/* Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Thorsten Kukuk <kukuk@suse.de>, 1996.

   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

   <http://www.gnu.org/licenses/>.  */

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <grp.h>

#include <nss.h>

#include <nsswitch.h>

#include <stdio_ext.h>

#include <string.h>

#include <libc-lock.h>

#include <kernel-features.h>

static service_user *ni;

static enum nss_status (*nss_setgrent) (int stayopen);

static enum nss_status (*nss_getgrnam_r) (const char *name,

					  struct group * grp, char *buffer,

					  size_t buflen, int *errnop);

static enum nss_status (*nss_getgrgid_r) (gid_t gid, struct group * grp,

					  char *buffer, size_t buflen,

					  int *errnop);

static enum nss_status (*nss_getgrent_r) (struct group * grp, char *buffer,

					  size_t buflen, int *errnop);

static enum nss_status (*nss_endgrent) (void);

/* Get the declaration of the parser function.  */

#define ENTNAME grent

#define STRUCTURE group

#define EXTERN_PARSER

#include <nss/nss_files/files-parse.c>

/* Structure for remembering -group members ... */

#define BLACKLIST_INITIAL_SIZE 512

#define BLACKLIST_INCREMENT 256

struct blacklist_t

{

  char *data;

  int current;

  int size;

};

struct ent_t

{

  bool files;

  enum nss_status setent_status;

  FILE *stream;

  struct blacklist_t blacklist;

};

typedef struct ent_t ent_t;

static ent_t ext_ent = { true, NSS_STATUS_SUCCESS, NULL, { NULL, 0, 0 }};

/* Protect global state against multiple changers.  */

__libc_lock_define_initialized (static, lock)

/* Prototypes for local functions.  */

static void blacklist_store_name (const char *, ent_t *);

static bool in_blacklist (const char *, int, ent_t *);

/* Initialize the NSS interface/functions. The calling function must

   hold the lock.  */

static void

init_nss_interface (void)

{

  if (__nss_database_lookup2 ("group_compat", NULL, "nis", &ni) >= 0)

    {

      nss_setgrent = __nss_lookup_function (ni, "setgrent");

      nss_getgrnam_r = __nss_lookup_function (ni, "getgrnam_r");

      nss_getgrgid_r = __nss_lookup_function (ni, "getgrgid_r");

      nss_getgrent_r = __nss_lookup_function (ni, "getgrent_r");

      nss_endgrent = __nss_lookup_function (ni, "endgrent");

    }

}

static enum nss_status

internal_setgrent (ent_t *ent, int stayopen, int needent)

{

  enum nss_status status = NSS_STATUS_SUCCESS;

  ent->files = true;

  if (ent->blacklist.data != NULL)

    {

      ent->blacklist.current = 1;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

    }

  else

    ent->blacklist.current = 0;

  if (ent->stream == NULL)

    {

      ent->stream = fopen ("/etc/group", "rme");

      if (ent->stream == NULL)

	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;

      else

	/* We take care of locking ourself.  */

	__fsetlocking (ent->stream, FSETLOCKING_BYCALLER);

    }

  else

    rewind (ent->stream);

  if (needent && status == NSS_STATUS_SUCCESS && nss_setgrent)

    ent->setent_status = nss_setgrent (stayopen);

  return status;

}

enum nss_status

_nss_compat_setgrent (int stayopen)

{

  enum nss_status result;

  __libc_lock_lock (lock);

  if (ni == NULL)

    init_nss_interface ();

  result = internal_setgrent (&ext_ent, stayopen, 1);

  __libc_lock_unlock (lock);

  return result;

}

static enum nss_status

internal_endgrent (ent_t *ent)

{

  if (ent->stream != NULL)

    {

      fclose (ent->stream);

      ent->stream = NULL;

    }

  if (ent->blacklist.data != NULL)

    {

      ent->blacklist.current = 1;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

    }

  else

    ent->blacklist.current = 0;

