crypto/asn1/internal.h

// Copyright 2005-2016 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.

#ifndef OPENSSL_HEADER_CRYPTO_ASN1_INTERNAL_H
#define OPENSSL_HEADER_CRYPTO_ASN1_INTERNAL_H

#include <time.h>

#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <openssl/span.h>

#include "../internal.h"


BSSL_NAMESPACE_BEGIN

// Wrapper functions for time functions.

// OPENSSL_gmtime converts a time_t value in `time` which must be in the range
// of year 0000 to 9999 to a broken out time value in `tm`. On success `tm` is
// returned. On failure NULL is returned.
OPENSSL_EXPORT struct tm *OPENSSL_gmtime(const time_t *time, struct tm *result);

// OPENSSL_gmtime_adj returns one on success, and updates `tm` by adding
// `offset_day` days and `offset_sec` seconds. It returns zero on failure. `tm`
// must be in the range of year 0000 to 9999 both before and after the update or
// a failure will be returned.
OPENSSL_EXPORT int OPENSSL_gmtime_adj(struct tm *tm, int offset_day,
                                      int64_t offset_sec);

// OPENSSL_gmtime_diff calculates the difference between `from` and `to`. It
// returns one, and outputs the difference as a number of days and seconds in
// `*out_days` and `*out_secs` on success. It returns zero on failure.  Both
// `from` and `to` must be in the range of year 0000 to 9999 or a failure will
// be returned.
OPENSSL_EXPORT int OPENSSL_gmtime_diff(int *out_days, int *out_secs,
                                       const struct tm *from,
                                       const struct tm *to);


// Object identifiers.

// These are used internally in the ASN1_OBJECT to keep track of
// whether the names and data need to be free()ed
#define ASN1_OBJECT_FLAG_DYNAMIC 0x01          // internal use
#define ASN1_OBJECT_FLAG_DYNAMIC_STRINGS 0x04  // internal use
#define ASN1_OBJECT_FLAG_DYNAMIC_DATA 0x08     // internal use

BSSL_NAMESPACE_END

// An asn1_object_st (aka `ASN1_OBJECT`) represents an ASN.1 OBJECT IDENTIFIER.
// Note: Mutating an `ASN1_OBJECT` is only permitted when initializing it. The
// library maintains a table of static `ASN1_OBJECT`s, which may be referenced
// by non-const `ASN1_OBJECT` pointers. Code which receives an `ASN1_OBJECT`
// pointer externally must assume it is immutable, even if the pointer is not
// const.
struct asn1_object_st {
  const char *sn, *ln;
  int nid;
  int length;
  const unsigned char *data;  // data remains const after init
  int flags;                  // Should we free this one
};

BSSL_NAMESPACE_BEGIN

ASN1_OBJECT *ASN1_OBJECT_new();

// asn1_parse_object parses a DER-encoded ASN.1 OBJECT IDENTIFIER from `cbs` and
// write the result to `out`. If `tag` is non-zero, the value is implicitly
// tagged with `tag`. On success, it returns a newly-allocated `ASN1_OBJECT`
// with the result and advances `cbs` past the parsed element.
//
// TODO(crbug.com/boringssl/414361735): This should return a bssl::UniquePtr,
// but cannot until it is made C++ linkage.
ASN1_OBJECT *asn1_parse_object(CBS *cbs, CBS_ASN1_TAG tag);

// asn1_marshal_object marshals `in` as a DER-encoded, ASN.1 OBJECT IDENTIFIER
// and writes the result to `out`. It returns one on success and zero on error.
// If `tag` is non-zero, the tag is replaced with `tag`.
int asn1_marshal_object(CBB *out, const ASN1_OBJECT *in, CBS_ASN1_TAG tag);


// Strings.

