/*

 * Copyright 1999-2018 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/* S/MIME utility function */

#include <stdio.h>

#include <string.h>

#include "apps.h"

#include "progs.h"

#include <openssl/crypto.h>

#include <openssl/pem.h>

#include <openssl/err.h>

#include <openssl/x509_vfy.h>

#include <openssl/x509v3.h>

static int save_certs(char *signerfile, STACK_OF(X509) *signers);

static int smime_cb(int ok, X509_STORE_CTX *ctx);

#define SMIME_OP        0x10

#define SMIME_IP        0x20

#define SMIME_SIGNERS   0x40

#define SMIME_ENCRYPT   (1 | SMIME_OP)

#define SMIME_DECRYPT   (2 | SMIME_IP)

#define SMIME_SIGN      (3 | SMIME_OP | SMIME_SIGNERS)

#define SMIME_VERIFY    (4 | SMIME_IP)

#define SMIME_PK7OUT    (5 | SMIME_IP | SMIME_OP)

#define SMIME_RESIGN    (6 | SMIME_IP | SMIME_OP | SMIME_SIGNERS)

typedef enum OPTION_choice {

    OPT_ERR = -1, OPT_EOF = 0, OPT_HELP,

    OPT_ENCRYPT, OPT_DECRYPT, OPT_SIGN, OPT_RESIGN, OPT_VERIFY,

    OPT_PK7OUT, OPT_TEXT, OPT_NOINTERN, OPT_NOVERIFY, OPT_NOCHAIN,

    OPT_NOCERTS, OPT_NOATTR, OPT_NODETACH, OPT_NOSMIMECAP,

    OPT_BINARY, OPT_NOSIGS, OPT_STREAM, OPT_INDEF, OPT_NOINDEF,

    OPT_CRLFEOL, OPT_ENGINE, OPT_PASSIN,

    OPT_TO, OPT_FROM, OPT_SUBJECT, OPT_SIGNER, OPT_RECIP, OPT_MD,

    OPT_CIPHER, OPT_INKEY, OPT_KEYFORM, OPT_CERTFILE, OPT_CAFILE,

    OPT_R_ENUM,

    OPT_V_ENUM,

    OPT_CAPATH, OPT_NOCAFILE, OPT_NOCAPATH, OPT_IN, OPT_INFORM, OPT_OUT,

    OPT_OUTFORM, OPT_CONTENT

} OPTION_CHOICE;

