// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include <assert.h>

#include <limits.h>

#include <stdio.h>

#include <openssl/asn1.h>

#include <openssl/asn1t.h>

#include <openssl/bytestring.h>

#include <openssl/evp.h>

#include <openssl/mem.h>

#include <openssl/obj.h>

#include <openssl/pool.h>

#include <openssl/x509.h>

#include "../asn1/internal.h"

#include "../bytestring/internal.h"

#include "../evp/internal.h"

#include "../internal.h"

#include "internal.h"

static CRYPTO_EX_DATA_CLASS g_ex_data_class = CRYPTO_EX_DATA_CLASS_INIT;

static constexpr CBS_ASN1_TAG kVersionTag =

    CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 0;

static constexpr CBS_ASN1_TAG kIssuerUIDTag = CBS_ASN1_CONTEXT_SPECIFIC | 1;

static constexpr CBS_ASN1_TAG kSubjectUIDTag = CBS_ASN1_CONTEXT_SPECIFIC | 2;

static constexpr CBS_ASN1_TAG kExtensionsTag =

    CBS_ASN1_CONSTRUCTED | CBS_ASN1_CONTEXT_SPECIFIC | 3;

X509 *X509_new(void) {

  bssl::UniquePtr<X509> ret(

      reinterpret_cast<X509 *>(OPENSSL_zalloc(sizeof(X509))));

  if (ret == nullptr) {

    return nullptr;

  }

  ret->references = 1;

  ret->ex_pathlen = -1;

  ret->version = X509_VERSION_1;

  asn1_string_init(&ret->serialNumber, V_ASN1_INTEGER);

  x509_algor_init(&ret->tbs_sig_alg);

  x509_name_init(&ret->issuer);

  asn1_string_init(&ret->notBefore, -1);

  asn1_string_init(&ret->notAfter, -1);

  x509_name_init(&ret->subject);

  x509_pubkey_init(&ret->key);

  x509_algor_init(&ret->sig_alg);

  asn1_string_init(&ret->signature, V_ASN1_BIT_STRING);

  CRYPTO_new_ex_data(&ret->ex_data);

  CRYPTO_MUTEX_init(&ret->lock);

  return ret.release();

}

void X509_free(X509 *x509) {

  if (x509 == nullptr ||

      !CRYPTO_refcount_dec_and_test_zero(&x509->references)) {

    return;

  }

  CRYPTO_free_ex_data(&g_ex_data_class, &x509->ex_data);

  asn1_string_cleanup(&x509->serialNumber);

  x509_algor_cleanup(&x509->tbs_sig_alg);

  x509_name_cleanup(&x509->issuer);

  asn1_string_cleanup(&x509->notBefore);

  asn1_string_cleanup(&x509->notAfter);

  x509_name_cleanup(&x509->subject);

  x509_pubkey_cleanup(&x509->key);

  ASN1_BIT_STRING_free(x509->issuerUID);

  ASN1_BIT_STRING_free(x509->subjectUID);

  sk_X509_EXTENSION_pop_free(x509->extensions, X509_EXTENSION_free);

  x509_algor_cleanup(&x509->sig_alg);

  asn1_string_cleanup(&x509->signature);

  CRYPTO_BUFFER_free(x509->buf);

  ASN1_OCTET_STRING_free(x509->skid);

  AUTHORITY_KEYID_free(x509->akid);

  CRL_DIST_POINTS_free(x509->crldp);

  GENERAL_NAMES_free(x509->altname);

  NAME_CONSTRAINTS_free(x509->nc);

  X509_CERT_AUX_free(x509->aux);

  CRYPTO_MUTEX_cleanup(&x509->lock);

  OPENSSL_free(x509);

}

X509 *X509_parse_with_algorithms(CRYPTO_BUFFER *buf,

                                 const EVP_PKEY_ALG *const *algs,

                                 size_t num_algs) {

  bssl::UniquePtr<X509> ret(X509_new());

  if (ret == nullptr) {

    return nullptr;

  }

  // Save the buffer to cache the original encoding.

  ret->buf = bssl::UpRef(buf).release();

  // Parse the Certificate.

