chiark / gitweb /
nspawn: Allow module loading if CAP_SYS_MODULE is requested
[elogind.git] / src / nspawn / nspawn.c
index 588a8ae8ac8c4ff230d704eb25a7ef0342a35184..fb672510b4ff6e718a71b581d4350c48ba46d577 100644 (file)
@@ -816,6 +816,7 @@ static int mount_all(const char *dest) {
                 { "devpts",    "/dev/pts",  "devpts","newinstance,ptmxmode=0666,mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, true },
                 { "tmpfs",     "/dev/shm",  "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,      true  },
                 { "tmpfs",     "/run",      "tmpfs", "mode=755",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,      true  },
+                { "tmpfs",     "/tmp",      "tmpfs", "mode=1777", MS_STRICTATIME,                         true  },
 #ifdef HAVE_SELINUX
                 { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND,                              false },  /* Bind mount first */
                 { NULL,              "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT,         false },  /* Then, make it r/o */
@@ -913,8 +914,12 @@ static int mount_binds(const char *dest, char **l, bool ro) {
 
                 r = stat(where, &dest_st);
                 if (r == 0) {
-                        if ((source_st.st_mode & S_IFMT) != (dest_st.st_mode & S_IFMT)) {
-                                log_error("The file types of %s and %s do not match. Refusing bind mount", *x, where);
+                        if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode)) {
+                                log_error("Cannot bind mount directory %s on file %s.", *x, where);
+                                return -EINVAL;
+                        }
+                        if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode)) {
+                                log_error("Cannot bind mount file %s on directory %s.", *x, where);
                                 return -EINVAL;
                         }
                 } else if (errno == ENOENT) {
@@ -926,27 +931,18 @@ static int mount_binds(const char *dest, char **l, bool ro) {
                         return -errno;
                 }
 
-                /* Create the mount point, but be conservative -- refuse to create block
-                 * and char devices. */
+                /* Create the mount point. Any non-directory file can be
+                 * mounted on any non-directory file (regular, fifo, socket,
+                 * char, block).
+                 */
                 if (S_ISDIR(source_st.st_mode)) {
                         r = mkdir_label(where, 0755);
                         if (r < 0 && errno != EEXIST)
                                 return log_error_errno(r, "Failed to create mount point %s: %m", where);
-                } else if (S_ISFIFO(source_st.st_mode)) {
-                        r = mkfifo(where, 0644);
-                        if (r < 0 && errno != EEXIST)
-                                return log_error_errno(errno, "Failed to create mount point %s: %m", where);
-                } else if (S_ISSOCK(source_st.st_mode)) {
-                        r = mknod(where, 0644 | S_IFSOCK, 0);
-                        if (r < 0 && errno != EEXIST)
-                                return log_error_errno(errno, "Failed to create mount point %s: %m", where);
-                } else if (S_ISREG(source_st.st_mode)) {
+                } else {
                         r = touch(where);
                         if (r < 0)
                                 return log_error_errno(r, "Failed to create mount point %s: %m", where);
-                } else {
-                        log_error("Refusing to create mountpoint for file: %s", *x);
-                        return -ENOTSUP;
                 }
 
                 if (mount(*x, where, "bind", MS_BIND, NULL) < 0)
@@ -966,7 +962,7 @@ static int mount_cgroup_hierarchy(const char *dest, const char *controller, cons
         char *to;
         int r;
 
-        to = strappenda(dest, "/sys/fs/cgroup/", hierarchy);
+        to = strjoina(dest, "/sys/fs/cgroup/", hierarchy);
 
         r = path_is_mount_point(to, false);
         if (r < 0)
@@ -976,9 +972,17 @@ static int mount_cgroup_hierarchy(const char *dest, const char *controller, cons
 
         mkdir_p(to, 0755);
 
-        if (mount("cgroup", to, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV|(read_only ? MS_RDONLY : 0), controller) < 0)
+        /* The superblock mount options of the mount point need to be
+         * identical to the hosts', and hence writable... */
+        if (mount("cgroup", to, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, controller) < 0)
                 return log_error_errno(errno, "Failed to mount to %s: %m", to);
 
