NEWS: add blurb about os-release and $container_host_*

Container Interface: expose the host's os-release metadata to nspawn and portable guests

NEWS

@@ -516,6 +516,14 @@ CHANGES WITH 246:
 
               https://systemd.io/JOURNAL_FILE_FORMAT
 
+        * The interface for containers (https://systemd.io/CONTAINER_INTERFACE)
+          has been extended by a set of environment variables that expose
+          select fields from the host's os-release file to the container
+          payload. Similarly, host's os-release files can be mounted into the
+          container underneath /run/hosts. Together, those mechanisms provide a
+          standardized way to expose information about the host to the
+          container payload. Both interfaces are implemented in systemd-nspawn.
+
         * All D-Bus services shipped in systemd now implement the generic
           LogControl1 D-Bus API which allows clients to change log level +
           target of the service during runtime.

docs/CONTAINER_INTERFACE.md

@@ -121,6 +121,16 @@ manager, please consider supporting the following interfaces.
    `container_ttys=pts/7 pts/8 pts/14` it will spawn three additional login
    gettys on ptys 7, 8, and 14.
 
+4. To allow applications to detect the OS version and other metadata of the host
+   running the container manager, if this is considered desirable, please parse
+   the host's `/etc/os-release` and set a `$container_host_<key>=<VALUE>`
+   environment variable for the ID fields described by the [os-release
+   interface](https://www.freedesktop.org/software/systemd/man/os-release.html), eg:
+   `$container_host_id=debian`
+   `$container_host_build_id=2020-06-15`
+   `$container_host_variant_id=server`
+   `$container_host_version_id=10`
+
 ## Advanced Integration
 
 1. Consider syncing `/etc/localtime` from the host file system into the

man/os-release.xml

@@ -339,6 +339,13 @@
     name in order to avoid name clashes. Applications
     reading this file must ignore unknown fields. Example:
     <literal>DEBIAN_BTS="debbugs://bugs.debian.org/"</literal></para>
+
+    <para>Container and sandbox runtime managers may make the host's
+    identification data available to applications by providing the host's
+    <filename>/etc/os-release</filename> and
+    <filename>/usr/lib/os-release</filename> as respectively
+    <filename>/run/host/etc/os-release</filename> and
+    <filename>/run/host/usr/lib/os-release</filename>.</para>
   </refsect1>
 
   <refsect1>

man/systemd.netdev.xml

@@ -499,11 +499,22 @@
           <para>The MACVLAN mode to use. The supported options are
           <literal>private</literal>,
           <literal>vepa</literal>,
-          <literal>bridge</literal>, and
+          <literal>bridge</literal>,
-          <literal>passthru</literal>.
+          <literal>passthru</literal>, and
+          <literal>source</literal>.
           </para>
         </listitem>
       </varlistentry>
+      <varlistentry>
+        <term><varname>SourceMACAddress=</varname></term>
+        <listitem>
+          <para>A whitespace-separated list of remote hardware addresses allowed on the MACVLAN. This
+          option only has an effect in source mode. Use full colon-, hyphen- or dot-delimited
+          hexadecimal. This option may appear more than once, in which case the lists are merged. If
+          the empty string is assigned to this option, the list of hardware addresses defined prior
+          to this is reset. Defaults to unset.</para>
+        </listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 

src/basic/mkdir-label.c

@@ -10,6 +10,7 @@
 #include "mkdir.h"
 #include "selinux-util.h"
 #include "smack-util.h"
+#include "user-util.h"
 
 int mkdir_label(const char *path, mode_t mode) {
         int r;
@@ -50,9 +51,9 @@ int mkdir_safe_label(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirF
 }
 
 int mkdir_parents_label(const char *path, mode_t mode) {
-        return mkdir_parents_internal(NULL, path, mode, mkdir_label);
+        return mkdir_parents_internal(NULL, path, mode, UID_INVALID, UID_INVALID, 0, mkdir_label);
 }
 
 int mkdir_p_label(const char *path, mode_t mode) {
-        return mkdir_p_internal(NULL, path, mode, mkdir_label);
+        return mkdir_p_internal(NULL, path, mode, UID_INVALID, UID_INVALID, 0, mkdir_label);
 }

src/basic/mkdir.c

@@ -93,7 +93,7 @@ int mkdir_safe(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags f
         return mkdir_safe_internal(path, mode, uid, gid, flags, mkdir_errno_wrapper);
 }
 
