Move tridge's getgrouplist() replacement function from replace.c to a new

'system_smbd.c' file, where it can link with become_root() and unbecome_root(),
and therefore avoiding some nasty 'it workes on linux' bugs.

(The replacement function is implemented in terms of initgroups(), which is
naturally only avaliable to root).

Andrew Bartlett
(This used to be commit a91018dd026be3db473bb1cf1f4981295f9758e4)

1 files changed, 105 insertions, 0 deletions

diff --git a/source3/lib/system_smbd.c b/source3/lib/system_smbd.c
new file mode 100644
index 0000000000..28ceaf3939
--- /dev/null
+++ b/source3/lib/system_smbd.c
@@ -0,0 +1,105 @@
+/* 
+   Unix SMB/CIFS implementation.
+   system call wrapper interface.
+   Copyright (C) Andrew Tridgell 2002
+   Copyright (C) Andrew Barteltt 2002
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/* 
+   This file may assume linkage with smbd - for things like become_root()
+   etc. 
+*/
+
+#include "includes.h"
+
+#ifndef HAVE_GETGROUPLIST
+/*
+  This is a *much* faster way of getting the list of groups for a user
+  without changing the current supplemenrary group list. The old
+  method used getgrent() which could take 20 minutes on a really big
+  network with hundeds of thousands of groups and users. The new method
+  takes a couple of seconds.
+
+  NOTE!! this function only works if it is called as root!
+  */
+static int getgrouplist_internals(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
+{
+	gid_t *gids_saved;
+	int ret, ngrp_saved;
+
+	/* work out how many groups we need to save */
+	ngrp_saved = getgroups(0, NULL);
+	if (ngrp_saved == -1) {
+		/* this shouldn't happen */
+		return -1;
+	}
+	
+	gids_saved = (gid_t *)malloc(sizeof(gid_t) * (ngrp_saved+1));
+	if (!gids_saved) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	ngrp_saved = getgroups(ngrp_saved, gids_saved);
+	if (ngrp_saved == -1) {
+		free(gids_saved);
+		/* very strange! */
+		return -1;
+	}
+
+	if (initgroups(user, gid) != 0) {
+		free(gids_saved);
+		return -1;
+	}
+
+	/* this must be done to cope with systems that put the current egid in the
+	   return from getgroups() */
+	save_re_gid();
+	set_effective_gid(gid);
+	setgid(gid);
+
+	ret = getgroups(*grpcnt, groups);
+	if (ret >= 0) {
+		*grpcnt = ret;
+	}
+
+	restore_re_gid();
+
+	if (setgroups(ngrp_saved, gids_saved) != 0) {
+		/* yikes! */
+		DEBUG(0,("ERROR: getgrouplist: failed to reset group list!\n"));
+		smb_panic("getgrouplist: failed to reset group list!\n");
+		free(gids_saved);
+		return -1;
+	}
+
+	free(gids_saved);
+	return ret;
+}
+#endif
+
+int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
+{
+#ifdef HAVE_GETGROUPLIST
+	return getgrouplist(user, gid, groups, grpcnt);
+#else
+	int retval;
+	become_root();
+	retval = getgrouplist_internals(user, gid, groups, grpcnt);
+	unbecome_root();
+#endif
+}