lxcsu-internal

   1 #!/usr/bin/python
   2
   3
   4 import setns
   5 import os
   6 import sys
   7
   8 from argparse import ArgumentParser
   9
  10 drop_capabilities='cap_sys_admin,cap_sys_boot,cap_sys_module'
  11
  12 debug = False
  13
  14 def getarch(f):
  15     output = os.popen('readelf -h %s 2>&1'%f).readlines()
  16     classlines = [x for x in output if ('Class' in x.split(':')[0])]
  17     line = classlines[0]
  18     c = line.split(':')[1]
  19     if ('ELF64' in c):
  20         return 'x86_64'
  21     elif ('ELF32' in c):
  22         return 'i686'
  23     else:
  24         raise Exception('Could not determine architecture')
  25
  26 def umount(fs_dir):
  27     output = os.popen('/bin/umount %s 2>&1'%fs_dir).read()
  28     return ('device is busy' not in output)
  29
  30 def main ():
  31     parser = ArgumentParser()
  32     parser.add_argument("-n", "--nonet",
  33                         action="store_true", dest="netns", default=False,
  34                         help="Don't enter network namespace")
  35     parser.add_argument("-m", "--nomnt",
  36                         action="store_true", dest="mntns", default=False,
  37                         help="Don't enter mount namespace")
  38     parser.add_argument("-p", "--nopid",
  39                         action="store_true", dest="pidns", default=False,
  40                         help="Don't enter pid namespace")
  41     parser.add_argument("-r", "--root",
  42                         action="store_true", dest="root", default=False,
  43                         help="Enter as root: be careful")
  44     parser.add_argument("-d","--debug",
  45                         action='store_true', dest='debug', default=False,
  46                         help="debug option")
  47     parser.add_argument ("slice_name")
  48     parser.add_argument ("command_to_run",nargs="*")
  49
  50     args = parser.parse_args()
  51     slice_name=args.slice_name
  52     # support for either setting debug at the top of this file, or on the command-line
  53     if args.debug:
  54         global debug
  55         debug=True
  56
  57     try:
  58         cmd = 'grep %s /proc/*/cgroup | grep freezer'%slice_name
  59         output = os.popen(cmd).readlines()
  60 #        if debug: print "output of grep freezer has %s lines"%len(output)
  61     except:
  62         print "Error finding slice %s"%slice_name
  63         exit(1)
  64
  65     slice_spec = None
  66
  67     # provide a default as this is not always properly computed
  68     arch = None
  69
  70     for e in output:
  71         try:
  72             l = e.rstrip()
  73             path = l.split(':')[0]
  74             comp = l.rsplit(':')[-1]
  75             slice_name_check = comp.rsplit('/')[-1]
  76             if debug: print "dealing with >%s<"%slice_name_check
  77
  78             if (slice_name_check == slice_name):
  79                 if debug: print "found %s"%slice_name
  80                 slice_path = path
  81                 pid = slice_path.split('/')[2]
  82                 cmdline = open('/proc/%s/cmdline'%pid).read().rstrip('\n\x00')
  83                 if (cmdline == '/sbin/init') or (cmdline.startswith("init [")):
  84                     slice_spec = slice_path
  85                     arch = getarch('/proc/%s/exe'%pid)
  86                     break
  87         except Exception,e:
  88             if debug:
  89                 import traceback
  90                 print "BEG lxcsu - ignoring exception"
  91                 traceback.print_exc()
  92                 print "END lxcsu - ignoring exception"
  93             pass
  94
  95     if (not slice_spec or not pid):
  96         print "Not started: %s"%slice_name
  97         exit(1)
  98
  99     if arch is None:
 100         arch = 'x86_64'
 101
 102     # Set sysctls specific to slice
 103     sysctl_dir = '/etc/planetlab/vsys-attributes/%s'%slice_name
 104     if (os.access(sysctl_dir,0)):
 105         entries = os.listdir(sysctl_dir)
 106         for e in entries:
 107             prefix = 'vsys_sysctl.'