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_endgrent (void)

{

  enum nss_status result;

  __libc_lock_lock (lock);

  if (nss_endgrent)

    nss_endgrent ();

  result = internal_endgrent (&ext_ent);

  __libc_lock_unlock (lock);

  return result;

}

/* get the next group from NSS  (+ entry) */

static enum nss_status

getgrent_next_nss (struct group *result, ent_t *ent, char *buffer,

		   size_t buflen, int *errnop)

{

  if (!nss_getgrent_r)

    return NSS_STATUS_UNAVAIL;

  /* If the setgrent call failed, say so.  */

  if (ent->setent_status != NSS_STATUS_SUCCESS)

    return ent->setent_status;

  do

    {

      enum nss_status status;

      if ((status = nss_getgrent_r (result, buffer, buflen, errnop)) !=

	  NSS_STATUS_SUCCESS)

	return status;

    }

  while (in_blacklist (result->gr_name, strlen (result->gr_name), ent));

  return NSS_STATUS_SUCCESS;

}

/* This function handle the +group entrys in /etc/group */

static enum nss_status

getgrnam_plusgroup (const char *name, struct group *result, ent_t *ent,

		    char *buffer, size_t buflen, int *errnop)

{

  if (!nss_getgrnam_r)

    return NSS_STATUS_UNAVAIL;

  enum nss_status status = nss_getgrnam_r (name, result, buffer, buflen,

					   errnop);

  if (status != NSS_STATUS_SUCCESS)

    return status;

  if (in_blacklist (result->gr_name, strlen (result->gr_name), ent))

    return NSS_STATUS_NOTFOUND;

  /* We found the entry.  */

  return NSS_STATUS_SUCCESS;

}

static enum nss_status

getgrent_next_file (struct group *result, ent_t *ent,

		    char *buffer, size_t buflen, int *errnop)

{

  struct parser_data *data = (void *) buffer;

  while (1)

    {

      fpos_t pos;

      int parse_res = 0;

      char *p;

      do

	{

	  /* We need at least 3 characters for one line.  */

	  if (__glibc_unlikely (buflen < 3))

	    {

	    erange:

	      *errnop = ERANGE;

	      return NSS_STATUS_TRYAGAIN;

	    }

	  fgetpos (ent->stream, &pos;;

	  buffer[buflen - 1] = '\xff';

	  p = fgets_unlocked (buffer, buflen, ent->stream);

	  if (p == NULL && feof_unlocked (ent->stream))

	    return NSS_STATUS_NOTFOUND;

	  if (p == NULL || __builtin_expect (buffer[buflen - 1] != '\xff', 0))

	    {

	    erange_reset:

	      fsetpos (ent->stream, &pos;;

	      goto erange;

	    }

	  /* Terminate the line for any case.  */

	  buffer[buflen - 1] = '\0';

	  /* Skip leading blanks.  */

	  while (isspace (*p))

	    ++p;

	}

      while (*p == '\0' || *p == '#' ||	/* Ignore empty and comment lines. */

	     /* Parse the line.  If it is invalid, loop to

	        get the next line of the file to parse.  */

	     !(parse_res = _nss_files_parse_grent (p, result, data, buflen,

						   errnop)));

      if (__glibc_unlikely (parse_res == -1))

	/* The parser ran out of space.  */

	goto erange_reset;

      if (result->gr_name[0] != '+' && result->gr_name[0] != '-')

	/* This is a real entry.  */

	break;

      /* -group */

      if (result->gr_name[0] == '-' && result->gr_name[1] != '\0'

	  && result->gr_name[1] != '@')

	{

	  blacklist_store_name (&result->gr_name[1], ent);

	  continue;

	}

      /* +group */

      if (result->gr_name[0] == '+' && result->gr_name[1] != '\0'

	  && result->gr_name[1] != '@')

