glibc/crypt/crypt-entry.c

/*
 * UFC-crypt: ultra fast crypt(3) implementation
 *
 * Copyright (C) 1991-2021 Free Software Foundation, Inc.
 *
 * 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/>.
 *
 * crypt entry points
 *
 * @(#)crypt-entry.c	1.2 12/20/96
 *
 */

#ifdef DEBUG
#include <stdio.h>
#endif
#include <string.h>
#include <errno.h>
#include <fips-private.h>

#ifndef STATIC
#define STATIC static
#endif

#include "crypt-private.h"
#include <shlib-compat.h>

/* Prototypes for local functions.  */
#ifndef __GNU_LIBRARY__
void _ufc_clearmem (char *start, int cnt);
#else
#define _ufc_clearmem(start, cnt)   memset(start, 0, cnt)
#endif
extern char *__md5_crypt_r (const char *key, const char *salt, char *buffer,
			    int buflen);
extern char *__md5_crypt (const char *key, const char *salt);
extern char *__sha256_crypt_r (const char *key, const char *salt,
			       char *buffer, int buflen);
extern char *__sha256_crypt (const char *key, const char *salt);
extern char *__sha512_crypt_r (const char *key, const char *salt,
			       char *buffer, int buflen);
extern char *__sha512_crypt (const char *key, const char *salt);

/* Define our magic string to mark salt for MD5 encryption
   replacement.  This is meant to be the same as for other MD5 based
   encryption implementations.  */
static const char md5_salt_prefix[] = "$1$";

/* Magic string for SHA256 encryption.  */
static const char sha256_salt_prefix[] = "$5$";

/* Magic string for SHA512 encryption.  */
static const char sha512_salt_prefix[] = "$6$";

/* For use by the old, non-reentrant routines (crypt/encrypt/setkey)  */
extern struct crypt_data _ufc_foobar;

/*
 * UNIX crypt function
 */

char *
__crypt_r (const char *key, const char *salt,
	   struct crypt_data * __restrict data)
{
  ufc_long res[4];
  char ktab[9];
  ufc_long xx = 25; /* to cope with GCC long long compiler bugs */

#ifdef _LIBC
  /* Try to find out whether we have to use MD5 encryption replacement.  */
  if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0)
    {
      /* FIPS rules out MD5 password encryption.  */
      if (fips_enabled_p ())
	{
	  __set_errno (EPERM);
	  return NULL;
	}
      return __md5_crypt_r (key, salt, (char *) data,
			    sizeof (struct crypt_data));
    }

  /* Try to find out whether we have to use SHA256 encryption replacement.  */
  if (strncmp (sha256_salt_prefix, salt, sizeof (sha256_salt_prefix) - 1) == 0)
    return __sha256_crypt_r (key, salt, (char *) data,
			     sizeof (struct crypt_data));

  /* Try to find out whether we have to use SHA512 encryption replacement.  */
  if (strncmp (sha512_salt_prefix, salt, sizeof (sha512_salt_prefix) - 1) == 0)
    return __sha512_crypt_r (key, salt, (char *) data,
			     sizeof (struct crypt_data));
#endif

  /*
   * Hack DES tables according to salt
   */
  if (!_ufc_setup_salt_r (salt, data))
    {
      __set_errno (EINVAL);
      return NULL;
    }

  /* FIPS rules out DES password encryption.  */
  if (fips_enabled_p ())
    {
      __set_errno (EPERM);
      return NULL;
    }

  /*
   * Setup key schedule
   */
  _ufc_clearmem (ktab, (int) sizeof (ktab));
  (void) strncpy (ktab, key, 8);
  _ufc_mk_keytab_r (ktab, data);

  /*
   * Go for the 25 DES encryptions
   */
  _ufc_clearmem ((char*) res, (int) sizeof (res));
  _ufc_doit_r (xx,  data, &res[0]);

  /*
   * Do final permutations
   */
  _ufc_dofinalperm_r (res, data);

  /*
   * And convert back to 6 bit ASCII
   */
  _ufc_output_conversion_r (res[0], res[1], salt, data);

  /*
   * Erase key-dependent intermediate data.  Data dependent only on
   * the salt is not considered sensitive.
   */
  explicit_bzero (ktab, sizeof (ktab));
  explicit_bzero (data->keysched, sizeof (data->keysched));
  explicit_bzero (res, sizeof (res));

  return data->crypt_3_buf;
}
weak_alias (__crypt_r, crypt_r)

char *
crypt (const char *key, const char *salt)
{
#ifdef _LIBC
  /* Try to find out whether we have to use MD5 encryption replacement.  */
  if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0
      /* Let __crypt_r deal with the error code if FIPS is enabled.  */
      && !fips_enabled_p ())
    return __md5_crypt (key, salt);

  /* Try to find out whether we have to use SHA256 encryption replacement.  */
  if (strncmp (sha256_salt_prefix, salt, sizeof (sha256_salt_prefix) - 1) == 0)
    return __sha256_crypt (key, salt);

  /* Try to find out whether we have to use SHA512 encryption replacement.  */
  if (strncmp (sha512_salt_prefix, salt, sizeof (sha512_salt_prefix) - 1) == 0)
    return __sha512_crypt (key, salt);
#endif

  return __crypt_r (key, salt, &_ufc_foobar);
}

#if SHLIB_COMPAT (libcrypt, GLIBC_2_0, GLIBC_2_28)
weak_alias (crypt, fcrypt)
compat_symbol (libcrypt, fcrypt, fcrypt, GLIBC_2_0);
#endif