cosmopolitan/third_party/mbedtls/asn1parse.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:4;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright The Mbed TLS Contributors                                          │
│                                                                              │
│ 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                                      │
│                                                                              │
│     http://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 "libc/str/str.h"
#include "third_party/mbedtls/asn1.h"
#include "third_party/mbedtls/bignum.h"
#include "third_party/mbedtls/common.h"
#include "third_party/mbedtls/error.h"
#include "third_party/mbedtls/platform.h"

asm(".ident\t\"\\n\\n\
Mbed TLS (Apache 2.0)\\n\
Copyright ARM Limited\\n\
Copyright Mbed TLS Contributors\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */

#if defined(MBEDTLS_ASN1_PARSE_C)

/*
 * ASN.1 DER decoding routines
 */
int mbedtls_asn1_get_len_impl( unsigned char **p,
                               const unsigned char *end,
                               size_t *len )
{
    if( ( end - *p ) < 1 )
        return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
    if( ( **p & 0x80 ) == 0 )
        *len = *(*p)++;
    else
    {
        switch( **p & 0x7F )
        {
        case 1:
            if( ( end - *p ) < 2 )
                return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
            *len = (*p)[1];
            (*p) += 2;
            break;
        case 2:
            if( ( end - *p ) < 3 )
                return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
            *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
            (*p) += 3;
            break;
        case 3:
            if( ( end - *p ) < 4 )
                return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
            *len = ( (size_t)(*p)[1] << 16 ) |
                   ( (size_t)(*p)[2] << 8  ) | (*p)[3];
            (*p) += 4;
            break;
        case 4:
            if( ( end - *p ) < 5 )
                return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
            *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
                   ( (size_t)(*p)[3] << 8  ) |           (*p)[4];
            (*p) += 5;
            break;
        default:
            return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
        }
    }
    if( *len > (size_t) ( end - *p ) )
        return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
    return( 0 );
}

int mbedtls_asn1_get_bool( unsigned char **p,
                           const unsigned char *end,
                           int *val )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    size_t len;
    if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
        return( ret );
    if( len != 1 )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    *val = ( **p != 0 ) ? 1 : 0;
    (*p)++;
    return( 0 );
}

static int asn1_get_tagged_int( unsigned char **p,
                                const unsigned char *end,
                                int tag, int *val )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    size_t len;
    if( ( ret = mbedtls_asn1_get_tag( p, end, &len, tag ) ) != 0 )
        return( ret );
    /*
     * len==0 is malformed (0 must be represented as 020100 for INTEGER,
     * or 0A0100 for ENUMERATED tags
     */
    if( len == 0 )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    /* This is a cryptography library. Reject negative integers. */
    if( ( **p & 0x80 ) != 0 )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    /* Skip leading zeros. */
    while( len > 0 && **p == 0 )
    {
        ++( *p );
        --len;
    }
    /* Reject integers that don't fit in an int. This code assumes that
     * the int type has no padding bit. */
    if( len > sizeof( int ) )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    if( len == sizeof( int ) && ( **p & 0x80 ) != 0 )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    *val = 0;
    while( len-- > 0 )
    {
        *val = ( *val << 8 ) | **p;
        (*p)++;
    }
    return( 0 );
}

int mbedtls_asn1_get_int( unsigned char **p,
                          const unsigned char *end,
                          int *val )
{
    return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_INTEGER, val) );
}

int mbedtls_asn1_get_enum( unsigned char **p,
                           const unsigned char *end,
                           int *val )
{
    return( asn1_get_tagged_int( p, end, MBEDTLS_ASN1_ENUMERATED, val) );
}

int mbedtls_asn1_get_mpi( unsigned char **p,
                          const unsigned char *end,
                          mbedtls_mpi *X )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    size_t len;
    if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
        return( ret );
    ret = mbedtls_mpi_read_binary( X, *p, len );
    *p += len;
    return( ret );
}

int mbedtls_asn1_get_bitstring( unsigned char **p,
                                const unsigned char *end,
                                mbedtls_asn1_bitstring *bs)
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    /* Certificate type is a single byte bitstring */
    if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
        return( ret );
    /* Check length, subtract one for actual bit string length */
    if( bs->len < 1 )
        return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
    bs->len -= 1;
    /* Get number of unused bits, ensure unused bits <= 7 */
    bs->unused_bits = **p;
    if( bs->unused_bits > 7 )
        return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
    (*p)++;
    /* Get actual bitstring */
    bs->p = *p;
    *p += bs->len;
    if( *p != end )
        return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
    return( 0 );
}

