upstream commit

add KEX fuzzer harness; ok deraadt@

Upstream-Regress-ID: 3df5242d30551b12b828aa9ba4a4cec0846be8d1

regress/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.82 2015/09/24 06:16:53 djm Exp $
+#	$OpenBSD: Makefile,v 1.84 2016/03/04 02:30:36 djm Exp $
 
 REGRESS_TARGETS=	unit t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t-exec
 tests:		prep $(REGRESS_TARGETS)

regress/misc/Makefile

@@ -0,0 +1,3 @@
+SUBDIR=		kexfuzz
+
+.include <bsd.subdir.mk>

regress/misc/kexfuzz/Makefile

@@ -0,0 +1,78 @@
+#	$OpenBSD: Makefile,v 1.1 2016/03/04 02:30:37 djm Exp $
+
+.include <bsd.own.mk>
+.include <bsd.obj.mk>
+
+# XXX detect from ssh binary?
+SSH1?=		no
+OPENSSL?=	yes
+
+PROG=	kexfuzz
+SRCS=	kexfuzz.c
+NOMAN=	1
+
+.if (${OPENSSL:L} == "yes")
+CFLAGS+=	-DWITH_OPENSSL
+.else
+# SSH v.1 requires OpenSSL.
+SSH1=		no
+.endif
+
+.if (${SSH1:L} == "yes")
+CFLAGS+=	-DWITH_SSH1
+.endif
+
+# enable warnings
+WARNINGS=Yes
+
+DEBUG=-g
+CFLAGS+=	-fstack-protector-all
+CDIAGFLAGS=	-Wall
+CDIAGFLAGS+=	-Wextra
+CDIAGFLAGS+=	-Werror
+CDIAGFLAGS+=	-Wchar-subscripts
+CDIAGFLAGS+=	-Wcomment
+CDIAGFLAGS+=	-Wformat
+CDIAGFLAGS+=	-Wformat-security
+CDIAGFLAGS+=	-Wimplicit
+CDIAGFLAGS+=	-Winline
+CDIAGFLAGS+=	-Wmissing-declarations
+CDIAGFLAGS+=	-Wmissing-prototypes
+CDIAGFLAGS+=	-Wparentheses
+CDIAGFLAGS+=	-Wpointer-arith
+CDIAGFLAGS+=	-Wreturn-type
+CDIAGFLAGS+=	-Wshadow
+CDIAGFLAGS+=	-Wsign-compare
+CDIAGFLAGS+=	-Wstrict-aliasing
+CDIAGFLAGS+=	-Wstrict-prototypes
+CDIAGFLAGS+=	-Wswitch
+CDIAGFLAGS+=	-Wtrigraphs
+CDIAGFLAGS+=	-Wuninitialized
+CDIAGFLAGS+=	-Wunused
+.if ${COMPILER_VERSION} == "gcc4"
+CDIAGFLAGS+=	-Wpointer-sign
+CDIAGFLAGS+=	-Wold-style-definition
+.endif
+
+SSHREL=../../../../../usr.bin/ssh
+
+CFLAGS+=-I${.CURDIR}/${SSHREL}
+
+.if exists(${.CURDIR}/${SSHREL}/lib/${__objdir})
+LDADD+=-L${.CURDIR}/${SSHREL}/lib/${__objdir} -lssh
+DPADD+=${.CURDIR}/${SSHREL}/lib/${__objdir}/libssh.a
+.else
+LDADD+=-L${.CURDIR}/${SSHREL}/lib -lssh
+DPADD+=${.CURDIR}/${SSHREL}/lib/libssh.a
+.endif
+
+LDADD+= -lutil -lz
+DPADD+= ${LIBUTIL} ${LIBZ}
+
+.if (${OPENSSL:L} == "yes")
+LDADD+= -lcrypto
+DPADD+= ${LIBCRYPTO}
+.endif
+
+.include <bsd.prog.mk>
+

regress/misc/kexfuzz/README

@@ -0,0 +1,28 @@
+This is a harness to help with fuzzing KEX.
+
+To use it, you first set it to count packets in each direction:
+
+./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key -c
+S2C: 29
+C2S: 31
+
+Then get it to record a particular packet (in this case the 4th
+packet from client->server):
+
+./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key \
+    -d -D C2S -i 3 -f packet_3
+
+Fuzz the packet somehow:
+
+dd if=/dev/urandom of=packet_3 bs=32 count=1 # Just for example
+
+Then re-run the key exchange substituting the modified packet in
+its original sequence:
+
+./kexfuzz -K diffie-hellman-group1-sha1 -k host_ed25519_key \
+    -r -D C2S -i 3 -f packet_3
+
+A comprehensive KEX fuzz run would fuzz every packet in both
+directions for each key exchange type and every hostkey type.
+This will take some time.
+