	{

	  size_t len = strlen (result->gr_name);

	  char buf[len];

	  enum nss_status status;

	  /* Store the group in the blacklist for the "+" at the end of

	     /etc/group */

	  memcpy (buf, &result->gr_name[1], len);

	  status = getgrnam_plusgroup (&result->gr_name[1], result, ent,

				       buffer, buflen, errnop);

	  blacklist_store_name (buf, ent);

	  if (status == NSS_STATUS_SUCCESS)	/* We found the entry. */

	    break;

	  else if (status == NSS_STATUS_RETURN /* We couldn't parse the entry*/

		   || status == NSS_STATUS_NOTFOUND)	/* No group in NIS */

	    continue;

	  else

	    {

	      if (status == NSS_STATUS_TRYAGAIN)

		/* The parser ran out of space.  */

		goto erange_reset;

	      return status;

	    }

	}

      /* +:... */

      if (result->gr_name[0] == '+' && result->gr_name[1] == '\0')

	{

	  ent->files = false;

	  return getgrent_next_nss (result, ent, buffer, buflen, errnop);

	}

    }

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_getgrent_r (struct group *grp, char *buffer, size_t buflen,

			int *errnop)

{

  enum nss_status result = NSS_STATUS_SUCCESS;

  __libc_lock_lock (lock);

  /* Be prepared that the setgrent function was not called before.  */

  if (ni == NULL)

    init_nss_interface ();

  if (ext_ent.stream == NULL)

    result = internal_setgrent (&ext_ent, 1, 1);

  if (result == NSS_STATUS_SUCCESS)

    {

      if (ext_ent.files)

	result = getgrent_next_file (grp, &ext_ent, buffer, buflen, errnop);

      else

	result = getgrent_next_nss (grp, &ext_ent, buffer, buflen, errnop);

    }

  __libc_lock_unlock (lock);

  return result;

}

/* Searches in /etc/group and the NIS/NIS+ map for a special group */

static enum nss_status

internal_getgrnam_r (const char *name, struct group *result, ent_t *ent,

		     char *buffer, size_t buflen, int *errnop)

{

  struct parser_data *data = (void *) buffer;

  while (1)

    {

      fpos_t pos;

      int parse_res = 0;

      char *p;

      do

	{

	  /* We need at least 3 characters for one line.  */

	  if (__glibc_unlikely (buflen < 3))

	    {

	    erange:

	      *errnop = ERANGE;

	      return NSS_STATUS_TRYAGAIN;

	    }

	  fgetpos (ent->stream, &pos;;

	  buffer[buflen - 1] = '\xff';

	  p = fgets_unlocked (buffer, buflen, ent->stream);

	  if (p == NULL && feof_unlocked (ent->stream))

	    return NSS_STATUS_NOTFOUND;

	  if (p == NULL || __builtin_expect (buffer[buflen - 1] != '\xff', 0))

	    {

	    erange_reset:

	      fsetpos (ent->stream, &pos;;

	      goto erange;

	    }

	  /* Terminate the line for any case.  */

	  buffer[buflen - 1] = '\0';

	  /* Skip leading blanks.  */

	  while (isspace (*p))

	    ++p;

	}

      while (*p == '\0' || *p == '#' ||	/* Ignore empty and comment lines. */

	     /* Parse the line.  If it is invalid, loop to

	        get the next line of the file to parse.  */

	     !(parse_res = _nss_files_parse_grent (p, result, data, buflen,

						   errnop)));

      if (__glibc_unlikely (parse_res == -1))

	/* The parser ran out of space.  */

	goto erange_reset;

      /* This is a real entry.  */

      if (result->gr_name[0] != '+' && result->gr_name[0] != '-')

	{

	  if (strcmp (result->gr_name, name) == 0)

	    return NSS_STATUS_SUCCESS;

	  else

	    continue;

	}

      /* -group */

      if (result->gr_name[0] == '-' && result->gr_name[1] != '\0')

