Arnaldo Carvalho de Melo wrote:
Em Fri, Apr 04, 2008 at 02:13:16PM +0200, Patrick McHardy escreveu:
commit eced67957ee99f7b5fafdc73a58bcd037a1789b2
Author: Patrick McHardy <kaber@xxxxxxxxx>
Date: Fri Apr 4 14:10:23 2008 +0200
[DCCP]: Fix skb->cb conflicts with IP
dev_queue_xmit() and the other IP output functions expect to get a skb
with clear or properly initialized skb->cb. Unlike TCP and UDP, the
dccp_skb_cb doesn't contain a struct inet_skb_parm at the beginning,
so the DCCP-specific data is interpreted by the IP output functions.
This can cause false negatives for the conditional POST_ROUTING hook
invocation, making the packet bypass the hook.
Add a inet_skb_parm/inet6_skb_parm union to the beginning of
dccp_skb_cb to avoid clashes. Also add a BUILD_BUG_ON to make
sure it fits in the cb.
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
Thanks Patrick,
Acked-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Dave, I'm not sure whether you've missed this or expect it
to go through Arnaldo, just want to make sure it doesn't
get missed because of a misunderstanding :)
commit eced67957ee99f7b5fafdc73a58bcd037a1789b2
Author: Patrick McHardy <kaber@xxxxxxxxx>
Date: Fri Apr 4 14:10:23 2008 +0200
[DCCP]: Fix skb->cb conflicts with IP
dev_queue_xmit() and the other IP output functions expect to get a skb
with clear or properly initialized skb->cb. Unlike TCP and UDP, the
dccp_skb_cb doesn't contain a struct inet_skb_parm at the beginning,
so the DCCP-specific data is interpreted by the IP output functions.
This can cause false negatives for the conditional POST_ROUTING hook
invocation, making the packet bypass the hook.
Add a inet_skb_parm/inet6_skb_parm union to the beginning of
dccp_skb_cb to avoid clashes. Also add a BUILD_BUG_ON to make
sure it fits in the cb.
Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index fe7726b..f44d492 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -325,6 +325,12 @@ static inline int dccp_bad_service_code(const struct sock *sk,
* This is used for transmission as well as for reception.
*/
struct dccp_skb_cb {
+ union {
+ struct inet_skb_parm h4;
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+ struct inet6_skb_parm h6;
+#endif
+ } header;
__u8 dccpd_type:4;
__u8 dccpd_ccval:4;
__u8 dccpd_reset_code,
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index e3f5d37..c91d3c1 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -1057,6 +1057,9 @@ static int __init dccp_init(void)
int ehash_order, bhash_order, i;
int rc = -ENOBUFS;
+ BUILD_BUG_ON(sizeof(struct dccp_skb_cb) >
+ FIELD_SIZEOF(struct sk_buff, cb));
+
dccp_hashinfo.bind_bucket_cachep =
kmem_cache_create("dccp_bind_bucket",
sizeof(struct inet_bind_bucket), 0,
