chiark / gitweb /
nspawn: make nspawn robust to container failure
[elogind.git] / src / nspawn / nspawn.c
index d8d0dae16426828372347a022e1d0aafb5fed414..a1d77244f8c38edab93f1139cff95a3af6355f1a 100644 (file)
 #include "def.h"
 #include "rtnl-util.h"
 #include "udev-util.h"
+#include "eventfd-util.h"
 #include "blkid-util.h"
 #include "gpt.h"
+#include "siphash24.h"
 
 #ifdef HAVE_SECCOMP
 #include "seccomp-util.h"
 #endif
 
+typedef enum ContainerStatus {
+        CONTAINER_TERMINATED,
+        CONTAINER_REBOOTED
+} ContainerStatus;
+
 typedef enum LinkJournal {
         LINK_NO,
         LINK_AUTO,
@@ -656,7 +663,7 @@ static int mount_binds(const char *dest, char **l, unsigned long flags) {
                                 return r;
                         }
                 } else {
-                        log_error("Failed to bind mount %s: %s", *x, strerror(errno));
+                        log_error("Failed to bind mount %s: %m", *x);
                         return -errno;
                 }
                 /* Create the mount point, but be conservative -- refuse to create block
@@ -768,6 +775,15 @@ static int setup_resolv_conf(const char *dest) {
         return 0;
 }
 
+static char* id128_format_as_uuid(sd_id128_t id, char s[37]) {
+
+        snprintf(s, 37,
+                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+                 SD_ID128_FORMAT_VAL(id));
+
+        return s;
+}
+
 static int setup_boot_id(const char *dest) {
         _cleanup_free_ char *from = NULL, *to = NULL;
         sd_id128_t rnd = {};
@@ -793,10 +809,7 @@ static int setup_boot_id(const char *dest) {
                 return r;
         }
 
-        snprintf(as_uuid, sizeof(as_uuid),
-                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
-                 SD_ID128_FORMAT_VAL(rnd));
-        char_array_0(as_uuid);
+        id128_format_as_uuid(rnd, as_uuid);
 
         r = write_string_file(from, as_uuid);
         if (r < 0) {
@@ -879,23 +892,19 @@ static int setup_ptmx(const char *dest) {
 }
 
 static int setup_dev_console(const char *dest, const char *console) {
+        _cleanup_umask_ mode_t u;
+        const char *to;
         struct stat st;
-        _cleanup_free_ char *to = NULL;
         int r;
-        _cleanup_umask_ mode_t u;
 
         assert(dest);
         assert(console);
 
         u = umask(0000);
 
-        if (stat(console, &st) < 0) {
-                log_error("Failed to stat %s: %m", console);
+        if (stat("/dev/null", &st) < 0) {
+                log_error("Failed to stat /dev/null: %m");
                 return -errno;
-
-        } else if (!S_ISCHR(st.st_mode)) {
-                log_error("/dev/console is not a char device");
-                return -EIO;
         }
 
         r = chmod_and_chown(console, 0600, 0, 0);
@@ -904,16 +913,15 @@ static int setup_dev_console(const char *dest, const char *console) {
                 return r;
         }
 
-        if (asprintf(&to, "%s/dev/console", dest) < 0)
-                return log_oom();
-
         /* We need to bind mount the right tty to /dev/console since
          * ptys can only exist on pts file systems. To have something
-         * to bind mount things on we create a device node first, that
-         * has the right major/minor (note that the major minor
-         * doesn't actually matter here, since we mount it over
-         * anyway). */
+         * to bind mount things on we create a device node first, and
+         * use /dev/null for that since we the cgroups device policy
+         * allows us to create that freely, while we cannot create
+         * /dev/console. (Note that the major minor doesn't actually
+         * matter here, since we mount it over anyway). */
 
+        to = strappenda(dest, "/dev/console");
         if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
                 log_error("mknod() for /dev/console failed: %m");
                 return -errno;
@@ -990,7 +998,7 @@ static int setup_kmsg(const char *dest, int kmsg_socket) {
         /* Store away the fd in the socket, so that it stays open as
          * long as we run the child */
         k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
-        close_nointr_nofail(fd);
+        safe_close(fd);
 
         if (k < 0) {
                 log_error("Failed to send FIFO fd: %m");
@@ -1141,10 +1149,8 @@ static int setup_journal(const char *directory) {
         } else if (access(p, F_OK) < 0)
                 return 0;
 
-        if (dir_is_empty(q) == 0) {
-                log_error("%s not empty.", q);
-                return -ENOTEMPTY;
-        }
+        if (dir_is_empty(q) == 0)
+                log_warning("%s is not empty, proceeding anyway.", q);
 
         r = mkdir_p(q, 0755);
         if (r < 0) {
@@ -1263,7 +1269,7 @@ static int register_machine(pid_t pid) {
                         return r;
                 }
 
