From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 30 Mar 2023 04:15:59 +0000 (+0900)
Subject: chase: drop CHASE_AT_RESOLVE_IN_ROOT when AT_FDCWD or root dir fd is specified
X-Git-Tag: v254-rc1~863^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e115daa6a8f0cc80591228e4c6f651b9afc66b30;p=thirdparty%2Fsystemd.git

chase: drop CHASE_AT_RESOLVE_IN_ROOT when AT_FDCWD or root dir fd is specified

If we get AT_FDCWD or root dir fd, we always resolve symlinks relative to the host's root.
Hence, the flag is meaningless.
---

diff --git a/src/basic/chase.c b/src/basic/chase.c
index 6c02aeab8ba..7b7664096f7 100644
--- a/src/basic/chase.c
+++ b/src/basic/chase.c
@@ -164,6 +164,20 @@ int chaseat(
          *    the mount point is emitted. CHASE_WARN cannot be used in PID 1.
          */
 
+        if (FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)) {
+                /* If we get AT_FDCWD or dir_fd points to "/", then we always resolve symlinks relative to
+                 * the host's root. Hence, CHASE_AT_RESOLVE_IN_ROOT is meaningless. */
+
+                if (dir_fd >= 0)
+                        r = dir_fd_is_root(dir_fd);
+                else
+                        r = true;
+                if (r < 0)
+                        return r;
+                if (r > 0)
+                        flags &= ~CHASE_AT_RESOLVE_IN_ROOT;
+        }
+
         if (!(flags &
               (CHASE_AT_RESOLVE_IN_ROOT|CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_STEP|
                CHASE_PROHIBIT_SYMLINKS|CHASE_MKDIR_0755)) &&