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>

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index b1338e5..29b333a 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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 (file)
--- 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;