| /* |
| * ASN.1 buffer writing functionality |
| * |
| * Copyright The Mbed TLS Contributors |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * 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 "common.h" |
| |
| #if defined(MBEDTLS_ASN1_WRITE_C) |
| |
| #include "mbedtls/asn1write.h" |
| #include "mbedtls/error.h" |
| |
| #include <string.h> |
| |
| #if defined(MBEDTLS_PLATFORM_C) |
| #include "mbedtls/platform.h" |
| #else |
| #include <stdlib.h> |
| #define mbedtls_calloc calloc |
| #define mbedtls_free free |
| #endif |
| |
| int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len ) |
| { |
| if( len < 0x80 ) |
| { |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = (unsigned char) len; |
| return( 1 ); |
| } |
| |
| if( len <= 0xFF ) |
| { |
| if( *p - start < 2 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = (unsigned char) len; |
| *--(*p) = 0x81; |
| return( 2 ); |
| } |
| |
| if( len <= 0xFFFF ) |
| { |
| if( *p - start < 3 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = ( len ) & 0xFF; |
| *--(*p) = ( len >> 8 ) & 0xFF; |
| *--(*p) = 0x82; |
| return( 3 ); |
| } |
| |
| if( len <= 0xFFFFFF ) |
| { |
| if( *p - start < 4 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = ( len ) & 0xFF; |
| *--(*p) = ( len >> 8 ) & 0xFF; |
| *--(*p) = ( len >> 16 ) & 0xFF; |
| *--(*p) = 0x83; |
| return( 4 ); |
| } |
| |
| #if SIZE_MAX > 0xFFFFFFFF |
| if( len <= 0xFFFFFFFF ) |
| #endif |
| { |
| if( *p - start < 5 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = ( len ) & 0xFF; |
| *--(*p) = ( len >> 8 ) & 0xFF; |
| *--(*p) = ( len >> 16 ) & 0xFF; |
| *--(*p) = ( len >> 24 ) & 0xFF; |
| *--(*p) = 0x84; |
| return( 5 ); |
| } |
| |
| #if SIZE_MAX > 0xFFFFFFFF |
| return( MBEDTLS_ERR_ASN1_INVALID_LENGTH ); |
| #endif |
| } |
| |
| int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag ) |
| { |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = tag; |
| |
| return( 1 ); |
| } |
| |
| int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start, |
| const unsigned char *buf, size_t size ) |
| { |
| size_t len = 0; |
| |
| if( *p < start || (size_t)( *p - start ) < size ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| len = size; |
| (*p) -= len; |
| memcpy( *p, buf, len ); |
| |
| return( (int) len ); |
| } |
| |
| #if defined(MBEDTLS_BIGNUM_C) |
| int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| // Write the MPI |
| // |
| len = mbedtls_mpi_size( X ); |
| |
| if( *p < start || (size_t)( *p - start ) < len ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| (*p) -= len; |
| MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) ); |
| |
| // DER format assumes 2s complement for numbers, so the leftmost bit |
| // should be 0 for positive numbers and 1 for negative numbers. |
| // |
| if( X->s ==1 && **p & 0x80 ) |
| { |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = 0x00; |
| len += 1; |
| } |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) ); |
| |
| ret = (int) len; |
| |
| cleanup: |
| return( ret ); |
| } |
| #endif /* MBEDTLS_BIGNUM_C */ |
| |
| int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| // Write NULL |
| // |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start, |
| const char *oid, size_t oid_len ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, |
| (const unsigned char *) oid, oid_len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start, |
| const char *oid, size_t oid_len, |
| size_t par_len ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| if( par_len == 0 ) |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) ); |
| else |
| len += par_len; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) ); |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, |
| MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| *--(*p) = (boolean) ? 255 : 0; |
| len++; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) ); |
| |
| return( (int) len ); |
| } |
| |
| static int asn1_write_tagged_int( unsigned char **p, unsigned char *start, int val, int tag ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| do |
| { |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| len += 1; |
| *--(*p) = val & 0xff; |
| val >>= 8; |
| } |
| while( val > 0 ); |
| |
| if( **p & 0x80 ) |
| { |
| if( *p - start < 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| *--(*p) = 0x00; |
| len += 1; |
| } |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val ) |
| { |
| return( asn1_write_tagged_int( p, start, val, MBEDTLS_ASN1_INTEGER ) ); |
| } |
| |
| int mbedtls_asn1_write_enum( unsigned char **p, unsigned char *start, int val ) |
| { |
| return( asn1_write_tagged_int( p, start, val, MBEDTLS_ASN1_ENUMERATED ) ); |
| } |
| |
| int mbedtls_asn1_write_tagged_string( unsigned char **p, unsigned char *start, int tag, |
| const char *text, size_t text_len ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, |
