From 2cb7e0aaedad73b076ea18c6900b0e86c5760d79 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 15:00:47 +0200 Subject: Adding upstream version 247.3. Signed-off-by: Daniel Baumann --- src/core/mount-setup.c | 561 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 561 insertions(+) create mode 100644 src/core/mount-setup.c (limited to 'src/core/mount-setup.c') diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c new file mode 100644 index 0000000..915b101 --- /dev/null +++ b/src/core/mount-setup.c @@ -0,0 +1,561 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include +#include +#include +#include +#include +#include + +#include "alloc-util.h" +#include "bus-util.h" +#include "cgroup-util.h" +#include "conf-files.h" +#include "cgroup-setup.h" +#include "dev-setup.h" +#include "dirent-util.h" +#include "efi-loader.h" +#include "fd-util.h" +#include "fileio.h" +#include "fs-util.h" +#include "label.h" +#include "log.h" +#include "macro.h" +#include "mkdir.h" +#include "mount-setup.h" +#include "mount-util.h" +#include "mountpoint-util.h" +#include "nulstr-util.h" +#include "path-util.h" +#include "set.h" +#include "smack-util.h" +#include "strv.h" +#include "user-util.h" +#include "virt.h" + +typedef enum MountMode { + MNT_NONE = 0, + MNT_FATAL = 1 << 0, + MNT_IN_CONTAINER = 1 << 1, + MNT_CHECK_WRITABLE = 1 << 2, + MNT_FOLLOW_SYMLINK = 1 << 3, +} 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. */ +#if ENABLE_SMACK +#define N_EARLY_MOUNT 5 +#else +#define N_EARLY_MOUNT 4 +#endif + +static const MountPoint mount_table[] = { + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_FATAL|MNT_IN_CONTAINER|MNT_FOLLOW_SYMLINK }, + { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "devtmpfs", "/dev", "devtmpfs", "mode=755" TMPFS_LIMITS_DEV, MS_NOSUID|MS_NOEXEC|MS_STRICTATIME, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "securityfs", "/sys/kernel/security", "securityfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_NONE }, +#if ENABLE_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 }, +#if ENABLE_SMACK + { "tmpfs", "/run", "tmpfs", "mode=755,smackfsroot=*" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME, + mac_smack_use, MNT_FATAL }, +#endif + { "tmpfs", "/run", "tmpfs", "mode=755" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME, + NULL, MNT_FATAL|MNT_IN_CONTAINER }, + { "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate,memory_recursiveprot", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, + { "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, + { "cgroup2", "/sys/fs/cgroup", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_unified_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, + { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755" TMPFS_LIMITS_SYS_FS_CGROUP, MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, + cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, + { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", "nsdelegate", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_hybrid_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, + { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_hybrid_wanted, MNT_IN_CONTAINER|MNT_CHECK_WRITABLE }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd,xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_legacy_wanted, MNT_IN_CONTAINER }, + { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, + cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER }, + { "pstore", "/sys/fs/pstore", "pstore", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_NONE }, +#if ENABLE_EFI + { "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, + is_efi_boot, MNT_NONE }, +#endif + { "bpf", "/sys/fs/bpf", "bpf", "mode=700", MS_NOSUID|MS_NOEXEC|MS_NODEV, + NULL, MNT_NONE, }, +}; + +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; + + /* 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. */ + FOREACH_STRING(i, + /* SELinux file systems */ + "/sys/fs/selinux", + /* Container bind mounts */ + "/dev/console", + "/proc/kmsg", + "/proc/sys", + "/proc/sys/kernel/random/boot_id") + if (path_equal(path, i)) + return true; + + if (path_startswith(path, "/run/host")) /* All mounts passed in from the container manager are + * something we better ignore. */ + return true; + + return false; +} + +static int mount_one(const MountPoint *p, bool relabel) { + int r, priority; + + assert(p); + + priority = (p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG; + + if (p->condition_fn && !p->condition_fn()) + return 0; + + /* Relabel first, just in case */ + if (relabel) + (void) label_fix(p->where, LABEL_IGNORE_ENOENT|LABEL_IGNORE_EROFS); + + r = path_is_mount_point(p->where, NULL, AT_SYMLINK_FOLLOW); + if (r < 0 && r != -ENOENT) { + log_full_errno(priority, 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 (FLAGS_SET(p->mode, MNT_FOLLOW_SYMLINK)) + r = mount(p->what, p->where, p->type, p->flags, p->options) < 0 ? -errno : 0; + else + r = mount_nofollow(p->what, p->where, p->type, p->flags, p->options); + if (r < 0) { + log_full_errno(priority, r, "Failed to mount %s at %s: %m", p->type, p->where); + return (p->mode & MNT_FATAL) ? r : 0; + } + + /* Relabel again, since we now mounted something fresh here */ + if (relabel) + (void) label_fix(p->where, 0); + + if (p->mode & MNT_CHECK_WRITABLE) { + if (access(p->where, W_OK) < 0) { + r = -errno; + + (void) umount2(p->where, UMOUNT_NOFOLLOW); + (void) rmdir(p->where); + + log_full_errno(priority, r, "Mount point %s not writable after mounting: %m", p->where); + return (p->mode & MNT_FATAL) ? r : 0; + } + } + + 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); +} + +static const char *join_with(const char *controller) { + + static const char* const pairs[] = { + "cpu", "cpuacct", + "net_cls", "net_prio", + NULL + }; + + const char *const *x, *const *y; + + assert(controller); + + /* This will lookup which controller to mount another controller with. Input is a controller name, and output + * is the other controller name. The function works both ways: you can input one and get the other, and input + * the other to get the one. */ + + STRV_FOREACH_PAIR(x, y, pairs) { + if (streq(controller, *x)) + return *y; + if (streq(controller, *y)) + return *x; + } + + return NULL; +} + +static int symlink_controller(const char *target, const char *alias) { + const char *a; + int r; + + assert(target); + assert(alias); + + a = strjoina("/sys/fs/cgroup/", alias); + + r = symlink_idempotent(target, a, false); + if (r < 0) + return log_error_errno(r, "Failed to create symlink %s: %m", a); + +#ifdef SMACK_RUN_LABEL + const char *p; + + p = strjoina("/sys/fs/cgroup/", target); + + r = mac_smack_copy(a, p); + if (r < 0 && r != -EOPNOTSUPP) + return log_error_errno(r, "Failed to copy smack label from %s to %s: %m", p, a); +#endif + + return 0; +} + +int mount_cgroup_controllers(void) { + _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. */ + 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; + const char *other_controller; + MountPoint p = { + .what = "cgroup", + .type = "cgroup", + .flags = MS_NOSUID|MS_NOEXEC|MS_NODEV, + .mode = MNT_IN_CONTAINER, + }; + + controller = set_steal_first(controllers); + if (!controller) + break; + + /* Check if we shall mount this together with another controller */ + other_controller = join_with(controller); + if (other_controller) { + _cleanup_free_ char *c = NULL; + + /* Check if the other controller is actually available in the kernel too */ + c = set_remove(controllers, other_controller); + if (c) { + + /* Join the two controllers into one string, and maintain a stable ordering */ + if (strcmp(controller, other_controller) < 0) + options = strjoin(controller, ",", other_controller); + else + options = strjoin(other_controller, ",", controller); + if (!options) + return log_oom(); + } + } + + /* The simple case, where there's only one controller to mount together */ + if (!options) + options = TAKE_PTR(controller); + + where = path_join("/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; + + /* Create symlinks from the individual controller names, in case we have a joined mount */ + if (controller) + (void) symlink_controller(options, controller); + if (other_controller) + (void) symlink_controller(options, other_controller); + } + + /* Now that we mounted everything, let's make the tmpfs the cgroup file systems are mounted into read-only. */ + (void) mount_nofollow("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755" TMPFS_LIMITS_SYS_FS_CGROUP); + + return 0; +} + +#if HAVE_SELINUX || ENABLE_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; + + (void) label_fix(fpath, 0); + + /* /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; +}; + +static int relabel_cgroup_filesystems(void) { + int r; + struct statfs st; + + r = cg_all_unified(); + if (r == 0) { + /* Temporarily remount the root cgroup filesystem to give it a proper label. Do this + only when the filesystem has been already populated by a previous instance of systemd + running from initrd. Otherwise don't remount anything and leave the filesystem read-write + for the cgroup filesystems to be mounted inside. */ + if (statfs("/sys/fs/cgroup", &st) < 0) + return log_error_errno(errno, "Failed to determine mount flags for /sys/fs/cgroup: %m"); + + if (st.f_flags & ST_RDONLY) + (void) mount_nofollow(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT, NULL); + + (void) label_fix("/sys/fs/cgroup", 0); + (void) nftw("/sys/fs/cgroup", nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + + if (st.f_flags & ST_RDONLY) + (void) mount_nofollow(NULL, "/sys/fs/cgroup", NULL, MS_REMOUNT|MS_RDONLY, NULL); + + } else if (r < 0) + return log_error_errno(r, "Failed to determine whether we are in all unified mode: %m"); + + return 0; +} + +static int relabel_extra(void) { + _cleanup_strv_free_ char **files = NULL; + char **file; + int r, c = 0; + + /* Support for relabelling additional files or directories after loading the policy. For this, code in the + * initrd simply has to drop in *.relabel files into /run/systemd/relabel-extra.d/. We'll read all such files + * expecting one absolute path by line and will relabel each (and everyone below that in case the path refers + * to a directory). These drop-in files are supposed to be absolutely minimal, and do not understand comments + * and such. After the operation succeeded the files are removed, and the drop-in directory as well, if + * possible. + */ + + r = conf_files_list(&files, ".relabel", NULL, + CONF_FILES_FILTER_MASKED | CONF_FILES_REGULAR, + "/run/systemd/relabel-extra.d/"); + if (r < 0) + return log_error_errno(r, "Failed to enumerate /run/systemd/relabel-extra.d/, ignoring: %m"); + + STRV_FOREACH(file, files) { + _cleanup_fclose_ FILE *f = NULL; + + f = fopen(*file, "re"); + if (!f) { + log_warning_errno(errno, "Failed to open %s, ignoring: %m", *file); + continue; + } + + for (;;) { + _cleanup_free_ char *line = NULL; + + r = read_line(f, LONG_LINE_MAX, &line); + if (r < 0) { + log_warning_errno(r, "Failed to read %s, ignoring: %m", *file); + break; + } + if (r == 0) /* EOF */ + break; + + path_simplify(line, true); + + if (!path_is_normalized(line)) { + log_warning("Path to relabel is not normalized, ignoring: %s", line); + continue; + } + + if (!path_is_absolute(line)) { + log_warning("Path to relabel is not absolute, ignoring: %s", line); + continue; + } + + log_debug("Relabelling additional file/directory '%s'.", line); + (void) label_fix(line, 0); + (void) nftw(line, nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + c++; + } + + if (unlink(*file) < 0) + log_warning_errno(errno, "Failed to remove %s, ignoring: %m", *file); + } + + /* Remove when we complete things. */ + if (rmdir("/run/systemd/relabel-extra.d") < 0 && + errno != ENOENT) + log_warning_errno(errno, "Failed to remove /run/systemd/relabel-extra.d/ directory: %m"); + + return c; +} +#endif + +int mount_setup(bool loaded_policy, bool leave_propagation) { + int r; + + r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy); + if (r < 0) + return r; + +#if HAVE_SELINUX || ENABLE_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]; + const char *i; + int n_extra; + + before_relabel = now(CLOCK_MONOTONIC); + + FOREACH_STRING(i, "/dev", "/dev/shm", "/run") + (void) nftw(i, nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL); + + (void) relabel_cgroup_filesystems(); + + n_extra = relabel_extra(); + + after_relabel = now(CLOCK_MONOTONIC); + + log_info("Relabelled /dev, /dev/shm, /run, /sys/fs/cgroup%s in %s.", + n_extra > 0 ? ", additional files" : "", + 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. Note that we set this only when we are invoked directly by the kernel. If we are invoked by a + * container manager we assume the container manager knows what it is doing (for example, because it set up + * some directories with different propagation modes). */ + if (detect_container() <= 0 && !leave_propagation) + 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); + + /* Make sure we have a mount point to hide in sandboxes */ + (void) mkdir_label("/run/credentials", 0755); + + /* Also create /run/systemd/inaccessible nodes, so that we always have something to mount + * inaccessible nodes from. If we run in a container the host might have created these for us already + * in /run/host/inaccessible/. Use those if we can, since that way we likely get access to block/char + * device nodes that are inaccessible, and if userns is used to nodes that are on mounts owned by a + * userns outside the container and thus nicely read-only and not remountable. */ + if (access("/run/host/inaccessible/", F_OK) < 0) { + if (errno != ENOENT) + log_debug_errno(errno, "Failed to check if /run/host/inaccessible exists, ignoring: %m"); + + (void) make_inaccessible_nodes("/run/systemd", UID_INVALID, GID_INVALID); + } else + (void) symlink("../host/inaccessible", "/run/systemd/inaccessible"); + + return 0; +} -- cgit v1.2.3