diff options
Diffstat (limited to 'src/grp-system/libcore/src/namespace.c')
| -rw-r--r-- | src/grp-system/libcore/src/namespace.c | 1044 |
1 files changed, 1044 insertions, 0 deletions
diff --git a/src/grp-system/libcore/src/namespace.c b/src/grp-system/libcore/src/namespace.c new file mode 100644 index 0000000000..988516d775 --- /dev/null +++ b/src/grp-system/libcore/src/namespace.c @@ -0,0 +1,1044 @@ +/*** + 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 "core/loopback-setup.h" +#include "core/namespace.h" +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/fd-util.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/missing.h" +#include "systemd-basic/mkdir.h" +#include "systemd-basic/mount-util.h" +#include "systemd-basic/path-util.h" +#include "systemd-basic/selinux-util.h" +#include "systemd-basic/socket-util.h" +#include "systemd-basic/string-table.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/strv.h" +#include "systemd-basic/umask-util.h" +#include "systemd-basic/user-util.h" +#include "systemd-basic/util.h" +#include "systemd-shared/dev-setup.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; /* stack memory, doesn't need to be freed explicitly */ + char *chased; /* malloc()ed memory, needs to be freed */ + MountMode mode; + bool ignore; /* Ignore if path does not exist */ +} BindMount; + +typedef struct TargetMount { + const char *path; + MountMode mode; + bool ignore; /* Ignore if path does not exist */ +} TargetMount; + +/* + * The following Protect tables are to protect paths and mark some of them + * READONLY, in case a path is covered by an option from another table, then + * it is marked READWRITE in the current one, and the more restrictive mode is + * applied from that other table. This way all options can be combined in a + * safe and comprehensible way for users. + */ + +/* ProtectKernelTunables= option and the related filesystem APIs */ +static const TargetMount protect_kernel_tunables_table[] = { + { "/proc/sys", READONLY, false }, + { "/proc/sysrq-trigger", READONLY, true }, + { "/proc/latency_stats", READONLY, true }, + { "/proc/mtrr", READONLY, true }, + { "/proc/apm", READONLY, true }, + { "/proc/acpi", READONLY, true }, + { "/proc/timer_stats", READONLY, true }, + { "/proc/asound", READONLY, true }, + { "/proc/bus", READONLY, true }, + { "/proc/fs", READONLY, true }, + { "/proc/irq", READONLY, true }, + { "/sys", READONLY, false }, + { "/sys/kernel/debug", READONLY, true }, + { "/sys/kernel/tracing", READONLY, true }, + { "/sys/fs/cgroup", READWRITE, false }, /* READONLY is set by ProtectControlGroups= option */ +}; + +/* ProtectKernelModules= option */ +static const TargetMount protect_kernel_modules_table[] = { +#ifdef HAVE_SPLIT_USR + { "/lib/modules", INACCESSIBLE, true }, +#endif + { "/usr/lib/modules", INACCESSIBLE, true }, +}; + +/* + * ProtectHome=read-only table, protect $HOME and $XDG_RUNTIME_DIR and rest of + * system should be protected by ProtectSystem= + */ +static const TargetMount protect_home_read_only_table[] = { + { "/home", READONLY, true }, + { "/run/user", READONLY, true }, + { "/root", READONLY, true }, +}; + +/* ProtectHome=yes table */ +static const TargetMount protect_home_yes_table[] = { + { "/home", INACCESSIBLE, true }, + { "/run/user", INACCESSIBLE, true }, + { "/root", INACCESSIBLE, true }, +}; + +/* ProtectSystem=yes table */ +static const TargetMount protect_system_yes_table[] = { + { "/usr", READONLY, false }, + { "/boot", READONLY, true }, + { "/efi", READONLY, true }, +}; + +/* ProtectSystem=full includes ProtectSystem=yes */ +static const TargetMount protect_system_full_table[] = { + { "/usr", READONLY, false }, + { "/boot", READONLY, true }, + { "/efi", READONLY, true }, + { "/etc", READONLY, false }, +}; + +/* + * ProtectSystem=strict table. In this strict mode, we mount everything + * read-only, except for /proc, /dev, /sys which are the kernel API VFS, + * which are left writable, but PrivateDevices= + ProtectKernelTunables= + * protect those, and these options should be fully orthogonal. + * (And of course /home and friends are also left writable, as ProtectHome= + * shall manage those, orthogonally). + */ +static const TargetMount protect_system_strict_table[] = { + { "/", READONLY, false }, + { "/proc", READWRITE, false }, /* ProtectKernelTunables= */ + { "/sys", READWRITE, false }, /* ProtectKernelTunables= */ + { "/dev", READWRITE, false }, /* PrivateDevices= */ + { "/home", READWRITE, true }, /* ProtectHome= */ + { "/run/user", READWRITE, true }, /* ProtectHome= */ + { "/root", READWRITE, true }, /* ProtectHome= */ +}; + +static void set_bind_mount(BindMount **p, const char *path, MountMode mode, bool ignore) { + (*p)->path = path; + (*p)->mode = mode; + (*p)->ignore = ignore; +} + +static int append_mounts(BindMount **p, char **strv, MountMode mode) { + char **i; + + assert(p); + + STRV_FOREACH(i, strv) { + bool ignore = false; + + if (IN_SET(mode, INACCESSIBLE, READONLY, READWRITE) && startswith(*i, "-")) { + (*i)++; + ignore = true; + } + + if (!path_is_absolute(*i)) + return -EINVAL; + + set_bind_mount(p, *i, mode, ignore); + (*p)++; + } + + return 0; +} + +static int append_target_mounts(BindMount **p, const char *root_directory, const TargetMount *mounts, const size_t size) { + unsigned i; + + assert(p); + assert(mounts); + + for (i = 0; i < size; i++) { + /* + * Here we assume that the ignore field is set during + * declaration we do not support "-" at the beginning. + */ + const TargetMount *m = &mounts[i]; + const char *path = prefix_roota(root_directory, m->path); + + if (!path_is_absolute(path)) + return -EINVAL; + + set_bind_mount(p, path, m->mode, m->ignore); + (*p)++; + } + + return 0; +} + +static int append_protect_kernel_tunables(BindMount **p, const char *root_directory) { + assert(p); + + return append_target_mounts(p, root_directory, protect_kernel_tunables_table, + ELEMENTSOF(protect_kernel_tunables_table)); +} + +static int append_protect_kernel_modules(BindMount **p, const char *root_directory) { + assert(p); + + return append_target_mounts(p, root_directory, protect_kernel_modules_table, + ELEMENTSOF(protect_kernel_modules_table)); +} + +static int append_protect_home(BindMount **p, const char *root_directory, ProtectHome protect_home) { + int r = 0; + + assert(p); + + if (protect_home == PROTECT_HOME_NO) + return 0; + + switch (protect_home) { + case PROTECT_HOME_READ_ONLY: + r = append_target_mounts(p, root_directory, protect_home_read_only_table, + ELEMENTSOF(protect_home_read_only_table)); + break; + case PROTECT_HOME_YES: + r = append_target_mounts(p, root_directory, protect_home_yes_table, + ELEMENTSOF(protect_home_yes_table)); + break; + default: + r = -EINVAL; + break; + } + + return r; +} + +static int append_protect_system(BindMount **p, const char *root_directory, ProtectSystem protect_system) { + int r = 0; + + assert(p); + + if (protect_system == PROTECT_SYSTEM_NO) + return 0; + + switch (protect_system) { + case PROTECT_SYSTEM_STRICT: + r = append_target_mounts(p, root_directory, protect_system_strict_table, + ELEMENTSOF(protect_system_strict_table)); + break; + case PROTECT_SYSTEM_YES: + r = append_target_mounts(p, root_directory, protect_system_yes_table, + ELEMENTSOF(protect_system_yes_table)); + break; + case PROTECT_SYSTEM_FULL: + r = append_target_mounts(p, root_directory, protect_system_full_table, + ELEMENTSOF(protect_system_full_table)); + break; + default: + r = -EINVAL; + break; + } + + return r; +} + +static int mount_path_compare(const void *a, const void *b) { + const BindMount *p = a, *q = b; + int d; + + /* If the paths are not equal, then order prefixes first */ + d = path_compare(p->path, q->path); + if (d != 0) + return d; + + /* If the paths are equal, check the mode */ + if (p->mode < q->mode) + return -1; + + if (p->mode > q->mode) + return 1; + + return 0; +} + +static void drop_duplicates(BindMount *m, unsigned *n) { + BindMount *f, *t, *previous; + + assert(m); + assert(n); + + /* Drops duplicate entries. Expects that the array is properly ordered already. */ + + for (f = m, t = m, previous = NULL; f < m+*n; f++) { + + /* The first one wins (which is the one with the more restrictive mode), see mount_path_compare() + * above. */ + if (previous && path_equal(f->path, previous->path)) { + log_debug("%s is duplicate.", f->path); + continue; + } + + *t = *f; + previous = t; + t++; + } + + *n = t - m; +} + +static void drop_inaccessible(BindMount *m, unsigned *n) { + BindMount *f, *t; + const char *clear = NULL; + + assert(m); + assert(n); + + /* Drops all entries obstructed by another entry further up the tree. Expects that the array is properly + * ordered already. */ + + for (f = m, t = m; f < m+*n; f++) { + + /* If we found a path set for INACCESSIBLE earlier, and this entry has it as prefix we should drop + * it, as inaccessible paths really should drop the entire subtree. */ + if (clear && path_startswith(f->path, clear)) { + log_debug("%s is masked by %s.", f->path, clear); + continue; + } + + clear = f->mode == INACCESSIBLE ? f->path : NULL; + + *t = *f; + t++; + } + + *n = t - m; +} + +static void drop_nop(BindMount *m, unsigned *n) { + BindMount *f, *t; + + assert(m); + assert(n); + + /* Drops all entries which have an immediate parent that has the same type, as they are redundant. Assumes the + * list is ordered by prefixes. */ + + for (f = m, t = m; f < m+*n; f++) { + + /* Only suppress such subtrees for READONLY and READWRITE entries */ + if (IN_SET(f->mode, READONLY, READWRITE)) { + BindMount *p; + bool found = false; + + /* Now let's find the first parent of the entry we are looking at. */ + for (p = t-1; p >= m; p--) { + if (path_startswith(f->path, p->path)) { + found = true; + break; + } + } + + /* We found it, let's see if it's the same mode, if so, we can drop this entry */ + if (found && p->mode == f->mode) { + log_debug("%s is redundant by %s", f->path, p->path); + continue; + } + } + + *t = *f; + t++; + } + + *n = t - m; +} + +static void drop_outside_root(const char *root_directory, BindMount *m, unsigned *n) { + BindMount *f, *t; + + assert(m); + assert(n); + + if (!root_directory) + return; + + /* Drops all mounts that are outside of the root directory. */ + + for (f = m, t = m; f < m+*n; f++) { + + if (!path_startswith(f->path, root_directory)) { + log_debug("%s is outside of root directory.", f->path); + continue; + } + + *t = *f; + 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); + + log_debug("Applying namespace mount on %s", m->path); + + switch (m->mode) { + + case INACCESSIBLE: { + struct stat target; + + /* First, get rid of everything that is below if there + * is anything... Then, overmount it with an + * inaccessible path. */ + (void) umount_recursive(m->path, 0); + + if (lstat(m->path, &target) < 0) + return log_debug_errno(errno, "Failed to lstat() %s to determine what to mount over it: %m", m->path); + + what = mode_to_inaccessible_node(target.st_mode); + if (!what) { + log_debug("File type not supported for inaccessible mounts. Note that symlinks are not allowed"); + return -ELOOP; + } + break; + } + + case READONLY: + case READWRITE: + + r = path_is_mount_point(m->path, 0); + if (r < 0) + return log_debug_errno(r, "Failed to determine whether %s is already a mount point: %m", m->path); + if (r > 0) /* Nothing to do here, it is already a mount. We just later toggle the MS_RDONLY bit for the mount point if needed. */ + return 0; + + /* This isn't a mount point yet, let's make it one. */ + what = m->path; + break; + + 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); + + if (mount(what, m->path, NULL, MS_BIND|MS_REC, NULL) < 0) + return log_debug_errno(errno, "Failed to mount %s to %s: %m", what, m->path); + + log_debug("Successfully mounted %s to %s", what, m->path); + return 0; +} + +static int make_read_only(BindMount *m, char **blacklist) { + int r = 0; + + assert(m); + + if (IN_SET(m->mode, INACCESSIBLE, READONLY)) + r = bind_remount_recursive(m->path, true, blacklist); + else if (m->mode == PRIVATE_DEV) { /* Can be readonly but the submounts can't*/ + if (mount(NULL, m->path, NULL, MS_REMOUNT|DEV_MOUNT_OPTIONS|MS_RDONLY, NULL) < 0) + r = -errno; + } else + return 0; + + /* Not that we only turn on the MS_RDONLY flag here, we never turn it off. Something that was marked read-only + * already stays this way. This improves compatibility with container managers, where we won't attempt to undo + * read-only mounts already applied. */ + + return r; +} + +static int chase_all_symlinks(const char *root_directory, BindMount *m, unsigned *n) { + BindMount *f, *t; + int r; + + assert(m); + assert(n); + + /* Since mount() will always follow symlinks and we need to take the different root directory into account we + * chase the symlinks on our own first. This call wil do so for all entries and remove all entries where we + * can't resolve the path, and which have been marked for such removal. */ + + for (f = m, t = m; f < m+*n; f++) { + + r = chase_symlinks(f->path, root_directory, &f->chased); + if (r == -ENOENT && f->ignore) /* Doesn't exist? Then remove it! */ + continue; + if (r < 0) + return log_debug_errno(r, "Failed to chase symlinks for %s: %m", f->path); + + if (path_equal(f->path, f->chased)) + f->chased = mfree(f->chased); + else { + log_debug("Chased %s → %s", f->path, f->chased); + f->path = f->chased; + } + + *t = *f; + t++; + } + + *n = t - m; + return 0; +} + +static unsigned namespace_calculate_mounts( + const NameSpaceInfo *ns_info, + char** read_write_paths, + char** read_only_paths, + char** inaccessible_paths, + const char* tmp_dir, + const char* var_tmp_dir, + ProtectHome protect_home, + ProtectSystem protect_system) { + + unsigned protect_home_cnt; + unsigned protect_system_cnt = + (protect_system == PROTECT_SYSTEM_STRICT ? + ELEMENTSOF(protect_system_strict_table) : + ((protect_system == PROTECT_SYSTEM_FULL) ? + ELEMENTSOF(protect_system_full_table) : + ((protect_system == PROTECT_SYSTEM_YES) ? + ELEMENTSOF(protect_system_yes_table) : 0))); + + protect_home_cnt = + (protect_home == PROTECT_HOME_YES ? + ELEMENTSOF(protect_home_yes_table) : + ((protect_home == PROTECT_HOME_READ_ONLY) ? + ELEMENTSOF(protect_home_read_only_table) : 0)); + + return !!tmp_dir + !!var_tmp_dir + + strv_length(read_write_paths) + + strv_length(read_only_paths) + + strv_length(inaccessible_paths) + + ns_info->private_dev + + (ns_info->protect_kernel_tunables ? ELEMENTSOF(protect_kernel_tunables_table) : 0) + + (ns_info->protect_control_groups ? 