-                r = sd_bus_message_append(m, "(sv)", "DeviceAllow", "a(ss)", 8,
+                r = sd_bus_message_append(m, "(sv)", "DeviceAllow", "a(ss)", 10,
                                           /* Allow the container to
                                            * access and create the API
                                            * device nodes, so that
@@ -1282,7 +1288,18 @@ static int register_machine(pid_t pid) {
                                            * container to ever create
                                            * these device nodes. */
                                           "/dev/pts/ptmx", "rw",
-                                          "char-pts", "rw");
+                                          "char-pts", "rw",
+                                          /* Allow the container
+                                           * access to all kdbus
+                                           * devices. Again, the
+                                           * container cannot create
+                                           * these nodes, only use
+                                           * them. We use a pretty
+                                           * open match here, so that
+                                           * the kernel API can still
+                                           * change. */
+                                          "char-kdbus", "rw",
+                                          "char-kdbus/*", "rw");
                 if (r < 0) {
                         log_error("Failed to add device whitelist: %s", strerror(-r));
                         return r;
@@ -1393,9 +1410,46 @@ static int reset_audit_loginuid(void) {
         return 0;
 }
 
+#define HASH_KEY SD_ID128_MAKE(c3,c4,f9,19,b5,57,b2,1c,e6,cf,14,27,03,9c,ee,a2)
+
+static int get_mac(struct ether_addr *mac) {
+        int r;
+
+        uint8_t result[8];
+        size_t l, sz;
+        uint8_t *v;
+
+        l = strlen(arg_machine);
+        sz = sizeof(sd_id128_t) + l;
+        v = alloca(sz);
+
+        /* fetch some persistent data unique to the host */
+        r = sd_id128_get_machine((sd_id128_t*) v);
+        if (r < 0)
+                return r;
+
+        /* combine with some data unique (on this host) to this
+         * container instance */
+        memcpy(v + sizeof(sd_id128_t), arg_machine, l);
+
+        /* Let's hash the host machine ID plus the container name. We
+         * use a fixed, but originally randomly created hash key here. */
+        siphash24(result, v, sz, HASH_KEY.bytes);
+
+        assert_cc(ETH_ALEN <= sizeof(result));
+        memcpy(mac->ether_addr_octet, result, ETH_ALEN);
+
+        /* see eth_random_addr in the kernel */
+        mac->ether_addr_octet[0] &= 0xfe;        /* clear multicast bit */
+        mac->ether_addr_octet[0] |= 0x02;        /* set local assignment bit (IEEE802) */
+
+        return 0;
+}
+
 static int setup_veth(pid_t pid, char iface_name[IFNAMSIZ]) {
         _cleanup_rtnl_message_unref_ sd_rtnl_message *m = NULL;
         _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
+        struct ether_addr mac;
         int r;
 
         if (!arg_private_network)
@@ -1410,9 +1464,14 @@ static int setup_veth(pid_t pid, char iface_name[IFNAMSIZ]) {
                 memcpy(iface_name, "vb-", 3);
         else
                 memcpy(iface_name, "ve-", 3);
-
         strncpy(iface_name+3, arg_machine, IFNAMSIZ - 3);
 
+        r = get_mac(&mac);
+        if (r < 0) {
+                log_error("Failed to generate predictable MAC address for host0");
+                return r;
+        }
+
         r = sd_rtnl_open(&rtnl, 0);
         if (r < 0) {
                 log_error("Failed to connect to netlink: %s", strerror(-r));
@@ -1437,13 +1496,7 @@ static int setup_veth(pid_t pid, char iface_name[IFNAMSIZ]) {
                 return r;
         }
 
-        r = sd_rtnl_message_append_string(m, IFLA_INFO_KIND, "veth");
-        if (r < 0) {
-                log_error("Failed to append netlink kind: %s", strerror(-r));
-                return r;
-        }
-
-        r = sd_rtnl_message_open_container(m, IFLA_INFO_DATA);
+        r = sd_rtnl_message_open_container_union(m, IFLA_INFO_DATA, "veth");
         if (r < 0) {
                 log_error("Failed to open netlink container: %s", strerror(-r));
                 return r;
@@ -1461,6 +1514,12 @@ static int setup_veth(pid_t pid, char iface_name[IFNAMSIZ]) {
                 return r;
         }
 
+        r = sd_rtnl_message_append_ether_addr(m, IFLA_ADDRESS, &mac);
+        if (r < 0) {
+                log_error("Failed to add netlink MAC address: %s", strerror(-r));
+                return r;
+        }
+
         r = sd_rtnl_message_append_u32(m, IFLA_NET_NS_PID, pid);
         if (r < 0) {
                 log_error("Failed to add netlink namespace field: %s", strerror(-r));
@@ -1526,6 +1585,12 @@ static int setup_bridge(const char veth_name[]) {
                 return r;
         }
 
+        r = sd_rtnl_message_link_set_flags(m, IFF_UP, IFF_UP);
+        if (r < 0) {
+                log_error("Failed to set IFF_UP flag: %s", strerror(-r));
+                return r;
+        }
+
         r = sd_rtnl_message_append_string(m, IFLA_IFNAME, veth_name);
         if (r < 0) {
                 log_error("Failed to add netlink interface name field: %s", strerror(-r));
@@ -1696,13 +1761,7 @@ static int setup_macvlan(pid_t pid) {
                         return r;
                 }
 
