Date: Thu, 27 Oct 2011 16:04:53 -0600 From: Kurt Seifried <kseifried@...hat.com> To: oss-security@...ts.openwall.com, cve-assign@...re.org Subject: Re: CVE Request -- kernel: sysctl: restrict write access to dmesg_restrict Please revoke CVE-2011-4080 On 10/27/2011 01:35 PM, Petr Matousek wrote: > On Wed, Oct 26, 2011 at 07:53:10PM +0400, Vasiliy Kulikov wrote: >> Hi, >> >> On Wed, Oct 26, 2011 at 09:26 -0600, Kurt Seifried wrote: >>> On 10/26/2011 09:16 AM, Petr Matousek wrote: >>>> When dmesg_restrict is set to 1 CAP_SYS_ADMIN is needed to read the >>>> kernel ring buffer. But a root user without CAP_SYS_ADMIN is able >>>> to reset dmesg_restrict to 0. >>>> >>>> This is an issue when e.g. LXC (Linux Containers) are used and complete >>>> user space is running without CAP_SYS_ADMIN. A unprivileged and jailed >>>> root user can bypass the dmesg_restrict protection. >>>> >>>> Introduced by: >>>> eaf06b241b091357e72b76863ba16e89610d31bd >>>> >>>> Fixed by: >>>> bfdc0b497faa82a0ba2f9dddcf109231dd519fcc >>>> >>>> Thanks, >>> Please use CVE-2011-4080 for this issue. >> Why does it worth CVE? Procfs is not ready for containers yet. You can >> use other sysctls for more harmful things. E.g. kernel.core_pattern >> allows arbitrary code execution as a full root - does it need a CVE too >> then? :-) > Yes, you are right. I was aware of the procfs limitations, still it looked > to me that boundary explicitly defined in eaf06b2 is directly crossed in > this case. > > Anyway I agree that it is useless to issue CVE for each procfs flaw of > this kind. > > Kurt, could you please reject the CVE? > > Sorry for the noise, > Petr > >> root@...-ubuntu:/proc/sys/kernel# echo "|/usr/bin/touch /tmp/pwned" > core_pattern >> root@...-ubuntu:/proc/sys/kernel# cat >> ^\Quit (core dumped) >> >> (In the root namespace) >> $ ls /tmp/pwned >> /tmp/pwned >> >> -- >> Vasiliy Kulikov >> http://www.openwall.com - bringing security into open computing environments -- -Kurt Seifried / Red Hat Security Response Team
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