ipv4: raw: fix icmp_filter()

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>

1 files changed, 8 insertions, 6 deletions

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index ff0f071969ea..d23c6571ba1c 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -131,18 +131,20 @@ found:
  *      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;
 
-        type = icmp_hdr(skb)->type;
-        if (type < 32) {
+        if (hdr->type < 32) {
                 __u32 data = raw_sk(sk)->filter.data;
 
-                return ((1 << type) & data) != 0;
+                return ((1U << hdr->type) & data) != 0;
         }
 
         /* Do not block unknown ICMP types */