// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2013, Google Inc.
 */

#include "mkimage.h"
#include <stdio.h>
#include <string.h>
#include <image.h>
#include <time.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/evp.h>
#include <openssl/engine.h>

#if OPENSSL_VERSION_NUMBER >= 0x10000000L
#define HAVE_ERR_REMOVE_THREAD_STATE
#endif

#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
        (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
static void RSA_get0_key(const RSA *r,
                 const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
{
   if (n != NULL)
       *n = r->n;
   if (e != NULL)
       *e = r->e;
   if (d != NULL)
       *d = r->d;
}
#endif

static int rsa_err(const char *msg)
{
        unsigned long sslErr = ERR_get_error();

        fprintf(stderr, "%s", msg);
        fprintf(stderr, ": %s\n",
                ERR_error_string(sslErr, 0));

        return -1;
}

/**
 * rsa_pem_get_pub_key() - read a public key from a .crt file
 *
 * @keydir:     Directory containins the key
 * @name        Name of key file (will have a .crt extension)
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_pem_get_pub_key(const char *keydir, const char *name, RSA **rsap)
{
        char path[1024];
        EVP_PKEY *key;
        X509 *cert;
        RSA *rsa;
        FILE *f;
        int ret;

        *rsap = NULL;
        snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
        f = fopen(path, "r");
        if (!f) {
                fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
                        path, strerror(errno));
                return -EACCES;
        }

        /* Read the certificate */
        cert = NULL;
        if (!PEM_read_X509(f, &cert, NULL, NULL)) {
                rsa_err("Couldn't read certificate");
                ret = -EINVAL;
                goto err_cert;
        }

        /* Get the public key from the certificate. */
        key = X509_get_pubkey(cert);
        if (!key) {
                rsa_err("Couldn't read public key\n");
                ret = -EINVAL;
                goto err_pubkey;
        }

        /* Convert to a RSA_style key. */
        rsa = EVP_PKEY_get1_RSA(key);
        if (!rsa) {
                rsa_err("Couldn't convert to a RSA style key");
                ret = -EINVAL;
                goto err_rsa;
        }
        fclose(f);
        EVP_PKEY_free(key);
        X509_free(cert);
        *rsap = rsa;

        return 0;

err_rsa:
        EVP_PKEY_free(key);
err_pubkey:
        X509_free(cert);
err_cert:
        fclose(f);
        return ret;
}

/**
 * rsa_engine_get_pub_key() - read a public key from given engine
 *
 * @keydir:     Key prefix
 * @name        Name of key
 * @engine      Engine to use
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_engine_get_pub_key(const char *keydir, const char *name,
                                  ENGINE *engine, RSA **rsap)
{
        const char *engine_id;
        char key_id[1024];
        EVP_PKEY *key;
        RSA *rsa;
        int ret;

        *rsap = NULL;

        engine_id = ENGINE_get_id(engine);

        if (engine_id && !strcmp(engine_id, "pkcs11")) {
                if (keydir)
                        snprintf(key_id, sizeof(key_id),
                                 "pkcs11:%s;object=%s;type=public",
                                 keydir, name);
                else
                        snprintf(key_id, sizeof(key_id),
                                 "pkcs11:object=%s;type=public",
                                 name);
        } else if (engine_id) {
                if (keydir)
                        snprintf(key_id, sizeof(key_id),
                                 "%s%s",
                                 keydir, name);
                else
                        snprintf(key_id, sizeof(key_id),
                                 "%s",
                                 name);
        } else {
                fprintf(stderr, "Engine not supported\n");
                return -ENOTSUP;
        }

        key = ENGINE_load_public_key(engine, key_id, NULL, NULL);
        if (!key)
                return rsa_err("Failure loading public key from engine");

        /* Convert to a RSA_style key. */
        rsa = EVP_PKEY_get1_RSA(key);
        if (!rsa) {
                rsa_err("Couldn't convert to a RSA style key");
                ret = -EINVAL;
                goto err_rsa;
        }

        EVP_PKEY_free(key);
        *rsap = rsa;

        return 0;

err_rsa:
        EVP_PKEY_free(key);
        return ret;
}

/**
 * rsa_get_pub_key() - read a public key
 *
 * @keydir:     Directory containing the key (PEM file) or key prefix (engine)
 * @name        Name of key file (will have a .crt extension)
 * @engine      Engine to use
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_get_pub_key(const char *keydir, const char *name,
                           ENGINE *engine, RSA **rsap)
{
        if (engine)
                return rsa_engine_get_pub_key(keydir, name, engine, rsap);
        return rsa_pem_get_pub_key(keydir, name, rsap);
}

