Subversion Repositories Kolibri OS

;    sshlib_connection.inc - SSH connection

;

;    Copyright (C) 2016-2021 Jeffrey Amelynck

;

;    This program is free software: you can redistribute it and/or modify

;    it under the terms of the GNU General Public License as published by

;    the Free Software Foundation, either version 3 of the License, or

;    (at your option) any later version.

;

;    This program is distributed in the hope that it will be useful,

;    but WITHOUT ANY WARRANTY; without even the implied warranty of

;    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

;    GNU General Public License for more details.

;

;    You should have received a copy of the GNU General Public License

;    along with this program.  If not, see .

proc sshlib_connect con_ptr, hostname_sz

locals

        socketnum       dd ?

        sockaddr        sockaddr_in

        ctx_ptr         dd ?

endl

        mov     edi, [con_ptr]

        lea     eax, [edi + sshlib_connection.part_ex_hash_ctx]

        mov     [ctx_ptr], eax

; Set default values in sockaddr struct

        mov     [sockaddr.sin_family], AF_INET4

        mov     [sockaddr.sin_port], 22 shl 8

; Parse hostname_sz

; Verify length, extract port number if given and copy base url to sshlib_connection struct

; Port number, if provided, will be written in sockaddr struct.

; Hostname ends with any character equal to 0x20 or lower

        mov     esi, [hostname_sz]

        lea     edi, [edi + sshlib_connection.hostname_sz]

        mov     ecx, MAX_HOSTNAME_LENGTH

  @@:

        dec     ecx

        jz      .err_hostname

        lodsb

        cmp     al, ':'

        je      .do_port

        stosb

        cmp     al, 0x20

        ja      @r

        mov     byte[edi-1], 0

        jmp     .hostname_ok

  .do_port:

        xor     eax, eax

        xor     ebx, ebx

        mov     byte[edi-1], 0

  .portloop:

        lodsb

        cmp     al, 0x20

        jbe     .port_done

        sub     al, '0'

        jb      .err_hostname

        cmp     al, 9

        ja      .err_hostname

        lea     ebx, [ebx*4+ebx]

        shl     ebx, 1

        add     ebx, eax

        jmp     .portloop

  .port_done:

        xchg    bl, bh

        mov     [sockaddr.sin_port], bx

  .hostname_ok:

; resolve name

        push    esp     ; reserve stack place

        push    esp

        mov     eax, [con_ptr]

        lea     eax, [eax+sshlib_connection.hostname_sz]

        invoke  getaddrinfo, eax, 0, 0

        pop     esi

; test for error

        test    eax, eax

        jnz     .err_hostname

; convert IP address to decimal notation

        mov     eax, [esi+addrinfo.ai_addr]

        mov     eax, [eax+sockaddr_in.sin_addr]

        mov     [sockaddr.sin_addr], eax

        invoke  inet_ntoa, eax

; write result

        stdcall sshlib_callback_connecting, [con_ptr], eax

; free allocated memory

        invoke  freeaddrinfo, esi

; Create socket

        mcall   socket, AF_INET4, SOCK_STREAM, 0

        cmp     eax, -1

        jz      .err_sock

        mov     [socketnum], eax

        mov     ebx, [con_ptr]

        mov     [ebx + sshlib_connection.socketnum], eax

; Connect

        DEBUGF  2, "Connecting to server\n"

        lea     edx, [sockaddr]

        mcall   connect, [socketnum], , sizeof.sockaddr_in

        test    eax, eax

        jnz     .err_sock

; Start calculating hash

        invoke  sha2_256_init, [ctx_ptr]

; HASH: string  V_C, the client's version string (CR and NL excluded)

        invoke  sha2_256_update, [ctx_ptr], ssh_ident_ha, ssh_msg_ident.length+4-2

; >> Send our identification string

        DEBUGF  2, "Sending ID string\n"

        mcall   send, [socketnum], ssh_msg_ident, ssh_msg_ident.length, 0

        cmp     eax, -1

        je      .err_sock

; << Check protocol version of server

        mov     edx, [con_ptr]

        lea     edx, [edx + sshlib_connection.rx_buffer + 4]

        mcall   recv, [socketnum], , PACKETSIZE, 0

        cmp     eax, -1

        je      .err_sock

        DEBUGF  2, "Received ID string\n"

        cmp     dword[edx], "SSH-"

        jne     .err_proto

        cmp     dword[edx+4], "2.0-"

        jne     .err_proto

; HASH: string  V_S, the server's version string (CR and NL excluded)

