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Commit 8ea1d55b authored by Jan Včelák's avatar Jan Včelák :rocket:
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DNSSEC: check boundaries when writing signature

parent c0b6581b
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1 merge request!111DNSSEC: support for GOST
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src/libknot/dnssec/sign.c
+ 154
− 84
View file @ 8ea1d55b
......@@ -62,7 +62,7 @@ struct algorithm_functions {
//! \brief Callback: cover supplied data with the signature.
int (*sign_add)(const knot_dnssec_sign_context_t *, const uint8_t *, size_t);
//! \brief Callback: finish the signing and write out the signature.
int (*sign_write)(const knot_dnssec_sign_context_t *, uint8_t *);
int (*sign_write)(const knot_dnssec_sign_context_t *, uint8_t *, size_t);
//! \brief Callback: finish the signing and validate the signature.
int (*sign_verify)(const knot_dnssec_sign_context_t *, const uint8_t *, size_t);
};
......@@ -122,45 +122,114 @@ static int any_sign_add(const knot_dnssec_sign_context_t *context,
}
/*!
* \brief Finish the signing and get the RAW signature.
* \brief Finish the signing and write the signature while checking boundaries.
*
* Caller should free the memory returned via signature parameter.
*
* \param context DNSSEC signature context.
* \param signature Pointer to signature (output).
* \param signature_size Signature size (output).
* \param context DNSSEC signing context.
* \param signature Pointer to signature to be written.
* \param max_size Maximal size of the signature.
* \param size Actual size of written signature.
*
* \return Error code, KNOT_EOK if successful.
*/
static int any_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t **signature, size_t *signature_size)
static int sign_safe_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature, size_t max_size, size_t *size)
{
assert(context);
assert(signature);
assert(signature_size);
assert(size);
size_t max_size = (size_t)EVP_PKEY_size(context->key->data->private_key);
uint8_t *output = calloc(1, max_size);
if (!output) {
return KNOT_ENOMEM;
EVP_MD_CTX *digest_ctx = context->digest_context;
EVP_PKEY *private_key = context->key->data->private_key;
// check target size
unsigned int max_write = 0;
int result = EVP_SignFinal(digest_ctx, NULL, &max_write, private_key);
if (!result) {
return KNOT_DNSSEC_ESIGN;
}
if (max_write > max_size) {
return KNOT_DNSSEC_EUNEXPECTED_SIGNATURE_SIZE;
}
unsigned int actual_size;
int result = EVP_SignFinal(context->digest_context, output,
&actual_size, context->key->data->private_key);
// write signature
unsigned int written = 0;
result = EVP_SignFinal(digest_ctx, signature, &written, private_key);
if (!result) {
free(output);
return KNOT_DNSSEC_ESIGN;
}
assert(actual_size <= max_size);
assert(written <= max_write);
*size = written;
return KNOT_EOK;
}
/*!
* \brief Allocate space for signature, finish signature, and write it.
*
* \param context DNSSEC signing context.
* \param signature Pointer to allocated signature.
* \param size Size of the written signature.
*
* \return Error code, KNOT_EOK if successful.
*/
static int sign_alloc_and_write(const knot_dnssec_sign_context_t *context,
uint8_t **signature, size_t *size)
{
assert(context);
assert(signature);
assert(size);
size_t buffer_size = EVP_PKEY_size(context->key->data->private_key);
uint8_t *buffer = malloc(buffer_size);
if (!buffer) {
return KNOT_ENOMEM;
}
size_t written = 0;
int result = sign_safe_write(context, buffer, buffer_size, &written);
if (result != KNOT_EOK) {
free(buffer);
return result;
}
assert(written <= buffer_size);
*signature = output;
*signature_size = actual_size;
*signature = buffer;
*size = written;
return KNOT_EOK;
}
/*!
* \brief Finish the signing and write out the signature.
*
* \note Expects algorithm whose signature size is constant.
*
* \param context DNSSEC signing context.
* \param signature Pointer to memory where the signature will be written.
* \param signature_size Expected size of the signature.
*
* \return Error code, KNOT_EOK if successful.
*/
static int any_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature, size_t signature_size)
{
assert(context);
assert(signature);
size_t written_size = 0;
int result = sign_safe_write(context, signature,
signature_size, &written_size);
assert(written_size == signature_size);
return result;
}
/*!
* \brief Verify the DNSSEC signature for supplied data.
*
......@@ -193,6 +262,32 @@ static int any_sign_verify(const knot_dnssec_sign_context_t *context,
};
}
/*!
* \brief Get pointer to and size of public key in DNSKEY RDATA.
*
* \param[in] rdata DNSKEY RDATA.
* \param[out] pubkey Public key.
* \param[out] pubkey_size Size of public key.
*
* \return Success.
