fs: Reorder inode_owner_or_capable() to avoid needless

Checking for capabilities should be the last operation when performing
access control tests so that PF_SUPERPRIV is set only when it was required
for success (implying that the capability was needed for the operation).

Reported-by: Solar Designer <solar@openwall.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Kees Cook 2017-06-21 09:53:06 -07:00 committed by Al Viro
parent 41124db869
commit cc658db47d
2 changed files with 2 additions and 2 deletions

View File

@ -2023,7 +2023,7 @@ bool inode_owner_or_capable(const struct inode *inode)
return true;
ns = current_user_ns();
if (ns_capable(ns, CAP_FOWNER) && kuid_has_mapping(ns, inode->i_uid))
if (kuid_has_mapping(ns, inode->i_uid) && ns_capable(ns, CAP_FOWNER))
return true;
return false;
}

View File

@ -1008,7 +1008,7 @@ static int may_linkat(struct path *link)
/* Source inode owner (or CAP_FOWNER) can hardlink all they like,
* otherwise, it must be a safe source.
*/
if (inode_owner_or_capable(inode) || safe_hardlink_source(inode))
if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
return 0;
audit_log_link_denied("linkat", link);