-                r = sd_rtnl_message_append_string(m, IFLA_INFO_KIND, "macvlan");
-                if (r < 0) {
-                        log_error("Failed to append netlink kind: %s", strerror(-r));
-                        return r;
-                }
-
-                r = sd_rtnl_message_open_container(m, IFLA_INFO_DATA);
+                r = sd_rtnl_message_open_container_union(m, IFLA_INFO_DATA, "macvlan");
                 if (r < 0) {
                         log_error("Failed to open netlink container: %s", strerror(-r));
                         return r;
@@ -1885,9 +1944,9 @@ static int setup_image(char **device_path, int *loop_nr) {
 
 static int dissect_image(
                 int fd,
-                char **root_device,
-                char **home_device,
-                char **srv_device,
+                char **root_device, bool *root_device_rw,
+                char **home_device, bool *home_device_rw,
+                char **srv_device, bool *srv_device_rw,
                 bool *secondary) {
 
 #ifdef HAVE_BLKID
@@ -1898,6 +1957,7 @@ static int dissect_image(
         _cleanup_blkid_free_probe_ blkid_probe b = NULL;
         _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;
         const char *pttype = NULL;
         blkid_partlist pl;
         struct stat st;
@@ -1987,6 +2047,7 @@ static int dissect_image(
         udev_list_entry_foreach(item, first) {
                 _cleanup_udev_device_unref_ struct udev_device *q;
                 const char *stype, *node;
+                unsigned long long flags;
                 sd_id128_t type_id;
                 blkid_partition pp;
                 dev_t qn;
@@ -2017,6 +2078,10 @@ static int dissect_image(
                 if (!pp)
                         continue;
 
+                flags = blkid_partition_get_flags(pp);
+                if (flags & GPT_FLAG_NO_AUTO)
+                        continue;
+
                 nr = blkid_partition_get_partno(pp);
                 if (nr < 0)
                         continue;
@@ -2034,6 +2099,8 @@ static int dissect_image(
                                 continue;
 
                         home_nr = nr;
+                        home_rw = !(flags & GPT_FLAG_READ_ONLY);
+
                         free(home);
                         home = strdup(node);
                         if (!home)
@@ -2044,6 +2111,8 @@ static int dissect_image(
                                 continue;
 
                         srv_nr = nr;
+                        srv_rw = !(flags & GPT_FLAG_READ_ONLY);
+
                         free(srv);
                         srv = strdup(node);
                         if (!srv)
@@ -2056,6 +2125,8 @@ static int dissect_image(
                                 continue;
 
                         root_nr = nr;
+                        root_rw = !(flags & GPT_FLAG_READ_ONLY);
+
                         free(root);
                         root = strdup(node);
                         if (!root)
@@ -2069,6 +2140,9 @@ static int dissect_image(
                                 continue;
 
                         secondary_root_nr = nr;
+                        secondary_root_rw = !(flags & GPT_FLAG_READ_ONLY);
+
+
                         free(secondary_root);
                         secondary_root = strdup(node);
                         if (!secondary_root)
@@ -2086,21 +2160,29 @@ static int dissect_image(
         if (root) {
                 *root_device = root;
                 root = NULL;
+
+                *root_device_rw = root_rw;
                 *secondary = false;
         } else if (secondary_root) {
                 *root_device = secondary_root;
                 secondary_root = NULL;
+
+                *root_device_rw = secondary_root_rw;
                 *secondary = true;
         }
 
         if (home) {
                 *home_device = home;
                 home = NULL;
+
+                *home_device_rw = home_rw;
         }
 
         if (srv) {
                 *srv_device = srv;
                 srv = NULL;
+
+                *srv_device_rw = srv_rw;
         }
 
         return 0;
@@ -2110,7 +2192,7 @@ static int dissect_image(
 #endif
 }
 
-static int mount_device(const char *what, const char *where, const char *directory) {
+static int mount_device(const char *what, const char *where, const char *directory, bool rw) {
 #ifdef HAVE_BLKID
         _cleanup_blkid_free_probe_ blkid_probe b = NULL;
         const char *fstype, *p;
@@ -2119,6 +2201,9 @@ static int mount_device(const char *what, const char *where, const char *directo
         assert(what);
         assert(where);
 
+        if (arg_read_only)
+                rw = false;
+
         if (directory)
                 p = strappenda(where, directory);
         else
@@ -2161,7 +2246,7 @@ static int mount_device(const char *what, const char *where, const char *directo
                 return -ENOTSUP;
         }
 
-        if (mount(what, p, fstype, arg_read_only ? MS_NODEV|MS_RDONLY : 0, NULL) < 0) {
+        if (mount(what, p, fstype, MS_NODEV|(rw ? 0 : MS_RDONLY), NULL) < 0) {
                 log_error("Failed to mount %s: %m", what);
                 return -errno;
         }
@@ -2173,13 +2258,17 @@ static int mount_device(const char *what, const char *where, const char *directo
 #endif
 }
 