const OPTIONS smime_options[] = {

    {OPT_HELP_STR, 1, '-', "Usage: %s [options] cert.pem...\n"},

    {OPT_HELP_STR, 1, '-',

        "  cert.pem... recipient certs for encryption\n"},

    {OPT_HELP_STR, 1, '-', "Valid options are:\n"},

    {"help", OPT_HELP, '-', "Display this summary"},

    {"encrypt", OPT_ENCRYPT, '-', "Encrypt message"},

    {"decrypt", OPT_DECRYPT, '-', "Decrypt encrypted message"},

    {"sign", OPT_SIGN, '-', "Sign message"},

    {"verify", OPT_VERIFY, '-', "Verify signed message"},

    {"pk7out", OPT_PK7OUT, '-', "Output PKCS#7 structure"},

    {"nointern", OPT_NOINTERN, '-',

     "Don't search certificates in message for signer"},

    {"nosigs", OPT_NOSIGS, '-', "Don't verify message signature"},

    {"noverify", OPT_NOVERIFY, '-', "Don't verify signers certificate"},

    {"nocerts", OPT_NOCERTS, '-',

     "Don't include signers certificate when signing"},

    {"nodetach", OPT_NODETACH, '-', "Use opaque signing"},

    {"noattr", OPT_NOATTR, '-', "Don't include any signed attributes"},

    {"binary", OPT_BINARY, '-', "Don't translate message to text"},

    {"certfile", OPT_CERTFILE, '<', "Other certificates file"},

    {"signer", OPT_SIGNER, 's', "Signer certificate file"},

    {"recip", OPT_RECIP, '<', "Recipient certificate file for decryption"},

    {"in", OPT_IN, '<', "Input file"},

    {"inform", OPT_INFORM, 'c', "Input format SMIME (default), PEM or DER"},

    {"inkey", OPT_INKEY, 's',

     "Input private key (if not signer or recipient)"},

    {"keyform", OPT_KEYFORM, 'f', "Input private key format (PEM or ENGINE)"},

    {"out", OPT_OUT, '>', "Output file"},

    {"outform", OPT_OUTFORM, 'c',

     "Output format SMIME (default), PEM or DER"},

    {"content", OPT_CONTENT, '<',

     "Supply or override content for detached signature"},

    {"to", OPT_TO, 's', "To address"},

    {"from", OPT_FROM, 's', "From address"},

    {"subject", OPT_SUBJECT, 's', "Subject"},

    {"text", OPT_TEXT, '-', "Include or delete text MIME headers"},

    {"CApath", OPT_CAPATH, '/', "Trusted certificates directory"},

    {"CAfile", OPT_CAFILE, '<', "Trusted certificates file"},

    {"no-CAfile", OPT_NOCAFILE, '-',

     "Do not load the default certificates file"},

    {"no-CApath", OPT_NOCAPATH, '-',

     "Do not load certificates from the default certificates directory"},

    {"resign", OPT_RESIGN, '-', "Resign a signed message"},

    {"nochain", OPT_NOCHAIN, '-',

     "set PKCS7_NOCHAIN so certificates contained in the message are not used as untrusted CAs" },

    {"nosmimecap", OPT_NOSMIMECAP, '-', "Omit the SMIMECapabilities attribute"},

    {"stream", OPT_STREAM, '-', "Enable CMS streaming" },

    {"indef", OPT_INDEF, '-', "Same as -stream" },

    {"noindef", OPT_NOINDEF, '-', "Disable CMS streaming"},

    {"crlfeol", OPT_CRLFEOL, '-', "Use CRLF as EOL termination instead of CR only"},

    OPT_R_OPTIONS,

    {"passin", OPT_PASSIN, 's', "Input file pass phrase source"},

    {"md", OPT_MD, 's', "Digest algorithm to use when signing or resigning"},

    {"", OPT_CIPHER, '-', "Any supported cipher"},

    OPT_V_OPTIONS,

#ifndef OPENSSL_NO_ENGINE

    {"engine", OPT_ENGINE, 's', "Use engine, possibly a hardware device"},

#endif

    {NULL}

};

int smime_main(int argc, char **argv)

{

    BIO *in = NULL, *out = NULL, *indata = NULL;

    EVP_PKEY *key = NULL;

    PKCS7 *p7 = NULL;

    STACK_OF(OPENSSL_STRING) *sksigners = NULL, *skkeys = NULL;

    STACK_OF(X509) *encerts = NULL, *other = NULL;

    X509 *cert = NULL, *recip = NULL, *signer = NULL;

    X509_STORE *store = NULL;

    X509_VERIFY_PARAM *vpm = NULL;

    const EVP_CIPHER *cipher = NULL;

    const EVP_MD *sign_md = NULL;

    const char *CAfile = NULL, *CApath = NULL, *prog = NULL;

    char *certfile = NULL, *keyfile = NULL, *contfile = NULL;

    char *infile = NULL, *outfile = NULL, *signerfile = NULL, *recipfile = NULL;

    char *passinarg = NULL, *passin = NULL, *to = NULL, *from = NULL, *subject = NULL;

    OPTION_CHOICE o;

    int noCApath = 0, noCAfile = 0;

    int flags = PKCS7_DETACHED, operation = 0, ret = 0, indef = 0;

    int informat = FORMAT_SMIME, outformat = FORMAT_SMIME, keyform =

        FORMAT_PEM;

    int vpmtouched = 0, rv = 0;

    ENGINE *e = NULL;

    const char *mime_eol = "\n";

    if ((vpm = X509_VERIFY_PARAM_new()) == NULL)

        return 1;

    prog = opt_init(argc, argv, smime_options);

    while ((o = opt_next()) != OPT_EOF) {

        switch (o) {

        case OPT_EOF:

        case OPT_ERR:

 opthelp:

