X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fnspawn%2Fnspawn.c;h=fec39d644875e816a11ea1468414dd7638fb47b8;hb=94f7a71442bda7c43191979ea13cc97112745ce4;hp=685b4d4e50d4b5c588ebd8374d028b2cb83b046b;hpb=dce818b390a857a11f7dd634684500675cf79833;p=elogind.git diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 685b4d4e5..fec39d644 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -38,6 +38,8 @@ #include #include #include +#include +#include #include @@ -48,12 +50,16 @@ #include "missing.h" #include "cgroup-util.h" #include "strv.h" +#include "path-util.h" #include "loopback-setup.h" static char *arg_directory = NULL; static char *arg_user = NULL; static char **arg_controllers = NULL; +static char *arg_uuid = NULL; static bool arg_private_network = false; +static bool arg_read_only = false; +static bool arg_boot = false; static int help(void) { @@ -61,9 +67,12 @@ static int help(void) { "Spawn a minimal namespace container for debugging, testing and building.\n\n" " -h --help Show this help\n" " -D --directory=NAME Root directory for the container\n" + " -b --boot Boot up full system (i.e. invoke init)\n" " -u --user=USER Run the command under specified user or uid\n" " -C --controllers=LIST Put the container in specified comma-separated cgroup hierarchies\n" - " --private-network Disable network in container\n", + " --uuid=UUID Set a specific machine UUID for the container\n" + " --private-network Disable network in container\n" + " --read-only Mount the root directory read-only\n", program_invocation_short_name); return 0; @@ -72,7 +81,9 @@ static int help(void) { static int parse_argv(int argc, char *argv[]) { enum { - ARG_PRIVATE_NETWORK = 0x100 + ARG_PRIVATE_NETWORK = 0x100, + ARG_UUID, + ARG_READ_ONLY }; static const struct option options[] = { @@ -81,6 +92,9 @@ static int parse_argv(int argc, char *argv[]) { { "user", required_argument, NULL, 'u' }, { "controllers", required_argument, NULL, 'C' }, { "private-network", no_argument, NULL, ARG_PRIVATE_NETWORK }, + { "boot", no_argument, NULL, 'b' }, + { "uuid", required_argument, NULL, ARG_UUID }, + { "read-only", no_argument, NULL, ARG_READ_ONLY }, { NULL, 0, NULL, 0 } }; @@ -89,7 +103,7 @@ static int parse_argv(int argc, char *argv[]) { assert(argc >= 0); assert(argv); - while ((c = getopt_long(argc, argv, "+hD:u:C:", options, NULL)) >= 0) { + while ((c = getopt_long(argc, argv, "+hD:u:C:b", options, NULL)) >= 0) { switch (c) { @@ -99,8 +113,9 @@ static int parse_argv(int argc, char *argv[]) { case 'D': free(arg_directory); - if (!(arg_directory = strdup(optarg))) { - log_error("Failed to duplicate root directory."); + arg_directory = canonicalize_file_name(optarg); + if (!arg_directory) { + log_error("Failed to canonicalize root directory."); return -ENOMEM; } @@ -130,6 +145,18 @@ static int parse_argv(int argc, char *argv[]) { arg_private_network = true; break; + case 'b': + arg_boot = true; + break; + + case ARG_UUID: + arg_uuid = optarg; + break; + + case ARG_READ_ONLY: + arg_read_only = true; + break; + case '?': return -EINVAL; @@ -195,7 +222,7 @@ static int mount_all(const char *dest) { continue; } - mkdir_p(where, 0755); + mkdir_p_label(where, 0755); if (mount(mount_table[k].what, where, @@ -213,32 +240,61 @@ static int mount_all(const char *dest) { free(where); } - /* Fix the timezone, if possible */ - if (asprintf(&where, "%s/etc/localtime", dest) >= 0) { + return r; +} + +static int setup_timezone(const char *dest) { + char *where; - if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0) - mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); + assert(dest); - free(where); + /* Fix the timezone, if possible */ + if (asprintf(&where, "%s/etc/localtime", dest) < 0) { + log_error("Out of memory"); + return -ENOMEM; } - if (asprintf(&where, "%s/etc/timezone", dest) >= 0) { + if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0) + mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); - if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0) - mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); + free(where); - free(where); + if (asprintf(&where, "%s/etc/timezone", dest) < 0) { + log_error("Out of memory"); + return -ENOMEM; } - if (asprintf(&where, "%s/proc/kmsg", dest) >= 0) { - mount("/dev/null", where, "bind", MS_BIND, NULL); - free(where); + if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0) + mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); + + free(where); + + return 0; +} + +static int setup_resolv_conf(const char *dest) { + char *where; + + assert(dest); + + if (arg_private_network) + return 0; + + /* Fix resolv.conf, if possible */ + if (asprintf(&where, "%s/etc/resolv.conf", dest) < 0) { + log_error("Out of memory"); + return -ENOMEM; } - return r; + if (mount("/etc/resolv.conf", where, "bind", MS_BIND, NULL) >= 0) + mount("/etc/resolv.conf", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); + + free(where); + + return 0; } -static int copy_devnodes(const char *dest, const char *console) { +static int copy_devnodes(const char *dest) { static const char devnodes[] = "null\0" @@ -248,22 +304,19 @@ static int copy_devnodes(const char *dest, const char *console) { "urandom\0" "tty\0" "ptmx\0" - "kmsg\0" "rtc0\0"; const char *d; - int r = 0, k; + int r = 0; mode_t u; - struct stat st; - char *from = NULL, *to = NULL; assert(dest); - assert(console); u = umask(0000); NULSTR_FOREACH(d, devnodes) { - from = to = NULL; + struct stat st; + char *from = NULL, *to = NULL; asprintf(&from, "/dev/%s", d); asprintf(&to, "%s/dev/%s", dest, d); @@ -307,30 +360,43 @@ static int copy_devnodes(const char *dest, const char *console) { free(to); } - if (stat(console, &st) < 0) { + umask(u); - log_error("Failed to stat %s: %m", console); - if (r == 0) - r = -errno; + return r; +} + +static int setup_dev_console(const char *dest, const char *console) { + struct stat st; + char *to = NULL; + int r; + mode_t u; + + assert(dest); + assert(console); + + u = umask(0000); + if (stat(console, &st) < 0) { + log_error("Failed to stat %s: %m", console); + r = -errno; goto finish; } else if (!S_ISCHR(st.st_mode)) { - log_error("/dev/console is not a char device."); - if (r == 0) - r = -EIO; + r = -EIO; + goto finish; + } + r = chmod_and_chown(console, 0600, 0, 0); + if (r < 0) { + log_error("Failed to correct access mode for TTY: %s", strerror(-r)); goto finish; } if (asprintf(&to, "%s/dev/console", dest) < 0) { - log_error("Out of memory"); - if (r == 0) - r = -ENOMEM; - - goto finish; + r = -ENOMEM; + goto finish; } /* We need to bind mount the right tty to /dev/console since @@ -340,75 +406,169 @@ static int copy_devnodes(const char *dest, const char *console) { * doesn't actually matter here, since we mount it over * anyway). */ - if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) - log_error("mknod for /dev/console failed: %m"); + if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) { + log_error("mknod() for /dev/console failed: %m"); + r = -errno; + goto finish; + } if (mount(console, to, "bind", MS_BIND, NULL) < 0) { - log_error("bind mount for /dev/console failed: %m"); - - if (r == 0) - r = -errno; + log_error("Bind mount for /dev/console failed: %m"); + r = -errno; + goto finish; } +finish: free(to); + umask(u); + + return r; +} + +static int setup_kmsg(const char *dest, int kmsg_socket) { + char *from = NULL, *to = NULL; + int r, fd, k; + mode_t u; + union { + struct cmsghdr cmsghdr; + uint8_t buf[CMSG_SPACE(sizeof(int))]; + } control; + struct msghdr mh; + struct cmsghdr *cmsg; + + assert(dest); + assert(kmsg_socket >= 0); + + u = umask(0000); + + /* We create the kmsg FIFO as /dev/kmsg, but immediately + * delete it after bind mounting it to /proc/kmsg. While FIFOs + * on the reading side behave very similar to /proc/kmsg, + * their writing side behaves differently from /dev/kmsg in + * that writing blocks when nothing is reading. In order to + * avoid any problems with containers deadlocking due to this + * we simply make /dev/kmsg unavailable to the container. */ + if (asprintf(&from, "%s/dev/kmsg", dest) < 0) { + log_error("Out of memory"); + r = -ENOMEM; + goto finish; + } + + if (asprintf(&to, "%s/proc/kmsg", dest) < 0) { + log_error("Out of memory"); + r = -ENOMEM; + goto finish; + } - if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) { - log_error("Failed to correct access mode for TTY: %s", strerror(-k)); + if (mkfifo(from, 0600) < 0) { + log_error("mkfifo() for /dev/kmsg failed: %m"); + r = -errno; + goto finish; + } - if (r == 0) - r = k; + r = chmod_and_chown(from, 0600, 0, 0); + if (r < 0) { + log_error("Failed to correct access mode for /dev/kmsg: %s", strerror(-r)); + goto finish; } + if (mount(from, to, "bind", MS_BIND, NULL) < 0) { + log_error("Bind mount for /proc/kmsg failed: %m"); + r = -errno; + goto finish; + } + + fd = open(from, O_RDWR|O_NDELAY|O_CLOEXEC); + if (fd < 0) { + log_error("Failed to open fifo: %m"); + r = -errno; + goto finish; + } + + zero(mh); + zero(control); + + mh.msg_control = &control; + mh.msg_controllen = sizeof(control); + + cmsg = CMSG_FIRSTHDR(&mh); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &fd, sizeof(int)); + + mh.msg_controllen = cmsg->cmsg_len; + + /* Store away the fd in the socket, so that it stays open as + * long as we run the child */ + k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL); + close_nointr_nofail(fd); + + if (k < 0) { + log_error("Failed to send FIFO fd: %m"); + r = -errno; + goto finish; + } + + /* And now make the FIFO unavailable as /dev/kmsg... */ + unlink(from); + finish: + free(from); + free(to); umask(u); return r; } -static int drop_capabilities(void) { - static const unsigned long retain[] = { - CAP_CHOWN, - CAP_DAC_OVERRIDE, - CAP_DAC_READ_SEARCH, - CAP_FOWNER, - CAP_FSETID, - CAP_IPC_OWNER, - CAP_KILL, - CAP_LEASE, - CAP_LINUX_IMMUTABLE, - CAP_NET_BIND_SERVICE, - CAP_NET_BROADCAST, - CAP_NET_RAW, - CAP_SETGID, - CAP_SETFCAP, - CAP_SETPCAP, - CAP_SETUID, - CAP_SYS_ADMIN, - CAP_SYS_CHROOT, - CAP_SYS_NICE, - CAP_SYS_PTRACE, - CAP_SYS_TTY_CONFIG - }; - - unsigned long l; +static int setup_hostname(void) { + char *hn; + int r = 0; - for (l = 0; l <= cap_last_cap(); l++) { - unsigned i; + hn = path_get_file_name(arg_directory); + if (hn) { + hn = strdup(hn); + if (!hn) + return -ENOMEM; - for (i = 0; i < ELEMENTSOF(retain); i++) - if (retain[i] == l) - break; + hostname_cleanup(hn); - if (i < ELEMENTSOF(retain)) - continue; + if (!isempty(hn)) + if (sethostname(hn, strlen(hn)) < 0) + r = -errno; - if (prctl(PR_CAPBSET_DROP, l) < 0) { - log_error("PR_CAPBSET_DROP failed: %m"); - return -errno; - } + free(hn); } - return 0; + return r; +} + +static int drop_capabilities(void) { + + static const uint64_t retain = + (1ULL << CAP_CHOWN) | + (1ULL << CAP_DAC_OVERRIDE) | + (1ULL << CAP_DAC_READ_SEARCH) | + (1ULL << CAP_FOWNER) | + (1ULL << CAP_FSETID) | + (1ULL << CAP_IPC_OWNER) | + (1ULL << CAP_KILL) | + (1ULL << CAP_LEASE) | + (1ULL << CAP_LINUX_IMMUTABLE) | + (1ULL << CAP_NET_BIND_SERVICE) | + (1ULL << CAP_NET_BROADCAST) | + (1ULL << CAP_NET_RAW) | + (1ULL << CAP_SETGID) | + (1ULL << CAP_SETFCAP) | + (1ULL << CAP_SETPCAP) | + (1ULL << CAP_SETUID) | + (1ULL << CAP_SYS_ADMIN) | + (1ULL << CAP_SYS_CHROOT) | + (1ULL << CAP_SYS_NICE) | + (1ULL << CAP_SYS_PTRACE) | + (1ULL << CAP_SYS_TTY_CONFIG); + + return capability_bounding_set_drop(~retain, false); } static int is_os_tree(const char *path) { @@ -639,6 +799,7 @@ int main(int argc, char *argv[]) { sigset_t mask; bool saved_attr_valid = false; struct winsize ws; + int kmsg_socket_pair[2] = { -1, -1 }; log_parse_environment(); log_open(); @@ -740,6 +901,11 @@ int main(int argc, char *argv[]) { goto finish; } + if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) { + log_error("Failed to create kmsg socket pair"); + goto finish; + } + assert_se(sigemptyset(&mask) == 0); sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1); assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0); @@ -757,7 +923,6 @@ int main(int argc, char *argv[]) { if (pid == 0) { /* child */ - const char *hn; const char *home = NULL; uid_t uid = (uid_t) -1; gid_t gid = (gid_t) -1; @@ -768,6 +933,7 @@ int main(int argc, char *argv[]) { NULL, /* HOME */ NULL, /* USER */ NULL, /* LOGNAME */ + NULL, /* container_uuid */ NULL }; @@ -779,7 +945,7 @@ int main(int argc, char *argv[]) { close_nointr(STDOUT_FILENO); close_nointr(STDERR_FILENO); - close_all_fds(NULL, 0); + close_all_fds(&kmsg_socket_pair[1], 1); reset_all_signal_handlers(); @@ -796,10 +962,36 @@ int main(int argc, char *argv[]) { if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) goto child_fail; + /* Turn directory into bind mount */ + if (mount(arg_directory, arg_directory, "bind", MS_BIND, NULL) < 0) { + log_error("Failed to make bind mount."); + goto child_fail; + } + + if (arg_read_only) + if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) { + log_error("Failed to make read-only."); + goto child_fail; + } + if (mount_all(arg_directory) < 0) goto child_fail; - if (copy_devnodes(arg_directory, console) < 0) + if (copy_devnodes(arg_directory) < 0) + goto child_fail; + + if (setup_dev_console(arg_directory, console) < 0) + goto child_fail; + + if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0) + goto child_fail; + + close_nointr_nofail(kmsg_socket_pair[1]); + + if (setup_timezone(arg_directory) < 0) + goto child_fail; + + if (setup_resolv_conf(arg_directory) < 0) goto child_fail; if (chdir(arg_directory) < 0) { @@ -812,8 +1004,8 @@ int main(int argc, char *argv[]) { dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO) goto child_fail; - if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) { - log_error("mount(MS_MOVE) failed: %m"); + if (mount(arg_directory, "/", "bind", MS_MOVE, NULL) < 0) { + log_error("mount(MS_BIND) failed: %m"); goto child_fail; } @@ -831,8 +1023,10 @@ int main(int argc, char *argv[]) { loopback_setup(); - if (drop_capabilities() < 0) + if (drop_capabilities() < 0) { + log_error("drop_capabilities() failed: %m"); goto child_fail; + } if (arg_user) { @@ -841,13 +1035,13 @@ int main(int argc, char *argv[]) { goto child_fail; } - if (mkdir_parents(home, 0775) < 0) { - log_error("mkdir_parents() failed: %m"); + if (mkdir_parents_label(home, 0775) < 0) { + log_error("mkdir_parents_label() failed: %m"); goto child_fail; } - if (safe_mkdir(home, 0775, uid, gid) < 0) { - log_error("safe_mkdir() failed: %m"); + if (mkdir_safe_label(home, 0775, uid, gid) < 0) { + log_error("mkdir_safe_label() failed: %m"); goto child_fail; } @@ -867,17 +1061,41 @@ int main(int argc, char *argv[]) { } } - if ((asprintf((char**)(envp + 3), "HOME=%s", home? home: "/root") < 0) || - (asprintf((char**)(envp + 4), "USER=%s", arg_user? arg_user : "root") < 0) || - (asprintf((char**)(envp + 5), "LOGNAME=%s", arg_user? arg_user : "root") < 0)) { + if ((asprintf((char**)(envp + 3), "HOME=%s", home ? home: "/root") < 0) || + (asprintf((char**)(envp + 4), "USER=%s", arg_user ? arg_user : "root") < 0) || + (asprintf((char**)(envp + 5), "LOGNAME=%s", arg_user ? arg_user : "root") < 0)) { log_error("Out of memory"); goto child_fail; } - if ((hn = file_name_from_path(arg_directory))) - sethostname(hn, strlen(hn)); + if (arg_uuid) { + if (asprintf((char**)(envp + 6), "container_uuid=%s", arg_uuid) < 0) { + log_error("Out of memory"); + goto child_fail; + } + } + + setup_hostname(); + + if (arg_boot) { + char **a; + size_t l; + + /* Automatically search for the init system */ - if (argc > optind) + l = 1 + argc - optind; + a = newa(char*, l + 1); + memcpy(a + 1, argv + optind, l * sizeof(char*)); + + a[0] = (char*) "/usr/lib/systemd/systemd"; + execve(a[0], a, (char**) envp); + + a[0] = (char*) "/lib/systemd/systemd"; + execve(a[0], a, (char**) envp); + + a[0] = (char*) "/sbin/init"; + execve(a[0], a, (char**) envp); + } else if (argc > optind) execvpe(argv[optind], argv + optind, (char**) envp); else { chdir(home ? home : "/root"); @@ -910,6 +1128,8 @@ finish: if (master >= 0) close_nointr_nofail(master); + close_pipe(kmsg_socket_pair); + if (oldcg) cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);