From b060c53503339c45808efeb4294a03105a2999a5 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 2 Feb 2022 14:05:45 +0900
Subject: [PATCH] mkdir: allow to create directory whose path contains symlink
Cc: pavel@zhukoff.net

Upstream-Status: Backport
Upstream-Url: https://github.com/systemd/systemd/pull/22359

Signed-off-by: Pavel Zhukov <pavel.zhukov@huawei.com>


core/mount: fail early if directory cannot be created

Prompted by #22334.

mkdir: CHASE_NONEXISTENT cannot used in chase_symlinks_and_stat()

mkdir: allow to create directory whose path contains symlink

Fixes a regression caused by 3008a6f21c1c42efe852d69798a2fdd63fe657ec.

Before the commit, when `mkdir_parents_internal()` is called from `mkdir_p()`,
it uses `_mkdir()` as `flag` is zero. But after the commit, `mkdir_safe_internal()`
is always used. Hence, if the path contains a symlink, it fails with -ENOTDIR.

To fix the issue, this makes `mkdir_p()` calls `mkdir_parents_internal()` with
MKDIR_FOLLOW_SYMLINK flag.

Fixes #22334.

test: add a test for mkdir_p()
---
 src/basic/mkdir.c     |  4 ++--
 src/core/mount.c      |  4 +++-
 src/test/meson.build  |  2 ++
 src/test/test-mkdir.c | 30 ++++++++++++++++++++++++++++++
 4 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 src/test/test-mkdir.c

diff --git a/src/basic/mkdir.c b/src/basic/mkdir.c
index 6e2b94d024..51a0d74e87 100644
--- a/src/basic/mkdir.c
+++ b/src/basic/mkdir.c
@@ -42,7 +42,7 @@ int mkdir_safe_internal(
         if ((flags & MKDIR_FOLLOW_SYMLINK) && S_ISLNK(st.st_mode)) {
                 _cleanup_free_ char *p = NULL;
 
-                r = chase_symlinks_and_stat(path, NULL, CHASE_NONEXISTENT, &p, &st, NULL);
+                r = chase_symlinks_and_stat(path, NULL, 0, &p, &st, NULL);
                 if (r < 0)
                         return r;
                 if (r == 0)
@@ -162,7 +162,7 @@ int mkdir_p_internal(const char *prefix, const char *path, mode_t mode, uid_t ui
 
         assert(_mkdirat != mkdirat);
 
-        r = mkdir_parents_internal(prefix, path, mode, uid, gid, flags, _mkdirat);
+        r = mkdir_parents_internal(prefix, path, mode, uid, gid, flags | MKDIR_FOLLOW_SYMLINK, _mkdirat);
         if (r < 0)
                 return r;
 
diff --git a/src/core/mount.c b/src/core/mount.c
index 0170406351..c650b5abe2 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -1027,8 +1027,10 @@ static void mount_enter_mounting(Mount *m) {
                 r = mkdir_p_label(p->what, m->directory_mode);
                 /* mkdir_p_label() can return -EEXIST if the target path exists and is not a directory - which is
                  * totally OK, in case the user wants us to overmount a non-directory inode. */
-                if (r < 0 && r != -EEXIST)
+                if (r < 0 && r != -EEXIST) {
                         log_unit_error_errno(UNIT(m), r, "Failed to make bind mount source '%s': %m", p->what);
+                        goto fail;
+                }
         }
 
         if (p) {
diff --git a/src/test/meson.build b/src/test/meson.build
index 9a1c481f22..7aa1d9c6ea 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -193,6 +193,8 @@ tests += [
 
         [['src/test/test-macro.c']],
 
+        [['src/test/test-mkdir.c']],
+
         [['src/test/test-json.c']],
 
         [['src/test/test-modhex.c']],
diff --git a/src/test/test-mkdir.c b/src/test/test-mkdir.c
new file mode 100644
index 0000000000..c715d5f096
--- /dev/null
+++ b/src/test/test-mkdir.c
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+
+#include "mkdir.h"
+#include "path-util.h"
+#include "rm-rf.h"
+#include "tests.h"
+#include "tmpfile-util.h"
+
+TEST(mkdir_p) {
+        _cleanup_(rm_rf_physical_and_freep) char *tmp = NULL;
+        _cleanup_free_ char *p = NULL;
+
+        assert_se(mkdtemp_malloc("/tmp/test-mkdir-XXXXXX", &tmp) >= 0);
+
+        assert_se(p = path_join(tmp, "run"));
+        assert_se(mkdir_p(p, 0755) >= 0);
+
+        p = mfree(p);
+        assert_se(p = path_join(tmp, "var/run"));
+        assert_se(mkdir_parents(p, 0755) >= 0);
+        assert_se(symlink("../run", p) >= 0);
+
+        p = mfree(p);
+        assert_se(p = path_join(tmp, "var/run/hoge/foo/baz"));
+        assert_se(mkdir_p(p, 0755) >= 0);
+}
+
+DEFINE_TEST_MAIN(LOG_DEBUG);
-- 
2.34.1