-int mkdir_parents_internal(const char *prefix, const char *path, mode_t mode, mkdir_func_t _mkdir) {
+int mkdir_parents_internal(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags, mkdir_func_t _mkdir) {
         const char *p, *e;
         int r;
 
@@ -136,34 +136,54 @@ int mkdir_parents_internal(const char *prefix, const char *path, mode_t mode, mk
                 if (prefix && path_startswith(prefix, t))
                         continue;
 
+                if (uid == UID_INVALID && gid == UID_INVALID && flags == 0) {
                         r = _mkdir(t, mode);
                         if (r < 0 && r != -EEXIST)
                                 return r;
+                } else {
+                        r = mkdir_safe_internal(t, mode, uid, gid, flags, _mkdir);
+                        if (r < 0 && r != -EEXIST)
+                                return r;
                 }
         }
-
-int mkdir_parents(const char *path, mode_t mode) {
-        return mkdir_parents_internal(NULL, path, mode, mkdir_errno_wrapper);
 }
 
-int mkdir_p_internal(const char *prefix, const char *path, mode_t mode, mkdir_func_t _mkdir) {
+int mkdir_parents(const char *path, mode_t mode) {
+        return mkdir_parents_internal(NULL, path, mode, UID_INVALID, UID_INVALID, 0, mkdir_errno_wrapper);
+}
+
+int mkdir_parents_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags) {
+        return mkdir_parents_internal(prefix, path, mode, uid, gid, flags, mkdir_errno_wrapper);
+}
+
+int mkdir_p_internal(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags, mkdir_func_t _mkdir) {
         int r;
 
         /* Like mkdir -p */
 
         assert(_mkdir != mkdir);
 
-        r = mkdir_parents_internal(prefix, path, mode, _mkdir);
+        r = mkdir_parents_internal(prefix, path, mode, uid, gid, flags, _mkdir);
         if (r < 0)
                 return r;
 
+        if (uid == UID_INVALID && gid == UID_INVALID && flags == 0) {
                 r = _mkdir(path, mode);
                 if (r < 0 && (r != -EEXIST || is_dir(path, true) <= 0))
                         return r;
+        } else {
+                r = mkdir_safe_internal(path, mode, uid, gid, flags, _mkdir);
+                if (r < 0 && r != -EEXIST)
+                        return r;
+        }
 
         return 0;
 }
 
 int mkdir_p(const char *path, mode_t mode) {
-        return mkdir_p_internal(NULL, path, mode, mkdir_errno_wrapper);
+        return mkdir_p_internal(NULL, path, mode, UID_INVALID, UID_INVALID, 0, mkdir_errno_wrapper);
+}
+
+int mkdir_p_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags) {
+        return mkdir_p_internal(prefix, path, mode, uid, gid, flags, mkdir_errno_wrapper);
 }

src/basic/mkdir.h

@@ -12,15 +12,17 @@ int mkdir_errno_wrapper(const char *pathname, mode_t mode);
 int mkdirat_errno_wrapper(int dirfd, const char *pathname, mode_t mode);
 int mkdir_safe(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
 int mkdir_parents(const char *path, mode_t mode);
+int mkdir_parents_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
 int mkdir_p(const char *path, mode_t mode);
+int mkdir_p_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
 
 /* mandatory access control(MAC) versions */
 int mkdir_safe_label(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
-int mkdir_parents_label(const char *path, mode_t mode);
+int mkdir_parents_label(const char *path, mode_t mod);
 int mkdir_p_label(const char *path, mode_t mode);
 