+        /* ... hence let's only make the bind mount read-only, not the
+         * superblock. */
+        if (read_only) {
+                if (mount(NULL, to, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
+                        return log_error_errno(errno, "Failed to remount %s read-only: %m", to);
+        }
         return 1;
 }
 
@@ -1000,7 +1004,7 @@ static int mount_cgroup(const char *dest) {
         if (r < 0)
                 return log_error_errno(r, "Failed to determine our own cgroup path: %m");
 
-        cgroup_root = strappenda(dest, "/sys/fs/cgroup");
+        cgroup_root = strjoina(dest, "/sys/fs/cgroup");
         if (mount("tmpfs", cgroup_root, "tmpfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, "mode=755") < 0)
                 return log_error_errno(errno, "Failed to mount tmpfs to /sys/fs/cgroup: %m");
 
@@ -1048,17 +1052,17 @@ static int mount_cgroup(const char *dest) {
                 }
         }
 
-        r = mount_cgroup_hierarchy(dest, "name=systemd", "systemd", false);
+        r = mount_cgroup_hierarchy(dest, "name=systemd,xattr", "systemd", false);
         if (r < 0)
                 return r;
 
         /* Make our own cgroup a (writable) bind mount */
-        systemd_own = strappenda(dest, "/sys/fs/cgroup/systemd", own_cgroup_path);
+        systemd_own = strjoina(dest, "/sys/fs/cgroup/systemd", own_cgroup_path);
         if (mount(systemd_own, systemd_own,  NULL, MS_BIND, NULL) < 0)
                 return log_error_errno(errno, "Failed to turn %s into a bind mount: %m", own_cgroup_path);
 
         /* And then remount the systemd cgroup root read-only */
-        systemd_root = strappenda(dest, "/sys/fs/cgroup/systemd");
+        systemd_root = strjoina(dest, "/sys/fs/cgroup/systemd");
         if (mount(NULL, systemd_root, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
                 return log_error_errno(errno, "Failed to mount cgroup root read-only: %m");
 
@@ -1211,7 +1215,7 @@ static int setup_volatile_state(const char *directory) {
         if (r < 0)
                 return log_error_errno(r, "Failed to remount %s read-only: %m", directory);
 
-        p = strappenda(directory, "/var");
+        p = strjoina(directory, "/var");
         r = mkdir(p, 0755);
         if (r < 0 && errno != EEXIST)
                 return log_error_errno(errno, "Failed to create %s: %m", directory);
@@ -1247,8 +1251,8 @@ static int setup_volatile(const char *directory) {
 
         tmpfs_mounted = true;
 
-        f = strappenda(directory, "/usr");
-        t = strappenda(template, "/usr");
+        f = strjoina(directory, "/usr");
+        t = strjoina(template, "/usr");
 
         r = mkdir(t, 0755);
         if (r < 0 && errno != EEXIST) {
@@ -1430,7 +1434,7 @@ static int setup_dev_console(const char *dest, const char *console) {
          * /dev/console. (Note that the major minor doesn't actually
          * matter here, since we mount it over anyway). */
 
-        to = strappenda(dest, "/dev/console");
+        to = strjoina(dest, "/dev/console");
         if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
                 return log_error_errno(errno, "mknod() for /dev/console failed: %m");
 
@@ -2481,15 +2485,18 @@ static int setup_seccomp(void) {
         static const int blacklist[] = {
                 SCMP_SYS(kexec_load),
                 SCMP_SYS(open_by_handle_at),
-                SCMP_SYS(init_module),
-                SCMP_SYS(finit_module),
-                SCMP_SYS(delete_module),
                 SCMP_SYS(iopl),
                 SCMP_SYS(ioperm),
                 SCMP_SYS(swapon),
                 SCMP_SYS(swapoff),
         };
 
+        static const int kmod_blacklist[] = {
+                SCMP_SYS(init_module),
+                SCMP_SYS(finit_module),
+                SCMP_SYS(delete_module),
+        };
+
         scmp_filter_ctx seccomp;
         unsigned i;
         int r;
@@ -2514,6 +2521,20 @@ static int setup_seccomp(void) {
                 }
         }
 
