net: relax PKTINFO non local ipv6 udp xmit check

Allow transparent sockets to be less restrictive about
the source ip of ipv6 udp packets being sent.

Google-Bug-Id: 5018138
Signed-off-by: Maciej Żenczykowski <maze@google.com>
CC: "Erik Kline" <ek@google.com>
CC: "Lorenzo Colitti" <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/transp_v6.h

@@ -39,6 +39,7 @@ extern int			datagram_recv_ctl(struct sock *sk,
 						  struct sk_buff *skb);
 
 extern int			datagram_send_ctl(struct net *net,
+						  struct sock *sk,
 						  struct msghdr *msg,
 						  struct flowi6 *fl6,
 						  struct ipv6_txoptions *opt,

net/ipv6/datagram.c

@@ -599,7 +599,7 @@ int datagram_recv_ctl(struct sock *sk, struct msghdr *msg, struct sk_buff *skb)
 	return 0;
 }
 
-int datagram_send_ctl(struct net *net,
+int datagram_send_ctl(struct net *net, struct sock *sk,
 		      struct msghdr *msg, struct flowi6 *fl6,
 		      struct ipv6_txoptions *opt,
 		      int *hlimit, int *tclass, int *dontfrag)
@@ -658,7 +658,8 @@ int datagram_send_ctl(struct net *net,
 
 			if (addr_type != IPV6_ADDR_ANY) {
 				int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
-				if (!ipv6_chk_addr(net, &src_info->ipi6_addr,
+				if (!inet_sk(sk)->transparent &&
+				    !ipv6_chk_addr(net, &src_info->ipi6_addr,
 						   strict ? dev : NULL, 0))
 					err = -EINVAL;
 				else

net/ipv6/ip6_flowlabel.c

@@ -322,8 +322,8 @@ static int fl6_renew(struct ip6_flowlabel *fl, unsigned long linger, unsigned lo
 }
 
 static struct ip6_flowlabel *
-fl_create(struct net *net, struct in6_flowlabel_req *freq, char __user *optval,
-	  int optlen, int *err_p)
+fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq,
+	  char __user *optval, int optlen, int *err_p)
 {
 	struct ip6_flowlabel *fl = NULL;
 	int olen;
@@ -360,7 +360,7 @@ fl_create(struct net *net, struct in6_flowlabel_req *freq, char __user *optval,
 		msg.msg_control = (void*)(fl->opt+1);
 		memset(&flowi6, 0, sizeof(flowi6));
 
-		err = datagram_send_ctl(net, &msg, &flowi6, fl->opt, &junk,
+		err = datagram_send_ctl(net, sk, &msg, &flowi6, fl->opt, &junk,
 					&junk, &junk);
 		if (err)
 			goto done;
@@ -528,7 +528,7 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 		if (freq.flr_label & ~IPV6_FLOWLABEL_MASK)
 			return -EINVAL;
 
-		fl = fl_create(net, &freq, optval, optlen, &err);
+		fl = fl_create(net, sk, &freq, optval, optlen, &err);
 		if (fl == NULL)
 			return err;
 		sfl1 = kmalloc(sizeof(*sfl1), GFP_KERNEL);

net/ipv6/ipv6_sockglue.c

@@ -475,7 +475,7 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		msg.msg_controllen = optlen;
 		msg.msg_control = (void*)(opt+1);
 
-		retv = datagram_send_ctl(net, &msg, &fl6, opt, &junk, &junk,
+		retv = datagram_send_ctl(net, sk, &msg, &fl6, opt, &junk, &junk,
 					 &junk);
 		if (retv)
 			goto done;

net/ipv6/raw.c

@@ -817,8 +817,8 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk,
 		memset(opt, 0, sizeof(struct ipv6_txoptions));
 		opt->tot_len = sizeof(struct ipv6_txoptions);
 
-		err = datagram_send_ctl(sock_net(sk), msg, &fl6, opt, &hlimit,
-					&tclass, &dontfrag);
+		err = datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
+					&hlimit, &tclass, &dontfrag);
 		if (err < 0) {
 			fl6_sock_release(flowlabel);
 			return err;

net/ipv6/udp.c

@@ -1090,8 +1090,8 @@ int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
 		memset(opt, 0, sizeof(struct ipv6_txoptions));
 		opt->tot_len = sizeof(*opt);
 
-		err = datagram_send_ctl(sock_net(sk), msg, &fl6, opt, &hlimit,
-					&tclass, &dontfrag);
+		err = datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
+					&hlimit, &tclass, &dontfrag);
 		if (err < 0) {
 			fl6_sock_release(flowlabel);
 			return err;