linux-kernel - Re: poll problem with PF_PACKET when using PACKET_RX

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-next>] [day] [month] [year] [list]

Message-ID: <20061015181059.8920.qmail@web50601.mail.yahoo.com>
Date:	Sun, 15 Oct 2006 11:10:59 -0700 (PDT)
From:	Joan Raventos <jraventos@...oo.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	linux-kernel@...r.kernel.org,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: poll problem with PF_PACKET when using PACKET_RX_RING

Hi Patrick,

Thx for your prompt reply! Plz see some comments inline.

>> 
>> Is this a bug in PF_PACKET? Should the socket queue be
>> emptied by packet_set_ring (called via setsockopt when
>> PACKET_RX_RING is used) so the above cannot happen?
>> Should the user-space app drain the socket queue with
>> recvfrom prior to (4) -quite unlikely in practice-?

> I guess the best way is not to bind the socket before having
> completed setup. We could still flush the queue to make life
> easier for userspace, not sure about that ..

Even w/o bind, packet_create is doing a dev_add_pack, which I think will make pkts arrive to that socket (ie. in netif_receive_skb one can see the loops over the rcu for both ptype_all and type-specific which seem match whenever !ptype->dev || ptype->dev==skb->dev).

Also the packet_mmap.txt doc does not mention bind, which probably is more a mechanism to closely specify a dev than to signal socket readiness.

Salu2,
J.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/