7 from argparse import ArgumentParser
9 drop_capabilities='cap_sys_admin,cap_sys_boot,cap_sys_module'
11 # can set to True here, but also use the -d option
15 output = os.popen('readelf -h %s 2>&1'%f).readlines()
16 classlines = [x for x in output if ('Class' in x.split(':')[0])]
18 c = line.split(':')[1]
24 raise Exception('Could not determine architecture')
27 output = os.popen('/bin/umount %s 2>&1'%fs_dir).read()
28 return ('device is busy' not in output)
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("-i","--internal",
45 action="store_true", dest="internal", default=False,
46 help="does *not* prepend '-- -c' to arguments - or invoke lxcsu-internal")
47 parser.add_argument("-d","--debug",
48 action='store_true', dest='debug', default=False,
50 parser.add_argument ("slice_name")
51 parser.add_argument ("command_to_run",nargs="*")
53 args = parser.parse_args()
54 slice_name=args.slice_name
56 # unless we run the symlink 'lxcsu-internal', or we specify the -i option, prepend '--' '-c'
57 if sys.argv[0].find('internal')>=0: args.internal=True
61 # no command given: enter interactive shell
62 if not args.command_to_run: args.command_to_run=['/bin/sh']
63 args.command_to_run = [ '-c' ] + args.command_to_run
65 # support for either setting debug at the top of this file, or on the command-line
71 cmd = 'grep %s /proc/*/cgroup | grep freezer'%slice_name
72 output = os.popen(cmd).readlines()
74 print "Error finding slice %s"%slice_name
79 # provide a default as this is not always properly computed
85 path = l.split(':')[0]
86 comp = l.rsplit(':')[-1]
87 slice_name_check = comp.rsplit('/')[-1]
88 if debug: print "dealing with >%s<"%slice_name_check
90 if (slice_name_check == slice_name):
91 if debug: print "found %s"%slice_name
93 pid = slice_path.split('/')[2]
94 cmdline = open('/proc/%s/cmdline'%pid).read().rstrip('\n\x00')
95 if (cmdline == '/sbin/init') or (cmdline.startswith("init [")):
96 slice_spec = slice_path
97 arch = getarch('/proc/%s/exe'%pid)
102 print "BEG lxcsu - ignoring exception"
103 traceback.print_exc()
104 print "END lxcsu - ignoring exception"
107 if (not slice_spec or not pid):
108 print "Not started: %s"%slice_name
114 # Set sysctls specific to slice
116 sysctl_dir = '/etc/planetlab/vsys-attributes/%s'%slice_name
117 if (os.access(sysctl_dir,0)):
118 entries = os.listdir(sysctl_dir)
120 prefix = 'vsys_sysctl.'
121 if (e.startswith(prefix)):
122 sysctl_file = '/'.join([sysctl_dir,e])
123 sysctl_name = e[len(prefix):]
124 sysctl_val = open(sysctl_file).read()
125 sysctls.append((sysctl_file, sysctl_name, sysctl_val))
129 for subsystem in ['cpuset','memory','blkio']:
130 open('/sys/fs/cgroup/%s/libvirt/lxc/%s/tasks'%(subsystem,slice_name),'w').write(str(os.getpid()))
133 print "Error assigning resources: %s"%slice_name
137 open('/sys/fs/cgroup/cpuacct/system/libvirtd.service/libvirt/lxc/%s/tasks'%slice_name,'w').write(str(os.getpid()))
139 print "Error assigning cpuacct: %s" % slice_name
142 # If the slice is frozen, then we'll get an EBUSY when trying to write to the task
143 # list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
144 # in this case to error out the shell. (an alternative would be to un-freeze it,
145 # add the task, and re-freeze it)
147 f=open('/sys/fs/cgroup/freezer/libvirt/lxc/%s/tasks'%(slice_name),'w')
148 f.write(str(os.getpid()))
149 # note: we need to call f.close() explicitly, or we'll get an exception in
150 # the object destructor, which will not be caught
153 print "Error adding task to freezer cgroup. Slice is probably frozen: %s" % slice_name
156 setns.chcontext('/proc/%s/ns/uts'%pid)
157 setns.chcontext('/proc/%s/ns/ipc'%pid)
160 setns.chcontext('/proc/%s/ns/pid'%pid)
163 setns.chcontext('/proc/%s/ns/net'%pid)
166 setns.chcontext('/proc/%s/ns/mnt'%pid)
169 if (not os.access('/proc/self',0)):
173 for (sysctl_file, sysctl_name, sysctl_val) in sysctls:
174 for fn in ["/sbin/sysctl", "/usr/sbin/sysctl", "/bin/sysctl", "/usr/bin/sysctl"]:
175 if os.path.exists(fn):
176 os.system("mount -o remount,rw none /proc/sys")
177 os.system('%s -w %s=%s'%(fn, sysctl_name,sysctl_val))
178 os.system("mount -o remount,ro none /proc/sys")
181 print "Error: image does not have a sysctl binary"
183 # cgroups is not yet LXC-safe, so we need to use the coarse grained access control
184 # strategy of unmounting the filesystem
187 for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event']:
188 fs_path = '/sys/fs/cgroup/%s'%subsystem
189 if (not umount(fs_path)):
190 print "Error disabling cgroup access"
193 if (not umount('/sys/fs/cgroup')):
194 print "Error disabling cgroup access"
199 # capsh has a --user option starting with f14
200 # so if only for f12 we need to fake this one
202 # capsh.c does essentially the following when invoked with --user:
203 # pwd = getpwnam(user); ...
204 # ngroups = MAX_GROUPS;
205 # status = getgrouplist(user, pwd->pw_gid, groups, &ngroups); ...
206 # status = setgroups(ngroups, groups); ...
207 # status = setgid(pwd->pw_gid); ...
208 # status = setuid(pwd->pw_uid); ...
209 # however we cannot simulate that ourselves because if we did in this process then
210 # capsh could not be allowed to mess with caps any more
212 def getuid (slicename):
215 return pwd.getpwnam(slicename).pw_uid
220 cap_arg = '--drop='+drop_capabilities
223 uid = getuid (slice_name)
225 print "lxcsu could not spot %s in /etc/passwd - exiting"%slice_name
227 exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--uid=%s'%uid,'--','--login',]+args.command_to_run
228 # once we can drop f12, it would be nicer to instead go for
229 # exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--user=%s'%slice_name,'--','--login',]+args.command_to_run
231 exec_args = [arch,'/usr/sbin/capsh','--','--login']+args.command_to_run
233 os.environ['SHELL'] = '/bin/sh'
234 os.environ['HOME'] = '/home/%s'%slice_name
235 os.environ['LD_PRELOAD'] = '/etc/planetlab/lib/bind_public.so'
236 os.chdir("/home/%s"%(slice_name))
237 if debug: print 'lxcsu:execv:','/usr/bin/setarch',exec_args
238 os.execv('/usr/bin/setarch',exec_args)
241 _,status = os.waitpid(pid,0)
242 exit(os.WEXITSTATUS(status))
244 if __name__ == '__main__':