 /* internally used */
 typedef int (*mkdir_func_t)(const char *pathname, mode_t mode);
 int mkdir_safe_internal(const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags, mkdir_func_t _mkdir);
-int mkdir_parents_internal(const char *prefix, const char *path, mode_t mode, mkdir_func_t _mkdir);
+int mkdir_parents_internal(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags, mkdir_func_t _mkdir);
-int mkdir_p_internal(const char *prefix, const char *path, mode_t mode, mkdir_func_t _mkdir);
+int mkdir_p_internal(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags, mkdir_func_t _mkdir);

src/core/unit.c

@@ -5955,7 +5955,7 @@ const char *unit_label_path(const Unit *u) {
                 return NULL;
 
         /* If a unit is masked, then don't read the SELinux label of /dev/null, as that really makes no sense */
-        if (path_equal(p, "/dev/null"))
+        if (null_or_empty_path(p) > 0)
                 return NULL;
 
         return p;

src/libsystemd/sd-netlink/netlink-types.c

@@ -93,9 +93,20 @@ static const NLType rtnl_link_info_data_ipvlan_types[] = {
         [IFLA_IPVLAN_FLAGS]  = { .type = NETLINK_TYPE_U16 },
 };
 
+static const NLType rtnl_macvlan_macaddr_types[] = {
+        [IFLA_MACVLAN_MACADDR] = { .type = NETLINK_TYPE_ETHER_ADDR },
+};
+
+static const NLTypeSystem rtnl_macvlan_macaddr_type_system = {
+        .count = ELEMENTSOF(rtnl_macvlan_macaddr_types),
+        .types = rtnl_macvlan_macaddr_types,
+};
+
 static const NLType rtnl_link_info_data_macvlan_types[] = {
         [IFLA_MACVLAN_MODE]  = { .type = NETLINK_TYPE_U32 },
         [IFLA_MACVLAN_FLAGS] = { .type = NETLINK_TYPE_U16 },
+        [IFLA_MACVLAN_MACADDR_MODE] = { .type = NETLINK_TYPE_U32 },
+        [IFLA_MACVLAN_MACADDR_DATA] = { .type = NETLINK_TYPE_NESTED, .type_system = &rtnl_macvlan_macaddr_type_system },
 };
 
 static const NLType rtnl_link_info_data_bridge_types[] = {

src/network/netdev/macvlan.c

@@ -23,6 +23,29 @@ static int netdev_macvlan_fill_message_create(NetDev *netdev, Link *link, sd_net
 
         assert(m);
 
+        if (m->mode == NETDEV_MACVLAN_MODE_SOURCE && !set_isempty(m->match_source_mac)) {
+                Iterator i;
+                const struct ether_addr *mac_addr;
+
+                r = sd_netlink_message_append_u32(req, IFLA_MACVLAN_MACADDR_MODE, MACVLAN_MACADDR_SET);
+                if (r < 0)
+                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_MACVLAN_MACADDR_MODE attribute: %m");
+
+                r = sd_netlink_message_open_container(req, IFLA_MACVLAN_MACADDR_DATA);
+                if (r < 0)
+                        return log_netdev_error_errno(netdev, r, "Could not open IFLA_MACVLAN_MACADDR_DATA container: %m");
+
+                SET_FOREACH(mac_addr, m->match_source_mac, i) {
+                        r = sd_netlink_message_append_ether_addr(req, IFLA_MACVLAN_MACADDR, mac_addr);
+                        if (r < 0)
+                                return log_netdev_error_errno(netdev, r, "Could not append IFLA_MACVLAN_MACADDR attribute: %m");
+                }
+
+                r = sd_netlink_message_close_container(req);
+                if (r < 0)
+                        return log_netdev_error_errno(netdev, r, "Could not close IFLA_MACVLAN_MACADDR_DATA container: %m");
+        }
+
         if (m->mode != _NETDEV_MACVLAN_MODE_INVALID) {
                 r = sd_netlink_message_append_u32(req, IFLA_MACVLAN_MODE, m->mode);
                 if (r < 0)
@@ -32,6 +55,21 @@ static int netdev_macvlan_fill_message_create(NetDev *netdev, Link *link, sd_net
         return 0;
 }
 