            BIO_printf(bio_err, "%s: Use -help for summary.\n", prog);

            goto end;

        case OPT_HELP:

            opt_help(smime_options);

            ret = 0;

            goto end;

        case OPT_INFORM:

            if (!opt_format(opt_arg(), OPT_FMT_PDS, &informat))

                goto opthelp;

            break;

        case OPT_IN:

            infile = opt_arg();

            break;

        case OPT_OUTFORM:

            if (!opt_format(opt_arg(), OPT_FMT_PDS, &outformat))

                goto opthelp;

            break;

        case OPT_OUT:

            outfile = opt_arg();

            break;

        case OPT_ENCRYPT:

            operation = SMIME_ENCRYPT;

            break;

        case OPT_DECRYPT:

            operation = SMIME_DECRYPT;

            break;

        case OPT_SIGN:

            operation = SMIME_SIGN;

            break;

        case OPT_RESIGN:

            operation = SMIME_RESIGN;

            break;

        case OPT_VERIFY:

            operation = SMIME_VERIFY;

            break;

        case OPT_PK7OUT:

            operation = SMIME_PK7OUT;

            break;

        case OPT_TEXT:

            flags |= PKCS7_TEXT;

            break;

        case OPT_NOINTERN:

            flags |= PKCS7_NOINTERN;

            break;

        case OPT_NOVERIFY:

            flags |= PKCS7_NOVERIFY;

            break;

        case OPT_NOCHAIN:

            flags |= PKCS7_NOCHAIN;

            break;

        case OPT_NOCERTS:

            flags |= PKCS7_NOCERTS;

            break;

        case OPT_NOATTR:

            flags |= PKCS7_NOATTR;

            break;

        case OPT_NODETACH:

            flags &= ~PKCS7_DETACHED;

            break;

        case OPT_NOSMIMECAP:

            flags |= PKCS7_NOSMIMECAP;

            break;

        case OPT_BINARY:

            flags |= PKCS7_BINARY;

            break;

        case OPT_NOSIGS:

            flags |= PKCS7_NOSIGS;

            break;

        case OPT_STREAM:

        case OPT_INDEF:

            indef = 1;

            break;

        case OPT_NOINDEF:

            indef = 0;

            break;

        case OPT_CRLFEOL:

            flags |= PKCS7_CRLFEOL;

            mime_eol = "\r\n";

            break;

        case OPT_R_CASES:

            if (!opt_rand(o))

                goto end;

            break;

        case OPT_ENGINE:

            e = setup_engine(opt_arg(), 0);

            break;

        case OPT_PASSIN:

            passinarg = opt_arg();

            break;

        case OPT_TO:

            to = opt_arg();

            break;

        case OPT_FROM:

            from = opt_arg();

            break;

        case OPT_SUBJECT:

            subject = opt_arg();

            break;

        case OPT_SIGNER:

            /* If previous -signer argument add signer to list */

            if (signerfile != NULL) {

                if (sksigners == NULL

                    && (sksigners = sk_OPENSSL_STRING_new_null()) == NULL)

                    goto end;

                sk_OPENSSL_STRING_push(sksigners, signerfile);

                if (keyfile == NULL)

                    keyfile = signerfile;

                if (skkeys == NULL

                    && (skkeys = sk_OPENSSL_STRING_new_null()) == NULL)

                    goto end;

                sk_OPENSSL_STRING_push(skkeys, keyfile);

                keyfile = NULL;

            }

            signerfile = opt_arg();

            break;

        case OPT_RECIP:

            recipfile = opt_arg();

            break;

        case OPT_MD:

            if (!opt_md(opt_arg(), &sign_md))

                goto opthelp;

            break;

        case OPT_CIPHER:

            if (!opt_cipher(opt_unknown(), &cipher))

                goto opthelp;

            break;

        case OPT_INKEY:

            /* If previous -inkey argument add signer to list */

            if (keyfile != NULL) {

                if (signerfile == NULL) {

                    BIO_printf(bio_err,

                               "%s: Must have -signer before -inkey\n", prog);

                    goto opthelp;