  CBS cbs, cert, tbs;

  CRYPTO_BUFFER_init_CBS(buf, &cbs);

  if (!CBS_get_asn1(&cbs, &cert, CBS_ASN1_SEQUENCE) ||  //

      CBS_len(&cbs) != 0 ||

      // Bound the length to comfortably fit in an int. Lengths in this

      // module often omit overflow checks.

      CBS_len(&cert) > INT_MAX / 2 ||

      !CBS_get_asn1(&cert, &tbs, CBS_ASN1_SEQUENCE) ||

      !x509_parse_algorithm(&cert, &ret->sig_alg) ||

      // For just the signature field, we accept non-minimal BER lengths, though

      // not indefinite-length encoding. See b/18228011.

      //

      // TODO(crbug.com/boringssl/354): Switch the affected callers to convert

      // the certificate before parsing and then remove this workaround.

      !asn1_parse_bit_string_with_bad_length(&cert, &ret->signature) ||

      CBS_len(&cert) != 0) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return nullptr;

  }

  // Parse the TBSCertificate.

  if (CBS_peek_asn1_tag(&tbs, kVersionTag)) {

    CBS wrapper;

    uint64_t version;

    if (!CBS_get_asn1(&tbs, &wrapper, kVersionTag) ||

        !CBS_get_asn1_uint64(&wrapper, &version) ||  //

        CBS_len(&wrapper) != 0) {

      OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

      return nullptr;

    }

    // The version must be one of v1(0), v2(1), or v3(2).

    // TODO(https://crbug.com/42290225): Also reject |X509_VERSION_1|. v1 is

    // DEFAULT, so DER requires it be omitted.

    if (version != X509_VERSION_1 && version != X509_VERSION_2 &&

        version != X509_VERSION_3) {

      OPENSSL_PUT_ERROR(X509, X509_R_INVALID_VERSION);

      return nullptr;

    }

    ret->version = static_cast<uint8_t>(version);

  } else {

    ret->version = X509_VERSION_1;

  }

  CBS validity;

  if (!asn1_parse_integer(&tbs, &ret->serialNumber, /*tag=*/0) ||

      !x509_parse_algorithm(&tbs, &ret->tbs_sig_alg) ||

      !x509_parse_name(&tbs, &ret->issuer) ||

      !CBS_get_asn1(&tbs, &validity, CBS_ASN1_SEQUENCE) ||

      !asn1_parse_time(&validity, &ret->notBefore,

                       /*allow_utc_timezone_offset=*/1) ||

      !asn1_parse_time(&validity, &ret->notAfter,

                       /*allow_utc_timezone_offset=*/1) ||

      CBS_len(&validity) != 0 ||  //

      !x509_parse_name(&tbs, &ret->subject) ||

      !x509_parse_public_key(&tbs, &ret->key, bssl::Span(algs, num_algs))) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return nullptr;

  }

  // Per RFC 5280, section 4.1.2.8, these fields require v2 or v3:

  if (ret->version >= X509_VERSION_2 &&

      CBS_peek_asn1_tag(&tbs, kIssuerUIDTag)) {

    ret->issuerUID = ASN1_BIT_STRING_new();

    if (ret->issuerUID == nullptr ||

        !asn1_parse_bit_string(&tbs, ret->issuerUID, kIssuerUIDTag)) {

      return nullptr;

    }

  }

  if (ret->version >= X509_VERSION_2 &&

      CBS_peek_asn1_tag(&tbs, kSubjectUIDTag)) {

    ret->subjectUID = ASN1_BIT_STRING_new();

    if (ret->subjectUID == nullptr ||

        !asn1_parse_bit_string(&tbs, ret->subjectUID, kSubjectUIDTag)) {

      return nullptr;

    }

  }

  // Per RFC 5280, section 4.1.2.9, extensions require v3:

  if (ret->version >= X509_VERSION_3 &&

      CBS_peek_asn1_tag(&tbs, kExtensionsTag)) {

    CBS wrapper;

    if (!CBS_get_asn1(&tbs, &wrapper, kExtensionsTag)) {

      OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

      return nullptr;

