src/lxc/tools/lxc_attach.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2010
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/ioctl.h>
  33 #include <sys/stat.h>
  34 #include <sys/types.h>
  35 #include <sys/wait.h>
  36 #include <termios.h>
  37 #include <unistd.h>
  38
  39 #include <lxc/lxccontainer.h>
  40
  41 #include "arguments.h"
  42 #include "attach.h"
  43 #include "caps.h"
  44 #include "config.h"
  45 #include "confile.h"
  46 #include "log.h"
  47 #include "utils.h"
  48
  49 lxc_log_define(lxc_attach, lxc);
  50
  51 static int my_parser(struct lxc_arguments *args, int c, char *arg);
  52 static int add_to_simple_array(char ***array, ssize_t *capacity, char *value);
  53 static bool stdfd_is_pty(void);
  54 static int lxc_attach_create_log_file(const char *log_file);
  55
  56 static int elevated_privileges;
  57 static signed long new_personality = -1;
  58 static int namespace_flags = -1;
  59 static int remount_sys_proc;
  60 static lxc_attach_env_policy_t env_policy = LXC_ATTACH_KEEP_ENV;
  61 static char **extra_env;
  62 static ssize_t extra_env_size;
  63 static char **extra_keep;
  64 static ssize_t extra_keep_size;
  65
  66 static const struct option my_longopts[] = {
  67         {"elevated-privileges", optional_argument, 0, 'e'},
  68         {"arch", required_argument, 0, 'a'},
  69         {"namespaces", required_argument, 0, 's'},
  70         {"remount-sys-proc", no_argument, 0, 'R'},
  71         /* TODO: decide upon short option names */
  72         {"clear-env", no_argument, 0, 500},
  73         {"keep-env", no_argument, 0, 501},
  74         {"keep-var", required_argument, 0, 502},
  75         {"set-var", required_argument, 0, 'v'},
  76         {"pty-log", required_argument, 0, 'L'},
  77         {"rcfile", required_argument, 0, 'f'},
  78         {"uid", required_argument, 0, 'u'},
  79         {"gid", required_argument, 0, 'g'},
  80         LXC_COMMON_OPTIONS
  81 };
  82
  83 static struct lxc_arguments my_args = {
  84         .progname     = "lxc-attach",
  85         .help         = "\
  86 --name=NAME [-- COMMAND]\n\
  87 \n\
  88 Execute the specified COMMAND - enter the container NAME\n\
  89 \n\
  90 Options :\n\
  91   -n, --name=NAME   NAME of the container\n\
  92   -e, --elevated-privileges=PRIVILEGES\n\
  93                     Use elevated privileges instead of those of the\n\
  94                     container. If you don't specify privileges to be\n\
  95                     elevated as OR'd list: CAP, CGROUP and LSM (capabilities,\n\
  96                     cgroup and restrictions, respectively) then all of them\n\
  97                     will be elevated.\n\
  98                     WARNING: This may leak privileges into the container.\n\
  99                     Use with care.\n\
 100   -a, --arch=ARCH   Use ARCH for program instead of container's own\n\
 101                     architecture.\n\
 102   -s, --namespaces=FLAGS\n\
 103                     Don't attach to all the namespaces of the container\n\
 104                     but just to the following OR'd list of flags:\n\
 105                     MOUNT, PID, UTSNAME, IPC, USER or NETWORK.\n\
 106                     WARNING: Using -s implies -e with all privileges\n\
 107                     elevated, it may therefore leak privileges into the\n\
 108                     container. Use with care.\n\
 109   -R, --remount-sys-proc\n\
 110                     Remount /sys and /proc if not attaching to the\n\
 111                     mount namespace when using -s in order to properly\n\
 112                     reflect the correct namespace context. See the\n\
 113                     lxc-attach(1) manual page for details.\n\
 114       --clear-env   Clear all environment variables before attaching.\n\
 115                     The attached shell/program will start with only\n\
 116                     container=lxc set.\n\
 117       --keep-env    Keep all current environment variables. This\n\
 118                     is the current default behaviour, but is likely to\n\
 119                     change in the future.\n\
 120   -L, --pty-log=FILE\n\
 121                     Log pty output to FILE\n\
 122   -v, --set-var     Set an additional variable that is seen by the\n\
 123                     attached program in the container. May be specified\n\
 124                     multiple times.\n\
