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/* One way encryption based on SHA256 sum. | |
Copyright (C) 2007-2018 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@redhat.com>, 2007. | |
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 <assert.h> | |
#include <errno.h> | |
#include <stdbool.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <stdint.h> | |
#include <sys/param.h> | |
#include "sha256.h" | |
#include "crypt-private.h" | |
#ifdef USE_NSS | |
typedef int PRBool; | |
# include <hasht.h> | |
# include <nsslowhash.h> | |
# define sha256_init_ctx(ctxp, nss_ctxp) \ | |
do \ | |
{ \ | |
if (((nss_ctxp = NSSLOWHASH_NewContext (nss_ictx, HASH_AlgSHA256)) \ | |
== NULL)) \ | |
{ \ | |
if (nss_ctx != NULL) \ | |
NSSLOWHASH_Destroy (nss_ctx); \ | |
if (nss_alt_ctx != NULL) \ | |
NSSLOWHASH_Destroy (nss_alt_ctx); \ | |
return NULL; \ | |
} \ | |
NSSLOWHASH_Begin (nss_ctxp); \ | |
} \ | |
while (0) | |
# define sha256_process_bytes(buf, len, ctxp, nss_ctxp) \ | |
NSSLOWHASH_Update (nss_ctxp, (const unsigned char *) buf, len) | |
# define sha256_finish_ctx(ctxp, nss_ctxp, result) \ | |
do \ | |
{ \ | |
unsigned int ret; \ | |
NSSLOWHASH_End (nss_ctxp, result, &ret, sizeof (result)); \ | |
assert (ret == sizeof (result)); \ | |
NSSLOWHASH_Destroy (nss_ctxp); \ | |
nss_ctxp = NULL; \ | |
} \ | |
while (0) | |
#else | |
# define sha256_init_ctx(ctxp, nss_ctxp) \ | |
__sha256_init_ctx (ctxp) | |
# define sha256_process_bytes(buf, len, ctxp, nss_ctxp) \ | |
__sha256_process_bytes(buf, len, ctxp) | |
# define sha256_finish_ctx(ctxp, nss_ctxp, result) \ | |
__sha256_finish_ctx (ctxp, result) | |
#endif | |
/* Define our magic string to mark salt for SHA256 "encryption" | |
replacement. */ | |
static const char sha256_salt_prefix[] = "$5$"; | |
/* Prefix for optional rounds specification. */ | |
static const char sha256_rounds_prefix[] = "rounds="; | |
/* Maximum salt string length. */ | |
#define SALT_LEN_MAX 16 | |
/* Default number of rounds if not explicitly specified. */ | |
#define ROUNDS_DEFAULT 5000 | |
/* Minimum number of rounds. */ | |
#define ROUNDS_MIN 1000 | |
/* Maximum number of rounds. */ | |
#define ROUNDS_MAX 999999999 | |
/* Prototypes for local functions. */ | |
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); | |
char * | |
__sha256_crypt_r (const char *key, const char *salt, char *buffer, int buflen) | |
{ | |
unsigned char alt_result[32] | |
__attribute__ ((__aligned__ (__alignof__ (uint32_t)))); | |
unsigned char temp_result[32] | |
__attribute__ ((__aligned__ (__alignof__ (uint32_t)))); | |
size_t salt_len; | |
size_t key_len; | |
size_t cnt; | |
char *cp; | |
char *copied_key = NULL; | |
char *copied_salt = NULL; | |
char *p_bytes; | |
char *s_bytes; | |
/* Default number of rounds. */ | |
size_t rounds = ROUNDS_DEFAULT; | |
bool rounds_custom = false; | |
size_t alloca_used = 0; | |
char *free_key = NULL; | |
char *free_pbytes = NULL; | |
/* Find beginning of salt string. The prefix should normally always | |
be present. Just in case it is not. */ | |
if (strncmp (sha256_salt_prefix, salt, sizeof (sha256_salt_prefix) - 1) == 0) | |
/* Skip salt prefix. */ | |
salt += sizeof (sha256_salt_prefix) - 1; | |
if (strncmp (salt, sha256_rounds_prefix, sizeof (sha256_rounds_prefix) - 1) | |
== 0) | |
{ | |
const char *num = salt + sizeof (sha256_rounds_prefix) - 1; | |
char *endp; | |
unsigned long int srounds = strtoul (num, &endp, 10); | |
if (*endp == '$') | |
{ | |
salt = endp + 1; | |
rounds = MAX (ROUNDS_MIN, MIN (srounds, ROUNDS_MAX)); | |
rounds_custom = true; | |
} | |
} | |
salt_len = MIN (strcspn (salt, "$"), SALT_LEN_MAX); | |
key_len = strlen (key); | |
if ((key - (char *) 0) % __alignof__ (uint32_t) != 0) | |
{ | |
char *tmp; | |
if (__libc_use_alloca (alloca_used + key_len + __alignof__ (uint32_t))) | |
tmp = alloca_account (key_len + __alignof__ (uint32_t), alloca_used); | |
else | |
{ | |
free_key = tmp = (char *) malloc (key_len + __alignof__ (uint32_t)); | |
if (tmp == NULL) | |
return NULL; | |
} | |
key = copied_key = | |
memcpy (tmp + __alignof__ (uint32_t) | |
