/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Portions of this code from crypt_bsdmd5.so (bsdmd5.c) :
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 *
 * $FreeBSD: crypt.c,v 1.5 1996/10/14 08:34:02 phk Exp $
 *
 */

/*
 * Implements the specification from:
 *
 * From http://people.redhat.com/drepper/SHA-crypt.txt
 *
 * Portions of the code taken from inspired by or verified against the
 * source in the above document which is licensed as:
 *
 * "Released into the Public Domain by Ulrich Drepper <drepper@redhat.com>."
 */


#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <alloca.h>

#include <sha2.h>
#include <crypt.h>

#define MAX_SALT_LEN    16
#define ROUNDS_DEFAULT  5000
#define ROUNDS_MIN      1000
#define ROUNDS_MAX      999999999

#ifdef CRYPT_SHA256

#define DIGEST_CTX      SHA256_CTX
#define DIGESTInit      SHA256Init
#define DIGESTUpdate    SHA256Update
#define DIGESTFinal     SHA256Final
#define DIGEST_LEN      SHA256_DIGEST_LENGTH
#define MIXCHARS        32
static const char crypt_alg_magic[] = "$5";

#elif CRYPT_SHA512

#define DIGEST_CTX      SHA512_CTX
#define DIGESTInit      SHA512Init
#define DIGESTUpdate    SHA512Update
#define DIGESTFinal     SHA512Final
#define DIGEST_LEN      SHA512_DIGEST_LENGTH
#define MIXCHARS        64
static const char crypt_alg_magic[] = "$6";

#else
#error  "One of CRYPT_256 or CRYPT_512 must be defined"
#endif

static const int crypt_alg_magic_len = sizeof (crypt_alg_magic) - 1;


static uchar_t b64t[] =         /* 0 ... 63 => ascii - 64 */
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

#define b64_from_24bit(B2, B1, B0, N) \
{ \
        uint_t w = ((B2) << 16) | ((B1) << 8) | (B0); \
        int n = (N); \
        while (--n >= 0 && ctbufflen > 0) { \
                *p++ = b64t[w & 0x3f]; \
                w >>= 6; \
                ctbufflen--; \
        } \
}

static void
to64(char *s, uint64_t v, int n)
{
        while (--n >= 0) {
                *s++ = b64t[v & 0x3f];
                v >>= 6;
        }
}

#define ROUNDS          "rounds="
#define ROUNDSLEN       (sizeof (ROUNDS) - 1)

/*
 * get the integer value after rounds= where ever it occurs in the string.
 * if the last char after the int is a , or $ that is fine anything else is an
 * error.
 */
static uint32_t
getrounds(const char *s)
{
        char *r, *p, *e;
        long val;

        if (s == NULL)
                return (0);

        if ((r = strstr(s, ROUNDS)) == NULL) {
                return (0);
        }

        if (strncmp(r, ROUNDS, ROUNDSLEN) != 0) {
                return (0);
        }

        p = r + ROUNDSLEN;
        errno = 0;
        val = strtol(p, &e, 10);
        /*
         * An error occurred or there is non-numeric stuff at the end
         * which isn't one of the crypt(3c) special chars ',' or '$'
         */
        if (errno != 0 || val < 0 ||
            !(*e == '\0' || *e == ',' || *e == '$')) {
                return (0);
        }

        return ((uint32_t)val);
}


/* ARGSUSED4 */
char *
crypt_genhash_impl(char *ctbuffer,
            size_t ctbufflen,
            const char *plaintext,
            const char *switchsalt,
            const char **params)
{
        int salt_len, plaintext_len, i;
        char *salt;
        uchar_t A[DIGEST_LEN];
        uchar_t B[DIGEST_LEN];
        uchar_t DP[DIGEST_LEN];
        uchar_t DS[DIGEST_LEN];
        DIGEST_CTX ctxA, ctxB, ctxC, ctxDP, ctxDS;
        int rounds = ROUNDS_DEFAULT;
        int srounds = 0;
        boolean_t custom_rounds = B_FALSE;
        char *p;
        char *P, *Pp;
        char *S, *Sp;

        /* Refine the salt */
        salt = (char *)switchsalt;

        /* skip our magic string */
        if (strncmp((char *)salt, crypt_alg_magic, crypt_alg_magic_len) == 0) {
                salt += crypt_alg_magic_len + 1;
        }

        srounds = getrounds(salt);
        if (srounds != 0) {
                rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX));
                custom_rounds = B_TRUE;
                p = strchr(salt, '$');
                if (p != NULL)
                        salt = p + 1;
        }

        salt_len = MIN(strcspn(salt, "$"), MAX_SALT_LEN);
        plaintext_len = strlen(plaintext);