 125       --keep-var    Keep an additional environment variable. Only\n\
 126                     applicable if --clear-env is specified. May be used\n\
 127                     multiple times.\n\
 128   -f, --rcfile=FILE\n\
 129                     Load configuration file FILE\n\
 130   -u, --uid=UID     Execute COMMAND with UID inside the container\n\
 131   -g, --gid=GID     Execute COMMAND with GID inside the container\n\
 132 ",
 133         .options      = my_longopts,
 134         .parser       = my_parser,
 135         .checker      = NULL,
 136         .log_priority = "ERROR",
 137         .log_file     = "none",
 138 };
 139
 140 static int my_parser(struct lxc_arguments *args, int c, char *arg)
 141 {
 142         int ret;
 143
 144         switch (c) {
 145         case 'e':
 146                 ret = lxc_fill_elevated_privileges(arg, &elevated_privileges);
 147                 if (ret)
 148                         return -1;
 149                 break;
 150         case 'R': remount_sys_proc = 1; break;
 151         case 'a':
 152                 new_personality = lxc_config_parse_arch(arg);
 153                 if (new_personality < 0) {
 154                         ERROR("Invalid architecture specified: %s", arg);
 155                         return -1;
 156                 }
 157                 break;
 158         case 's':
 159                 namespace_flags = 0;
 160
 161                 if (lxc_namespace_2_std_identifiers(arg) < 0)
 162                         return -1;
 163
 164                 ret = lxc_fill_namespace_flags(arg, &namespace_flags);
 165                 if (ret)
 166                         return -1;
 167
 168                 /* -s implies -e */
 169                 lxc_fill_elevated_privileges(NULL, &elevated_privileges);
 170                 break;
 171         case 500: /* clear-env */
 172                 env_policy = LXC_ATTACH_CLEAR_ENV;
 173                 break;
 174         case 501: /* keep-env */
 175                 env_policy = LXC_ATTACH_KEEP_ENV;
 176                 break;
 177         case 502: /* keep-var */
 178                 ret = add_to_simple_array(&extra_keep, &extra_keep_size, arg);
 179                 if (ret < 0) {
 180                         ERROR("Failed to alloc memory");
 181                         return -1;
 182                 }
 183                 break;
 184         case 'v':
 185                 ret = add_to_simple_array(&extra_env, &extra_env_size, arg);
 186                 if (ret < 0) {
 187                         ERROR("Failed to alloc memory");
 188                         return -1;
 189                 }
 190                 break;
 191         case 'L':
 192                 args->console_log = arg;
 193                 break;
 194         case 'f':
 195                 args->rcfile = arg;
 196                 break;
 197         case 'u':
 198                 if (lxc_safe_uint(arg, &args->uid) < 0)
 199                         return -1;
 200                 break;
 201         case 'g':
 202                 if (lxc_safe_uint(arg, &args->gid) < 0)
 203                         return -1;
 204                 break;
 205         }
 206
 207         return 0;
 208 }
 209
 210 static int add_to_simple_array(char ***array, ssize_t *capacity, char *value)
 211 {
 212         ssize_t count = 0;
 213
 214         if (!array)
 215                 return -1;
 216
 217         if (*array)
 218                 for (; (*array)[count]; count++);
 219
 220         /* we have to reallocate */
 221         if (count >= *capacity - 1) {
 222                 ssize_t new_capacity = ((count + 1) / 32 + 1) * 32;
 223
 224                 char **new_array = realloc((void*)*array, sizeof(char *) * new_capacity);
 225                 if (!new_array)
 226                         return -1;
 227
 228                 memset(&new_array[count], 0, sizeof(char*)*(new_capacity - count));
 229
 230                 *array = new_array;
 231                 *capacity = new_capacity;
 232         }
 233
 234         if (!(*array))
 235                 return -1;
 236
 237         (*array)[count] = value;
 238         return 0;
 239 }
 240
 241 static bool stdfd_is_pty(void)
 242 {
 243         if (isatty(STDIN_FILENO))
 244                 return true;
 245
 246         if (isatty(STDOUT_FILENO))
 247                 return true;
 248
 249         if (isatty(STDERR_FILENO))
 250                 return true;
 251
