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New logging mode, which records the exact bytes sent over the wire

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in an SSH connection _in addition_ to the decrypted packets. This
will hopefully come in useful for debugging wire data corruption
issues: you can strace the server, enable this mode in the client,
and compare the sent and received data.

I'd _like_ to have this mode also log Diffie-Hellman private
exponents, session IDs, encryption and MAC keys, so that the
resulting log file could be used to independently verify the
correctness of all cryptographic operations performed by PuTTY.
However, I haven't been able to convince myself that the security
implications are acceptable. (It doesn't matter that this
information would permit an attacker to decrypt the session, because
the _already_ decrypted session is stored alongside it in the log
file. And I'm not planning, under any circumstances, to log users'
private keys. But gaining access to the log file while the session
was still running would permit an attacker to _hijack_ the session,
and that's the iffy bit.)

[originally from svn r6835]
This commit is contained in:
Simon Tatham
2006-08-29 19:07:11 +00:00
parent bb6482c35d
commit 8b11c26c57
4 changed files with 43 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
ssh.c
View File

@ -1442,11 +1442,17 @@ static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
return biglen + 4; /* len(length+padding+type+data+CRC) */
}
static int s_write(Ssh ssh, void *data, int len)
{
log_packet(ssh->logctx, PKT_OUTGOING, -1, NULL, data, len, 0, NULL);
return sk_write(ssh->s, (char *)data, len);
}
static void s_wrpkt(Ssh ssh, struct Packet *pkt)
{
int len, backlog, offset;
len = s_wrpkt_prepare(ssh, pkt, &offset);
backlog = sk_write(ssh->s, (char *)pkt->data + offset, len);
backlog = s_write(ssh, pkt->data + offset, len);
if (backlog > SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 1, backlog);
ssh_free_packet(pkt);
@ -1830,7 +1836,7 @@ static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
return;
}
len = ssh2_pkt_construct(ssh, pkt);
backlog = sk_write(ssh->s, (char *)pkt->data, len);
backlog = s_write(ssh, pkt->data, len);
if (backlog > SSH_MAX_BACKLOG)
ssh_throttle_all(ssh, 1, backlog);
@ -1928,8 +1934,7 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
static void ssh_pkt_defersend(Ssh ssh)
{
int backlog;
backlog = sk_write(ssh->s, (char *)ssh->deferred_send_data,
ssh->deferred_len);
backlog = s_write(ssh, ssh->deferred_send_data, ssh->deferred_len);
ssh->deferred_len = ssh->deferred_size = 0;
sfree(ssh->deferred_send_data);
ssh->deferred_send_data = NULL;
@ -2418,7 +2423,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
}
logeventf(ssh, "We claim version: %.*s",
strcspn(verstring, "\015\012"), verstring);
sk_write(ssh->s, verstring, strlen(verstring));
s_write(ssh, verstring, strlen(verstring));
sfree(verstring);
if (ssh->version == 2)
do_ssh2_transport(ssh, NULL, -1, NULL);
@ -2438,7 +2443,9 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
static void ssh_process_incoming_data(Ssh ssh,
unsigned char **data, int *datalen)
{
struct Packet *pktin = ssh->s_rdpkt(ssh, data, datalen);
struct Packet *pktin;
pktin = ssh->s_rdpkt(ssh, data, datalen);
if (pktin) {
ssh->protocol(ssh, NULL, 0, pktin);
ssh_free_packet(pktin);
@ -2481,6 +2488,9 @@ static void ssh_set_frozen(Ssh ssh, int frozen)
static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
{
/* Log raw data, if we're in that mode. */
log_packet(ssh->logctx, PKT_INCOMING, -1, NULL, data, datalen, 0, NULL);
crBegin(ssh->ssh_gotdata_crstate);
/*