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From: Ernie Petrides <petrides@redhat.com>
To: "Michael Glasgow" <glasgowNOSPAM@beer.net>
Cc: "Theodore Ts'o" <tytso@mit.edu>, linux-kernel@vger.kernel.org
Subject: Re: posix capabilities inheritance
Date: Thu, 23 Oct 2003 21:36:36 -0400	[thread overview]
Message-ID: <200310240136.h9O1aaOU002931@pasta.boston.redhat.com> (raw)
In-Reply-To: Your message of "Thu, 23 Oct 2003 17:05:40 CDT." <200310232205.h9NM5eOc004400@dark.beer.net>

On Thursday, 23-Oct-2003 at 17:5 CDT, "Michael Glasgow" wrote:

> 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.

Cheers.  -ernie

  parent reply	other threads:[~2003-10-24  1:36 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 [this message]
2003-10-24  2:19     ` Bernd Eckenfels
2003-10-24  5:10       ` Ernie Petrides
2003-10-25 19:51     ` Pavel Machek
     [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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