sctp: Add ip option support

Add ip option support to allow LSM security modules to utilise CIPSO/IPv4
and CALIPSO/IPv6 services.

Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 91813e6..02f23ad 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -237,6 +237,45 @@ int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
 	return error;
 }
 
+/* Copy over any ip options */
+static void sctp_v4_copy_ip_options(struct sock *sk, struct sock *newsk)
+{
+	struct inet_sock *newinet, *inet = inet_sk(sk);
+	struct ip_options_rcu *inet_opt, *newopt = NULL;
+
+	newinet = inet_sk(newsk);
+
+	rcu_read_lock();
+	inet_opt = rcu_dereference(inet->inet_opt);
+	if (inet_opt) {
+		newopt = sock_kmalloc(newsk, sizeof(*inet_opt) +
+				      inet_opt->opt.optlen, GFP_ATOMIC);
+		if (newopt)
+			memcpy(newopt, inet_opt, sizeof(*inet_opt) +
+			       inet_opt->opt.optlen);
+		else
+			pr_err("%s: Failed to copy ip options\n", __func__);
+	}
+	RCU_INIT_POINTER(newinet->inet_opt, newopt);
+	rcu_read_unlock();
+}
+
+/* Account for the IP options */
+static int sctp_v4_ip_options_len(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct ip_options_rcu *inet_opt;
+	int len = 0;
+
+	rcu_read_lock();
+	inet_opt = rcu_dereference(inet->inet_opt);
+	if (inet_opt)
+		len = inet_opt->opt.optlen;
+
+	rcu_read_unlock();
+	return len;
+}
+
 /* Initialize a sctp_addr from in incoming skb.  */
 static void sctp_v4_from_skb(union sctp_addr *addr, struct sk_buff *skb,
 			     int is_saddr)
@@ -588,6 +627,8 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 	sctp_copy_sock(newsk, sk, asoc);
 	sock_reset_flag(newsk, SOCK_ZAPPED);
 
+	sctp_v4_copy_ip_options(sk, newsk);
+
 	newinet = inet_sk(newsk);
 
 	newinet->inet_daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
@@ -1006,6 +1047,7 @@ static struct sctp_pf sctp_pf_inet = {
 	.addr_to_user  = sctp_v4_addr_to_user,
 	.to_sk_saddr   = sctp_v4_to_sk_saddr,
 	.to_sk_daddr   = sctp_v4_to_sk_daddr,
+	.copy_ip_options = sctp_v4_copy_ip_options,
 	.af            = &sctp_af_inet
 };
 
@@ -1090,6 +1132,7 @@ static struct sctp_af sctp_af_inet = {
 	.ecn_capable	   = sctp_v4_ecn_capable,
 	.net_header_len	   = sizeof(struct iphdr),
 	.sockaddr_len	   = sizeof(struct sockaddr_in),
+	.ip_options_len	   = sctp_v4_ip_options_len,
 #ifdef CONFIG_COMPAT
 	.compat_setsockopt = compat_ip_setsockopt,
 	.compat_getsockopt = compat_ip_getsockopt,