1 files changed, 76 insertions, 0 deletions
diff --git a/ssh/censor1.c b/ssh/censor1.c
new file mode 100644
index 00000000..8dacd3a0
--- /dev/null
+++ b/ssh/censor1.c
@@ -0,0 +1,76 @@
+/*
+ * Packet-censoring code for SSH-1, used to identify sensitive fields
+ * like passwords so that the logging system can avoid writing them
+ * into log files.
+ */
+
+#include <assert.h>
+
+#include "putty.h"
+#include "ssh.h"
+
+int ssh1_censor_packet(
+    const PacketLogSettings *pls, int type, bool sender_is_client,
+    ptrlen pkt, logblank_t *blanks)
+{
+    int nblanks = 0;
+    ptrlen str;
+    BinarySource src[1];
+
+    BinarySource_BARE_INIT_PL(src, pkt);
+
+    if (pls->omit_data &&
+        (type == SSH1_SMSG_STDOUT_DATA ||
+         type == SSH1_SMSG_STDERR_DATA ||
+         type == SSH1_CMSG_STDIN_DATA ||
+         type == SSH1_MSG_CHANNEL_DATA)) {
+        /* "Session data" packets - omit the data string. */
+        if (type == SSH1_MSG_CHANNEL_DATA)
+            get_uint32(src);           /* skip channel id */
+        str = get_string(src);
+        if (!get_err(src)) {
+            assert(nblanks < MAX_BLANKS);
+            blanks[nblanks].offset = src->pos - str.len;
+            blanks[nblanks].type = PKTLOG_OMIT;
+            blanks[nblanks].len = str.len;
+            nblanks++;
+        }
+    }
+
+    if (sender_is_client && pls->omit_passwords) {
+        if (type == SSH1_CMSG_AUTH_PASSWORD ||
+            type == SSH1_CMSG_AUTH_TIS_RESPONSE ||
+            type == SSH1_CMSG_AUTH_CCARD_RESPONSE) {
+            /* If this is a password or similar packet, blank the
+             * password(s). */
+            assert(nblanks < MAX_BLANKS);
+            blanks[nblanks].offset = 0;
+            blanks[nblanks].len = pkt.len;
+            blanks[nblanks].type = PKTLOG_BLANK;
+            nblanks++;
+        } else if (type == SSH1_CMSG_X11_REQUEST_FORWARDING) {
+            /*
+             * If this is an X forwarding request packet, blank the
+             * fake auth data.
+             *
+             * Note that while we blank the X authentication data
+             * here, we don't take any special action to blank the
+             * start of an X11 channel, so using MIT-MAGIC-COOKIE-1
+             * and actually opening an X connection without having
+             * session blanking enabled is likely to leak your cookie
+             * into the log.
+             */
+            get_string(src);              /* skip protocol name */
+            str = get_string(src);
+            if (!get_err(src)) {
+                assert(nblanks < MAX_BLANKS);
+                blanks[nblanks].offset = src->pos - str.len;
+                blanks[nblanks].type = PKTLOG_BLANK;
+                blanks[nblanks].len = str.len;
+                nblanks++;
+            }
+        }
+    }
+
+    return nblanks;
+}