xref: /netbsd/src/crypto/external/bsd/heimdal/dist/lib/asn1/der_get.c

/*        $NetBSD: der_get.c,v 1.3 2023/06/19 21:41:42 christos Exp $ */

/*
 * Copyright (c) 1997 - 2007 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * 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 above 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. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE 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.
 */

#include "der_locl.h"

/*
 * All decoding functions take a pointer `p' to first position in
 * which to read, from the left, `len' which means the maximum number
 * of characters we are able to read, `ret' were the value will be
 * returned and `size' where the number of used bytes is stored.
 * Either 0 or an error code is returned.
 */

int
der_get_unsigned (const unsigned char *p, size_t len,
                      unsigned *ret, size_t *size)
{
    unsigned val = 0;
    size_t oldlen = len;

    if (len == sizeof(val) + 1 && p[0] == 0)
          ;
    else if (len > sizeof(val))
          return ASN1_OVERRUN;

    while (len--)
          val = val * 256 + *p++;
    *ret = val;
    if(size) *size = oldlen;
    return 0;
}

int
der_get_unsigned64 (const unsigned char *p, size_t len,
                   uint64_t *ret, size_t *size)
{
    uint64_t val = 0;
    size_t oldlen = len;

    if (len == sizeof(val) + 1 && p[0] == 0)
       ;
    else if (len > sizeof(val))
          return ASN1_OVERRUN;

    while (len--)
          val = val * 256 + *p++;
    *ret = val;
    if(size) *size = oldlen;
    return 0;
}

int
der_get_integer (const unsigned char *p, size_t len,
                     int *ret, size_t *size)
{
    int val = 0;
    size_t oldlen = len;

    if (len == sizeof(val) + 1 && (p[0] == 0 || p[0] == 0xff))
        ;
    else if (len > sizeof(val))
          return ASN1_OVERRUN;

    /* We assume we're on a twos-complement platform */
    if (len > 0) {
          val = (signed char)*p++;
          while (--len)
              val = val * 256 + *p++;
    }
    *ret = val;
    if(size) *size = oldlen;
    return 0;
}

int
der_get_integer64 (const unsigned char *p, size_t len,
                       int64_t *ret, size_t *size)
{
    int64_t val = 0;
    size_t oldlen = len;

    if (len > sizeof(val))
        return ASN1_OVERRUN;

    /* We assume we're on a twos-complement platform */
    if (len > 0) {
       val = (signed char)*p++;
       while (--len)
           val = val * 256 + *p++;
    }
    *ret = val;
    if(size) *size = oldlen;
    return 0;
}


int
der_get_length (const unsigned char *p, size_t len,
                    size_t *val, size_t *size)
{
    size_t v;

    if (len <= 0)
          return ASN1_OVERRUN;
    --len;
    v = *p++;
    if (v < 128) {
          *val = v;
          if(size) *size = 1;
    } else {
          int e;
          size_t l;
          unsigned tmp;

          if(v == 0x80){
              *val = ASN1_INDEFINITE;
              if(size) *size = 1;
              return 0;
          }
          v &= 0x7F;
          if (len < v)
              return ASN1_OVERRUN;
          e = der_get_unsigned (p, v, &tmp, &l);
          if(e) return e;
          *val = tmp;
          if(size) *size = l + 1;
    }
    return 0;
}

int
der_get_boolean(const unsigned char *p, size_t len, int *data, size_t *size)
{
    if(len < 1)
          return ASN1_OVERRUN;
    if(*p != 0)
          *data = 1;
    else
          *data = 0;
    *size = 1;
    return 0;
}

int
der_get_general_string (const unsigned char *p, size_t len,
                              heim_general_string *str, size_t *size)
{
    const unsigned char *p1;
    char *s;

    p1 = memchr(p, 0, len);
    if (p1 != NULL) {
          /*
           * Allow trailing NULs. We allow this since MIT Kerberos sends
           * an strings in the NEED_PREAUTH case that includes a
           * trailing NUL.
           */
          while ((size_t)(p1 - p) < len && *p1 == '\0')
              p1++;
          if ((size_t)(p1 - p) != len) {
              *str = NULL;
              return ASN1_BAD_CHARACTER;
          }
    }
    if (len == SIZE_MAX) {
          *str = NULL;
          return ASN1_BAD_LENGTH;
    }

    *str = s = malloc (len + 1);
    if (s == NULL)
          return ENOMEM;
    memcpy (s, p, len);
    s[len] = '\0';

    if(size) *size = len;
    return 0;
}

int
der_get_utf8string (const unsigned char *p, size_t len,
                        heim_utf8_string *str, size_t *size)
{
    return der_get_general_string(p, len, str, size);
}

