linux-kernel - Re: Fix signalfd interaction with thread-private signals

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: <20070622160405.GA189@tv-sign.ru>
Date:	Fri, 22 Jun 2007 20:04:06 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Davide Libenzi <davidel@...ilserver.org>,
	Nicholas Miell <nmiell@...cast.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Fix signalfd interaction with thread-private signals

On 06/22, Benjamin Herrenschmidt wrote:
> 
> That is, it -does- make sense to be able to create a signal singalfd in
> a process and have N threads reading from it and getting either shared
> signals or their local private signals.

Great.

> I just don't like the actual implementation of it by changing the task
> pointer on the fly...
>
> My main issue is a matter of consistency of the signalfd API as a
> whole... the whole bloody thing is instanciated & attached to a thread
> in the first place. Maybe we should change that and say that one
> instanciates a signalfd on a thread group... that is, it always gets
> attached to the leader.

It does exactly so, please note this chunk

 @@ -330,7 +339,7 @@ asmlinkage long sys_signalfd(int ufd, si

                 init_waitqueue_head(&ctx->wqh);
                 ctx->sigmask = sigmask;
 -               ctx->tsk = current;
 +               ctx->tsk = current->group_leader;

> It might well be that signalfd's concept of context is wrong in the
> first place and it should be attached to processes rather than threads
> and that made more explicit in the first place...

Exactly!

Oleg.

-
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/