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iproute2: fix MPLS label parsing 

The initial value of "label" in parse_mpls() is 0xffffffff. Therefore
we should test for this value, and not 0, to detect if a label has been
provided. The "!label" test not only fails to detect a missing label
parameter, it also prevents the use of the IPv4 explicit NULL label,
which actually equals 0.

Reproducer:
  $ ip link add name dm0 type dummy
  $ tc qdisc add dev dm0 ingress

  $ tc filter add dev dm0 parent ffff: matchall action mpls push
  Error: act_mpls: Label is required for MPLS push.
  We have an error talking to the kernel
  --> Filter was pushed to the kernel, where it got rejected.

  $ tc filter add dev dm0 parent ffff: matchall action mpls push label 0
  Error: argument "label" is required
  --> Label 0 was rejected by iproute2.

Expected result:
  $ tc filter add dev dm0 parent ffff: matchall action mpls push
  Error: argument "label" is required
  --> Filter was directly rejected by iproute2.

  $ tc filter add dev dm0 parent ffff: matchall action mpls push label 0
  --> Filter is accepted.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Guillaume Nault 2020-03-11 16:16:36 +01:00 committed by Stephen Hemminger
parent d9b868436a
commit 72cc0bafb9
1 changed files with 1 additions and 1 deletions
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2
tc/m_mpls.c
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@ -156,7 +156,7 @@ static int parse_mpls(struct action_util *a, int *argc_p, char ***argv_p,
}
}
if (action == TCA_MPLS_ACT_PUSH && !label)
if (action == TCA_MPLS_ACT_PUSH && label == 0xffffffff)
missarg("label");
if (action == TCA_MPLS_ACT_PUSH && proto &&