chiark / gitweb /
core: add comment why we don't bother with MS_SHARED remounting of / in containers
[elogind.git] / src / core / mount-setup.c
index c26dedca60a466b5fc24f0bff5440565ba6c42d2..f38f1ee8e72c6ffd0800c1536bb94b5963b84931 100644 (file)
@@ -1,5 +1,3 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
 /***
   This file is part of systemd.
 
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include <sys/mount.h>
 #include <errno.h>
-#include <sys/stat.h>
+#include <ftw.h>
 #include <stdlib.h>
-#include <string.h>
-#include <libgen.h>
-#include <assert.h>
+#include <sys/mount.h>
 #include <unistd.h>
-#include <ftw.h>
 
-#include "mount-setup.h"
-#include "dev-setup.h"
-#include "log.h"
-#include "macro.h"
-#include "util.h"
+#include "alloc-util.h"
+//#include "bus-util.h"
+#include "cgroup-util.h"
+//#include "dev-setup.h"
+//#include "efivars.h"
+#include "fs-util.h"
 #include "label.h"
-#include "set.h"
-#include "strv.h"
+//#include "log.h"
+#include "macro.h"
+//#include "missing.h"
 #include "mkdir.h"
+#include "mount-setup.h"
+#include "mount-util.h"
 #include "path-util.h"
-
-#ifndef TTY_GID
-#define TTY_GID 5
-#endif
+//#include "set.h"
+//#include "smack-util.h"
+//#include "strv.h"
+#include "user-util.h"
+//#include "util.h"
+#include "virt.h"
+
+/// Additional includes needed by elogind
+#include "string-util.h"
+
+typedef enum MountMode {
+        MNT_NONE  =        0,
+        MNT_FATAL =        1 <<  0,
+        MNT_IN_CONTAINER = 1 <<  1,
+} MountMode;
 
 typedef struct MountPoint {
         const char *what;
@@ -50,45 +59,85 @@ typedef struct MountPoint {
         const char *type;
         const char *options;
         unsigned long flags;
-        bool fatal;
+        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. */
+ * 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[] = {
-        { "proc",     "/proc",                  "proc",     NULL,                MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
-        { "sysfs",    "/sys",                   "sysfs",    NULL,                MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
-        { "devtmpfs", "/dev",                   "devtmpfs", "mode=755",          MS_NOSUID|MS_STRICTATIME,     true },
-        { "securityfs", "/sys/kernel/security", "securityfs", NULL,              MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
-        { "tmpfs",    "/dev/shm",               "tmpfs",    "mode=1777",         MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
-        { "devpts",   "/dev/pts",               "devpts",   "mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, false },
-        { "tmpfs",    "/run",                   "tmpfs",    "mode=755",          MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
-        { "tmpfs",    "/sys/fs/cgroup",         "tmpfs",    "mode=755",          MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, false },
-        { "cgroup",   "/sys/fs/cgroup/systemd", "cgroup",   "none,name=systemd", MS_NOSUID|MS_NOEXEC|MS_NODEV, false },
+#if 0 /// UNNEEDED by elogind
+        { "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 },
+#endif // 0
+        { "tmpfs",       "/sys/fs/cgroup",            "tmpfs",      "mode=755",                MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME,
+          cg_is_legacy_wanted, MNT_FATAL|MNT_IN_CONTAINER },
+#if 0 /// UNNEEDED by elogind
+        { "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_IN_CONTAINER  },
+#else
+        { "cgroup",      "/sys/fs/cgroup/elogind",    "cgroup",     "none,name=elogind,xattr", MS_NOSUID|MS_NOEXEC|MS_NODEV,
+          cg_is_legacy_systemd_controller_wanted, MNT_IN_CONTAINER  },
+        { "cgroup",      "/sys/fs/cgroup/elogind",    "cgroup",     "none,name=elogind",       MS_NOSUID|MS_NOEXEC|MS_NODEV,
+          cg_is_legacy_systemd_controller_wanted, MNT_IN_CONTAINER  },
+#endif // 0
+#if 0 /// UNNEEDED by elogind
+        { "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
+#endif // 0
 };
 
