[ 052/133] ipv4: raw: fix icmp_filter()

Greg Kroah-Hartman
2012-10-10T22:55:21Z

From: Eric Dumazet <edumazet@google.com>

[ 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/raw.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- 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 */