Пример #1
0
/** @internal
 * @handles a data received event. It then calls the handlers for the different packet types
 * or and exception handler callback.
 * @param user pointer to current ssh_session
 * @param data pointer to the data received
 * @len length of data received. It might not be enough for a complete packet
 * @returns number of bytes read and processed.
 */
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 int lenfield_blocksize = (session->current_crypto ?
                                  session->current_crypto->in_cipher->lenfield_blocksize : 8);
    size_t current_macsize = 0;
    uint8_t *ptr = NULL;
    int to_be_read;
    int rc;
    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;
    }

    if (session->session_state == SSH_SESSION_STATE_ERROR) {
        goto error;
    }
#ifdef DEBUG_PACKET
    SSH_LOG(SSH_LOG_PACKET,
            "rcv packet cb (len=%zu, state=%s)",
            receivedlen,
            session->packet_state == PACKET_STATE_INIT ?
                "INIT" :
                session->packet_state == PACKET_STATE_SIZEREAD ?
                    "SIZE_READ" :
                    session->packet_state == PACKET_STATE_PROCESSING ?
                    "PROCESSING" : "unknown");
#endif
    switch(session->packet_state) {
        case PACKET_STATE_INIT:
            if (receivedlen < lenfield_blocksize) {
                /*
                 * We didn't receive enough data to read at least one
                 * block size, give up
                 */
#ifdef DEBUG_PACKET
                SSH_LOG(SSH_LOG_PACKET,
                        "Waiting for more data (%zu < %u)",
                        receivedlen,
                        lenfield_blocksize);
#endif
                return 0;
            }

            memset(&session->in_packet, 0, sizeof(PACKET));

            if (session->in_buffer) {
                rc = ssh_buffer_reinit(session->in_buffer);
                if (rc < 0) {
                    goto error;
                }
            } else {
                session->in_buffer = ssh_buffer_new();
                if (session->in_buffer == NULL) {
                    goto error;
                }
            }

            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 (packet_len > MAX_PACKET_LEN) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "read_packet(): Packet len too high(%u %.4x)",
                              packet_len, packet_len);
                goto error;
            }
            to_be_read = packet_len - lenfield_blocksize + sizeof(uint32_t);
            if (to_be_read < 0) {
                /* remote sshd sends invalid sizes? */
                ssh_set_error(session,
                              SSH_FATAL,
                              "Given numbers of bytes left to be read < 0 (%d)!",
                              to_be_read);
                goto error;
            }

            session->in_packet.len = packet_len;
            session->packet_state = PACKET_STATE_SIZEREAD;
            FALL_THROUGH;
        case PACKET_STATE_SIZEREAD:
            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  < (unsigned int)to_be_read) {
                    /* give up, not enough data in buffer */
                    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_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 (lenfield_blocksize bytes already
                 * have been decrypted)
                 */
                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, "Decryption error");
                        goto error;
                    }
                }
                mac = packet_second_block + packet_remaining;

                rc = ssh_packet_hmac_verify(session, session->in_buffer, mac, session->current_crypto->in_hmac);
                if (rc < 0) {
                    ssh_set_error(session, SSH_FATAL, "HMAC error");
                    goto error;
                }
                processed += current_macsize;
            } else {
                memcpy(cleartext_packet, packet_second_block, packet_remaining);
            }

            /* skip the size field which has been processed before */
            ssh_buffer_pass_bytes(session->in_buffer, sizeof(uint32_t));

            rc = ssh_buffer_get_u8(session->in_buffer, &padding);
            if (rc == 0) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "Packet too short to read padding");
                goto error;
            }

            if (padding > ssh_buffer_get_len(session->in_buffer)) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "Invalid padding: %d (%d left)",
                              padding,
                              ssh_buffer_get_len(session->in_buffer));
                goto error;
            }
            ssh_buffer_pass_bytes_end(session->in_buffer, padding);
            compsize = ssh_buffer_get_len(session->in_buffer);

#ifdef WITH_ZLIB
            if (session->current_crypto
                && session->current_crypto->do_compress_in
                && ssh_buffer_get_len(session->in_buffer) > 0) {
                rc = decompress_buffer(session, session->in_buffer,MAX_PACKET_LEN);
                if (rc < 0) {
                    goto error;
                }
            }
#endif /* WITH_ZLIB */
            payloadsize = ssh_buffer_get_len(session->in_buffer);
            session->recv_seq++;
            if (session->raw_counter != NULL) {
                session->raw_counter->in_bytes += payloadsize;
                session->raw_counter->in_packets++;
            }

            /*
             * We don't want to rewrite a new packet while still executing the
             * packet callbacks
             */
            session->packet_state = PACKET_STATE_PROCESSING;
            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, packet_len, padding, compsize, payloadsize);

