aboutsummaryrefslogtreecommitdiff
path: root/grp/initgroups.c
blob: 1f349d09ad5c292483566b2eb43d92c89deead7a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/* 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 " __FUNCTION__);

      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
}