1 files changed, 26 insertions, 8 deletions

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 57e1405e8282..ebd953bc5607 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -116,10 +116,10 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
 	if (skb->ip_summed != CHECKSUM_COMPLETE)
 		return;
 
-	if (offset != 0)
-		csum = csum_sub(csum,
-				csum_partial(skb_transport_header(skb) + tlen,
-					     offset, 0));
+	if (offset != 0) {
+		int tend_off = skb_transport_offset(skb) + tlen;
+		csum = csum_sub(csum, skb_checksum(skb, tend_off, offset, 0));
+	}
 
 	put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum);
 }
@@ -272,7 +272,7 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 			continue;
 		switch (cmsg->cmsg_type) {
 		case IP_RETOPTS:
-			err = cmsg->cmsg_len - CMSG_ALIGN(sizeof(struct cmsghdr));
+			err = cmsg->cmsg_len - sizeof(struct cmsghdr);
 
 			/* Our caller is responsible for freeing ipc->opt */
 			err = ip_options_get(net, &ipc->opt, CMSG_DATA(cmsg),
@@ -843,6 +843,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 	{
 		struct ip_mreqn mreq;
 		struct net_device *dev = NULL;
+		int midx;
 
 		if (sk->sk_type == SOCK_STREAM)
 			goto e_inval;
@@ -887,11 +888,15 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 		err = -EADDRNOTAVAIL;
 		if (!dev)
 			break;
+
+		midx = l3mdev_master_ifindex(dev);
+
 		dev_put(dev);
 
 		err = -EINVAL;
 		if (sk->sk_bound_dev_if &&
-		    mreq.imr_ifindex != sk->sk_bound_dev_if)
+		    mreq.imr_ifindex != sk->sk_bound_dev_if &&
+		    (!midx || midx != sk->sk_bound_dev_if))
 			break;
 
 		inet->mc_index = mreq.imr_ifindex;
@@ -1225,14 +1230,27 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
 		 * which has interface index (iif) as the first member of the
 		 * underlying inet{6}_skb_parm struct. This code then overlays
 		 * PKTINFO_SKB_CB and in_pktinfo also has iif as the first
-		 * element so the iif is picked up from the prior IPCB
+		 * element so the iif is picked up from the prior IPCB. If iif
+		 * is the loopback interface, then return the sending interface
+		 * (e.g., process binds socket to eth0 for Tx which is
+		 * redirected to loopback in the rtable/dst).
 		 */
+		if (pktinfo->ipi_ifindex == LOOPBACK_IFINDEX)
+			pktinfo->ipi_ifindex = inet_iif(skb);
+
 		pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
 	} else {
 		pktinfo->ipi_ifindex = 0;
 		pktinfo->ipi_spec_dst.s_addr = 0;
 	}
-	skb_dst_drop(skb);
+	/* We need to keep the dst for __ip_options_echo()
+	 * We could restrict the test to opt.ts_needtime || opt.srr,
+	 * but the following is good enough as IP options are not often used.
+	 */
+	if (unlikely(IPCB(skb)->opt.optlen))
+		skb_dst_force(skb);
+	else
+		skb_dst_drop(skb);
 }
 
 int ip_setsockopt(struct sock *sk, int level,