diff options
Diffstat (limited to 'src/grp-system/libcore/src/mount-setup.c')
| -rw-r--r-- | src/grp-system/libcore/src/mount-setup.c | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/src/grp-system/libcore/src/mount-setup.c b/src/grp-system/libcore/src/mount-setup.c new file mode 100644 index 0000000000..46e6f71425 --- /dev/null +++ b/src/grp-system/libcore/src/mount-setup.c @@ -0,0 +1,421 @@ +/*** + 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 <ftw.h> +#include <stdlib.h> +#include <sys/mount.h> +#include <unistd.h> + +#include "core/mount-setup.h" +#include "sd-bus/bus-util.h" +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/cgroup-util.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/label.h" +#include "systemd-basic/log.h" +#include "systemd-basic/macro.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/set.h" +#include "systemd-basic/smack-util.h" +#include "systemd-basic/strv.h" +#include "systemd-basic/user-util.h" +#include "systemd-basic/util.h" +#include "systemd-basic/virt.h" +#include "systemd-shared/dev-setup.h" +#include "systemd-shared/efivars.h" + +typedef enum MountMode { + MNT_NONE = 0, + MNT_FATAL = 1 << 0, + MNT_IN_CONTAINER = 1 << 1, +} MountMode; + +typedef struct MountPoint { + const char *what; + const char *where; + const char *type; + const char *options; + unsigned long flags; + bool (*condition_fn)(void); + MountMode mode; +} MountPoint; + +/* The first three entries we might need before SELinux is up. The + * fourth (securityfs) is needed by IMA to load a custom policy. The + * other ones we can delay until SELinux and IMA are loaded. When + * SMACK is enabled we need smackfs, too, so it's a fifth one. */ +#ifdef HAVE_SMACK +#define N_EARLY_MOUNT 5 +#else +#define N_EARLY_MOUNT 4 +#endif + +static const MountPoint mount_table[] = { + { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "devtmpfs", "/dev", "devtmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_NONE }, +#ifdef HAVE_SMACK + { "smackfs", "/sys/fs/smackfs", "smackfs", "smackfsdef=*", MS_NOSUID|MS_NOEXEC|MS_NODEV, + mac_smack_use, MNT_FATAL }, + { "tmpfs", "/dev/shm", "tmpfs", "mode=1777,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME, + mac_smack_use, MNT_FATAL }, +#endif + { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, + NULL, MNT_IN_CONTAINER }, +#ifdef HAVE_SMACK + { "tmpfs", "/run", "tmpfs", "mode=755,smackfsroot=*", MS_NOSUID|MS_NODEV|MS_STRICTATIME, + mac_smack_use, MNT_FATAL }, +#endif + { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "cgroup", "/sys/fs/cgroup", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_unified_wanted, MNT_FATAL|MNT_IN_CONTAINER }, + { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, + cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_unified_systemd_controller_wanted, MNT_IN_CONTAINER }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd,xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_legacy_systemd_controller_wanted, MNT_IN_CONTAINER }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_legacy_systemd_controller_wanted, MNT_FATAL|MNT_IN_CONTAINER }, + { "pstore", "/sys/fs/pstore", "pstore", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_NONE }, +#ifdef ENABLE_EFI + { "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + is_efi_boot, MNT_NONE }, +#endif +}; + +/* These are API file systems that might be mounted by other software, + * we just list them here so that we know that we should ignore them */ + +static const char ignore_paths[] = + /* SELinux file systems */ + "/sys/fs/selinux\0" + /* Container bind mounts */ + "/proc/sys\0" + "/dev/console\0" + "/proc/kmsg\0"; + +bool mount_point_is_api(const char *path) { + unsigned i; + + /* Checks if this mount point is considered "API", and hence + * should be ignored */ + + for (i = 0; i < ELEMENTSOF(mount_table); i ++) + if (path_equal(path, mount_table[i].where)) + return true; + + return path_startswith(path, "/sys/fs/cgroup/"); +} + +bool mount_point_ignore(const char *path) { + const char *i; + + NULSTR_FOREACH(i, ignore_paths) + if (path_equal(path, i)) + return true; + + return false; +} + +static int mount_one(const MountPoint *p, bool relabel) { + int r; + + assert(p); + + if (p->condition_fn && !p->condition_fn()) + return 0; + + /* Relabel first, just in case */ + if (relabel) + (void) label_fix(p->where, true, true); + + r = path_is_mount_point(p->where, AT_SYMLINK_FOLLOW); + if (r < 0 && r != -ENOENT) { + log_full_errno((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, r, "Failed to determine whether %s is a mount point: %m", p->where); + return (p->mode & MNT_FATAL) ? r : 0; + } + if (r > 0) + return 0; + + /* Skip securityfs in a container */ + if (!(p->mode & MNT_IN_CONTAINER) && detect_container() > 0) + return 0; + + /* The access mode here doesn't really matter too much, since + * the mounted file system will take precedence anyway. */ + if (relabel) + (void) mkdir_p_label(p->where, 0755); + else + (void) mkdir_p(p->where, 0755); + + log_debug("Mounting %s to %s of type %s with options %s.", + p->what, + p->where, + p->type, + strna(p->options)); + + if (mount(p->what, + p->where, + p->type, + p->flags, + p->options) < 0) { + log_full_errno((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, errno, "Failed to mount %s at %s: %m", p->type, p->where); + return (p->mode & MNT_FATAL) ? -errno : 0; + } + + /* Relabel again, since we now mounted something fresh here */ + if (relabel) + (void) label_fix(p->where, false, false); + + return 1; +} + +static int mount_points_setup(unsigned n, bool loaded_policy) { + unsigned i; + int r = 0; + + for (i = 0; i < n; i ++) { + int j; + + j = mount_one(mount_table + i, loaded_policy); + if (j != 0 && r >= 0) + r = j; + } + + return r; +} + +int mount_setup_early(void) { + assert_cc(N_EARLY_MOUNT <= ELEMENTSOF(mount_table)); + + /* Do a minimal mount of /proc and friends to enable the most + * basic stuff, such as SELinux */ + return mount_points_setup(N_EARLY_MOUNT, false); +} + +int mount_cgroup_controllers(char ***join_controllers) { + _cleanup_set_free_free_ Set *controllers = NULL; + int r; + + if (!cg_is_legacy_wanted()) + return 0; + + /* Mount all available cgroup controllers that are built into the kernel. */ + + controllers = set_new(&string_hash_ops); + if (!controllers) + return log_oom(); + + r = cg_kernel_controllers(controllers); + if (r < 0) + return log_error_errno(r, "Failed to enumerate cgroup controllers: %m"); + + for (;;) { + _cleanup_free_ char *options = NULL, *controller = NULL, *where = NULL; + MountPoint p = { + .what = "cgroup", + .type = "cgroup", + .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV, + .mode = MNT_IN_CONTAINER, + }; + char ***k = NULL; + + controller = set_steal_first(controllers); + if (!controller) + break; + + if (join_controllers) + for (k = join_controllers; *k; k++) + if (strv_find(*k, controller)) + break; + + if (k && *k) { + char **i, **j; + + for (i = *k, j = *k; *i; i++) { + + if (!streq(*i, controller)) { + _cleanup_free_ char *t; + + t = set_remove(controllers, *i); + if (!t) { + free(*i); + continue; + } + } + + *(j++) = *i; + } + + *j = NULL; + + options = strv_join(*k, ","); + if (!options) + return log_oom(); + } else { + options = controller; + controller = NULL; + } + + where = strappend("/sys/fs/cgroup/", options); + if (!where) + return log_oom(); + + p.where = where; + p.options = options; + + r = mount_one(&p, true); + if (r < 0) + return r; + + if (r > 0 && k && *k) { + char **i; + + for (i = *k; *i; i++) { + _cleanup_free_ char *t = NULL; + + t = strappend("/sys/fs/cgroup/", *i); + if (!t) + return log_oom(); + + r = symlink(options, t); + if (r >= 0) { +#ifdef SMACK_RUN_LABEL + _cleanup_free_ char *src; + src = strappend("/sys/fs/cgroup/", options); + if (!src) + return log_oom(); + r = mac_smack_copy(t, src); + if (r < 0 && r != -EOPNOTSUPP) + return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", src, t); +#endif + } else if (errno != EEXIST) + return log_error_errno(errno, "Failed to create symlink %s: %m", t); + } + } + } + + /* Now that we mounted everything, let's make the tmpfs the + * cgroup file systems are mounted into read-only. */ + (void) mount("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755"); + + return 0; +} + +#if defined(HAVE_SELINUX) || defined(HAVE_SMACK) +static int nftw_cb( + const char *fpath, + const struct stat *sb, + int tflag, + struct FTW *ftwbuf) { + + /* No need to label /dev twice in a row... */ + if (_unlikely_(ftwbuf->level == 0)) + return FTW_CONTINUE; + + label_fix(fpath, false, false); + + /* /run/initramfs is static data and big, no need to + * dynamically relabel its contents at boot... */ + if (_unlikely_(ftwbuf->level == 1 && + tflag == FTW_D && + streq(fpath, "/run/initramfs"))) + return FTW_SKIP_SUBTREE; + + return FTW_CONTINUE; +}; +#endif + +int mount_setup(bool loaded_policy) { + int r = 0; + + r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy); + + if (r < 0) + return r; + +#if defined(HAVE_SELINUX) || defined(HAVE_SMACK) + /* Nodes in devtmpfs and /run need to be manually updated for + * the appropriate labels, after mounting. The other virtual + * API file systems like /sys and /proc do not need that, they + * use the same label for all their files. */ + if (loaded_policy) { + usec_t before_relabel, after_relabel; + char timespan[FORMAT_TIMESPAN_MAX]; + + before_relabel = now(CLOCK_MONOTONIC); + + nftw("/dev", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + nftw("/dev/shm", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + nftw("/run", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + + after_relabel = now(CLOCK_MONOTONIC); + + log_info("Relabelled /dev and /run in %s.", + format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel, 0)); + } +#endif + + /* Create a few default symlinks, which are normally created + * by udevd, but some scripts might need them before we start + * udevd. */ + dev_setup(NULL, UID_INVALID, GID_INVALID); + + /* Mark the root directory as shared in regards to mount + * propagation. The kernel defaults to "private", but we think + * it makes more sense to have a default of "shared" so that + * nspawn and the container tools work out of the box. If + * specific setups need other settings they can reset the + * propagation mode to private if needed. */ + if (detect_container() <= 0) + if (mount(NULL, "/", NULL, MS_REC|MS_SHARED, NULL) < 0) + log_warning_errno(errno, "Failed to set up the root directory for shared mount propagation: %m"); + + /* Create a few directories we always want around, Note that + * sd_booted() checks for /run/systemd/system, so this mkdir + * really needs to stay for good, otherwise software that + * copied sd-daemon.c into their sources will misdetect + * systemd. */ + (void) mkdir_label("/run/systemd", 0755); + (void) mkdir_label("/run/systemd/system", 0755); + (void) mkdir_label("/run/systemd/inaccessible", 0000); + /* Set up inaccessible items */ + (void) mknod("/run/systemd/inaccessible/reg", S_IFREG | 0000, 0); + (void) mkdir_label("/run/systemd/inaccessible/dir", 0000); + (void) mknod("/run/systemd/inaccessible/chr", S_IFCHR | 0000, makedev(0, 0)); + (void) mknod("/run/systemd/inaccessible/blk", S_IFBLK | 0000, makedev(0, 0)); + (void) mkfifo("/run/systemd/inaccessible/fifo", 0000); + (void) mknod("/run/systemd/inaccessible/sock", S_IFSOCK | 0000, 0); + + return 0; +} |