/*
 * Traverse an ASN.1 "SEQUENCE OF <tag>"
 * and call a callback for each entry found.
 */
int mbedtls_asn1_traverse_sequence_of(
    unsigned char **p,
    const unsigned char *end,
    unsigned char tag_must_mask, unsigned char tag_must_val,
    unsigned char tag_may_mask, unsigned char tag_may_val,
    int (*cb)( void *ctx, int tag,
               unsigned char *start, size_t len ),
    void *ctx )
{
    int ret;
    size_t len;
    /* Get main sequence tag */
    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
    {
        return( ret );
    }
    if( *p + len != end )
        return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
    while( *p < end )
    {
        unsigned char const tag = *(*p)++;
        if( ( tag & tag_must_mask ) != tag_must_val )
            return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
        if( ( ret = mbedtls_asn1_get_len( p, end, &len ) ) != 0 )
            return( ret );
        if( ( tag & tag_may_mask ) == tag_may_val )
        {
            if( cb )
            {
                ret = cb( ctx, tag, *p, len );
                if( ret != 0 )
                    return( ret );
            }
        }
        *p += len;
    }
    return( 0 );
}

/*
 * Get a bit string without unused bits
 */
int mbedtls_asn1_get_bitstring_null( unsigned char **p,
                                     const unsigned char *end,
                                     size_t *len )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
        return( ret );
    if( !*len )
        return( MBEDTLS_ERR_ASN1_INVALID_DATA );
    --( *len );
    if( **p != 0 )
        return( MBEDTLS_ERR_ASN1_INVALID_DATA );
    ++( *p );
    return( 0 );
}

void mbedtls_asn1_sequence_free( mbedtls_asn1_sequence *seq )
{
    while( seq )
    {
        mbedtls_asn1_sequence *next = seq->next;
        mbedtls_platform_zeroize( seq, sizeof( *seq ) );
        mbedtls_free( seq );
        seq = next;
    }
}

typedef struct
{
    int tag;
    mbedtls_asn1_sequence *cur;
} asn1_get_sequence_of_cb_ctx_t;

static int asn1_get_sequence_of_cb( void *ctx,
                                    int tag,
                                    unsigned char *start,
                                    size_t len )
{
    asn1_get_sequence_of_cb_ctx_t *cb_ctx =
        (asn1_get_sequence_of_cb_ctx_t *) ctx;
    mbedtls_asn1_sequence *cur =
        cb_ctx->cur;
    if( cur->buf.p )
    {
        cur->next =
            mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
        if( !cur->next )
            return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
        cur = cur->next;
    }
    cur->buf.p = start;
    cur->buf.len = len;
    cur->buf.tag = tag;
    cb_ctx->cur = cur;
    return( 0 );
}

/*
 *  Parses and splits an ASN.1 "SEQUENCE OF <tag>"
 */
int mbedtls_asn1_get_sequence_of( unsigned char **p,
                                  const unsigned char *end,
                                  mbedtls_asn1_sequence *cur,
                                  int tag)
{
    asn1_get_sequence_of_cb_ctx_t cb_ctx = { tag, cur };
    mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_sequence ) );
    return( mbedtls_asn1_traverse_sequence_of(
                p, end, 0xFF, tag, 0, 0,
                asn1_get_sequence_of_cb, &cb_ctx ) );
}

int mbedtls_asn1_get_alg( unsigned char **p,
                          const unsigned char *end,
                          mbedtls_asn1_buf *alg,
                          mbedtls_asn1_buf *params )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    size_t len;
    if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
        return( ret );
    if( ( end - *p ) < 1 )
        return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
    alg->tag = **p;
    end = *p + len;
    if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
        return( ret );
    alg->p = *p;
    *p += alg->len;
    if( *p == end )
    {
        mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) );
        return( 0 );
    }
    params->tag = **p;
    (*p)++;
    if( ( ret = mbedtls_asn1_get_len( p, end, &params->len ) ) != 0 )
        return( ret );
    params->p = *p;
    *p += params->len;
    if( *p != end )
        return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
    return( 0 );
}

int mbedtls_asn1_get_alg_null( unsigned char **p,
                       const unsigned char *end,
                       mbedtls_asn1_buf *alg )
{
    int ret = MBEDTLS_ERR_THIS_CORRUPTION;
    mbedtls_asn1_buf params;
    mbedtls_platform_zeroize( &params, sizeof(mbedtls_asn1_buf) );
    if( ( ret = mbedtls_asn1_get_alg( p, end, alg, &params ) ) != 0 )
        return( ret );
    if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
        return( MBEDTLS_ERR_ASN1_INVALID_DATA );
    return( 0 );
}

void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
{
    if( !cur )
        return;
    mbedtls_free( cur->oid.p );
    mbedtls_free( cur->val.p );
    mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
}

void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
{
    mbedtls_asn1_named_data *cur;
    while( ( cur = *head ) )
    {
        *head = cur->next;
        mbedtls_asn1_free_named_data( cur );
        mbedtls_free( cur );
    }
}

mbedtls_asn1_named_data *
mbedtls_asn1_find_named_data(mbedtls_asn1_named_data *list,
                             const char *oid, size_t len )
{
    while( list )
    {
        if( list->oid.len == len &&
            timingsafe_bcmp( list->oid.p, oid, len ) == 0 )
        {
            break;
        }
        list = list->next;
    }
    return( list );
}

#endif /* MBEDTLS_ASN1_PARSE_C */