source: branches/samba-3.5.x/lib/uid_wrapper/uid_wrapper.c

/*
   Copyright (C) Andrew Tridgell 2009
 
   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 3 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, see <http://www.gnu.org/licenses/>.
 */

#define UID_WRAPPER_NOT_REPLACE
#include "includes.h"
#include "system/passwd.h"
#include "system/filesys.h"

#ifndef _PUBLIC_
#define _PUBLIC_
#endif

/*
  we keep the virtualised euid/egid/groups information here
 */
static struct {
        bool initialised;
        bool enabled;
        uid_t euid;
        gid_t egid;
        unsigned ngroups;
        gid_t *groups;
} uwrap;

static void uwrap_init(void)
{
        if (uwrap.initialised) return;
        uwrap.initialised = true;
        if (getenv("UID_WRAPPER")) {
                uwrap.enabled = true;
                /* put us in one group */
                uwrap.ngroups = 1;
                uwrap.groups = talloc_array(talloc_autofree_context(), gid_t, 1);
                uwrap.groups[0] = 0;
        }
}

#undef uwrap_enabled
_PUBLIC_ int uwrap_enabled(void)
{
        uwrap_init();
        return uwrap.enabled?1:0;
}

_PUBLIC_ int uwrap_seteuid(uid_t euid)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return seteuid(euid);
        }
        /* assume for now that the ruid stays as root */
        uwrap.euid = euid;
        return 0;
}

_PUBLIC_ uid_t uwrap_geteuid(void)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return geteuid();
        }
        return uwrap.euid;
}

_PUBLIC_ int uwrap_setegid(gid_t egid)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return setegid(egid);
        }
        /* assume for now that the ruid stays as root */
        uwrap.egid = egid;
        return 0;
}

_PUBLIC_ uid_t uwrap_getegid(void)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return getegid();
        }
        return uwrap.egid;
}

_PUBLIC_ int uwrap_setgroups(size_t size, const gid_t *list)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return setgroups(size, list);
        }

        talloc_free(uwrap.groups);
        uwrap.ngroups = 0;
        uwrap.groups = NULL;

        if (size != 0) {
                uwrap.groups = talloc_array(talloc_autofree_context(), gid_t, size);
                if (uwrap.groups == NULL) {
                        errno = ENOMEM;
                        return -1;
                }
                memcpy(uwrap.groups, list, size*sizeof(gid_t));
                uwrap.ngroups = size;
        }
        return 0;
}

_PUBLIC_ int uwrap_getgroups(int size, gid_t *list)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return getgroups(size, list);
        }

        if (size > uwrap.ngroups) {
                size = uwrap.ngroups;
        }
        if (size == 0) {
                return uwrap.ngroups;
        }
        if (size < uwrap.ngroups) {
                errno = EINVAL;
                return -1;
        }
        memcpy(list, uwrap.groups, size*sizeof(gid_t));
        return uwrap.ngroups;
}

_PUBLIC_ uid_t uwrap_getuid(void)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return getuid();
        }
        /* we don't simulate ruid changing */
        return 0;
}

_PUBLIC_ gid_t uwrap_getgid(void)
{
        uwrap_init();
        if (!uwrap.enabled) {
                return getgid();
        }
        /* we don't simulate rgid changing */
        return 0;
}