/* Sign a module file using the given key.
 *
 * Copyright © 2014-2016 Red Hat, Inc. All Rights Reserved.
 * Copyright © 2015      Intel Corporation.
 * Copyright © 2016      Hewlett Packard Enterprise Development LP
 *
 * Authors: David Howells <dhowells@redhat.com>
 *          David Woodhouse <dwmw2@infradead.org>
 *          Juerg Haefliger <juerg.haefliger@hpe.com>
 *
 * This program 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 licence, or (at your option) any later version.
 */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <getopt.h>
#include <err.h>
#include <arpa/inet.h>
#include <openssl/opensslv.h>
#include <openssl/bio.h>
#include <openssl/cms.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
# define USE_PKCS11_PROVIDER
# include <openssl/provider.h>
# include <openssl/store.h>
#else
# if !defined(OPENSSL_NO_ENGINE) && !defined(OPENSSL_NO_DEPRECATED_3_0)
#  define USE_PKCS11_ENGINE
#  include <openssl/engine.h>
# endif
#endif
#include "ssl-common.h"

struct module_signature {
        uint8_t         algo;           /* Public-key crypto algorithm [0] */
        uint8_t         hash;           /* Digest algorithm [0] */
        uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
        uint8_t         signer_len;     /* Length of signer's name [0] */
        uint8_t         key_id_len;     /* Length of key identifier [0] */
        uint8_t         __pad[3];
        uint32_t        sig_len;        /* Length of signature data */
};

#define PKEY_ID_PKCS7 2

static char magic_number[] = "~Module signature appended~\n";

static __attribute__((noreturn))
void format(void)
{
        fprintf(stderr,
                "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
        fprintf(stderr,
                "       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
        exit(2);
}

static const char *key_pass;

static int pem_pw_cb(char *buf, int len, int w, void *v)
{
        int pwlen;

        if (!key_pass)
                return -1;

        pwlen = strlen(key_pass);
        if (pwlen >= len)
                return -1;

        strcpy(buf, key_pass);

        /* If it's wrong, don't keep trying it. */
        key_pass = NULL;

        return pwlen;
}

static EVP_PKEY *read_private_key_pkcs11(const char *private_key_name)
{
        EVP_PKEY *private_key = NULL;
#ifdef USE_PKCS11_PROVIDER
        OSSL_STORE_CTX *store;

        if (!OSSL_PROVIDER_try_load(NULL, "pkcs11", true))
                ERR(1, "OSSL_PROVIDER_try_load(pkcs11)");
        if (!OSSL_PROVIDER_try_load(NULL, "default", true))
                ERR(1, "OSSL_PROVIDER_try_load(default)");

        store = OSSL_STORE_open(private_key_name, NULL, NULL, NULL, NULL);
        ERR(!store, "OSSL_STORE_open");

        while (!OSSL_STORE_eof(store)) {
                OSSL_STORE_INFO *info = OSSL_STORE_load(store);

                if (!info) {
                        drain_openssl_errors(__LINE__, 0);
                        continue;
                }
                if (OSSL_STORE_INFO_get_type(info) == OSSL_STORE_INFO_PKEY) {
                        private_key = OSSL_STORE_INFO_get1_PKEY(info);
                        ERR(!private_key, "OSSL_STORE_INFO_get1_PKEY");
                }
                OSSL_STORE_INFO_free(info);
                if (private_key)
                        break;
        }
        OSSL_STORE_close(store);
#elif defined(USE_PKCS11_ENGINE)
        ENGINE *e;

        ENGINE_load_builtin_engines();
        drain_openssl_errors(__LINE__, 1);
        e = ENGINE_by_id("pkcs11");
        ERR(!e, "Load PKCS#11 ENGINE");
        if (ENGINE_init(e))
                drain_openssl_errors(__LINE__, 1);
        else
                ERR(1, "ENGINE_init");
        if (key_pass)
                ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
        private_key = ENGINE_load_private_key(e, private_key_name, NULL, NULL);
        ERR(!private_key, "%s", private_key_name);
#else
        fprintf(stderr, "no pkcs11 engine/provider available\n");
        exit(1);
#endif
        return private_key;
}

static EVP_PKEY *read_private_key(const char *private_key_name)
{
        if (!strncmp(private_key_name, "pkcs11:", 7)) {
                return read_private_key_pkcs11(private_key_name);
        } else {
                EVP_PKEY *private_key;
                BIO *b;

                b = BIO_new_file(private_key_name, "rb");
                ERR(!b, "%s", private_key_name);
                private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
                                                      NULL);
                ERR(!private_key, "%s", private_key_name);
                BIO_free(b);

                return private_key;
        }
}

static X509 *read_x509(const char *x509_name)
{
        unsigned char buf[2];
        X509 *x509;
        BIO *b;
        int n;

        b = BIO_new_file(x509_name, "rb");
        ERR(!b, "%s", x509_name);

        /* Look at the first two bytes of the file to determine the encoding */
        n = BIO_read(b, buf, 2);
        if (n != 2) {
                if (BIO_should_retry(b)) {
                        fprintf(stderr, "%s: Read wanted retry\n", x509_name);
                        exit(1);
                }
                if (n >= 0) {
                        fprintf(stderr, "%s: Short read\n", x509_name);
                        exit(1);
                }
                ERR(1, "%s", x509_name);
        }