+        /* If the CAP_SYS_MODULE capability is not requested then
+         * we'll block the kmod syscalls too */
+        if (!(arg_retain & (1ULL << CAP_SYS_MODULE))) {
+                for (i = 0; i < ELEMENTSOF(kmod_blacklist); i++) {
+                        r = seccomp_rule_add(seccomp, SCMP_ACT_ERRNO(EPERM), kmod_blacklist[i], 0);
+                        if (r == -EFAULT)
+                                continue; /* unknown syscall */
+                        if (r < 0) {
+                                log_error_errno(r, "Failed to block syscall: %m");
+                                goto finish;
+                        }
+                }
+        }
+
         /*
            Audit is broken in containers, much of the userspace audit
            hookup will fail if running inside a container. We don't
@@ -2560,10 +2581,10 @@ static int setup_propagate(const char *root) {
 
         (void) mkdir_p("/run/systemd/nspawn/", 0755);
         (void) mkdir_p("/run/systemd/nspawn/propagate", 0600);
-        p = strappenda("/run/systemd/nspawn/propagate/", arg_machine);
+        p = strjoina("/run/systemd/nspawn/propagate/", arg_machine);
         (void) mkdir_p(p, 0600);
 
-        q = strappenda(root, "/run/systemd/nspawn/incoming");
+        q = strjoina(root, "/run/systemd/nspawn/incoming");
         mkdir_parents(q, 0755);
         mkdir_p(q, 0600);
 
@@ -2653,63 +2674,6 @@ static int setup_image(char **device_path, int *loop_nr) {
         return r;
 }
 
-static int wait_for_block_device(struct udev *udev, dev_t devnum, struct udev_device **ret) {
-        _cleanup_udev_monitor_unref_ struct udev_monitor *monitor = NULL;
-        int r;
-
-        assert(udev);
-        assert(ret);
-
-        for (;;) {
-                _cleanup_udev_device_unref_ struct udev_device *d = NULL;
-                struct pollfd pfd = {
-                        .events = POLLIN
-                };
-
-                d = udev_device_new_from_devnum(udev, 'b', devnum);
-                if (!d)
-                        return log_oom();
-
-                r = udev_device_get_is_initialized(d);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to check if device is initialized: %m");
-                if (r > 0) {
-                        *ret = d;
-                        d = NULL;
-                        return 0;
-                }
-                d = udev_device_unref(d);
-
-                if (!monitor) {
-                        monitor = udev_monitor_new_from_netlink(udev, "udev");
-                        if (!monitor)
-                                return log_oom();
-
-                        r = udev_monitor_filter_add_match_subsystem_devtype(monitor, "block", NULL);
-                        if (r < 0)
-                                return log_error_errno(r, "Failed to add block match: %m");
-
-                        r = udev_monitor_enable_receiving(monitor);
-                        if (r < 0)
-                                return log_error_errno(r, "Failed to turn on monitor: %m");
-
-                        continue;
-                }
-
-                pfd.fd = udev_monitor_get_fd(monitor);
-                if (pfd.fd < 0)
-                        return log_error_errno(r, "Failed to get udev monitor fd: %m");
-
-                r = poll(&pfd, 1, -1);
-                if (r < 0)
-                        return log_error_errno(errno, "Failed to wait for device initialization: %m");
-
-                d = udev_monitor_receive_device(monitor);
-        }
-
-        return 0;
-}
-
 #define PARTITION_TABLE_BLURB \
         "Note that the disk image needs to either contain only a single MBR partition of\n" \
         "type 0x83 that is marked bootable, or a sinlge GPT partition of type" \
@@ -2739,11 +2703,12 @@ static int dissect_image(
         _cleanup_udev_unref_ struct udev *udev = NULL;
         struct udev_list_entry *first, *item;
         bool home_rw = true, root_rw = true, secondary_root_rw = true, srv_rw = true, generic_rw = true;
+        bool is_gpt, is_mbr, multiple_generic = false;
         const char *pttype = NULL;
         blkid_partlist pl;
         struct stat st;
+        unsigned i;
         int r;
-        bool is_gpt, is_mbr, multiple_generic = false;
 
         assert(fd >= 0);
         assert(root_device);
@@ -2812,21 +2777,81 @@ static int dissect_image(
         if (fstat(fd, &st) < 0)
                 return log_error_errno(errno, "Failed to stat block device: %m");
 
