upstream commit

fix the KEX fuzzer - the previous method of obtaining the
packet contents was broken. This now uses the new per-packet input hook, so
it sees exact post-decrypt packets and doesn't have to pass packet integrity
checks. ok markus@

Upstream-Regress-ID: 402fb6ffabd97de590e8e57b25788949dce8d2fd

1 files changed, 103 insertions, 59 deletions

diff --git a/regress/misc/kexfuzz/kexfuzz.c b/regress/misc/kexfuzz/kexfuzz.c
index 8535980b0..67058027f 100644
--- a/regress/misc/kexfuzz/kexfuzz.c
+++ b/regress/misc/kexfuzz/kexfuzz.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: kexfuzz.c,v 1.2 2016/09/16 01:01:41 djm Exp $ */
+/*      $OpenBSD: kexfuzz.c,v 1.3 2016/10/11 21:49:54 djm Exp $ */
 /*
  * Fuzz harness for KEX code
  *
@@ -27,6 +27,7 @@
 #include "packet.h"
 #include "myproposal.h"
 #include "authfile.h"
+#include "log.h"
 
 struct ssh *active_state = NULL; /* XXX - needed for linking */
 
@@ -35,61 +36,93 @@ static int do_debug = 0;
 
 enum direction { S2C, C2S };
 
+struct hook_ctx {
+        struct ssh *client, *server, *server2;
+        int *c2s, *s2c;
+        int trigger_direction, packet_index;
+        const char *dump_path;
+        struct sshbuf *replace_data;
+};
+
 static int
-do_send_and_receive(struct ssh *from, struct ssh *to, int mydirection,
-    int *packet_count, int trigger_direction, int packet_index,
-    const char *dump_path, struct sshbuf *replace_data)
+packet_hook(struct ssh *ssh, struct sshbuf *packet, u_char *typep, void *_ctx)
+{
+        struct hook_ctx *ctx = (struct hook_ctx *)_ctx;
+        int mydirection = ssh == ctx->client ? S2C : C2S;
+        int *packet_count = mydirection == S2C ? ctx->s2c : ctx->c2s;
+        FILE *dumpfile;
+        int r;
+
+        if (do_debug) {
+                printf("%s packet %d type %u:\n",
+                    mydirection == S2C ? "s2c" : "c2s",
+                    *packet_count, *typep);
+                sshbuf_dump(packet, stdout);
+        }
+        if (mydirection == ctx->trigger_direction &&
+            ctx->packet_index == *packet_count) {
+                if (ctx->replace_data != NULL) {
+                        sshbuf_reset(packet);
+                        /* Type is first byte of packet */
+                        if ((r = sshbuf_get_u8(ctx->replace_data,
+                            typep)) != 0 ||
+                            (r = sshbuf_putb(packet, ctx->replace_data)) != 0)
+                                return r;
+                        if (do_debug) {
+                                printf("***** replaced packet type %u\n",
+                                    *typep);
+                                sshbuf_dump(packet, stdout);
+                        }
+                } else if (ctx->dump_path != NULL) {
+                        if ((dumpfile = fopen(ctx->dump_path, "w+")) == NULL)
+                                err(1, "fopen %s", ctx->dump_path);
+                        /* Write { type, packet } */
+                        if (fwrite(typep, 1, 1, dumpfile) != 1)
+                                err(1, "fwrite type %s", ctx->dump_path);
+                        if (sshbuf_len(packet) != 0 &&
+                            fwrite(sshbuf_ptr(packet), sshbuf_len(packet),
+                            1, dumpfile) != 1)
+                                err(1, "fwrite body %s", ctx->dump_path);
+                        if (do_debug) {
+                                printf("***** dumped packet type %u len %zu\n",
+                                    *typep, sshbuf_len(packet));
+                        }
+                        fclose(dumpfile);
+                        /* No point in continuing */
+                        exit(0);
+                }
+        }
+        (*packet_count)++;
+        return 0;
+}
+
+static int
+do_send_and_receive(struct ssh *from, struct ssh *to)
 {
         u_char type;
-        size_t len, olen;
+        size_t len;
         const u_char *buf;
         int r;
-        FILE *dumpfile;
 