/**
 * rsa_pem_get_priv_key() - read a private key from a .key file
 *
 * @keydir:     Directory containing the key
 * @name        Name of key file (will have a .key extension)
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_pem_get_priv_key(const char *keydir, const char *name,
                                RSA **rsap)
{
        char path[1024];
        RSA *rsa;
        FILE *f;

        *rsap = NULL;
        snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
        f = fopen(path, "r");
        if (!f) {
                fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
                        path, strerror(errno));
                return -ENOENT;
        }

        rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
        if (!rsa) {
                rsa_err("Failure reading private key");
                fclose(f);
                return -EPROTO;
        }
        fclose(f);
        *rsap = rsa;

        return 0;
}

/**
 * rsa_engine_get_priv_key() - read a private key from given engine
 *
 * @keydir:     Key prefix
 * @name        Name of key
 * @engine      Engine to use
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_engine_get_priv_key(const char *keydir, const char *name,
                                   ENGINE *engine, RSA **rsap)
{
        const char *engine_id;
        char key_id[1024];
        EVP_PKEY *key;
        RSA *rsa;
        int ret;

        *rsap = NULL;

        engine_id = ENGINE_get_id(engine);

        if (engine_id && !strcmp(engine_id, "pkcs11")) {
                if (keydir)
                        snprintf(key_id, sizeof(key_id),
                                 "pkcs11:%s;object=%s;type=private",
                                 keydir, name);
                else
                        snprintf(key_id, sizeof(key_id),
                                 "pkcs11:object=%s;type=private",
                                 name);
        } else if (engine_id) {
                if (keydir)
                        snprintf(key_id, sizeof(key_id),
                                 "%s%s",
                                 keydir, name);
                else
                        snprintf(key_id, sizeof(key_id),
                                 "%s",
                                 name);
        } else {
                fprintf(stderr, "Engine not supported\n");
                return -ENOTSUP;
        }

        key = ENGINE_load_private_key(engine, key_id, NULL, NULL);
        if (!key)
                return rsa_err("Failure loading private key from engine");

        /* Convert to a RSA_style key. */
        rsa = EVP_PKEY_get1_RSA(key);
        if (!rsa) {
                rsa_err("Couldn't convert to a RSA style key");
                ret = -EINVAL;
                goto err_rsa;
        }

        EVP_PKEY_free(key);
        *rsap = rsa;

        return 0;

err_rsa:
        EVP_PKEY_free(key);
        return ret;
}

/**
 * rsa_get_priv_key() - read a private key
 *
 * @keydir:     Directory containing the key (PEM file) or key prefix (engine)
 * @name        Name of key
 * @engine      Engine to use for signing
 * @rsap        Returns RSA object, or NULL on failure
 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
 */
static int rsa_get_priv_key(const char *keydir, const char *name,
                            ENGINE *engine, RSA **rsap)
{
        if (engine)
                return rsa_engine_get_priv_key(keydir, name, engine, rsap);
        return rsa_pem_get_priv_key(keydir, name, rsap);
}

static int rsa_init(void)
{
        int ret;

#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
        (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
        ret = SSL_library_init();
#else
        ret = OPENSSL_init_ssl(0, NULL);
#endif
        if (!ret) {
                fprintf(stderr, "Failure to init SSL library\n");
                return -1;
        }
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
        (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
        SSL_load_error_strings();

        OpenSSL_add_all_algorithms();
        OpenSSL_add_all_digests();
        OpenSSL_add_all_ciphers();
#endif

        return 0;
}

static int rsa_engine_init(const char *engine_id, ENGINE **pe)
{
        ENGINE *e;
        int ret;

        ENGINE_load_builtin_engines();

        e = ENGINE_by_id(engine_id);
        if (!e) {
                fprintf(stderr, "Engine isn't available\n");
                ret = -1;
                goto err_engine_by_id;
        }

        if (!ENGINE_init(e)) {
                fprintf(stderr, "Couldn't initialize engine\n");
                ret = -1;
                goto err_engine_init;
        }

        if (!ENGINE_set_default_RSA(e)) {
                fprintf(stderr, "Couldn't set engine as default for RSA\n");
                ret = -1;
                goto err_set_rsa;
        }