-        r = wait_for_block_device(udev, st.st_rdev, &d);
-        if (r < 0)
-                return r;
-
-        e = udev_enumerate_new(udev);
-        if (!e)
+        d = udev_device_new_from_devnum(udev, 'b', st.st_rdev);
+        if (!d)
                 return log_oom();
 
-        r = udev_enumerate_add_match_parent(e, d);
-        if (r < 0)
-                return log_oom();
+        for (i = 0;; i++) {
+                int n, m;
 
-        r = udev_enumerate_scan_devices(e);
-        if (r < 0)
-                return log_error_errno(r, "Failed to scan for partition devices of %s: %m", arg_image);
+                if (i >= 10) {
+                        log_error("Kernel partitions never appeared.");
+                        return -ENXIO;
+                }
+
+                e = udev_enumerate_new(udev);
+                if (!e)
+                        return log_oom();
+
+                r = udev_enumerate_add_match_parent(e, d);
+                if (r < 0)
+                        return log_oom();
+
+                r = udev_enumerate_scan_devices(e);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to scan for partition devices of %s: %m", arg_image);
+
+                /* Count the partitions enumerated by the kernel */
+                n = 0;
+                first = udev_enumerate_get_list_entry(e);
+                udev_list_entry_foreach(item, first)
+                        n++;
+
+                /* Count the partitions enumerated by blkid */
+                m = blkid_partlist_numof_partitions(pl);
+                if (n == m + 1)
+                        break;
+                if (n > m + 1) {
+                        log_error("blkid and kernel partition list do not match.");
+                        return -EIO;
+                }
+                if (n < m + 1) {
+                        unsigned j;
+
+                        /* The kernel has probed fewer partitions than
+                         * blkid? Maybe the kernel prober is still
+                         * running or it got EBUSY because udev
+                         * already opened the device. Let's reprobe
+                         * the device, which is a synchronous call
+                         * that waits until probing is complete. */
+
+                        for (j = 0; j < 20; j++) {
+
+                                r = ioctl(fd, BLKRRPART, 0);
+                                if (r < 0)
+                                        r = -errno;
+                                if (r >= 0 || r != -EBUSY)
+                                        break;
+
+                                /* If something else has the device
+                                 * open, such as an udev rule, the
+                                 * ioctl will return EBUSY. Since
+                                 * there's no way to wait until it
+                                 * isn't busy anymore, let's just wait
+                                 * a bit, and try again.
+                                 *
+                                 * This is really something they
+                                 * should fix in the kernel! */
+
+                                usleep(50 * USEC_PER_MSEC);
+                        }
+
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to reread partition table: %m");
+                }
+
+                e = udev_enumerate_unref(e);
+        }
 
         first = udev_enumerate_get_list_entry(e);
         udev_list_entry_foreach(item, first) {
@@ -3042,7 +3067,7 @@ static int mount_device(const char *what, const char *where, const char *directo
                 rw = false;
 
         if (directory)
-                p = strappenda(where, directory);
+                p = strjoina(where, directory);
         else
                 p = where;
 
@@ -3602,7 +3627,6 @@ int main(int argc, char *argv[]) {
                 }
 
                 if (arg_ephemeral) {
-                        _cleanup_release_lock_file_ LockFile original_lock = LOCK_FILE_INIT;
                         char *np;
 
                         /* If the specified path is a mount point we
@@ -3678,7 +3702,7 @@ int main(int argc, char *argv[]) {
                 } else {
                         const char *p;
 
-                        p = strappenda(arg_directory,
+                        p = strjoina(arg_directory,
                                        argc > optind && path_is_absolute(argv[optind]) ? argv[optind] : "/usr/bin/");
                         if (access(p, F_OK) < 0) {
                                 log_error("Directory %s lacks the binary to execute or doesn't look like a binary tree. Refusing.", arg_directory);
@@ -4287,7 +4311,7 @@ finish:
         if (arg_machine) {
                 const char *p;
 
-                p = strappenda("/run/systemd/nspawn/propagate/", arg_machine);
+                p = strjoina("/run/systemd/nspawn/propagate/", arg_machine);
                 (void) rm_rf(p, false, true, false);
         }