Commit d03a4557 authored Dec 19, 2017 by Phil Sutter Committed by David S. Miller Dec 19, 2017

ipv4: fib: Fix metrics match when deleting a route



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: 5f9ae3d9 ("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>

parent a1762456

net/ipv4/fib_semantics.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -698,7 +698,7 @@ bool fib_metrics_match(struct fib_config cfg, struct fib_info fi)

		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;
		@@ -715,7 +715,11 @@ bool fib_metrics_match(struct fib_config cfg, struct fib_info fi)
		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;
		}

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