From cedab11bf07cdb5275ac12104d4dad6debbedce4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Sat, 28 Nov 2015 18:41:08 -0500
Subject: [PATCH] acl-util: only set the mask if not present
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When we have non-owner user or group entries, we need the mask
for the acl to be valid. But acl_calc_mask() calculates the mask
to include all permissions, even those that were masked before.
Apparently this happens when we inherit *:r-x permissions from
a parent directory — the kernel sets *:r-x, mask:r--, effectively
masking the executable bit. acl_calc_mask() would set the mask:r-x,
effectively enabling the bit. To avoid this, be more conservative when
to add the mask entry: first iterate over all entries, and do nothing
if a mask.

This returns the code closer to J.A.Steffens' original version
in v204-90-g23ad4dd884.

Should fix https://github.com/systemd/systemd/issues/1977.

(cherry picked from commit 6debb3982612b1fce9b2dd878bad07fe5ae9c0a9)

Resolves: #2026361
---
 src/shared/acl-util.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/shared/acl-util.c b/src/shared/acl-util.c
index d18a02f503..ec08661167 100644
--- a/src/shared/acl-util.c
+++ b/src/shared/acl-util.c
@@ -69,6 +69,7 @@ int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *entry) {
 int calc_acl_mask_if_needed(acl_t *acl_p) {
         acl_entry_t i;
         int r;
+        bool need = false;
 
         assert(acl_p);
 
@@ -83,17 +84,16 @@ int calc_acl_mask_if_needed(acl_t *acl_p) {
                 if (tag == ACL_MASK)
                         return 0;
 
-                if (IN_SET(tag, ACL_USER, ACL_GROUP)) {
-                        if (acl_calc_mask(acl_p) < 0)
-                                return -errno;
-
-                        return 1;
-                }
+                if (IN_SET(tag, ACL_USER, ACL_GROUP))
+                        need = true;
         }
         if (r < 0)
                 return -errno;
 
-        return 0;
+        if (need && acl_calc_mask(acl_p) < 0)
+                return -errno;
+
+        return need;
 }
 
 int add_base_acls_if_needed(acl_t *acl_p, const char *path) {