ipv6: constify ip6_xmit() sock argument
This is to document that socket lock might not be held at this point.
skb_set_owner_w() and ipv6_local_error() are using proper atomic ops
or spinlocks, so we promote the socket to non const when calling them.
netfilter hooks should never assume socket lock is held,
we also promote the socket to non const.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 9aadd57..d70b023 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -263,7 +263,7 @@
void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info)
{
- struct ipv6_pinfo *np = inet6_sk(sk);
+ const struct ipv6_pinfo *np = inet6_sk(sk);
struct sock_exterr_skb *serr;
struct ipv6hdr *iph;
struct sk_buff *skb;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 6b0d86f..60c5653 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -150,14 +150,16 @@
}
/*
- * xmit an sk_buff (used by TCP, SCTP and DCCP)
+ * xmit an sk_buff (used by TCP, SCTP and DCCP)
+ * Note : socket lock is not held for SYNACK packets, but might be modified
+ * by calls to skb_set_owner_w() and ipv6_local_error(),
+ * which are using proper atomic operations or spinlocks.
*/
-
-int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
+int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
struct ipv6_txoptions *opt, int tclass)
{
struct net *net = sock_net(sk);
- struct ipv6_pinfo *np = inet6_sk(sk);
+ const struct ipv6_pinfo *np = inet6_sk(sk);
struct in6_addr *first_hop = &fl6->daddr;
struct dst_entry *dst = skb_dst(skb);
struct ipv6hdr *hdr;
@@ -186,7 +188,10 @@
}
consume_skb(skb);
skb = skb2;
- skb_set_owner_w(skb, sk);
+ /* skb_set_owner_w() changes sk->sk_wmem_alloc atomically,
+ * it is safe to call in our context (socket lock not held)
+ */
+ skb_set_owner_w(skb, (struct sock *)sk);
}
if (opt->opt_flen)
ipv6_push_frag_opts(skb, opt, &proto);
@@ -224,13 +229,20 @@
if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {
IP6_UPD_PO_STATS(net, ip6_dst_idev(skb_dst(skb)),
IPSTATS_MIB_OUT, skb->len);
+ /* hooks should never assume socket lock is held.
+ * we promote our socket to non const
+ */
return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
- net, sk, skb, NULL, dst->dev,
+ net, (struct sock *)sk, skb, NULL, dst->dev,
dst_output_okfn);
}
skb->dev = dst->dev;
- ipv6_local_error(sk, EMSGSIZE, fl6, mtu);
+ /* ipv6_local_error() does not require socket lock,
+ * we promote our socket to non const
+ */
+ ipv6_local_error((struct sock *)sk, EMSGSIZE, fl6, mtu);
+
IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_FRAGFAILS);
kfree_skb(skb);
return -EMSGSIZE;