path: root/net/ipv4/route.c
diff options
authorIdo Schimmel <idosch@mellanox.com>2018-12-20 17:03:27 +0000
committerDavid S. Miller <davem@davemloft.net>2018-12-20 16:42:39 -0800
commit21f9477537059344e4705719137f6695de93b662 (patch)
tree448b5a47c5c8c3027dd972a402bd8887522693de /net/ipv4/route.c
parentnet: mscc: ocelot: Register poll timeout should be wall time not attempts (diff)
net: ipv4: Set skb->dev for output route resolution
When user requests to resolve an output route, the kernel synthesizes an skb where the relevant parameters (e.g., source address) are set. The skb is then passed to ip_route_output_key_hash_rcu() which might call into the flow dissector in case a multipath route was hit and a nexthop needs to be selected based on the multipath hash. Since both 'skb->dev' and 'skb->sk' are not set, a warning is triggered in the flow dissector [1]. The warning is there to prevent codepaths from silently falling back to the standard flow dissector instead of the BPF one. Therefore, instead of removing the warning, set 'skb->dev' to the loopback device, as its not used for anything but resolving the correct namespace. [1] WARNING: CPU: 1 PID: 24819 at net/core/flow_dissector.c:764 __skb_flow_dissect+0x314/0x16b0 ... RSP: 0018:ffffa0df41fdf650 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8bcded232000 RCX: 0000000000000000 RDX: ffffa0df41fdf7e0 RSI: ffffffff98e415a0 RDI: ffff8bcded232000 RBP: ffffa0df41fdf760 R08: 0000000000000000 R09: 0000000000000000 R10: ffffa0df41fdf7e8 R11: ffff8bcdf27a3000 R12: ffffffff98e415a0 R13: ffffa0df41fdf7e0 R14: ffffffff98dd2980 R15: ffffa0df41fdf7e0 FS: 00007f46f6897680(0000) GS:ffff8bcdf7a80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055933e95f9a0 CR3: 000000021e636000 CR4: 00000000001006e0 Call Trace: fib_multipath_hash+0x28c/0x2d0 ? fib_multipath_hash+0x28c/0x2d0 fib_select_path+0x241/0x32f ? __fib_lookup+0x6a/0xb0 ip_route_output_key_hash_rcu+0x650/0xa30 ? __alloc_skb+0x9b/0x1d0 inet_rtm_getroute+0x3f7/0xb80 ? __alloc_pages_nodemask+0x11c/0x2c0 rtnetlink_rcv_msg+0x1d9/0x2f0 ? rtnl_calcit.isra.24+0x120/0x120 netlink_rcv_skb+0x54/0x130 rtnetlink_rcv+0x15/0x20 netlink_unicast+0x20a/0x2c0 netlink_sendmsg+0x2d1/0x3d0 sock_sendmsg+0x39/0x50 ___sys_sendmsg+0x2a0/0x2f0 ? filemap_map_pages+0x16b/0x360 ? __handle_mm_fault+0x108e/0x13d0 __sys_sendmsg+0x63/0xa0 ? __sys_sendmsg+0x63/0xa0 __x64_sys_sendmsg+0x1f/0x30 do_syscall_64+0x5a/0x120 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: d0e13a1488ad ("flow_dissector: lookup netns by skb->sk if skb->dev is NULL") Signed-off-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/route.c')
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c4ddbc5f01fc..ce92f73cf104 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2849,6 +2849,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
err = -rt->dst.error;
} else {
fl4.flowi4_iif = LOOPBACK_IFINDEX;
+ skb->dev = net->loopback_dev;
rt = ip_route_output_key_hash_rcu(net, &fl4, &res, skb);
err = 0;
if (IS_ERR(rt))