From: Jeremy Allison <jra@samba.org>
Date: Fri, 18 Jan 2019 22:24:30 +0000 (-0800)
Subject: smbd: uid: Don't crash if 'force group' is added to an existing share connection.
X-Git-Tag: ldb-1.3.8~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83d82e735bb6399142b7e18cf83aa81abefeba33;p=thirdparty%2Fsamba.git

smbd: uid: Don't crash if 'force group' is added to an existing share connection.

smbd could crash if "force group" is added to a
share definition whilst an existing connection
to that share exists. In that case, don't change
the existing credentials for force group, only
do so for new connections.

Remove knownfail from regression test.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13690

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

Autobuild-User(master): Ralph Böhme <slow@samba.org>
Autobuild-Date(master): Fri Jan 25 16:31:27 CET 2019 on sn-devel-144

(cherry picked from commit e37f9956c1f2416408bad048a4618f6366086b6a)
---

diff --git a/selftest/knownfail b/selftest/knownfail
index 52b179a83c2..84776d4f35d 100644
--- a/selftest/knownfail
+++ b/selftest/knownfail
@@ -348,5 +348,3 @@
 # Disabling NTLM means you can't use samr to change the password
 ^samba.tests.ntlmdisabled.python\(ktest\).ntlmdisabled.NtlmDisabledTests.test_samr_change_password\(ktest\)
 ^samba.tests.ntlmdisabled.python\(ad_dc_no_ntlm\).ntlmdisabled.NtlmDisabledTests.test_ntlm_connection\(ad_dc_no_ntlm\)
-# BUG:https://bugzilla.samba.org/show_bug.cgi?id=13690
-^samba3.blackbox.force_group_change.*
diff --git a/source3/smbd/uid.c b/source3/smbd/uid.c
index b24ae3cc3b0..598327eba03 100644
--- a/source3/smbd/uid.c
+++ b/source3/smbd/uid.c
@@ -288,6 +288,7 @@ static bool change_to_user_internal(connection_struct *conn,
 	int snum;
 	gid_t gid;
 	uid_t uid;
+	const char *force_group_name;
 	char group_c;
 	int num_groups = 0;
 	gid_t *group_list = NULL;
@@ -314,9 +315,39 @@ static bool change_to_user_internal(connection_struct *conn,
 	 * See if we should force group for this service. If so this overrides
 	 * any group set in the force user code.
 	 */
-	if((group_c = *lp_force_group(talloc_tos(), snum))) {
+	force_group_name = lp_force_group(talloc_tos(), snum);
+	group_c = *force_group_name;
 
-		SMB_ASSERT(conn->force_group_gid != (gid_t)-1);
+	if ((group_c != '\0') && (conn->force_group_gid == (gid_t)-1)) {
+		/*
+		 * This can happen if "force group" is added to a
+		 * share definition whilst an existing connection
+		 * to that share exists. In that case, don't change
+		 * the existing credentials for force group, only
+		 * do so for new connections.
+		 *
+		 * BUG: https://bugzilla.samba.org/show_bug.cgi?id=13690
+		 */
+		DBG_INFO("Not forcing group %s on existing connection to "
+			"share %s for SMB user %s (unix user %s)\n",
+			force_group_name,
+			lp_const_servicename(snum),
+			session_info->unix_info->sanitized_username,
+			session_info->unix_info->unix_name);
+	}
+
+	if((group_c != '\0') && (conn->force_group_gid != (gid_t)-1)) {
+		/*
+		 * Only force group for connections where
+		 * conn->force_group_gid has already been set
+		 * to the correct value (i.e. the connection
+		 * happened after the 'force group' definition
+		 * was added to the share definition. Connections
+		 * that were made before force group was added
+		 * should stay with their existing credentials.
+		 *
+		 * BUG: https://bugzilla.samba.org/show_bug.cgi?id=13690
+		 */
 
 		if (group_c == '+') {
 			int i;