-static int mount_devices(const char *where, const char *root_device, const char *home_device, const char *srv_device) {
+static int mount_devices(
+                const char *where,
+                const char *root_device, bool root_device_rw,
+                const char *home_device, bool home_device_rw,
+                const char *srv_device, bool srv_device_rw) {
         int r;
 
         assert(where);
 
         if (root_device) {
-                r = mount_device(root_device, arg_directory, NULL);
+                r = mount_device(root_device, arg_directory, NULL, root_device_rw);
                 if (r < 0) {
                         log_error("Failed to mount root directory: %s", strerror(-r));
                         return r;
@@ -2187,7 +2276,7 @@ static int mount_devices(const char *where, const char *root_device, const char
         }
 
         if (home_device) {
-                r = mount_device(home_device, arg_directory, "/home");
+                r = mount_device(home_device, arg_directory, "/home", home_device_rw);
                 if (r < 0) {
                         log_error("Failed to mount home directory: %s", strerror(-r));
                         return r;
@@ -2195,7 +2284,7 @@ static int mount_devices(const char *where, const char *root_device, const char
         }
 
         if (srv_device) {
-                r = mount_device(srv_device, arg_directory, "/srv");
+                r = mount_device(srv_device, arg_directory, "/srv", srv_device_rw);
                 if (r < 0) {
                         log_error("Failed to mount server data directory: %s", strerror(-r));
                         return r;
@@ -2213,8 +2302,7 @@ static void loop_remove(int nr, int *image_fd) {
 
         if (image_fd && *image_fd >= 0) {
                 ioctl(*image_fd, LOOP_CLR_FD);
-                close_nointr_nofail(*image_fd);
-                *image_fd = -1;
+                *image_fd = safe_close(*image_fd);
         }
 
         control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
@@ -2224,18 +2312,352 @@ static void loop_remove(int nr, int *image_fd) {
         ioctl(control, LOOP_CTL_REMOVE, nr);
 }
 