+static void macvlan_done(NetDev *n) {
+        MacVlan *m;
+
+        assert(n);
+
+        if (n->kind == NETDEV_KIND_MACVLAN)
+                m = MACVLAN(n);
+        else
+                m = MACVTAP(n);
+
+        assert(m);
+
+        set_free_free(m->match_source_mac);
+}
+
 static void macvlan_init(NetDev *n) {
         MacVlan *m;
 
@@ -50,6 +88,7 @@ static void macvlan_init(NetDev *n) {
 const NetDevVTable macvtap_vtable = {
         .object_size = sizeof(MacVlan),
         .init = macvlan_init,
+        .done = macvlan_done,
         .sections = NETDEV_COMMON_SECTIONS "MACVTAP\0",
         .fill_message_create = netdev_macvlan_fill_message_create,
         .create_type = NETDEV_CREATE_STACKED,
@@ -59,6 +98,7 @@ const NetDevVTable macvtap_vtable = {
 const NetDevVTable macvlan_vtable = {
         .object_size = sizeof(MacVlan),
         .init = macvlan_init,
+        .done = macvlan_done,
         .sections = NETDEV_COMMON_SECTIONS "MACVLAN\0",
         .fill_message_create = netdev_macvlan_fill_message_create,
         .create_type = NETDEV_CREATE_STACKED,

src/network/netdev/macvlan.h

@@ -5,11 +5,13 @@ typedef struct MacVlan MacVlan;
 
 #include "macvlan-util.h"
 #include "netdev.h"
+#include "set.h"
 
 struct MacVlan {
         NetDev meta;
 
         MacVlanMode mode;
+        Set *match_source_mac;
 };
 
 DEFINE_NETDEV_CAST(MACVLAN, MacVlan);

src/network/netdev/netdev-gperf.gperf

@@ -52,7 +52,9 @@ VLAN.MVRP,                                config_parse_tristate,
 VLAN.LooseBinding,                        config_parse_tristate,                     0,                             offsetof(VLan, loose_binding)
 VLAN.ReorderHeader,                       config_parse_tristate,                     0,                             offsetof(VLan, reorder_hdr)
 MACVLAN.Mode,                             config_parse_macvlan_mode,                 0,                             offsetof(MacVlan, mode)
+MACVLAN.SourceMACAddress,                 config_parse_hwaddrs,                      0,                             offsetof(MacVlan, match_source_mac)
 MACVTAP.Mode,                             config_parse_macvlan_mode,                 0,                             offsetof(MacVlan, mode)
+MACVTAP.SourceMACAddress,                 config_parse_hwaddrs,                      0,                             offsetof(MacVlan, match_source_mac)
 IPVLAN.Mode,                              config_parse_ipvlan_mode,                  0,                             offsetof(IPVlan, mode)
 IPVLAN.Flags,                             config_parse_ipvlan_flags,                 0,                             offsetof(IPVlan, flags)
 IPVTAP.Mode,                              config_parse_ipvlan_mode,                  0,                             offsetof(IPVlan, mode)

src/nspawn/nspawn-mount.c

@@ -487,59 +487,6 @@ int mount_sysfs(const char *dest, MountSettingsMask mount_settings) {
                              MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
 }
 