        ERR(BIO_reset(b) != 0, "%s", x509_name);

        if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
                /* Assume raw DER encoded X.509 */
                x509 = d2i_X509_bio(b, NULL);
        else
                /* Assume PEM encoded X.509 */
                x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);

        BIO_free(b);
        ERR(!x509, "%s", x509_name);

        return x509;
}

int main(int argc, char **argv)
{
        struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
        char *hash_algo = NULL;
        char *private_key_name = NULL, *raw_sig_name = NULL;
        char *x509_name, *module_name, *dest_name;
        bool save_sig = false, replace_orig;
        bool sign_only = false;
        bool raw_sig = false;
        unsigned char buf[4096];
        unsigned long module_size, sig_size;
        const EVP_MD *digest_algo;
        EVP_PKEY *private_key;
        CMS_ContentInfo *cms = NULL;
        unsigned int use_keyid = 0;
        X509 *x509;
        BIO *bd, *bm;
        int opt, n;
        OpenSSL_add_all_algorithms();
        ERR_load_crypto_strings();
        ERR_clear_error();

        key_pass = getenv("KBUILD_SIGN_PIN");

        do {
                opt = getopt(argc, argv, "sdpk");
                switch (opt) {
                case 's': raw_sig = true; break;
                case 'p': save_sig = true; break;
                case 'd': sign_only = true; save_sig = true; break;
                case 'k': use_keyid = CMS_USE_KEYID; break;
                case -1: break;
                default: format();
                }
        } while (opt != -1);

        argc -= optind;
        argv += optind;
        if (argc < 4 || argc > 5)
                format();

        if (raw_sig) {
                raw_sig_name = argv[0];
                hash_algo = argv[1];
        } else {
                hash_algo = argv[0];
                private_key_name = argv[1];
        }
        x509_name = argv[2];
        module_name = argv[3];
        if (argc == 5 && strcmp(argv[3], argv[4]) != 0) {
                dest_name = argv[4];
                replace_orig = false;
        } else {
                ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
                    "asprintf");
                replace_orig = true;
        }

        /* Open the module file */
        bm = BIO_new_file(module_name, "rb");
        ERR(!bm, "%s", module_name);

        if (!raw_sig) {
                /* Read the private key and the X.509 cert the PKCS#7 message
                 * will point to.
                 */
                private_key = read_private_key(private_key_name);
                x509 = read_x509(x509_name);

                /* Digest the module data. */
                OpenSSL_add_all_digests();
                drain_openssl_errors(__LINE__, 0);
                digest_algo = EVP_get_digestbyname(hash_algo);
                ERR(!digest_algo, "EVP_get_digestbyname");

                unsigned int flags =
                        CMS_NOCERTS |
                        CMS_NOATTR |
                        CMS_PARTIAL |
                        CMS_BINARY |
                        CMS_DETACHED |
                        CMS_STREAM  |
                        CMS_NOSMIMECAP |
#ifdef CMS_NO_SIGNING_TIME
                        CMS_NO_SIGNING_TIME |
#endif
                        use_keyid;

#if OPENSSL_VERSION_NUMBER >= 0x30000000L && OPENSSL_VERSION_NUMBER < 0x40000000L
                if (EVP_PKEY_is_a(private_key, "ML-DSA-44") ||
                    EVP_PKEY_is_a(private_key, "ML-DSA-65") ||
                    EVP_PKEY_is_a(private_key, "ML-DSA-87")) {
                         /* ML-DSA + CMS_NOATTR is not supported in openssl-3.5
                          * and before.
                          */
                        flags &= ~CMS_NOATTR;
                }
#endif

                /* Load the signature message from the digest buffer. */
                cms = CMS_sign(NULL, NULL, NULL, NULL, flags);
                ERR(!cms, "CMS_sign");

                ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo, flags),
                    "CMS_add1_signer");
                ERR(CMS_final(cms, bm, NULL, flags) != 1,
                    "CMS_final");

                if (save_sig) {
                        char *sig_file_name;
                        BIO *b;

                        ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
                            "asprintf");
                        b = BIO_new_file(sig_file_name, "wb");
                        ERR(!b, "%s", sig_file_name);
                        ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) != 1,
                            "%s", sig_file_name);
                        BIO_free(b);
                }

                if (sign_only) {
                        BIO_free(bm);
                        return 0;
                }
        }

        /* Open the destination file now so that we can shovel the module data
         * across as we read it.
         */
        bd = BIO_new_file(dest_name, "wb");
        ERR(!bd, "%s", dest_name);

        /* Append the marker and the PKCS#7 message to the destination file */
        ERR(BIO_reset(bm) < 0, "%s", module_name);
        while ((n = BIO_read(bm, buf, sizeof(buf))),
               n > 0) {
                ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
        }
        BIO_free(bm);
        ERR(n < 0, "%s", module_name);
        module_size = BIO_number_written(bd);

        if (!raw_sig) {
                ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) != 1, "%s", dest_name);
        } else {
                BIO *b;

                /* Read the raw signature file and write the data to the
                 * destination file
                 */
                b = BIO_new_file(raw_sig_name, "rb");
                ERR(!b, "%s", raw_sig_name);
                while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
                        ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
                BIO_free(b);
        }

        sig_size = BIO_number_written(bd) - module_size;
        sig_info.sig_len = htonl(sig_size);
        ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
        ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);

        ERR(BIO_free(bd) != 1, "%s", dest_name);

        /* Finally, if we're signing in place, replace the original. */
        if (replace_orig)
                ERR(rename(dest_name, module_name) < 0, "%s", dest_name);

        return 0;
}