#!/usr/bin/python3 import sys import os import setns import pwd from argparse import ArgumentParser # can set to True here, but also use the -d option debug = False def getarch(pid): exe_filename = '/proc/%s/exe' % pid output = os.popen('readelf -h %s 2>&1' % exe_filename).readlines() classlines = [x for x in output if ('Class' in x.split(':')[0])] line = classlines[0] c = line.split(':')[1] if ('ELF64' in c): return 'x86_64' elif ('ELF32' in c): return 'i686' else: raise Exception('Could not determine architecture for pid %s' % pid) def get_cgroup_subdirs_for_pid(pid): cgroup_info_file = '/proc/%s/cgroup' % pid cgroup_lines = open(cgroup_info_file).read().splitlines() subdirs = {} for line in cgroup_lines: try: _, cgroup_name, subdir = line.split(':') subdirs[cgroup_name] = subdir except Exception as e: print("Error reading cgroup info: %s" % str(e)) pass return subdirs def umount(fs_dir, opts=''): output = os.popen('/bin/umount %s %s 2>&1' % (opts, fs_dir)).read() return ('device is busy' not in output) def main(): parser = ArgumentParser() parser.add_argument("-n", "--nonet", action="store_true", dest="no_netns", default=False, help="Don't enter network namespace") parser.add_argument("-m", "--nomnt", action="store_true", dest="no_mntns", default=False, help="Don't enter mount namespace") parser.add_argument("-p", "--nopid", action="store_true", dest="no_pidns", default=False, help="Don't enter pid namespace") parser.add_argument("-r", "--root", action="store_true", dest="root", default=False, help="Enter as root: be careful") parser.add_argument("-i", "--internal", action="store_true", dest="internal", default=False, help="does *not* prepend '-- -c' to arguments - or invoke lxcsu-internal") parser.add_argument("-d", "--debug", action='store_true', dest='debug', default=False, help="debug option") parser.add_argument("-s", "--nosliceuid", action='store_true', dest="nosliceuid", default=False, help="do not change to slice uid inside of slice") parser.add_argument("-o", "--noslicehome", action='store_true', dest="noslicehome", default=False, help="do not change to slice home directory inside of slice") if os.path.exists("/etc/lxcsu_default"): defaults = parser.parse_args( file("/etc/lxcsu_default", "r").read().split()) parser.set_defaults(**defaults.__dict__) parser.add_argument("slice_name") parser.add_argument("command_to_run", nargs="*") args = parser.parse_args() slice_name = args.slice_name # support for either setting debug at the top of this file, or on the command-line if args.debug: global debug debug = True # somehow some older nodes won't be able to find the login name in /etc/passwd # when this is done down the road, so compute slice_uid while in a safe env # even though we don't use the slice_uid any more, this is still # checked later on as a means to ensure existence of the slice account try: slice_uid = pwd.getpwnam(slice_name).pw_uid except Exception as e: if debug: import traceback print('error while computing slice_uid', e) traceback.print_exc() slice_uid = None # unless we run the symlink 'lxcsu-internal', or we specify the -i option, prepend '--' '-c' if sys.argv[0].find('internal') >= 0: args.internal = True if len(args.command_to_run) > 0 and (args.command_to_run[0] == "/sbin/service"): # A quick hack to support nodemanager interfaces.py when restarting # networking in a slice. args.nosliceuid = True # plain lxcsu if not args.internal: # no command given: enter interactive shell if not args.command_to_run: args.command_to_run = ['/bin/sh'] args.command_to_run = ['-c'] + [" ".join(args.command_to_run)] try: cmd = '/usr/bin/virsh --connect lxc:/// domid %s' % slice_name # convert to int as a minimal raincheck driver_pid = int(os.popen(cmd).read().strip()) # locate the pid for the - expected - single child, that would be the init for that VM #init_pid = int(open("/proc/%s/task/%s/children"%(driver_pid,driver_pid)).read().strip()) init_pid = int(os.popen('pgrep -P %s' % driver_pid).readlines()[0].strip()) # Thierry: I am changing the code below to use init_pid instead of driver_pid # for the namespace handling features, that I was able to check # I've left the other ones as they were, i.e. using driver_pid, but I suspect # some should be changed as well except: print("Domain %s not found" % slice_name) exit(1) if not driver_pid or not init_pid: print("Domain %s not started" % slice_name) exit(1) if debug: print("Found driver_pid", driver_pid, 'and init_pid=', init_pid) # driver_pid is always x86_64, we need to look at the VM's init process here arch = getarch(init_pid) # Set sysctls specific to slice sysctls = [] sysctl_dir = '/etc/planetlab/vsys-attributes/%s' % slice_name if (os.access(sysctl_dir, 0)): entries = os.listdir(sysctl_dir) for e in entries: prefix = 'vsys_sysctl.' if (e.startswith(prefix)): sysctl_file = '/'.join([sysctl_dir, e]) sysctl_name = e[len(prefix):] sysctl_val = open(sysctl_file).read() sysctls.append((sysctl_file, sysctl_name, sysctl_val)) # xxx probably init_pid here too subdirs = get_cgroup_subdirs_for_pid(driver_pid) sysfs_root = '/sys/fs/cgroup' # 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, # add the task, and re-freeze it) # Enter cgroups current_cgroup = '' for subsystem in ['cpuset', 'memory', 'blkio', 'cpuacct', 'cpuacct,cpu', 'freezer']: try: current_cgroup = subsystem # There seems to be a bug in the cgroup schema: cpuacct,cpu can become cpu,cpuacct # We need to handle both task_path_alt = None try: subsystem_comps = subsystem.split(',') subsystem_comps.reverse() subsystem_alt = ','.join(subsystem_comps) tasks_path_alt = [sysfs_root, subsystem_alt, subdirs[subsystem], 'tasks'] except Exception as e: pass tasks_path = [sysfs_root, subsystem, subdirs[subsystem], 'tasks'] tasks_path_str = '/'.join(tasks_path) try: f = open(tasks_path_str, 'w') except: tasks_path_alt_str = '/'.join(tasks_path_alt) f = open(tasks_path_alt_str, 'w') f.write(str(os.getpid())) if (subsystem == 'freezer'): f.close() except Exception as e: if (subsystem not in subdirs): pass else: if debug: print(e) print("Error assigning cgroup %s (pid=%s) for slice %s" % (current_cgroup, driver_pid, slice_name)) exit(1) def chcontext(path): retcod = setns.chcontext(path) if retcod != 0: print('WARNING - setns(%s)=>%s (ignored)' % (path, retcod)) return retcod # Use init_pid and not driver_pid to locate reference namespaces ref_ns = "/proc/%s/ns/" % init_pid if True: chcontext(ref_ns+'uts') if True: chcontext(ref_ns+'ipc') if (not args.no_pidns): chcontext(ref_ns+'pid') if (not args.no_netns): chcontext(ref_ns+'net') if (not args.no_mntns): chcontext(ref_ns+'mnt') proc_mounted = False if (not os.access('/proc/self', 0)): proc_mounted = True setns.proc_mount() for (sysctl_file, sysctl_name, sysctl_val) in sysctls: for fn in ["/sbin/sysctl", "/usr/sbin/sysctl", "/bin/sysctl", "/usr/bin/sysctl"]: if os.path.exists(fn): os.system('%s -w %s=%s >/dev/null 2>&1' % (fn, sysctl_name, sysctl_val)) break else: print("Error: image does not have a sysctl binary") # cgroups is not yet LXC-safe, so we need to use the coarse 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', 'systemd']: fs_path = '/sys/fs/cgroup/%s' % subsystem if (not umount(fs_path, '-l')): print('WARNING - umount failed (ignored) with path=', fs_path) pass # Leaving these comments for historical reference # print "Error disabling cgroup access" # exit(1) - Don't need this because failure here implies failure in the call to umount /sys/fs/cgroup if (not umount('/sys/fs/cgroup')): print("Error disabling cgroup access") exit(1) fork_pid = os.fork() if (fork_pid == 0): if (not args.root): setns.drop_caps() if (args.nosliceuid): # we still want to drop capabilities, but don't want to switch UIDs exec_args = [arch, '/bin/sh', '--login', ]+args.command_to_run else: if not slice_uid: print("lxcsu could not spot %s in /etc/passwd - exiting" % slice_name) exit(1) exec_args = [arch, '/usr/bin/sudo', '-u', slice_name, '/bin/sh', '--login', ]+args.command_to_run # once we can drop f12, it would be nicer to instead go for # exec_args = [arch,'/usr/sbin/capsh',cap_arg,'--user=%s'%slice_name,'--login',]+args.command_to_run else: exec_args = [arch, '/bin/sh', '--login']+args.command_to_run os.environ['SHELL'] = '/bin/sh' if os.path.exists('/etc/planetlab/lib/bind_public.so'): os.environ['LD_PRELOAD'] = '/etc/planetlab/lib/bind_public.so' if not args.noslicehome: os.environ['HOME'] = '/home/%s' % slice_name os.chdir("/home/%s" % (slice_name)) if debug: print('lxcsu:execv:', '/usr/bin/setarch', exec_args) os.execv('/usr/bin/setarch', exec_args) else: setns.proc_umount() _, status = os.waitpid(fork_pid, 0) exit(os.WEXITSTATUS(status)) if __name__ == '__main__': main()