-static int mkdir_userns(const char *path, mode_t mode, uid_t uid_shift) {
-        int r;
-
-        assert(path);
-
-        r = mkdir_errno_wrapper(path, mode);
-        if (r < 0 && r != -EEXIST)
-                return r;
-
-        if (uid_shift == UID_INVALID)
-                return 0;
-
-        if (lchown(path, uid_shift, uid_shift) < 0)
-                return -errno;
-
-        return 0;
-}
-
-static int mkdir_userns_p(const char *prefix, const char *path, mode_t mode, uid_t uid_shift) {
-        const char *p, *e;
-        int r;
-
-        assert(path);
-
-        if (prefix && !path_startswith(path, prefix))
-                return -ENOTDIR;
-
-        /* create every parent directory in the path, except the last component */
-        p = path + strspn(path, "/");
-        for (;;) {
-                char t[strlen(path) + 1];
-
-                e = p + strcspn(p, "/");
-                p = e + strspn(e, "/");
-
-                /* Is this the last component? If so, then we're done */
-                if (*p == 0)
-                        break;
-
-                memcpy(t, path, e - path);
-                t[e-path] = 0;
-
-                if (prefix && path_startswith(prefix, t))
-                        continue;
-
-                r = mkdir_userns(t, mode, uid_shift);
-                if (r < 0)
-                        return r;
-        }
-
-        return mkdir_userns(path, mode, uid_shift);
-}
-
 int mount_all(const char *dest,
               MountSettingsMask mount_settings,
               uid_t uid_shift,
@@ -616,6 +563,10 @@ int mount_all(const char *dest,
                   MOUNT_FATAL|MOUNT_MKDIR },
                 { "tmpfs",                  "/run",                         "tmpfs", "mode=755" TMPFS_LIMITS_RUN,      MS_NOSUID|MS_NODEV|MS_STRICTATIME,
                   MOUNT_FATAL|MOUNT_MKDIR },
+                { "/usr/lib/os-release",    "/run/host/usr/lib/os-release", NULL,    NULL,                             MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,
+                  MOUNT_FATAL|MOUNT_MKDIR|MOUNT_TOUCH },
+                { "/etc/os-release",        "/run/host/etc/os-release",     NULL,    NULL,                             MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,
+                  MOUNT_MKDIR|MOUNT_TOUCH },
 
 #if HAVE_SELINUX
                 { "/sys/fs/selinux",        "/sys/fs/selinux",              NULL,    NULL,                             MS_BIND,
@@ -636,6 +587,7 @@ int mount_all(const char *dest,
         for (k = 0; k < ELEMENTSOF(mount_table); k++) {
                 _cleanup_free_ char *where = NULL, *options = NULL;
                 const char *o;
+                struct stat source_st;
                 bool fatal = FLAGS_SET(mount_table[k].mount_settings, MOUNT_FATAL);
 
                 if (in_userns != FLAGS_SET(mount_table[k].mount_settings, MOUNT_IN_USERNS))
@@ -661,10 +613,26 @@ int mount_all(const char *dest,
                                 return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
                         if (r > 0)
                                 continue;
+
+                        /* Shortcut for optional bind mounts: if the source can't be found skip ahead to avoid creating
+                         * empty and unused directories. */
+                        if (!fatal && FLAGS_SET(mount_table[k].mount_settings, MOUNT_MKDIR) && FLAGS_SET(mount_table[k].flags, MS_BIND)) {
+                                r = stat(mount_table[k].what, &source_st);
+                                if (r < 0) {
+                                        if (errno == ENOENT)
+                                                continue;
+                                        return log_error_errno(errno, "Failed to stat %s: %m", mount_table[k].what);
+                                }
+                        }
                 }
 
                 if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_MKDIR)) {
-                        r = mkdir_userns_p(dest, where, 0755, (use_userns && !in_userns) ? uid_shift : UID_INVALID);
+                        uid_t u = (use_userns && !in_userns) ? uid_shift : UID_INVALID;
+
+                        if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH))
+                                r = mkdir_parents_safe(dest, where, 0755, u, u, 0);
+                        else
+                                r = mkdir_p_safe(dest, where, 0755, u, u, 0);
                         if (r < 0 && r != -EEXIST) {
                                 if (fatal && r != -EROFS)
                                         return log_error_errno(r, "Failed to create directory %s: %m", where);
@@ -676,6 +644,14 @@ int mount_all(const char *dest,
                                 if (r != -EROFS)
                                         continue;
                         }
+                        if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH)) {
+                                r = touch(where);
+                                if (r < 0 && r != -EEXIST) {
+                                        if (fatal)
+                                                return log_error_errno(r, "Failed to create mount point %s: %m", where);
+                                        log_debug_errno(r, "Failed to create mount point %s: %m", where);
+                                }
+                        }
                 }
 
                 o = mount_table[k].options;

