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

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

[Hangbin Liu]

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.

Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 net/core/fib_rules.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 43f0115cce9c..18f8dd8329ed 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -757,9 +757,9 @@ int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		goto errout;
 
-	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;
 	}
 
-- 
2.19.2

Re: [PATCH net] Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"

[Nathan Chancellor]

On Wed, Jun 05, 2019 at 12:27:14PM +0800, Hangbin Liu wrote:
> 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.
> 
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied")
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>

I verified a revert on my OP6 when I initially ran into this issue.

Thanks for this. I would recommend that Yaro and Maciej also be given
reported by credit as I am not the only one to bring this up :)

Cheers,
Nathan

Re: [PATCH net] Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"

[David Miller]

From: Hangbin Liu <liuhangbin@gmail.com>
Date: Wed,  5 Jun 2019 12:27:14 +0800

> 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.
> 
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied")
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>

Applied.

Re: [PATCH net] Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"

[Nathan Chancellor]

On Wed, Jun 05, 2019 at 05:55:26PM -0700, David Miller wrote:
> From: Hangbin Liu <liuhangbin@gmail.com>
> Date: Wed,  5 Jun 2019 12:27:14 +0800
> 
> > 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.
> > 
> > Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> > Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied")
> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> 
> Applied.

Please ensure this gets queued up for stable, as that is where I noticed
the issue.

Thank you for applying it,
Nathan

Re: [PATCH net] Revert "fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied"

[David Miller]

From: Nathan Chancellor <natechancellor@gmail.com>
Date: Wed, 5 Jun 2019 18:23:51 -0700

> On Wed, Jun 05, 2019 at 05:55:26PM -0700, David Miller wrote:
>> From: Hangbin Liu <liuhangbin@gmail.com>
>> Date: Wed,  5 Jun 2019 12:27:14 +0800
>> 
>> > 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.
>> > 
>> > Reported-by: Nathan Chancellor <natechancellor@gmail.com>
>> > Fixes: e9919a24d302 ("fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied")
>> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
>> 
>> Applied.
> 
> Please ensure this gets queued up for stable, as that is where I noticed
> the issue.

It is queued up, thanks for asking.

I'll try to get this propagated as soon as possible.

Thanks again.