Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH v3] Restrict unprivileged access to kernel syslog | From | Dan Rosenberg <> | Date | Sun, 02 Jan 2011 11:08:55 -0500 |
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On Sun, 2011-01-02 at 10:05 +0100, Pavel Machek wrote: > Hi! > > > The kernel syslog contains debugging information that is often useful > > during exploitation of other vulnerabilities, such as kernel heap > > addresses. Rather than futilely attempt to sanitize hundreds (or > > thousands) of printk statements and simultaneously cripple useful > > debugging functionality, it is far simpler to create an option that > > prevents unprivileged users from reading the syslog. > > > > This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the > > dmesg_restrict sysctl. When set to "0", the default, no restrictions > > are enforced. When set to "1", only users with CAP_SYS_ADMIN can read > > the kernel syslog via dmesg(8) or other mechanisms. > > Ok, this is very very ugly. > > You essentially create a bit to control what other bit does. Clean > solution would be CAP_SYS_DMESG, and make sure that is given to > processes by default... > > ...and that would be actually very good thing -- on cellphones, you > want some users without ability to connect to network, so you could > introduce CAP_NETWORK etc... > > Pavel
The CONFIG was added on suggestion that it would make it easier for distributions to enable this behavior by default. The patch was modified to use CAP_SYSLOG, which seems in line with what you want.
Thanks, Dan
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