        *pe = e;

        return 0;

err_set_rsa:
        ENGINE_finish(e);
err_engine_init:
        ENGINE_free(e);
err_engine_by_id:
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
        (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
        ENGINE_cleanup();
#endif
        return ret;
}

static void rsa_remove(void)
{
#if OPENSSL_VERSION_NUMBER < 0x10100000L || \
        (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
        CRYPTO_cleanup_all_ex_data();
        ERR_free_strings();
#ifdef HAVE_ERR_REMOVE_THREAD_STATE
        ERR_remove_thread_state(NULL);
#else
        ERR_remove_state(0);
#endif
        EVP_cleanup();
#endif
}

static void rsa_engine_remove(ENGINE *e)
{
        if (e) {
                ENGINE_finish(e);
                ENGINE_free(e);
        }
}

static int rsa_sign_with_key(RSA *rsa, struct padding_algo *padding_algo,
                             struct checksum_algo *checksum_algo,
                const struct image_region region[], int region_count,
                uint8_t **sigp, uint *sig_size)
{
        EVP_PKEY *key;
        EVP_PKEY_CTX *ckey;
        EVP_MD_CTX *context;
        int ret = 0;
        size_t size;
        uint8_t *sig;
        int i;

        key = EVP_PKEY_new();
        if (!key)
                return rsa_err("EVP_PKEY object creation failed");

        if (!EVP_PKEY_set1_RSA(key, rsa)) {
                ret = rsa_err("EVP key setup failed");
                goto err_set;
        }

        size = EVP_PKEY_size(key);
        sig = malloc(size);
        if (!sig) {
                fprintf(stderr, "Out of memory for signature (%zu bytes)\n",
                        size);
                ret = -ENOMEM;
                goto err_alloc;
        }

        context = EVP_MD_CTX_create();
        if (!context) {
                ret = rsa_err("EVP context creation failed");
                goto err_create;
        }
        EVP_MD_CTX_init(context);

        ckey = EVP_PKEY_CTX_new(key, NULL);
        if (!ckey) {
                ret = rsa_err("EVP key context creation failed");
                goto err_create;
        }

        if (EVP_DigestSignInit(context, &ckey,
                               checksum_algo->calculate_sign(),
                               NULL, key) <= 0) {
                ret = rsa_err("Signer setup failed");
                goto err_sign;
        }

#ifdef CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT
        if (padding_algo && !strcmp(padding_algo->name, "pss")) {
                if (EVP_PKEY_CTX_set_rsa_padding(ckey,
                                                 RSA_PKCS1_PSS_PADDING) <= 0) {
                        ret = rsa_err("Signer padding setup failed");
                        goto err_sign;
                }
        }
#endif /* CONFIG_FIT_ENABLE_RSASSA_PSS_SUPPORT */

        for (i = 0; i < region_count; i++) {
                if (!EVP_DigestSignUpdate(context, region[i].data,
                                          region[i].size)) {
                        ret = rsa_err("Signing data failed");
                        goto err_sign;
                }
        }

        if (!EVP_DigestSignFinal(context, sig, &size)) {
                ret = rsa_err("Could not obtain signature");
                goto err_sign;
        }

        #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
                (defined(LIBRESSL_VERSION_NUMBER) && LIBRESSL_VERSION_NUMBER < 0x02070000fL)
                EVP_MD_CTX_cleanup(context);
        #else
                EVP_MD_CTX_reset(context);
        #endif
        EVP_MD_CTX_destroy(context);
        EVP_PKEY_free(key);

        debug("Got signature: %d bytes, expected %zu\n", *sig_size, size);
        *sigp = sig;
        *sig_size = size;

        return 0;

err_sign:
        EVP_MD_CTX_destroy(context);
err_create:
        free(sig);
err_alloc:
err_set:
        EVP_PKEY_free(key);
        return ret;
}

int rsa_sign(struct image_sign_info *info,
             const struct image_region region[], int region_count,
             uint8_t **sigp, uint *sig_len)
{
        RSA *rsa;
        ENGINE *e = NULL;
        int ret;

        ret = rsa_init();
        if (ret)
                return ret;

        if (info->engine_id) {
                ret = rsa_engine_init(info->engine_id, &e);
                if (ret)
                        goto err_engine;
        }

        ret = rsa_get_priv_key(info->keydir, info->keyname, e, &rsa);
        if (ret)
                goto err_priv;
        ret = rsa_sign_with_key(rsa, info->padding, info->checksum, region,
                                region_count, sigp, sig_len);
        if (ret)
                goto err_sign;

