From e65c65fc710fa030bfb8319efc43fcdc9ce5a26f Mon Sep 17 00:00:00 2001 From: Sumit Bose Date: Fri, 27 Feb 2009 20:32:31 +0100 Subject: first version of LOCAL pam backend --- server/util/nss_sha512crypt.c | 419 ++++++++++++++++++++++++++++++++++++++++++ server/util/nss_sha512crypt.h | 3 + 2 files changed, 422 insertions(+) create mode 100644 server/util/nss_sha512crypt.c create mode 100644 server/util/nss_sha512crypt.h (limited to 'server/util') diff --git a/server/util/nss_sha512crypt.c b/server/util/nss_sha512crypt.c new file mode 100644 index 00000000..84cb61c2 --- /dev/null +++ b/server/util/nss_sha512crypt.c @@ -0,0 +1,419 @@ +/* This file is based on the work of Ulrich Drepper + * (http://people.redhat.com/drepper/SHA-crypt.txt). I have replaced the + * included SHA512 implementation by calls to NSS + * (http://www.mozilla.org/projects/security/pki/nss/). + * + * Sumit Bose + */ +/* SHA512-based Unix crypt implementation. + Released into the Public Domain by Ulrich Drepper . */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include + + +static int nspr_nss_init_done = 0; + +/* according to + * http://www.mozilla.org/projects/security/pki/nss/ref/ssl/sslfnc.html#1234224 + * PR_Init must be called, but at least for the HASH_* calls it seems to work + * quite well without. */ +static int nspr_nss_init(void) +{ + int ret; + PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 0); + ret = NSS_NoDB_Init(NULL); + if (ret != SECSuccess) { + return ret; + } + nspr_nss_init_done = 1; + return 0; +} + +/* added for completness, so far not used */ +static int nspr_nss_cleanup(void) +{ + int ret; + ret=NSS_Shutdown(); + if (ret != SECSuccess ) { + return ret; + } + PR_Cleanup(); + nspr_nss_init_done = 0; + return 0; +} + +/* Define our magic string to mark salt for SHA512 "encryption" + replacement. */ +static const char sha512_salt_prefix[] = "$6$"; + +/* Prefix for optional rounds specification. */ +static const char sha512_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 + +/* Table with characters for base64 transformation. */ +static const char b64t[64] = +"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; + + +static char * +sha512_crypt_r (const char *key, const char *salt, char *buffer, int buflen) +{ + unsigned char alt_result[64] + __attribute__ ((__aligned__ (__alignof__ (uint64_t)))); + unsigned char temp_result[64] + __attribute__ ((__aligned__ (__alignof__ (uint64_t)))); + HASHContext *ctx; + HASHContext *alt_ctx; + 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; + + int ret; + unsigned int part; + + /* Find beginning of salt string. The prefix should normally always + be present. Just in case it is not. */ + if (strncmp (sha512_salt_prefix, salt, sizeof (sha512_salt_prefix) - 1) == 0) + /* Skip salt prefix. */ + salt += sizeof (sha512_salt_prefix) - 1; + + if (strncmp (salt, sha512_rounds_prefix, sizeof (sha512_rounds_prefix) - 1) + == 0) + { + const char *num = salt + sizeof (sha512_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__ (uint64_t) != 0) + { + char *tmp = (char *) alloca (key_len + __alignof__ (uint64_t)); + key = copied_key = + memcpy (tmp + __alignof__ (uint64_t) + - (tmp - (char *) 0) % __alignof__ (uint64_t), + key, key_len); + } + + if ((salt - (char *) 0) % __alignof__ (uint64_t) != 0) + { + char *tmp = (char *) alloca (salt_len + __alignof__ (uint64_t)); + salt = copied_salt = + memcpy (tmp + __alignof__ (uint64_t) + - (tmp - (char *) 0) % __alignof__ (uint64_t), + salt, salt_len); + } + + + if (!nspr_nss_init_done) { + ret = nspr_nss_init(); + if (ret != SECSuccess) return NULL; + } + + ctx = HASH_Create(HASH_AlgSHA512); + if ( ctx == NULL ) { + return NULL; + } + + alt_ctx = HASH_Create(HASH_AlgSHA512); + if ( alt_ctx == NULL ) { + return NULL; + } + + + /* Prepare for the real work. */ + HASH_Begin(ctx); + + /* Add the key string. */ + HASH_Update(ctx, key, key_len); + + /* The last part is the salt string. This must be at most 16 + characters and it ends at the first `$' character (for + compatibility with existing implementations). */ + HASH_Update(ctx, salt, salt_len); + + + /* Compute alternate SHA512 sum with input KEY, SALT, and KEY. The + final result will be added to the first context. */ + HASH_Begin(alt_ctx); + + /* Add key. */ + HASH_Update(alt_ctx, key, key_len); + + /* Add salt. */ + HASH_Update(alt_ctx, salt, salt_len); + + /* Add key again. */ + HASH_Update(alt_ctx, key, key_len); + + /* Now get result of this (64 bytes) and add it to the other + context. */ + HASH_End(alt_ctx, alt_result, &part, HASH_ResultLenContext(alt_ctx)); + + /* Add for any character in the key one byte of the alternate sum. */ + for (cnt = key_len; cnt > 64; cnt -= 64) { + HASH_Update(ctx, alt_result, 64); + } + HASH_Update(ctx, alt_result, cnt); + + /* 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) { + HASH_Update(ctx, alt_result, 64); + } else { + HASH_Update(ctx, key, key_len); + } + + /* Create intermediate result. */ + HASH_End(ctx, alt_result, &part, HASH_ResultLenContext(ctx)); + + /* Start computation of P byte sequence. */ + HASH_Begin(alt_ctx); + + /* For every character in the password add the entire password. */ + for (cnt = 0; cnt < key_len; ++cnt) { + HASH_Update(alt_ctx, key, key_len); + } + + /* Finish the digest. */ + HASH_End(alt_ctx, temp_result, &part, HASH_ResultLenContext(alt_ctx)); + + /* Create byte sequence P. */ + cp = p_bytes = alloca (key_len); + for (cnt = key_len; cnt >= 64; cnt -= 64) + cp = mempcpy (cp, temp_result, 64); + memcpy (cp, temp_result, cnt); + + /* Start computation of S byte sequence. */ + HASH_Begin(alt_ctx); + + /* For every character in the password add the entire password. */ + for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt) { + HASH_Update(alt_ctx, salt, salt_len); + } + + /* Finish the digest. */ + HASH_End(alt_ctx, temp_result, &part, HASH_ResultLenContext(alt_ctx)); + + /* Create byte sequence S. */ + cp = s_bytes = alloca (salt_len); + for (cnt = salt_len; cnt >= 64; cnt -= 64) + cp = mempcpy (cp, temp_result, 64); + memcpy (cp, temp_result, cnt); + + /* Repeatedly run the collected hash value through SHA512 to burn + CPU cycles. */ + for (cnt = 0; cnt < rounds; ++cnt) + { + /* New context. */ + HASH_Begin(ctx); + + /* Add key or last result. */ + if ((cnt & 1) != 0) { + HASH_Update(ctx, p_bytes, key_len); + } else { + HASH_Update(ctx, alt_result, 64); + } + + /* Add salt for numbers not divisible by 3. */ + if (cnt % 3 != 0) { + HASH_Update(ctx, s_bytes, salt_len); + } + + /* Add key for numbers not divisible by 7. */ + if (cnt % 7 != 0) { + HASH_Update(ctx, p_bytes, key_len); + } + + /* Add key or last result. */ + if ((cnt & 1) != 0) { + HASH_Update(ctx, alt_result, 64); + } else { + HASH_Update(ctx, p_bytes, key_len); + } + + /* Create intermediate result. */ + HASH_End(ctx, alt_result, &part, HASH_ResultLenContext(ctx)); + } + + /* Now we can construct the result string. It consists of three + parts. */ + cp = __stpncpy (buffer, sha512_salt_prefix, MAX (0, buflen)); + buflen -= sizeof (sha512_salt_prefix) - 1; + + if (rounds_custom) + { + int n = snprintf (cp, MAX (0, buflen), "%s%zu$", + sha512_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; + } + +#define b64_from_24bit(B2, B1, B0, N) \ + do { \ + unsigned int w = ((B2) << 