| (const unsigned char *) text, text_len ) ); |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start, |
| const char *text, size_t text_len ) |
| { |
| return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) ); |
| } |
| |
| int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start, |
| const char *text, size_t text_len ) |
| { |
| return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) ); |
| } |
| |
| int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start, |
| const char *text, size_t text_len ) |
| { |
| return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) ); |
| } |
| |
| int mbedtls_asn1_write_named_bitstring( unsigned char **p, |
| unsigned char *start, |
| const unsigned char *buf, |
| size_t bits ) |
| { |
| size_t unused_bits, byte_len; |
| const unsigned char *cur_byte; |
| unsigned char cur_byte_shifted; |
| unsigned char bit; |
| |
| byte_len = ( bits + 7 ) / 8; |
| unused_bits = ( byte_len * 8 ) - bits; |
| |
| /* |
| * Named bitstrings require that trailing 0s are excluded in the encoding |
| * of the bitstring. Trailing 0s are considered part of the 'unused' bits |
| * when encoding this value in the first content octet |
| */ |
| if( bits != 0 ) |
| { |
| cur_byte = buf + byte_len - 1; |
| cur_byte_shifted = *cur_byte >> unused_bits; |
| |
| for( ; ; ) |
| { |
| bit = cur_byte_shifted & 0x1; |
| cur_byte_shifted >>= 1; |
| |
| if( bit != 0 ) |
| break; |
| |
| bits--; |
| if( bits == 0 ) |
| break; |
| |
| if( bits % 8 == 0 ) |
| cur_byte_shifted = *--cur_byte; |
| } |
| } |
| |
| return( mbedtls_asn1_write_bitstring( p, start, buf, bits ) ); |
| } |
| |
| int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start, |
| const unsigned char *buf, size_t bits ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| size_t unused_bits, byte_len; |
| |
| byte_len = ( bits + 7 ) / 8; |
| unused_bits = ( byte_len * 8 ) - bits; |
| |
| if( *p < start || (size_t)( *p - start ) < byte_len + 1 ) |
| return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); |
| |
| len = byte_len + 1; |
| |
| /* Write the bitstring. Ensure the unused bits are zeroed */ |
| if( byte_len > 0 ) |
| { |
| byte_len--; |
| *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 ); |
| ( *p ) -= byte_len; |
| memcpy( *p, buf, byte_len ); |
| } |
| |
| /* Write unused bits */ |
| *--( *p ) = (unsigned char)unused_bits; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) ); |
| |
| return( (int) len ); |
| } |
| |
| int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start, |
| const unsigned char *buf, size_t size ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| size_t len = 0; |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) ); |
| |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); |
| MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) ); |
| |
| return( (int) len ); |
| } |
| |
| |
| /* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(), |
| * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */ |
| static mbedtls_asn1_named_data *asn1_find_named_data( |
| mbedtls_asn1_named_data *list, |
| const char *oid, size_t len ) |
| { |
| while( list != NULL ) |
| { |
| if( list->oid.len == len && |
| memcmp( list->oid.p, oid, len ) == 0 ) |
| { |
| break; |
| } |
| |
| list = list->next; |
| } |
| |
| return( list ); |
| } |
| |
| mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( |
| mbedtls_asn1_named_data **head, |
| const char *oid, size_t oid_len, |
| const unsigned char *val, |
| size_t val_len ) |
| { |
| mbedtls_asn1_named_data *cur; |
| |
| if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL ) |
| { |
| // Add new entry if not present yet based on OID |
| // |
| cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1, |
| sizeof(mbedtls_asn1_named_data) ); |
| if( cur == NULL ) |
| return( NULL ); |
| |
| cur->oid.len = oid_len; |
| cur->oid.p = mbedtls_calloc( 1, oid_len ); |
| if( cur->oid.p == NULL ) |
| { |
| mbedtls_free( cur ); |
| return( NULL ); |
| } |
| |
| memcpy( cur->oid.p, oid, oid_len ); |
| |
| cur->val.len = val_len; |
| if( val_len != 0 ) |
| { |
| cur->val.p = mbedtls_calloc( 1, val_len ); |
| if( cur->val.p == NULL ) |
| { |
| mbedtls_free( cur->oid.p ); |
| mbedtls_free( cur ); |
| return( NULL ); |
| } |
| } |
| |
| cur->next = *head; |
| *head = cur; |
| } |
| else if( val_len == 0 ) |
| { |
| mbedtls_free( cur->val.p ); |
| cur->val.p = NULL; |
| } |
| else if( cur->val.len != val_len ) |
| { |
| /* |
| * Enlarge existing value buffer if needed |
| * Preserve old data until the allocation succeeded, to leave list in |
| * a consistent state in case allocation fails. |
| */ |
| void *p = mbedtls_calloc( 1, val_len ); |
| if( p == NULL ) |
| return( NULL ); |
| |
| mbedtls_free( cur->val.p ); |
| cur->val.p = p; |
| cur->val.len = val_len; |
| } |
| |
| if( val != NULL ) |
| memcpy( cur->val.p, val, val_len ); |
| |
| return( cur ); |
| } |
| #endif /* MBEDTLS_ASN1_WRITE_C */ |