crypto/x509/algorithm.c

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#include <openssl/x509.h>

#include <openssl/asn1.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/obj.h>

#include "internal.h"

// Restrict the digests that are allowed in X509 certificates
static int x509_digest_nid_ok(const int digest_nid) {
  switch (digest_nid) {
    case NID_md4:
    case NID_md5:
      return 0;
  }
  return 1;
}

int x509_digest_sign_algorithm(EVP_MD_CTX *ctx, X509_ALGOR *algor) {
  EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx->pctx);
  if (pkey == NULL) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_CONTEXT_NOT_INITIALISED);
    return 0;
  }

  if (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) {
    int pad_mode;
    if (!EVP_PKEY_CTX_get_rsa_padding(ctx->pctx, &pad_mode)) {
      return 0;
    }
    // RSA-PSS has special signature algorithm logic.
    if (pad_mode == RSA_PKCS1_PSS_PADDING) {
      return x509_rsa_ctx_to_pss(ctx, algor);
    }
  }

  if (EVP_PKEY_id(pkey) == EVP_PKEY_ED25519) {
    return X509_ALGOR_set0(algor, OBJ_nid2obj(NID_ED25519), V_ASN1_UNDEF, NULL);
  }

  // Default behavior: look up the OID for the algorithm/hash pair and encode
  // that.
  const EVP_MD *digest = EVP_MD_CTX_md(ctx);
  if (digest == NULL) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_CONTEXT_NOT_INITIALISED);
    return 0;
  }

  const int digest_nid = EVP_MD_type(digest);
  int sign_nid;
  if (!x509_digest_nid_ok(digest_nid) ||
      !OBJ_find_sigid_by_algs(&sign_nid, digest_nid, EVP_PKEY_id(pkey))) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DIGEST_AND_KEY_TYPE_NOT_SUPPORTED);
    return 0;
  }

  // RSA signature algorithms include an explicit NULL parameter. Others omit
  // it.
  int paramtype =
      (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) ? V_ASN1_NULL : V_ASN1_UNDEF;
  X509_ALGOR_set0(algor, OBJ_nid2obj(sign_nid), paramtype, NULL);
  return 1;
}

int x509_digest_verify_init(EVP_MD_CTX *ctx, const X509_ALGOR *sigalg,
                            EVP_PKEY *pkey) {
  // Convert the signature OID into digest and public key OIDs.
  int sigalg_nid = OBJ_obj2nid(sigalg->algorithm);
  int digest_nid, pkey_nid;
  if (!OBJ_find_sigid_algs(sigalg_nid, &digest_nid, &pkey_nid)) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
    return 0;
  }

  // Check the public key OID matches the public key type.
  if (pkey_nid != EVP_PKEY_id(pkey)) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_PUBLIC_KEY_TYPE);
    return 0;
  }

  // Check for permitted digest algorithms
  if (!x509_digest_nid_ok(digest_nid)) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DIGEST_AND_KEY_TYPE_NOT_SUPPORTED);
    return 0;
  }

  // NID_undef signals that there are custom parameters to set.
  if (digest_nid == NID_undef) {
    if (sigalg_nid == NID_rsassaPss) {
      return x509_rsa_pss_to_ctx(ctx, sigalg, pkey);
    }
    if (sigalg_nid == NID_ED25519) {
      if (sigalg->parameter != NULL) {
        OPENSSL_PUT_ERROR(X509, X509_R_INVALID_PARAMETER);
        return 0;
      }
      return EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey);
    }
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
    return 0;
  }

  // The parameter should be an explicit NULL for RSA and omitted for ECDSA. For
  // compatibility, we allow either for both algorithms. See b/167375496.
  //
  // TODO(davidben): Chromium's verifier allows both forms for RSA, but enforces
  // ECDSA more strictly. Align with Chromium and add a flag for b/167375496.
  if (sigalg->parameter != NULL && sigalg->parameter->type != V_ASN1_NULL) {
    OPENSSL_PUT_ERROR(X509, X509_R_INVALID_PARAMETER);
    return 0;
  }

  // Otherwise, initialize with the digest from the OID.
  const EVP_MD *digest = EVP_get_digestbynid(digest_nid);
  if (digest == NULL) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
    return 0;
  }

  return EVP_DigestVerifyInit(ctx, NULL, digest, NULL, pkey);
}