[PATCH 4.14 111/146] ipv4: fib: Fix metrics match when deleting a route

Greg Kroah-Hartman
2018-01-01T14:48:01Z

From: Phil Sutter <phil@nwl.cc>

[ Upstream commit d03a45572efa068fa64db211d6d45222660e76c5 ]

The recently added fib_metrics_match() causes a regression for routes
with both RTAX_FEATURES and RTAX_CC_ALGO if the latter has
TCP_CONG_NEEDS_ECN flag set:

| # ip link add d0 type dummy
| # ip link set d0 up
| # ip route add 172.29.29.0/24 dev d0 features ecn congctl dctcp
| # ip route del 172.29.29.0/24 dev d0 features ecn congctl dctcp
| RTNETLINK answers: No such process

During route insertion, fib_convert_metrics() detects that the given CC
algo requires ECN and hence sets DST_FEATURE_ECN_CA bit in
RTAX_FEATURES.

During route deletion though, fib_metrics_match() compares stored
RTAX_FEATURES value with that from userspace (which obviously has no
knowledge about DST_FEATURE_ECN_CA) and fails.

Fixes: 5f9ae3d9e7e4a ("ipv4: do metrics match when looking up and deleting a route")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/fib_semantics.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -706,7 +706,7 @@ bool fib_metrics_match(struct fib_config

nla_for_each_attr(nla, cfg->fc_mx, cfg->fc_mx_len, remaining) {
int type = nla_type(nla);
- u32 val;
+ u32 fi_val, val;

if (!type)
continue;
@@ -723,7 +723,11 @@ bool fib_metrics_match(struct fib_config
val = nla_get_u32(nla);
}

- if (fi->fib_metrics->metrics[type - 1] != val)
+ fi_val = fi->fib_metrics->metrics[type - 1];
+ if (type == RTAX_FEATURES)
+ fi_val &= ~DST_FEATURE_ECN_CA;
+
+ if (fi_val != val)
return false;
}