- (tmp - (char *) 0) % __alignof__ (uint32_t), | |
key, key_len); | |
assert ((key - (char *) 0) % __alignof__ (uint32_t) == 0); | |
} | |
if ((salt - (char *) 0) % __alignof__ (uint32_t) != 0) | |
{ | |
char *tmp = (char *) alloca (salt_len + __alignof__ (uint32_t)); | |
alloca_used += salt_len + __alignof__ (uint32_t); | |
salt = copied_salt = | |
memcpy (tmp + __alignof__ (uint32_t) | |
- (tmp - (char *) 0) % __alignof__ (uint32_t), | |
salt, salt_len); | |
assert ((salt - (char *) 0) % __alignof__ (uint32_t) == 0); | |
} | |
#ifdef USE_NSS | |
/* Initialize libfreebl3. */ | |
NSSLOWInitContext *nss_ictx = NSSLOW_Init (); | |
if (nss_ictx == NULL) | |
{ | |
free (free_key); | |
return NULL; | |
} | |
NSSLOWHASHContext *nss_ctx = NULL; | |
NSSLOWHASHContext *nss_alt_ctx = NULL; | |
#else | |
struct sha256_ctx ctx; | |
struct sha256_ctx alt_ctx; | |
#endif | |
/* Prepare for the real work. */ | |
sha256_init_ctx (&ctx, nss_ctx); | |
/* Add the key string. */ | |
sha256_process_bytes (key, key_len, &ctx, nss_ctx); | |
/* The last part is the salt string. This must be at most 16 | |
characters and it ends at the first `$' character. */ | |
sha256_process_bytes (salt, salt_len, &ctx, nss_ctx); | |
/* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The | |
final result will be added to the first context. */ | |
sha256_init_ctx (&alt_ctx, nss_alt_ctx); | |
/* Add key. */ | |
sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); | |
/* Add salt. */ | |
sha256_process_bytes (salt, salt_len, &alt_ctx, nss_alt_ctx); | |
/* Add key again. */ | |
sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); | |
/* Now get result of this (32 bytes) and add it to the other | |
context. */ | |
sha256_finish_ctx (&alt_ctx, nss_alt_ctx, alt_result); | |
/* Add for any character in the key one byte of the alternate sum. */ | |
for (cnt = key_len; cnt > 32; cnt -= 32) | |
sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); | |
sha256_process_bytes (alt_result, cnt, &ctx, nss_ctx); | |
/* Take the binary representation of the length of the key and for every | |
1 add the alternate sum, for every 0 the key. */ | |
for (cnt = key_len; cnt > 0; cnt >>= 1) | |
if ((cnt & 1) != 0) | |
sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); | |
else | |
sha256_process_bytes (key, key_len, &ctx, nss_ctx); | |
/* Create intermediate result. */ | |
sha256_finish_ctx (&ctx, nss_ctx, alt_result); | |
/* Start computation of P byte sequence. */ | |
sha256_init_ctx (&alt_ctx, nss_alt_ctx); | |
/* For every character in the password add the entire password. */ | |
for (cnt = 0; cnt < key_len; ++cnt) | |
sha256_process_bytes (key, key_len, &alt_ctx, nss_alt_ctx); | |
/* Finish the digest. */ | |
sha256_finish_ctx (&alt_ctx, nss_alt_ctx, temp_result); | |
/* Create byte sequence P. */ | |
if (__libc_use_alloca (alloca_used + key_len)) | |
cp = p_bytes = (char *) alloca (key_len); | |
else | |
{ | |
free_pbytes = cp = p_bytes = (char *)malloc (key_len); | |
if (free_pbytes == NULL) | |
{ | |
free (free_key); | |
return NULL; | |
} | |
} | |
for (cnt = key_len; cnt >= 32; cnt -= 32) | |
cp = mempcpy (cp, temp_result, 32); | |
memcpy (cp, temp_result, cnt); | |
/* Start computation of S byte sequence. */ | |
sha256_init_ctx (&alt_ctx, nss_alt_ctx); | |
/* For every character in the password add the entire password. */ | |
for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) | |
sha256_process_bytes (salt, salt_len, &alt_ctx, nss_alt_ctx); | |
/* Finish the digest. */ | |
sha256_finish_ctx (&alt_ctx, nss_alt_ctx, temp_result); | |
/* Create byte sequence S. */ | |
cp = s_bytes = alloca (salt_len); | |
for (cnt = salt_len; cnt >= 32; cnt -= 32) | |
cp = mempcpy (cp, temp_result, 32); | |
memcpy (cp, temp_result, cnt); | |
/* Repeatedly run the collected hash value through SHA256 to burn | |
CPU cycles. */ | |
for (cnt = 0; cnt < rounds; ++cnt) | |
{ | |
/* New context. */ | |
sha256_init_ctx (&ctx, nss_ctx); | |
/* Add key or last result. */ | |
if ((cnt & 1) != 0) | |
sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); | |
else | |
sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); | |