*/
static bool any_dnskey_get_pubkey(const knot_binary_t *rdata,
const uint8_t **pubkey, size_t *pubkey_size)
{
assert(rdata);
assert(pubkey);
assert(pubkey_size);
if (rdata->size <= DNSKEY_RDATA_PUBKEY_OFFSET) {
return false;
}
*pubkey = rdata->data + DNSKEY_RDATA_PUBKEY_OFFSET;
*pubkey_size = rdata->size - DNSKEY_RDATA_PUBKEY_OFFSET;
return true;
}
/*- RSA specific -------------------------------------------------------------*/
/*!
......@@ -235,41 +330,6 @@ static int rsa_create_pkey(const knot_key_params_t *params, EVP_PKEY *key)
return KNOT_EOK;
}
/*!
* \brief Finish the signing and write out the RSA signature.
*
* \param context DNSSEC signing context.
* \param signature Pointer to memory where the signature will be written.
*
* \return Error code, KNOT_EOK if successful.
*/
static int rsa_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature)
{
assert(context);
assert(signature);
int result;
uint8_t *raw_signature;
size_t raw_signature_size;
const knot_dnssec_key_t *key = context->key;
result = any_sign_write(context, &raw_signature, &raw_signature_size);
if (result != KNOT_EOK) {
return result;
}
if (raw_signature_size != key->data->functions->sign_size(key)) {
free(raw_signature);
return KNOT_DNSSEC_EUNEXPECTED_SIGNATURE_SIZE;
}
memcpy(signature, raw_signature, raw_signature_size);
free(raw_signature);
return KNOT_EOK;
}
/*- DSA specific -------------------------------------------------------------*/
/*!
......@@ -313,19 +373,24 @@ static size_t dsa_sign_size(const knot_dnssec_key_t *key)
/*!
* \brief Finish the signing and write out the DSA signature.
* \see rsa_sign_write
* \see any_sign_write
*/
static int dsa_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature)
uint8_t *signature, size_t signature_size)
{
assert(context);
assert(signature);
int result;
uint8_t *raw_signature;
size_t raw_signature_size;
size_t output_size = dsa_sign_size(context->key);
if (output_size != signature_size) {
return KNOT_DNSSEC_EUNEXPECTED_SIGNATURE_SIZE;
}
// create raw signature
result = any_sign_write(context, &raw_signature, &raw_signature_size);
uint8_t *raw_signature = NULL;
size_t raw_size = 0;
int result = sign_alloc_and_write(context, &raw_signature, &raw_size);
if (result != KNOT_EOK) {
return result;
}
......@@ -339,7 +404,7 @@ static int dsa_sign_write(const knot_dnssec_sign_context_t *context,
}
const uint8_t *decode_scan = raw_signature;
if (!d2i_DSA_SIG(&decoded, &decode_scan, (long)raw_signature_size)) {
if (!d2i_DSA_SIG(&decoded, &decode_scan, (long)raw_size)) {
DSA_SIG_free(decoded);
free(raw_signature);
return KNOT_DNSSEC_EDECODE_RAW_SIGNATURE;
......@@ -354,7 +419,7 @@ static int dsa_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature_r = signature + 21 - BN_num_bytes(decoded->r);
uint8_t *signature_s = signature + 41 - BN_num_bytes(decoded->s);
memset(signature, '\0', dsa_sign_size(context->key));
memset(signature, '\0', output_size);
*signature_t = 0x00; //! \todo Take from public key. Only recommended.
