Subject: [PATCH 30/43] net: Only honor ifindex in IP_PKTINFO if non-0

From: David Ahern <[email-masked]>
Date: Fri, 16 Feb 2018 11:03:03 -0800

[ Upstream commit 2cbb4ea7de167b02ffa63e9cdfdb07a7e7094615 ]

Only allow ifindex from IP_PKTINFO to override SO_BINDTODEVICE settings
if the index is actually set in the message.

Signed-off-by: David Ahern <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv4/ip_sockglue.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index f56aab54e0c8..1e70ed5244ea 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -258,7 +258,8 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 			src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);
 			if (!ipv6_addr_v4mapped(&src_info->ipi6_addr))
 				return -EINVAL;
-			ipc->oif = src_info->ipi6_ifindex;
+			if (src_info->ipi6_ifindex)
+				ipc->oif = src_info->ipi6_ifindex;
 			ipc->addr = src_info->ipi6_addr.s6_addr32[3];
 			continue;
 		}
@@ -288,7 +289,8 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc,
 			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct in_pktinfo)))
 				return -EINVAL;
 			info = (struct in_pktinfo *)CMSG_DATA(cmsg);
-			ipc->oif = info->ipi_ifindex;
+			if (info->ipi_ifindex)
+				ipc->oif = info->ipi_ifindex;
 			ipc->addr = info->ipi_spec_dst.s_addr;
 			break;
 		}
-- 
2.14.3