	{

	  if (strcmp (&result->gr_name[1], name) == 0)

	    return NSS_STATUS_NOTFOUND;

	  else

	    continue;

	}

      /* +group */

      if (result->gr_name[0] == '+' && result->gr_name[1] != '\0')

	{

	  if (strcmp (name, &result->gr_name[1]) == 0)

	    {

	      enum nss_status status;

	      status = getgrnam_plusgroup (name, result, ent,

					   buffer, buflen, errnop);

	      if (status == NSS_STATUS_RETURN)

		/* We couldn't parse the entry */

		continue;

	      else

		return status;

	    }

	}

      /* +:... */

      if (result->gr_name[0] == '+' && result->gr_name[1] == '\0')

	{

	  enum nss_status status;

	  status = getgrnam_plusgroup (name, result, ent,

				       buffer, buflen, errnop);

	  if (status == NSS_STATUS_RETURN)

	    /* We couldn't parse the entry */

	    continue;

	  else

	    return status;

	}

    }

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_getgrnam_r (const char *name, struct group *grp,

			char *buffer, size_t buflen, int *errnop)

{

  ent_t ent = { true, NSS_STATUS_SUCCESS, NULL, { NULL, 0, 0 }};

  enum nss_status result;

  if (name[0] == '-' || name[0] == '+')

    return NSS_STATUS_NOTFOUND;

  __libc_lock_lock (lock);

  if (ni == NULL)

    init_nss_interface ();

  __libc_lock_unlock (lock);

  result = internal_setgrent (&ent, 0, 0);

  if (result == NSS_STATUS_SUCCESS)

    result = internal_getgrnam_r (name, grp, &ent, buffer, buflen, errnop);

  internal_endgrent (&ent;;

  return result;

}

/* Searches in /etc/group and the NIS/NIS+ map for a special group id */

static enum nss_status

internal_getgrgid_r (gid_t gid, struct group *result, ent_t *ent,

		     char *buffer, size_t buflen, int *errnop)

{

  struct parser_data *data = (void *) buffer;

  while (1)

    {

      fpos_t pos;

      int parse_res = 0;

      char *p;

      do

	{

	  /* We need at least 3 characters for one line.  */

	  if (__glibc_unlikely (buflen < 3))

	    {

	    erange:

	      *errnop = ERANGE;

	      return NSS_STATUS_TRYAGAIN;

	    }

	  fgetpos (ent->stream, &pos;;

	  buffer[buflen - 1] = '\xff';

	  p = fgets_unlocked (buffer, buflen, ent->stream);

	  if (p == NULL && feof_unlocked (ent->stream))

	    return NSS_STATUS_NOTFOUND;

	  if (p == NULL || __builtin_expect (buffer[buflen - 1] != '\xff', 0))

	    {

	    erange_reset:

	      fsetpos (ent->stream, &pos;;

	      goto erange;

	    }

	  /* Terminate the line for any case.  */

	  buffer[buflen - 1] = '\0';

	  /* Skip leading blanks.  */

	  while (isspace (*p))

	    ++p;

	}

      while (*p == '\0' || *p == '#' ||	/* Ignore empty and comment lines. */

	     /* Parse the line.  If it is invalid, loop to

	        get the next line of the file to parse.  */

	     !(parse_res = _nss_files_parse_grent (p, result, data, buflen,

						   errnop)));

      if (__glibc_unlikely (parse_res == -1))

	/* The parser ran out of space.  */

	goto erange_reset;

      /* This is a real entry.  */

      if (result->gr_name[0] != '+' && result->gr_name[0] != '-')

	{

	  if (result->gr_gid == gid)

	    return NSS_STATUS_SUCCESS;

	  else

	    continue;

	}

      /* -group */

      if (result->gr_name[0] == '-' && result->gr_name[1] != '\0')

