Re: [PATCH] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg

From: Josh Boyer
Date: Wed Feb 27 2013 - 13:13:29 EST

On Wed, Feb 27, 2013 at 10:05:47AM -0800, Kees Cook wrote:
> Hi,
> On Fri, Feb 22, 2013 at 01:18:57PM -0500, Josh Boyer wrote:
> > Originally, the addition of dmesg_restrict covered both the syslog
> > method of accessing dmesg, as well as /dev/kmsg itself. This was done
> > indirectly by security_syslog calling cap_syslog before doing any LSM
> > checks.
> Actually, are the security_syslog() checks in /dev/kmsg correct? There is
> only one used in devkmsg_open which uses SYSLOG_ACTION_READ_ALL. Shouldn't
> it be using SYSLOG_ACTION_OPEN? And have SYSLOG_ACTION_READ_ALL added to
> devkmsg_read? (And should we add one for write?)

You ask wonderful questions! I have no idea. Either way, it needs to
still somehow check for capable(CAP_SYSLOG) which security_syslog
doesn't do. So either what I have already, or your suggestion of using
the existing function with SYSLOG_ACTION_OPEN in devkmsg_open.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at