                }

                if (sksigners == NULL

                    && (sksigners = sk_OPENSSL_STRING_new_null()) == NULL)

                    goto end;

                sk_OPENSSL_STRING_push(sksigners, signerfile);

                signerfile = NULL;

                if (skkeys == NULL

                    && (skkeys = sk_OPENSSL_STRING_new_null()) == NULL)

                    goto end;

                sk_OPENSSL_STRING_push(skkeys, keyfile);

            }

            keyfile = opt_arg();

            break;

        case OPT_KEYFORM:

            if (!opt_format(opt_arg(), OPT_FMT_ANY, &keyform))

                goto opthelp;

            break;

        case OPT_CERTFILE:

            certfile = opt_arg();

            break;

        case OPT_CAFILE:

            CAfile = opt_arg();

            break;

        case OPT_CAPATH:

            CApath = opt_arg();

            break;

        case OPT_NOCAFILE:

            noCAfile = 1;

            break;

        case OPT_NOCAPATH:

            noCApath = 1;

            break;

        case OPT_CONTENT:

            contfile = opt_arg();

            break;

        case OPT_V_CASES:

            if (!opt_verify(o, vpm))

                goto opthelp;

            vpmtouched++;

            break;

        }

    }

    argc = opt_num_rest();

    argv = opt_rest();

    if (!(operation & SMIME_SIGNERS) && (skkeys != NULL || sksigners != NULL)) {

        BIO_puts(bio_err, "Multiple signers or keys not allowed\n");

        goto opthelp;

    }

    if (operation & SMIME_SIGNERS) {

        /* Check to see if any final signer needs to be appended */

        if (keyfile && !signerfile) {

            BIO_puts(bio_err, "Illegal -inkey without -signer\n");

            goto opthelp;

        }

        if (signerfile != NULL) {

            if (sksigners == NULL

                && (sksigners = sk_OPENSSL_STRING_new_null()) == NULL)

                goto end;

            sk_OPENSSL_STRING_push(sksigners, signerfile);

            if (!skkeys && (skkeys = sk_OPENSSL_STRING_new_null()) == NULL)

                goto end;

            if (!keyfile)

                keyfile = signerfile;

            sk_OPENSSL_STRING_push(skkeys, keyfile);

        }

        if (sksigners == NULL) {

            BIO_printf(bio_err, "No signer certificate specified\n");

            goto opthelp;

        }

        signerfile = NULL;

        keyfile = NULL;

    } else if (operation == SMIME_DECRYPT) {

        if (recipfile == NULL && keyfile == NULL) {

            BIO_printf(bio_err,

                       "No recipient certificate or key specified\n");

            goto opthelp;

        }

    } else if (operation == SMIME_ENCRYPT) {

        if (argc == 0) {

            BIO_printf(bio_err, "No recipient(s) certificate(s) specified\n");

            goto opthelp;

        }

    } else if (!operation) {

        goto opthelp;

    }

    if (!app_passwd(passinarg, NULL, &passin, NULL)) {

        BIO_printf(bio_err, "Error getting password\n");

        goto end;

    }

    ret = 2;

    if (!(operation & SMIME_SIGNERS))

        flags &= ~PKCS7_DETACHED;

    if (!(operation & SMIME_OP)) {

        if (flags & PKCS7_BINARY)

            outformat = FORMAT_BINARY;

    }

    if (!(operation & SMIME_IP)) {

        if (flags & PKCS7_BINARY)

            informat = FORMAT_BINARY;

    }

    if (operation == SMIME_ENCRYPT) {

        if (cipher == NULL) {

#ifndef OPENSSL_NO_DES

            cipher = EVP_des_ede3_cbc();

#else

            BIO_printf(bio_err, "No cipher selected\n");

            goto end;

#endif

        }

        encerts = sk_X509_new_null();

        if (encerts == NULL)

            goto end;

        while (*argv != NULL) {

            cert = load_cert(*argv, FORMAT_PEM,

                             "recipient certificate file");

            if (cert == NULL)

                goto end;

            sk_X509_push(encerts, cert);

            cert = NULL;

            argv++;