#define gen_data_zero(_data) \
          do { (_data)->length = 0; (_data)->data = NULL; } while(0)

int
der_get_printable_string(const unsigned char *p, size_t len,
                               heim_printable_string *str, size_t *size)
{
    if (len == SIZE_MAX) {
          gen_data_zero(str);
          return ASN1_BAD_LENGTH;
    }
    str->length = len;
    str->data = malloc(len + 1);
    if (str->data == NULL) {
          gen_data_zero(str);
          return ENOMEM;
    }
    memcpy(str->data, p, len);
    ((char *)str->data)[len] = '\0';
    if(size) *size = len;
    return 0;
}

int
der_get_ia5_string(const unsigned char *p, size_t len,
                       heim_ia5_string *str, size_t *size)
{
    return der_get_printable_string(p, len, str, size);
}

int
der_get_bmp_string (const unsigned char *p, size_t len,
                        heim_bmp_string *data, size_t *size)
{
    size_t i;

    if (len & 1) {
          gen_data_zero(data);
          return ASN1_BAD_FORMAT;
    }
    data->length = len / 2;
    if (data->length > UINT_MAX/sizeof(data->data[0])) {
          gen_data_zero(data);
          return ERANGE;
    }
    data->data = malloc(data->length * sizeof(data->data[0]));
    if (data->data == NULL && data->length != 0) {
          gen_data_zero(data);
          return ENOMEM;
    }

    for (i = 0; i < data->length; i++) {
          data->data[i] = (p[0] << 8) | p[1];
          p += 2;
          /* check for NUL in the middle of the string */
          if (data->data[i] == 0 && i != (data->length - 1)) {
              free(data->data);
              gen_data_zero(data);
              return ASN1_BAD_CHARACTER;
          }
    }
    if (size) *size = len;

    return 0;
}

int
der_get_universal_string (const unsigned char *p, size_t len,
                                heim_universal_string *data, size_t *size)
{
    size_t i;

    if (len & 3) {
          gen_data_zero(data);
          return ASN1_BAD_FORMAT;
    }
    data->length = len / 4;
    if (data->length > UINT_MAX/sizeof(data->data[0])) {
          gen_data_zero(data);
          return ERANGE;
    }
    data->data = malloc(data->length * sizeof(data->data[0]));
    if (data->data == NULL && data->length != 0) {
          gen_data_zero(data);
          return ENOMEM;
    }

    for (i = 0; i < data->length; i++) {
          data->data[i] = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
          p += 4;
          /* check for NUL in the middle of the string */
          if (data->data[i] == 0 && i != (data->length - 1)) {
              free(data->data);
              gen_data_zero(data);
              return ASN1_BAD_CHARACTER;
          }
    }
    if (size) *size = len;
    return 0;
}

int
der_get_visible_string (const unsigned char *p, size_t len,
                              heim_visible_string *str, size_t *size)
{
    return der_get_general_string(p, len, str, size);
}

int
der_get_octet_string (const unsigned char *p, size_t len,
                          heim_octet_string *data, size_t *size)
{
    data->length = len;
    data->data = malloc(len);
    if (data->data == NULL && data->length != 0)
          return ENOMEM;
    memcpy (data->data, p, len);
    if(size) *size = len;
    return 0;
}

int
der_get_octet_string_ber (const unsigned char *p, size_t len,
                                heim_octet_string *data, size_t *size)
{
    int e;
    Der_type type;
    Der_class cls;
    unsigned int tag, depth = 0;
    size_t l, datalen, oldlen = len;

    data->length = 0;
    data->data = NULL;

    while (len) {
          e = der_get_tag (p, len, &cls, &type, &tag, &l);
          if (e) goto out;
          if (cls != ASN1_C_UNIV) {
              e = ASN1_BAD_ID;
              goto out;
          }
          if (type == PRIM && tag == UT_EndOfContent) {
              if (depth == 0)
                    break;
              depth--;
          }
          if (tag != UT_OctetString) {
              e = ASN1_BAD_ID;
              goto out;
          }

          p += l;
          len -= l;
          e = der_get_length (p, len, &datalen, &l);
          if (e) goto out;
          p += l;
          len -= l;

          if (datalen > len)
              return ASN1_OVERRUN;

          if (type == PRIM) {
              void *ptr;

              ptr = realloc(data->data, data->length + datalen);
              if (ptr == NULL) {
                    e = ENOMEM;
                    goto out;
              }
              data->data = ptr;
              memcpy(((unsigned char *)data->data) + data->length, p, datalen);
              data->length += datalen;
          } else
              depth++;

          p += datalen;
          len -= datalen;
    }
    if (depth != 0)
          return ASN1_INDEF_OVERRUN;
    if(size) *size = oldlen - len;
    return 0;
 out:
    free(data->data);
    data->data = NULL;
    data->length = 0;
    return e;
}


int
der_get_heim_integer (const unsigned char *p, size_t len,
                          heim_integer *data, size_t *size)
{
    data->length = 0;
    data->negative = 0;
    data->data = NULL;

    if (len == 0) {
          if (size)
              *size = 0;
          return 0;
    }
    if (p[0] & 0x80) {
          unsigned char *q;
          int carry = 1;


