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Diff for /src/usr.bin/ssh/packet.c between version 1.38.2.4 and 1.38.2.5

version 1.38.2.4, 2001/05/07 21:09:31 version 1.38.2.5, 2001/09/27 00:15:42
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  *   *
  *   *
  * SSH2 packet format added by Markus Friedl.   * SSH2 packet format added by Markus Friedl.
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.   * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  *   *
  * Redistribution and use in source and binary forms, with or without   * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions   * modification, are permitted provided that the following conditions
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 static int connection_in = -1;  static int connection_in = -1;
 static int connection_out = -1;  static int connection_out = -1;
   
 /*  
  * Cipher type.  This value is only used to determine whether to pad the  
  * packets with zeroes or random data.  
  */  
 static int cipher_type = SSH_CIPHER_NONE;  
   
 /* Protocol flags for the remote side. */  /* Protocol flags for the remote side. */
 static u_int remote_protocol_flags = 0;  static u_int remote_protocol_flags = 0;
   
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 /* Set to true if the connection is interactive. */  /* Set to true if the connection is interactive. */
 static int interactive_mode = 0;  static int interactive_mode = 0;
   
 /* True if SSH2 packet format is used */  
 int use_ssh2_packet_format = 0;  
   
 /* Session key information for Encryption and MAC */  /* Session key information for Encryption and MAC */
 Newkeys *newkeys[MODE_MAX];  Newkeys *newkeys[MODE_MAX];
   
 void  
 packet_set_ssh2_format(void)  
 {  
         DBG(debug("use_ssh2_packet_format"));  
         use_ssh2_packet_format = 1;  
         newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;  
 }  
   
 /*  /*
  * Sets the descriptors used for communication.  Disables encryption until   * Sets the descriptors used for communication.  Disables encryption until
  * packet_set_encryption_key is called.   * packet_set_encryption_key is called.
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                 fatal("packet_set_connection: cannot load cipher 'none'");                  fatal("packet_set_connection: cannot load cipher 'none'");
         connection_in = fd_in;          connection_in = fd_in;
         connection_out = fd_out;          connection_out = fd_out;
         cipher_type = SSH_CIPHER_NONE;  
         cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0);          cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0);
         cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0);          cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0);
           newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
         if (!initialized) {          if (!initialized) {
                 initialized = 1;                  initialized = 1;
                 buffer_init(&input);                  buffer_init(&input);
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 packet_set_protocol_flags(u_int protocol_flags)  packet_set_protocol_flags(u_int protocol_flags)
 {  {
         remote_protocol_flags = protocol_flags;          remote_protocol_flags = protocol_flags;
         channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0);  
 }  }
   
 /* Returns the remote protocol flags set earlier by the above function. */  /* Returns the remote protocol flags set earlier by the above function. */
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  * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.   * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
  */   */
   
 void  static void
 packet_init_compression()  packet_init_compression(void)
 {  {
         if (compression_buffer_ready == 1)          if (compression_buffer_ready == 1)
                 return;                  return;
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 void  void
 packet_start_compression(int level)  packet_start_compression(int level)
 {  {
         if (packet_compression && !use_ssh2_packet_format)          if (packet_compression && !compat20)
                 fatal("Compression already enabled.");                  fatal("Compression already enabled.");
         packet_compression = 1;          packet_compression = 1;
         packet_init_compression();          packet_init_compression();
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 }  }
   
 /*  /*
  * Encrypts the given number of bytes, copying from src to dest. bytes is  
  * known to be a multiple of 8.  
  */  
   
 void  
 packet_encrypt(CipherContext * cc, void *dest, void *src,  
     u_int bytes)  
 {  
         cipher_encrypt(cc, dest, src, bytes);  
 }  
   
 /*  
  * Decrypts the given number of bytes, copying from src to dest. bytes is  
  * known to be a multiple of 8.  
  */  
   
 void  
 packet_decrypt(CipherContext *context, void *dest, void *src, u_int bytes)  
 {  
         /*  
          * Cryptographic attack detector for ssh - Modifications for packet.c  
          * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com)  
          */  
         if (!compat20 &&  
             context->cipher->number != SSH_CIPHER_NONE &&  
             detect_attack(src, bytes, NULL) == DEATTACK_DETECTED)  
                 packet_disconnect("crc32 compensation attack: network attack detected");  
   
         cipher_decrypt(context, dest, src, bytes);  
 }  
   
 /*  
  * Causes any further packets to be encrypted using the given key.  The same   * Causes any further packets to be encrypted using the given key.  The same
  * key is used for both sending and reception.  However, both directions are   * key is used for both sending and reception.  However, both directions are
  * encrypted independently of each other.   * encrypted independently of each other.
  */   */
   
 void  void
 packet_set_encryption_key(const u_char *key, u_int keylen,  packet_set_encryption_key(const u_char *key, u_int keylen,
     int number)      int number)
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         cipher_init(&send_context, cipher, key, keylen, NULL, 0);          cipher_init(&send_context, cipher, key, keylen, NULL, 0);
 }  }
   