        }

    }

    if (certfile != NULL) {

        if (!load_certs(certfile, &other, FORMAT_PEM, NULL,

                        "certificate file")) {

            ERR_print_errors(bio_err);

            goto end;

        }

    }

    if (recipfile != NULL && (operation == SMIME_DECRYPT)) {

        if ((recip = load_cert(recipfile, FORMAT_PEM,

                               "recipient certificate file")) == NULL) {

            ERR_print_errors(bio_err);

            goto end;

        }

    }

    if (operation == SMIME_DECRYPT) {

        if (keyfile == NULL)

            keyfile = recipfile;

    } else if (operation == SMIME_SIGN) {

        if (keyfile == NULL)

            keyfile = signerfile;

    } else {

        keyfile = NULL;

    }

    if (keyfile != NULL) {

        key = load_key(keyfile, keyform, 0, passin, e, "signing key file");

        if (key == NULL)

            goto end;

    }

    in = bio_open_default(infile, 'r', informat);

    if (in == NULL)

        goto end;

    if (operation & SMIME_IP) {

        if (informat == FORMAT_SMIME) {

            p7 = SMIME_read_PKCS7(in, &indata);

        } else if (informat == FORMAT_PEM) {

            p7 = PEM_read_bio_PKCS7(in, NULL, NULL, NULL);

        } else if (informat == FORMAT_ASN1) {

            p7 = d2i_PKCS7_bio(in, NULL);

        } else {

            BIO_printf(bio_err, "Bad input format for PKCS#7 file\n");

            goto end;

        }

        if (p7 == NULL) {

            BIO_printf(bio_err, "Error reading S/MIME message\n");

            goto end;

        }

        if (contfile != NULL) {

            BIO_free(indata);

            if ((indata = BIO_new_file(contfile, "rb")) == NULL) {

                BIO_printf(bio_err, "Can't read content file %s\n", contfile);

                goto end;

            }

        }

    }

    out = bio_open_default(outfile, 'w', outformat);

    if (out == NULL)

        goto end;

    if (operation == SMIME_VERIFY) {

        if ((store = setup_verify(CAfile, CApath, noCAfile, noCApath)) == NULL)

            goto end;

        X509_STORE_set_verify_cb(store, smime_cb);

        if (vpmtouched)

            X509_STORE_set1_param(store, vpm);

    }

    ret = 3;

    if (operation == SMIME_ENCRYPT) {

        if (indef)

            flags |= PKCS7_STREAM;

        p7 = PKCS7_encrypt(encerts, in, cipher, flags);

    } else if (operation & SMIME_SIGNERS) {

        int i;

        /*

         * If detached data content we only enable streaming if S/MIME output

         * format.

         */

        if (operation == SMIME_SIGN) {

            if (flags & PKCS7_DETACHED) {

                if (outformat == FORMAT_SMIME)

                    flags |= PKCS7_STREAM;

            } else if (indef) {

                flags |= PKCS7_STREAM;

            }

            flags |= PKCS7_PARTIAL;

            p7 = PKCS7_sign(NULL, NULL, other, in, flags);

            if (p7 == NULL)

                goto end;

            if (flags & PKCS7_NOCERTS) {

                for (i = 0; i < sk_X509_num(other); i++) {

                    X509 *x = sk_X509_value(other, i);

                    PKCS7_add_certificate(p7, x);

                }

            }

        } else {

            flags |= PKCS7_REUSE_DIGEST;

        }

        for (i = 0; i < sk_OPENSSL_STRING_num(sksigners); i++) {

            signerfile = sk_OPENSSL_STRING_value(sksigners, i);

            keyfile = sk_OPENSSL_STRING_value(skkeys, i);

            signer = load_cert(signerfile, FORMAT_PEM,

                               "signer certificate");

            if (signer == NULL)

                goto end;

            key = load_key(keyfile, keyform, 0, passin, e, "signing key file");

            if (key == NULL)

                goto end;

            if (!PKCS7_sign_add_signer(p7, signer, key, sign_md, flags))

                goto end;

