act_nat: fix on the TX path

On the TX path, skb->data points to the ethernet header, not the network
header. So when validating the packet length for accessing we should
take the ethernet header into account.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 10 deletions

diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index d0386a413e8d..509a2d53a99d 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -114,6 +114,7 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
         int egress;
         int action;
         int ihl;
+        int noff;
 
         spin_lock(&p->tcf_lock);
 
@@ -132,7 +133,8 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
         if (unlikely(action == TC_ACT_SHOT))
                 goto drop;
 
-        if (!pskb_may_pull(skb, sizeof(*iph)))
+        noff = skb_network_offset(skb);
+        if (!pskb_may_pull(skb, sizeof(*iph) + noff))
                 goto drop;
 
         iph = ip_hdr(skb);
@@ -144,7 +146,7 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
 
         if (!((old_addr ^ addr) & mask)) {
                 if (skb_cloned(skb) &&
-                    !skb_clone_writable(skb, sizeof(*iph)) &&
+                    !skb_clone_writable(skb, sizeof(*iph) + noff) &&
                     pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
                         goto drop;
 
@@ -172,9 +174,9 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
         {
                 struct tcphdr *tcph;
 
-                if (!pskb_may_pull(skb, ihl + sizeof(*tcph)) ||
+                if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
                     (skb_cloned(skb) &&
-                     !skb_clone_writable(skb, ihl + sizeof(*tcph)) &&
+                     !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
                      pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
                         goto drop;
 
@@ -186,9 +188,9 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
         {
                 struct udphdr *udph;
 
-                if (!pskb_may_pull(skb, ihl + sizeof(*udph)) ||
+                if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
                     (skb_cloned(skb) &&
-                     !skb_clone_writable(skb, ihl + sizeof(*udph)) &&
+                     !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
                      pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
                         goto drop;
 
@@ -205,7 +207,7 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
         {
                 struct icmphdr *icmph;
 
-                if (!pskb_may_pull(skb, ihl + sizeof(*icmph)))
+                if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
                         goto drop;
 
                 icmph = (void *)(skb_network_header(skb) + ihl);
@@ -215,7 +217,8 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
                     (icmph->type != ICMP_PARAMETERPROB))
                         break;
 
-                if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
+                if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
+                                        noff))
                         goto drop;
 
                 icmph = (void *)(skb_network_header(skb) + ihl);
@@ -229,8 +232,8 @@ static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
                         break;
 
                 if (skb_cloned(skb) &&
-                    !skb_clone_writable(skb,
-                                        ihl + sizeof(*icmph) + sizeof(*iph)) &&
+                    !skb_clone_writable(skb, ihl + sizeof(*icmph) +
+                                             sizeof(*iph) + noff) &&
                     pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
                         goto drop;