 /* Starts constructing a packet to send. */  /* Start constructing a packet to send. */
   
 void  void
 packet_start1(int type)  packet_start(u_char type)
 {  {
         char buf[9];          u_char buf[9];
           int len;
   
           DBG(debug("packet_start[%d]", type));
           len = compat20 ? 6 : 9;
           memset(buf, 0, len - 1);
           buf[len - 1] = type;
         buffer_clear(&outgoing_packet);          buffer_clear(&outgoing_packet);
         memset(buf, 0, 8);          buffer_append(&outgoing_packet, buf, len);
         buf[8] = type;  
         buffer_append(&outgoing_packet, buf, 9);  
 }  }
   
   /* Append payload. */
 void  void
 packet_start2(int type)  
 {  
         char buf[4+1+1];  
   
         buffer_clear(&outgoing_packet);  
         memset(buf, 0, sizeof buf);  
         /* buf[0..3] = payload_len; */  
         /* buf[4] =    pad_len; */  
         buf[5] = type & 0xff;  
         buffer_append(&outgoing_packet, buf, sizeof buf);  
 }  
   
 void  
 packet_start(int type)  
 {  
         DBG(debug("packet_start[%d]", type));  
         if (use_ssh2_packet_format)  
                 packet_start2(type);  
         else  
                 packet_start1(type);  
 }  
   
 /* Appends a character to the packet data. */  
   
 void  
 packet_put_char(int value)  packet_put_char(int value)
 {  {
         char ch = value;          char ch = value;
         buffer_append(&outgoing_packet, &ch, 1);          buffer_append(&outgoing_packet, &ch, 1);
 }  }
   
 /* Appends an integer to the packet data. */  
   
 void  void
 packet_put_int(u_int value)  packet_put_int(u_int value)
 {  {
         buffer_put_int(&outgoing_packet, value);          buffer_put_int(&outgoing_packet, value);
 }  }
   
 /* Appends a string to packet data. */  
   
 void  void
 packet_put_string(const char *buf, u_int len)  packet_put_string(const char *buf, u_int len)
 {  {
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 void  void
 packet_put_cstring(const char *str)  packet_put_cstring(const char *str)
 {  {
         buffer_put_string(&outgoing_packet, str, strlen(str));          buffer_put_cstring(&outgoing_packet, str);
 }  }
   
 void  void
 packet_put_raw(const char *buf, u_int len)  packet_put_raw(const char *buf, u_int len)
 {  {
         buffer_append(&outgoing_packet, buf, len);          buffer_append(&outgoing_packet, buf, len);
 }  }
   
   
 /* Appends an arbitrary precision integer to packet data. */  
   
 void  void
 packet_put_bignum(BIGNUM * value)  packet_put_bignum(BIGNUM * value)
 {  {
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  * encrypts the packet before sending.   * encrypts the packet before sending.
  */   */
   
 void  static void
 packet_send1(void)  packet_send1(void)
 {  {
         char buf[8], *cp;          char buf[8], *cp;
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         /* Insert padding. Initialized to zero in packet_start1() */          /* Insert padding. Initialized to zero in packet_start1() */
         padding = 8 - len % 8;          padding = 8 - len % 8;
         if (cipher_type != SSH_CIPHER_NONE) {          if (send_context.cipher->number != SSH_CIPHER_NONE) {
                 cp = buffer_ptr(&outgoing_packet);                  cp = buffer_ptr(&outgoing_packet);
                 for (i = 0; i < padding; i++) {                  for (i = 0; i < padding; i++) {
                         if (i % 4 == 0)                          if (i % 4 == 0)
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         PUT_32BIT(buf, len);          PUT_32BIT(buf, len);
         buffer_append(&output, buf, 4);          buffer_append(&output, buf, 4);
         buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));          buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
         packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),          cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
                        buffer_len(&outgoing_packet));                         buffer_len(&outgoing_packet));
   