        /*
         * A negative number.  It's going to be a twos complement byte array.
         * We're going to leave the positive value in `data->data', but set the
         * `data->negative' flag.  That means we need to negate the
         * twos-complement integer received.
         */
          data->negative = 1;
          data->length = len;

          if (p[0] == 0xff) {
            if (data->length == 1) {
                /* One byte of all ones == -1 */
                q = data->data = malloc(1);
                *q = 1;
                data->length = 1;
                if (size)
                    *size = 1;
                return 0;
            }

              p++;
              data->length--;

            /*
             * We could check if the next byte's high bit is set, which would
             * be an error ("illegal padding" in OpenSSL).  However, this would
             * mean failing to accept certificates made by certain CAs that
             * would read 8 bytes of RNG into a buffer, slap on length 8, then
             * slap on the tag [UNIVERSAL INTEGER], and make that the
             * serialNumber field's encoding, which then fails to parse in
             * around 1 in 256 certificates.
             *
             * So let's not.
             *
             * if (p[0] & 0x80)
             *     return ASN1_PARSE_ERROR; // or a new error code
             */
          }
          data->data = malloc(data->length);
          if (data->data == NULL) {
              data->length = 0;
              if (size)
                    *size = 0;
              return ENOMEM;
          }

        /*
         * Note that if `data->length' were zero, this would be UB because we
         * underflow if data->length is zero even though we wouldn't actually
         * dereference the byte before data->data.  Thus we check above for
         * that.
         */
          q = &((unsigned char*)data->data)[data->length - 1];
          p += data->length - 1;
          while (q >= (unsigned char*)data->data) {
            /* *p XOR 0xff -> ~*p; we're dealing with twos complement */
              *q = *p ^ 0xff;
              if (carry)
                    carry = !++*q;
              p--;
              q--;
          }
    } else {
          data->negative = 0;
          data->length = len;

          if (p[0] == 0) {
              p++;
              data->length--;
          }
          data->data = malloc(data->length);
          if (data->data == NULL && data->length != 0) {
              data->length = 0;
              if (size)
                    *size = 0;
              return ENOMEM;
          }
          memcpy(data->data, p, data->length);
    }
    if (size)
          *size = len;
    return 0;
}

static int
generalizedtime2time (const char *s, time_t *t)
{
    struct tm tm;

    memset(&tm, 0, sizeof(tm));
    if (sscanf (s, "%04d%02d%02d%02d%02d%02dZ",
                    &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
                    &tm.tm_min, &tm.tm_sec) != 6) {
          if (sscanf (s, "%02d%02d%02d%02d%02d%02dZ",
                        &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
                        &tm.tm_min, &tm.tm_sec) != 6)
              return ASN1_BAD_TIMEFORMAT;
          if (tm.tm_year < 50)
              tm.tm_year += 2000;
          else
              tm.tm_year += 1900;
    }
    tm.tm_year -= 1900;
    tm.tm_mon -= 1;
    *t = _der_timegm (&tm);
    return 0;
}

static int
der_get_time (const unsigned char *p, size_t len,
                time_t *data, size_t *size)
{
    char *times;
    int e;

    if (len == SIZE_MAX || len == 0)
          return ASN1_BAD_LENGTH;

    times = malloc(len + 1);
    if (times == NULL)
          return ENOMEM;
    memcpy(times, p, len);
    times[len] = '\0';
    e = generalizedtime2time(times, data);
    free (times);
    if(size) *size = len;
    return e;
}

int
der_get_generalized_time (const unsigned char *p, size_t len,
                                time_t *data, size_t *size)
{
    return der_get_time(p, len, data, size);
}

int
der_get_utctime (const unsigned char *p, size_t len,
                                time_t *data, size_t *size)
{
    return der_get_time(p, len, data, size);
}

int
der_get_oid (const unsigned char *p, size_t len,
               heim_oid *data, size_t *size)
{
    size_t n;
    size_t oldlen = len;

    if (len < 1)
          return ASN1_OVERRUN;

    if (len == SIZE_MAX)
          return ASN1_BAD_LENGTH;

    if (len + 1 > UINT_MAX/sizeof(data->components[0]))
          return ERANGE;

    data->components = malloc((len + 1) * sizeof(data->components[0]));
    if (data->components == NULL)
          return ENOMEM;
    data->components[0] = (*p) / 40;
    data->components[1] = (*p) % 40;
    --len;
    ++p;
    for (n = 2; len > 0; ++n) {
          unsigned u = 0, u1;