+static int spawn_getent(const char *database, const char *key, pid_t *rpid) {
+        int pipe_fds[2];
+        pid_t pid;
+
+        assert(database);
+        assert(key);
+        assert(rpid);
+
+        if (pipe2(pipe_fds, O_CLOEXEC) < 0) {
+                log_error("Failed to allocate pipe: %m");
+                return -errno;
+        }
+
+        pid = fork();
+        if (pid < 0) {
+                log_error("Failed to fork getent child: %m");
+                return -errno;
+        } else if (pid == 0) {
+                int nullfd;
+                char *empty_env = NULL;
+
+                if (dup3(pipe_fds[1], STDOUT_FILENO, 0) < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (pipe_fds[0] > 2)
+                        safe_close(pipe_fds[0]);
+                if (pipe_fds[1] > 2)
+                        safe_close(pipe_fds[1]);
+
+                nullfd = open("/dev/null", O_RDWR);
+                if (nullfd < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (dup3(nullfd, STDIN_FILENO, 0) < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (dup3(nullfd, STDERR_FILENO, 0) < 0)
+                        _exit(EXIT_FAILURE);
+
+                if (nullfd > 2)
+                        safe_close(nullfd);
+
+                reset_all_signal_handlers();
+                close_all_fds(NULL, 0);
+
+                execle("/usr/bin/getent", "getent", database, key, NULL, &empty_env);
+                execle("/bin/getent", "getent", database, key, NULL, &empty_env);
+                _exit(EXIT_FAILURE);
+        }
+
+        pipe_fds[1] = safe_close(pipe_fds[1]);
+
+        *rpid = pid;
+
+        return pipe_fds[0];
+}
+
+static int change_uid_gid(char **_home) {
+        char line[LINE_MAX], *w, *x, *state, *u, *g, *h;
+        _cleanup_free_ uid_t *uids = NULL;
+        _cleanup_free_ char *home = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        _cleanup_close_ int fd = -1;
+        unsigned n_uids = 0;
+        size_t sz = 0, l;
+        uid_t uid;
+        gid_t gid;
+        pid_t pid;
+        int r;
+
+        assert(_home);
+
+        if (!arg_user || streq(arg_user, "root") || streq(arg_user, "0")) {
+                /* Reset everything fully to 0, just in case */
+
+                if (setgroups(0, NULL) < 0) {
+                        log_error("setgroups() failed: %m");
+                        return -errno;
+                }
+
+                if (setresgid(0, 0, 0) < 0) {
+                        log_error("setregid() failed: %m");
+                        return -errno;
+                }
+
+                if (setresuid(0, 0, 0) < 0) {
+                        log_error("setreuid() failed: %m");
+                        return -errno;
+                }
+
+                *_home = NULL;
+                return 0;
+        }
+
+        /* First, get user credentials */
+        fd = spawn_getent("passwd", arg_user, &pid);
+        if (fd < 0)
+                return fd;
+
+        f = fdopen(fd, "r");
+        if (!f)
+                return log_oom();
+        fd = -1;
+
+        if (!fgets(line, sizeof(line), f)) {
+
+                if (!ferror(f)) {
+                        log_error("Failed to resolve user %s.", arg_user);
+                        return -ESRCH;
+                }
+
+                log_error("Failed to read from getent: %m");
+                return -errno;
+        }
+
+        truncate_nl(line);
+
+        wait_for_terminate_and_warn("getent passwd", pid);
+
+        x = strchr(line, ':');
+        if (!x) {
+                log_error("/etc/passwd entry has invalid user field.");
+                return -EIO;
+        }
+
+        u = strchr(x+1, ':');
+        if (!u) {
+                log_error("/etc/passwd entry has invalid password field.");
+                return -EIO;
+        }
+
+        u++;
+        g = strchr(u, ':');
+        if (!g) {
+                log_error("/etc/passwd entry has invalid UID field.");
+                return -EIO;
+        }
+
+        *g = 0;
+        g++;
+        x = strchr(g, ':');
+        if (!x) {
+                log_error("/etc/passwd entry has invalid GID field.");
+                return -EIO;
+        }
+
+        *x = 0;
+        h = strchr(x+1, ':');
+        if (!h) {
+                log_error("/etc/passwd entry has invalid GECOS field.");
+                return -EIO;
+        }
+
+        h++;
+        x = strchr(h, ':');
+        if (!x) {
+                log_error("/etc/passwd entry has invalid home directory field.");
+                return -EIO;
+        }
+
+        *x = 0;
+
+        r = parse_uid(u, &uid);
+        if (r < 0) {
+                log_error("Failed to parse UID of user.");
+                return -EIO;
+        }
+
+        r = parse_gid(g, &gid);
+        if (r < 0) {
+                log_error("Failed to parse GID of user.");
+                return -EIO;
+        }
+
+        home = strdup(h);
+        if (!home)
+                return log_oom();
+
+        /* Second, get group memberships */
+        fd = spawn_getent("initgroups", arg_user, &pid);
+        if (fd < 0)
+                return fd;
+
+        fclose(f);
+        f = fdopen(fd, "r");
+        if (!f)
+                return log_oom();
+        fd = -1;
+
+        if (!fgets(line, sizeof(line), f)) {
+                if (!ferror(f)) {
+                        log_error("Failed to resolve user %s.", arg_user);
+                        return -ESRCH;
+                }
+
+                log_error("Failed to read from getent: %m");
+                return -errno;
+        }
+
+        truncate_nl(line);
+
+        wait_for_terminate_and_warn("getent initgroups", pid);
+
+        /* Skip over the username and subsequent separator whitespace */
+        x = line;
+        x += strcspn(x, WHITESPACE);
+        x += strspn(x, WHITESPACE);
+
+        FOREACH_WORD(w, l, x, state) {
+                char c[l+1];
+
+                memcpy(c, w, l);
+                c[l] = 0;
+
+                if (!GREEDY_REALLOC(uids, sz, n_uids+1))
+                        return log_oom();
+
+                r = parse_uid(c, &uids[n_uids++]);
+                if (r < 0) {
+                        log_error("Failed to parse group data from getent.");
+                        return -EIO;
+                }
+        }
+
+        r = mkdir_parents(home, 0775);
+        if (r < 0) {
+                log_error("Failed to make home root directory: %s", strerror(-r));
+                return r;
+        }
+
+        r = mkdir_safe(home, 0755, uid, gid);
+        if (r < 0 && r != -EEXIST) {
+                log_error("Failed to make home directory: %s", strerror(-r));
+                return r;
+        }
+
+        fchown(STDIN_FILENO, uid, gid);
+        fchown(STDOUT_FILENO, uid, gid);
+        fchown(STDERR_FILENO, uid, gid);
+
+        if (setgroups(n_uids, uids) < 0) {
+                log_error("Failed to set auxiliary groups: %m");
+                return -errno;
+        }
+
+        if (setresgid(gid, gid, gid) < 0) {
+                log_error("setregid() failed: %m");
+                return -errno;
+        }
+
+        if (setresuid(uid, uid, uid) < 0) {
+                log_error("setreuid() failed: %m");
+                return -errno;
+        }
+
+        if (_home) {
+                *_home = home;
+                home = NULL;
+        }
+
+        return 0;
+}
+
+/*
+ * Return 0 in case the container is being rebooted, has been shut
+ * down or exited successfully. On failures a negative value is
+ * returned.
+ *
+ * The status of the container "CONTAINER_TERMINATED" or
+ * "CONTAINER_REBOOTED" will be saved in the container argument
+ */
+static int wait_for_container(pid_t pid, ContainerStatus *container) {
+        int r;
+        siginfo_t status;
+
+        r = wait_for_terminate(pid, &status);
+        if (r < 0)
+                return r;
+
+        switch (status.si_code) {
+        case CLD_EXITED:
+                r = status.si_status;
+                if (r == 0) {
+                        if (!arg_quiet)
+                                log_debug("Container %s exited successfully.",
+                                          arg_machine);
+
+                        *container = CONTAINER_TERMINATED;
+                } else {
+                        log_error("Container %s failed with error code %i.",
+                                  arg_machine, status.si_status);
+                        r = -1;
+                }
+                break;
+
+        case CLD_KILLED:
+                if (status.si_status == SIGINT) {
+                        if (!arg_quiet)
+                                log_info("Container %s has been shut down.",
+                                         arg_machine);
+
+                        *container = CONTAINER_TERMINATED;
+                        r = 0;
+                        break;
+                } else if (status.si_status == SIGHUP) {
+                        if (!arg_quiet)
+                                log_info("Container %s is being rebooted.",
+                                         arg_machine);
+
+                        *container = CONTAINER_REBOOTED;
+                        r = 0;
+                        break;
+                }
+                /* CLD_KILLED fallthrough */
+
+        case CLD_DUMPED:
+                log_error("Container %s terminated by signal %s.",
+                          arg_machine, signal_to_string(status.si_status));
+                r = -1;
+                break;
+
+        default:
+                log_error("Container %s failed due to unknown reason.",
+                          arg_machine);
+                r = -1;
+                break;
+        }
+
+        return r;
+}
+
+static void nop_handler(int sig) {}
+
 int main(int argc, char *argv[]) {
 
