/*      $OpenBSD: softraid.c,v 1.7 2024/04/25 18:31:49 kn Exp $ */

/*
 * Copyright (c) 2012 Joel Sing <jsing@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/queue.h>

#include <dev/biovar.h>
#include <dev/softraidvar.h>

#include <lib/libsa/bcrypt_pbkdf.h>
#include <lib/libsa/hmac_sha1.h>
#include <lib/libsa/pkcs5_pbkdf2.h>
#include <lib/libsa/rijndael.h>

#include "stand.h"
#include "softraid.h"

#define RIJNDAEL128_BLOCK_LEN     16
#define PASSPHRASE_LENGTH 1024

#define SR_CRYPTO_KEYBLOCK_BYTES SR_CRYPTO_MAXKEYS * SR_CRYPTO_KEYBYTES

/* List of softraid volumes. */
struct sr_boot_volume_head sr_volumes;

/* List of softraid keydisks. */
struct sr_boot_keydisk_head sr_keydisks;

#ifdef DEBUG
void
printhex(const char *s, const u_int8_t *buf, size_t len)
{
        u_int8_t n1, n2;
        size_t i;

        printf("%s: ", s);
        for (i = 0; i < len; i++) {
                n1 = buf[i] & 0x0f;
                n2 = buf[i] >> 4;
                printf("%c", n2 > 9 ? n2 + 'a' - 10 : n2 + '0');
                printf("%c", n1 > 9 ? n1 + 'a' - 10 : n1 + '0');
        }
        printf("\n");
}
#endif

void
sr_clear_keys(void)
{
        struct sr_boot_volume *bv;
        struct sr_boot_keydisk *kd, *nkd;

        SLIST_FOREACH(bv, &sr_volumes, sbv_link) {
                if (bv->sbv_level != 'C' && bv->sbv_level != 0x1C)
                        continue;
                if (bv->sbv_keys != NULL) {
                        explicit_bzero(bv->sbv_keys, SR_CRYPTO_KEYBLOCK_BYTES);
                        free(bv->sbv_keys, SR_CRYPTO_KEYBLOCK_BYTES);
                        bv->sbv_keys = NULL;
                }
                if (bv->sbv_maskkey != NULL) {
                        explicit_bzero(bv->sbv_maskkey, SR_CRYPTO_MAXKEYBYTES);
                        free(bv->sbv_maskkey, SR_CRYPTO_MAXKEYBYTES);
                        bv->sbv_maskkey = NULL;
                }
        }
        SLIST_FOREACH_SAFE(kd, &sr_keydisks, kd_link, nkd) {
                explicit_bzero(kd, sizeof(*kd));
                free(kd, sizeof(*kd));
        }
}

void
sr_crypto_calculate_check_hmac_sha1(u_int8_t *maskkey, int maskkey_size,
    u_int8_t *key, int key_size, u_char *check_digest)
{
        u_int8_t check_key[SHA1_DIGEST_LENGTH];
        SHA1_CTX shactx;

        explicit_bzero(check_key, sizeof(check_key));
        explicit_bzero(&shactx, sizeof(shactx));

        /* k = SHA1(mask_key) */
        SHA1Init(&shactx);
        SHA1Update(&shactx, maskkey, maskkey_size);
        SHA1Final(check_key, &shactx);

        /* mac = HMAC_SHA1_k(unencrypted key) */
        hmac_sha1(key, key_size, check_key, sizeof(check_key), check_digest);

        explicit_bzero(check_key, sizeof(check_key));
        explicit_bzero(&shactx, sizeof(shactx));
}

static int
sr_crypto_decrypt_keys(struct sr_meta_crypto *cm,
    struct sr_crypto_kdfinfo *kdfinfo, u_int8_t *kp)
{
        u_int8_t digest[SHA1_DIGEST_LENGTH];
        rijndael_ctx ctx;
        u_int8_t *cp;
        int rv = -1;
        int i;

        if (rijndael_set_key(&ctx, kdfinfo->maskkey, 256) != 0)
                goto done;

        cp = (u_int8_t *)cm->scm_key;
        for (i = 0; i < SR_CRYPTO_KEYBLOCK_BYTES; i += RIJNDAEL128_BLOCK_LEN)
                rijndael_decrypt(&ctx, (u_char *)(cp + i), (u_char *)(kp + i));

        /* Check that the key decrypted properly. */
        sr_crypto_calculate_check_hmac_sha1(kdfinfo->maskkey,
            sizeof(kdfinfo->maskkey), kp, SR_CRYPTO_KEYBLOCK_BYTES, digest);

        if (bcmp(digest, cm->chk_hmac_sha1.sch_mac, sizeof(digest)) == 0)
                rv = 0;

 done:
        explicit_bzero(digest, sizeof(digest));

        return rv;
}

static int
sr_crypto_passphrase_decrypt(struct sr_meta_crypto *cm,
    struct sr_crypto_kdfinfo *kdfinfo, u_int8_t *kp)
{
        char passphrase[PASSPHRASE_LENGTH];
        struct sr_crypto_pbkdf *kdfhint;
        int rv = -1;
        int c, i;

        kdfhint = (struct sr_crypto_pbkdf *)&cm->scm_kdfhint;

        for (;;) {
                printf("Passphrase: ");
#ifdef IDLE_POWEROFF
extern int idle_poweroff(void);
                idle_poweroff();
#endif /* IDLE_POWEROFF */
                for (i = 0; i < PASSPHRASE_LENGTH - 1; i++) {
                        c = cngetc();
                        if (c == '\r' || c == '\n') {
                                break;
                        } else if (c == '\b') {
                                i = i > 0 ? i - 2 : -1;
                                continue;
                        }
                        passphrase[i] = (c & 0xff);
                }
                passphrase[i] = 0;
                printf("\n");