        RSA_free(rsa);
        if (info->engine_id)
                rsa_engine_remove(e);
        rsa_remove();

        return ret;

err_sign:
        RSA_free(rsa);
err_priv:
        if (info->engine_id)
                rsa_engine_remove(e);
err_engine:
        rsa_remove();
        return ret;
}

/*
 * rsa_get_exponent(): - Get the public exponent from an RSA key
 */
static int rsa_get_exponent(RSA *key, uint64_t *e)
{
        int ret;
        BIGNUM *bn_te;
        const BIGNUM *key_e;
        uint64_t te;

        ret = -EINVAL;
        bn_te = NULL;

        if (!e)
                goto cleanup;

        RSA_get0_key(key, NULL, &key_e, NULL);
        if (BN_num_bits(key_e) > 64)
                goto cleanup;

        *e = BN_get_word(key_e);

        if (BN_num_bits(key_e) < 33) {
                ret = 0;
                goto cleanup;
        }

        bn_te = BN_dup(key_e);
        if (!bn_te)
                goto cleanup;

        if (!BN_rshift(bn_te, bn_te, 32))
                goto cleanup;

        if (!BN_mask_bits(bn_te, 32))
                goto cleanup;

        te = BN_get_word(bn_te);
        te <<= 32;
        *e |= te;
        ret = 0;

cleanup:
        if (bn_te)
                BN_free(bn_te);

        return ret;
}

/*
 * rsa_get_params(): - Get the important parameters of an RSA public key
 */
int rsa_get_params(RSA *key, uint64_t *exponent, uint32_t *n0_invp,
                   BIGNUM **modulusp, BIGNUM **r_squaredp)
{
        BIGNUM *big1, *big2, *big32, *big2_32;
        BIGNUM *n, *r, *r_squared, *tmp;
        const BIGNUM *key_n;
        BN_CTX *bn_ctx = BN_CTX_new();
        int ret = 0;

        /* Initialize BIGNUMs */
        big1 = BN_new();
        big2 = BN_new();
        big32 = BN_new();
        r = BN_new();
        r_squared = BN_new();
        tmp = BN_new();
        big2_32 = BN_new();
        n = BN_new();
        if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
            !n) {
                fprintf(stderr, "Out of memory (bignum)\n");
                return -ENOMEM;
        }

        if (0 != rsa_get_exponent(key, exponent))
                ret = -1;

        RSA_get0_key(key, &key_n, NULL, NULL);
        if (!BN_copy(n, key_n) || !BN_set_word(big1, 1L) ||
            !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
                ret = -1;

        /* big2_32 = 2^32 */
        if (!BN_exp(big2_32, big2, big32, bn_ctx))
                ret = -1;

        /* Calculate n0_inv = -1 / n[0] mod 2^32 */
        if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
            !BN_sub(tmp, big2_32, tmp))
                ret = -1;
        *n0_invp = BN_get_word(tmp);

        /* Calculate R = 2^(# of key bits) */
        if (!BN_set_word(tmp, BN_num_bits(n)) ||
            !BN_exp(r, big2, tmp, bn_ctx))
                ret = -1;

        /* Calculate r_squared = R^2 mod n */
        if (!BN_copy(r_squared, r) ||
            !BN_mul(tmp, r_squared, r, bn_ctx) ||
            !BN_mod(r_squared, tmp, n, bn_ctx))
                ret = -1;

        *modulusp = n;
        *r_squaredp = r_squared;

        BN_free(big1);
        BN_free(big2);
        BN_free(big32);
        BN_free(r);
        BN_free(tmp);
        BN_free(big2_32);
        if (ret) {
                fprintf(stderr, "Bignum operations failed\n");
                return -ENOMEM;
        }

        return ret;
}

static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
                          BIGNUM *num, int num_bits)
{
        int nwords = num_bits / 32;
        int size;
        uint32_t *buf, *ptr;
        BIGNUM *tmp, *big2, *big32, *big2_32;
        BN_CTX *ctx;
        int ret;

        tmp = BN_new();
        big2 = BN_new();
        big32 = BN_new();
        big2_32 = BN_new();

