lxc_start.c

/*
 * lxc: linux Container library
 *
 * (C) Copyright IBM Corp. 2007, 2008
 *
 * Authors:
 * Daniel Lezcano <daniel.lezcano at free.fr>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include "config.h"

#include <stdio.h>
#include <libgen.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/param.h>
#include <sys/utsname.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <net/if.h>

#include <lxc/lxccontainer.h>

#include "log.h"
#include "caps.h"
#include "lxc.h"
#include "conf.h"
#include "cgroup.h"
#include "utils.h"
#include "confile.h"
#include "arguments.h"

#define OPT_SHARE_NET OPT_USAGE + 1
#define OPT_SHARE_IPC OPT_USAGE + 2
#define OPT_SHARE_UTS OPT_USAGE + 3

lxc_log_define(lxc_start_ui, lxc);

static struct lxc_list defines;

static int ensure_path(char **confpath, const char *path)
{
	int err = -1, fd;
	char *fullpath = NULL;

	if (path) {
		if (access(path, W_OK)) {
			fd = creat(path, 0600);
			if (fd < 0 && errno != EEXIST) {
				SYSERROR("failed to create '%s'", path);
				goto err;
			}
			if (fd >= 0)
				close(fd);
		}

		fullpath = realpath(path, NULL);
		if (!fullpath) {
			SYSERROR("failed to get the real path of '%s'", path);
			goto err;
		}

		*confpath = fullpath;
	}
	err = EXIT_SUCCESS;

err:
	return err;
}

static int pid_from_lxcname(const char *lxcname_or_pid, const char *lxcpath) {
	char *eptr;
	int pid = strtol(lxcname_or_pid, &eptr, 10);
	if (*eptr != '\0' || pid < 1) {
		struct lxc_container *s;
		s = lxc_container_new(lxcname_or_pid, lxcpath);
		if (!s) {
			SYSERROR("'%s' is not a valid pid nor a container name", lxcname_or_pid);
			return -1;
		}

		if (!s->may_control(s)) {
			SYSERROR("Insufficient privileges to control container '%s'", s->name);
			lxc_container_put(s);
			return -1;
		}

		pid = s->init_pid(s);
		if (pid < 1) {
			SYSERROR("Is container '%s' running?", s->name);
			lxc_container_put(s);
			return -1;
		}

		lxc_container_put(s);
	}
	if (kill(pid, 0) < 0) {
		SYSERROR("Can't send signal to pid %d", pid);
		return -1;
	}

	return pid;
}

static int open_ns(int pid, const char *ns_proc_name) {
	int fd;
	char path[MAXPATHLEN];
	snprintf(path, MAXPATHLEN, "/proc/%d/ns/%s", pid, ns_proc_name);

	fd = open(path, O_RDONLY);
	if (fd < 0) {
		SYSERROR("failed to open %s", path);
		return -1;
	}
	return fd;
}

static int my_parser(struct lxc_arguments* args, int c, char* arg)
{
	switch (c) {
	case 'c': args->console = arg; break;
	case 'L': args->console_log = arg; break;
	case 'd': args->daemonize = 1; break;
	case 'F': args->daemonize = 0; break;
	case 'f': args->rcfile = arg; break;
	case 'C': args->close_all_fds = 1; break;
	case 's': return lxc_config_define_add(&defines, arg);
	case 'p': args->pidfile = arg; break;
	case OPT_SHARE_NET: args->share_ns[LXC_NS_NET] = arg; break;
	case OPT_SHARE_IPC: args->share_ns[LXC_NS_IPC] = arg; break;
	case OPT_SHARE_UTS: args->share_ns[LXC_NS_UTS] = arg; break;
	}
	return 0;
}

static const struct option my_longopts[] = {
	{"daemon", no_argument, 0, 'd'},
	{"foreground", no_argument, 0, 'F'},
	{"rcfile", required_argument, 0, 'f'},
	{"define", required_argument, 0, 's'},
	{"console", required_argument, 0, 'c'},
	{"console-log", required_argument, 0, 'L'},
	{"close-all-fds", no_argument, 0, 'C'},
	{"pidfile", required_argument, 0, 'p'},
	{"share-net", required_argument, 0, OPT_SHARE_NET},
	{"share-ipc", required_argument, 0, OPT_SHARE_IPC},
	{"share-uts", required_argument, 0, OPT_SHARE_UTS},
	LXC_COMMON_OPTIONS
};

static struct lxc_arguments my_args = {
	.progname = "lxc-start",
	.help     = "\
--name=NAME -- COMMAND\n\
\n\
lxc-start start COMMAND in specified container NAME\n\
\n\
Options :\n\
  -n, --name=NAME        NAME of the container\n\
  -d, --daemon           Daemonize the container (default)\n\
  -F, --foreground       Start with the current tty attached to /dev/console\n\
  -p, --pidfile=FILE     Create a file with the process id\n\
  -f, --rcfile=FILE      Load configuration file FILE\n\
  -c, --console=FILE     Use specified FILE for the container console\n\
  -L, --console-log=FILE Log container console output to FILE\n\
  -C, --close-all-fds    If any fds are inherited, close them\n\
                         If not specified, exit with failure instead\n\
                         Note: --daemon implies --close-all-fds\n\
  -s, --define KEY=VAL   Assign VAL to configuration variable KEY\n\
      --share-[net|ipc|uts]=NAME Share a namespace with another container or pid\n\
",
	.options   = my_longopts,
	.parser    = my_parser,
	.checker   = NULL,
	.daemonize = 1,
	.pidfile = NULL,
};

