Syscalls cgroup subsystem for Linux
===================================

Syscalls is a cgroup subsystem that enables you to allow/deny specified system
calls for tasks in a given control group. It may be useful for hardening Linux
distributions by creating sandboxes of different kinds.

Installation
------------

To install this subsystem you have to apply supplied patch for a proper Linux source
tree. You do it typically for Linux patches:

$ ls
syscalls_cgroup.patch
$ wget http://www.kernel.org/pub/linux/kernel/v3.0/linux-3.1.5.tar.bz2
$ tar -xjf linux-3.1.5.tar.bz2
$ cd linux-3.1.5
$ patch -p1 -s < ../syscalls_cgroup.patch
$ make menuconfig
...
General setup -->
		  [*] Control Group support -->
		  		  [*] Syscalls controller for cgroups
...
$ make
...
Kernel: arch/x86/boot/bzImage is ready  (#1)
...

Usage
-----

You use this subsystem by mounting it into directory tree and echoing syscalls
numbers into syscalls.allow and syscalls.deny files to allow/deny certain
syscalls. For more info review Documentation/cgroups/cgroups.txt file in kernel
directory.

Example:

# mkdir /cgroup
# mount -t tmpfs cgroup_root /cgroup
# cd /cgroup
# mkdir syscalls
# mount -t cgroup -o syscalls syscalls_root syscalls
# ls
cgroup.clone_children	cgroup.procs			release_agent		syscalls.deny
cgroup.event_control	notify_on_release	syscalls.allow	tasks
# cat syscalls.allow
0 1 ... 311
# cat syscalls.deny

# cat tasks
1
2
...
# mkdir test1
# cd test1
# ls
cgroup.clone_children	cgroup.procs				syscalls.allow		tasks
cgroup.event_control	notify_on_release		syscalls.deny
# echo 0 > tasks
# cat tasks
2357
2374
# echo 83 > syscalls.deny # assume 83 is syscall number for 'mkdir'
# cat syscalls.deny
83
# mkdir test2
mkdir: cannot create directory 'test2': Function not implemented
# echo 83 > syscalls.allow
# mkdir test2
# cd ..
# echo 83 > syscalls.deny
# cd test1
# mkdir test3
mkdir: cannot create directory 'test3': Function not implemented
# echo 83 > syscalls.allow
-bash: echo: write error: Operation not permitted

Testing
-------

Subsystem comes with set of performance and system tests. For further info go to
'tests' directory.

Compatibility
-------------

Subsystem was tested with 3.1.x Linux kernels. Currently it supports only x86
and x86-64 architectures.

License
-------

See COPYING file.

Contact
-------

Lukasz Sowa
Mail: luksow@gmail.com