            X509_free(signer);

            signer = NULL;

            EVP_PKEY_free(key);

            key = NULL;

        }

        /* If not streaming or resigning finalize structure */

        if ((operation == SMIME_SIGN) && !(flags & PKCS7_STREAM)) {

            if (!PKCS7_final(p7, in, flags))

                goto end;

        }

    }

    if (p7 == NULL) {

        BIO_printf(bio_err, "Error creating PKCS#7 structure\n");

        goto end;

    }

    ret = 4;

    if (operation == SMIME_DECRYPT) {

        if (!PKCS7_decrypt(p7, key, recip, out, flags)) {

            BIO_printf(bio_err, "Error decrypting PKCS#7 structure\n");

            goto end;

        }

    } else if (operation == SMIME_VERIFY) {

        STACK_OF(X509) *signers;

        if (PKCS7_verify(p7, other, store, indata, out, flags))

            BIO_printf(bio_err, "Verification successful\n");

        else {

            BIO_printf(bio_err, "Verification failure\n");

            goto end;

        }

        signers = PKCS7_get0_signers(p7, other, flags);

        if (!save_certs(signerfile, signers)) {

            BIO_printf(bio_err, "Error writing signers to %s\n", signerfile);

            ret = 5;

            goto end;

        }

        sk_X509_free(signers);

    } else if (operation == SMIME_PK7OUT) {

        PEM_write_bio_PKCS7(out, p7);

    } else {

        if (to)

            BIO_printf(out, "To: %s%s", to, mime_eol);

        if (from)

            BIO_printf(out, "From: %s%s", from, mime_eol);

        if (subject)

            BIO_printf(out, "Subject: %s%s", subject, mime_eol);

        if (outformat == FORMAT_SMIME) {

            if (operation == SMIME_RESIGN)

                rv = SMIME_write_PKCS7(out, p7, indata, flags);

            else

                rv = SMIME_write_PKCS7(out, p7, in, flags);

        } else if (outformat == FORMAT_PEM) {

            rv = PEM_write_bio_PKCS7_stream(out, p7, in, flags);

        } else if (outformat == FORMAT_ASN1) {

            rv = i2d_PKCS7_bio_stream(out, p7, in, flags);

        } else {

            BIO_printf(bio_err, "Bad output format for PKCS#7 file\n");

            goto end;

        }

        if (rv == 0) {

            BIO_printf(bio_err, "Error writing output\n");

            ret = 3;

            goto end;

        }

    }

    ret = 0;

 end:

    if (ret)

        ERR_print_errors(bio_err);

    sk_X509_pop_free(encerts, X509_free);

    sk_X509_pop_free(other, X509_free);

    X509_VERIFY_PARAM_free(vpm);

    sk_OPENSSL_STRING_free(sksigners);

    sk_OPENSSL_STRING_free(skkeys);

    X509_STORE_free(store);

    X509_free(cert);

    X509_free(recip);

    X509_free(signer);

    EVP_PKEY_free(key);

    PKCS7_free(p7);

    release_engine(e);

    BIO_free(in);

    BIO_free(indata);

    BIO_free_all(out);

    OPENSSL_free(passin);

    return ret;

}

static int save_certs(char *signerfile, STACK_OF(X509) *signers)

{

    int i;

    BIO *tmp;

    if (signerfile == NULL)

        return 1;

    tmp = BIO_new_file(signerfile, "w");

    if (tmp == NULL)

        return 0;

    for (i = 0; i < sk_X509_num(signers); i++)

        PEM_write_bio_X509(tmp, sk_X509_value(signers, i));

    BIO_free(tmp);

    return 1;

}

/* Minimal callback just to output policy info (if any) */

static int smime_cb(int ok, X509_STORE_CTX *ctx)

{

    int error;

    error = X509_STORE_CTX_get_error(ctx);

    if ((error != X509_V_ERR_NO_EXPLICIT_POLICY)

        && ((error != X509_V_OK) || (ok != 2)))

        return ok;

    policies_print(ctx);

    return ok;

}