Re: [PATCH v3] mm/memfd: add F_SEAL_EXEC
From: Kees Cook
Date: Fri Dec 02 2022 - 17:45:08 EST
On Fri, Dec 02, 2022 at 01:33:59AM +0000, jeffxu@xxxxxxxxxxxx wrote:
> From: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
>
> The new F_SEAL_EXEC flag will prevent modification of the exec bits:
> written as traditional octal mask, 0111, or as named flags, S_IXUSR |
> S_IXGRP | S_IXOTH. Any chmod(2) or similar call that attempts to modify
> any of these bits after the seal is applied will fail with errno EPERM.
>
> This will preserve the execute bits as they are at the time of sealing,
> so the memfd will become either permanently executable or permanently
> un-executable.
>
> Co-developed-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
> Signed-off-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
> Signed-off-by: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
Oh, one note on tag ordering here. Since you're sending it, I would
expect this to read as:
From: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
...
Signed-off-by: Daniel Verkamp <dverkamp@xxxxxxxxxxxx>
Co-developed-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
Signed-off-by: Jeff Xu <jeffxu@xxxxxxxxxxxx>
--
Kees Cook