ipv4: raw: fix icmp_filter()

[ Upstream commit ab43ed8b7490cb387782423ecf74aeee7237e591 ]

icmp_filter() should not modify its input, or else its caller
would need to recompute ip_hdr() if skb->head is reallocated.

Use skb_header_pointer() instead of pskb_may_pull() and
change the prototype to make clear both sk and skb are const.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 007e2eb..e1d4f30 100644 (file)
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -131,18 +131,20 @@ found:
  *     0 - deliver
  *     1 - block
  */
  *     0 - deliver
  *     1 - block
  */

-static __inline__ int icmp_filter(struct sock *sk, struct sk_buff *skb)
+static int icmp_filter(const struct sock *sk, const struct sk_buff *skb)

 {
 {

-       int type;
+       struct icmphdr _hdr;
+       const struct icmphdr *hdr;

 
 

-       if (!pskb_may_pull(skb, sizeof(struct icmphdr)))
+       hdr = skb_header_pointer(skb, skb_transport_offset(skb),
+                                sizeof(_hdr), &_hdr);
+       if (!hdr)

                return 1;
 
                return 1;
 

-       type = icmp_hdr(skb)->type;
-       if (type < 32) {
+       if (hdr->type < 32) {

                __u32 data = raw_sk(sk)->filter.data;
 
                __u32 data = raw_sk(sk)->filter.data;
 

-               return ((1 << type) & data) != 0;
+               return ((1U << hdr->type) & data) != 0;

        }
 
        /* Do not block unknown ICMP types */
        }
 
        /* Do not block unknown ICMP types */