int main(int argc, char *argv[])
{
	int err = EXIT_FAILURE;
	struct lxc_conf *conf;
	struct lxc_log log;
	char *const *args;
	char *rcfile = NULL;
	char *const default_args[] = {
		"/sbin/init",
		NULL,
	};
	struct lxc_container *c;

	lxc_list_init(&defines);

	if (lxc_caps_init())
		exit(err);

	if (lxc_arguments_parse(&my_args, argc, argv))
		exit(err);

	if (!my_args.argc)
		args = default_args;
	else
		args = my_args.argv;

	log.name = my_args.name;
	log.file = my_args.log_file;
	log.level = my_args.log_priority;
	log.prefix = my_args.progname;
	log.quiet = my_args.quiet;
	log.lxcpath = my_args.lxcpath[0];

	if (lxc_log_init(&log))
		exit(err);
	lxc_log_options_no_override();

	if (access(my_args.lxcpath[0], O_RDONLY) < 0) {
		if (!my_args.quiet)
			fprintf(stderr, "You lack access to %s\n", my_args.lxcpath[0]);
		exit(err);
	}

	const char *lxcpath = my_args.lxcpath[0];

	/*
	 * rcfile possibilities:
	 * 1. rcfile from random path specified in cli option
	 * 2. rcfile not specified, use $lxcpath/$lxcname/config
	 * 3. rcfile not specified and does not exist.
	 */
	/* rcfile is specified in the cli option */
	if (my_args.rcfile) {
		rcfile = (char *)my_args.rcfile;
		c = lxc_container_new(my_args.name, lxcpath);
		if (!c) {
			ERROR("Failed to create lxc_container");
			exit(err);
		}
		c->clear_config(c);
		if (!c->load_config(c, rcfile)) {
			ERROR("Failed to load rcfile");
			lxc_container_put(c);
			exit(err);
		}
		c->configfile = strdup(my_args.rcfile);
		if (!c->configfile) {
			ERROR("Out of memory setting new config filename");
			goto out;
		}
	} else {
		int rc;

		rc = asprintf(&rcfile, "%s/%s/config", lxcpath, my_args.name);
		if (rc == -1) {
			SYSERROR("failed to allocate memory");
			exit(err);
		}
		INFO("using rcfile %s", rcfile);

		/* container configuration does not exist */
		if (access(rcfile, F_OK)) {
			free(rcfile);
			rcfile = NULL;
		}
		c = lxc_container_new(my_args.name, lxcpath);
		if (!c) {
			ERROR("Failed to create lxc_container");
			exit(err);
		}
	}

	/* We do not check here whether the container is defined, because we
	 * support volatile containers. Which means the container does not need
	 * to be created for it to be started. You can just pass a configuration
	 * file as argument and start the container right away.
	 */

	if (!c->may_control(c)) {
		fprintf(stderr, "Insufficent privileges to control %s\n", c->name);
		goto out;
	}

	if (c->is_running(c)) {
		ERROR("Container is already running.");
		err = EXIT_SUCCESS;
		goto out;
	}
	/*
	 * We should use set_config_item() over &defines, which would handle
	 * unset c->lxc_conf for us and let us not use lxc_config_define_load()
	 */
	if (!c->lxc_conf)
		c->lxc_conf = lxc_conf_init();
	conf = c->lxc_conf;

	if (lxc_config_define_load(&defines, conf))
		goto out;

	if (!rcfile && !strcmp("/sbin/init", args[0])) {
		ERROR("Executing '/sbin/init' with no configuration file may crash the host");
		goto out;
	}

	if (ensure_path(&conf->console.path, my_args.console) < 0) {
		ERROR("failed to ensure console path '%s'", my_args.console);
		goto out;
	}

	if (ensure_path(&conf->console.log_path, my_args.console_log) < 0) {
		ERROR("failed to ensure console log '%s'", my_args.console_log);
		goto out;
	}

	if (my_args.pidfile != NULL) {
		if (ensure_path(&c->pidfile, my_args.pidfile) < 0) {
			ERROR("failed to ensure pidfile '%s'", my_args.pidfile);
			goto out;
		}
	}

	int i;
	for (i = 0; i < LXC_NS_MAX; i++) {
		if (my_args.share_ns[i] == NULL)
			continue;

		int pid = pid_from_lxcname(my_args.share_ns[i], lxcpath);
		if (pid < 1)
			goto out;

		int fd = open_ns(pid, ns_info[i].proc_name);
		if (fd < 0)
			goto out;
		conf->inherit_ns_fd[i] = fd;
	}

	if (!my_args.daemonize) {
		c->want_daemonize(c, false);
	}

	if (my_args.close_all_fds)
		c->want_close_all_fds(c, true);

	if (args == default_args)
		err = c->start(c, 0, NULL) ? EXIT_SUCCESS : EXIT_FAILURE;
	else
		err = c->start(c, 0, args) ? EXIT_SUCCESS : EXIT_FAILURE;

	if (err) {
		ERROR("The container failed to start.");
		if (my_args.daemonize)
			ERROR("To get more details, run the container in foreground mode.");
		ERROR("Additional information can be obtained by setting the "
		      "--logfile and --logpriority options.");
		err = c->error_num;
		lxc_container_put(c);
		exit(err);
	}

out:
	lxc_container_put(c);
	exit(err);
}