1 : 0) + + (ns_info->protect_kernel_modules ? ELEMENTSOF(protect_kernel_modules_table) : 0) + + protect_home_cnt + protect_system_cnt; +} + +int setup_namespace( + const char* root_directory, + const NameSpaceInfo *ns_info, + char** read_write_paths, + char** read_only_paths, + char** inaccessible_paths, + const char* tmp_dir, + const char* var_tmp_dir, + ProtectHome protect_home, + ProtectSystem protect_system, + unsigned long mount_flags) { + + BindMount *m, *mounts = NULL; + bool make_slave = false; + unsigned n; + int r = 0; + + if (mount_flags == 0) + mount_flags = MS_SHARED; + + n = namespace_calculate_mounts(ns_info, + read_write_paths, + read_only_paths, + inaccessible_paths, + tmp_dir, var_tmp_dir, + protect_home, protect_system); + + /* Set mount slave mode */ + if (root_directory || n > 0) + make_slave = true; + + if (n > 0) { + m = mounts = (BindMount *) alloca0(n * sizeof(BindMount)); + r = append_mounts(&m, read_write_paths, READWRITE); + if (r < 0) + return r; + + r = append_mounts(&m, read_only_paths, READONLY); + if (r < 0) + return r; + + r = append_mounts(&m, inaccessible_paths, 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 (ns_info->private_dev) { + m->path = prefix_roota(root_directory, "/dev"); + m->mode = PRIVATE_DEV; + m++; + } + + if (ns_info->protect_kernel_tunables) { + r = append_protect_kernel_tunables(&m, root_directory); + if (r < 0) + return r; + } + + if (ns_info->protect_kernel_modules) { + r = append_protect_kernel_modules(&m, root_directory); + if (r < 0) + return r; + } + + if (ns_info->protect_control_groups) { + m->path = prefix_roota(root_directory, "/sys/fs/cgroup"); + m->mode = READONLY; + m++; + } + + r = append_protect_home(&m, root_directory, protect_home); + if (r < 0) + return r; + + r = append_protect_system(&m, root_directory, protect_system); + if (r < 0) + return r; + + assert(mounts + n == m); + + /* Resolve symlinks manually first, as mount() will always follow them relative to the host's + * root. Moreover we want to suppress duplicates based on the resolved paths. This of course is a bit + * racy. */ + r = chase_all_symlinks(root_directory, mounts, &n); + if (r < 0) + goto finish; + + qsort(mounts, n, sizeof(BindMount), mount_path_compare); + + drop_duplicates(mounts, &n); + drop_outside_root(root_directory, mounts, &n); + drop_inaccessible(mounts, &n); + drop_nop(mounts, &n); + } + + if (unshare(CLONE_NEWNS) < 0) { + r = -errno; + goto finish; + } + + if (make_slave) { + /* 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) { + r = -errno; + goto finish; + } + } + + if (root_directory) { + /* Turn directory into bind mount, if it isn't one yet */ + r = path_is_mount_point(root_directory, AT_SYMLINK_FOLLOW); + if (r < 0) + goto finish; + if (r == 0) { + if (mount(root_directory, root_directory, NULL, MS_BIND|MS_REC, NULL) < 0) { + r = -errno; + goto finish; + } + } + } + + if (n > 0) { + char **blacklist; + unsigned j; + + /* First round, add in all special mounts we need */ + for (m = mounts; m < mounts + n; ++m) { + r = apply_mount(m, tmp_dir, var_tmp_dir); + if (r < 0) + goto finish; + } + + /* Create a blacklist we can pass to bind_mount_recursive() */ + blacklist = newa(char*, n+1); + for (j = 0; j < n; j++) + blacklist[j] = (char*) mounts[j].path; + blacklist[j] = NULL; + + /* Second round, flip the ro bits if necessary. */ + for (m = mounts; m < mounts + n; ++m) { + r = make_read_only(m, blacklist); + if (r < 0) + goto finish; + } + } + + 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); + if (r < 0) + goto finish; + } + + /* 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) { + r = -errno; + goto finish; + } + + r = 0; + +finish: + for (m = mounts; m < mounts + n; m++) + free(m->chased); + + 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: + (void) 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", + [PROTECT_SYSTEM_STRICT] = "strict", +}; + +DEFINE_STRING_TABLE_LOOKUP(protect_system, ProtectSystem); |