        /*
         * Note: This code assumes that all of the above succeed, or all fail.
         * In practice memory allocations generally do not fail (unless the
         * process is killed), so it does not seem worth handling each of these
         * as a separate case. Technicaly this could leak memory on failure,
         * but a) it won't happen in practice, and b) it doesn't matter as we
         * will immediately exit with a failure code.
         */
        if (!tmp || !big2 || !big32 || !big2_32) {
                fprintf(stderr, "Out of memory (bignum)\n");
                return -ENOMEM;
        }
        ctx = BN_CTX_new();
        if (!tmp) {
                fprintf(stderr, "Out of memory (bignum context)\n");
                return -ENOMEM;
        }
        BN_set_word(big2, 2L);
        BN_set_word(big32, 32L);
        BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */

        size = nwords * sizeof(uint32_t);
        buf = malloc(size);
        if (!buf) {
                fprintf(stderr, "Out of memory (%d bytes)\n", size);
                return -ENOMEM;
        }

        /* Write out modulus as big endian array of integers */
        for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
                BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
                *ptr = cpu_to_fdt32(BN_get_word(tmp));
                BN_rshift(num, num, 32); /*  N = N/B */
        }

        /*
         * We try signing with successively increasing size values, so this
         * might fail several times
         */
        ret = fdt_setprop(blob, noffset, prop_name, buf, size);
        free(buf);
        BN_free(tmp);
        BN_free(big2);
        BN_free(big32);
        BN_free(big2_32);

        return ret ? -FDT_ERR_NOSPACE : 0;
}

int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
{
        BIGNUM *modulus, *r_squared;
        uint64_t exponent;
        uint32_t n0_inv;
        int parent, node;
        char name[100];
        int ret;
        int bits;
        RSA *rsa;
        ENGINE *e = NULL;

        debug("%s: Getting verification data\n", __func__);
        if (info->engine_id) {
                ret = rsa_engine_init(info->engine_id, &e);
                if (ret)
                        return ret;
        }
        ret = rsa_get_pub_key(info->keydir, info->keyname, e, &rsa);
        if (ret)
                goto err_get_pub_key;
        ret = rsa_get_params(rsa, &exponent, &n0_inv, &modulus, &r_squared);
        if (ret)
                goto err_get_params;
        bits = BN_num_bits(modulus);
        parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
        if (parent == -FDT_ERR_NOTFOUND) {
                parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
                if (parent < 0) {
                        ret = parent;
                        if (ret != -FDT_ERR_NOSPACE) {
                                fprintf(stderr, "Couldn't create signature node: %s\n",
                                        fdt_strerror(parent));
                        }
                }
        }
        if (ret)
                goto done;

        /* Either create or overwrite the named key node */
        snprintf(name, sizeof(name), "key-%s", info->keyname);
        node = fdt_subnode_offset(keydest, parent, name);
        if (node == -FDT_ERR_NOTFOUND) {
                node = fdt_add_subnode(keydest, parent, name);
                if (node < 0) {
                        ret = node;
                        if (ret != -FDT_ERR_NOSPACE) {
                                fprintf(stderr, "Could not create key subnode: %s\n",
                                        fdt_strerror(node));
                        }
                }
        } else if (node < 0) {
                fprintf(stderr, "Cannot select keys parent: %s\n",
                        fdt_strerror(node));
                ret = node;
        }

        if (!ret) {
                ret = fdt_setprop_string(keydest, node, "key-name-hint",
                                 info->keyname);
        }
        if (!ret)
                ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
        if (!ret)
                ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
        if (!ret) {
                ret = fdt_setprop_u64(keydest, node, "rsa,exponent", exponent);
        }
        if (!ret) {
                ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus,
                                     bits);
        }
        if (!ret) {
                ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared,
                                     bits);
        }
        if (!ret) {
                ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
                                         info->name);
        }
        if (!ret && info->require_keys) {
                ret = fdt_setprop_string(keydest, node, "required",
                                         info->require_keys);
        }
done:
        BN_free(modulus);
        BN_free(r_squared);
        if (ret)
                ret = ret == -FDT_ERR_NOSPACE ? -ENOSPC : -EIO;
err_get_params:
        RSA_free(rsa);
err_get_pub_key:
        if (info->engine_id)
                rsa_engine_remove(e);

        return ret;
}