         for (;;) {
                 if ((r = ssh_packet_next(from, &type)) != 0) {
                         fprintf(stderr, "ssh_packet_next: %s\n", ssh_err(r));
                         return r;
                 }
+
                 if (type != 0)
                         return 0;
                 buf = ssh_output_ptr(from, &len);
-                olen = len;
-                if (do_debug) {
-                        printf("%s packet %d type %u len %zu:\n",
-                            mydirection == S2C ? "s2c" : "c2s",
-                            *packet_count, type, len);
-                        sshbuf_dump_data(buf, len, stdout);
-                }
-                if (mydirection == trigger_direction &&
-                    packet_index == *packet_count) {
-                        if (replace_data != NULL) {
-                                buf = sshbuf_ptr(replace_data);
-                                len = sshbuf_len(replace_data);
-                                if (do_debug) {
-                                        printf("***** replaced packet "
-                                            "len %zu\n", len);
-                                        sshbuf_dump_data(buf, len, stdout);
-                                }
-                        } else if (dump_path != NULL) {
-                                if ((dumpfile = fopen(dump_path, "w+")) == NULL)
-                                        err(1, "fopen %s", dump_path);
-                                if (len != 0 &&
-                                    fwrite(buf, len, 1, dumpfile) != 1)
-                                        err(1, "fwrite %s", dump_path);
-                                if (do_debug)
-                                        printf("***** dumped packet "
-                                            "len %zu\n", len);
-                                fclose(dumpfile);
-                                exit(0);
-                        }
-                }
-                (*packet_count)++;
                 if (len == 0)
                         return 0;
-                if ((r = ssh_input_append(to, buf, len)) != 0 ||
-                    (r = ssh_output_consume(from, olen)) != 0)
+                if ((r = ssh_input_append(to, buf, len)) != 0) {
+                        debug("ssh_input_append: %s", ssh_err(r));
+                        return r;
+                }
+                if ((r = ssh_output_consume(from, len)) != 0) {
+                        debug("ssh_output_consume: %s", ssh_err(r));
                         return r;
+                }
         }
 }
 
@@ -141,19 +174,19 @@ const char *in_test = NULL;
 
 
 static void
-run_kex(struct ssh *client, struct ssh *server, int *s2c, int *c2s,
-    int direction, int packet_index,
-    const char *dump_path, struct sshbuf *replace_data)
+run_kex(struct ssh *client, struct ssh *server)
 {
         int r = 0;
 
         while (!server->kex->done || !client->kex->done) {
-                if ((r = do_send_and_receive(server, client, S2C, s2c,
-                    direction, packet_index, dump_path, replace_data)))
+                if ((r = do_send_and_receive(server, client)) != 0) {
+                        debug("do_send_and_receive S2C: %s", ssh_err(r));
                         break;
-                if ((r = do_send_and_receive(client, server, C2S, c2s,
-                    direction, packet_index, dump_path, replace_data)))
+                }
+                if ((r = do_send_and_receive(client, server)) != 0) {
+                        debug("do_send_and_receive C2S: %s", ssh_err(r));
                         break;
+                }
         }
         if (do_debug)
                 printf("done: %s\n", ssh_err(r));
@@ -173,6 +206,7 @@ do_kex_with_key(const char *kex, struct sshkey *prvkey, int *c2s, int *s2c,
         struct kex_params kex_params;
         char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
         char *keyname = NULL;
+        struct hook_ctx hook_ctx;
 