// asn1_is_printable returns one if `value` is a valid Unicode codepoint for an
// ASN.1 PrintableString, and zero otherwise.
int asn1_is_printable(uint32_t value);

// asn1_string_init initializes `str`, which may be uninitialized, with type
// `type`.
void asn1_string_init(ASN1_STRING *str, int type);

// asn1_string_cleanup releases memory associated with `str`'s value, without
// freeing `str` itself.
void asn1_string_cleanup(ASN1_STRING *str);

// A ScopedASN1String is a stack-allocatable `ASN1_STRING` with managed
// lifetime.
// TODO(crbug.com/443769299): Once `ASN1_STRING` is no longer public, this can
// instead use `DECLARE_OPAQUE_STRUCT`.
class ScopedASN1String {
 public:
  explicit ScopedASN1String(int type) { asn1_string_init(&str_, type); }
  ScopedASN1String(const ScopedASN1String &) = delete;
  ScopedASN1String &operator=(const ScopedASN1String &) = delete;
  ~ScopedASN1String() { asn1_string_cleanup(&str_); }

  ASN1_STRING *get() { return &str_; }
  const ASN1_STRING *get() const { return &str_; }
  ASN1_STRING *operator->() { return &str_; }
  const ASN1_STRING *operator->() const { return &str_; }

 private:
  ASN1_STRING str_;
};

// asn1_parse_string_unchecked parses a DER-encoded string of type `str_type`,
// tagged with `tag`. It does not check the contents.
int asn1_parse_string_unchecked(CBS *cbs, ASN1_STRING *out, int str_type,
                                CBS_ASN1_TAG tag);

// The following functions parse a DER-encoded ASN.1 value of the specified
// type from `cbs` and write the result to `*out`. If `tag` is non-zero, the
// value is implicitly tagged with `tag`. On success, they return one and
// advance `cbs` past the parsed element. On entry, `*out` must contain an
// `ASN1_STRING` in some valid state.
int asn1_parse_bit_string(CBS *cbs, ASN1_BIT_STRING *out, CBS_ASN1_TAG tag);
int asn1_parse_integer(CBS *cbs, ASN1_INTEGER *out, CBS_ASN1_TAG tag);
int asn1_parse_enumerated(CBS *cbs, ASN1_ENUMERATED *out, CBS_ASN1_TAG tag);
int asn1_parse_octet_string(CBS *cbs, ASN1_STRING *out, CBS_ASN1_TAG tag);
int asn1_parse_t61_string(CBS *cbs, ASN1_STRING *out, CBS_ASN1_TAG tag);
int asn1_parse_bmp_string(CBS *cbs, ASN1_BMPSTRING *out, CBS_ASN1_TAG tag);
int asn1_parse_universal_string(CBS *cbs, ASN1_UNIVERSALSTRING *out,
                                CBS_ASN1_TAG tag);
int asn1_parse_utf8_string(CBS *cbs, ASN1_UNIVERSALSTRING *out,
                           CBS_ASN1_TAG tag);
int asn1_parse_generalized_time(CBS *cbs, ASN1_GENERALIZEDTIME *out,
                                CBS_ASN1_TAG tag);
int asn1_parse_utc_time(CBS *cbs, ASN1_UTCTIME *out, CBS_ASN1_TAG tag,
                        int allow_timezone_offset);

// asn1_parse_bit_string_with_bad_length behaves like `asn1_parse_bit_string`
// but tolerates BER non-minimal, definite lengths.
int asn1_parse_bit_string_with_bad_length(CBS *cbs, ASN1_BIT_STRING *out);

// asn1_marshal_bit_string marshals `in` as a DER-encoded, ASN.1 BIT STRING and
// writes the result to `out`. It returns one on success and zero on error. If
// `tag` is non-zero, the tag is replaced with `tag`.
int asn1_marshal_bit_string(CBB *out, const ASN1_BIT_STRING *in,
                            CBS_ASN1_TAG tag);

// asn1_marshal_integer marshals `in` as a DER-encoded, ASN.1 INTEGER and writes
// the result to `out`. It returns one on success and zero on error. If `tag` is
// non-zero, the tag is replaced with `tag`. This can also be used to marshal an
// ASN.1 ENUMERATED value by overriding the tag.
int asn1_marshal_integer(CBB *out, const ASN1_INTEGER *in, CBS_ASN1_TAG tag);

// asn1_marshal_octet_string marshals `in` as a DER-encoded, ASN.1 OCTET STRING
// and writes the result to `out`. It returns one on success and zero on error.
// If `tag` is non-zero, the tag is replaced with `tag`.
//
// This function may be used to marshal other string-based universal types whose
// encoding is that of an implicitly-tagged OCTET STRING, e.g. UTF8String.
int asn1_marshal_octet_string(CBB *out, const ASN1_STRING *in,
                              CBS_ASN1_TAG tag);

OPENSSL_EXPORT int asn1_utctime_to_tm(struct tm *tm, const ASN1_UTCTIME *d,
                                      int allow_timezone_offset);
OPENSSL_EXPORT int asn1_generalizedtime_to_tm(struct tm *tm,
                                              const ASN1_GENERALIZEDTIME *d);

int asn1_parse_time(CBS *cbs, ASN1_TIME *out, int allow_utc_timezone_offset);
int asn1_marshal_time(CBB *cbb, const ASN1_TIME *in);


// The ASN.1 ANY type.