        lea     ecx, [eax+2]

        sub     eax, 2

        bswap   eax

        sub     edx, 4

        mov     dword[edx], eax

        invoke  sha2_256_update, [ctx_ptr], edx, ecx

; >> Key Exchange init

        mov     eax, [con_ptr]

        mov     [eax + sshlib_connection.status], SSHLIB_CON_STAT_INIT

        mov     [eax + sshlib_connection.algo_kex], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_hostkey], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_crypt_rx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_crypt_tx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_mac_rx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_mac_tx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_compr_rx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.algo_compr_tx], SSHLIB_ALGO_NONE

        mov     [eax + sshlib_connection.rx_mac_seqnr], 0

        mov     [eax + sshlib_connection.tx_mac_seqnr], 0

        mov     [eax + sshlib_connection.rx_crypt_blocksize], 4             ; minimum blocksize

        mov     [eax + sshlib_connection.tx_crypt_blocksize], 4

        mov     [eax + sshlib_connection.rx_crypt_proc], sshlib_crypt_null

        mov     [eax + sshlib_connection.tx_crypt_proc], sshlib_crypt_null

        mov     [eax + sshlib_connection.rx_mac_proc], 0

        mov     [eax + sshlib_connection.tx_mac_proc], 0

        mov     [eax + sshlib_connection.rx_mac_length], 0

        mov     [eax + sshlib_connection.tx_mac_length], 0

        mov     [eax + sshlib_connection.tx_pad_size], 8

        mov     [eax + sshlib_connection.tx_pad_proc], sshlib_padd_null

        DEBUGF  2, "Sending KEX init\n"

        mov     edi, ssh_msg_kex.cookie

        call    MBRandom

        stosd

        call    MBRandom

        stosd

        call    MBRandom

        stosd

        call    MBRandom

        stosd

        stdcall sshlib_send_packet, [con_ptr], ssh_msg_kex, ssh_msg_kex.length, 0

        cmp     eax, -1

        je      .err_sock

; HASH: string  I_C, the payload of the client's SSH_MSG_KEXINIT

        mov     esi, [con_ptr]

        mov     eax, [esi+sshlib_connection.tx_buffer.packet_length]

        bswap   eax

        movzx   ebx, [esi+sshlib_connection.tx_buffer.padding_length]

        sub     eax, ebx

        dec     eax

        lea     edx, [eax+4]

        bswap   eax

        lea     esi, [esi+sshlib_connection.tx_buffer+1]

        mov     dword[esi], eax

        invoke  sha2_256_update, [ctx_ptr], esi, edx

; << Check key exchange init of server

        stdcall sshlib_recv_packet, [con_ptr], 0

        cmp     eax, -1

        je      .err_sock

        mov     esi, [con_ptr]

        cmp     [esi + sshlib_connection.rx_buffer.message_code], SSH_MSG_KEXINIT

        jne     .err_proto

        DEBUGF  2, "Received KEX init\n"

        lea     esi, [esi + sshlib_connection.rx_buffer + sizeof.ssh_packet_header + 16]

        lodsd

        bswap   eax

        DEBUGF  1, "kex_algorithms: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "server_host_key_algorithms: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "encryption_algorithms_client_to_server: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "encryption_algorithms_server_to_client: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "mac_algorithms_client_to_server: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "mac_algorithms_server_to_client: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "compression_algorithms_client_to_server: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "compression_algorithms_server_to_client: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "languages_client_to_server: %s\n", esi

        add     esi, eax

        lodsd

        bswap   eax

        DEBUGF  1, "languages_server_to_client: %s\n", esi

        add     esi, eax

        lodsb

        DEBUGF  1, "KEX First Packet Follows: %u\n", al

; TODO: parse this structure and set algorithm codes accordingly

; FIXME: hardcoded for now

        mov     esi, [con_ptr]

        mov     [esi+sshlib_connection.algo_kex], SSHLIB_KEX_DH_SHA256

        mov     [esi+sshlib_connection.algo_hostkey], SSHLIB_HOSTKEY_RSA

        mov     [esi+sshlib_connection.algo_crypt_rx], SSHLIB_CRYPT_AES256_CTR

        mov     [esi+sshlib_connection.algo_crypt_tx], SSHLIB_CRYPT_AES256_CTR

        mov     [esi+sshlib_connection.algo_mac_rx], SSHLIB_HMAC_SHA2_256

        mov     [esi+sshlib_connection.algo_mac_tx], SSHLIB_HMAC_SHA2_256

        mov     [esi+sshlib_connection.algo_compr_rx], SSHLIB_COMPR_NONE

        mov     [esi+sshlib_connection.algo_compr_tx], SSHLIB_COMPR_NONE

; HASH: string I_S, the payload of the servers's SSH_MSG_KEXINIT

        mov     esi, [con_ptr]

