src/TortoisePlink/ssh/censor2.c

   1 /*
   2  * Packet-censoring code for SSH-2, used to identify sensitive fields
   3  * like passwords so that the logging system can avoid writing them
   4  * into log files.
   5  */
   6
   7 #include <assert.h>
   8
   9 #include "putty.h"
  10 #include "ssh.h"
  11
  12 int ssh2_censor_packet(
  13     const PacketLogSettings *pls, int type, bool sender_is_client,
  14     ptrlen pkt, logblank_t *blanks)
  15 {
  16     int nblanks = 0;
  17     ptrlen str;
  18     BinarySource src[1];
  19
  20     BinarySource_BARE_INIT_PL(src, pkt);
  21
  22     if (pls->omit_data &&
  23         (type == SSH2_MSG_CHANNEL_DATA ||
  24          type == SSH2_MSG_CHANNEL_EXTENDED_DATA)) {
  25         /* "Session data" packets - omit the data string. */
  26         get_uint32(src);              /* skip channel id */
  27         if (type == SSH2_MSG_CHANNEL_EXTENDED_DATA)
  28             get_uint32(src);          /* skip extended data type */
  29         str = get_string(src);
  30         if (!get_err(src)) {
  31             assert(nblanks < MAX_BLANKS);
  32             blanks[nblanks].offset = src->pos - str.len;
  33             blanks[nblanks].type = PKTLOG_OMIT;
  34             blanks[nblanks].len = str.len;
  35             nblanks++;
  36         }
  37     }
  38
  39     if (sender_is_client && pls->omit_passwords) {
  40         if (type == SSH2_MSG_USERAUTH_REQUEST) {
  41             /* If this is a password packet, blank the password(s). */
  42             get_string(src);              /* username */
  43             get_string(src);              /* service name */
  44             str = get_string(src);        /* auth method */
  45             if (ptrlen_eq_string(str, "password")) {
  46                 get_bool(src);
  47                 /* Blank the password field. */
  48                 str = get_string(src);
  49                 if (!get_err(src)) {
  50                     assert(nblanks < MAX_BLANKS);
  51                     blanks[nblanks].offset = src->pos - str.len;
  52                     blanks[nblanks].type = PKTLOG_BLANK;
  53                     blanks[nblanks].len = str.len;
  54                     nblanks++;
  55                     /* If there's another password field beyond it
  56                      * (change of password), blank that too. */
  57                     str = get_string(src);
  58                     if (!get_err(src))
  59                         blanks[nblanks-1].len =
  60                             src->pos - blanks[nblanks].offset;
  61                 }
  62             }
  63         } else if (pls->actx == SSH2_PKTCTX_KBDINTER &&
  64                    type == SSH2_MSG_USERAUTH_INFO_RESPONSE) {
  65             /* If this is a keyboard-interactive response packet,
  66              * blank the responses. */
  67             get_uint32(src);
  68             assert(nblanks < MAX_BLANKS);
  69             blanks[nblanks].offset = src->pos;
  70             blanks[nblanks].type = PKTLOG_BLANK;
  71             do {
  72                 str = get_string(src);
  73             } while (!get_err(src));
  74             blanks[nblanks].len = src->pos - blanks[nblanks].offset;
  75             nblanks++;
  76         } else if (type == SSH2_MSG_CHANNEL_REQUEST) {
  77             /*
  78              * If this is an X forwarding request packet, blank the
  79              * fake auth data.
  80              *
  81              * Note that while we blank the X authentication data
  82              * here, we don't take any special action to blank the
  83              * start of an X11 channel, so using MIT-MAGIC-COOKIE-1
  84              * and actually opening an X connection without having
  85              * session blanking enabled is likely to leak your cookie
  86              * into the log.
  87              */
  88             get_uint32(src);
  89             str = get_string(src);
  90             if (ptrlen_eq_string(str, "x11-req")) {
  91                 get_bool(src);
  92                 get_bool(src);
  93                 get_string(src);
  94                 str = get_string(src);
  95                 if (!get_err(src)) {
  96                     assert(nblanks < MAX_BLANKS);
  97                     blanks[nblanks].offset = src->pos - str.len;
  98                     blanks[nblanks].type = PKTLOG_BLANK;
  99                     blanks[nblanks].len = str.len;
 100                     nblanks++;
 101                 }
 102             }
 103         }
 104     }
 105
 106     return nblanks;
 107 }