fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied
authorHangbin Liu <liuhangbin@gmail.com>
Tue, 7 May 2019 09:11:18 +0000 (17:11 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 16 May 2019 17:43:45 +0000 (19:43 +0200)
commit1fff19a925e524556e85efcd728efad5274ce5b6
tree1b7f6b0cc96d8a041cd4df514128dc536db2609f
parentaca669b8383edf47cfa1ac64014673b74bf7fbde
fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied

[ Upstream commit e9919a24d3022f72bcadc407e73a6ef17093a849 ]

With commit 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to
fib_nl_newrule") we now able to check if a rule already exists. But this
only works with iproute2. For other tools like libnl, NetworkManager,
it still could add duplicate rules with only NLM_F_CREATE flag, like

[localhost ~ ]# ip rule
0:      from all lookup local
32766:  from all lookup main
32767:  from all lookup default
100000: from 192.168.7.5 lookup 5
100000: from 192.168.7.5 lookup 5

As it doesn't make sense to create two duplicate rules, let's just return
0 if the rule exists.

Fixes: 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to fib_nl_newrule")
Reported-by: Thomas Haller <thaller@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/core/fib_rules.c