[PATCH iproute2 net-next] tc: m_mirred: Fix parsing of 'index' optional argument

[PATCH iproute2 net-next] tc: m_mirred: Fix parsing of 'index' optional argument

[Shmulik Ladkani]

Code in parse_mirred() suggests "index" argument can be placed either
after the "egress" clause, or as the first argument (after "action mirred").

However, parse_egress() fails to correctly parse "index" if it's the
first argument.

For example:

 # tc filter add ... action mirred index 5
 RTNETLINK answers: Invalid argument
 (unnecessary RTNETLINK issued, should have been parse error)

 # tc filter add ... action mirred index 5 egress redirect dev eth0
 bad action type egress
 (should have been parsed successfully)

Fix parse_egress as follows:
 - continue parsing after valid "index" is seen
 - don't issue the RTNETLINK unless valid "egress" is seen

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
---

 Well, both man and usage suggest "index" comes after the egress clause:
    tc ... action mirred DIRECTION ACTION [ index INDEX ] dev DEVICENAME
 So an alternative would be banning "index" as 1st argument in parse_mirred.

 tc/m_mirred.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/tc/m_mirred.c b/tc/m_mirred.c
index 11f4c9b46f..d3e750b89b 100644
--- a/tc/m_mirred.c
+++ b/tc/m_mirred.c
@@ -91,9 +91,8 @@ parse_egress(struct action_util *a, int *argc_p, char ***argv_p,
 				}
 				iok++;
 				if (!ok) {
-					argc--;
-					argv++;
-					break;
+					NEXT_ARG();
+					continue;
 				}
 			} else if (!ok) {
 				fprintf(stderr, "was expecting egress (%s)\n", *argv);
@@ -134,7 +133,7 @@ parse_egress(struct action_util *a, int *argc_p, char ***argv_p,
 		NEXT_ARG();
 	}
 
-	if (!ok && !iok) {
+	if (!ok) {
 		return -1;
 	}
 
-- 
2.7.4

Re: [PATCH iproute2 net-next] tc: m_mirred: Fix parsing of 'index' optional argument

[Stephen Hemminger]

On Fri, 21 Oct 2016 23:01:15 +0300
Shmulik Ladkani <shmulik.ladkani@gmail.com> wrote:

> Code in parse_mirred() suggests "index" argument can be placed either
> after the "egress" clause, or as the first argument (after "action mirred").
> 
> However, parse_egress() fails to correctly parse "index" if it's the
> first argument.
> 
> For example:
> 
>  # tc filter add ... action mirred index 5
>  RTNETLINK answers: Invalid argument
>  (unnecessary RTNETLINK issued, should have been parse error)
> 
>  # tc filter add ... action mirred index 5 egress redirect dev eth0
>  bad action type egress
>  (should have been parsed successfully)
> 
> Fix parse_egress as follows:
>  - continue parsing after valid "index" is seen
>  - don't issue the RTNETLINK unless valid "egress" is seen
> 
> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>

Looks like a good fix but does not apply cleanly to current net-next branch.

Please cleanup and resubmit.