         _cleanup_free_ char *kdbus_domain = NULL, *device_path = NULL, *root_device = NULL, *home_device = NULL, *srv_device = NULL;
-        _cleanup_close_ int master = -1, kdbus_fd = -1, sync_fd = -1, image_fd = -1;
-        _cleanup_close_pipe_ int kmsg_socket_pair[2] = { -1, -1 };
+        bool root_device_rw = true, home_device_rw = true, srv_device_rw = true;
+        _cleanup_close_ int master = -1, kdbus_fd = -1, image_fd = -1;
+        _cleanup_close_pair_ int kmsg_socket_pair[2] = { -1, -1 };
         _cleanup_fdset_free_ FDSet *fds = NULL;
         int r = EXIT_FAILURE, k, n_fd_passed, loop_nr = -1;
         const char *console = NULL;
         char veth_name[IFNAMSIZ];
         bool secondary = false;
+        sigset_t mask, mask_chld;
         pid_t pid = 0;
-        sigset_t mask;
 
         log_parse_environment();
         log_open();
@@ -2344,7 +2766,7 @@ int main(int argc, char *argv[]) {
                         goto finish;
                 }
 
-                r = dissect_image(image_fd, &root_device, &home_device, &srv_device, &secondary);
+                r = dissect_image(image_fd, &root_device, &root_device_rw, &home_device, &home_device_rw, &srv_device, &srv_device_rw, &secondary);
                 if (r < 0)
                         goto finish;
         }
@@ -2397,36 +2819,50 @@ int main(int argc, char *argv[]) {
         sd_notify(0, "READY=1");
 
         assert_se(sigemptyset(&mask) == 0);
+        assert_se(sigemptyset(&mask_chld) == 0);
+        sigaddset(&mask_chld, SIGCHLD);
         sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
         assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
 
         for (;;) {
-                siginfo_t status;
+                ContainerStatus container_status;
+                int eventfds[2] = { -1, -1 };
+                struct sigaction sa = {
+                        .sa_handler = nop_handler,
+                        .sa_flags = SA_NOCLDSTOP,
+                };
+
+                /* Child can be killed before execv(), so handle SIGCHLD
+                 * in order to interrupt parent's blocking calls and
+                 * give it a chance to call wait() and terminate. */
+                r = sigprocmask(SIG_UNBLOCK, &mask_chld, NULL);
+                if (r < 0) {
+                        log_error("Failed to change the signal mask: %m");
+                        goto finish;
+                }
 
-                sync_fd = eventfd(0, EFD_CLOEXEC);
-                if (sync_fd < 0) {
-                        log_error("Failed to create event fd: %m");
+                r = sigaction(SIGCHLD, &sa, NULL);
+                if (r < 0) {
+                        log_error("Failed to install SIGCHLD handler: %m");
                         goto finish;
                 }
 
-                pid = syscall(__NR_clone,
-                              SIGCHLD|CLONE_NEWNS|
-                              (arg_share_system ? 0 : CLONE_NEWIPC|CLONE_NEWPID|CLONE_NEWUTS)|
-                              (arg_private_network ? CLONE_NEWNET : 0), NULL);
+                pid = clone_with_eventfd(SIGCHLD|CLONE_NEWNS|
+                                         (arg_share_system ? 0 : CLONE_NEWIPC|CLONE_NEWPID|CLONE_NEWUTS)|
+                                         (arg_private_network ? CLONE_NEWNET : 0), eventfds);
                 if (pid < 0) {
                         if (errno == EINVAL)
                                 log_error("clone() failed, do you have namespace support enabled in your kernel? (You need UTS, IPC, PID and NET namespacing built in): %m");
                         else
                                 log_error("clone() failed: %m");
 
+                        r = pid;
                         goto finish;
                 }
 
                 if (pid == 0) {
                         /* child */
-                        const char *home = NULL;
-                        uid_t uid = (uid_t) -1;
-                        gid_t gid = (gid_t) -1;
+                        _cleanup_free_ char *home = NULL;
                         unsigned n_env = 2;
                         const char *envp[] = {
                                 "PATH=" DEFAULT_PATH_SPLIT_USR,
@@ -2441,21 +2877,18 @@ int main(int argc, char *argv[]) {
                                 NULL
                         };
                         char **env_use;
-                        eventfd_t x;
 
                         envp[n_env] = strv_find_prefix(environ, "TERM=");
                         if (envp[n_env])
                                 n_env ++;
 
-                        close_nointr_nofail(master);
-                        master = -1;
+                        master = safe_close(master);
 
