linux-kernel - Re: Thoughts on credential switching

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]

Date:	Thu, 27 Mar 2014 16:41:27 +0100
From:	Florian Weimer <fweimer@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>,
	Serge Hallyn <serge.hallyn@...ntu.com>
CC:	Jim Lieb <jlieb@...asas.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	LSM List <linux-security-module@...r.kernel.org>,
	"Serge E. Hallyn" <serge@...onical.com>,
	Kees Cook <keescook@...omium.org>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>,
	"Theodore Ts'o" <tytso@....edu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	bfields@...hat.com, Jeff Layton <jlayton@...hat.com>
Subject: Re: Thoughts on credential switching

On 03/27/2014 02:01 AM, Andy Lutomirski wrote:

> Essentially, it's a performance problem.  knfsd has override_creds,
> and it can cache struct cred.  But userspace doing the same thing
> (i.e. impersonating a user) has to do setresuid, setresgid, and
> setgroups, which kills performance, since it results in something like
> five RCU callbacks per impersonation round-trip.

Do you mean setfsuid instead of setresuid?

-- 
Florian Weimer / Red Hat Product Security Team
--
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/