ip_route_me_harder is not considering the L3 domain and sending lookups
to the wrong table. For example consider the following output rule:
iptables -I OUTPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
using perf to analyze lookups via the fib_table_lookup tracepoint shows:
vrf-test 1187 [001] 46887.295927: fib:fib_table_lookup: table 255 oif 0 iif 0
src 0.0.0.0 dst 10.100.1.254 tos 0 scope 0 flags 0
ffffffff8143922c perf_trace_fib_table_lookup ([kernel.kallsyms])
ffffffff81493aac fib_table_lookup ([kernel.kallsyms])
ffffffff8148dda3 __inet_dev_addr_type ([kernel.kallsyms])
ffffffff8148ddf6 inet_addr_type ([kernel.kallsyms])
ffffffff8149e344 ip_route_me_harder ([kernel.kallsyms])
and
vrf-test 1187 [001] 46887.295933: fib:fib_table_lookup: table 255 oif 0 iif 1
src 10.100.1.254 dst 10.100.1.2 tos 0 scope 0 flags
ffffffff8143922c perf_trace_fib_table_lookup ([kernel.kallsyms])
ffffffff81493aac fib_table_lookup ([kernel.kallsyms])
ffffffff814998ff fib4_rule_action ([kernel.kallsyms])
ffffffff81437f35 fib_rules_lookup ([kernel.kallsyms])
ffffffff81499758 __fib_lookup ([kernel.kallsyms])
ffffffff8144f010 fib_lookup.constprop.34 ([kernel.kallsyms])
ffffffff8144f759 __ip_route_output_key_hash ([kernel.kallsyms])
ffffffff8144fc6a ip_route_output_flow ([kernel.kallsyms])
ffffffff8149e39b ip_route_me_harder ([kernel.kallsyms])
Updating both lookups to pull the L3 domain from the dst currently
attached to the skb directs both lookups to the correct table.
Signed-off-by: David Ahern <d...@cumulusnetworks.com>
---
Pablo: from a code review it seems ip_route_me_harder is only called in
the output path and after skb_dst is set.
net/ipv4/netfilter.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index c3776ff6749f..b3cc1335adbc 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -24,10 +24,11 @@ int ip_route_me_harder(struct net *net, struct sk_buff
*skb, unsigned int addr_t
struct flowi4 fl4 = {};
__be32 saddr = iph->saddr;
__u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
+ struct net_device *dev = skb_dst(skb)->dev;
unsigned int hh_len;
if (addr_type == RTN_UNSPEC)
- addr_type = inet_addr_type(net, saddr);
+ addr_type = inet_addr_type_dev_table(net, dev, saddr);
if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
flags |= FLOWI_FLAG_ANYSRC;
else
@@ -40,6 +41,8 @@ int ip_route_me_harder(struct net *net, struct sk_buff *skb,
unsigned int addr_t
fl4.saddr = saddr;
fl4.flowi4_tos = RT_TOS(iph->tos);
fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
+ if (!fl4.flowi4_oif)
+ fl4.flowi4_oif = l3mdev_master_ifindex(dev);
fl4.flowi4_mark = skb->mark;
fl4.flowi4_flags = flags;
rt = ip_route_output_key(net, &fl4);
--
2.1.4