        mov     eax, [esi+sshlib_connection.rx_buffer.packet_length]

        movzx   ebx, [esi+sshlib_connection.rx_buffer.padding_length]

        sub     eax, ebx

        dec     eax

        lea     edx, [eax+4]

        bswap   eax

        lea     esi, [esi+sshlib_connection.rx_buffer+1]

        mov     dword[esi], eax

        invoke  sha2_256_update, [ctx_ptr], esi, edx

; Exchange keys with the server

        stdcall sshlib_dh_gex, [con_ptr]

        test    eax, eax

        jnz     .err

; Re-seed RNG for padding bytes

        call    create_seed

        call    init_random

        xor     eax, eax

        ret

  .err_hostname:

        mov     eax, SSHLIB_ERR_HOSTNAME

        ret

  .err_sock:

        mov     eax, SSHLIB_ERR_SOCKET

        ret

  .err_proto:

        mov     eax, SSHLIB_ERR_PROTOCOL

        ret

  .err:

        ret

endp

; Handle common messages and return to caller for specific ones

proc sshlib_msg_handler, con_ptr, flags

  .recv:

; Send a window update if advertised window drops below half

        cmp     [ssh_chan.rcv_wnd], BUFFERSIZE/2

        ja      .no_wnd

        mov     eax, BUFFERSIZE

        bswap   eax

        mov     [ssh_msg_channel_window_adjust.wnd], eax

        stdcall sshlib_send_packet, [con_ptr], ssh_msg_channel_window_adjust, ssh_msg_channel_window_adjust.length, 0

        mov     [ssh_chan.rcv_wnd], BUFFERSIZE

  .no_wnd:

; Receive 1 SSH packet

        stdcall sshlib_recv_packet, [con_ptr], [flags]

        cmp     eax, 0

        jle     .ret

        mov     esi, [con_ptr]

        lea     esi, [esi + sshlib_connection.rx_buffer]

        mov     al, [esi + ssh_packet_header.message_code]

        inc     esi

        cmp     al, SSH_MSG_DISCONNECT

        je      .disc

        cmp     al, SSH_MSG_IGNORE

        je      .ign

        cmp     al, SSH_MSG_DEBUG

        je      .dbg

        cmp     al, SSH_MSG_GLOBAL_REQUEST

        je      .glob_req

        cmp     al, SSH_MSG_CHANNEL_WINDOW_ADJUST

        je      .chan_win_adj

;        cmp     al, SSH_MSG_CHANNEL_REQUEST

;        je      .chan_req

        cmp     al, SSH_MSG_CHANNEL_EOF

        je      .chan_eof

        cmp     al, SSH_MSG_CHANNEL_CLOSE

        je      .chan_close

  .ret:

        ret

  .disc:

        DEBUGF  3, "SSH: Disconnect message received\n"

        mov     eax, SSHLIB_ERR_DISCONNECTING

        ret

  .ign:

        DEBUGF  3, "SSH: Ignore MSG received\n"

        jmp     .recv

  .dbg:

        DEBUGF  3, "SSH: Debug MSG received\n"

        ;TODO

        jmp     .recv

  .glob_req:

        DEBUGF  3, "SSH: Global MSG received\n"

        ;TODO

        jmp     .recv

  .chan_win_adj:

        mov     eax, dword[esi]

        bswap   eax

        mov     [ssh_chan.snd_wnd], eax

        ; TODO: validate channel number, act accordingly

        DEBUGF  3, "SSH: Channel %u window update received\n", eax

        jmp     .recv

  .chan_eof:

        mov     eax, dword[esi]

        bswap   eax

        ; TODO: validate channel number, act accordingly

        DEBUGF  3, "SSH: Channel %u EOF received\n", eax

        jmp     .recv

  .chan_close:

        mov     eax, dword[esi]

        bswap   eax

        ; TODO: validate channel number

        DEBUGF  3, "SSH: Channel %u close received\n", eax

        ; Reply with close message

        stdcall sshlib_send_packet, [con_ptr], ssh_msg_channel_close, ssh_msg_channel_close.length, 0

        xor     eax, eax

        ret

endp