src/nspawn/nspawn-mount.h

@@ -17,6 +17,7 @@ typedef enum MountSettingsMask {
         MOUNT_ROOT_ONLY          = 1 << 6, /* if set, only root mounts are mounted */
         MOUNT_NON_ROOT_ONLY      = 1 << 7, /* if set, only non-root mounts are mounted */
         MOUNT_MKDIR              = 1 << 8, /* if set, make directory to mount over first */
+        MOUNT_TOUCH              = 1 << 9, /* if set, touch file to mount over first */
 } MountSettingsMask;
 
 typedef enum CustomMountType {

src/nspawn/nspawn.c

@@ -2931,7 +2931,8 @@ static int inner_child(
                 int kmsg_socket,
                 int rtnl_socket,
                 int master_pty_socket,
-                FDSet *fds) {
+                FDSet *fds,
+                char **os_release_pairs) {
 
         _cleanup_free_ char *home = NULL;
         char as_uuid[ID128_UUID_STRING_MAX];
@@ -3190,7 +3191,7 @@ static int inner_child(
         if (asprintf((char **)(envp + n_env++), "NOTIFY_SOCKET=%s", NSPAWN_NOTIFY_SOCKET_PATH) < 0)
                 return log_oom();
 
-        env_use = strv_env_merge(2, envp, arg_setenv);
+        env_use = strv_env_merge(3, envp, arg_setenv, os_release_pairs);
         if (!env_use)
                 return log_oom();
 
@@ -3316,6 +3317,7 @@ static int outer_child(
                 FDSet *fds,
                 int netns_fd) {
 
+        _cleanup_strv_free_ char **os_release_pairs = NULL;
         _cleanup_close_ int fd = -1;
         const char *p;
         pid_t pid;
@@ -3337,6 +3339,10 @@ static int outer_child(
 
         log_debug("Outer child is initializing.");
 
+        r = load_os_release_pairs_with_prefix("/", "container_host_", &os_release_pairs);
+        if (r < 0)
+                log_debug_errno(r, "Failed to read os-release from host for container, ignoring: %m");
+
         if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
                 return log_error_errno(errno, "PR_SET_PDEATHSIG failed: %m");
 
@@ -3602,7 +3608,7 @@ static int outer_child(
                                 return log_error_errno(r, "Failed to join network namespace: %m");
                 }
 
-                r = inner_child(barrier, directory, secondary, kmsg_socket, rtnl_socket, master_pty_socket, fds);
+                r = inner_child(barrier, directory, secondary, kmsg_socket, rtnl_socket, master_pty_socket, fds, os_release_pairs);
                 if (r < 0)
                         _exit(EXIT_FAILURE);
 

src/portable/portable.c

@@ -701,6 +701,7 @@ static int install_chroot_dropin(
                                "[Service]\n",
                                IN_SET(type, IMAGE_DIRECTORY, IMAGE_SUBVOLUME) ? "RootDirectory=" : "RootImage=", image_path, "\n"
                                "Environment=PORTABLE=", basename(image_path), "\n"
+                               "BindReadOnlyPaths=-/etc/os-release:/run/host/etc/os-release /usr/lib/os-release:/run/host/usr/lib/os-release\n"
                                "LogExtraFields=PORTABLE=", basename(image_path), "\n",
                                NULL))
 

src/shared/install.c

@@ -1236,8 +1236,7 @@ static int unit_file_load(
                                                "%s: unit type %s cannot be templated, ignoring.", path, unit_type_to_string(type));
 
                 if (!(flags & SEARCH_LOAD)) {
-                        r = lstat(path, &st);
+                        if (lstat(path, &st) < 0)
-                        if (r < 0)
                                 return -errno;
 
                         if (null_or_empty(&st))
@@ -1324,26 +1323,40 @@ static int unit_file_load_or_readlink(
                 const char *path,
                 const char *root_dir,
                 SearchFlags flags) {
-
+        _cleanup_free_ char *resolved = NULL;
-        _cleanup_free_ char *target = NULL;
+        struct stat st;
         int r;
 
         r = unit_file_load(c, info, path, root_dir, flags);
         if (r != -ELOOP || (flags & SEARCH_DROPIN))
                 return r;
 
