/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"

#include "settings.h"

#include "settings-parser.h"

#include "iostream-ssl.h"

#undef DEF

#define DEF(type, name) \

  SETTING_DEFINE_STRUCT_##type(#name, name, struct ssl_settings)

static bool

ssl_settings_check(void *_set, pool_t pool, const char **error_r);

static bool

ssl_server_settings_check(void *_set, pool_t pool, const char **error_r);

static const struct setting_define ssl_setting_defines[] = {

  { .type = SET_FILTER_NAME, .key = "ssl_client", },

  { .type = SET_FILTER_NAME, .key = "ssl_server", },

  DEF(FILE, ssl_client_ca_file),

  DEF(STR, ssl_client_ca_dir),

  DEF(FILE, ssl_client_cert_file),

  DEF(FILE, ssl_client_key_file),

  DEF(STR, ssl_client_key_password),

  DEF(STR, ssl_cipher_list),

  DEF(STR, ssl_cipher_suites),

  DEF(STR, ssl_curve_list),

  DEF(STR, ssl_min_protocol),

  DEF(STR, ssl_crypto_device),

  DEF(BOOL, ssl_client_require_valid_cert),

  DEF(STR, ssl_options), /* parsed as a string to set bools */

  DEF(STR, ssl_peer_certificate_fingerprint_hash),

  SETTING_DEFINE_LIST_END

};

const struct ssl_settings ssl_default_settings = {

  .ssl_client_ca_file = "",

  .ssl_client_ca_dir = "",

  .ssl_client_cert_file = "",

  .ssl_client_key_file = "",

  .ssl_client_key_password = "",

  .ssl_cipher_list = "ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH",

  .ssl_cipher_suites = "", /* Use TLS library provided value */

  .ssl_curve_list = "",

  .ssl_min_protocol = "TLSv1.2",

  .ssl_crypto_device = "",

  .ssl_client_require_valid_cert = TRUE,

  .ssl_options = "",

  .ssl_peer_certificate_fingerprint_hash = "",

};

static const struct setting_keyvalue ssl_default_settings_keyvalue[] = {

  { "ssl_client/ssl_cipher_list", "" },

  { NULL, NULL }

};

const struct setting_parser_info ssl_setting_parser_info = {

  .name = "ssl",

  .defines = ssl_setting_defines,

  .defaults = &ssl_default_settings,

  .default_settings = ssl_default_settings_keyvalue,

  .pool_offset1 = 1 + offsetof(struct ssl_settings, pool),

  .struct_size = sizeof(struct ssl_settings),

  .check_func = ssl_settings_check

};

#undef DEF

#define DEF(type, name) \

  SETTING_DEFINE_STRUCT_##type(#name, name, struct ssl_server_settings)

static const struct setting_define ssl_server_setting_defines[] = {

  DEF(ENUM, ssl),

  DEF(FILE, ssl_server_ca_file),

  DEF(FILE, ssl_server_cert_file),

  DEF(FILE, ssl_server_key_file),

  DEF(FILE, ssl_server_alt_cert_file),

  DEF(FILE, ssl_server_alt_key_file),

  DEF(STR, ssl_server_key_password),

  DEF(FILE, ssl_server_dh_file),

  DEF(STR, ssl_server_cert_username_field),

  DEF(ENUM, ssl_server_prefer_ciphers),

  DEF(BOOL, ssl_server_require_crl),

  DEF(ENUM, ssl_server_request_client_cert),

  SETTING_DEFINE_LIST_END

};

static const struct ssl_server_settings ssl_server_default_settings = {

  .ssl = "yes:no:required",

  .ssl_server_ca_file = "",

  .ssl_server_cert_file = "",

  .ssl_server_key_file = "",

  .ssl_server_alt_cert_file = "",

  .ssl_server_alt_key_file = "",

  .ssl_server_key_password = "",

  .ssl_server_dh_file = "",

  .ssl_server_cert_username_field = "commonName",

  .ssl_server_prefer_ciphers = "client:server",

  .ssl_server_require_crl = TRUE,

  .ssl_server_request_client_cert = "no:yes:any-cert",

};

const struct setting_parser_info ssl_server_setting_parser_info = {

  .name = "ssl_server",

  .defines = ssl_server_setting_defines,

  .defaults = &ssl_server_default_settings,

  .pool_offset1 = 1 + offsetof(struct ssl_server_settings, pool),

  .struct_size = sizeof(struct ssl_server_settings),

  .check_func = ssl_server_settings_check,

};

