From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f194.google.com ([209.85.192.194]:45188 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753154AbeB0NIk (ORCPT ); Tue, 27 Feb 2018 08:08:40 -0500 Received: by mail-pf0-f194.google.com with SMTP id j24so7906643pff.12 for ; Tue, 27 Feb 2018 05:08:40 -0800 (PST) From: Daniel Axtens To: netdev@vger.kernel.org Cc: Daniel Axtens , Marcelo Ricardo Leitner Subject: [PATCH 6/6] net: filter: refuse to change gso_size of SCTP packets Date: Wed, 28 Feb 2018 00:04:07 +1100 Message-Id: <20180227130407.22498-7-dja@axtens.net> In-Reply-To: <20180227130407.22498-1-dja@axtens.net> References: <20180227130407.22498-1-dja@axtens.net> Sender: netdev-owner@vger.kernel.org List-ID: An eBPF tc action on a veth pair can be passed an SCTP GSO skb, which has gso_size of GSO_BY_FRAGS. If that action calls bpf_skb_change_proto(), bpf_skb_net_grow() or bpf_skb_net_shrink(), the code will unconditionally attempt to increment or decrement the gso_size to some nonsense value. It's not clear how this could be done correctly, so simply refuse to operate on SCTP GSO skbs. Cc: Marcelo Ricardo Leitner Signed-off-by: Daniel Axtens --- Marcelo - I am not an SCTP expert by any means, so if this code should be doing something else, please let me know. --- net/core/filter.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index d9684d8a3ac7..f189c988962e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2096,6 +2096,10 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb) return ret; if (skb_is_gso(skb)) { + /* SCTP uses GSO_BY_FRAGS, cannot adjust */ + if (unlikely(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)) + return -ENOTSUPP; + /* SKB_GSO_TCPV4 needs to be changed into * SKB_GSO_TCPV6. */ @@ -2132,6 +2136,10 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb) return ret; if (skb_is_gso(skb)) { + /* SCTP uses GSO_BY_FRAGS, cannot adjust */ + if (unlikely(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)) + return -ENOTSUPP; + /* SKB_GSO_TCPV6 needs to be changed into * SKB_GSO_TCPV4. */ @@ -2252,6 +2260,10 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff) return ret; if (skb_is_gso(skb)) { + /* SCTP uses GSO_BY_FRAGS, cannot adjust */ + if (unlikely(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)) + return -ENOTSUPP; + /* Due to header grow, MSS needs to be downgraded. */ skb_decrease_gso_size(skb, len_diff); /* Header must be checked, and gso_segs recomputed. */ @@ -2276,6 +2288,10 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 len_diff) return ret; if (skb_is_gso(skb)) { + /* SCTP uses GSO_BY_FRAGS, cannot adjust */ + if (unlikely(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)) + return -ENOTSUPP; + /* Due to header shrink, MSS can be upgraded. */ skb_increase_gso_size(skb, len_diff); /* Header must be checked, and gso_segs recomputed. */ -- 2.14.1