Prevent slices from accessing cgroups fs

[lxc-userspace.git] / lxcsu

diff --git a/lxcsu b/lxcsu
index a72239e..abc98be 100644 (file)
--- a/lxcsu
+++ b/lxcsu
@@ -9,6 +9,11 @@ import sys
 
 drop_capabilities='cap_sys_admin,cap_sys_boot,cap_sys_module'.split(',')
 
+def umount(fs_dir):
+    output = os.popen('/bin/umount %s 2>&1'%fs_dir).read()
+    return ('device is busy' not in fs_dir)
+
+
 """
 parser = OptionParser()
 parser.add_option("-n", "--net",
@@ -69,6 +74,12 @@ except:
     print "Error assigning resources: %s"%slice_name
     exit(1)
 
+try:
+    open('/sys/fs/cgroup/cpuacct/system/libvirtd.service/libvirt/lxc/%s/tasks'%slice_name,'w').write(str(os.getpid()))
+except:
+    print "Error assigning cpuacct: %s" % slice_name
+    exit(1)
+
 # If the slice is frozen, then we'll get an EBUSY when trying to write to the task
 # list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
 # in this case to error out the shell. (an alternative would be to un-freeze it,
@@ -84,18 +95,32 @@ except:
     exit(1)
 
 r1 = setns.chcontext('/proc/%s/ns/uts'%pid)
-
 r2 = setns.chcontext('/proc/%s/ns/ipc'%pid)
 r3 = setns.chcontext('/proc/%s/ns/net'%pid)
 
 open('/proc/lxcsu','w').write(pid)
 open('/proc/pidsu','w').write(pid)
 
+# cgroups is not yet LXC-safe, so we need to use the course grained access control
+# strategy of unmounting the filesystem
+
+umount_result = True
+for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event']:
+    fs_path = '/sys/fs/cgroup/%s'%subsystem
+    if (not umount(fs_path)):
+        print "Error disabling cgroup access"
+        exit(1)
+
+if (not umount('/sys/fs/cgroup')):
+    print "Error disabling cgroup access"
+    exit(1)
+
 pid = os.fork()
 
 cap_args = map(lambda c:'--drop='+c, drop_capabilities)
     
 if (pid == 0):
+    os.environ['SHELL'] = '/bin/sh'
     os.execv('/usr/sbin/capsh',cap_args+['--','--login']+args[1:])
 else:
     os.waitpid(pid,0)