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SubjectRe: Kernel 2.6.13 breaks libpcap (and tcpdump).
Date
Andrew Morton <akpm@osdl.org> wrote:
>
>> Filter incoming data, looking for ICMP messages:
>>
>> tcpdump -f "ip proto \icmp"
>>
>> Well, that catches nothing.

We aren't handling the reading of specific fields like the IP protocol
field correctly. This patch should make it work again.

I tried to move this logic into the new load_pointer function but it
all came out messy so I simply rolled it back.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Cheers,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff --git a/net/core/filter.c b/net/core/filter.c
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -36,7 +36,7 @@
#include <linux/filter.h>

/* No hurry in this branch */
-static void *__load_pointer(struct sk_buff *skb, int k)
+static void *load_pointer(struct sk_buff *skb, int k)
{
u8 *ptr = NULL;

@@ -50,18 +50,6 @@ static void *__load_pointer(struct sk_bu
return NULL;
}

-static inline void *load_pointer(struct sk_buff *skb, int k,
- unsigned int size, void *buffer)
-{
- if (k >= 0)
- return skb_header_pointer(skb, k, size, buffer);
- else {
- if (k >= SKF_AD_OFF)
- return NULL;
- return __load_pointer(skb, k);
- }
-}
-
/**
* sk_run_filter - run a filter on a socket
* @skb: buffer to run the filter on
@@ -177,7 +165,13 @@ int sk_run_filter(struct sk_buff *skb, s
case BPF_LD|BPF_W|BPF_ABS:
k = fentry->k;
load_w:
- ptr = load_pointer(skb, k, 4, &tmp);
+ if (k >= 0)
+ ptr = skb_header_pointer(skb, k, 4, &tmp);
+ else if (k < SKF_AD_OFF)
+ ptr = load_pointer(skb, k);
+ else
+ break;
+
if (ptr != NULL) {
A = ntohl(*(u32 *)ptr);
continue;
@@ -186,7 +180,13 @@ int sk_run_filter(struct sk_buff *skb, s
case BPF_LD|BPF_H|BPF_ABS:
k = fentry->k;
load_h:
- ptr = load_pointer(skb, k, 2, &tmp);
+ if (k >= 0)
+ ptr = skb_header_pointer(skb, k, 2, &tmp);
+ else if (k < SKF_AD_OFF)
+ ptr = load_pointer(skb, k);
+ else
+ break;
+
if (ptr != NULL) {
A = ntohs(*(u16 *)ptr);
continue;
@@ -195,7 +195,13 @@ int sk_run_filter(struct sk_buff *skb, s
case BPF_LD|BPF_B|BPF_ABS:
k = fentry->k;
load_b:
- ptr = load_pointer(skb, k, 1, &tmp);
+ if (k >= 0)
+ ptr = skb_header_pointer(skb, k, 1, &tmp);
+ else if (k < SKF_AD_OFF)
+ ptr = load_pointer(skb, k);
+ else
+ break;
+
if (ptr != NULL) {
A = *(u8 *)ptr;
continue;
@@ -217,7 +223,9 @@ load_b:
k = X + fentry->k;
goto load_b;
case BPF_LDX|BPF_B|BPF_MSH:
- ptr = load_pointer(skb, fentry->k, 1, &tmp);
+ if (fentry->k < 0)
+ return 0;
+ ptr = skb_header_pointer(skb, fentry->k, 1, &tmp);
if (ptr != NULL) {
X = (*(u8 *)ptr & 0xf) << 2;
continue;
-
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