                         close_nointr(STDIN_FILENO);
                         close_nointr(STDOUT_FILENO);
                         close_nointr(STDERR_FILENO);
 
-                        close_nointr_nofail(kmsg_socket_pair[0]);
-                        kmsg_socket_pair[0] = -1;
+                        kmsg_socket_pair[0] = safe_close(kmsg_socket_pair[0]);
 
                         reset_all_signal_handlers();
 
@@ -2465,7 +2898,7 @@ int main(int argc, char *argv[]) {
                         k = open_terminal(console, O_RDWR);
                         if (k != STDIN_FILENO) {
                                 if (k >= 0) {
-                                        close_nointr_nofail(k);
+                                        safe_close(k);
                                         k = -EINVAL;
                                 }
 
@@ -2500,7 +2933,10 @@ int main(int argc, char *argv[]) {
                                 goto child_fail;
                         }
 
-                        if (mount_devices(arg_directory, root_device, home_device, srv_device) < 0)
+                        if (mount_devices(arg_directory,
+                                          root_device, root_device_rw,
+                                          home_device, home_device_rw,
+                                          srv_device, srv_device_rw) < 0)
                                 goto child_fail;
 
                         /* Turn directory into bind mount */
@@ -2535,8 +2971,7 @@ int main(int argc, char *argv[]) {
                         if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0)
                                 goto child_fail;
 
-                        close_nointr_nofail(kmsg_socket_pair[1]);
-                        kmsg_socket_pair[1] = -1;
+                        kmsg_socket_pair[1] = safe_close(kmsg_socket_pair[1]);
 
                         if (setup_boot_id(arg_directory) < 0)
                                 goto child_fail;
@@ -2559,6 +2994,15 @@ int main(int argc, char *argv[]) {
                         if (setup_kdbus(arg_directory, kdbus_domain) < 0)
                                 goto child_fail;
 
+                        /* Tell the parent that we are ready, and that
+                         * it can cgroupify us to that we lack access
+                         * to certain devices and resources. */
+                        r = eventfd_send_state(eventfds[1],
+                                               EVENTFD_CHILD_SUCCEEDED);
+                        eventfds[1] = safe_close(eventfds[1]);
+                        if (r < 0)
+                                goto child_fail;
+
                         if (chdir(arg_directory) < 0) {
                                 log_error("chdir(%s) failed: %m", arg_directory);
                                 goto child_fail;
@@ -2589,61 +3033,9 @@ int main(int argc, char *argv[]) {
                                 goto child_fail;
                         }
 
-                        if (arg_user) {
-
-                                /* Note that this resolves user names
-                                 * inside the container, and hence
-                                 * accesses the NSS modules from the
-                                 * container and not the host. This is
-                                 * a bit weird... */
-
-                                if (get_user_creds((const char**)&arg_user, &uid, &gid, &home, NULL) < 0) {
-                                        log_error("get_user_creds() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (mkdir_parents_label(home, 0775) < 0) {
-                                        log_error("mkdir_parents_label() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (mkdir_safe_label(home, 0775, uid, gid) < 0) {
-                                        log_error("mkdir_safe_label() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (initgroups((const char*)arg_user, gid) < 0) {
-                                        log_error("initgroups() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (setresgid(gid, gid, gid) < 0) {
-                                        log_error("setregid() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (setresuid(uid, uid, uid) < 0) {
-                                        log_error("setreuid() failed: %m");
-                                        goto child_fail;
-                                }
-                        } else {
-                                /* Reset everything fully to 0, just in case */
-
-                                if (setgroups(0, NULL) < 0) {
-                                        log_error("setgroups() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (setresgid(0, 0, 0) < 0) {
-                                        log_error("setregid() failed: %m");
-                                        goto child_fail;
-                                }
-
-                                if (setresuid(0, 0, 0) < 0) {
-                                        log_error("setreuid() failed: %m");
-                                        goto child_fail;
-                                }
-                        }
+                        r = change_uid_gid(&home);
+                        if (r < 0)
+                                goto child_fail;
 
                         if ((asprintf((char**)(envp + n_env++), "HOME=%s", home ? home: "/root") < 0) ||
                             (asprintf((char**)(envp + n_env++), "USER=%s", arg_user ? arg_user : "root") < 0) ||
@@ -2653,7 +3045,9 @@ int main(int argc, char *argv[]) {
                         }
 
                         if (!sd_id128_equal(arg_uuid, SD_ID128_NULL)) {
-                                if (asprintf((char**)(envp + n_env++), "container_uuid=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(arg_uuid)) < 0) {
+                                char as_uuid[37];
+
+                                if (asprintf((char**)(envp + n_env++), "container_uuid=%s", id128_format_as_uuid(arg_uuid, as_uuid)) < 0) {
                                         log_oom();
                                         goto child_fail;
                                 }
@@ -2687,9 +3081,13 @@ int main(int argc, char *argv[]) {
                                 }
                         }
 
-                        eventfd_read(sync_fd, &x);
-                        close_nointr_nofail(sync_fd);
-                        sync_fd = -1;
+#ifdef HAVE_SELINUX
+                        if (arg_selinux_context)
+                                if (setexeccon((security_context_t) arg_selinux_context) < 0) {
+                                        log_error("setexeccon(\"%s\") failed: %m", arg_selinux_context);
+                                        goto child_fail;
+                                }
+#endif
 
