netdev - [RFC PATCH v3 12/19] ipv6: Allow request socks to contain IPv6 options.

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Date:	Wed, 17 Feb 2016 13:22:02 +0000
From:	Huw Davies <huw@...eweavers.com>
To:	netdev@...r.kernel.org, linux-security-module@...r.kernel.org,
	selinux@...ho.nsa.gov
Cc:	Paul Moore <pmoore@...hat.com>
Subject: [RFC PATCH v3 12/19] ipv6: Allow request socks to contain IPv6 options.

If set, these will take precedence over the parent's options during
both sending and child creation.  If they're not set, the parent's
options (if any) will be used.

This is to allow the security_inet_conn_request() hook to modify the
IPv6 options in just the same way that it already may do for IPv4.

Signed-off-by: Huw Davies <huw@...eweavers.com>
---
 include/net/inet_sock.h |  7 ++++++-
 net/dccp/ipv6.c         | 12 +++++++++---
 net/ipv4/tcp_input.c    |  3 +++
 net/ipv6/tcp_ipv6.c     | 12 +++++++++---
 4 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 012b1f9..236a810 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -97,7 +97,12 @@ struct inet_request_sock {
 	u32                     ir_mark;
 	union {
 		struct ip_options_rcu	*opt;
-		struct sk_buff		*pktopts;
+#if IS_ENABLED(CONFIG_IPV6)
+		struct {
+			struct ipv6_txoptions	*ipv6_opt;
+			struct sk_buff		*pktopts;
+		};
+#endif
 	};
 };
 
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 9c6d050..8bb1c3a 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -216,14 +216,17 @@ static int dccp_v6_send_response(const struct sock *sk, struct request_sock *req
 	skb = dccp_make_response(sk, dst, req);
 	if (skb != NULL) {
 		struct dccp_hdr *dh = dccp_hdr(skb);
+		struct ipv6_txoptions *opt;
 
 		dh->dccph_checksum = dccp_v6_csum_finish(skb,
 							 &ireq->ir_v6_loc_addr,
 							 &ireq->ir_v6_rmt_addr);
 		fl6.daddr = ireq->ir_v6_rmt_addr;
 		rcu_read_lock();
-		err = ip6_xmit(sk, skb, &fl6, rcu_dereference(np->opt),
-			       np->tclass);
+		opt = ireq->ipv6_opt;
+		if (!opt)
+			opt = rcu_dereference(np->opt);
+		err = ip6_xmit(sk, skb, &fl6, opt, np->tclass);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
@@ -236,6 +239,7 @@ done:
 static void dccp_v6_reqsk_destructor(struct request_sock *req)
 {
 	dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
+	kfree(inet_rsk(req)->ipv6_opt);
 	kfree_skb(inet_rsk(req)->pktopts);
 }
 
@@ -494,7 +498,9 @@ static struct sock *dccp_v6_request_recv_sock(const struct sock *sk,
 	 * Yes, keeping reference count would be much more clever, but we make
 	 * one more one thing there: reattach optmem to newsk.
 	 */
-	opt = rcu_dereference(np->opt);
+	opt = ireq->ipv6_opt;
+	if (!opt)
+		opt = rcu_dereference(np->opt);
 	if (opt) {
 		opt = ipv6_dup_options(newsk, opt);
 		RCU_INIT_POINTER(newnp->opt, opt);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 1c2a734..f8baa08 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6095,6 +6095,9 @@ struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
 
 		kmemcheck_annotate_bitfield(ireq, flags);
 		ireq->opt = NULL;
+#if IS_ENABLED(CONFIG_IPV6)
+		ireq->pktopts = NULL;
+#endif
 		atomic64_set(&ireq->ir_cookie, 0);
 		ireq->ireq_state = TCP_NEW_SYN_RECV;
 		write_pnet(&ireq->ireq_net, sock_net(sk_listener));
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1a5a70f..6b05a43 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -443,6 +443,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct ipv6_txoptions *opt;
 	struct flowi6 *fl6 = &fl->u.ip6;
 	struct sk_buff *skb;
 	int err = -ENOMEM;
@@ -463,8 +464,10 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
 			fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));
 
 		rcu_read_lock();
-		err = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt),
-			       np->tclass);
+		opt = ireq->ipv6_opt;
+		if (!opt)
+			opt = rcu_dereference(np->opt);
+		err = ip6_xmit(sk, skb, fl6, opt, np->tclass);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
@@ -476,6 +479,7 @@ done:
 
 static void tcp_v6_reqsk_destructor(struct request_sock *req)
 {
+	kfree(inet_rsk(req)->ipv6_opt);
 	kfree_skb(inet_rsk(req)->pktopts);
 }
 
@@ -1103,7 +1107,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 	   but we make one more one thing there: reattach optmem
 	   to newsk.
 	 */
-	opt = rcu_dereference(np->opt);
+	opt = ireq->ipv6_opt;
+	if (!opt)
+		opt = rcu_dereference(np->opt);
 	if (opt) {
 		opt = ipv6_dup_options(newsk, opt);
 		RCU_INIT_POINTER(newnp->opt, opt);
-- 
2.7.0