// asn1_type_value_as_pointer returns `a`'s value in pointer form. This is
// usually the value object but, for BOOLEAN values, is 0 or 0xff cast to
// a pointer.
const void *asn1_type_value_as_pointer(const ASN1_TYPE *a);

// asn1_type_set0_string sets `a`'s value to the object represented by `str` and
// takes ownership of `str`.
void asn1_type_set0_string(ASN1_TYPE *a, ASN1_STRING *str);

// asn1_parse_any parses a DER-encoded ASN.1 value of any type from `cbs` and
// writes the result to `*out`. On success, it advances `cbs` past the parsed
// element and returns one. On entry, `*out` must contain an `ASN1_TYPE` in some
// valid state.
int asn1_parse_any(CBS *cbs, ASN1_TYPE *out);

// asn1_parse_any_as_string behaves like `asn1_parse_any` but represents the
// value as an `ASN1_STRING`. Types which are not represented with
// `ASN1_STRING`, such as `ASN1_OBJECT`, are represented with type
// `V_ASN1_OTHER`.
int asn1_parse_any_as_string(CBS *cbs, ASN1_STRING *out);

// asn1_marshal_any marshals `in` as a DER-encoded ASN.1 value and writes the
// result to `out`. It returns one on success and zero on error.
int asn1_marshal_any(CBB *out, const ASN1_TYPE *in);

// asn1_marshal_any_string marshals `in` as a DER-encoded ASN.1 value and writes
// the result to `out`. It returns one on success and zero on error.
int asn1_marshal_any_string(CBB *out, const ASN1_STRING *in);


// Support structures for the template-based encoder.

// ASN1_ENCODING is used to save the received encoding of an ASN.1 type. This
// avoids problems with invalid encodings that break signatures.
typedef struct ASN1_ENCODING_st {
  // enc is the saved DER encoding. Its ownership is determined by `buf`.
  uint8_t *enc;
  // len is the length of `enc`. If zero, there is no saved encoding.
  size_t len;
} ASN1_ENCODING;

int ASN1_item_ex_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
void ASN1_item_ex_free(ASN1_VALUE **pval, const ASN1_ITEM *it);

void ASN1_template_free(ASN1_VALUE **pval, const ASN1_TEMPLATE *tt);

void ASN1_primitive_free(ASN1_VALUE **pval, const ASN1_ITEM *it);

// asn1_load_ptr returns `*pval`, but without asserting `*pval`'s underlying
// type for strict aliasing. This helper must be used when the field's
// underlying type is not known statically. It must not be used for
// `ASN1_BOOLEAN` fields, which are not a pointers.
inline ASN1_VALUE *asn1_load_ptr(ASN1_VALUE **pval) {
  ASN1_VALUE *ret;
  OPENSSL_memcpy(&ret, pval, sizeof(ASN1_VALUE *));
  return ret;
}

// asn1_load_ptr_as behaves like `asn1_load_ptr`, but casts the result to `T*`.
template <typename T>
inline T *asn1_load_ptr_as(ASN1_VALUE **pval) {
  return reinterpret_cast<T *>(asn1_load_ptr(pval));
}

// asn1_store_ptr sets `*pval` to `v`, but without asserting `*pval`'s
// underlying type for strict aliasing. This helper must be used when the
// field's underlying type is not known statically. It must not be used for
// `ASN1_BOOLEAN` fields, which are not a pointers.
inline void asn1_store_ptr(ASN1_VALUE **pval, const void *v) {
  OPENSSL_memcpy(pval, &v, sizeof(v));
}

// asn1_get_choice_selector returns the CHOICE selector value for `*pval`, which
// must of type `it`.
int asn1_get_choice_selector(ASN1_VALUE **pval, const ASN1_ITEM *it);

int asn1_set_choice_selector(ASN1_VALUE **pval, int value, const ASN1_ITEM *it);

