glibc/grp/initgroups.c

272 lines
7.2 KiB
C

/* Copyright (C) 1989,91,93,1996-1999,2000,01 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <alloca.h>
#include <errno.h>
#include <grp.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <nsswitch.h>
/* Type of the lookup function. */
typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
long int *, long int *,
gid_t **, long int, int *);
/* Prototype for the setgrent functions we use here. */
typedef enum nss_status (*set_function) (void);
/* Prototype for the endgrent functions we use here. */
typedef enum nss_status (*end_function) (void);
/* Prototype for the setgrent functions we use here. */
typedef enum nss_status (*get_function) (struct group *, char *,
size_t, int *);
/* The lookup function for the first entry of this service. */
extern int __nss_group_lookup (service_user **nip, const char *name,
void **fctp);
extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
extern service_user *__nss_group_database;
static enum nss_status
compat_call (service_user *nip, const char *user, gid_t group, long int *start,
long int *size, gid_t **groupsp, long int limit, int *errnop)
{
struct group grpbuf;
size_t buflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
char *tmpbuf;
enum nss_status status;
set_function setgrent_fct;
get_function getgrent_fct;
end_function endgrent_fct;
gid_t *groups = *groupsp;
getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
if (getgrent_fct == NULL)
return NSS_STATUS_UNAVAIL;
setgrent_fct = __nss_lookup_function (nip, "setgrent");
if (setgrent_fct)
{
status = DL_CALL_FCT (setgrent_fct, ());
if (status != NSS_STATUS_SUCCESS)
return status;
}
endgrent_fct = __nss_lookup_function (nip, "endgrent");
tmpbuf = __alloca (buflen);
do
{
while ((status = DL_CALL_FCT (getgrent_fct,
(&grpbuf, tmpbuf, buflen, errnop)),
status == NSS_STATUS_TRYAGAIN)
&& *errnop == ERANGE)
{
buflen *= 2;
tmpbuf = __alloca (buflen);
}
if (status != NSS_STATUS_SUCCESS)
goto done;
if (grpbuf.gr_gid != group)
{
char **m;
for (m = grpbuf.gr_mem; *m != NULL; ++m)
if (strcmp (*m, user) == 0)
{
/* Matches user. Insert this group. */
if (__builtin_expect (*start == *size, 0))
{
/* Need a bigger buffer. */
gid_t *newgroups;
long int newsize;
if (limit > 0 && *size == limit)
/* We reached the maximum. */
goto done;
if (limit <= 0)
newsize = 2 * *size;
else
newsize = MIN (limit, 2 * *size);
newgroups = realloc (groups, newsize * sizeof (*groups));
if (newgroups == NULL)
goto done;
*groupsp = groups = newgroups;
*size = newsize;
}
groups[*start] = grpbuf.gr_gid;
*start += 1;
break;
}
}
}
while (status == NSS_STATUS_SUCCESS);
done:
if (endgrent_fct)
DL_CALL_FCT (endgrent_fct, ());
return NSS_STATUS_SUCCESS;
}
static int
internal_getgrouplist (const char *user, gid_t group, long int *size,
gid_t **groupsp, long int limit)
{
service_user *nip = NULL;
initgroups_dyn_function fct;
enum nss_status status = NSS_STATUS_UNAVAIL;
int no_more;
/* Start is one, because we have the first group as parameter. */
long int start = 1;
*groupsp[0] = group;
if (__nss_group_database != NULL)
{
no_more = 0;
nip = __nss_group_database;
}
else
no_more = __nss_database_lookup ("group", NULL,
"compat [NOTFOUND=return] files", &nip);
while (! no_more)
{
fct = __nss_lookup_function (nip, "initgroups_dyn");
if (fct == NULL)
{
status = compat_call (nip, user, group, &start, size, groupsp,
limit, &errno);
if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
break;
}
else
status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
limit, &errno));
/* This is really only for debugging. */
if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
__libc_fatal ("illegal status in internal_getgrouplist");
if (status != NSS_STATUS_SUCCESS
&& nss_next_action (nip, status) == NSS_ACTION_RETURN)
break;
if (nip->next == NULL)
no_more = -1;
else
nip = nip->next;
}
return start;
}
/* Store at most *NGROUPS members of the group set for USER into
*GROUPS. Also include GROUP. The actual number of groups found is
returned in *NGROUPS. Return -1 if the if *NGROUPS is too small. */
int
getgrouplist (const char *user, gid_t group, gid_t *groups, int *ngroups)
{
gid_t *newgroups;
long int size = *ngroups;
int result;
newgroups = (gid_t *) malloc (size * sizeof (gid_t));
if (__builtin_expect (newgroups == NULL, 0))
/* No more memory. */
return -1;
result = internal_getgrouplist (user, group, &size, &newgroups, -1);
if (result > *ngroups)
{
*ngroups = result;
result = -1;
}
else
*ngroups = result;
memcpy (groups, newgroups, *ngroups * sizeof (gid_t));
free (newgroups);
return result;
}
/* Initialize the group set for the current user
by reading the group database and using all groups
of which USER is a member. Also include GROUP. */
int
initgroups (const char *user, gid_t group)
{
#if defined NGROUPS_MAX && NGROUPS_MAX == 0
/* No extra groups allowed. */
return 0;
#else
long int size;
gid_t *groups;
int ngroups;
int result;
/* We always use sysconf even if NGROUPS_MAX is defined. That way, the
limit can be raised in the kernel configuration without having to
recompile libc. */
long int limit = __sysconf (_SC_NGROUPS_MAX);
if (limit > 0)
size = limit;
else
{
/* No fixed limit on groups. Pick a starting buffer size. */
size = 16;
}
groups = (gid_t *) malloc (size * sizeof (gid_t));
if (__builtin_expect (groups == NULL, 0))
/* No more memory. */
return -1;
ngroups = internal_getgrouplist (user, group, &size, &groups, limit);
/* Try to set the maximum number of groups the kernel can handle. */
do
result = setgroups (ngroups, groups);
while (result == -1 && errno == EINVAL && --ngroups > 0);
free (groups);
return result;
#endif
}