	{

	  blacklist_store_name (&result->gr_name[1], ent);

	  continue;

	}

      /* +group */

      if (result->gr_name[0] == '+' && result->gr_name[1] != '\0')

	{

	  /* Yes, no +1, see the memcpy call below.  */

	  size_t len = strlen (result->gr_name);

	  char buf[len];

	  enum nss_status status;

	  /* Store the group in the blacklist for the "+" at the end of

	     /etc/group */

	  memcpy (buf, &result->gr_name[1], len);

	  status = getgrnam_plusgroup (&result->gr_name[1], result, ent,

				       buffer, buflen, errnop);

	  blacklist_store_name (buf, ent);

	  if (status == NSS_STATUS_SUCCESS && result->gr_gid == gid)

	    break;

	  else

	    continue;

	}

      /* +:... */

      if (result->gr_name[0] == '+' && result->gr_name[1] == '\0')

	{

	  if (!nss_getgrgid_r)

	    return NSS_STATUS_UNAVAIL;

	  enum nss_status status = nss_getgrgid_r (gid, result, buffer, buflen,

						   errnop);

	  if (status == NSS_STATUS_RETURN) /* We couldn't parse the entry */

	    return NSS_STATUS_NOTFOUND;

	  else

	    return status;

	}

    }

  return NSS_STATUS_SUCCESS;

}

enum nss_status

_nss_compat_getgrgid_r (gid_t gid, struct group *grp,

			char *buffer, size_t buflen, int *errnop)

{

  ent_t ent = { true, NSS_STATUS_SUCCESS, NULL, { NULL, 0, 0 }};

  enum nss_status result;

  __libc_lock_lock (lock);

  if (ni == NULL)

    init_nss_interface ();

  __libc_lock_unlock (lock);

  result = internal_setgrent (&ent, 0, 0);

  if (result == NSS_STATUS_SUCCESS)

    result = internal_getgrgid_r (gid, grp, &ent, buffer, buflen, errnop);

  internal_endgrent (&ent;;

  return result;

}

/* Support routines for remembering -@netgroup and -user entries.

   The names are stored in a single string with `|' as separator. */

static void

blacklist_store_name (const char *name, ent_t *ent)

{

  int namelen = strlen (name);

  char *tmp;

  /* first call, setup cache */

  if (ent->blacklist.size == 0)

    {

      ent->blacklist.size = MAX (BLACKLIST_INITIAL_SIZE, 2 * namelen);

      ent->blacklist.data = malloc (ent->blacklist.size);

      if (ent->blacklist.data == NULL)

	return;

      ent->blacklist.data[0] = '|';

      ent->blacklist.data[1] = '\0';

      ent->blacklist.current = 1;

    }

  else

    {

      if (in_blacklist (name, namelen, ent))

	return;			/* no duplicates */

      if (ent->blacklist.current + namelen + 1 >= ent->blacklist.size)

	{

	  ent->blacklist.size += MAX (BLACKLIST_INCREMENT, 2 * namelen);

	  tmp = realloc (ent->blacklist.data, ent->blacklist.size);

	  if (tmp == NULL)

	    {

	      free (ent->blacklist.data);

	      ent->blacklist.size = 0;

	      return;

	    }

	  ent->blacklist.data = tmp;

	}

    }

  tmp = stpcpy (ent->blacklist.data + ent->blacklist.current, name);

  *tmp++ = '|';

  *tmp = '\0';

  ent->blacklist.current += namelen + 1;

  return;

}

/* Return whether ent->blacklist contains name.  */

static bool

in_blacklist (const char *name, int namelen, ent_t *ent)

{

  char buf[namelen + 3];

  char *cp;

  if (ent->blacklist.data == NULL)

    return false;

  buf[0] = '|';

  cp = stpcpy (&buf[1], name);

  *cp++ = '|';

  *cp = '\0';

  return strstr (ent->blacklist.data, buf) != NULL;

}