// asn1_get_field_ptr returns a pointer to the field in `*pval` corresponding to
// `tt`.
ASN1_VALUE **asn1_get_field_ptr(ASN1_VALUE **pval, const ASN1_TEMPLATE *tt);

// asn1_do_adb returns the `ASN1_TEMPLATE` for the ANY DEFINED BY field `tt`,
// based on the selector INTEGER or OID in `*pval`. If `tt` is not an ADB field,
// it returns `tt`. If the selector does not match any value, it returns NULL.
// If `nullerr` is non-zero, it will additionally push an error to the error
// queue when there is no match.
const ASN1_TEMPLATE *asn1_do_adb(ASN1_VALUE **pval, const ASN1_TEMPLATE *tt,
                                 int nullerr);

void asn1_refcount_set_one(ASN1_VALUE **pval, const ASN1_ITEM *it);
int asn1_refcount_dec_and_test_zero(ASN1_VALUE **pval, const ASN1_ITEM *it);

void asn1_enc_init(ASN1_VALUE **pval, const ASN1_ITEM *it);
void asn1_enc_free(ASN1_VALUE **pval, const ASN1_ITEM *it);

// asn1_enc_restore, if `*pval` has a saved encoding, sets `*out` to it, and
// returns one. If it has no saved encoding, it returns zero.
int asn1_enc_restore(Span<const uint8_t> *out, ASN1_VALUE **pval,
                     const ASN1_ITEM *it);

// asn1_enc_save saves `inlen` bytes from `in` as `*pval`'s saved encoding. It
// returns one on success and zero on error. If `buf` is non-NULL, `in` must
// point into `buf`.
int asn1_enc_save(ASN1_VALUE **pval, const uint8_t *in, size_t inlen,
                  const ASN1_ITEM *it);

// asn1_encoding_clear clears the cached encoding in `enc`.
void asn1_encoding_clear(ASN1_ENCODING *enc);

// asn1_tag_to_cbs converts a tag from this library's representation (the
// `V_ASN1_*` constants) to that of `CBS` and `CBB`. It returns the tag on
// success and zero if the input could not be represented. (Zero would be
// [UNIVERSAL 0], which is a reserved tag value.)
//
// The resulting tag will not have the constructed bit set. The caller must OR
// the result with `CBS_ASN1_CONSTRUCTED` if necessary, before passing to
// `CBS` and `CBB` functions.
CBS_ASN1_TAG asn1_tag_to_cbs(int aclass, int tag);

typedef struct {
  int nid;
  long minsize;
  long maxsize;
  unsigned long mask;
  unsigned long flags;
} ASN1_STRING_TABLE;

// asn1_get_string_table_for_testing sets `*out_ptr` and `*out_len` to the table
// of built-in `ASN1_STRING_TABLE` values. It is exported for testing.
OPENSSL_EXPORT void asn1_get_string_table_for_testing(
    const ASN1_STRING_TABLE **out_ptr, size_t *out_len);

typedef ASN1_VALUE *ASN1_new_func();
typedef void ASN1_free_func(ASN1_VALUE *a);
typedef ASN1_VALUE *ASN1_d2i_func(ASN1_VALUE **a, const unsigned char **in,
                                  long length);
typedef int ASN1_i2d_func(ASN1_VALUE *a, unsigned char **in);

// An ASN1_ex_parse function should parse a value from `cbs` and set `*pval` to
// the result. It should return one on success and zero on failure. If `opt` is
// non-zero, the field may be optional. If an optional element is missing, the
// function should return one and consume zero bytes from `cbs`.
//
// If `opt` is non-zero, the function can assume that `*pval` is nullptr on
// entry. Otherwise, `*pval` may either be nullptr, or the result of
// `ASN1_ex_new_func`. The function may either write into the existing object,
// if any, or unconditionally make a new one. (The existing object comes from
// tasn_new.cc recursively filling in objects before parsing into them.)
typedef int ASN1_ex_parse(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it,
                          int opt);

