shinys000114/libssh
1
0
Fork 0
mirror of https://git.libssh.org/projects/libssh.git synced 2026-02-07 18:50:27 +09:00
Code Issues Packages Projects Releases Wiki Activity

chacha: packet decryption

Browse Source 
Signed-off-by: Aris Adamantiadis <aris@0xbadc0de.be>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Aris Adamantiadis
2018-02-28 10:24:54 -06:00
committed by Andreas Schneider
parent d038c4dee7
commit 8a735d5eb7
7 changed files with 275 additions and 103 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
src/packet.c
View File

@@ -144,20 +144,26 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
ssh_session session= (ssh_session) user;
unsigned int blocksize = (session->current_crypto ?
session->current_crypto->in_cipher->blocksize : 8);
unsigned char mac[DIGEST_MAX_LEN] = {0};
char buffer[16] = {0};
unsigned int lenfield_blocksize = (session->current_crypto ?
session->current_crypto->in_cipher->lenfield_blocksize : 8);
size_t current_macsize = 0;
const uint8_t *packet;
uint8_t *ptr = NULL;
int to_be_read;
int rc;
uint32_t len, compsize, payloadsize;
uint8_t *cleartext_packet = NULL;
uint8_t *packet_second_block = NULL;
uint8_t *mac = NULL;
size_t packet_remaining;
uint32_t packet_len, compsize, payloadsize;
uint8_t padding;
size_t processed = 0; /* number of byte processed from the callback */
if(session->current_crypto != NULL) {
current_macsize = hmac_digest_len(session->current_crypto->in_hmac);
}
if (lenfield_blocksize == 0) {
lenfield_blocksize = blocksize;
}
if (data == NULL) {
goto error;
}
@@ -178,7 +184,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
#endif
switch(session->packet_state) {
case PACKET_STATE_INIT:
if (receivedlen < blocksize) {
if (receivedlen < lenfield_blocksize) {
/*
* We didn't receive enough data to read at least one
* block size, give up
@@ -187,7 +193,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
SSH_LOG(SSH_LOG_PACKET,
"Waiting for more data (%zu < %zu)",
receivedlen,
blocksize);
lenfield_blocksize);
#endif
return 0;
}
@@ -206,24 +212,21 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
}
}
memcpy(buffer, data, blocksize);
processed += blocksize;
len = ssh_packet_decrypt_len(session, buffer);
rc = ssh_buffer_add_data(session->in_buffer, buffer, blocksize);
if (rc < 0) {
ptr = ssh_buffer_allocate(session->in_buffer, lenfield_blocksize);
if (ptr == NULL) {
goto error;
}
processed += lenfield_blocksize;
packet_len = ssh_packet_decrypt_len(session, ptr, (uint8_t *)data);
if (len > MAX_PACKET_LEN) {
if (packet_len > MAX_PACKET_LEN) {
ssh_set_error(session,
SSH_FATAL,
"read_packet(): Packet len too high(%u %.4x)",
len, len);
packet_len, packet_len);
goto error;
}
to_be_read = len - blocksize + sizeof(uint32_t);
to_be_read = packet_len - lenfield_blocksize + sizeof(uint32_t);
if (to_be_read < 0) {
/* remote sshd sends invalid sizes? */
ssh_set_error(session,
@@ -233,59 +236,52 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
goto error;
}
/* Saves the status of the current operations */
session->in_packet.len = len;
session->in_packet.len = packet_len;
session->packet_state = PACKET_STATE_SIZEREAD;
FALL_THROUGH;
case PACKET_STATE_SIZEREAD:
len = session->in_packet.len;
to_be_read = len - blocksize + sizeof(uint32_t) + current_macsize;
packet_len = session->in_packet.len;
processed = lenfield_blocksize;
to_be_read = packet_len + sizeof(uint32_t) + current_macsize;