16) | ((B1) << 8) | (B0); \ + int n = (N); \ + while (n-- > 0 && buflen > 0) \ + { \ + *cp++ = b64t[w & 0x3f]; \ + --buflen; \ + w >>= 6; \ + } \ + } while (0) + + b64_from_24bit (alt_result[0], alt_result[21], alt_result[42], 4); + b64_from_24bit (alt_result[22], alt_result[43], alt_result[1], 4); + b64_from_24bit (alt_result[44], alt_result[2], alt_result[23], 4); + b64_from_24bit (alt_result[3], alt_result[24], alt_result[45], 4); + b64_from_24bit (alt_result[25], alt_result[46], alt_result[4], 4); + b64_from_24bit (alt_result[47], alt_result[5], alt_result[26], 4); + b64_from_24bit (alt_result[6], alt_result[27], alt_result[48], 4); + b64_from_24bit (alt_result[28], alt_result[49], alt_result[7], 4); + b64_from_24bit (alt_result[50], alt_result[8], alt_result[29], 4); + b64_from_24bit (alt_result[9], alt_result[30], alt_result[51], 4); + b64_from_24bit (alt_result[31], alt_result[52], alt_result[10], 4); + b64_from_24bit (alt_result[53], alt_result[11], alt_result[32], 4); + b64_from_24bit (alt_result[12], alt_result[33], alt_result[54], 4); + b64_from_24bit (alt_result[34], alt_result[55], alt_result[13], 4); + b64_from_24bit (alt_result[56], alt_result[14], alt_result[35], 4); + b64_from_24bit (alt_result[15], alt_result[36], alt_result[57], 4); + b64_from_24bit (alt_result[37], alt_result[58], alt_result[16], 4); + b64_from_24bit (alt_result[59], alt_result[17], alt_result[38], 4); + b64_from_24bit (alt_result[18], alt_result[39], alt_result[60], 4); + b64_from_24bit (alt_result[40], alt_result[61], alt_result[19], 4); + b64_from_24bit (alt_result[62], alt_result[20], alt_result[41], 4); + b64_from_24bit (0, 0, alt_result[63], 2); + + if (buflen <= 0) + { + 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 SHA512 implementation as well. */ + HASH_Destroy(ctx); + HASH_Destroy(alt_ctx); + + memset (temp_result, '\0', sizeof (temp_result)); + memset (p_bytes, '\0', key_len); + memset (s_bytes, '\0', salt_len); + memset (&ctx, '\0', sizeof (ctx)); + memset (&alt_ctx, '\0', sizeof (alt_ctx)); + if (copied_key != NULL) + memset (copied_key, '\0', key_len); + if (copied_salt != NULL) + memset (copied_salt, '\0', salt_len); + + return buffer; +} + + +/* This entry point is equivalent to the `crypt' function in Unix + libcs. */ +char * +nss_sha512_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 + `sha512_crypt_r'. */ + static char *buffer; + static int buflen; + int needed = (sizeof (sha512_salt_prefix) - 1 + + sizeof (sha512_rounds_prefix) + 9 + 1 + + strlen (salt) + 1 + 86 + 1); + + if (buflen < needed) + { + char *new_buffer = (char *) realloc (buffer, needed); + if (new_buffer == NULL) + return NULL; + + buffer = new_buffer; + buflen = needed; + } + + return sha512_crypt_r (key, salt, buffer, buflen); +} + +char *gen_salt(void) +{ + int ret; + unsigned char bin_rand[12]; + static char b64_rand[17]; + char *cp; + int buflen; + + if (!nspr_nss_init_done) { + ret = nspr_nss_init(); + if (ret != SECSuccess) return NULL; + } + + ret = PK11_GenerateRandom(bin_rand, sizeof(bin_rand)-1); + cp = b64_rand; + buflen = 16; + b64_from_24bit (bin_rand[0], bin_rand[1], bin_rand[2], 4); + b64_from_24bit (bin_rand[3], bin_rand[4], bin_rand[5], 4); + b64_from_24bit (bin_rand[6], bin_rand[7], bin_rand[8], 4); + b64_from_24bit (bin_rand[9], bin_rand[10], bin_rand[11], 4); + + *cp++ = '\0'; + + return b64_rand; + +} + diff --git a/server/util/nss_sha512crypt.h b/server/util/nss_sha512crypt.h new file mode 100644 index 00000000..0d063217 --- /dev/null +++ b/server/util/nss_sha512crypt.h @@ -0,0 +1,3 @@ + +char * nss_sha512_crypt (const char *key, const char *salt); +char *gen_salt(void); -- cgit