[PATCH 4.14 12/35] Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"

[Greg Kroah-Hartman]

From: Hangbin Liu <liuhang...@gmail.com>

[ Upstream commit 4970b42d5c362bf873982db7d93245c5281e58f4 ]

This reverts commit e9919a24d3022f72bcadc407e73a6ef17093a849.

Nathan reported the new behaviour breaks Android, as Android just add
new rules and delete old ones.

If we return 0 without adding dup rules, Android will remove the new
added rules and causing system to soft-reboot.

Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule 
exists when NLM_F_EXCL not supplied")
Reported-by: Nathan Chancellor <natechancel...@gmail.com>
Reported-by: Yaro Slav <yaro...@gmail.com>
Reported-by: Maciej Żenczykowski <zenczykow...@gmail.com>
Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
Reviewed-by: Nathan Chancellor <natechancel...@gmail.com>
Tested-by: Nathan Chancellor <natechancel...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/core/fib_rules.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -563,9 +563,9 @@ int fib_nl_newrule(struct sk_buff *skb,
                rule->uid_range = fib_kuid_range_unset;
        }
 
-       if (rule_exists(ops, frh, tb, rule)) {
-               if (nlh->nlmsg_flags & NLM_F_EXCL)
-                       err = -EEXIST;
+       if ((nlh->nlmsg_flags & NLM_F_EXCL) &&
+           rule_exists(ops, frh, tb, rule)) {
+               err = -EEXIST;
                goto errout_free;
        }