Re: [GIT PULL] kdbus for 4.1-rc1

Austin S Hemmelgarn
2015-04-21T19:55:27Z

[-- Attachment #1: Type: text/plain, Size: 1051 bytes --]

On 2015-04-21 15:38, Matthew Garrett wrote:
> On Tue, Apr 21, 2015 at 11:36:54AM -0500, Eric W. Biederman wrote:
>>
>> HeHeHe. You mean all I need to do to get around all of the logging servers is
>> capture CAP_SYS_BOOT? Say like just capture this crazy watchdog program
>> that doesn't run as root so that it can only reboot the system? HeHeHe
>> So I can just trigger a clean reboot wait for journald, auditd, and
>> syslog all to shut down and then do evil things to the machine without
>> having to worry about erasing forensic evidence?
>
> CAP_SYS_BOOT gives you kexec, and kexec with init=/bin/sh lets you do
> anything. You added that in dc009d92435f99498cbc579ce76bf28e837e2c14 and
> now the horse is long gone. Don't give CAP_SYS_BOOT to anything you
> don't trust with full privileges.
>
The point is that Eric's suggestion works even on kernels without
kexec(), which is significant because a significant number of security
minded people (myself included) explicitly disable kexec in their kernel
configuration.

[-- Attachment #2: S/MIME Cryptographic Signature --]
[-- Type: application/pkcs7-signature, Size: 2967 bytes --]