Quoting Kees Cook (keescook@xxxxxxxxxxxx):
> 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@xxxxxxxxxxxx>
> Cc: Serge E. Hallyn <serge@xxxxxxxxxx>
Makes sense, thanks.
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> fs/inode.c | 2 +-
> fs/namei.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index db5914783a71..7092debe90cc 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -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;
> }
> diff --git a/fs/namei.c b/fs/namei.c
> index 6571a5f5112e..efe53a5d0737 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -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);
> --
> 2.7.4
>
>
> --
> Kees Cook
> Pixel Security