 #ifdef PACKET_DEBUG  #ifdef PACKET_DEBUG
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          */           */
 }  }
   
 void  static void
 set_newkeys(int mode)  set_newkeys(int mode)
 {  {
         Enc *enc;          Enc *enc;
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 /*  /*
  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)   * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
  */   */
 void  static void
 packet_send2(void)  packet_send2(void)
 {  {
         static u_int32_t seqnr = 0;          static u_int32_t seqnr = 0;
         u_char *macbuf = NULL;          u_char type, *ucp, *macbuf = NULL;
         char *cp;          char *cp;
         u_int packet_length = 0;          u_int packet_length = 0;
         u_int i, padlen, len;          u_int i, padlen, len;
         u_int32_t rand = 0;          u_int32_t rand = 0;
         int type;  
         Enc *enc   = NULL;          Enc *enc   = NULL;
         Mac *mac   = NULL;          Mac *mac   = NULL;
         Comp *comp = NULL;          Comp *comp = NULL;
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         }          }
         block_size = enc ? enc->cipher->block_size : 8;          block_size = enc ? enc->cipher->block_size : 8;
   
         cp = buffer_ptr(&outgoing_packet);          ucp = (u_char *) buffer_ptr(&outgoing_packet);
         type = cp[5] & 0xff;          type = ucp[5];
   
 #ifdef PACKET_DEBUG  #ifdef PACKET_DEBUG
         fprintf(stderr, "plain:     ");          fprintf(stderr, "plain:     ");
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         }          }
         /* packet_length includes payload, padding and padding length field */          /* packet_length includes payload, padding and padding length field */
         packet_length = buffer_len(&outgoing_packet) - 4;          packet_length = buffer_len(&outgoing_packet) - 4;
         cp = buffer_ptr(&outgoing_packet);          ucp = (u_char *)buffer_ptr(&outgoing_packet);
         PUT_32BIT(cp, packet_length);          PUT_32BIT(ucp, packet_length);
         cp[4] = padlen & 0xff;          ucp[4] = padlen;
         DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));          DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
   
         /* compute MAC over seqnr and packet(length fields, payload, padding) */          /* compute MAC over seqnr and packet(length fields, payload, padding) */
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         }          }
         /* encrypt packet and append to output buffer. */          /* encrypt packet and append to output buffer. */
         buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));          buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
         packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),          cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
             buffer_len(&outgoing_packet));              buffer_len(&outgoing_packet));
         /* append unencrypted MAC */          /* append unencrypted MAC */
         if (mac && mac->enabled)          if (mac && mac->enabled)
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 void  void
 packet_send()  packet_send()
 {  {
         if (use_ssh2_packet_format)          if (compat20)
                 packet_send2();                  packet_send2();
         else          else
                 packet_send1();                  packet_send1();
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         for (;;) {          for (;;) {
                 /* Try to read a packet from the buffer. */                  /* Try to read a packet from the buffer. */
                 type = packet_read_poll(payload_len_ptr);                  type = packet_read_poll(payload_len_ptr);
                 if (!use_ssh2_packet_format && (                  if (!compat20 && (
                     type == SSH_SMSG_SUCCESS                      type == SSH_SMSG_SUCCESS
                     || type == SSH_SMSG_FAILURE                      || type == SSH_SMSG_FAILURE
                     || type == SSH_CMSG_EOF                      || type == SSH_CMSG_EOF
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  *      Check bytes   *      Check bytes
  */   */
   
 int  static int
 packet_read_poll1(int *payload_len_ptr)  packet_read_poll1(int *payload_len_ptr)
 {  {
         u_int len, padded_len;          u_int len, padded_len;
         u_char *ucp;          u_char *ucp, type;
         char buf[8], *cp;          char *cp;
         u_int checksum, stored_checksum;          u_int checksum, stored_checksum;
   
         /* Check if input size is less than minimum packet size. */          /* Check if input size is less than minimum packet size. */
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         /* Consume packet length. */          /* Consume packet length. */
         buffer_consume(&input, 4);          buffer_consume(&input, 4);
   
