upstream commit

clear session keys from memory; ok djm@

Upstream-ID: ecd178819868975affd5fd6637458b7c712b6a0f

1 files changed, 61 insertions, 35 deletions

diff --git a/packet.c b/packet.c
index 46dcc5b5f..862aeb052 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.256 2017/05/08 06:03:39 djm Exp $ */
+/* $OpenBSD: packet.c,v 1.257 2017/05/31 08:09:45 markus Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -559,8 +559,8 @@ ssh_local_port(struct ssh *ssh)
 
 /* Closes the connection and clears and frees internal data structures. */
 
-void
-ssh_packet_close(struct ssh *ssh)
+static void
+ssh_packet_close_internal(struct ssh *ssh, int do_close)
 {
         struct session_state *state = ssh->state;
         u_int mode;
@@ -568,20 +568,26 @@ ssh_packet_close(struct ssh *ssh)
         if (!state->initialized)
                 return;
         state->initialized = 0;
-        if (state->connection_in == state->connection_out) {
-                shutdown(state->connection_out, SHUT_RDWR);
-                close(state->connection_out);
-        } else {
-                close(state->connection_in);
-                close(state->connection_out);
+        if (do_close) {
+                if (state->connection_in == state->connection_out) {
+                        shutdown(state->connection_out, SHUT_RDWR);
+                        close(state->connection_out);
+                } else {
+                        close(state->connection_in);
+                        close(state->connection_out);
+                }
         }
         sshbuf_free(state->input);
         sshbuf_free(state->output);
         sshbuf_free(state->outgoing_packet);
         sshbuf_free(state->incoming_packet);
-        for (mode = 0; mode < MODE_MAX; mode++)
-                kex_free_newkeys(state->newkeys[mode]);
-        if (state->compression_buffer) {
+        for (mode = 0; mode < MODE_MAX; mode++) {
+                kex_free_newkeys(state->newkeys[mode]); /* current keys */
+                state->newkeys[mode] = NULL;
+                ssh_clear_newkeys(ssh, mode);           /* next keys */
+        }
+        /* comression state is in shared mem, so we can only release it once */
+        if (do_close && state->compression_buffer) {
                 sshbuf_free(state->compression_buffer);
                 if (state->compression_out_started) {
                         z_streamp stream = &state->compression_out_stream;
@@ -609,10 +615,24 @@ ssh_packet_close(struct ssh *ssh)
         cipher_free(state->send_context);
         cipher_free(state->receive_context);
         state->send_context = state->receive_context = NULL;
-        free(ssh->remote_ipaddr);
-        ssh->remote_ipaddr = NULL;
-        free(ssh->state);
-        ssh->state = NULL;
+        if (do_close) {
+                free(ssh->remote_ipaddr);
+                ssh->remote_ipaddr = NULL;
+                free(ssh->state);
+                ssh->state = NULL;
+        }
+}
+
+void
+ssh_packet_close(struct ssh *ssh)
+{
+        ssh_packet_close_internal(ssh, 1);
+}
+
+void
+ssh_packet_clear_keys(struct ssh *ssh)
+{
+        ssh_packet_close_internal(ssh, 0);
 }
 
 /* Sets remote side protocol flags. */
@@ -791,6 +811,15 @@ uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
         /* NOTREACHED */
 }
 
+void
+ssh_clear_newkeys(struct ssh *ssh, int mode)
+{
+        if (ssh->kex && ssh->kex->newkeys) {
+                kex_free_newkeys(ssh->kex->newkeys[mode]);
+                ssh->kex->newkeys[mode] = NULL;
+        }
+}
+
 int
 ssh_set_newkeys(struct ssh *ssh, int mode)
 {
@@ -820,26 +849,16 @@ ssh_set_newkeys(struct ssh *ssh, int mode)
                 max_blocks = &state->max_blocks_in;
         }
         if (state->newkeys[mode] != NULL) {
-                debug("%s: rekeying after %llu %s blocks"
-                    " (%llu bytes total)", __func__,
-                    (unsigned long long)ps->blocks, dir,
-                    (unsigned long long)ps->bytes);
+                debug("set_newkeys: rekeying, input %llu bytes %llu blocks, "
+                   "output %llu bytes %llu blocks",
+                   (unsigned long long)state->p_read.bytes,
+                   (unsigned long long)state->p_read.blocks,
+                   (unsigned long long)state->p_send.bytes,
+                   (unsigned long long)state->p_send.blocks);
                 cipher_free(*ccp);
                 *ccp = NULL;
-                enc  = &state->newkeys[mode]->enc;
-                mac  = &state->newkeys[mode]->mac;
-                comp = &state->newkeys[mode]->comp;
-                mac_clear(mac);
-                explicit_bzero(enc->iv,  enc->iv_len);
-                explicit_bzero(enc->key, enc->key_len);
-                explicit_bzero(mac->key, mac->key_len);
-                free(enc->name);
-                free(enc->iv);
-                free(enc->key);
-                free(mac->name);
-                free(mac->key);
-                free(comp->name);
-                free(state->newkeys[mode]);
+                kex_free_newkeys(state->newkeys[mode]);
+                state->newkeys[mode] = NULL;
         }
         /* note that both bytes and the seqnr are not reset */
         ps->packets = ps->blocks = 0;
@@ -1784,15 +1803,20 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
 
         switch (r) {
         case SSH_ERR_CONN_CLOSED:
+                ssh_packet_clear_keys(ssh);
                 logdie("Connection closed by %s", remote_id);
         case SSH_ERR_CONN_TIMEOUT:
+                ssh_packet_clear_keys(ssh);
                 logdie("Connection %s %s timed out",
                     ssh->state->server_side ? "from" : "to", remote_id);
         case SSH_ERR_DISCONNECTED:
+                ssh_packet_clear_keys(ssh);
                 logdie("Disconnected from %s", remote_id);
         case SSH_ERR_SYSTEM_ERROR:
-                if (errno == ECONNRESET)
+                if (errno == ECONNRESET) {
+                        ssh_packet_clear_keys(ssh);
                         logdie("Connection reset by %s", remote_id);
+                }
                 /* FALLTHROUGH */
         case SSH_ERR_NO_CIPHER_ALG_MATCH:
         case SSH_ERR_NO_MAC_ALG_MATCH:
@@ -1800,12 +1824,14 @@ sshpkt_fatal(struct ssh *ssh, const char *tag, int r)
         case SSH_ERR_NO_KEX_ALG_MATCH:
         case SSH_ERR_NO_HOSTKEY_ALG_MATCH:
                 if (ssh && ssh->kex && ssh->kex->failed_choice) {
+                        ssh_packet_clear_keys(ssh);
                         logdie("Unable to negotiate with %s: %s. "
                             "Their offer: %s", remote_id, ssh_err(r),
                             ssh->kex->failed_choice);
                 }
                 /* FALLTHROUGH */
         default:
+                ssh_packet_clear_keys(ssh);
                 logdie("%s%sConnection %s %s: %s",
                     tag != NULL ? tag : "", tag != NULL ? ": " : "",
                     ssh->state->server_side ? "from" : "to",