        /* 1. */
        DIGESTInit(&ctxA);

        /* 2. The password first, since that is what is most unknown */
        DIGESTUpdate(&ctxA, plaintext, plaintext_len);

        /* 3. Then the raw salt */
        DIGESTUpdate(&ctxA, salt, salt_len);

        /* 4. - 8. */
        DIGESTInit(&ctxB);
        DIGESTUpdate(&ctxB, plaintext, plaintext_len);
        DIGESTUpdate(&ctxB, salt, salt_len);
        DIGESTUpdate(&ctxB, plaintext, plaintext_len);
        DIGESTFinal(B, &ctxB);

        /* 9. - 10. */
        for (i = plaintext_len; i > MIXCHARS; i -= MIXCHARS)
                DIGESTUpdate(&ctxA, B, MIXCHARS);
        DIGESTUpdate(&ctxA, B, i);

        /* 11. */
        for (i = plaintext_len; i > 0; i >>= 1) {
                if ((i & 1) != 0) {
                        DIGESTUpdate(&ctxA, B, MIXCHARS);
                } else {
                        DIGESTUpdate(&ctxA, plaintext, plaintext_len);
                }
        }

        /* 12. */
        DIGESTFinal(A, &ctxA);

        /* 13. - 15. */
        DIGESTInit(&ctxDP);
        for (i = 0; i < plaintext_len; i++)
                DIGESTUpdate(&ctxDP, plaintext, plaintext_len);
        DIGESTFinal(DP, &ctxDP);

        /* 16. */
        Pp = P = alloca(plaintext_len);
        for (i = plaintext_len; i >= MIXCHARS; i -= MIXCHARS) {
                Pp = (char *)(memcpy(Pp, DP, MIXCHARS)) + MIXCHARS;
        }
        (void) memcpy(Pp, DP, i);

        /* 17. - 19. */
        DIGESTInit(&ctxDS);
        for (i = 0; i < 16 + (uint8_t)A[0]; i++)
                DIGESTUpdate(&ctxDS, salt, salt_len);
        DIGESTFinal(DS, &ctxDS);

        /* 20. */
        Sp = S = alloca(salt_len);
        for (i = salt_len; i >= MIXCHARS; i -= MIXCHARS) {
                Sp = (char *)(memcpy(Sp, DS, MIXCHARS)) + MIXCHARS;
        }
        (void) memcpy(Sp, DS, i);

        /*  21. */
        for (i = 0; i < rounds; i++) {
                DIGESTInit(&ctxC);

                if ((i & 1) != 0) {
                        DIGESTUpdate(&ctxC, P, plaintext_len);
                } else {
                        if (i == 0)
                                DIGESTUpdate(&ctxC, A, MIXCHARS);
                        else
                                DIGESTUpdate(&ctxC, DP, MIXCHARS);
                }

                if (i % 3 != 0) {
                        DIGESTUpdate(&ctxC, S, salt_len);
                }

                if (i % 7 != 0) {
                        DIGESTUpdate(&ctxC, P, plaintext_len);
                }

                if ((i & 1) != 0) {
                        if (i == 0)
                                DIGESTUpdate(&ctxC, A, MIXCHARS);
                        else
                                DIGESTUpdate(&ctxC, DP, MIXCHARS);
                } else {
                        DIGESTUpdate(&ctxC, P, plaintext_len);
                }
                DIGESTFinal(DP, &ctxC);
        }

        /* 22. Now make the output string */
        if (custom_rounds) {
                (void) snprintf(ctbuffer, ctbufflen,
                    "%s$rounds=%zu$", crypt_alg_magic, rounds);
        } else {
                (void) snprintf(ctbuffer, ctbufflen,
                    "%s$", crypt_alg_magic);
        }
        (void) strncat(ctbuffer, (const char *)salt, salt_len);
        (void) strlcat(ctbuffer, "$", ctbufflen);

        p = ctbuffer + strlen(ctbuffer);
        ctbufflen -= strlen(ctbuffer);