                         if (!strv_isempty(arg_setenv)) {
                                 char **n;
@@ -2704,11 +3102,12 @@ int main(int argc, char *argv[]) {
                         } else
                                 env_use = (char**) envp;
 
-#ifdef HAVE_SELINUX
-                        if (arg_selinux_context)
-                                if (setexeccon((security_context_t) arg_selinux_context) < 0)
-                                        log_error("setexeccon(\"%s\") failed: %m", arg_selinux_context);
-#endif
+                        /* Wait until the parent is ready with the setup, too... */
+                        r = eventfd_parent_succeeded(eventfds[0]);
+                        eventfds[0] = safe_close(eventfds[0]);
+                        if (r < 0)
+                                goto child_fail;
+
                         if (arg_boot) {
                                 char **a;
                                 size_t l;
@@ -2738,12 +3137,28 @@ int main(int argc, char *argv[]) {
                         log_error("execv() failed: %m");
 
                 child_fail:
+                        /* Tell the parent that the setup failed, so he
+                         * can clean up resources and terminate. */
+                        if (eventfds[1] != -1)
+                                eventfd_send_state(eventfds[1],
+                                                   EVENTFD_CHILD_FAILED);
                         _exit(EXIT_FAILURE);
                 }
 
                 fdset_free(fds);
                 fds = NULL;
 
+                /* Wait for the child event:
+                 * If EVENTFD_CHILD_FAILED, the child will terminate soon.
+                 * If EVENTFD_CHILD_SUCCEEDED, the child is reporting that
+                 * it is ready with all it needs to do with priviliges.
+                 * After we got the notification we can make the process
+                 * join its cgroup which might limit what it can do */
+                r = eventfd_child_succeeded(eventfds[1]);
+                eventfds[1] = safe_close(eventfds[1]);
+                if (r < 0)
+                        goto check_container_status;
+
                 r = register_machine(pid);
                 if (r < 0)
                         goto finish;
@@ -2764,9 +3179,25 @@ int main(int argc, char *argv[]) {
                 if (r < 0)
                         goto finish;
 
-                eventfd_write(sync_fd, 1);
-                close_nointr_nofail(sync_fd);
-                sync_fd = -1;
+                /* Block SIGCHLD here, before notifying child.
+                 * process_pty() will handle it with the other signals. */
+                r = sigprocmask(SIG_BLOCK, &mask_chld, NULL);
+                if (r < 0)
+                        goto finish;
+
+                /* Reset signal to default */
+                r = default_signals(SIGCHLD, -1);
+                if (r < 0)
+                        goto finish;
+
+                /* Notify the child that the parent is ready with all
+                 * its setup, and that the child can now hand over
+                 * control to the code to run inside the container. */
+                r = eventfd_send_state(eventfds[0],
+                                       EVENTFD_PARENT_SUCCEEDED);
+                eventfds[0] = safe_close(eventfds[0]);
+                if (r < 0)
+                        goto finish;
 
                 k = process_pty(master, &mask, arg_boot ? pid : 0, SIGRTMIN+3);
                 if (k < 0) {
@@ -2780,51 +3211,20 @@ int main(int argc, char *argv[]) {
                 /* Kill if it is not dead yet anyway */
                 terminate_machine(pid);
 
+check_container_status:
                 /* Redundant, but better safe than sorry */
                 kill(pid, SIGKILL);
 
-                k = wait_for_terminate(pid, &status);
+                r = wait_for_container(pid, &container_status);
                 pid = 0;
 
-                if (k < 0) {
+                if (r < 0) {
                         r = EXIT_FAILURE;
                         break;
-                }
-
-                if (status.si_code == CLD_EXITED) {
-                        r = status.si_status;
-                        if (status.si_status != 0) {
-                                log_error("Container %s failed with error code %i.", arg_machine, status.si_status);
-                                break;
-                        }
-
-                        if (!arg_quiet)
-                                log_debug("Container %s exited successfully.", arg_machine);
-                        break;
-                } else if (status.si_code == CLD_KILLED &&
-                           status.si_status == SIGINT) {
-
-                        if (!arg_quiet)
-                                log_info("Container %s has been shut down.", arg_machine);
-                        r = 0;
+                } else if (container_status == CONTAINER_TERMINATED)
                         break;
-                } else if (status.si_code == CLD_KILLED &&
-                           status.si_status == SIGHUP) {
 
-                        if (!arg_quiet)
-                                log_info("Container %s is being rebooted.", arg_machine);
-                        continue;
-                } else if (status.si_code == CLD_KILLED ||
-                           status.si_code == CLD_DUMPED) {
-
-                        log_error("Container %s terminated by signal %s.", arg_machine, signal_to_string(status.si_status));
-                        r = EXIT_FAILURE;
-                        break;
-                } else {
-                        log_error("Container %s failed due to unknown reason.", arg_machine);
-                        r = EXIT_FAILURE;
-                        break;
-                }
+                /* CONTAINER_REBOOTED, loop again */
         }
 
 finish: