Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 566 insertions, 0 deletions

diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
new file mode 100644
index 0000000..3ce6164
--- /dev/null
+++ b/src/core/mount-setup.c
@@ -0,0 +1,566 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <ftw.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/statvfs.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "bus-util.h"
+#include "cgroup-util.h"
+#include "dev-setup.h"
+#include "dirent-util.h"
+#include "efivars.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "label.h"
+#include "log.h"
+#include "macro.h"
+#include "missing.h"
+#include "mkdir.h"
+#include "mount-setup.h"
+#include "mountpoint-util.h"
+#include "path-util.h"
+#include "set.h"
+#include "smack-util.h"
+#include "strv.h"
+#include "user-util.h"
+#include "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,
+} 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[] = {
+        { "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                   },
+#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=*",  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 },
+        { "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",                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,                  },
+};
+
+/* 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, 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 (mount(p->what,
+                  p->where,
+                  p->type,
+                  p->flags,
+                  p->options) < 0) {
+                log_full_errno(priority, 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, 0);
+
+        if (p->mode & MNT_CHECK_WRITABLE) {
+                if (access(p->where, W_OK) < 0) {
+                        r = -errno;
+
+                        (void) umount(p->where);
+                        (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 = 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;
+
+                /* 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("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755");
+
+        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(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(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_closedir_ DIR *d = NULL;
+        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.
+         */
+
+        d = opendir("/run/systemd/relabel-extra.d/");
+        if (!d) {
+                if (errno == ENOENT)
+                        return 0;
+
+                return log_warning_errno(errno, "Failed to open /run/systemd/relabel-extra.d/, ignoring: %m");
+        }
+
+        for (;;) {
+                _cleanup_fclose_ FILE *f = NULL;
+                _cleanup_close_ int fd = -1;
+                struct dirent *de;
+
+                errno = 0;
+                de = readdir_no_dot(d);
+                if (!de) {
+                        if (errno != 0)
+                                return log_error_errno(errno, "Failed read directory /run/systemd/relabel-extra.d/, ignoring: %m");
+                        break;
+                }
+
+                if (hidden_or_backup_file(de->d_name))
+                        continue;
+
+                if (!endswith(de->d_name, ".relabel"))
+                        continue;
+
+                if (!IN_SET(de->d_type, DT_REG, DT_UNKNOWN))
+                        continue;
+
+                fd = openat(dirfd(d), de->d_name, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
+                if (fd < 0) {
+                        log_warning_errno(errno, "Failed to open /run/systemd/relabel-extra.d/%s, ignoring: %m", de->d_name);
+                        continue;
+                }
+
+                f = fdopen(fd, "r");
+                if (!f) {
+                        log_warning_errno(errno, "Failed to convert file descriptor into file object, ignoring: %m");
+                        continue;
+                }
+                TAKE_FD(fd);
+
+                for (;;) {
+                        _cleanup_free_ char *line = NULL;
+
+                        r = read_line(f, LONG_LINE_MAX, &line);
+                        if (r < 0) {
+                                log_warning_errno(r, "Failed to read from /run/systemd/relabel-extra.d/%s, ignoring: %m", de->d_name);
+                                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) nftw(line, nftw_cb, 64, FTW_MOUNT|FTW_PHYS|FTW_ACTIONRETVAL);
+                        c++;
+                }
+
+                if (unlinkat(dirfd(d), de->d_name, 0) < 0)
+                        log_warning_errno(errno, "Failed to remove /run/systemd/relabel-extra.d/%s, ignoring: %m", de->d_name);
+        }
+
+        /* Remove when we completing things. */
+        if (rmdir("/run/systemd/relabel-extra.d") < 0)
+                log_warning_errno(errno, "Failed to remove /run/systemd/relabel-extra.d/ directory: %m");
+
+        return c;
+}
+#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 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)
+                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);
+
+        /* Also create /run/systemd/inaccessible nodes, so that we always have something to mount inaccessible nodes
+         * from. */
+        (void) make_inaccessible_nodes(NULL, UID_INVALID, GID_INVALID);
+
+        return 0;
+}