#ifdef CRYPT_SHA256
        b64_from_24bit(DP[ 0], DP[10], DP[20], 4);
        b64_from_24bit(DP[21], DP[ 1], DP[11], 4);
        b64_from_24bit(DP[12], DP[22], DP[ 2], 4);
        b64_from_24bit(DP[ 3], DP[13], DP[23], 4);
        b64_from_24bit(DP[24], DP[ 4], DP[14], 4);
        b64_from_24bit(DP[15], DP[25], DP[ 5], 4);
        b64_from_24bit(DP[ 6], DP[16], DP[26], 4);
        b64_from_24bit(DP[27], DP[ 7], DP[17], 4);
        b64_from_24bit(DP[18], DP[28], DP[ 8], 4);
        b64_from_24bit(DP[ 9], DP[19], DP[29], 4);
        b64_from_24bit(0, DP[31], DP[30], 3);
#elif CRYPT_SHA512
        b64_from_24bit(DP[ 0], DP[21], DP[42], 4);
        b64_from_24bit(DP[22], DP[43], DP[ 1], 4);
        b64_from_24bit(DP[44], DP[ 2], DP[23], 4);
        b64_from_24bit(DP[ 3], DP[24], DP[45], 4);
        b64_from_24bit(DP[25], DP[46], DP[ 4], 4);
        b64_from_24bit(DP[47], DP[ 5], DP[26], 4);
        b64_from_24bit(DP[ 6], DP[27], DP[48], 4);
        b64_from_24bit(DP[28], DP[49], DP[ 7], 4);
        b64_from_24bit(DP[50], DP[ 8], DP[29], 4);
        b64_from_24bit(DP[ 9], DP[30], DP[51], 4);
        b64_from_24bit(DP[31], DP[52], DP[10], 4);
        b64_from_24bit(DP[53], DP[11], DP[32], 4);
        b64_from_24bit(DP[12], DP[33], DP[54], 4);
        b64_from_24bit(DP[34], DP[55], DP[13], 4);
        b64_from_24bit(DP[56], DP[14], DP[35], 4);
        b64_from_24bit(DP[15], DP[36], DP[57], 4);
        b64_from_24bit(DP[37], DP[58], DP[16], 4);
        b64_from_24bit(DP[59], DP[17], DP[38], 4);
        b64_from_24bit(DP[18], DP[39], DP[60], 4);
        b64_from_24bit(DP[40], DP[61], DP[19], 4);
        b64_from_24bit(DP[62], DP[20], DP[41], 4);
        b64_from_24bit(0, 0, DP[63], 2);
#endif
        *p = '\0';

        (void) memset(A, 0, sizeof (A));
        (void) memset(B, 0, sizeof (B));
        (void) memset(DP, 0, sizeof (DP));
        (void) memset(DS, 0, sizeof (DS));

        return (ctbuffer);
}


/* ARGSUSED3 */
char *
crypt_gensalt_impl(char *gsbuffer,
            size_t gsbufflen,
            const char *oldsalt,
            const struct passwd *userinfo,
            const char **params)
{
        int fd;
        int err;
        ssize_t got;
        uint64_t rndval;
        uint32_t confrounds = 0;
        uint32_t saltrounds;
        char rndstr[sizeof (rndval) + 1];
        int i;

        for (i = 0; params != NULL && params[i] != NULL; i++) {
                if (strncmp(params[i], ROUNDS, ROUNDSLEN) == 0) {
                        confrounds = getrounds(params[i]);
                } else {
                        errno = EINVAL;
                        return (NULL);
                }
        }

        /*
         * If the config file has a higher value for rounds= than what
         * was in the old salt use that, otherwise keep what was in the
         * old salt.
         */
        saltrounds = getrounds(oldsalt);
        if (confrounds > saltrounds) {
                saltrounds = confrounds;
        }

        if ((fd = open("/dev/urandom", O_RDONLY)) == -1) {
                return (NULL);
        }

        got = read(fd, &rndval, sizeof (rndval));
        if (got < sizeof (rndval)) {
                err = errno;
                (void) close(fd);
                errno = err;
                return (NULL);
        }
        (void) close(fd);

        to64((char *)&rndstr, rndval, sizeof (rndval));
        rndstr[sizeof (rndstr) - 1] = 0;

        if (saltrounds > 0) {
                if (snprintf(gsbuffer, gsbufflen,
                    "%s$rounds=%d$",
                    crypt_alg_magic, saltrounds) >= gsbufflen)
                        goto fail;
        } else {
                if (snprintf(gsbuffer, gsbufflen,
                    "%s$", crypt_alg_magic) >= gsbufflen)
                        goto fail;
        }
        if (strlcat(gsbuffer, rndstr, gsbufflen) >= gsbufflen)
                goto fail;
        if (strlcat(gsbuffer, "$", gsbufflen) >= gsbufflen)
                goto fail;

        return (gsbuffer);

fail:
        (void) memset(gsbuffer, 0, gsbufflen);
        return (gsbuffer);
}