/* <settings checks> */

static bool

ssl_settings_check(void *_set, pool_t pool ATTR_UNUSED,

       const char **error_r)

{

  struct ssl_settings *set = _set;

  if (settings_get_config_binary() != SETTINGS_BINARY_OTHER) {

    const char *proto = t_str_ucase(set->ssl_min_protocol);

    if (*proto == '\0') {

      *error_r = "ssl_min_protocol cannot be empty";

      return FALSE;

    }

    if (strstr(proto, "ANY") != NULL)

      i_warning("ssl_min_protocol=ANY is used - This is "

          "insecure and intended only for testing");

  }

  /* Now explode the ssl_options string into individual flags */

  /* First set them all to defaults */

  set->parsed_opts.compression = FALSE;

  set->parsed_opts.tickets = TRUE;

  /* Then modify anything specified in the string */

  const char **opts = t_strsplit_spaces(set->ssl_options, ", ");

  const char *opt;

  while ((opt = *opts++) != NULL) {

    if (strcasecmp(opt, "compression") == 0) {

      set->parsed_opts.compression = TRUE;

    } else if (strcasecmp(opt, "no_ticket") == 0) {

      set->parsed_opts.tickets = FALSE;

    } else {

      *error_r = t_strdup_printf("ssl_options: unknown flag: '%s'",

               opt);

      return FALSE;

    }

  }

  /* Hashing algorithms considered unsafe for

     fingerprinting purposes. */

  static const char *const unsafe_hash_algos[] = {

    "md4", "md5", "sha1", "rmd160", "sm3", NULL

  };

  if (str_array_icase_find(unsafe_hash_algos,

         set->ssl_peer_certificate_fingerprint_hash)) {

    *error_r = t_strdup_printf(

        "ssl_peer_certificate_fingerprint_hash: "

        "Unsafe hash algorithm '%s' used",

        set->ssl_peer_certificate_fingerprint_hash);

    return FALSE;

  }

  return TRUE;

}

static bool

ssl_server_settings_check(void *_set, pool_t pool ATTR_UNUSED,

        const char **error_r)

{

  struct ssl_server_settings *set = _set;

  if (strcmp(set->ssl, "no") == 0) {

    /* disabled */

    return TRUE;

  }

  if (strcmp(set->ssl_server_request_client_cert, "no") == 0) {

    set->parsed_opts.request_client_cert = FALSE;

    set->parsed_opts.verify_client_cert = FALSE;

  } else if (strcmp(set->ssl_server_request_client_cert, "yes") == 0) {

    set->parsed_opts.request_client_cert = TRUE;

    set->parsed_opts.verify_client_cert = TRUE;

  } else if (strcmp(set->ssl_server_request_client_cert, "any-cert") == 0) {

    set->parsed_opts.request_client_cert = TRUE;

    set->parsed_opts.verify_client_cert = FALSE;

  }

  if (set->parsed_opts.request_client_cert &&

      set->parsed_opts.verify_client_cert &&

      *set->ssl_server_ca_file == '\0') {

    *error_r = "ssl_server_request_client_cert=yes, but ssl_server_ca_file not provided";

    return FALSE;

  }

  return TRUE;

}

/* </settings checks> */

int ssl_client_settings_get(struct event *event,

          const struct ssl_settings **set_r,

          const char **error_r)

{

  event = event_create(event);

  settings_event_add_filter_name(event, "ssl_client");

  int ret = settings_get(event, &ssl_setting_parser_info, 0,

             set_r, error_r);

  event_unref(&event);

  return ret;

}

int ssl_server_settings_get(struct event *event,

          const struct ssl_settings **set_r,

          const struct ssl_server_settings **server_set_r,

          const char **error_r)

