s3:smbd: fix posix acls when setting an ACL without explicit ACE for the owner (bug#2346)

The problem of bug #2346 remains for users exported by
winbindd, because create_token_from_username() just fakes
the token when the user is not in the local sam domain. This causes
user_in_group_sid() to give totally wrong results.
In uid_entry_in_group() we need to check if we already
have the full unix token in the current_user struct.
If so we should use the current_user unix token,
instead of doing a very complex user_in_group_sid()
which doesn't give reliable results anyway.

metze
(cherry picked from commit b79eff843be392f3065e912edca1434081d93c44)
(cherry picked from commit cb5c72c0a05a78ff1b86eb02cf5ecd3d7d69623d)

1 files changed, 18 insertions, 3 deletions

diff --git a/source/smbd/posix_acls.c b/source/smbd/posix_acls.c
index b538825b951..562776e798d 100644
--- a/source/smbd/posix_acls.c
+++ b/source/smbd/posix_acls.c
@@ -1119,16 +1119,31 @@ static bool uid_entry_in_group( canon_ace *uid_ace, canon_ace *group_ace )
 	if (sid_equal(&group_ace->trustee, &global_sid_World))
 		return True;
 
-	/* Assume that the current user is in the current group (force group) */
+	/*
+	 * if it's the current user, we already have the unix token
+	 * and don't need to do the complex user_in_group_sid() call
+	 */
+	if (uid_ace->unix_ug.uid == current_user.ut.uid) {
+		size_t i;
 
-	if (uid_ace->unix_ug.uid == current_user.ut.uid && group_ace->unix_ug.gid == current_user.ut.gid)
-		return True;
+		if (group_ace->unix_ug.gid == current_user.ut.gid) {
+			return True;
+		}
+
+		for (i=0; i < current_user.ut.ngroups; i++) {
+			if (group_ace->unix_ug.gid == current_user.ut.groups[i]) {
+				return True;
+			}
+		}
+	}
 
 	/* u_name talloc'ed off tos. */
 	u_name = uidtoname(uid_ace->unix_ug.uid);
 	if (!u_name) {
 		return False;
 	}
+
+	/* notice that this is not reliable for users exported by winbindd! */
 	return user_in_group_sid(u_name, &group_ace->trustee);
 }