+#if 0 /// UNNEEDED by elogind
 /* 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"
-        "/selinux\0"
-        /* Legacy cgroup mount points */
-        "/dev/cgroup\0"
-        "/cgroup\0"
-        /* Legacy kernel file system */
-        "/proc/bus/usb\0"
         /* Container bind mounts */
         "/proc/sys\0"
         "/dev/console\0"
-        "/proc/kmsg\0"
-        "/etc/localtime\0"
-        "/etc/timezone\0"
-        "/etc/machine-id\0";
+        "/proc/kmsg\0";
 
 bool mount_point_is_api(const char *path) {
         unsigned i;
@@ -112,25 +161,38 @@ bool mount_point_ignore(const char *path) {
 
         return false;
 }
+#endif // 0
 
 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)
-                label_fix(p->where, true);
-
-        if ((r = path_is_mount_point(p->where, true)) < 0)
-                return r;
+                (void) label_fix(p->where, true, true);
 
+        r = path_is_mount_point(p->where, NULL, 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. */
-        mkdir_p_label(p->where, 0755);
+        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,
@@ -143,90 +205,66 @@ static int mount_one(const MountPoint *p, bool relabel) {
                   p->type,
                   p->flags,
                   p->options) < 0) {
-                log_full(p->fatal ? LOG_ERR : LOG_DEBUG, "Failed to mount %s: %s", p->where, strerror(errno));
-                return p->fatal ? -errno : 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)
-                label_fix(p->where, false);
+                (void) label_fix(p->where, false, false);
 
         return 1;
 }
 
-int mount_setup_early(void) {
+static int mount_points_setup(unsigned n, bool loaded_policy) {
         unsigned i;
         int r = 0;
 
-        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 */
-        for (i = 0; i < N_EARLY_MOUNT; i ++)  {
+        for (i = 0; i < n; i ++) {
                 int j;
 
-                j = mount_one(mount_table + i, false);
-                if (r == 0)
+                j = mount_one(mount_table + i, loaded_policy);
+                if (j != 0 && r >= 0)
                         r = j;
         }
 
         return r;
 }
 
+#if 0 /// UNNEEDED by elogind
+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;
-        FILE *f;
-        char buf[LINE_MAX];
-        Set *controllers;
 
-        /* Mount all available cgroup controllers that are built into the kernel. */
-
-        f = fopen("/proc/cgroups", "re");
-        if (!f) {
-                log_error("Failed to enumerate cgroup controllers: %m");
+        if (!cg_is_legacy_wanted())
                 return 0;
-        }
-
-        controllers = set_new(string_hash_func, string_compare_func);
-        if (!controllers) {
-                r = -ENOMEM;
-                log_error("Failed to allocate controller set.");
-                goto finish;
-        }
 
-        /* Ignore the header line */
-        (void) fgets(buf, sizeof(buf), f);
-
-        for (;;) {
-                char *controller;
-                int enabled = 0;
-
-                if (fscanf(f, "%ms %*i %*i %i", &controller, &enabled) != 2) {
-
-                        if (feof(f))
-                                break;
-
-                        log_error("Failed to parse /proc/cgroups.");
-                        r = -EIO;
-                        goto finish;
-                }
+        /* Mount all available cgroup controllers that are built into the kernel. */
 
-                if (!enabled) {
-                        free(controller);
-                        continue;
-                }
+        controllers = set_new(&string_hash_ops);
+        if (!controllers)
+                return log_oom();
 
-                r = set_put(controllers, controller);
-                if (r < 0) {
-                        log_error("Failed to add controller to set.");
-                        free(controller);
-                        goto finish;
-                }
-        }
+        r = cg_kernel_controllers(controllers);
+        if (r < 0)
+                return log_error_errno(r, "Failed to enumerate cgroup controllers: %m");
 
         for (;;) {
-                MountPoint p;
-                char *controller, *where, *options;
+                _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);
@@ -244,14 +282,13 @@ int mount_cgroup_controllers(char ***join_controllers) {
                         for (i = *k, j = *k; *i; i++) {
 
                                 if (!streq(*i, controller)) {
-                                        char *t;
+                                        _cleanup_free_ char *t;
 
                                         t = set_remove(controllers, *i);
                                         if (!t) {
                                                 free(*i);
                                                 continue;
                                         }
-                                        free(t);
                                 }
 
                                 *(j++) = *i;
@@ -260,82 +297,59 @@ int mount_cgroup_controllers(char ***join_controllers) {
                         *j = NULL;
 
