userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr

 - Pass the user namespace the uid and gid values in the xattr are stored
   in into posix_acl_from_xattr.

 - Pass the user namespace kuid and kgid values should be converted into
   when storing uid and gid values in an xattr in posix_acl_to_xattr.

- Modify all callers of posix_acl_from_xattr and posix_acl_to_xattr to
  pass in &init_user_ns.

In the short term this change is not strictly needed but it makes the
code clearer.  In the longer term this change is necessary to be able to
mount filesystems outside of the initial user namespace that natively
store posix acls in the linux xattr format.

Cc: Theodore Tso <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
index 8bd5fcf06916..ad93ad0f1db0 100644
--- a/include/linux/posix_acl_xattr.h
+++ b/include/linux/posix_acl_xattr.h
@@ -64,7 +64,9 @@ static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
 }
 #endif
 
-struct posix_acl *posix_acl_from_xattr(const void *value, size_t size);
-int posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size);
+struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns, 
+				       const void *value, size_t size);
+int posix_acl_to_xattr(struct user_namespace *user_ns,
+		       const struct posix_acl *acl, void *buffer, size_t size);
 
 #endif	/* _POSIX_ACL_XATTR_H */