                /* Abort on an empty passphrase. */
                if (i == 0) {
                        printf("aborting...\n");
                        goto done;
                }

#ifdef DEBUG
                printf("Got passphrase: %s with len %d\n",
                    passphrase, strlen(passphrase));
#endif

                switch (kdfhint->generic.type) {
                case SR_CRYPTOKDFT_PKCS5_PBKDF2:
                        if (pkcs5_pbkdf2(passphrase, strlen(passphrase),
                            kdfhint->salt, sizeof(kdfhint->salt),
                            kdfinfo->maskkey, sizeof(kdfinfo->maskkey),
                            kdfhint->rounds) != 0) {
                                printf("pkcs5_pbkdf2 failed\n");
                                goto done;
                        }
                        break;

                case SR_CRYPTOKDFT_BCRYPT_PBKDF:
                        if (bcrypt_pbkdf(passphrase, strlen(passphrase),
                            kdfhint->salt, sizeof(kdfhint->salt),
                            kdfinfo->maskkey, sizeof(kdfinfo->maskkey),
                            kdfhint->rounds) != 0) {
                                printf("bcrypt_pbkdf failed\n");
                                goto done;
                        }
                        break;

                default:
                        printf("unknown KDF type %u\n", kdfhint->generic.type);
                        goto done;
                }

                if (sr_crypto_decrypt_keys(cm, kdfinfo, kp) == 0) {
                        rv = 0;
                        goto done;
                }

                printf("incorrect passphrase\n");
        }

 done:
        explicit_bzero(passphrase, PASSPHRASE_LENGTH);

        return rv;
}

int
sr_crypto_unlock_volume(struct sr_boot_volume *bv)
{
        struct sr_meta_crypto *cm;
        struct sr_boot_keydisk *kd;
        struct sr_meta_opt_item *omi;
        struct sr_crypto_pbkdf *kdfhint;
        struct sr_crypto_kdfinfo kdfinfo;
        u_int8_t *keys = NULL;
        int rv = -1;

        SLIST_FOREACH(omi, &bv->sbv_meta_opt, omi_link)
                if (omi->omi_som->som_type == SR_OPT_CRYPTO)
                        break;

        if (omi == NULL) {
                printf("crypto metadata not found!\n");
                goto done;
        }

        cm = (struct sr_meta_crypto *)omi->omi_som;
        kdfhint = (struct sr_crypto_pbkdf *)&cm->scm_kdfhint;

        switch (cm->scm_mask_alg) {
        case SR_CRYPTOM_AES_ECB_256:
                break;
        default:
                printf("unsupported encryption algorithm %u\n",
                    cm->scm_mask_alg);
                goto done;
        }

        keys = alloc(SR_CRYPTO_KEYBLOCK_BYTES);
        bzero(keys, SR_CRYPTO_KEYBLOCK_BYTES);

        switch (kdfhint->generic.type) {
        case SR_CRYPTOKDFT_KEYDISK:
                SLIST_FOREACH(kd, &sr_keydisks, kd_link) {
                        if (bcmp(&kd->kd_uuid, &bv->sbv_uuid,
                            sizeof(kd->kd_uuid)) == 0)
                                break;
                }
                if (kd == NULL) {
                        printf("keydisk not found\n");
                        goto done;
                }
                bcopy(&kd->kd_key, &kdfinfo.maskkey, sizeof(kdfinfo.maskkey));
                if (sr_crypto_decrypt_keys(cm, &kdfinfo, keys) != 0) {
                        printf("incorrect keydisk\n");
                        goto done;
                }
                break;

        case SR_CRYPTOKDFT_BCRYPT_PBKDF:
        case SR_CRYPTOKDFT_PKCS5_PBKDF2:
                if (sr_crypto_passphrase_decrypt(cm, &kdfinfo, keys) != 0)
                        goto done;
                break;

        default:
                printf("unknown KDF type %u\n", kdfhint->generic.type);
                goto done;
        }

        /* Keys and keydisks will be cleared before boot and from _rtt. */
        bv->sbv_keys = keys;
        bv->sbv_maskkey = alloc(sizeof(kdfinfo.maskkey));
        bcopy(&kdfinfo.maskkey, bv->sbv_maskkey, sizeof(kdfinfo.maskkey));

        rv = 0;

 done:
        explicit_bzero(&kdfinfo, sizeof(kdfinfo));

        if (keys != NULL && rv != 0) {
                explicit_bzero(keys, SR_CRYPTO_KEYBLOCK_BYTES);
                free(keys, SR_CRYPTO_KEYBLOCK_BYTES);
        }

        return (rv);
}