         TEST_START("sshkey_from_private");
         ASSERT_INT_EQ(sshkey_from_private(prvkey, &pubkey), 0);
@@ -187,30 +221,42 @@ do_kex_with_key(const char *kex, struct sshkey *prvkey, int *c2s, int *s2c,
         kex_params.proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = keyname;
         ASSERT_INT_EQ(ssh_init(&client, 0, &kex_params), 0);
         ASSERT_INT_EQ(ssh_init(&server, 1, &kex_params), 0);
+        ASSERT_INT_EQ(ssh_init(&server2, 1, NULL), 0);
         ASSERT_PTR_NE(client, NULL);
         ASSERT_PTR_NE(server, NULL);
+        ASSERT_PTR_NE(server2, NULL);
         TEST_DONE();
 
+        hook_ctx.c2s = c2s;
+        hook_ctx.s2c = s2c;
+        hook_ctx.trigger_direction = direction;
+        hook_ctx.packet_index = packet_index;
+        hook_ctx.dump_path = dump_path;
+        hook_ctx.replace_data = replace_data;
+        hook_ctx.client = client;
+        hook_ctx.server = server;
+        hook_ctx.server2 = server2;
+        ssh_packet_set_input_hook(client, packet_hook, &hook_ctx);
+        ssh_packet_set_input_hook(server, packet_hook, &hook_ctx);
+        ssh_packet_set_input_hook(server2, packet_hook, &hook_ctx);
+
         TEST_START("ssh_add_hostkey");
         ASSERT_INT_EQ(ssh_add_hostkey(server, prvkey), 0);
         ASSERT_INT_EQ(ssh_add_hostkey(client, pubkey), 0);
         TEST_DONE();
 
         TEST_START("kex");
-        run_kex(client, server, s2c, c2s, direction, packet_index,
-            dump_path, replace_data);
+        run_kex(client, server);
         TEST_DONE();
 
         TEST_START("rekeying client");
         ASSERT_INT_EQ(kex_send_kexinit(client), 0);
-        run_kex(client, server, s2c, c2s, direction, packet_index,
-            dump_path, replace_data);
+        run_kex(client, server);
         TEST_DONE();
 
         TEST_START("rekeying server");
         ASSERT_INT_EQ(kex_send_kexinit(server), 0);
-        run_kex(client, server, s2c, c2s, direction, packet_index,
-            dump_path, replace_data);
+        run_kex(client, server);
         TEST_DONE();
 
         TEST_START("ssh_packet_get_state");
@@ -221,9 +267,6 @@ do_kex_with_key(const char *kex, struct sshkey *prvkey, int *c2s, int *s2c,
         TEST_DONE();
 
         TEST_START("ssh_packet_set_state");
-        server2 = NULL;
-        ASSERT_INT_EQ(ssh_init(&server2, 1, NULL), 0);
-        ASSERT_PTR_NE(server2, NULL);
         ASSERT_INT_EQ(ssh_add_hostkey(server2, prvkey), 0);
         kex_free(server2->kex); /* XXX or should ssh_packet_set_state()? */
         ASSERT_INT_EQ(ssh_packet_set_state(server2, state), 0);
@@ -251,11 +294,9 @@ do_kex_with_key(const char *kex, struct sshkey *prvkey, int *c2s, int *s2c,
 
         TEST_START("rekeying server2");
         ASSERT_INT_EQ(kex_send_kexinit(server2), 0);
-        run_kex(client, server2, s2c, c2s, direction, packet_index,
-            dump_path, replace_data);
+        run_kex(client, server2);
         ASSERT_INT_EQ(kex_send_kexinit(client), 0);
-        run_kex(client, server2, s2c, c2s, direction, packet_index,
-            dump_path, replace_data);
+        run_kex(client, server2);
         TEST_DONE();
 
         TEST_START("cleanup");
@@ -357,6 +398,9 @@ main(int argc, char **argv)
         argc -= optind;
         argv += optind;
 
+        log_init(argv[0], do_debug ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
+            SYSLOG_FACILITY_USER, 1);
+
         /* Must select a single mode */
         if ((count_flag + dump_flag + replace_flag) != 1)
                 badusage("Must select one mode: -c, -d or -r");