 108             if (e.startswith(prefix)):
 109                 sysctl_file = '/'.join([sysctl_dir,e])
 110                 sysctl_name = e[len(prefix):]
 111                 sysctl_val = open(sysctl_file).read()
 112                 os.system('sysctl -w %s=%s'%(sysctl_name,sysctl_val))
 113
 114     # Enter cgroups
 115     try:
 116         for subsystem in ['cpuset','memory','blkio']:
 117             open('/sys/fs/cgroup/%s/libvirt/lxc/%s/tasks'%(subsystem,slice_name),'w').write(str(os.getpid()))
 118
 119     except:
 120         print "Error assigning resources: %s"%slice_name
 121         exit(1)
 122
 123     try:
 124         open('/sys/fs/cgroup/cpuacct/system/libvirtd.service/libvirt/lxc/%s/tasks'%slice_name,'w').write(str(os.getpid()))
 125     except:
 126         print "Error assigning cpuacct: %s" % slice_name
 127         exit(1)
 128
 129     # If the slice is frozen, then we'll get an EBUSY when trying to write to the task
 130     # list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
 131     # in this case to error out the shell. (an alternative would be to un-freeze it,
 132     # add the task, and re-freeze it)
 133     try:
 134         f=open('/sys/fs/cgroup/freezer/libvirt/lxc/%s/tasks'%(slice_name),'w')
 135         f.write(str(os.getpid()))
 136         # note: we need to call f.close() explicitly, or we'll get an exception in
 137         # the object destructor, which will not be caught
 138         f.close()
 139     except:
 140         print "Error adding task to freezer cgroup. Slice is probably frozen: %s" % slice_name
 141         exit(1)
 142
 143     setns.chcontext('/proc/%s/ns/uts'%pid)
 144     setns.chcontext('/proc/%s/ns/ipc'%pid)
 145
 146     if (not args.pidns):
 147         setns.chcontext('/proc/%s/ns/pid'%pid)
 148
 149     if (not args.netns):
 150         setns.chcontext('/proc/%s/ns/net'%pid)
 151
 152     if (not args.mntns):
 153         setns.chcontext('/proc/%s/ns/mnt'%pid)
 154
 155
 156
 157     proc_mounted = False
 158     if (not os.access('/proc/self',0)):
 159         proc_mounted = True
 160         setns.proc_mount()
 161
 162
 163
 164     # cgroups is not yet LXC-safe, so we need to use the course grained access control
 165     # strategy of unmounting the filesystem
 166
 167     umount_result = True
 168     for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event']:
 169         fs_path = '/sys/fs/cgroup/%s'%subsystem
 170         if (not umount(fs_path)):
 171             print "Error disabling cgroup access"
 172             exit(1)
 173
 174     if (not umount('/sys/fs/cgroup')):
 175         print "Error disabling cgroup access"
 176         exit(1)
 177
 178     pid = os.fork()
 179
 180     if (pid == 0):
 181         cap_arg = '--drop='+drop_capabilities
 182
 183         if (not args.root):
 184             exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--user=%s'%slice_name,'--','--login',]+args.command_to_run
 185         else:
 186             exec_args = [arch,'/usr/sbin/capsh','--','--login']+args.command_to_run
 187
 188         os.environ['SHELL'] = '/bin/sh'
 189 # Thierry's suggestion:os.environ['HOME'] = '/home/%s'%slice_name
 190         if debug: print 'lxcsu-internal:execv:','/usr/bin/setarch',exec_args
 191         os.execv('/usr/bin/setarch',exec_args)
 192     else:
 193         setns.proc_umount()
 194         _,status = os.waitpid(pid,0)
 195         exit(os.WEXITSTATUS(status))
 196
 197 if __name__ == '__main__':
 198     main()