         /* Copy data to incoming_packet. */          /*
            * Cryptographic attack detector for ssh
            * (C)1998 CORE-SDI, Buenos Aires Argentina
            * Ariel Futoransky(futo@core-sdi.com)
            */
           if (receive_context.cipher->number != SSH_CIPHER_NONE &&
               detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED)
                   packet_disconnect("crc32 compensation attack: network attack detected");
   
           /* Decrypt data to incoming_packet. */
         buffer_clear(&incoming_packet);          buffer_clear(&incoming_packet);
         buffer_append_space(&incoming_packet, &cp, padded_len);          buffer_append_space(&incoming_packet, &cp, padded_len);
         packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);          cipher_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
   
         buffer_consume(&input, padded_len);          buffer_consume(&input, padded_len);
   
 #ifdef PACKET_DEBUG  #ifdef PACKET_DEBUG
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         buffer_consume(&incoming_packet, 8 - len % 8);          buffer_consume(&incoming_packet, 8 - len % 8);
   
         /* Test check bytes. */          /* Test check bytes. */
   
         if (len != buffer_len(&incoming_packet))          if (len != buffer_len(&incoming_packet))
                 packet_disconnect("packet_read_poll: len %d != buffer_len %d.",                  packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
                     len, buffer_len(&incoming_packet));                      len, buffer_len(&incoming_packet));
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                 packet_disconnect("Corrupted check bytes on input.");                  packet_disconnect("Corrupted check bytes on input.");
         buffer_consume_end(&incoming_packet, 4);          buffer_consume_end(&incoming_packet, 4);
   
         /* If using packet compression, decompress the packet. */  
         if (packet_compression) {          if (packet_compression) {
                 buffer_clear(&compression_buffer);                  buffer_clear(&compression_buffer);
                 buffer_uncompress(&incoming_packet, &compression_buffer);                  buffer_uncompress(&incoming_packet, &compression_buffer);
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                 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),                  buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
                     buffer_len(&compression_buffer));                      buffer_len(&compression_buffer));
         }          }
         /* Get packet type. */          type = buffer_get_char(&incoming_packet);
         buffer_get(&incoming_packet, &buf[0], 1);  
   
         /* Return length of payload (without type field). */  
         *payload_len_ptr = buffer_len(&incoming_packet);          *payload_len_ptr = buffer_len(&incoming_packet);
           return type;
         /* Return type. */  
         return (u_char) buf[0];  
 }  }
   
 int  static int
 packet_read_poll2(int *payload_len_ptr)  packet_read_poll2(int *payload_len_ptr)
 {  {
         static u_int32_t seqnr = 0;          static u_int32_t seqnr = 0;
         static u_int packet_length = 0;          static u_int packet_length = 0;
         u_int padlen, need;          u_int padlen, need;
         u_char buf[8], *macbuf;          u_char *macbuf, *ucp, type;
         u_char *ucp;  
         char *cp;          char *cp;
         int type;  
         int maclen, block_size;          int maclen, block_size;
         Enc *enc   = NULL;          Enc *enc   = NULL;
         Mac *mac   = NULL;          Mac *mac   = NULL;
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                         return SSH_MSG_NONE;                          return SSH_MSG_NONE;
                 buffer_clear(&incoming_packet);                  buffer_clear(&incoming_packet);
                 buffer_append_space(&incoming_packet, &cp, block_size);                  buffer_append_space(&incoming_packet, &cp, block_size);
                 packet_decrypt(&receive_context, cp, buffer_ptr(&input),                  cipher_decrypt(&receive_context, cp, buffer_ptr(&input),
                     block_size);                      block_size);
                 ucp = (u_char *) buffer_ptr(&incoming_packet);                  ucp = (u_char *) buffer_ptr(&incoming_packet);
                 packet_length = GET_32BIT(ucp);                  packet_length = GET_32BIT(ucp);
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         buffer_dump(&input);          buffer_dump(&input);
 #endif  #endif
         buffer_append_space(&incoming_packet, &cp, need);          buffer_append_space(&incoming_packet, &cp, need);
         packet_decrypt(&receive_context, cp, buffer_ptr(&input), need);          cipher_decrypt(&receive_context, cp, buffer_ptr(&input), need);
         buffer_consume(&input, need);          buffer_consume(&input, need);
         /*          /*
          * compute MAC over seqnr and packet,           * compute MAC over seqnr and packet,
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         /* get padlen */          /* get padlen */
         cp = buffer_ptr(&incoming_packet) + 4;          cp = buffer_ptr(&incoming_packet) + 4;
         padlen = *cp & 0xff;          padlen = (u_char) *cp;
         DBG(debug("input: padlen %d", padlen));          DBG(debug("input: padlen %d", padlen));
         if (padlen < 4)          if (padlen < 4)
                 packet_disconnect("Corrupted padlen %d on input.", padlen);                  packet_disconnect("Corrupted padlen %d on input.", padlen);
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          * get packet type, implies consume.           * get packet type, implies consume.
          * return length of payload (without type field)           * return length of payload (without type field)
          */           */
         buffer_get(&incoming_packet, (char *)&buf[0], 1);          type = buffer_get_char(&incoming_packet);
         *payload_len_ptr = buffer_len(&incoming_packet);  
   