                         options = strv_join(*k, ",");
-                        if (!options) {
-                                log_error("Failed to join options");
-                                free(controller);
-                                r = -ENOMEM;
-                                goto finish;
-                        }
-
+                        if (!options)
+                                return log_oom();
                 } else {
                         options = controller;
                         controller = NULL;
                 }
 
                 where = strappend("/sys/fs/cgroup/", options);
-                if (!where) {
-                        log_error("Failed to build path");
-                        free(options);
-                        r = -ENOMEM;
-                        goto finish;
-                }
+                if (!where)
+                        return log_oom();
 
-                zero(p);
-                p.what = "cgroup";
                 p.where = where;
-                p.type = "cgroup";
                 p.options = options;
-                p.flags = MS_NOSUID|MS_NOEXEC|MS_NODEV;
-                p.fatal = false;
 
                 r = mount_one(&p, true);
-                free(controller);
-                free(where);
-
-                if (r < 0) {
-                        free(options);
-                        goto finish;
-                }
+                if (r < 0)
+                        return r;
 
                 if (r > 0 && k && *k) {
                         char **i;
 
                         for (i = *k; *i; i++) {
-                                char *t;
+                                _cleanup_free_ char *t = NULL;
 
                                 t = strappend("/sys/fs/cgroup/", *i);
-                                if (!t) {
-                                        log_error("Failed to build path");
-                                        r = -ENOMEM;
-                                        free(options);
-                                        goto finish;
-                                }
+                                if (!t)
+                                        return log_oom();
 
                                 r = symlink(options, t);
-                                free(t);
-
-                                if (r < 0 && errno != EEXIST) {
-                                        log_error("Failed to create symlink: %m");
-                                        r = -errno;
-                                        free(options);
-                                        goto finish;
-                                }
+                                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);
                         }
                 }
-
-                free(options);
         }
 
-        r = 0;
-
-finish:
-        set_free_free(controllers);
+        /* 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");
 
-        fclose(f);
-
-        return r;
+        return 0;
 }
 
+#if defined(HAVE_SELINUX) || defined(HAVE_SMACK)
 static int nftw_cb(
                 const char *fpath,
                 const struct stat *sb,
@@ -346,7 +360,7 @@ static int nftw_cb(
         if (_unlikely_(ftwbuf->level == 0))
                 return FTW_CONTINUE;
 
-        label_fix(fpath, true);
+        label_fix(fpath, false, false);
 
         /* /run/initramfs is static data and big, no need to
          * dynamically relabel its contents at boot... */
@@ -357,24 +371,18 @@ static int nftw_cb(
 
         return FTW_CONTINUE;
 };
+#endif
+#endif // 0
 
 int mount_setup(bool loaded_policy) {
+        int r = 0;
 
-        static const char relabel[] =
-                "/run/initramfs/root-fsck\0"
-                "/run/initramfs/shutdown\0";
-
-        int r;
-        unsigned i;
-        const char *j;
-
-        for (i = 0; i < ELEMENTSOF(mount_table); i ++) {
-                r = mount_one(mount_table + i, true);
-
-                if (r < 0)
-                        return r;
-        }
+        r = mount_points_setup(ELEMENTSOF(mount_table), loaded_policy);
+        if (r < 0)
+                return r;
 
+#if 0 /// elogind does not control /, /dev, /run and /run/systemd/* are setup elsewhere.
+#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
@@ -386,26 +394,46 @@ int mount_setup(bool loaded_policy) {
                 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);
 
-                /* Explicitly relabel these */
-                NULSTR_FOREACH(j, relabel)
-                        label_fix(j, true);
-
                 after_relabel = now(CLOCK_MONOTONIC);
 
                 log_info("Relabelled /dev and /run in %s.",
-                         format_timespan(timespan, sizeof(timespan), after_relabel - before_relabel));
+                         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();
-
-        /* Create a few directories we always want around */
-        mkdir_label("/run/systemd", 0755);
-        mkdir_label("/run/systemd/system", 0755);
+        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");
+
+#endif // 0
+        /* 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);
+
+        /* Set up inaccessible items */
+        (void) mkdir_label("/run/systemd/inaccessible", 0000);
+        (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;
 }