From: Pavel Machek <pavel@ucw.cz>
To: Ernie Petrides <petrides@redhat.com>
Cc: Michael Glasgow <glasgowNOSPAM@beer.net>,
"Theodore Ts'o" <tytso@mit.edu>,
linux-kernel@vger.kernel.org
Subject: Re: posix capabilities inheritance
Date: Sat, 25 Oct 2003 21:51:53 +0200 [thread overview]
Message-ID: <20031025195153.GA505@elf.ucw.cz> (raw)
In-Reply-To: <200310240136.h9O1aaOU002931@pasta.boston.redhat.com>
Hi!
> > The code to drop privs is not hard, but it's also not trivial.
>
> Here's an example code sequence that demonstrates how a setuid-to-root
> application could drop all capabilities except for CAP_IPC_LOCK and
> then run with the non-privileged uid:
>
> #include <sys/prctl.h>
> #include <sys/capability.h>
>
> ...
>
> cap_t c;
>
> if (prctl(PR_SET_KEEPCAPS, 1UL, 0UL, 0UL, 0UL) < 0 ||
> seteuid(getuid()) < 0 ||
> !(c = cap_from_text("cap_ipc_lock=eip")) ||
> cap_set_proc(c) < 0)
> /* handle error */;
>
> However, I agree that it's often not viable to require application
> changes to achieve the desired result.
IIRC, libraries have special startup sections that run before
main(). And c++ constructors do, too; so wrapper still might be safer
option.
Pavel
--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
next prev parent reply other threads:[~2003-10-25 19:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <fa.f4bs2b4.fhub0m@ifi.uio.no>
2003-10-23 22:05 ` Michael Glasgow
2003-10-23 22:59 ` Theodore Ts'o
2003-10-24 1:36 ` Ernie Petrides
2003-10-24 2:19 ` Bernd Eckenfels
2003-10-24 5:10 ` Ernie Petrides
2003-10-25 19:51 ` Pavel Machek [this message]
[not found] <fa.f26d55g.1qgijbi@ifi.uio.no>
[not found] ` <fa.hq0dft9.9i0obd@ifi.uio.no>
2003-10-24 21:24 ` Andy Lutomirski
[not found] <fa.n4rmmgg.2423pm@ifi.uio.no>
[not found] ` <fa.l1oevhb.1s5k583@ifi.uio.no>
2003-10-24 8:44 ` Andy Lutomirski
2003-10-24 12:41 ` Theodore Ts'o
2003-10-24 16:44 ` Andy Lutomirski
2003-10-24 20:58 ` David Wagner
2003-10-23 1:41 Albert Cahalan
[not found] <fa.f9mv0tb.27sf3j@ifi.uio.no>
2003-10-23 1:36 ` Michael Glasgow
2003-10-23 1:57 ` Andy Lutomirski
[not found] <fa.f36f4t9.1rg8j3v@ifi.uio.no>
2003-10-22 7:11 ` Michael Glasgow
2003-10-22 19:40 ` Andy Lutomirski
[not found] <fa.hehull9.10mmngt@ifi.uio.no>
2003-10-21 18:24 ` Andy Lutomirski
-- strict thread matches above, loose matches on Subject: below --
2003-10-21 11:26 Michael Glasgow
2003-10-23 16:46 ` Theodore Ts'o
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