         /* reset for next packet */  
         packet_length = 0;  
   
         /* extract packet type */  
         type = (u_char)buf[0];  
   
         if (type == SSH2_MSG_NEWKEYS)          if (type == SSH2_MSG_NEWKEYS)
                 set_newkeys(MODE_IN);                  set_newkeys(MODE_IN);
           *payload_len_ptr = buffer_len(&incoming_packet);
 #ifdef PACKET_DEBUG  #ifdef PACKET_DEBUG
         fprintf(stderr, "read/plain[%d]:\r\n", type);          fprintf(stderr, "read/plain[%d]:\r\n", type);
         buffer_dump(&incoming_packet);          buffer_dump(&incoming_packet);
 #endif  #endif
         return (u_char)type;          /* reset for next packet */
           packet_length = 0;
           return type;
 }  }
   
 int  int
 packet_read_poll(int *payload_len_ptr)  packet_read_poll(int *payload_len_ptr)
 {  {
           int reason;
           u_char type;
         char *msg;          char *msg;
         for (;;) {  
                 int type = use_ssh2_packet_format ?  
                     packet_read_poll2(payload_len_ptr):  
                     packet_read_poll1(payload_len_ptr);  
   
                 if(compat20) {          for (;;) {
                         int reason;                  if (compat20) {
                         if (type != 0)                          type = packet_read_poll2(payload_len_ptr);
                           if (type)
                                 DBG(debug("received packet type %d", type));                                  DBG(debug("received packet type %d", type));
                         switch(type) {                          switch(type) {
                         case SSH2_MSG_IGNORE:                          case SSH2_MSG_IGNORE:
Line 1002 
Line 911 
                                 break;                                  break;
                         }                          }
                 } else {                  } else {
                           type = packet_read_poll1(payload_len_ptr);
                         switch(type) {                          switch(type) {
                         case SSH_MSG_IGNORE:                          case SSH_MSG_IGNORE:
                                 break;                                  break;
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                                 xfree(msg);                                  xfree(msg);
                                 break;                                  break;
                         default:                          default:
                                 if (type != 0)                                  if (type)
                                         DBG(debug("received packet type %d", type));                                          DBG(debug("received packet type %d", type));
                                 return type;                                  return type;
                                 break;                                  break;
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                 packet_put_cstring("");                  packet_put_cstring("");
         } else {          } else {
                 packet_start(SSH_MSG_DISCONNECT);                  packet_start(SSH_MSG_DISCONNECT);
                 packet_put_string(buf, strlen(buf));                  packet_put_cstring(buf);
         }          }
         packet_send();          packet_send();
         packet_write_wait();          packet_write_wait();
   
         /* Stop listening for connections. */          /* Stop listening for connections. */
         channel_stop_listening();          channel_close_all();
   
         /* Close the connection. */          /* Close the connection. */
         packet_close();          packet_close();
Line 1316 
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                 log("packet_set_maxsize: bad size %d", s);                  log("packet_set_maxsize: bad size %d", s);
                 return -1;                  return -1;
         }          }
         log("packet_set_maxsize: setting to %d", s);          debug("packet_set_maxsize: setting to %d", s);
         max_packet_size = s;          max_packet_size = s;
         return s;          return s;
 }  }
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         int blocksize, padlen, have, need, nb, mini, nbytes;          int blocksize, padlen, have, need, nb, mini, nbytes;
         Enc *enc = NULL;          Enc *enc = NULL;
   
         if (use_ssh2_packet_format == 0)          if (compat20 == 0)
                 return;                  return;
   
         have = buffer_len(&outgoing_packet);          have = buffer_len(&outgoing_packet);
Legend:
Removed from v.1.38.2.4  
changed lines
  Added in v.1.38.2.5