            /* Execute callbacks */
            ssh_packet_process(session, session->in_packet.type);
            session->packet_state = PACKET_STATE_INIT;
            if (processed < receivedlen) {
                /* Handle a potential packet left in socket buffer */
                SSH_LOG(SSH_LOG_PACKET,
                        "Processing %" PRIdS " bytes left in socket buffer",
                        receivedlen-processed);

                ptr = ((uint8_t*)data) + processed;

                rc = ssh_packet_socket_callback(ptr, receivedlen - processed,user);
                processed += rc;
            }

            return processed;
        case PACKET_STATE_PROCESSING:
            SSH_LOG(SSH_LOG_PACKET, "Nested packet processing. Delaying.");
            return 0;
    }

    ssh_set_error(session,
                  SSH_FATAL,
                  "Invalid state into packet_read2(): %d",
                  session->packet_state);

error:
    session->session_state= SSH_SESSION_STATE_ERROR;
    SSH_LOG(SSH_LOG_PACKET,"Packet: processed %" PRIdS " bytes", processed);
    return processed;
}
Пример #2
0
/** @internal
 * @handles a data received event. It then calls the handlers for the different packet types
 * or and exception handler callback.
 * @param user pointer to current ssh_session
 * @param data pointer to the data received
 * @len length of data received. It might not be enough for a complete packet
 * @returns number of bytes read and processed.
 */
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};
    size_t current_macsize = 0;
    const uint8_t *packet;
    int to_be_read;
    int rc;
    uint32_t 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 (data == NULL) {
        goto error;
    }

    if (session->session_state == SSH_SESSION_STATE_ERROR) {
        goto error;
    }

    switch(session->packet_state) {
        case PACKET_STATE_INIT:
            if (receivedlen < blocksize) {
                /*
                 * We didn't receive enough data to read at least one
                 * block size, give up
                 */
                return 0;
            }

            memset(&session->in_packet, 0, sizeof(PACKET));

            if (session->in_buffer) {
                rc = ssh_buffer_reinit(session->in_buffer);
                if (rc < 0) {
                    goto error;
                }
            } else {
                session->in_buffer = ssh_buffer_new();
                if (session->in_buffer == NULL) {
                    goto error;
                }
            }

            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) {
                goto error;
            }

            if (len > MAX_PACKET_LEN) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "read_packet(): Packet len too high(%u %.4x)",
                              len, len);
                goto error;
            }

            to_be_read = len - blocksize + sizeof(uint32_t);
            if (to_be_read < 0) {
                /* remote sshd sends invalid sizes? */
                ssh_set_error(session,
                              SSH_FATAL,
                              "Given numbers of bytes left to be read < 0 (%d)!",
                              to_be_read);
                goto error;
            }

            /* Saves the status of the current operations */
            session->in_packet.len = len;
            session->packet_state = PACKET_STATE_SIZEREAD;
            /* FALL TROUGH */
        case PACKET_STATE_SIZEREAD:
            len = session->in_packet.len;
            to_be_read = len - blocksize + 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) {
                    /* give up, not enough data in buffer */
                    SSH_LOG(SSH_LOG_PACKET,"packet: partial packet (read len) [len=%d]",len);
                    return processed;
                }

                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;
            }

            if (session->current_crypto) {
                /*
                 * Decrypt the rest of the packet (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 (rc < 0) {
                        ssh_set_error(session, SSH_FATAL, "Decrypt error");
                        goto error;
                    }
                }

                /* copy the last part from the incoming buffer */
                packet = ((uint8_t *)data) + processed;
                memcpy(mac, packet, current_macsize);

                rc = ssh_packet_hmac_verify(session, session->in_buffer, mac, session->current_crypto->in_hmac);
                if (rc < 0) {
                    ssh_set_error(session, SSH_FATAL, "HMAC error");
                    goto error;
                }
                processed += current_macsize;
            }

            /* skip the size field which has been processed before */
            ssh_buffer_pass_bytes(session->in_buffer, sizeof(uint32_t));

            rc = ssh_buffer_get_u8(session->in_buffer, &padding);
            if (rc == 0) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "Packet too short to read padding");
                goto error;
            }

            if (padding > ssh_buffer_get_len(session->in_buffer)) {
                ssh_set_error(session,
                              SSH_FATAL,
                              "Invalid padding: %d (%d left)",
                              padding,
                              ssh_buffer_get_len(session->in_buffer));
                goto error;
            }
            ssh_buffer_pass_bytes_end(session->in_buffer, padding);
            compsize = ssh_buffer_get_len(session->in_buffer);

#ifdef WITH_ZLIB
            if (session->current_crypto
                && session->current_crypto->do_compress_in
                && ssh_buffer_get_len(session->in_buffer) > 0) {
                rc = decompress_buffer(session, session->in_buffer,MAX_PACKET_LEN);
                if (rc < 0) {
                    goto error;
                }
            }
#endif /* WITH_ZLIB */
            payloadsize = ssh_buffer_get_len(session->in_buffer);
            session->recv_seq++;
            if (session->raw_counter != NULL) {
                session->raw_counter->in_bytes += payloadsize;
                session->raw_counter->in_packets++;
            }

            /*
             * We don't want to rewrite a new packet while still executing the
             * packet callbacks
             */
            session->packet_state = PACKET_STATE_PROCESSING;
            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);

            /* Execute callbacks */
            ssh_packet_process(session, session->in_packet.type);
            session->packet_state = PACKET_STATE_INIT;
            if (processed < receivedlen) {
                /* Handle a potential packet left in socket buffer */
                SSH_LOG(SSH_LOG_PACKET,
                        "Processing %" PRIdS " bytes left in socket buffer",
                        receivedlen-processed);

                packet = ((uint8_t*)data) + processed;

                rc = ssh_packet_socket_callback(packet, receivedlen - processed,user);
                processed += rc;
            }

            return processed;
        case PACKET_STATE_PROCESSING:
            SSH_LOG(SSH_LOG_PACKET, "Nested packet processing. Delaying.");
            return 0;
    }

    ssh_set_error(session,
                  SSH_FATAL,
                  "Invalid state into packet_read2(): %d",
                  session->packet_state);

error:
    session->session_state= SSH_SESSION_STATE_ERROR;

    return processed;
}