fixed a problem with getgroups() where it could include our current

effective gid which could mean that the user gets group 0 in their
group list for acl interpretation

this is a replacement fix for the one richard did in 2.2 (which didn't
cope wiith variable behaviour depending on which nss module was in
use)
(This used to be commit cfc5ca3416cea5ea5d2ac34f5521cb6367e42cd2)

source3/lib/util_sec.c

@@ -227,6 +227,7 @@ void set_effective_gid(gid_t gid)
 }
 
 static uid_t saved_euid, saved_ruid;
+static gid_t saved_egid, saved_rgid;
 
 /****************************************************************************
  save the real and effective uid for later restoration. Used by the quotas
@@ -264,6 +265,41 @@ void restore_re_uid(void)
 	assert_uid(saved_ruid, saved_euid);
 }
 
+
+/****************************************************************************
+ save the real and effective gid for later restoration. Used by the 
+ getgroups code
+****************************************************************************/
+void save_re_gid(void)
+{
+	saved_rgid = getgid();
+	saved_egid = getegid();
+}
+
+/****************************************************************************
+ and restore them!
+****************************************************************************/
+void restore_re_gid(void)
+{
+#if USE_SETRESUID
+	setresgid(saved_rgid, saved_egid, -1);
+#elif USE_SETREUID
+	setregid(saved_rgid, -1);
+	setregid(-1,saved_egid);
+#elif USE_SETUIDX
+	setgidx(ID_REAL, saved_rgid);
+	setgidx(ID_EFFECTIVE, saved_egid);
+#else
+	set_effective_gid(saved_egid);
+	if (getgid() != saved_rgid)
+		setgid(saved_rgid);
+	set_effective_gid(saved_egid);
+#endif
+
+	assert_gid(saved_rgid, saved_egid);
+}
+
+
 /****************************************************************************
  set the real AND effective uid to the current effective uid in a way that
  allows root to be regained.

source3/rpc_server/srv_pipe.c

@@ -435,7 +435,7 @@ failed authentication on named pipe %s.\n", domain, user_name, wks, p->name ));
 
 	/* Set up pipe user group membership. */
 	initialise_groups(p->pipe_user_name, p->pipe_user.uid, p->pipe_user.gid);
-	get_current_groups( &p->pipe_user.ngroups, &p->pipe_user.groups);
+	get_current_groups(p->pipe_user.gid, &p->pipe_user.ngroups, &p->pipe_user.groups);
 
 	if (server_info->ptok)
 		add_supplementary_nt_login_groups(&p->pipe_user.ngroups, &p->pipe_user.groups, &server_info->ptok);

source3/smbd/password.c

@@ -289,7 +289,7 @@ int register_vuid(auth_serversupplied_info *server_info, char *smb_name)
 	/* Find all the groups this uid is in and store them. 
 		Used by change_to_user() */
 	initialise_groups(vuser->user.unix_name, vuser->uid, vuser->gid);
-	get_current_groups( &vuser->n_groups, &vuser->groups);
+	get_current_groups(vuser->gid, &vuser->n_groups, &vuser->groups);
 
 	if (server_info->ptok)
 		add_supplementary_nt_login_groups(&vuser->n_groups, &vuser->groups, &server_info->ptok);

source3/smbd/sec_ctx.c

@@ -132,29 +132,39 @@ static void gain_root(void)
  Get the list of current groups.
 ****************************************************************************/
 
-int get_current_groups(int *p_ngroups, gid_t **p_groups)
+int get_current_groups(gid_t gid, int *p_ngroups, gid_t **p_groups)
 {
 	int i;
 	gid_t grp;
-	int ngroups = sys_getgroups(0,&grp);
+	int ngroups;
-	gid_t *groups;
+	gid_t *groups = NULL;
 
 	(*p_ngroups) = 0;
 	(*p_groups) = NULL;
 
-	if (ngroups <= 0)
+	/* this looks a little strange, but is needed to cope with
-		return -1;
+	   systems that put the current egid in the group list
+	   returned from getgroups() (tridge) */
+	save_re_gid();
+	set_effective_gid(gid);
+	setgid(gid);
 
-	if((groups = (gid_t *)malloc(sizeof(gid_t)*ngroups)) == NULL) {
+	ngroups = sys_getgroups(0,&grp);
+	if (ngroups <= 0) {
+		goto fail;
+	}
+
+	if((groups = (gid_t *)malloc(sizeof(gid_t)*(ngroups+1))) == NULL) {
 		DEBUG(0,("setup_groups malloc fail !\n"));
-		return -1;
+		goto fail;
 	}
 
 	if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
-		SAFE_FREE(groups);
+		goto fail;
-		return -1;
 	}
 
+	restore_re_gid();
+
 	(*p_ngroups) = ngroups;
 	(*p_groups) = groups;
 
@@ -164,7 +174,12 @@ int get_current_groups(int *p_ngroups, gid_t **p_groups)
 	}
 	DEBUG( 3, ( "\n" ) );
 
-    return ngroups;
+	return ngroups;
+
+fail:
+	SAFE_FREE(groups);
+	restore_re_gid();
+	return -1;
 }
 
 /****************************************************************************
@@ -204,7 +219,7 @@ BOOL initialise_groups(char *user, uid_t uid, gid_t gid)
 	SAFE_FREE(prev_ctx_p->groups);
 	prev_ctx_p->ngroups = 0;
 
-	get_current_groups(&prev_ctx_p->ngroups, &prev_ctx_p->groups);
+	get_current_groups(gid, &prev_ctx_p->ngroups, &prev_ctx_p->groups);
 
  done:
 	unbecome_root();
@@ -404,7 +419,7 @@ void init_sec_ctx(void)
 	ctx_p->uid = geteuid();
 	ctx_p->gid = getegid();
 
-	get_current_groups(&ctx_p->ngroups, &ctx_p->groups);
+	get_current_groups(ctx_p->gid, &ctx_p->ngroups, &ctx_p->groups);
 
 	ctx_p->token = NULL; /* Maps to guest user. */