- (djm) OpenBSD CVS Sync

   - markus@cvs.openbsd.org 2003/04/02 09:48:07
     [clientloop.c monitor.c monitor_wrap.c packet.c packet.h readconf.c]
     [readconf.h serverloop.c sshconnect2.c]
     reapply rekeying chage, tested by henning@, ok djm@

1 files changed, 123 insertions, 22 deletions

diff --git a/packet.c b/packet.c
index 254e452d0..9887d25af 100644
--- a/packet.c
+++ b/packet.c
@@ -37,7 +37,9 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: packet.c,v 1.104 2003/04/01 10:22:21 markus Exp $");
+RCSID("$OpenBSD: packet.c,v 1.105 2003/04/02 09:48:07 markus Exp $");
+
+#include <sys/queue.h>
 
 #include "xmalloc.h"
 #include "buffer.h"
@@ -116,8 +118,14 @@ static int interactive_mode = 0;
 
 /* Session key information for Encryption and MAC */
 Newkeys *newkeys[MODE_MAX];
-static u_int32_t read_seqnr = 0;
-static u_int32_t send_seqnr = 0;
+static struct packet_state {
+        u_int32_t seqnr;
+        u_int32_t packets;
+        u_int64_t blocks;
+} p_read, p_send;
+
+static u_int64_t max_blocks_in, max_blocks_out;
+static u_int32_t rekey_limit;
 
 /* Session key for protocol v1 */
 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
@@ -126,6 +134,13 @@ static u_int ssh1_keylen;
 /* roundup current message to extra_pad bytes */
 static u_char extra_pad = 0;
 
+struct packet {
+        TAILQ_ENTRY(packet) next;
+        u_char type;
+        Buffer payload;
+};
+TAILQ_HEAD(, packet) outgoing;
+
 /*
  * Sets the descriptors used for communication.  Disables encryption until
  * packet_set_encryption_key is called.
@@ -148,6 +163,7 @@ packet_set_connection(int fd_in, int fd_out)
                 buffer_init(&output);
                 buffer_init(&outgoing_packet);
                 buffer_init(&incoming_packet);
+                TAILQ_INIT(&outgoing);
         }
         /* Kludge: arrange the close function to be called from fatal(). */
         fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
@@ -254,22 +270,26 @@ packet_get_ssh1_cipher()
         return (cipher_get_number(receive_context.cipher));
 }
 
-
-u_int32_t
-packet_get_seqnr(int mode)
+void
+packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets)
 {
-        return (mode == MODE_IN ? read_seqnr : send_seqnr);
+        struct packet_state *state;
+
+        state = (mode == MODE_IN) ? &p_read : &p_send;
+        *seqnr = state->seqnr;
+        *blocks = state->blocks;
+        *packets = state->packets;
 }
 
 void
-packet_set_seqnr(int mode, u_int32_t seqnr)
+packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets)
 {
-        if (mode == MODE_IN)
-                read_seqnr = seqnr;
-        else if (mode == MODE_OUT)
-                send_seqnr = seqnr;
-        else
-                fatal("packet_set_seqnr: bad mode %d", mode);
+        struct packet_state *state;
+
+        state = (mode == MODE_IN) ? &p_read : &p_send;
+        state->seqnr = seqnr;
+        state->blocks = blocks;
+        state->packets = packets;
 }
 
 /* returns 1 if connection is via ipv4 */
@@ -562,6 +582,7 @@ set_newkeys(int mode)
         Mac *mac;
         Comp *comp;
         CipherContext *cc;
+        u_int64_t *max_blocks;
         int encrypt;
 
         debug2("set_newkeys: mode %d", mode);
@@ -569,9 +590,13 @@ set_newkeys(int mode)
         if (mode == MODE_OUT) {
                 cc = &send_context;
                 encrypt = CIPHER_ENCRYPT;
+                p_send.packets = p_send.blocks = 0;
+                max_blocks = &max_blocks_out;
         } else {
                 cc = &receive_context;
                 encrypt = CIPHER_DECRYPT;
+                p_read.packets = p_read.blocks = 0;
+                max_blocks = &max_blocks_in;
         }
         if (newkeys[mode] != NULL) {
                 debug("set_newkeys: rekeying");
@@ -610,13 +635,16 @@ set_newkeys(int mode)
                         buffer_compress_init_recv();
                 comp->enabled = 1;
         }
+        *max_blocks = ((u_int64_t)1 << (enc->block_size*2));
+        if (rekey_limit)
+                *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
 }
 
 /*
  * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
  */
 static void
-packet_send2(void)
+packet_send2_wrapped(void)
 {
         u_char type, *cp, *macbuf = NULL;
         u_char padlen, pad;
@@ -698,10 +726,10 @@ packet_send2(void)
 
