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 <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 21 insertions, 0 deletions

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index b1338e576d00..29b333a62ab0 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 b6a2aa1dcf56..4d58e2ce0b5b 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 01801b77bd0d..ea6e6e7df0ee 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 dd9627490c7c..f52c314d4c97 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 d883c9204c01..278e49cd67d4 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 a0f89ad76f9d..2a04dc9c781b 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 275925b93b29..35bc7106d182 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;