upstream commit
Revise hostkeys@openssh.com hostkey learning extension.
The client will not ask the server to prove ownership of the private
halves of any hitherto-unseen hostkeys it offers to the client.
Allow UpdateHostKeys option to take an 'ask' argument to let the
user manually review keys offered.
ok markus@
diff --git a/serverloop.c b/serverloop.c
index 48bb3f6..5633ceb 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.176 2015/01/20 23:14:00 deraadt Exp $ */
+/* $OpenBSD: serverloop.c,v 1.177 2015/02/16 22:13:32 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -79,6 +79,7 @@
#include "auth-options.h"
#include "serverloop.h"
#include "roaming.h"
+#include "ssherr.h"
extern ServerOptions options;
@@ -1150,11 +1151,82 @@
}
static int
+server_input_hostkeys_prove(struct sshbuf **respp)
+{
+ struct ssh *ssh = active_state; /* XXX */
+ struct sshbuf *resp = NULL;
+ struct sshbuf *sigbuf = NULL;
+ struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
+ int r, ndx, success = 0;
+ const u_char *blob;
+ u_char *sig = 0;
+ size_t blen, slen;
+
+ if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new", __func__);
+
+ while (ssh_packet_remaining(ssh) > 0) {
+ sshkey_free(key);
+ key = NULL;
+ if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 ||
+ (r = sshkey_from_blob(blob, blen, &key)) != 0) {
+ error("%s: couldn't parse key: %s",
+ __func__, ssh_err(r));
+ goto out;
+ }
+ /*
+ * Better check that this is actually one of our hostkeys
+ * before attempting to sign anything with it.
+ */
+ if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) {
+ error("%s: unknown host %s key",
+ __func__, sshkey_type(key));
+ goto out;
+ }
+ /*
+ * XXX refactor: make kex->sign just use an index rather
+ * than passing in public and private keys
+ */
+ if ((key_prv = get_hostkey_by_index(ndx)) == NULL &&
+ (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) {
+ error("%s: can't retrieve hostkey %d", __func__, ndx);
+ goto out;
+ }
+ sshbuf_reset(sigbuf);
+ free(sig);
+ sig = NULL;
+ if ((r = sshbuf_put_string(sigbuf,
+ ssh->kex->session_id, ssh->kex->session_id_len)) != 0 ||
+ (r = sshbuf_put_cstring(sigbuf,
+ "hostkeys-prove@openssh.com")) != 0 ||
+ (r = sshkey_puts(key, sigbuf)) != 0 ||
+ (r = ssh->kex->sign(key_prv, key_pub, &sig, &slen,
+ sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), 0)) != 0 ||
+ (r = sshbuf_put_string(resp, sig, slen)) != 0) {
+ error("%s: couldn't prepare signature: %s",
+ __func__, ssh_err(r));
+ goto out;
+ }
+ }
+ /* Success */
+ *respp = resp;
+ resp = NULL; /* don't free it */
+ success = 1;
+ out:
+ free(sig);
+ sshbuf_free(resp);
+ sshbuf_free(sigbuf);
+ sshkey_free(key);
+ return success;
+}
+
+static int
server_input_global_request(int type, u_int32_t seq, void *ctxt)
{
char *rtype;
int want_reply;
- int success = 0, allocated_listen_port = 0;
+ int r, success = 0, allocated_listen_port = 0;
+ struct sshbuf *resp = NULL;
rtype = packet_get_string(NULL);
want_reply = packet_get_char();
@@ -1191,6 +1263,10 @@
&allocated_listen_port, &options.fwd_opts);
}
free(fwd.listen_host);
+ if ((resp = sshbuf_new()) == NULL)
+ fatal("%s: sshbuf_new", __func__);
+ if ((r = sshbuf_put_u32(resp, allocated_listen_port)) != 0)
+ fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r));
} else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
struct Forward fwd;
@@ -1234,16 +1310,20 @@
} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
no_more_sessions = 1;
success = 1;
+ } else if (strcmp(rtype, "hostkeys-prove@openssh.com") == 0) {
+ success = server_input_hostkeys_prove(&resp);
}
if (want_reply) {
packet_start(success ?
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
- if (success && allocated_listen_port > 0)
- packet_put_int(allocated_listen_port);
+ if (success && resp != NULL)
+ ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
+ sshbuf_len(resp));
packet_send();
packet_write_wait();
}
free(rtype);
+ sshbuf_free(resp);
return 0;
}