// An ASN1_ex_marshal function should marshal `*pval`, a value of type `it`, to
// `cbb` and return one on success or zero on error.
typedef int ASN1_ex_marshal(CBB *cbb, ASN1_VALUE **pval, const ASN1_ITEM *it);

typedef int ASN1_ex_new_func(ASN1_VALUE **pval, const ASN1_ITEM *it);
typedef void ASN1_ex_free_func(ASN1_VALUE **pval, const ASN1_ITEM *it);

typedef struct ASN1_EXTERN_FUNCS_st {
  ASN1_ex_new_func *asn1_ex_new;
  ASN1_ex_free_func *asn1_ex_free;
  ASN1_ex_parse *asn1_ex_parse;
  ASN1_ex_marshal *asn1_ex_marshal;
} ASN1_EXTERN_FUNCS;

// IMPLEMENT_EXTERN_ASN1_PARSE_NEW implements an `ASN1_ITEM` for a type whose
// parse function returns a new object.
#define IMPLEMENT_EXTERN_ASN1_PARSE_NEW(name, new_func, free_func, tag,        \
                                        parse_func, marshal_func)              \
  static int name##_new_cb(ASN1_VALUE **pval, const ASN1_ITEM *it) {           \
    name *obj = new_func();                                                    \
    if (obj == nullptr) {                                                      \
      return 0;                                                                \
    }                                                                          \
    asn1_store_ptr(pval, obj);                                                 \
    return 1;                                                                  \
  }                                                                            \
                                                                               \
  static void name##_free_cb(ASN1_VALUE **pval, const ASN1_ITEM *it) {         \
    free_func(asn1_load_ptr_as<name>(pval));                                   \
    asn1_store_ptr(pval, nullptr);                                             \
  }                                                                            \
                                                                               \
  static int name##_parse_cb(ASN1_VALUE **pval, CBS *cbs, const ASN1_ITEM *it, \
                             int opt) {                                        \
    if (opt && !CBS_peek_asn1_tag(cbs, (tag))) {                               \
      return 1;                                                                \
    }                                                                          \
                                                                               \
    bssl::UniquePtr<name> ret = parse_func(cbs);                               \
    if (ret == nullptr) {                                                      \
      return 0;                                                                \
    }                                                                          \
    name##_free_cb(pval, it);                                                  \
    asn1_store_ptr(pval, ret.release());                                       \
    return 1;                                                                  \
  }                                                                            \
                                                                               \
  static int name##_marshal_cb(CBB *cbb, ASN1_VALUE **pval,                    \
                               const ASN1_ITEM *it) {                          \
    return marshal_func(cbb, asn1_load_ptr_as<name>(pval));                    \
  }                                                                            \
                                                                               \
  static const ASN1_EXTERN_FUNCS name##_extern_funcs = {                       \
      name##_new_cb, name##_free_cb, name##_parse_cb, name##_marshal_cb};      \
                                                                               \
  IMPLEMENT_EXTERN_ASN1(name, name##_extern_funcs)

// IMPLEMENT_EXTERN_ASN1_PARSE_INTO implements an `ASN1_ITEM` for a type whose
// parse function writes into an existing object.
#define IMPLEMENT_EXTERN_ASN1_PARSE_INTO(name, new_func, free_func, tag, \
                                         parse_func, marshal_func)       \
                                                                         \
  static bssl::UniquePtr<name> name##_parse_new(CBS *cbs) {              \
    bssl::UniquePtr<name> ret(new_func());                               \
    if (ret == nullptr || !parse_func(cbs, ret.get())) {                 \
      return 0;                                                          \
    }                                                                    \
    return ret;                                                          \
  }                                                                      \
                                                                         \
  IMPLEMENT_EXTERN_ASN1_PARSE_NEW(name, new_func, free_func, tag,        \
                                  name##_parse_new, marshal_func)

// ASN1_TIME is an `ASN1_ITEM` whose ASN.1 type is X.509 Time (RFC 5280) and C
// type is `ASN1_TIME*`.
DECLARE_ASN1_ITEM(ASN1_TIME)

// DIRECTORYSTRING is an `ASN1_ITEM` whose ASN.1 type is X.509 DirectoryString
// (RFC 5280) and C type is `ASN1_STRING*`.
DECLARE_ASN1_ITEM(DIRECTORYSTRING)

// DISPLAYTEXT is an `ASN1_ITEM` whose ASN.1 type is X.509 DisplayText (RFC
// 5280) and C type is `ASN1_STRING*`.
DECLARE_ASN1_ITEM(DISPLAYTEXT)

BSSL_NAMESPACE_END

#endif  // OPENSSL_HEADER_CRYPTO_ASN1_INTERNAL_H