netdev - Re: [PATCH] net: check net.core.somaxconn sysctl values

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <51F9273B.2020408@yandex-team.ru>
Date:	Wed, 31 Jul 2013 19:03:23 +0400
From:	Roman Gushchin <klamm@...dex-team.ru>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	"David S. Miller" <davem@...emloft.net>, raise.sail@...il.com,
	ebiederm@...ssion.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values

On 31.07.2013 18:37, Eric Dumazet wrote:
> On Wed, 2013-07-31 at 17:57 +0400, Roman Gushchin wrote:
>> It's possible to assign an invalid value to the net.core.somaxconn
>> sysctl variable, because there is no checks at all.
>>
>> The sk_max_ack_backlog field of the sock structure is defined as
>> unsigned short. Therefore, the backlog argument in inet_listen()
>> shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall
>> is truncated to the somaxconn value. So, the somaxconn value shouldn't
>> exceed 65535 (USHRT_MAX).
>> Also, negative values of somaxconn are meaningless.
>>
>> before:
>> $ sysctl -w net.core.somaxconn=256
>> net.core.somaxconn = 256
>> $ sysctl -w net.core.somaxconn=65536
>> net.core.somaxconn = 65536
>> $ sysctl -w net.core.somaxconn=-100
>> net.core.somaxconn = -100
>>
>> after:
>> $ sysctl -w net.core.somaxconn=256
>> net.core.somaxconn = 256
>> $ sysctl -w net.core.somaxconn=65536
>> error: "Invalid argument" setting key "net.core.somaxconn"
>> $ sysctl -w net.core.somaxconn=-100
>> error: "Invalid argument" setting key "net.core.somaxconn"
>>
>> Signed-off-by: Roman Gushchin <klamm@...dex-team.ru>
>> ---
>>    net/core/sysctl_net_core.c | 6 +++++-
>>    1 file changed, 5 insertions(+), 1 deletion(-)
>
>
> We had a discussion about this one month ago, as Changli Gao posted a
> patch. http://patchwork.ozlabs.org/patch/255460/
>
> So proper credits would be nice ;)

Ok :)

> Based on a prior patch from Changli Gao
>
> Reported-by: Changli Gao <xiaosuo@...il.com>
> Suggested-by: Eric Dumazet <edumazet@...gle.com>
>
> Acked-by: Eric Dumazet <edumazet@...gle.com>
>

Thanks!

PS I've forwarded your letter back to the lkml by mistake.
Sorry)

Regards,
Roman

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html