[newlib-cygwin/cygwin-3_4-branch] Cygwin: chmod: don't drop default ACEs from directory ACLs

Corinna Vinschen corinna@sourceware.org
Thu Feb 9 21:01:20 GMT 2023


commit b66979e1523eea3fbcec9b831442881571b83242
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Thu Feb 9 21:47:15 2023 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Thu Feb 9 21:59:47 2023 +0100

    Cygwin: chmod: don't drop default ACEs from directory ACLs
    commit bc444e5aa4ca introduced a call to get_posix_access()
    with a NULL pointer for the mode_t parameter because the value
    is not needed later on... entirely ignoring the fact that the
    mode_t bits are checked for the object being a directory.
    In turn, the get_posix_access() call never checked for default
    ACEs and returned only the standard ACEs.  Thus, every chmod call
    on a directory dropped the default ACEs from its permissions, as
    well as the default NULL deny-ACE used to store specific bits.
    It got also impossible to set the sgid bit on directories.
    Fixes: bc444e5aa4ca ("Reapply POSIX ACL changes.")
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

 winsup/cygwin/fhandler/disk_file.cc | 3 ++-
 winsup/cygwin/release/3.4.6         | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/fhandler/disk_file.cc b/winsup/cygwin/fhandler/disk_file.cc
index 6eb466e9c6f4..15dc24ffef62 100644
--- a/winsup/cygwin/fhandler/disk_file.cc
+++ b/winsup/cygwin/fhandler/disk_file.cc
@@ -764,11 +764,12 @@ fhandler_disk_file::fchmod (mode_t mode)
       aclent_t *aclp;
       bool standard_acl = false;
       int nentries, idx;
+      mode_t attr = pc.isdir () ? S_IFDIR : 0;
       if (!get_file_sd (get_handle (), pc, sd, false))
 	  aclp = (aclent_t *) tp.c_get ();
-	  if ((nentries = get_posix_access (sd, NULL, &uid, &gid,
+	  if ((nentries = get_posix_access (sd, &attr, &uid, &gid,
 					    aclp, MAX_ACL_ENTRIES,
 					    &standard_acl)) >= 0)
diff --git a/winsup/cygwin/release/3.4.6 b/winsup/cygwin/release/3.4.6
index f9288dc79994..ccc168a9587f 100644
--- a/winsup/cygwin/release/3.4.6
+++ b/winsup/cygwin/release/3.4.6
@@ -9,3 +9,6 @@ Addresses: https://cygwin.com/pipermail/cygwin/2023-January/252928.html
 Create directories with correctly umask-filtered default ACEs.
 Addresses: https://cygwin.com/pipermail/cygwin/2023-February/253037.html
+Don't accidentally drop the default ACEs when chmod'ing directories.
+Addresses: https://cygwin.com/pipermail/cygwin/2023-February/253037.html

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