On Thu, Apr 7, 2022 at 3:24 PM Xin Long <lucien.xin@xxxxxxxxx> wrote:
> Yi Chen reported an unexpected sctp connection abort, and it occurred when
> COOKIE_ECHO is bundled with DATA Fragment by SCTP HW GSO. As the IP header
> is included in chunk->head_skb instead of chunk->skb, it failed to check
> IP header version in security_sctp_assoc_request().
>
> According to Ondrej, SELinux only looks at IP header (address and IPsec
> options) and XFRM state data, and these are all included in head_skb for
> SCTP HW GSO packets. So fix it by using head_skb when calling
> security_sctp_assoc_request() in processing COOKIE_ECHO.
>
> v1->v2:
> - As Ondrej noticed, chunk->head_skb should also be used for
> security_sctp_assoc_established() in sctp_sf_do_5_1E_ca().
>
> Fixes: e215dab1c490 ("security: call security_sctp_assoc_request in sctp_sf_do_5_1D_ce")
> Reported-by: Yi Chen <yiche@xxxxxxxxxx>
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
> ---
> net/sctp/sm_statefuns.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 7f342bc12735..52edee1322fc 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -781,7 +781,7 @@ enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
> }
> }
>
> - if (security_sctp_assoc_request(new_asoc, chunk->skb)) {
> + if (security_sctp_assoc_request(new_asoc, chunk->head_skb ?: chunk->skb)) {
> sctp_association_free(new_asoc);
> return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
> }
> @@ -932,7 +932,7 @@ enum sctp_disposition sctp_sf_do_5_1E_ca(struct net *net,
>
> /* Set peer label for connection. */
> if (security_sctp_assoc_established((struct sctp_association *)asoc,
> - chunk->skb))
> + chunk->head_skb ?: chunk->skb))
> return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
>
> /* Verify that the chunk length for the COOKIE-ACK is OK.
> @@ -2262,7 +2262,7 @@ enum sctp_disposition sctp_sf_do_5_2_4_dupcook(
> }
>
> /* Update socket peer label if first association. */
> - if (security_sctp_assoc_request(new_asoc, chunk->skb)) {
> + if (security_sctp_assoc_request(new_asoc, chunk->head_skb ?: chunk->skb)) {
> sctp_association_free(new_asoc);
> return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
> }
> --
> 2.31.1
FWIW:
Reviewed-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
Thanks!
--
Ondrej Mosnacek
Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.
