  */
 static int ocfs2_xattr_security_get(const struct xattr_handler *handler,
 				    struct dentry *unused, struct inode *inode,
-				    const char *name, void *buffer, size_t size)
+				    const char *name, void *buffer, size_t size,
+				    int flags)
 {
 	return ocfs2_xattr_get(inode, OCFS2_XATTR_INDEX_SECURITY,
 			       name, buffer, size);
@@ -7314,7 +7315,8 @@ const struct xattr_handler ocfs2_xattr_security_handler = {
  */
 static int ocfs2_xattr_trusted_get(const struct xattr_handler *handler,
 				   struct dentry *unused, struct inode *inode,
-				   const char *name, void *buffer, size_t size)
+				   const char *name, void *buffer, size_t size,
+				   int flags)
 {
 	return ocfs2_xattr_get(inode, OCFS2_XATTR_INDEX_TRUSTED,
 			       name, buffer, size);
@@ -7340,7 +7342,8 @@ const struct xattr_handler ocfs2_xattr_trusted_handler = {
  */
 static int ocfs2_xattr_user_get(const struct xattr_handler *handler,
 				struct dentry *unused, struct inode *inode,
-				const char *name, void *buffer, size_t size)
+				const char *name, void *buffer, size_t size,
+				int flags)
 {
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);