    }

    // TODO(crbug.com/442221114, crbug.com/42290219): Empty extension lists

    // should be rejected. Extensions is a SEQUENCE SIZE (1..MAX), so it cannot

    // be empty. An empty extensions list is encoded by omitting the OPTIONAL

    // field. libpki already rejects this.

    const uint8_t *p = CBS_data(&wrapper);

    ret->extensions = d2i_X509_EXTENSIONS(nullptr, &p, CBS_len(&wrapper));

    if (ret->extensions == nullptr ||

        p != CBS_data(&wrapper) + CBS_len(&wrapper)) {

      OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

      return nullptr;

    }

  }

  if (CBS_len(&tbs) != 0) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return nullptr;

  }

  return ret.release();

}

X509 *X509_parse_from_buffer(CRYPTO_BUFFER *buf) {

  auto algs = bssl::GetDefaultEVPAlgorithms();

  return X509_parse_with_algorithms(buf, algs.data(), algs.size());

}

static bssl::UniquePtr<X509> x509_parse(CBS *cbs) {

  CBS cert;

  if (!CBS_get_asn1_element(cbs, &cert, CBS_ASN1_SEQUENCE)) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return nullptr;

  }

  bssl::UniquePtr<CRYPTO_BUFFER> buf(CRYPTO_BUFFER_new_from_CBS(&cert, nullptr));

  if (buf == nullptr) {

    return nullptr;

  }

  return bssl::UniquePtr<X509>(X509_parse_from_buffer(buf.get()));

}

int x509_marshal_tbs_cert(CBB *cbb, const X509 *x509) {

  if (x509->buf != nullptr) {

    // Replay the saved TBSCertificate from the |CRYPTO_BUFFER|, to verify

    // exactly what we parsed. The |CRYPTO_BUFFER| contains the full

    // Certificate, so we need to find the TBSCertificate portion.

    CBS cbs, cert, tbs;

    CRYPTO_BUFFER_init_CBS(x509->buf, &cbs);

    if (!CBS_get_asn1(&cbs, &cert, CBS_ASN1_SEQUENCE) ||

        !CBS_get_asn1_element(&cert, &tbs, CBS_ASN1_SEQUENCE)) {

      // This should be impossible.

      OPENSSL_PUT_ERROR(X509, ERR_R_INTERNAL_ERROR);

      return 0;

    }

    return CBB_add_bytes(cbb, CBS_data(&tbs), CBS_len(&tbs));

  }

  // No saved TBSCertificate encoding. Encode it anew.

  CBB tbs, version, validity, extensions;

  if (!CBB_add_asn1(cbb, &tbs, CBS_ASN1_SEQUENCE)) {

    return 0;

  }

  if (x509->version != X509_VERSION_1) {

    if (!CBB_add_asn1(&tbs, &version, kVersionTag) ||

        !CBB_add_asn1_uint64(&version, x509->version)) {

      return 0;

    }

  }

  if (!asn1_marshal_integer(&tbs, &x509->serialNumber, /*tag=*/0) ||

      !x509_marshal_algorithm(&tbs, &x509->tbs_sig_alg) ||

      !x509_marshal_name(&tbs, &x509->issuer) ||

      !CBB_add_asn1(&tbs, &validity, CBS_ASN1_SEQUENCE) ||

      !asn1_marshal_time(&validity, &x509->notBefore) ||

      !asn1_marshal_time(&validity, &x509->notAfter) ||

      !x509_marshal_name(&tbs, &x509->subject) ||

      !x509_marshal_public_key(&tbs, &x509->key) ||

      (x509->issuerUID != nullptr &&

       !asn1_marshal_bit_string(&tbs, x509->issuerUID, kIssuerUIDTag)) ||

      (x509->subjectUID != nullptr &&

       !asn1_marshal_bit_string(&tbs, x509->subjectUID, kSubjectUIDTag))) {

    return 0;

