diff options
author | Luke Shumaker <lukeshu@sbcglobal.net> | 2016-07-27 21:21:19 -0400 |
---|---|---|
committer | Luke Shumaker <lukeshu@sbcglobal.net> | 2016-07-27 21:21:19 -0400 |
commit | 38b93f33c4130a69b6ff1777ee59511f601abff6 (patch) | |
tree | 4f51d827b4e7598b3ab46f86a3c1ab5e03782700 /src/libcore/namespace.c | |
parent | a9330854c56ccba7b6ce4bdb046ae7778b329622 (diff) |
./move.sh
Diffstat (limited to 'src/libcore/namespace.c')
-rw-r--r-- | src/libcore/namespace.c | 650 |
1 files changed, 650 insertions, 0 deletions
diff --git a/src/libcore/namespace.c b/src/libcore/namespace.c new file mode 100644 index 0000000000..203d122810 --- /dev/null +++ b/src/libcore/namespace.c @@ -0,0 +1,650 @@ +/*** + This file is part of systemd. + + Copyright 2010 Lennart Poettering + + systemd 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. + + systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <errno.h> +#include <sched.h> +#include <stdio.h> +#include <string.h> +#include <sys/mount.h> +#include <sys/stat.h> +#include <unistd.h> +#include <linux/fs.h> + +#include "alloc-util.h" +#include "dev-setup.h" +#include "fd-util.h" +#include "loopback-setup.h" +#include "missing.h" +#include "mkdir.h" +#include "mount-util.h" +#include "namespace.h" +#include "path-util.h" +#include "selinux-util.h" +#include "socket-util.h" +#include "string-table.h" +#include "string-util.h" +#include "strv.h" +#include "umask-util.h" +#include "user-util.h" +#include "util.h" + +#define DEV_MOUNT_OPTIONS (MS_NOSUID|MS_STRICTATIME|MS_NOEXEC) + +typedef enum MountMode { + /* This is ordered by priority! */ + INACCESSIBLE, + READONLY, + PRIVATE_TMP, + PRIVATE_VAR_TMP, + PRIVATE_DEV, + READWRITE +} MountMode; + +typedef struct BindMount { + const char *path; + MountMode mode; + bool done; + bool ignore; +} BindMount; + +static int append_mounts(BindMount **p, char **strv, MountMode mode) { + char **i; + + assert(p); + + STRV_FOREACH(i, strv) { + + (*p)->ignore = false; + (*p)->done = false; + + if ((mode == INACCESSIBLE || mode == READONLY || mode == READWRITE) && (*i)[0] == '-') { + (*p)->ignore = true; + (*i)++; + } + + if (!path_is_absolute(*i)) + return -EINVAL; + + (*p)->path = *i; + (*p)->mode = mode; + (*p)++; + } + + return 0; +} + +static int mount_path_compare(const void *a, const void *b) { + const BindMount *p = a, *q = b; + int d; + + d = path_compare(p->path, q->path); + + if (d == 0) { + /* If the paths are equal, check the mode */ + if (p->mode < q->mode) + return -1; + + if (p->mode > q->mode) + return 1; + + return 0; + } + + /* If the paths are not equal, then order prefixes first */ + return d; +} + +static void drop_duplicates(BindMount *m, unsigned *n) { + BindMount *f, *t, *previous; + + assert(m); + assert(n); + + for (f = m, t = m, previous = NULL; f < m+*n; f++) { + + /* The first one wins */ + if (previous && path_equal(f->path, previous->path)) + continue; + + *t = *f; + + previous = t; + + t++; + } + + *n = t - m; +} + +static int mount_dev(BindMount *m) { + static const char devnodes[] = + "/dev/null\0" + "/dev/zero\0" + "/dev/full\0" + "/dev/random\0" + "/dev/urandom\0" + "/dev/tty\0"; + + char temporary_mount[] = "/tmp/namespace-dev-XXXXXX"; + const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL; + _cleanup_umask_ mode_t u; + int r; + + assert(m); + + u = umask(0000); + + if (!mkdtemp(temporary_mount)) + return -errno; + + dev = strjoina(temporary_mount, "/dev"); + (void) mkdir(dev, 0755); + if (mount("tmpfs", dev, "tmpfs", DEV_MOUNT_OPTIONS, "mode=755") < 