/* Add salt for numbers not divisible by 3. */ | |
if (cnt % 3 != 0) | |
sha256_process_bytes (s_bytes, salt_len, &ctx, nss_ctx); | |
/* Add key for numbers not divisible by 7. */ | |
if (cnt % 7 != 0) | |
sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); | |
/* Add key or last result. */ | |
if ((cnt & 1) != 0) | |
sha256_process_bytes (alt_result, 32, &ctx, nss_ctx); | |
else | |
sha256_process_bytes (p_bytes, key_len, &ctx, nss_ctx); | |
/* Create intermediate result. */ | |
sha256_finish_ctx (&ctx, nss_ctx, alt_result); | |
} | |
#ifdef USE_NSS | |
/* Free libfreebl3 resources. */ | |
NSSLOW_Shutdown (nss_ictx); | |
#endif | |
/* Now we can construct the result string. It consists of three | |
parts. */ | |
cp = __stpncpy (buffer, sha256_salt_prefix, MAX (0, buflen)); | |
buflen -= sizeof (sha256_salt_prefix) - 1; | |
if (rounds_custom) | |
{ | |
int n = __snprintf (cp, MAX (0, buflen), "%s%zu$", | |
sha256_rounds_prefix, rounds); | |
cp += n; | |
buflen -= n; | |
} | |
cp = __stpncpy (cp, salt, MIN ((size_t) MAX (0, buflen), salt_len)); | |
buflen -= MIN ((size_t) MAX (0, buflen), salt_len); | |
if (buflen > 0) | |
{ | |
*cp++ = '$'; | |
--buflen; | |
} | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[0], alt_result[10], alt_result[20], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[21], alt_result[1], alt_result[11], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[12], alt_result[22], alt_result[2], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[3], alt_result[13], alt_result[23], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[24], alt_result[4], alt_result[14], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[15], alt_result[25], alt_result[5], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[6], alt_result[16], alt_result[26], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[27], alt_result[7], alt_result[17], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[18], alt_result[28], alt_result[8], 4); | |
__b64_from_24bit (&cp, &buflen, | |
alt_result[9], alt_result[19], alt_result[29], 4); | |
__b64_from_24bit (&cp, &buflen, | |
0, alt_result[31], alt_result[30], 3); | |
if (buflen <= 0) | |
{ | |
__set_errno (ERANGE); | |
buffer = NULL; | |
} | |
else | |
*cp = '\0'; /* Terminate the string. */ | |
/* Clear the buffer for the intermediate result so that people | |
attaching to processes or reading core dumps cannot get any | |
information. We do it in this way to clear correct_words[] | |
inside the SHA256 implementation as well. */ | |
#ifndef USE_NSS | |
__sha256_init_ctx (&ctx); | |
__sha256_finish_ctx (&ctx, alt_result); | |
explicit_bzero (&ctx, sizeof (ctx)); | |
explicit_bzero (&alt_ctx, sizeof (alt_ctx)); | |
#endif | |
explicit_bzero (temp_result, sizeof (temp_result)); | |
explicit_bzero (p_bytes, key_len); | |
explicit_bzero (s_bytes, salt_len); | |
if (copied_key != NULL) | |
explicit_bzero (copied_key, key_len); | |
if (copied_salt != NULL) | |
explicit_bzero (copied_salt, salt_len); | |
free (free_key); | |
free (free_pbytes); | |
return buffer; | |
} | |
#ifndef _LIBC | |
# define libc_freeres_ptr(decl) decl | |
#endif | |
libc_freeres_ptr (static char *buffer); | |
/* This entry point is equivalent to the `crypt' function in Unix | |
libcs. */ | |
char * | |
__sha256_crypt (const char *key, const char *salt) | |
{ | |
/* We don't want to have an arbitrary limit in the size of the | |
password. We can compute an upper bound for the size of the | |
result in advance and so we can prepare the buffer we pass to | |
`sha256_crypt_r'. */ | |
static int buflen; | |
int needed = (sizeof (sha256_salt_prefix) - 1 | |
+ sizeof (sha256_rounds_prefix) + 9 + 1 | |
+ strlen (salt) + 1 + 43 + 1); | |
if (buflen < needed) | |
{ | |
char *new_buffer = (char *) realloc (buffer, needed); | |
if (new_buffer == NULL) | |
return NULL; | |
buffer = new_buffer; | |
buflen = needed; | |
} | |
return __sha256_crypt_r (key, salt, buffer, buflen); | |
} | |
#ifndef _LIBC | |
static void | |
__attribute__ ((__destructor__)) | |
free_mem (void) | |
{ | |
free (buffer); | |
} | |
#endif |