system_smbd.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   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

static int int_compare( int *a, int *b )
{
	if ( *a == *b )
		return 0;
	else if ( *a < *b )
		return -1;
	else
		return 1;
}

void remove_duplicate_gids( int *num_groups, gid_t *groups )
{
	int i;
	int count = *num_groups;

	if ( *num_groups <= 0 || !groups )
		return;

	DEBUG(8,("remove_duplicate_gids: Enter %d gids\n", *num_groups));

	qsort( groups, *num_groups, sizeof(gid_t), QSORT_CAST int_compare );

	for ( i=1; i<count; ) {
		if ( groups[i-1] == groups[i] ) {
			memmove( &groups[i-1], &groups[i], (count - i + 1)*sizeof(gid_t) );

			/* decrement the total number of groups and do not increment
			   the loop counter */
			count--;
			continue;
		}
		i++;
	}

	*num_groups = count;

	DEBUG(8,("remove_duplicate_gids: Exit %d gids\n", *num_groups));

	return;
}

/*
  This is a *much* faster way of getting the list of groups for a user
  without changing the current supplementary 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, num_gids;

	if (non_root_mode()) {
		*grpcnt = 0;
		return 0;
	}

	/* 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 = SMB_MALLOC_ARRAY(gid_t, ngrp_saved+1);
	if (!gids_saved) {
		errno = ENOMEM;
		return -1;
	}

	ngrp_saved = getgroups(ngrp_saved, gids_saved);
	if (ngrp_saved == -1) {
		SAFE_FREE(gids_saved);
		/* very strange! */
		return -1;
	}

	if (initgroups(user, gid) != 0) {
		DEBUG(0, ("getgrouplist_internals: initgroups() failed!\n"));
		SAFE_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);

	num_gids = getgroups(0, NULL);
	if (num_gids == -1) {
		SAFE_FREE(gids_saved);
		/* very strange! */
		return -1;
	}

	if (num_gids + 1 > *grpcnt) {
		*grpcnt = num_gids + 1;
		ret = -1;
	} else {
		ret = getgroups(*grpcnt - 1, &groups[1]);
		if (ret < 0) {
			SAFE_FREE(gids_saved);
			/* very strange! */
			return -1;
		}
		groups[0] = gid;
		*grpcnt = ret + 1;

		/* remove any duplicates gids in the list */
		remove_duplicate_gids( grpcnt, groups );
	}

	restore_re_gid();

	if (sys_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

static int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
{
	int retval;

	DEBUG(10,("sys_getgrouplist: user [%s]\n", user));
	
	/* see if we should disable winbindd lookups for local users */
	if (strchr(user, *lp_winbind_separator()) == NULL) {
		if ( !winbind_off() )
			DEBUG(0,("sys_getgroup_list: Insufficient environment space for %s\n",
				WINBINDD_DONT_ENV));
		else
			DEBUG(10,("sys_getgrouplist(): disabled winbindd for group lookup [user == %s]\n",
				user));
	}

#ifdef HAVE_GETGROUPLIST
	retval = getgrouplist(user, gid, groups, grpcnt);
#else
	become_root();
	retval = getgrouplist_internals(user, gid, groups, grpcnt);
	unbecome_root();
#endif

	/* allow winbindd lookups */
	winbind_on();
	
	return retval;
}

static BOOL getgroups_user(const char *user, gid_t primary_gid,
			   gid_t **ret_groups, size_t *p_ngroups)
{
	size_t ngrp;
	int max_grp;
	gid_t *temp_groups;
	gid_t *groups;
	int i;

	max_grp = groups_max();
	temp_groups = SMB_MALLOC_ARRAY(gid_t, max_grp);
	if (! temp_groups) {
		return False;
	}

	if (sys_getgrouplist(user, primary_gid, temp_groups, &max_grp) == -1) {
		gid_t *groups_tmp;

		groups_tmp = SMB_REALLOC_ARRAY(temp_groups, gid_t, max_grp);
		
		if (!groups_tmp) {
			SAFE_FREE(temp_groups);
			return False;
		}
		temp_groups = groups_tmp;
		
		if (sys_getgrouplist(user, primary_gid,
				     temp_groups, &max_grp) == -1) {
			DEBUG(0, ("get_user_groups: failed to get the unix "
				  "group list\n"));
			SAFE_FREE(temp_groups);
			return False;
		}
	}
	
	ngrp = 0;
	groups = NULL;

	/* Add in primary group first */
	add_gid_to_array_unique(NULL, primary_gid, &groups, &ngrp);

	for (i=0; i<max_grp; i++)
		add_gid_to_array_unique(NULL, temp_groups[i], &groups, &ngrp);

	*p_ngroups = ngrp;
	*ret_groups = groups;
	SAFE_FREE(temp_groups);
	return True;
}

NTSTATUS pdb_default_enum_group_memberships(struct pdb_methods *methods,
					    const char *username,
					    gid_t primary_gid,
					    DOM_SID **pp_sids,
					    gid_t **pp_gids,
					    size_t *p_num_groups)
{
	size_t i;

	if (!getgroups_user(username, primary_gid, pp_gids, p_num_groups)) {
		return NT_STATUS_NO_SUCH_USER;
	}

	if (*p_num_groups == 0) {
		smb_panic("primary group missing");
	}

	*pp_sids = SMB_MALLOC_ARRAY(DOM_SID, *p_num_groups);

	if (*pp_sids == NULL) {
		SAFE_FREE(pp_gids);
		return NT_STATUS_NO_MEMORY;
	}

	for (i=0; i<*p_num_groups; i++) {
		if (!NT_STATUS_IS_OK(gid_to_sid(&(*pp_sids)[i], (*pp_gids)[i]))) {
			DEBUG(1, ("get_user_groups: failed to convert "
				  "gid %ld to a sid!\n", 
				  (long int)(*pp_gids)[i+1]));
			SAFE_FREE(*pp_sids);
			SAFE_FREE(*pp_gids);
			return NT_STATUS_NO_SUCH_USER;
		}
	}

	return NT_STATUS_OK;
}