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packet: Skip HMAC handling if none is selected

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Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Jakub Jelen
2020-04-28 13:09:11 +02:00
committed by Andreas Schneider
parent 239eef6322
commit 4f976ce5c4
2 changed files with 29 additions and 22 deletions
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7
src/packet.c
View File

@@ -1213,7 +1213,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
if (crypto != NULL) {
mac = packet_second_block + packet_remaining;
if (etm) {
if (crypto->in_hmac != SSH_HMAC_NONE && etm) {
rc = ssh_packet_hmac_verify(session,
data,
processed,
@@ -1243,7 +1243,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
}
}
if (!etm) {
if (crypto->in_hmac != SSH_HMAC_NONE && !etm) {
rc = ssh_packet_hmac_verify(session,
ssh_buffer_get(session->in_buffer),
ssh_buffer_get_len(session->in_buffer),
@@ -1684,6 +1684,9 @@ static int packet_send2(ssh_session session)
hmac = ssh_packet_encrypt(session,
ssh_buffer_get(session->out_buffer),
ssh_buffer_get_len(session->out_buffer));
/* XXX This returns null before switching on crypto, with none MAC
* and on various errors.
* We should distinguish between these cases to avoid hiding errors. */
if (hmac != NULL) {
rc = ssh_buffer_add_data(session->out_buffer,
hmac,

44
src/packet_crypt.c
View File

@@ -177,34 +177,38 @@ unsigned char *ssh_packet_encrypt(ssh_session session, void *data, uint32_t len)
crypto->hmacbuf, session->send_seq);
memcpy(data, out, len);
} else {
ctx = hmac_init(crypto->encryptMAC, hmac_digest_len(type), type);
if (ctx == NULL) {
SAFE_FREE(out);
return NULL;
}
if (type != SSH_HMAC_NONE) {
ctx = hmac_init(crypto->encryptMAC, hmac_digest_len(type), type);
if (ctx == NULL) {
SAFE_FREE(out);
return NULL;
}
if (!etm) {
hmac_update(ctx, (unsigned char *)&seq, sizeof(uint32_t));
hmac_update(ctx, data, len);
hmac_final(ctx, crypto->hmacbuf, &finallen);
if (!etm) {
hmac_update(ctx, (unsigned char *)&seq, sizeof(uint32_t));
hmac_update(ctx, data, len);
hmac_final(ctx, crypto->hmacbuf, &finallen);
}
}
cipher->encrypt(cipher, (uint8_t*)data + etm_packet_offset, out, len - etm_packet_offset);
memcpy((uint8_t*)data + etm_packet_offset, out, len - etm_packet_offset);
if (etm) {
PUSH_BE_U32(data, 0, len - etm_packet_offset);
hmac_update(ctx, (unsigned char *)&seq, sizeof(uint32_t));
hmac_update(ctx, data, len);
hmac_final(ctx, crypto->hmacbuf, &finallen);
}
if (type != SSH_HMAC_NONE) {
if (etm) {
PUSH_BE_U32(data, 0, len - etm_packet_offset);
hmac_update(ctx, (unsigned char *)&seq, sizeof(uint32_t));
hmac_update(ctx, data, len);
hmac_final(ctx, crypto->hmacbuf, &finallen);
}
#ifdef DEBUG_CRYPTO
ssh_log_hexdump("mac: ", data, len);
if (finallen != hmac_digest_len(type)) {
printf("Final len is %d\n", finallen);
}
ssh_log_hexdump("Packet hmac", crypto->hmacbuf, hmac_digest_len(type));
ssh_log_hexdump("mac: ", data, len);
if (finallen != hmac_digest_len(type)) {
printf("Final len is %d\n", finallen);
}
ssh_log_hexdump("Packet hmac", crypto->hmacbuf, hmac_digest_len(type));
#endif
}
}
explicit_bzero(out, len);
SAFE_FREE(out);