queue-4.9/fib_rules-return-0-directly-if-an-exactly-same-rule-exists-when-nlm_f_excl-not-supplied.patch

   1 From foo@baz Wed 15 May 2019 09:45:15 AM CEST
   2 From: Hangbin Liu <liuhangbin@gmail.com>
   3 Date: Tue, 7 May 2019 17:11:18 +0800
   4 Subject: fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied
   5
   6 From: Hangbin Liu <liuhangbin@gmail.com>
   7
   8 [ Upstream commit e9919a24d3022f72bcadc407e73a6ef17093a849 ]
   9
  10 With commit 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to
  11 fib_nl_newrule") we now able to check if a rule already exists. But this
  12 only works with iproute2. For other tools like libnl, NetworkManager,
  13 it still could add duplicate rules with only NLM_F_CREATE flag, like
  14
  15 [localhost ~ ]# ip rule
  16 0:      from all lookup local
  17 32766:  from all lookup main
  18 32767:  from all lookup default
  19 100000: from 192.168.7.5 lookup 5
  20 100000: from 192.168.7.5 lookup 5
  21
  22 As it doesn't make sense to create two duplicate rules, let's just return
  23 0 if the rule exists.
  24
  25 Fixes: 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to fib_nl_newrule")
  26 Reported-by: Thomas Haller <thaller@redhat.com>
  27 Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
  28 Signed-off-by: David S. Miller <davem@davemloft.net>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30 ---
  31  net/core/fib_rules.c |    6 +++---
  32  1 file changed, 3 insertions(+), 3 deletions(-)
  33
  34 --- a/net/core/fib_rules.c
  35 +++ b/net/core/fib_rules.c
  36 @@ -429,9 +429,9 @@ int fib_nl_newrule(struct sk_buff *skb,
  37         if (rule->l3mdev && rule->table)
  38                 goto errout_free;
  39
  40 -       if ((nlh->nlmsg_flags & NLM_F_EXCL) &&
  41 -           rule_exists(ops, frh, tb, rule)) {
  42 -               err = -EEXIST;
  43 +       if (rule_exists(ops, frh, tb, rule)) {
  44 +               if (nlh->nlmsg_flags & NLM_F_EXCL)
  45 +                       err = -EEXIST;
  46                 goto errout_free;
  47         }
  48