1 files changed, 218 insertions, 0 deletions
diff --git a/nss/initgroups.c b/nss/initgroups.c
new file mode 100644
index 0000000000..e803cecebc
--- /dev/null
+++ b/nss/initgroups.c
@@ -0,0 +1,218 @@
+/* Copyright (C) 1989, 1991-2023 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, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <grp.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <nsswitch.h>
+#include <scratch_buffer.h>
+#include <config.h>
+
+#include "../nscd/nscd-client.h"
+#include "../nscd/nscd_proto.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 *);
+
+static bool use_initgroups_entry;
+
+
+#include "initgroups-fallback.c"
+
+
+static int
+internal_getgrouplist (const char *user, gid_t group, long int *size,
+		       gid_t **groupsp, long int limit)
+{
+#ifdef USE_NSCD
+  if (__nss_not_use_nscd_group > 0
+      && ++__nss_not_use_nscd_group > NSS_NSCD_RETRY)
+    __nss_not_use_nscd_group = 0;
+  if (!__nss_not_use_nscd_group
+      && !__nss_database_custom[NSS_DBSIDX_group])
+    {
+      int n = __nscd_getgrouplist (user, group, size, groupsp, limit);
+      if (n >= 0)
+	return n;
+
+      /* nscd is not usable.  */
+      __nss_not_use_nscd_group = 1;
+    }
+#endif
+
+  enum nss_status status = NSS_STATUS_UNAVAIL;
+
+  /* Never store more than the starting *SIZE number of elements.  */
+  assert (*size > 0);
+  (*groupsp)[0] = group;
+  /* Start is one, because we have the first group as parameter.  */
+  long int start = 1;
+
+  nss_action_list nip;
+
+  if (__nss_database_get (nss_database_initgroups, &nip)
+      && nip != NULL)
+    {
+      use_initgroups_entry = true;
+    }
+  else if (__nss_database_get (nss_database_group, &nip)
+	   && nip != NULL)
+    {
+      use_initgroups_entry = false;
+    }
+  else
+    {
+      nip = __nss_action_parse ("files");
+      use_initgroups_entry = false;
+    }
+
+  while (nip && nip->module)
+    {
+      long int prev_start = start;
+
+      initgroups_dyn_function fct = __nss_lookup_function (nip,
+							   "initgroups_dyn");
+      if (fct == NULL)
+	status = compat_call (nip, user, group, &start, size, groupsp,
+			      limit, &errno);
+      else
+	status = DL_CALL_FCT (fct, (user, group, &start, size, groupsp,
+				    limit, &errno));
+
+      /* Remove duplicates.  */
+      long int cnt = prev_start;
+      while (cnt < start)
+	{
+	  long int inner;
+	  for (inner = 0; inner < prev_start; ++inner)
+	    if ((*groupsp)[inner] == (*groupsp)[cnt])
+	      break;
+
+	  if (inner < prev_start)
+	    (*groupsp)[cnt] = (*groupsp)[--start];
+	  else
+	    ++cnt;
+	}
+
+      /* This is really only for debugging.  */
+      if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
+	__libc_fatal ("Illegal status in internal_getgrouplist.\n");
+
+      /* For compatibility reason we will continue to look for more
+	 entries using the next service even though data has already
+	 been found if the nsswitch.conf file contained only a 'groups'
+	 line and no 'initgroups' line.  If the latter is available
+	 we always respect the status.  This means that the default
+	 for successful lookups is to return.  */
+      if ((use_initgroups_entry || status != NSS_STATUS_SUCCESS)
+	  && nss_next_action (nip, status) == NSS_ACTION_RETURN)
+	 break;
+
+      nip++;
+    }
+
+  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)
+{
+  long int size = MAX (1, *ngroups);
+
+  gid_t *newgroups = (gid_t *) malloc (size * sizeof (gid_t));
+  if (__glibc_unlikely (newgroups == NULL))
+    /* No more memory.  */
+    // XXX This is wrong.  The user provided memory, we have to use
+    // XXX it.  The internal functions must be called with the user
+    // XXX provided buffer and not try to increase the size if it is
+    // XXX too small.  For initgroups a flag could say: increase size.
+    return -1;
+
+  int total = internal_getgrouplist (user, group, &size, &newgroups, -1);
+
+  memcpy (groups, newgroups, MIN (*ngroups, total) * sizeof (gid_t));
+
+  free (newgroups);
+
+  int retval = total > *ngroups ? -1 : total;
+  *ngroups = total;
+
+  return retval;
+}
+
+nss_interface_function (getgrouplist)
+
+/* 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)
+    /* We limit the size of the initially allocated array.  */
+    size = MIN (limit, 64);
+  else
+    /* No fixed limit on groups.  Pick a starting buffer size.  */
+    size = 16;
+
+  groups = (gid_t *) malloc (size * sizeof (gid_t));
+  if (__glibc_unlikely (groups == NULL))
+    /* 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
+}
+
+nss_interface_function (initgroups)