BN_bn2bin(decoded->r, signature_r);
BN_bn2bin(decoded->s, signature_s);
......@@ -429,20 +494,19 @@ static int ecdsa_set_public_key(const knot_binary_t *rdata, EC_KEY *ec_key)
assert(rdata);
assert(ec_key);
if (rdata->size <= DNSKEY_RDATA_PUBKEY_OFFSET) {
const uint8_t *pubkey_data = NULL;
size_t pubkey_size = 0;
if (!any_dnskey_get_pubkey(rdata, &pubkey_data, &pubkey_size)) {
return KNOT_EINVAL;
}
uint8_t *pubkey_data = rdata->data + DNSKEY_RDATA_PUBKEY_OFFSET;
size_t pubkey_size = rdata->size - DNSKEY_RDATA_PUBKEY_OFFSET;
if (pubkey_size % 2 != 0) {
return KNOT_EINVAL;
}
size_t param_size = pubkey_size / 2;
uint8_t *x_ptr = pubkey_data;
uint8_t *y_ptr = pubkey_data + param_size;
const uint8_t *x_ptr = pubkey_data;
const uint8_t *y_ptr = pubkey_data + param_size;
BIGNUM *x = BN_bin2bn(x_ptr, param_size, NULL);
BIGNUM *y = BN_bin2bn(y_ptr, param_size, NULL);
......@@ -541,16 +605,21 @@ static size_t ecdsa_sign_size(const knot_dnssec_key_t *key)
* \see rsa_sign_write
*/
static int ecdsa_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature)
uint8_t *signature, size_t signature_size)
{
assert(context);
assert(signature);
int result;
uint8_t *raw_signature;
size_t raw_signature_size;
size_t output_size = ecdsa_sign_size(context->key);
if (output_size != signature_size) {
return KNOT_DNSSEC_EUNEXPECTED_SIGNATURE_SIZE;
}
// create raw signature
result = any_sign_write(context, &raw_signature, &raw_signature_size);
uint8_t *raw_signature = NULL;
size_t raw_size = 0;
int result = sign_alloc_and_write(context, &raw_signature, &raw_size);
if (result != KNOT_EOK) {
return result;
}
......@@ -564,7 +633,7 @@ static int ecdsa_sign_write(const knot_dnssec_sign_context_t *context,
}
const uint8_t *decode_scan = raw_signature;
if (!d2i_ECDSA_SIG(&decoded, &decode_scan, (long)raw_signature_size)) {
if (!d2i_ECDSA_SIG(&decoded, &decode_scan, (long)raw_size)) {
ECDSA_SIG_free(decoded);
free(raw_signature);
return KNOT_DNSSEC_EDECODE_RAW_SIGNATURE;
......@@ -577,10 +646,9 @@ static int ecdsa_sign_write(const knot_dnssec_sign_context_t *context,
uint8_t *signature_r;
uint8_t *signature_s;
size_t signature_size = ecdsa_sign_size(context->key);
size_t param_size = signature_size / 2;
size_t param_size = output_size / 2;
memset(signature, '\0', signature_size);
memset(signature, '\0', output_size);
signature_r = signature + param_size - BN_num_bytes(decoded->r);
signature_s = signature + 2 * param_size - BN_num_bytes(decoded->s);
......@@ -654,7 +722,7 @@ static const algorithm_functions_t rsa_functions = {
rsa_create_pkey,
any_sign_size,
any_sign_add,
rsa_sign_write,
any_sign_write,
any_sign_verify
};
......@@ -697,9 +765,9 @@ static const algorithm_functions_t *get_implementation(int algorithm)
case KNOT_DNSSEC_ALG_DSA:
case KNOT_DNSSEC_ALG_DSA_NSEC3_SHA1:
return &dsa_functions;
#ifdef KNOT_ENABLE_ECDSA
case KNOT_DNSSEC_ALG_ECDSAP256SHA256:
case KNOT_DNSSEC_ALG_ECDSAP384SHA384:
#ifdef KNOT_ENABLE_ECDSA
return &ecdsa_functions;
#endif
default:
......@@ -1049,13 +1117,15 @@ int knot_dnssec_sign_add(knot_dnssec_sign_context_t *context,
/**
* \brief Write down the DNSSEC signature for supplied data.
*/
int knot_dnssec_sign_write(knot_dnssec_sign_context_t *context, uint8_t *signature)
int knot_dnssec_sign_write(knot_dnssec_sign_context_t *context,
uint8_t *signature, size_t signature_size)
{
if (!context || !context->key || !signature) {
if (!context || !context->key || !signature || signature_size == 0) {
return KNOT_EINVAL;
}
return context->key->data->functions->sign_write(context, signature);
return context->key->data->functions->sign_write(context, signature,
signature_size);
}
/**
......
src/libknot/dnssec/sign.h
+ 4
− 3
View file @ 8ea1d55b
......@@ -132,13 +132,14 @@ int knot_dnssec_sign_add(knot_dnssec_sign_context_t *context,
/**
* \brief Write down the DNSSEC signature for supplied data.
*
* \param context DNSSEC signing context.
* \param signature Pointer to signature to be written.
* \param context DNSSEC signing context.
* \param signature Pointer to signature to be written.
* \param signature_size Allocated size for the signature.
*
* \return Error code, KNOT_EOK if successful.
*/
int knot_dnssec_sign_write(knot_dnssec_sign_context_t *context,
uint8_t *signature);
uint8_t *signature, size_t signature_size);
/**
* \brief Verify the DNSSEC signature for supplied data.
......
tests/dnssec_sign.c
+ 1
− 1
View file @ 8ea1d55b
......@@ -58,7 +58,7 @@ static void test_algorithm(const char *alg, const knot_key_params_t *kp)
result = knot_dnssec_sign_add(ctx, (uint8_t *)"dns", 3);
is_int(KNOT_EOK, result, "%s: add data C", alg);
result = knot_dnssec_sign_write(ctx, sig);
result = knot_dnssec_sign_write(ctx, sig, sig_size);
is_int(KNOT_EOK, result, "%s: write signature", alg);
result = knot_dnssec_sign_new(ctx);
......
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