-        /* This is a symlink, let's read it. */
+        r = chase_symlinks(path, root_dir, CHASE_WARN | CHASE_NONEXISTENT, &resolved, NULL);
+        if (r >= 0 &&
+            root_dir &&
+            path_equal_ptr(path_startswith(resolved, root_dir), "dev/null"))
+                /* When looking under root_dir, we can't expect /dev/ to be mounted,
+                 * so let's see if the path is a (possibly dangling) symlink to /dev/null. */
+                info->type = UNIT_FILE_TYPE_MASKED;
+
+        else if (r > 0 &&
+                 stat(resolved, &st) >= 0 &&
+                 null_or_empty(&st))
+
+                info->type = UNIT_FILE_TYPE_MASKED;
+
+        else {
+                _cleanup_free_ char *target = NULL;
+                const char *bn;
+                UnitType a, b;
+
+                /* This is a symlink, let's read it. We read the link again, because last time
+                 * we followed the link until resolution, and here we need to do one step. */
 
                 r = readlink_malloc(path, &target);
                 if (r < 0)
                         return r;
 
-        if (path_equal(target, "/dev/null"))
-                info->type = UNIT_FILE_TYPE_MASKED;
-        else {
-                const char *bn;
-                UnitType a, b;
-
                 bn = basename(target);
 
                 if (unit_name_is_valid(info->name, UNIT_NAME_PLAIN)) {

src/shared/macvlan-util.c

@@ -9,6 +9,7 @@ static const char* const macvlan_mode_table[_NETDEV_MACVLAN_MODE_MAX] = {
         [NETDEV_MACVLAN_MODE_VEPA] = "vepa",
         [NETDEV_MACVLAN_MODE_BRIDGE] = "bridge",
         [NETDEV_MACVLAN_MODE_PASSTHRU] = "passthru",
+        [NETDEV_MACVLAN_MODE_SOURCE] = "source",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(macvlan_mode, MacVlanMode);

src/shared/macvlan-util.h

@@ -8,6 +8,7 @@ typedef enum MacVlanMode {
         NETDEV_MACVLAN_MODE_VEPA = MACVLAN_MODE_VEPA,
         NETDEV_MACVLAN_MODE_BRIDGE = MACVLAN_MODE_BRIDGE,
         NETDEV_MACVLAN_MODE_PASSTHRU = MACVLAN_MODE_PASSTHRU,
+        NETDEV_MACVLAN_MODE_SOURCE = MACVLAN_MODE_SOURCE,
         _NETDEV_MACVLAN_MODE_MAX,
         _NETDEV_MACVLAN_MODE_INVALID = -1
 } MacVlanMode;

src/shared/os-util.c

@@ -117,3 +117,33 @@ int load_os_release_pairs(const char *root, char ***ret) {
 
         return load_env_file_pairs(f, p, ret);
 }
+
+int load_os_release_pairs_with_prefix(const char *root, const char *prefix, char ***ret) {
+        _cleanup_strv_free_ char **os_release_pairs = NULL, **os_release_pairs_prefixed = NULL;
+        char **p, **q;
+        int r;
+
+        r = load_os_release_pairs(root, &os_release_pairs);
+        if (r < 0)
+                return r;
+
+        STRV_FOREACH_PAIR(p, q, os_release_pairs) {
+                char *line;
+
+                // We strictly return only the four main ID fields and ignore the rest
+                if (!STR_IN_SET(*p, "ID", "VERSION_ID", "BUILD_ID", "VARIANT_ID"))
+                        continue;
+
+                ascii_strlower(*p);
+                line = strjoin(prefix, *p, "=", *q);
+                if (!line)
+                        return -ENOMEM;
+                r = strv_consume(&os_release_pairs_prefixed, line);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(os_release_pairs_prefixed);
+
+        return 0;
+}

src/shared/os-util.h

@@ -10,3 +10,4 @@ int fopen_os_release(const char *root, char **ret_path, FILE **ret_file);
 
 int parse_os_release(const char *root, ...) _sentinel_;
 int load_os_release_pairs(const char *root, char ***ret);
+int load_os_release_pairs_with_prefix(const char *root, const char *prefix, char ***ret);