  }

  if (x509->extensions != nullptr) {

    int len = i2d_X509_EXTENSIONS(x509->extensions, nullptr);

    uint8_t *out;

    if (len <= 0 ||  //

        !CBB_add_asn1(&tbs, &extensions, kExtensionsTag) ||

        !CBB_add_space(&extensions, &out, len) ||

        i2d_X509_EXTENSIONS(x509->extensions, &out) != len) {

      return 0;

    }

  }

  return CBB_flush(cbb);

}

static int x509_marshal(CBB *cbb, const X509 *x509) {

  CBB cert;

  return CBB_add_asn1(cbb, &cert, CBS_ASN1_SEQUENCE) &&

         x509_marshal_tbs_cert(&cert, x509) &&

         x509_marshal_algorithm(&cert, &x509->sig_alg) &&

         asn1_marshal_bit_string(&cert, &x509->signature, /*tag=*/0) &&

         CBB_flush(cbb);

}

X509 *d2i_X509(X509 **out, const uint8_t **inp, long len) {

  return bssl::D2IFromCBS(out, inp, len, x509_parse);

}

int i2d_X509(const X509 *x509, uint8_t **outp) {

  if (x509 == nullptr) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_MISSING_VALUE);

    return -1;

  }

  return bssl::I2DFromCBB(

      /*initial_capacity=*/256, outp,

      [&](CBB *cbb) -> bool { return x509_marshal(cbb, x509); });

}

static int x509_new_cb(ASN1_VALUE **pval, const ASN1_ITEM *it) {

  *pval = (ASN1_VALUE *)X509_new();

  return *pval != nullptr;

}

static void x509_free_cb(ASN1_VALUE **pval, const ASN1_ITEM *it) {

  X509_free((X509 *)*pval);

  *pval = nullptr;

}

static int x509_parse_cb(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,

                         int opt) {

  if (opt && !CBS_peek_asn1_tag(cbs, CBS_ASN1_SEQUENCE)) {

    return 1;

  }

  bssl::UniquePtr<X509> ret = x509_parse(cbs);

  if (ret == nullptr) {

    return 0;

  }

  X509_free((X509 *)*pval);

  *pval = (ASN1_VALUE *)ret.release();

  return 1;

}

static int x509_i2d_cb(ASN1_VALUE **pval, unsigned char **out,

                       const ASN1_ITEM *it) {

  return i2d_X509((X509 *)*pval, out);

}

static const ASN1_EXTERN_FUNCS x509_extern_funcs = {x509_new_cb, x509_free_cb,

                                                    x509_parse_cb, x509_i2d_cb};

IMPLEMENT_EXTERN_ASN1(X509, x509_extern_funcs)

X509 *X509_dup(const X509 *x509) {

  uint8_t *der = nullptr;

  int len = i2d_X509(x509, &der);

  if (len < 0) {

    return nullptr;

  }

  const uint8_t *inp = der;

  X509 *ret = d2i_X509(nullptr, &inp, len);

  OPENSSL_free(der);

  return ret;

}

int X509_up_ref(X509 *x) {

  CRYPTO_refcount_inc(&x->references);

  return 1;

}

int X509_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,

                          CRYPTO_EX_dup *dup_unused,

                          CRYPTO_EX_free *free_func) {

  return CRYPTO_get_ex_new_index_ex(&g_ex_data_class, argl, argp, free_func);

}

int X509_set_ex_data(X509 *r, int idx, void *arg) {

  return (CRYPTO_set_ex_data(&r->ex_data, idx, arg));

}

void *X509_get_ex_data(X509 *r, int idx) {

  return (CRYPTO_get_ex_data(&r->ex_data, idx));

}

// X509_AUX ASN1 routines. X509_AUX is the name given to a certificate with

// extra info tagged on the end. Since these functions set how a certificate

// is trusted they should only be used when the certificate comes from a

// reliable source such as local storage.