0) { + r = -errno; + goto fail; + } + + devpts = strjoina(temporary_mount, "/dev/pts"); + (void) mkdir(devpts, 0755); + if (mount("/dev/pts", devpts, NULL, MS_BIND, NULL) < 0) { + r = -errno; + goto fail; + } + + devptmx = strjoina(temporary_mount, "/dev/ptmx"); + if (symlink("pts/ptmx", devptmx) < 0) { + r = -errno; + goto fail; + } + + devshm = strjoina(temporary_mount, "/dev/shm"); + (void) mkdir(devshm, 01777); + r = mount("/dev/shm", devshm, NULL, MS_BIND, NULL); + if (r < 0) { + r = -errno; + goto fail; + } + + devmqueue = strjoina(temporary_mount, "/dev/mqueue"); + (void) mkdir(devmqueue, 0755); + (void) mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL); + + devhugepages = strjoina(temporary_mount, "/dev/hugepages"); + (void) mkdir(devhugepages, 0755); + (void) mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL); + + devlog = strjoina(temporary_mount, "/dev/log"); + (void) symlink("/run/systemd/journal/dev-log", devlog); + + NULSTR_FOREACH(d, devnodes) { + _cleanup_free_ char *dn = NULL; + struct stat st; + + r = stat(d, &st); + if (r < 0) { + + if (errno == ENOENT) + continue; + + r = -errno; + goto fail; + } + + if (!S_ISBLK(st.st_mode) && + !S_ISCHR(st.st_mode)) { + r = -EINVAL; + goto fail; + } + + if (st.st_rdev == 0) + continue; + + dn = strappend(temporary_mount, d); + if (!dn) { + r = -ENOMEM; + goto fail; + } + + mac_selinux_create_file_prepare(d, st.st_mode); + r = mknod(dn, st.st_mode, st.st_rdev); + mac_selinux_create_file_clear(); + + if (r < 0) { + r = -errno; + goto fail; + } + } + + dev_setup(temporary_mount, UID_INVALID, GID_INVALID); + + /* Create the /dev directory if missing. It is more likely to be + * missing when the service is started with RootDirectory. This is + * consistent with mount units creating the mount points when missing. + */ + (void) mkdir_p_label(m->path, 0755); + + /* Unmount everything in old /dev */ + umount_recursive(m->path, 0); + if (mount(dev, m->path, NULL, MS_MOVE, NULL) < 0) { + r = -errno; + goto fail; + } + + rmdir(dev); + rmdir(temporary_mount); + + return 0; + +fail: + if (devpts) + umount(devpts); + + if (devshm) + umount(devshm); + + if (devhugepages) + umount(devhugepages); + + if (devmqueue) + umount(devmqueue); + + umount(dev); + rmdir(dev); + rmdir(temporary_mount); + + return r; +} + +static int apply_mount( + BindMount *m, + const char *tmp_dir, + const char *var_tmp_dir) { + + const char *what; + int r; + + assert(m); + + switch (m->mode) { + + case INACCESSIBLE: + + /* First, get rid of everything that is below if there + * is anything... Then, overmount it with an + * inaccessible directory. */ + umount_recursive(m->path, 0); + + what = "/run/systemd/inaccessible"; + break; + + case READONLY: + case READWRITE: + /* Nothing to mount here, we just later toggle the + * MS_RDONLY bit for the mount point */ + return 0; + + case PRIVATE_TMP: + what = tmp_dir; + break; + + case PRIVATE_VAR_TMP: + what = var_tmp_dir; + break; + + case PRIVATE_DEV: + return mount_dev(m); + + default: + assert_not_reached("Unknown mode"); + } + + assert(what); + + r = mount(what, m->path, NULL, MS_BIND|MS_REC, NULL); + if (r >= 0) + log_debug("Successfully mounted %s to %s", what, m->path); + else if (m->ignore && errno == ENOENT) + return 0; + + return r; +} + +static int make_read_only(BindMount *m) { + int r; + + assert(m); + + if (IN_SET(m->mode, INACCESSIBLE, READONLY)) + r = bind_remount_recursive(m->path, true); + else if (IN_SET(m->mode, READWRITE, PRIVATE_TMP, PRIVATE_VAR_TMP, PRIVATE_DEV)) { + r = bind_remount_recursive(m->path, false); + if (r == 0 && m->mode == PRIVATE_DEV) /* can be readonly but the submounts can't*/ + r = mount(NULL, m->path, NULL, MS_REMOUNT|DEV_MOUNT_OPTIONS|MS_RDONLY, NULL); + } else + r = 0; + + if (m->ignore && r == -ENOENT) + return 0; + + return r; +} + +int setup_namespace( + const char* root_directory, + char** read_write_dirs, + char** read_only_dirs, + char** inaccessible_dirs, + const char* tmp_dir, + const char* var_tmp_dir, + bool private_dev, + ProtectHome protect_home, + ProtectSystem protect_system, + unsigned long mount_flags) { + + BindMount *m, *mounts = NULL; + unsigned n; + int r = 0; + + if (mount_flags == 0) + mount_flags = MS_SHARED; + + if (unshare(CLONE_NEWNS) < 0) + return -errno; + + n = !!tmp_dir + !!var_tmp_dir + + strv_length(read_write_dirs) + + strv_length(read_only_dirs) + + strv_length(inaccessible_dirs) + + private_dev + + (protect_home != PROTECT_HOME_NO ? 3 : 0) + + (protect_system != PROTECT_SYSTEM_NO ? 2 : 0) + + (protect_system == PROTECT_SYSTEM_FULL ? 1 : 0); + + if (n > 0) { + m = mounts = (BindMount *) alloca0(n * sizeof(BindMount)); + r = append_mounts(&m, read_write_dirs, READWRITE); + if (r < 0) + return r; + + r = append_mounts(&m, read_only_dirs, READONLY); + if (r < 0) + return r; + + r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE); + if (r < 0) + return r; + + if (tmp_dir) { + m->path = prefix_roota(root_directory, "/tmp"); + m->mode = PRIVATE_TMP; + m++; + } + + if (var_tmp_dir) { + m->path = prefix_roota(root_directory, "/var/tmp"); + m->mode = PRIVATE_VAR_TMP; + m++; + } + + if (private_dev) { + m->path = prefix_roota(root_directory, "/dev"); + m->mode = PRIVATE_DEV; + m++; + } + + if (protect_home != PROTECT_HOME_NO) { + const char *home_dir, *run_user_dir, *root_dir; + + home_dir = prefix_roota(root_directory, "/home"); + home_dir = strjoina("-", home_dir); + run_user_dir = prefix_roota(root_directory, "/run/user"); + run_user_dir = strjoina("-", run_user_dir); + root_dir = prefix_roota(root_directory, "/root"); + root_dir = strjoina("-", root_dir); + + r = append_mounts(&m, STRV_MAKE(home_dir, run_user_dir, root_dir), + protect_home == PROTECT_HOME_READ_ONLY ? READONLY : INACCESSIBLE); + if (r < 0) + return r; + } + + if (protect_system != PROTECT_SYSTEM_NO) { + const char *usr_dir, *boot_dir, *etc_dir; + + usr_dir = prefix_roota(root_directory, "/usr"); + boot_dir = prefix_roota(root_directory, "/boot"); + boot_dir = strjoina("-", boot_dir); + etc_dir = prefix_roota(root_directory, "/etc"); + + r = append_mounts(&m, protect_system == PROTECT_SYSTEM_FULL + ? STRV_MAKE(usr_dir, boot_dir, etc_dir) + : STRV_MAKE(usr_dir, boot_dir), READONLY); + if (r < 0) + return r; + } + + assert(mounts + n == m); + + qsort(mounts, n, sizeof(BindMount), mount_path_compare); + drop_duplicates(mounts, &n); + } + + if (n > 0 || root_directory) { + /* Remount / as SLAVE so that nothing now mounted in the namespace + shows up in the parent */ + if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) + return -errno; + } + + if (root_directory) { + /* Turn directory into bind mount */ + if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0) + return -errno; + } + + if (n > 0) { + for (m = mounts; m < mounts + n; ++m) { + r = apply_mount(m, tmp_dir, var_tmp_dir); + if (r < 0) + goto fail; + } + + for (m = mounts; m < mounts + n; ++m) { + r = make_read_only(m); + if (r < 0) + goto fail; + } + } + + if (root_directory) { + /* MS_MOVE does not work on MS_SHARED so the remount MS_SHARED will be done later */ + r = mount_move_root(root_directory); + + /* at this point, we cannot rollback */ + if (r < 0) + return r; + } + + /* Remount / as the desired mode. Not that this will not + * reestablish propagation from our side to the host, since + * what's disconnected is disconnected. */ + if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) + /* at this point, we cannot rollback */ + return -errno; + + return 0; + +fail: + if (n > 0) { + for (m = mounts; m < mounts + n; ++m) + if (m->done) + (void) umount2(m->path, MNT_DETACH); + } + + return r; +} + +static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) { + _cleanup_free_ char *x = NULL; + char bid[SD_ID128_STRING_MAX]; + sd_id128_t boot_id; + int r; + + assert(id); + assert(prefix); + assert(path); + + /* We include the boot id in the directory so that after a + * reboot we can easily identify obsolete directories. */ + + r = sd_id128_get_boot(&boot_id); + if (r < 0) + return r; + + x = strjoin(prefix, "/systemd-private-", sd_id128_to_string(boot_id, bid), "-", id, "-XXXXXX", NULL); + if (!x) + return -ENOMEM; + + RUN_WITH_UMASK(0077) + if (!mkdtemp(x)) + return -errno; + + RUN_WITH_UMASK(0000) { + char *y; + + y = strjoina(x, "/tmp"); + + if (mkdir(y, 0777 | S_ISVTX) < 0) + return -errno; + } + + *path = x; + x = NULL; + + return 0; +} + +int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) { + char *a, *b; + int r; + + assert(id); + assert(tmp_dir); + assert(var_tmp_dir); + + r = setup_one_tmp_dir(id, "/tmp", &a); + if (r < 0) + return r; + + r = setup_one_tmp_dir(id, "/var/tmp", &b); + if (r < 0) { + char *t; + + t = strjoina(a, "/tmp"); + rmdir(t); + rmdir(a); + + free(a); + return r; + } + + *tmp_dir = a; + *var_tmp_dir = b; + + return 0; +} + +int setup_netns(int netns_storage_socket[2]) { + _cleanup_close_ int netns = -1; + int r, q; + + assert(netns_storage_socket); + assert(netns_storage_socket[0] >= 0); + assert(netns_storage_socket[1] >= 0); + + /* We use the passed socketpair as a storage buffer for our + * namespace reference fd. Whatever process runs this first + * shall create a new namespace, all others should just join + * it. To serialize that we use a file lock on the socket + * pair. + * + * It's a bit crazy, but hey, works great! */ + + if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0) + return -errno; + + netns = receive_one_fd(netns_storage_socket[0], MSG_DONTWAIT); + if (netns == -EAGAIN) { + /* Nothing stored yet, so let's create a new namespace */ + + if (unshare(CLONE_NEWNET) < 0) { + r = -errno; + goto fail; + } + + loopback_setup(); + + netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (netns < 0) { + r = -errno; + goto fail; + } + + r = 1; + + } else if (netns < 0) { + r = netns; + goto fail; + + } else { + /* Yay, found something, so let's join the namespace */ + if (setns(netns, CLONE_NEWNET) < 0) { + r = -errno; + goto fail; + } + + r = 0; + } + + q = send_one_fd(netns_storage_socket[1], netns, MSG_DONTWAIT); + if (q < 0) { + r = q; + goto fail; + } + +fail: + lockf(netns_storage_socket[0], F_ULOCK, 0); + return r; +} + +static const char *const protect_home_table[_PROTECT_HOME_MAX] = { + [PROTECT_HOME_NO] = "no", + [PROTECT_HOME_YES] = "yes", + [PROTECT_HOME_READ_ONLY] = "read-only", +}; + +DEFINE_STRING_TABLE_LOOKUP(protect_home, ProtectHome); + +static const char *const protect_system_table[_PROTECT_SYSTEM_MAX] = { + [PROTECT_SYSTEM_NO] = "no", + [PROTECT_SYSTEM_YES] = "yes", + [PROTECT_SYSTEM_FULL] = "full", +}; + +DEFINE_STRING_TABLE_LOOKUP(protect_system, ProtectSystem); |