From d49d646d00078b201cdde2978b7941d20acb1d4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Wed, 2 Mar 2022 16:53:54 +0100
Subject: [PATCH] basic/unit-file: split out the subroutine for symlink
verification
The old logs used __func__, but this doesn't make sense now, because the
low-level function will be used in other places. So those are adjusted to be
more generic.
(cherry picked from commit 9825181143530af7003fc50567b814dbbee39046)
Related: #2082131
---
src/basic/unit-file.c | 159 +++++++++++++++++++++++++-----------------
1 file changed, 96 insertions(+), 63 deletions(-)
diff --git a/src/basic/unit-file.c b/src/basic/unit-file.c
index 96826e2940..25abce932a 100644
--- a/src/basic/unit-file.c
+++ b/src/basic/unit-file.c
@@ -260,6 +260,83 @@ static int directory_name_is_valid(const char *name) {
return false;
}
+static int unit_file_resolve_symlink(
+ const char *root_dir,
+ char **search_path,
+ const char *dir,
+ int dirfd,
+ const char *filename,
+ char **ret_destination) {
+
+ _cleanup_free_ char *target = NULL, *simplified = NULL, *dst = NULL;
+ int r;
+
+ assert(dir);
+ assert(dirfd >= 0);
+ assert(filename);
+ assert(ret_destination);
+
+ r = readlinkat_malloc(dirfd, filename, &target);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to read symlink %s%s%s: %m",
+ dir, dir ? "/" : "", filename);
+
+ bool is_abs = path_is_absolute(target);
+ if (root_dir || !is_abs) {
+ char *target_abs = path_join(is_abs ? root_dir : dir, target);
+ if (!target_abs)
+ return log_oom();
+
+ free_and_replace(target, target_abs);
+ }
+
+ /* Get rid of "." and ".." components in target path */
+ r = chase_symlinks(target, root_dir, CHASE_NOFOLLOW | CHASE_NONEXISTENT, &simplified, NULL);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to resolve symlink %s/%s pointing to %s: %m",
+ dir, filename, target);
+
+ /* Check if the symlink goes outside of our search path.
+ * If yes, it's a linked unit file or mask, and we don't care about the target name.
+ * Let's just store the link source directly.
+ * If not, let's verify that it's a good symlink. */
+ const char *tail = path_startswith_strv(simplified, search_path);
+ if (!tail) {
+ log_debug("Linked unit file: %s/%s → %s", dir, filename, simplified);
+
+ dst = path_join(dir, filename);
+ if (!dst)
+ return log_oom();
+
+ } else {
+ r = path_extract_filename(simplified, &dst);
+ if (r < 0)
+ return r;
+
+ bool self_alias = streq(dst, filename);
+
+ if (is_path(tail))
+ log_full(self_alias ? LOG_DEBUG : LOG_WARNING,
+ "Suspicious symlink %s/%s→%s, treating as alias.",
+ dir, filename, simplified);
+
+ r = unit_validate_alias_symlink_and_warn(filename, simplified);
+ if (r < 0)
+ return r;
+
+ if (self_alias)
+ /* A self-alias that has no effect */
+ return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
+ "Unit file self-alias: %s/%s → %s, ignoring.",
+ dir, filename, dst);
+
+ log_debug("Unit file alias: %s/%s → %s", dir, filename, dst);
+ }
+
+ *ret_destination = TAKE_PTR(dst);
+ return 0;
+}
+
int unit_file_build_name_map(
const LookupPaths *lp,
uint64_t *cache_timestamp_hash,
@@ -310,10 +387,9 @@ int unit_file_build_name_map(
FOREACH_DIRENT_ALL(de, d, log_warning_errno(errno, "Failed to read \"%s\", ignoring: %m", *dir)) {
_unused_ _cleanup_free_ char *_filename_free = NULL;
- _cleanup_free_ char *simplified = NULL;
- bool symlink_to_dir = false;
- const char *dst = NULL;
char *filename;
+ _cleanup_free_ char *dst = NULL;
+ bool symlink_to_dir = false;
/* We only care about valid units and dirs with certain suffixes, let's ignore the
* rest. */
@@ -397,77 +473,34 @@ int unit_file_build_name_map(
/* We don't explicitly check for alias loops here. unit_ids_map_get() which
* limits the number of hops should be used to access the map. */
- _cleanup_free_ char *target = NULL;
-
- r = readlinkat_malloc(dirfd(d), de->d_name, &target);
- if (r < 0) {
- log_warning_errno(r, "Failed to read symlink %s/%s, ignoring: %m",
- *dir, de->d_name);
+ r = unit_file_resolve_symlink(lp->root_dir, lp->search_path,
+ *dir, dirfd(d), de->d_name,
+ &dst);
+ if (r == -ENOMEM)
+ return r;
+ if (r < 0) /* we ignore other errors here */
continue;
- }
- const bool is_abs = path_is_absolute(target);
- if (lp->root_dir || !is_abs) {
- char *target_abs = path_join(is_abs ? lp->root_dir : *dir, target);
- if (!target_abs)
+ } else {
+ dst = TAKE_PTR(_filename_free); /* Grab the copy we made previously, if available. */
+ if (!dst) {
+ dst = strdup(filename);
+ if (!dst)
return log_oom();
-
- free_and_replace(target, target_abs);
}
- /* Get rid of "." and ".." components in target path */
- r = chase_symlinks(target, lp->root_dir, CHASE_NOFOLLOW | CHASE_NONEXISTENT, &simplified, NULL);
- if (r < 0) {
- log_warning_errno(r, "Failed to resolve symlink %s pointing to %s, ignoring: %m",
- filename, target);
- continue;
- }
-
- /* Check if the symlink goes outside of our search path.
- * If yes, it's a linked unit file or mask, and we don't care about the target name.
- * Let's just store the link source directly.
- * If not, let's verify that it's a good symlink. */
- char *tail = path_startswith_strv(simplified, lp->search_path);
- if (!tail) {
- log_debug("%s: linked unit file: %s → %s",
- __func__, filename, simplified);
-
- dst = filename;
- } else {
-
- bool self_alias;
-
- dst = basename(simplified);
- self_alias = streq(dst, de->d_name);
-
- if (is_path(tail))
- log_full(self_alias ? LOG_DEBUG : LOG_WARNING,
- "Suspicious symlink %s→%s, treating as alias.",
- filename, simplified);
-
- r = unit_validate_alias_symlink_and_warn(filename, simplified);
- if (r < 0)
- continue;
-
- if (self_alias) {
- /* A self-alias that has no effect */
- log_debug("%s: self-alias: %s/%s → %s, ignoring.",
- __func__, *dir, de->d_name, dst);
- continue;
- }
-
- log_debug("%s: alias: %s/%s → %s", __func__, *dir, de->d_name, dst);
- }
-
- } else {
- dst = filename;
log_debug("%s: normal unit file: %s", __func__, dst);
}
- r = hashmap_put_strdup(&ids, de->d_name, dst);
+ _cleanup_free_ char *key = strdup(de->d_name);
+ if (!key)
+ return log_oom();
+
+ r = hashmap_ensure_put(&ids, &string_hash_ops_free_free, key, dst);
if (r < 0)
return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m",
de->d_name, dst);
+ key = dst = NULL;
}
}