From 121d57af308d0cf943f08f4738d24d3966c38cd9 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Fri, 19 Jan 2018 09:29:18 -0500 Subject: [PATCH] gso: validate gso_type in GSO handlers Validate gso_type during segmentation as SKB_GSO_DODGY sources may pass packets where the gso_type does not match the contents. Syzkaller was able to enter the SCTP gso handler with a packet of gso_type SKB_GSO_TCPV4. On entry of transport layer gso handlers, verify that the gso_type matches the transport protocol. Fixes: 90017accff61 ("sctp: Add GSO support") Link: http://lkml.kernel.org/r/<001a1137452496ffc305617e5fe0@google.com> Reported-by: syzbot+fee64147a25aecd48055@syzkaller.appspotmail.com Signed-off-by: Willem de Bruijn Acked-by: Jason Wang Reviewed-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/ipv4/esp4_offload.c | 3 +++ net/ipv4/tcp_offload.c | 3 +++ net/ipv4/udp_offload.c | 3 +++ net/ipv6/esp6_offload.c | 3 +++ net/ipv6/tcpv6_offload.c | 3 +++ net/ipv6/udp_offload.c | 3 +++ net/sctp/offload.c | 3 +++ 7 files changed, 21 insertions(+) diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c index b1338e5..29b333a 100644 --- a/net/ipv4/esp4_offload.c +++ b/net/ipv4/esp4_offload.c @@ -122,6 +122,9 @@ static struct sk_buff *esp4_gso_segment(struct sk_buff *skb, if (!xo) goto out; + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP)) + goto out; + seq = xo->seq.low; x = skb->sp->xvec[skb->sp->len - 1]; diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index b6a2aa1..4d58e2c 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -32,6 +32,9 @@ static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq, static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, netdev_features_t features) { + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)) + return ERR_PTR(-EINVAL); + if (!pskb_may_pull(skb, sizeof(struct tcphdr))) return ERR_PTR(-EINVAL); diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 01801b7..ea6e6e7 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -203,6 +203,9 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, goto out; } + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP)) + goto out; + if (!pskb_may_pull(skb, sizeof(struct udphdr))) goto out; diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c index dd96274..f52c314 100644 --- a/net/ipv6/esp6_offload.c +++ b/net/ipv6/esp6_offload.c @@ -149,6 +149,9 @@ static struct sk_buff *esp6_gso_segment(struct sk_buff *skb, if (!xo) goto out; + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_ESP)) + goto out; + seq = xo->seq.low; x = skb->sp->xvec[skb->sp->len - 1]; diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c index d883c92..278e49c 100644 --- a/net/ipv6/tcpv6_offload.c +++ b/net/ipv6/tcpv6_offload.c @@ -46,6 +46,9 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb, { struct tcphdr *th; + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)) + return ERR_PTR(-EINVAL); + if (!pskb_may_pull(skb, sizeof(*th))) return ERR_PTR(-EINVAL); diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c index a0f89ad..2a04dc9 100644 --- a/net/ipv6/udp_offload.c +++ b/net/ipv6/udp_offload.c @@ -42,6 +42,9 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, const struct ipv6hdr *ipv6h; struct udphdr *uh; + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP)) + goto out; + if (!pskb_may_pull(skb, sizeof(struct udphdr))) goto out; diff --git a/net/sctp/offload.c b/net/sctp/offload.c index 275925b..35bc710 100644 --- a/net/sctp/offload.c +++ b/net/sctp/offload.c @@ -45,6 +45,9 @@ static struct sk_buff *sctp_gso_segment(struct sk_buff *skb, struct sk_buff *segs = ERR_PTR(-EINVAL); struct sctphdr *sh; + if (!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP)) + goto out; + sh = sctp_hdr(skb); if (!pskb_may_pull(skb, sizeof(*sh))) goto out; -- 2.7.4