          do {
              --len;
              u1 = u * 128 + (*p++ % 128);
              /* check that we don't overflow the element */
              if (u1 < u) {
                    der_free_oid(data);
                    return ASN1_OVERRUN;
              }
              u = u1;
          } while (len > 0 && p[-1] & 0x80);
          data->components[n] = u;
    }
    if (n > 2 && p[-1] & 0x80) {
          der_free_oid (data);
          return ASN1_OVERRUN;
    }
    data->length = n;
    if (size)
          *size = oldlen;
    return 0;
}

int
der_get_tag (const unsigned char *p, size_t len,
               Der_class *cls, Der_type *type,
               unsigned int *tag, size_t *size)
{
    size_t ret = 0;
    if (len < 1)
          return ASN1_OVERRUN;
    *cls = (Der_class)(((*p) >> 6) & 0x03);
    *type = (Der_type)(((*p) >> 5) & 0x01);
    *tag = (*p) & 0x1f;
    p++; len--; ret++;
    if(*tag == 0x1f) {
          unsigned int continuation;
          unsigned int tag1;
          *tag = 0;
          do {
              if(len < 1)
                    return ASN1_OVERRUN;
              continuation = *p & 128;
              tag1 = *tag * 128 + (*p % 128);
              /* check that we don't overflow the tag */
              if (tag1 < *tag)
                    return ASN1_OVERFLOW;
              *tag = tag1;
              p++; len--; ret++;
          } while(continuation);
    }
    if(size) *size = ret;
    return 0;
}

int
der_match_tag (const unsigned char *p, size_t len,
                 Der_class cls, Der_type type,
                 unsigned int tag, size_t *size)
{
    Der_type thistype;
    int e;

    e = der_match_tag2(p, len, cls, &thistype, tag, size);
    if (e) return e;
    if (thistype != type) return ASN1_BAD_ID;
    return 0;
}

int
der_match_tag2 (const unsigned char *p, size_t len,
                    Der_class cls, Der_type *type,
                    unsigned int tag, size_t *size)
{
    size_t l;
    Der_class thisclass;
    unsigned int thistag;
    int e;

    e = der_get_tag (p, len, &thisclass, type, &thistag, &l);
    if (e) return e;
    if (cls != thisclass)
          return ASN1_BAD_ID;
    if(tag > thistag)
          return ASN1_MISPLACED_FIELD;
    if(tag < thistag)
          return ASN1_MISSING_FIELD;
    if(size) *size = l;
    return 0;
}

int
der_match_tag_and_length (const unsigned char *p, size_t len,
                                Der_class cls, Der_type *type, unsigned int tag,
                                size_t *length_ret, size_t *size)
{
    size_t l, ret = 0;
    int e;

    e = der_match_tag2 (p, len, cls, type, tag, &l);
    if (e) return e;
    p += l;
    len -= l;
    ret += l;
    e = der_get_length (p, len, length_ret, &l);
    if (e) return e;
    if(size) *size = ret + l;
    return 0;
}



/*
 * Old versions of DCE was based on a very early beta of the MIT code,
 * which used MAVROS for ASN.1 encoding. MAVROS had the interesting
 * feature that it encoded data in the forward direction, which has
 * it's problems, since you have no idea how long the data will be
 * until after you're done. MAVROS solved this by reserving one byte
 * for length, and later, if the actual length was longer, it reverted
 * to indefinite, BER style, lengths. The version of MAVROS used by
 * the DCE people could apparently generate correct X.509 DER encodings, and
 * did this by making space for the length after encoding, but
 * unfortunately this feature wasn't used with Kerberos.
 */

int
_heim_fix_dce(size_t reallen, size_t *len)
{
    if(reallen == ASN1_INDEFINITE)
          return 1;
    if(*len < reallen)
          return -1;
    *len = reallen;
    return 0;
}

int
der_get_bit_string (const unsigned char *p, size_t len,
                        heim_bit_string *data, size_t *size)
{
    if (len < 1)
          return ASN1_OVERRUN;
    if (p[0] > 7)
          return ASN1_BAD_FORMAT;
    if (len - 1 == 0 && p[0] != 0)
          return ASN1_BAD_FORMAT;
    /* check if any of the three upper bits are set
     * any of them will cause a interger overrun */
    if ((len - 1) >> (sizeof(len) * 8 - 3))
          return ASN1_OVERRUN;
    /*
     * If there is data to copy, do that now.
     */
    if (len - 1 > 0) {
          data->length = (len - 1) * 8;
          data->data = malloc(len - 1);
          if (data->data == NULL)
              return ENOMEM;
          memcpy (data->data, p + 1, len - 1);
          data->length -= p[0];
    } else {
          data->data = NULL;
          data->length = 0;
    }
    if(size) *size = len;
    return 0;
}