         /* compute MAC over seqnr and packet(length fields, payload, padding) */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, send_seqnr,
+                macbuf = mac_compute(mac, p_send.seqnr,
                     buffer_ptr(&outgoing_packet),
                     buffer_len(&outgoing_packet));
-                DBG(debug("done calc MAC out #%d", send_seqnr));
+                DBG(debug("done calc MAC out #%d", p_send.seqnr));
         }
         /* encrypt packet and append to output buffer. */
         cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
@@ -715,14 +743,64 @@ packet_send2(void)
         buffer_dump(&output);
 #endif
         /* increment sequence number for outgoing packets */
-        if (++send_seqnr == 0)
+        if (++p_send.seqnr == 0)
                 log("outgoing seqnr wraps around");
+        if (++p_send.packets == 0)
+                if (!(datafellows & SSH_BUG_NOREKEY))
+                        fatal("XXX too many packets with same key");
+        p_send.blocks += (packet_length + 4) / block_size;
         buffer_clear(&outgoing_packet);
 
         if (type == SSH2_MSG_NEWKEYS)
                 set_newkeys(MODE_OUT);
 }
 
+static void
+packet_send2(void)
+{
+        static int rekeying = 0;
+        struct packet *p;
+        u_char type, *cp;
+
+        cp = buffer_ptr(&outgoing_packet);
+        type = cp[5];
+
+        /* during rekeying we can only send key exchange messages */
+        if (rekeying) {
+                if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
+                    (type <= SSH2_MSG_TRANSPORT_MAX))) {
+                        debug("enqueue packet: %u", type);
+                        p = xmalloc(sizeof(*p));
+                        p->type = type;
+                        memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
+                        buffer_init(&outgoing_packet);
+                        TAILQ_INSERT_TAIL(&outgoing, p, next);
+                        return;
+                }
+        }
+
+        /* rekeying starts with sending KEXINIT */
+        if (type == SSH2_MSG_KEXINIT)
+                rekeying = 1;
+
+        packet_send2_wrapped();
+
+        /* after a NEWKEYS message we can send the complete queue */
+        if (type == SSH2_MSG_NEWKEYS) {
+                rekeying = 0;
+                while ((p = TAILQ_FIRST(&outgoing))) {
+                        type = p->type;
+                        debug("dequeue packet: %u", type);
+                        buffer_free(&outgoing_packet);
+                        memcpy(&outgoing_packet, &p->payload,
+                            sizeof(Buffer));
+                        TAILQ_REMOVE(&outgoing, p, next);
+                        xfree(p);
+                        packet_send2_wrapped();
+                }
+        }
+}
+
 void
 packet_send(void)
 {
@@ -966,18 +1044,22 @@ packet_read_poll2(u_int32_t *seqnr_p)
          * increment sequence number for incoming packet
          */
         if (mac && mac->enabled) {
-                macbuf = mac_compute(mac, read_seqnr,
+                macbuf = mac_compute(mac, p_read.seqnr,
                     buffer_ptr(&incoming_packet),
                     buffer_len(&incoming_packet));
                 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
                         packet_disconnect("Corrupted MAC on input.");
-                DBG(debug("MAC #%d ok", read_seqnr));
+                DBG(debug("MAC #%d ok", p_read.seqnr));
                 buffer_consume(&input, mac->mac_len);
         }
         if (seqnr_p != NULL)
-                *seqnr_p = read_seqnr;
-        if (++read_seqnr == 0)
+                *seqnr_p = p_read.seqnr;
+        if (++p_read.seqnr == 0)
                 log("incoming seqnr wraps around");
+        if (++p_read.packets == 0)
+                if (!(datafellows & SSH_BUG_NOREKEY))
+                        fatal("XXX too many packets with same key");
+        p_read.blocks += (packet_length + 4) / block_size;
 
         /* get padlen */
         cp = buffer_ptr(&incoming_packet);
@@ -1416,3 +1498,22 @@ packet_send_ignore(int nbytes)
                 rand >>= 8;
         }
 }
+
+#define MAX_PACKETS     (1<<31)
+int
+packet_need_rekeying(void)
+{
+        if (datafellows & SSH_BUG_NOREKEY)
+                return 0;
+        return
+            (p_send.packets > MAX_PACKETS) ||
+            (p_read.packets > MAX_PACKETS) ||
+            (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
+            (max_blocks_in  && (p_read.blocks > max_blocks_in));
+}
+
+void
+packet_set_rekey_limit(u_int32_t bytes)
+{
+        rekey_limit = bytes;
+}