 252         return false;
 253 }
 254
 255 static int lxc_attach_create_log_file(const char *log_file)
 256 {
 257         int fd;
 258
 259         fd = open(log_file, O_CLOEXEC | O_RDWR | O_CREAT | O_APPEND, 0600);
 260         if (fd < 0) {
 261                 ERROR("Failed to open log file \"%s\"", log_file);
 262                 return -1;
 263         }
 264
 265         return fd;
 266 }
 267
 268 int main(int argc, char *argv[])
 269 {
 270         int ret = -1;
 271         int wexit = 0;
 272         struct lxc_log log;
 273         pid_t pid;
 274         lxc_attach_options_t attach_options = LXC_ATTACH_OPTIONS_DEFAULT;
 275         lxc_attach_command_t command = (lxc_attach_command_t){.program = NULL};
 276
 277         if (lxc_caps_init())
 278                 exit(EXIT_FAILURE);
 279
 280         if (lxc_arguments_parse(&my_args, argc, argv))
 281                 exit(EXIT_FAILURE);
 282
 283         log.name = my_args.name;
 284         log.file = my_args.log_file;
 285         log.level = my_args.log_priority;
 286         log.prefix = my_args.progname;
 287         log.quiet = my_args.quiet;
 288         log.lxcpath = my_args.lxcpath[0];
 289
 290         if (lxc_log_init(&log))
 291                 exit(EXIT_FAILURE);
 292
 293         if (geteuid())
 294                 if (access(my_args.lxcpath[0], O_RDONLY) < 0) {
 295                         ERROR("You lack access to %s", my_args.lxcpath[0]);
 296                         exit(EXIT_FAILURE);
 297                 }
 298
 299         struct lxc_container *c = lxc_container_new(my_args.name, my_args.lxcpath[0]);
 300         if (!c)
 301                 exit(EXIT_FAILURE);
 302
 303         if (my_args.rcfile) {
 304                 c->clear_config(c);
 305                 if (!c->load_config(c, my_args.rcfile)) {
 306                         ERROR("Failed to load rcfile");
 307                         lxc_container_put(c);
 308                         exit(EXIT_FAILURE);
 309                 }
 310
 311                 c->configfile = strdup(my_args.rcfile);
 312                 if (!c->configfile) {
 313                         ERROR("Out of memory setting new config filename");
 314                         lxc_container_put(c);
 315                         exit(EXIT_FAILURE);
 316                 }
 317         }
 318
 319         if (!c->may_control(c)) {
 320                 ERROR("Insufficent privileges to control %s", c->name);
 321                 lxc_container_put(c);
 322                 exit(EXIT_FAILURE);
 323         }
 324
 325         if (remount_sys_proc)
 326                 attach_options.attach_flags |= LXC_ATTACH_REMOUNT_PROC_SYS;
 327
 328         if (elevated_privileges)
 329                 attach_options.attach_flags &= ~(elevated_privileges);
 330
 331         if (stdfd_is_pty())
 332                 attach_options.attach_flags |= LXC_ATTACH_TERMINAL;
 333
 334         attach_options.namespaces = namespace_flags;
 335         attach_options.personality = new_personality;
 336         attach_options.env_policy = env_policy;
 337         attach_options.extra_env_vars = extra_env;
 338         attach_options.extra_keep_env = extra_keep;
 339
 340         if (my_args.argc > 0) {
 341                 command.program = my_args.argv[0];
 342                 command.argv = (char**)my_args.argv;
 343         }
 344
 345         if (my_args.console_log) {
 346                 attach_options.log_fd = lxc_attach_create_log_file(my_args.console_log);
 347                 if (attach_options.log_fd < 0)
 348                         goto out;
 349         }
 350
 351         if (my_args.uid)
 352                 attach_options.uid = my_args.uid;
 353
 354         if (my_args.gid)
 355                 attach_options.gid = my_args.gid;
 356
 357         if (command.program)
 358                 ret = c->attach(c, lxc_attach_run_command, &command, &attach_options, &pid);
 359         else
 360                 ret = c->attach(c, lxc_attach_run_shell, NULL, &attach_options, &pid);
 361         if (ret < 0)
 362                 goto out;
 363
 364         ret = lxc_wait_for_pid_status(pid);
 365         if (ret < 0)
 366                 goto out;
 367
 368         if (WIFEXITED(ret))
 369                 wexit = WEXITSTATUS(ret);
 370
 371 out:
 372         lxc_container_put(c);
 373         if (ret >= 0)
 374                 exit(wexit);
 375
 376         exit(EXIT_FAILURE);
 377 }