X509 *d2i_X509_AUX(X509 **a, const unsigned char **pp, long length) {

  const unsigned char *q = *pp;

  X509 *ret;

  int freeret = 0;

  if (!a || *a == nullptr) {

    freeret = 1;

  }

  ret = d2i_X509(a, &q, length);

  // If certificate unreadable then forget it

  if (!ret) {

    return nullptr;

  }

  // update length

  length -= q - *pp;

  // Parse auxiliary information if there is any.

  if (length > 0 && !d2i_X509_CERT_AUX(&ret->aux, &q, length)) {

    goto err;

  }

  *pp = q;

  return ret;

err:

  if (freeret) {

    X509_free(ret);

    if (a) {

      *a = nullptr;

    }

  }

  return nullptr;

}

// Serialize trusted certificate to *pp or just return the required buffer

// length if pp == NULL.  We ultimately want to avoid modifying *pp in the

// error path, but that depends on similar hygiene in lower-level functions.

// Here we avoid compounding the problem.

static int i2d_x509_aux_internal(const X509 *a, unsigned char **pp) {

  int length, tmplen;

  unsigned char *start = pp != nullptr ? *pp : nullptr;

  assert(pp == nullptr || *pp != nullptr);

  // This might perturb *pp on error, but fixing that belongs in i2d_X509()

  // not here.  It should be that if a == NULL length is zero, but we check

  // both just in case.

  length = i2d_X509(a, pp);

  if (length <= 0 || a == nullptr) {

    return length;

  }

  if (a->aux != nullptr) {

    tmplen = i2d_X509_CERT_AUX(a->aux, pp);

    if (tmplen < 0) {

      if (start != nullptr) {

        *pp = start;

      }

      return tmplen;

    }

    length += tmplen;

  }

  return length;

}

// Serialize trusted certificate to *pp, or just return the required buffer

// length if pp == NULL.

//

// When pp is not NULL, but *pp == NULL, we allocate the buffer, but since

// we're writing two ASN.1 objects back to back, we can't have i2d_X509() do

// the allocation, nor can we allow i2d_X509_CERT_AUX() to increment the

// allocated buffer.

int i2d_X509_AUX(const X509 *a, unsigned char **pp) {

  int length;

  unsigned char *tmp;

  // Buffer provided by caller

  if (pp == nullptr || *pp != nullptr) {

    return i2d_x509_aux_internal(a, pp);

  }

  // Obtain the combined length

  if ((length = i2d_x509_aux_internal(a, nullptr)) <= 0) {

    return length;

  }

  // Allocate requisite combined storage

  *pp = tmp = reinterpret_cast<uint8_t *>(OPENSSL_malloc(length));

  if (tmp == nullptr) {

    return -1;  // Push error onto error stack?

  }

  // Encode, but keep *pp at the originally malloced pointer

  length = i2d_x509_aux_internal(a, &tmp);

  if (length <= 0) {

    OPENSSL_free(*pp);

    *pp = nullptr;

  }

  return length;

}

int i2d_re_X509_tbs(X509 *x509, uint8_t **outp) {

  CRYPTO_BUFFER_free(x509->buf);

  x509->buf = nullptr;

  return i2d_X509_tbs(x509, outp);

}

int i2d_X509_tbs(const X509 *x509, uint8_t **outp) {

  return bssl::I2DFromCBB(/*initial_capacity=*/128, outp, [&](CBB *cbb) -> bool {

    return x509_marshal_tbs_cert(cbb, x509);

  });

}

int X509_set1_signature_algo(X509 *x509, const X509_ALGOR *algo) {

  return X509_ALGOR_copy(&x509->sig_alg, algo) &&

         X509_ALGOR_copy(&x509->tbs_sig_alg, algo);

}

int X509_set1_signature_value(X509 *x509, const uint8_t *sig, size_t sig_len) {

  if (!ASN1_STRING_set(&x509->signature, sig, sig_len)) {

    return 0;

  }

  x509->signature.flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);

  x509->signature.flags |= ASN1_STRING_FLAG_BITS_LEFT;

  return 1;

}

void X509_get0_signature(const ASN1_BIT_STRING **psig, const X509_ALGOR **palg,

                         const X509 *x) {

  if (psig) {

    *psig = &x->signature;

  }

  if (palg) {

    *palg = &x->sig_alg;

  }

}

int X509_get_signature_nid(const X509 *x) {

  return OBJ_obj2nid(x->sig_alg.algorithm);

}