Merge pull request #742 from flatcar/krnowak/split-base-image-var-conf

build_library: Split `base_image_var.conf` into two config files

build_library/build_image_util.sh

@@ -744,11 +744,34 @@ finish_image() {
   done
   # Record directories installed to the state partition.
   # Explicitly ignore entries covered by existing configs.
-  local tmp_ignore=$(awk '/^[dDfFL]/ {print "--ignore=" $2}' \
+  local ignores=() allowed_users=() allowed_groups=()
+  mapfile -t ignores < <(awk '/^[dDfFL]/ {print "--ignore=" $2}' \
                              "${root_fs_dir}"/usr/lib/tmpfiles.d/*.conf)
+  # Also ignore directories owned by users/groups not in /etc/passwd
+  # or /etc/group. This is for setting up needed directories in very
+  # early boot phase (initrd-setup-root). Our source of truth for
+  # allowed users and groups are users and groups copied by the
+  # flatcar-tmpfiles script.
+
+  # The grep, sed and tr below basically turn a line like:
+  # COPY_USERS="root|core"
+  # into:
+  # --allow-user=root
+  # --allow-user=core
+  mapfile -t allowed_users < <(grep '^COPY_USERS=' "${root_fs_dir}/sbin/flatcar-tmpfiles" | sed -e 's/.*="\([^"]*\)"/\1/' | tr '|' '\n' | sed -e 's/^/--allow-user=/')
+  mapfile -t allowed_users < <(grep '^COPY_GROUPS=' "${root_fs_dir}/sbin/flatcar-tmpfiles" | sed -e 's/.*="\([^"]*\)"/\1/' | tr '|' '\n' | sed -e 's/^/--allow-group=/')
   sudo "${BUILD_LIBRARY_DIR}/gen_tmpfiles.py" --root="${root_fs_dir}" \
       --output="${root_fs_dir}/usr/lib/tmpfiles.d/base_image_var.conf" \
-      ${tmp_ignore} "${root_fs_dir}/var"
+      "${ignores[@]}" "${allowed_users[@]}" "${allowed_groups[@]}" "${root_fs_dir}/var"
+
+  # Now record the rest of the directories installed to the state
+  # partition. We go through tmpfiles again to also ignore the entries
+  # from the just generated base_image_var.conf.
+  mapfile -t ignores < <(awk '/^[dDfFL]/ {print "--ignore=" $2}' \
+                             "${root_fs_dir}"/usr/lib/tmpfiles.d/*.conf)
+  sudo "${BUILD_LIBRARY_DIR}/gen_tmpfiles.py" --root="${root_fs_dir}" \
+      --output="${root_fs_dir}/usr/lib/tmpfiles.d/base_image_var_late.conf" \
+      "${ignores[@]}" "${root_fs_dir}/var"
 
   # Only configure bootloaders if there is a boot partition
   if mountpoint -q "${root_fs_dir}"/boot; then

build_library/gen_tmpfiles.py

@@ -21,8 +21,15 @@ def main():
     parser.add_option('--output', help='Write output to the given file')
     parser.add_option('--ignore', action='append', default=[],
                       help='Ignore one or more paths (use multiple times)')
+    parser.add_option('--allow-user', action='append', default=[],
+                      help='Allow entries owned by this user only (use multiple times for multiple users)')
+    parser.add_option('--allow-group', action='append', default=[],
+                      help='Allow entries owned by this group only (use multiple times for multiple groups)')
     opts, args = parser.parse_args()
 
+    allowed_users = set(opts.allow_user)
+    allowed_groups = set(opts.allow_group)
+
     if opts.root:
         opts.root = os.path.abspath(opts.root)
 
@@ -67,10 +74,14 @@ def main():
 
         try:
             owner = pwd.getpwuid(info.st_uid).pw_name
+            if allowed_users and owner not in allowed_users:
+                continue
         except KeyError:
             owner = str(info.st_uid)
         try:
             group = grp.getgrgid(info.st_gid).gr_name
+            if allowed_groups and group not in allowed_groups:
+                continue
         except KeyError:
             group = str(info.st_gid)