{

  event = event_create(event);

  settings_event_add_filter_name(event, "ssl_server");

  int ret = settings_get(event, &ssl_setting_parser_info, 0,

             set_r, error_r);

  if (ret == 0) {

    ret = settings_get(event, &ssl_server_setting_parser_info, 0,

           server_set_r, error_r);

    if (ret < 0)

      settings_free(*set_r);

  }

  event_unref(&event);

  return ret;

}

static struct ssl_iostream_settings *

ssl_common_settings_to_iostream_set(const struct ssl_settings *ssl_set)

{

  struct ssl_iostream_settings *set;

  pool_t pool = pool_alloconly_create("ssl iostream settings", 512);

  set = p_new(pool, struct ssl_iostream_settings, 1);

  pool_add_external_ref(pool, ssl_set->pool);

  set->pool = pool;

  set->min_protocol = ssl_set->ssl_min_protocol;

  set->cipher_list = ssl_set->ssl_cipher_list;

  set->ciphersuites = ssl_set->ssl_cipher_suites;

  set->crypto_device = ssl_set->ssl_crypto_device;

  set->compression = ssl_set->parsed_opts.compression;

  set->tickets = ssl_set->parsed_opts.tickets;

  set->curve_list = ssl_set->ssl_curve_list;

  set->cert_hash_algo = ssl_set->ssl_peer_certificate_fingerprint_hash;

  return set;

}

void ssl_client_settings_to_iostream_set(

  const struct ssl_settings *ssl_set,

  const struct ssl_iostream_settings **set_r)

{

  struct ssl_iostream_settings *set =

    ssl_common_settings_to_iostream_set(ssl_set);

  settings_file_get(ssl_set->ssl_client_ca_file,

        set->pool, &set->ca);

  set->ca_dir = ssl_set->ssl_client_ca_dir;

  settings_file_get(ssl_set->ssl_client_cert_file,

        set->pool, &set->cert.cert);

  settings_file_get(ssl_set->ssl_client_key_file,

        set->pool, &set->cert.key);

  set->cert.key_password = ssl_set->ssl_client_key_password;

  set->verify_remote_cert = ssl_set->ssl_client_require_valid_cert;

  set->allow_invalid_cert = !set->verify_remote_cert;

  /* client-side CRL checking not supported currently */

  set->skip_crl_check = TRUE;

  *set_r = set;

}

void ssl_server_settings_to_iostream_set(

  const struct ssl_settings *ssl_set,

  const struct ssl_server_settings *ssl_server_set,

  const struct ssl_iostream_settings **set_r)

{

  struct ssl_iostream_settings *set =

    ssl_common_settings_to_iostream_set(ssl_set);

  pool_add_external_ref(set->pool, ssl_server_set->pool);

  settings_file_get(ssl_server_set->ssl_server_ca_file, set->pool, &set->ca);

  settings_file_get(ssl_server_set->ssl_server_cert_file,

        set->pool, &set->cert.cert);

  settings_file_get(ssl_server_set->ssl_server_key_file,

        set->pool, &set->cert.key);

  set->cert.key_password = ssl_server_set->ssl_server_key_password;

  if (ssl_server_set->ssl_server_alt_cert_file != NULL &&

      *ssl_server_set->ssl_server_alt_cert_file != '\0') {

    settings_file_get(ssl_server_set->ssl_server_alt_cert_file,

          set->pool, &set->alt_cert.cert);

    settings_file_get(ssl_server_set->ssl_server_alt_key_file,

          set->pool, &set->alt_cert.key);

    set->alt_cert.key_password =

      ssl_server_set->ssl_server_key_password;

  }

  settings_file_get(ssl_server_set->ssl_server_dh_file,

        set->pool, &set->dh);

  set->cert_username_field =

    ssl_server_set->ssl_server_cert_username_field;

  set->prefer_server_ciphers =

    strcmp(ssl_server_set->ssl_server_prefer_ciphers, "server") == 0;

  set->verify_remote_cert = ssl_server_set->parsed_opts.request_client_cert;

  set->allow_invalid_cert = !ssl_server_set->parsed_opts.verify_client_cert ||

          !set->verify_remote_cert;

  /* ssl_server_require_crl is used only for checking client-provided SSL

     certificate's CRL. */

  set->skip_crl_check = !ssl_server_set->ssl_server_require_crl;

  *set_r = set;

}