net: Only honor ifindex in IP_PKTINFO if non-0

[ Upstream commit 1cbec07649ec8c267cdfb486ab4ee73949974ca4 ]

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 <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 67c1333422a46de7fb048906c40f0abe7959c4f2..d4bdeed4e0a4c9d2c72c0528037f21a254675b2e 100644 (file)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -239,7 +239,8 @@ int ip_cmsg_send(struct net *net, 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;
                }
@@ -262,7 +263,8 @@ int ip_cmsg_send(struct net *net, 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;
                }