src/test/test-install-root.c

@@ -4,6 +4,7 @@
 
 #include "alloc-util.h"
 #include "fileio.h"
+#include "fs-util.h"
 #include "install.h"
 #include "mkdir.h"
 #include "rm-rf.h"
@@ -23,6 +24,7 @@ static void test_basic_mask_and_enable(const char *root) {
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", NULL) == -ENOENT);
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", NULL) == -ENOENT);
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", NULL) == -ENOENT);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "e.service", NULL) == -ENOENT);
 
         p = strjoina(root, "/usr/lib/systemd/system/a.service");
         assert_se(write_string_file(p,
@@ -150,6 +152,22 @@ static void test_basic_mask_and_enable(const char *root) {
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "b.service", &state) >= 0 && state == UNIT_FILE_ALIAS);
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "c.service", &state) >= 0 && state == UNIT_FILE_ALIAS);
         assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "d.service", &state) >= 0 && state == UNIT_FILE_ALIAS);
+
+        /* Test masking with relative symlinks */
+
+        p = strjoina(root, "/usr/lib/systemd/system/e.service");
+        assert_se(symlink("../../../../../../dev/null", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "e.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "e.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+
+        assert_se(unlink(p) == 0);
+        assert_se(symlink("/usr/../dev/null", p) >= 0);
+
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "e.service", NULL) >= 0);
+        assert_se(unit_file_get_state(UNIT_FILE_SYSTEM, root, "e.service", &state) >= 0 && state == UNIT_FILE_MASKED);
+
+        assert_se(unlink(p) == 0);
 }
 
 static void test_linked_units(const char *root) {

test/TEST-13-NSPAWN-SMOKE/test.sh

@@ -16,7 +16,7 @@ test_create_image() {
         mask_supporting_services
 
         ../create-busybox-container $initdir/testsuite-13.nc-container
-        initdir="$initdir/testsuite-13.nc-container" dracut_install nc ip
+        initdir="$initdir/testsuite-13.nc-container" dracut_install nc ip md5sum
     )
 }
 

test/fuzz/fuzz-netdev-parser/directives.netdev

@@ -6,6 +6,7 @@ Id=
 GVRP=
 [MACVLAN]
 Mode=
+SourceMACAddress=
 [WireGuard]
 ListenPort=
 PrivateKey=
@@ -14,6 +15,7 @@ FwMark=
 FirewallMark=
 [MACVTAP]
 Mode=
+SourceMACAddress=
 [Match]
 Architecture=
 Host=

test/units/testsuite-13.sh

@@ -60,6 +60,18 @@ function check_notification_socket {
     systemd-nspawn --register=no -D /testsuite-13.nc-container -U /bin/sh -x -c "$_cmd"
 }
 
+function check_os_release {
+    local _cmd='. /tmp/os-release
+if [ -n "${ID:+set}" ] && [ "${ID}" != "${container_host_id}" ]; then exit 1; fi
+if [ -n "${VERSION_ID:+set}" ] && [ "${VERSION_ID}" != "${container_host_version_id}" ]; then exit 1; fi
+if [ -n "${BUILD_ID:+set}" ] && [ "${BUILD_ID}" != "${container_host_build_id}" ]; then exit 1; fi
+if [ -n "${VARIANT_ID:+set}" ] && [ "${VARIANT_ID}" != "${container_host_variant_id}" ]; then exit 1; fi
+cd /tmp; (cd /run/host/usr/lib; md5sum os-release) | md5sum -c
+'
+
+    systemd-nspawn --register=no -D /testsuite-13.nc-container --bind=/etc/os-release:/tmp/os-release /bin/sh -x -e -c "$_cmd"
+}
+
 function run {
     if [[ "$1" = "yes" && "$is_v2_supported" = "no" ]]; then
         printf "Unified cgroup hierarchy is not supported. Skipping.\n" >&2
@@ -144,6 +156,8 @@ check_norbind
 
 check_notification_socket
 
+check_os_release
+
 for api_vfs_writable in yes no network; do
     run no no $api_vfs_writable
     run yes no $api_vfs_writable