[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.
[ Combined with patch from Gerrit Renker to remove two now unnecessary
memsets of IPCB(skb)->opt ]
Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 287a62b..ba2ef94 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -325,6 +325,12 @@
* 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/ipv4.c b/net/dccp/ipv4.c
index 474075a..b337044 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -489,7 +489,6 @@
dh->dccph_checksum = dccp_v4_csum_finish(skb, ireq->loc_addr,
ireq->rmt_addr);
- memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
ireq->rmt_addr,
ireq->opt);
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 3b763db..3d7d628 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -126,7 +126,6 @@
DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
- memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
err = icsk->icsk_af_ops->queue_xmit(skb, 0);
return net_xmit_eval(err);
}
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 @@
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,