/* if to_be_read is zero, the whole packet was blocksize bytes. */
if (to_be_read != 0) {
if (receivedlen - processed < (unsigned int)to_be_read) {
if (receivedlen < (unsigned int)to_be_read) {
/* give up, not enough data in buffer */
SSH_LOG(SSH_LOG_PACKET,"packet: partial packet (read len) [len=%d]",len);
return processed;
SSH_LOG(SSH_LOG_PACKET,
"packet: partial packet (read len) "
"[len=%d, receivedlen=%d, to_be_read=%d]",
packet_len,
(int)receivedlen,
to_be_read);
return 0;
}
packet = ((uint8_t*)data) + processed;
#if 0
ssh_socket_read(session->socket,
packet,
to_be_read - current_macsize);
#endif
rc = ssh_buffer_add_data(session->in_buffer,
packet,
to_be_read - current_macsize);
if (rc < 0) {
goto error;
}
processed += to_be_read - current_macsize;
packet_second_block = (uint8_t*)data + lenfield_blocksize;
processed = to_be_read - current_macsize;
}
/* remaining encrypted bytes from the packet, MAC not included */
packet_remaining =
packet_len - (lenfield_blocksize - sizeof(uint32_t));
cleartext_packet = ssh_buffer_allocate(session->in_buffer,
packet_remaining);
if (session->current_crypto) {
/*
* Decrypt the rest of the packet (blocksize bytes already
* Decrypt the rest of the packet (lenfield_blocksize bytes already
* have been decrypted)
*/
uint32_t buffer_len = ssh_buffer_get_len(session->in_buffer);
/* The following check avoids decrypting zero bytes */
if (buffer_len > blocksize) {
uint8_t *payload = ((uint8_t*)ssh_buffer_get(session->in_buffer) + blocksize);
uint32_t plen = buffer_len - blocksize;
rc = ssh_packet_decrypt(session, payload, plen);
if (packet_remaining > 0) {
rc = ssh_packet_decrypt(session,
cleartext_packet,
(uint8_t *)data,
lenfield_blocksize,
processed - lenfield_blocksize);
if (rc < 0) {
ssh_set_error(session, SSH_FATAL, "Decrypt error");
ssh_set_error(session, SSH_FATAL, "Decryption error");
goto error;
}
}
/* copy the last part from the incoming buffer */
packet = ((uint8_t *)data) + processed;
memcpy(mac, packet, current_macsize);
mac = packet_second_block + packet_remaining;
rc = ssh_packet_hmac_verify(session, session->in_buffer, mac, session->current_crypto->in_hmac);
if (rc < 0) {
@@ -293,6 +289,8 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
goto error;
}
processed += current_macsize;
} else {
memcpy(cleartext_packet, packet_second_block, packet_remaining);
}
/* skip the size field which has been processed before */
@@ -342,7 +340,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
ssh_packet_parse_type(session);
SSH_LOG(SSH_LOG_PACKET,
"packet: read type %hhd [len=%d,padding=%hhd,comp=%d,payload=%d]",
session->in_packet.type, len, padding, compsize, payloadsize);
session->in_packet.type, packet_len, padding, compsize, payloadsize);
/* Execute callbacks */
ssh_packet_process(session, session->in_packet.type);
@@ -353,9 +351,9 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
"Processing %" PRIdS " bytes left in socket buffer",
receivedlen-processed);
packet = ((uint8_t*)data) + processed;
ptr = ((uint8_t*)data) + processed;
rc = ssh_packet_socket_callback(packet, receivedlen - processed,user);
rc = ssh_packet_socket_callback(ptr, receivedlen - processed,user);
processed += rc;
}
@@ -372,7 +370,7 @@ int ssh_packet_socket_callback(const void *data, size_t receivedlen, void *user)
error:
session->session_state= SSH_SESSION_STATE_ERROR;
SSH_LOG(SSH_LOG_PACKET,"Packet: processed %" PRIdS " bytes", processed);
return processed;
}