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Merge pull request #263 from hanno-arm/asn1_traversal_api

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Introduce ASN.1 SEQUENCE traversal API
This commit is contained in:
Gilles Peskine
2020-02-03 13:35:19 +01:00
committed by GitHub
parent c0611a5a61 34aada2df5
commit c69c2c5bf5
4 changed files with 379 additions and 52 deletions
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144
library/asn1parse.c
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@ -247,6 +247,58 @@ int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
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 != NULL )
{
ret = cb( ctx, tag, *p, len );
if( ret != 0 )
return( ret );
}
}
*p += len;
}
return( 0 );
}
/*
* Get a bit string without unused bits
*/
@ -269,7 +321,51 @@ int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end
return( 0 );
}
void mbedtls_asn1_sequence_free( mbedtls_asn1_sequence *seq )
{
while( seq != NULL )
{
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 != NULL )
{
cur->next =
mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
if( cur->next == NULL )
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>"
@ -279,49 +375,11 @@ int mbedtls_asn1_get_sequence_of( unsigned char **p,
mbedtls_asn1_sequence *cur,
int tag)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
mbedtls_asn1_buf *buf;
/* 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 )
{
buf = &(cur->buf);
buf->tag = **p;
if( ( ret = mbedtls_asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
return( ret );
buf->p = *p;
*p += buf->len;
/* Allocate and assign next pointer */
if( *p < end )
{
cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
sizeof( mbedtls_asn1_sequence ) );
if( cur->next == NULL )
return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
cur = cur->next;
}
}
/* Set final sequence entry's next pointer to NULL */
cur->next = NULL;
if( *p != end )
return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
return( 0 );
asn1_get_sequence_of_cb_ctx_t cb_ctx = { tag, cur };
memset( cur, 0, 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,