nspawn: optionally fix up OS tree uid/gids for userns

This adds a new --private-userns-chown switch that may be used in combination
with --private-userns. If it is passed a recursive chmod() operation is run on
the OS tree, fixing all file owner UID/GIDs to the right ranges. This should
make user namespacing pretty workable, as the OS trees don't need to be
prepared manually anymore.

1 files changed, 61 insertions, 0 deletions

diff --git a/src/nspawn/test-patch-uid.c b/src/nspawn/test-patch-uid.c
new file mode 100644
index 0000000000..11c5321788
--- /dev/null
+++ b/src/nspawn/test-patch-uid.c
@@ -0,0 +1,61 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+
+#include "log.h"
+#include "nspawn-patch-uid.h"
+#include "user-util.h"
+#include "util.h"
+
+int main(int argc, char *argv[]) {
+        uid_t shift, range;
+        int r;
+
+        log_set_max_level(LOG_DEBUG);
+        log_parse_environment();
+        log_open();
+
+        if (argc != 4) {
+                log_error("Expected PATH SHIFT RANGE parameters.");
+                return EXIT_FAILURE;
+        }
+
+        r = parse_uid(argv[2], &shift);
+        if (r < 0) {
+                log_error_errno(r, "Failed to parse UID shift %s.", argv[2]);
+                return EXIT_FAILURE;
+        }
+
+        r = parse_gid(argv[3], &range);
+        if (r < 0) {
+                log_error_errno(r, "Failed to parse UID range %s.", argv[3]);
+                return EXIT_FAILURE;
+        }
+
+        r = path_patch_uid(argv[1], shift, range);
+        if (r < 0) {
+                log_error_errno(r, "Failed to patch directory tree: %m");
+                return EXIT_FAILURE;
+        }
+
+        log_info("Changed: %s", yes_no(r));
+
+        return EXIT_SUCCESS;
+}