Merge pull request #9255 from poettering/block-dev-fixes

some block device handling fixes

src/basic/blockdev-util.c

@@ -81,38 +81,26 @@ int get_block_device(const char *path, dev_t *dev) {
         if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
                 return btrfs_get_block_device(path, dev);
 
+        *dev = 0;
         return 0;
 }
 
-int get_block_device_harder(const char *path, dev_t *dev) {
+int block_get_originating(dev_t dt, dev_t *ret) {
         _cleanup_closedir_ DIR *d = NULL;
         _cleanup_free_ char *t = NULL;
         char p[SYS_BLOCK_PATH_MAX("/slaves")];
         struct dirent *de, *found = NULL;
-        const char *q;
         unsigned maj, min;
-        dev_t dt;
+        const char *q;
         int r;
 
-        assert(path);
-        assert(dev);
-
-        /* Gets the backing block device for a file system, and
-         * handles LUKS encrypted file systems, looking for its
-         * immediate parent, if there is one. */
-
-        r = get_block_device(path, &dt);
-        if (r <= 0)
-                return r;
+        /* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
+         * trying to find the next underlying layer.  */
 
         xsprintf_sys_block_path(p, "/slaves", dt);
         d = opendir(p);
-        if (!d) {
-                if (errno == ENOENT)
-                        goto fallback;
-
+        if (!d)
                 return -errno;
-        }
 
         FOREACH_DIRENT_ALL(de, d, return -errno) {
 
@@ -140,34 +128,28 @@ int get_block_device_harder(const char *path, dev_t *dev) {
                                 return -ENOMEM;
 
                         r = read_one_line_file(u, &a);
-                        if (r < 0) {
-                                log_debug_errno(r, "Failed to read %s: %m", u);
-                                goto fallback;
-                        }
+                        if (r < 0)
+                                return log_debug_errno(r, "Failed to read %s: %m", u);
 
                         r = read_one_line_file(v, &b);
-                        if (r < 0) {
-                                log_debug_errno(r, "Failed to read %s: %m", v);
-                                goto fallback;
-                        }
+                        if (r < 0)
+                                return log_debug_errno(r, "Failed to read %s: %m", v);
 
                         /* Check if the parent device is the same. If not, then the two backing devices are on
                          * different physical devices, and we don't support that. */
                         if (!streq(a, b))
-                                goto fallback;
+                                return -ENOTUNIQ;
                 }
 
                 found = de;
         }
 
         if (!found)
-                goto fallback;
+                return -ENOENT;
 
         q = strjoina(p, "/", found->d_name, "/dev");
 
         r = read_one_line_file(q, &t);
-        if (r == -ENOENT)
-                goto fallback;
         if (r < 0)
                 return r;
 
@@ -175,12 +157,28 @@ int get_block_device_harder(const char *path, dev_t *dev) {
                 return -EINVAL;
 
         if (maj == 0)
-                goto fallback;
+                return -ENOENT;
+
+        *ret = makedev(maj, min);
+        return 1;
+}
+
+int get_block_device_harder(const char *path, dev_t *ret) {
+        int r;
+
+        assert(path);
+        assert(ret);
+
+        /* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
+         * immediate parent, if there is one. */
+
+        r = get_block_device(path, ret);
+        if (r <= 0)
+                return r;
+
+        r = block_get_originating(*ret, ret);
+        if (r < 0)
+                log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
 
-        *dev = makedev(maj, min);
-        return 1;
-
-fallback:
-        *dev = dt;
         return 1;
 }

src/basic/blockdev-util.h

@@ -19,6 +19,7 @@
         xsprintf(buf, "/sys/dev/block/%u:%u%s", major(devno), minor(devno), strempty(suffix))
 
 int block_get_whole_disk(dev_t d, dev_t *ret);
+int block_get_originating(dev_t d, dev_t *ret);
 
 int get_block_device(const char *path, dev_t *dev);
 

src/basic/btrfs-util.c

@@ -277,8 +277,10 @@ int btrfs_get_block_device_fd(int fd, dev_t *dev) {
                 return -errno;
 
         /* We won't do this for btrfs RAID */
-        if (fsi.num_devices != 1)
+        if (fsi.num_devices != 1) {
+                *dev = 0;
                 return 0;
+        }
 
         for (id = 1; id <= fsi.max_id; id++) {
                 struct btrfs_ioctl_dev_info_args di = {

src/basic/path-util.c

@@ -886,17 +886,36 @@ bool hidden_or_backup_file(const char *filename) {
 
 bool is_device_path(const char *path) {
 
-        /* Returns true on paths that refer to a device, either in
-         * sysfs or in /dev */
+        /* Returns true on paths that likely refer to a device, either by path in sysfs or to something in /dev */
 
-        return path_startswith(path, "/dev/") ||
-               path_startswith(path, "/sys/");
+        return PATH_STARTSWITH_SET(path, "/dev/", "/sys/");
 }
 
-bool is_deviceallow_pattern(const char *path) {
-        return path_startswith(path, "/dev/") ||
-               startswith(path, "block-") ||
-               startswith(path, "char-");
+bool valid_device_node_path(const char *path) {
+
+        /* Some superficial checks whether the specified path is a valid device node path, all without looking at the
+         * actual device node. */
+
+        if (!PATH_STARTSWITH_SET(path, "/dev/", "/run/systemd/inaccessible/"))
+                return false;
+
+        if (endswith(path, "/")) /* can't be a device node if it ends in a slash */
+                return false;
+
+        return path_is_normalized(path);
+}
+
+bool valid_device_allow_pattern(const char *path) {
+        assert(path);
+
+        /* Like valid_device_node_path(), but also allows full-subsystem expressions, like DeviceAllow= and DeviceDeny=
+         * accept it */
+
+        if (startswith(path, "block-") ||
+            startswith(path, "char-"))
+                return true;
+
+        return valid_device_node_path(path);
 }
 
 int systemd_installation_has_version(const char *root, unsigned minimal_version) {

src/basic/path-util.h

@@ -147,7 +147,9 @@ char *file_in_same_dir(const char *path, const char *filename);
 bool hidden_or_backup_file(const char *filename) _pure_;
 
 bool is_device_path(const char *path);
-bool is_deviceallow_pattern(const char *path);
+
+bool valid_device_node_path(const char *path);
+bool valid_device_allow_pattern(const char *path);
 
 int systemd_installation_has_version(const char *root, unsigned minimal_version);