regress/misc/kexfuzz/kexfuzz.c

@@ -0,0 +1,404 @@
+/* 	$OpenBSD: kexfuzz.c,v 1.1 2016/03/04 02:30:37 djm Exp $ */
+/*
+ * Fuzz harness for KEX code
+ *
+ * Placed in the public domain
+ */
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <err.h>
+
+#include "ssherr.h"
+#include "ssh_api.h"
+#include "sshbuf.h"
+#include "packet.h"
+#include "myproposal.h"
+#include "authfile.h"
+
+struct ssh *active_state = NULL; /* XXX - needed for linking */
+
+void kex_tests(void);
+static int do_debug = 0;
+
+enum direction { S2C, C2S };
+
+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)
+{
+	u_char type;
+	size_t len, olen;
+	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)
+			return r;
+	}
+}
+
+/* Minimal test_helper.c scaffholding to make this standalone */
+const char *in_test = NULL;
+#define TEST_START(a)	\
+	do { \
+		in_test = (a); \
+		if (do_debug) \
+			fprintf(stderr, "test %s starting\n", in_test); \
+	} while (0)
+#define TEST_DONE()	\
+	do { \
+		if (do_debug) \
+			fprintf(stderr, "test %s done\n", \
+			    in_test ? in_test : "???"); \
+		in_test = NULL; \
+	} while(0)
+#define ASSERT_INT_EQ(a, b) \
+	do { \
+		if ((int)(a) != (int)(b)) { \
+			fprintf(stderr, "%s %s:%d " \
+			    "%s (%d) != expected %s (%d)\n", \
+			    in_test ? in_test : "(none)", \
+			    __func__, __LINE__, #a, (int)(a), #b, (int)(b)); \
+			exit(2); \
+		} \
+	} while (0)
+#define ASSERT_INT_GE(a, b) \
+	do { \
+		if ((int)(a) < (int)(b)) { \
+			fprintf(stderr, "%s %s:%d " \
+			    "%s (%d) < expected %s (%d)\n", \
+			    in_test ? in_test : "(none)", \
+			    __func__, __LINE__, #a, (int)(a), #b, (int)(b)); \
+			exit(2); \
+		} \
+	} while (0)
+#define ASSERT_PTR_NE(a, b) \
+	do { \
+		if ((a) == (b)) { \
+			fprintf(stderr, "%s %s:%d " \
+			    "%s (%p) != expected %s (%p)\n", \
+			    in_test ? in_test : "(none)", \
+			    __func__, __LINE__, #a, (a), #b, (b)); \
+			exit(2); \
+		} \
+	} while (0)
+
+
+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)
+{
+	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)))
+			break;
+		if ((r = do_send_and_receive(client, server, C2S, c2s,
+		    direction, packet_index, dump_path, replace_data)))
+			break;
+	}
+	if (do_debug)
+		printf("done: %s\n", ssh_err(r));
+	ASSERT_INT_EQ(r, 0);
+	ASSERT_INT_EQ(server->kex->done, 1);
+	ASSERT_INT_EQ(client->kex->done, 1);
+}
+
+static void
+do_kex_with_key(const char *kex, struct sshkey *prvkey, int *c2s, int *s2c,
+    int direction, int packet_index,
+    const char *dump_path, struct sshbuf *replace_data)
+{
+	struct ssh *client = NULL, *server = NULL, *server2 = NULL;
+	struct sshkey *pubkey = NULL;
+	struct sshbuf *state;
+	struct kex_params kex_params;
+	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
+	char *keyname = NULL;
+
+	TEST_START("sshkey_from_private");
+	ASSERT_INT_EQ(sshkey_from_private(prvkey, &pubkey), 0);
+	TEST_DONE();
+
+	TEST_START("ssh_init");
+	memcpy(kex_params.proposal, myproposal, sizeof(myproposal));
+	if (kex != NULL)
+		kex_params.proposal[PROPOSAL_KEX_ALGS] = strdup(kex);
+	keyname = strdup(sshkey_ssh_name(prvkey));
+	ASSERT_PTR_NE(keyname, NULL);
+	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_PTR_NE(client, NULL);
+	ASSERT_PTR_NE(server, NULL);
+	TEST_DONE();
+
+	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);
+	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);
+	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);
+	TEST_DONE();
+
+	TEST_START("ssh_packet_get_state");
+	state = sshbuf_new();
+	ASSERT_PTR_NE(state, NULL);
+	ASSERT_INT_EQ(ssh_packet_get_state(server, state), 0);
+	ASSERT_INT_GE(sshbuf_len(state), 1);
+	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);
+	ASSERT_INT_EQ(sshbuf_len(state), 0);
+	sshbuf_free(state);
+	ASSERT_PTR_NE(server2->kex, NULL);
+	/* XXX we need to set the callbacks */
+	server2->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+	server2->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
+	server2->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
+	server2->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
+#ifdef OPENSSL_HAS_ECC
+	server2->kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
+#endif
+	server2->kex->kex[KEX_C25519_SHA256] = kexc25519_server;
+	server2->kex->load_host_public_key = server->kex->load_host_public_key;
+	server2->kex->load_host_private_key = server->kex->load_host_private_key;
+	server2->kex->sign = server->kex->sign;
+	TEST_DONE();
+
+	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);
+	ASSERT_INT_EQ(kex_send_kexinit(client), 0);
+	run_kex(client, server2, s2c, c2s, direction, packet_index,
+	    dump_path, replace_data);
+	TEST_DONE();
+
+	TEST_START("cleanup");
+	sshkey_free(pubkey);
+	ssh_free(client);
+	ssh_free(server);
+	ssh_free(server2);
+	free(keyname);
+	TEST_DONE();
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr,
+	    "Usage: kexfuzz [-hcdrv] [-D direction] [-f data_file]\n"
+	    "               [-K kex_alg] [-k private_key] [-i packet_index]\n"
+	    "\n"
+	    "Options:\n"
+	    "    -h               Display this help\n"
+	    "    -c               Count packets sent during KEX\n"
+	    "    -d               Dump mode: record KEX packet to data file\n"
+	    "    -r               Replace mode: replace packet with data file\n"
+	    "    -v               Turn on verbose logging\n"
+	    "    -D S2C|C2S       Packet direction for replacement or dump\n"
+	    "    -f data_file     Path to data file for replacement or dump\n"
+	    "    -K kex_alg       Name of KEX algorithm to test (see below)\n"
+	    "    -k private_key   Path to private key file\n"
+	    "    -i packet_index  Index of packet to replace or dump (from 0)\n"
+	    "\n"
+	    "Available KEX algorithms: %s\n", kex_alg_list(' '));
+}
+
+static void
+badusage(const char *bad)
+{
+	fprintf(stderr, "Invalid options\n");
+	fprintf(stderr, "%s\n", bad);
+	usage();
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	int ch, fd, r;
+	int count_flag = 0, dump_flag = 0, replace_flag = 0;
+	int packet_index = -1, direction = -1;
+	int s2c = 0, c2s = 0; /* packet counts */
+	const char *kex = NULL, *kpath = NULL, *data_path = NULL;
+	struct sshkey *key = NULL;
+	struct sshbuf *replace_data = NULL;
+
+	setvbuf(stdout, NULL, _IONBF, 0);
+	while ((ch = getopt(argc, argv, "hcdrvD:f:K:k:i:")) != -1) {
+		switch (ch) {
+		case 'h':
+			usage();
+			return 0;
+		case 'c':
+			count_flag = 1;
+			break;
+		case 'd':
+			dump_flag = 1;
+			break;
+		case 'r':
+			replace_flag = 1;
+			break;
+		case 'v':
+			do_debug = 1;
+			break;
+
+		case 'D':
+			if (strcasecmp(optarg, "s2c") == 0)
+				direction = S2C;
+			else if (strcasecmp(optarg, "c2s") == 0)
+				direction = C2S;
+			else
+				badusage("Invalid direction (-D)");
+			break;
+		case 'f':
+			data_path = optarg;
+			break;
+		case 'K':
+			kex = optarg;
+			break;
+		case 'k':
+			kpath = optarg;
+			break;
+		case 'i':
+			packet_index = atoi(optarg);
+			if (packet_index < 0)
+				badusage("Invalid packet index");
+			break;
+		default:
+			badusage("unsupported flag");
+		}
+	}
+	argc -= optind;
+	argv += optind;
+
+	/* Must select a single mode */
+	if ((count_flag + dump_flag + replace_flag) != 1)
+		badusage("Must select one mode: -c, -d or -r");
+	/* KEX type is mandatory */
+	if (kex == NULL || !kex_names_valid(kex) || strchr(kex, ',') != NULL)
+		badusage("Missing or invalid kex type (-K flag)");
+	/* Valid key is mandatory */
+	if (kpath == NULL)
+		badusage("Missing private key (-k flag)");
+	if ((fd = open(kpath, O_RDONLY)) == -1)
+		err(1, "open %s", kpath);
+	if ((r = sshkey_load_private_type_fd(fd, KEY_UNSPEC, NULL,
+	    &key, NULL)) != 0)
+		errx(1, "Unable to load key %s: %s", kpath, ssh_err(r));
+	close(fd);
+	/* XXX check that it is a private key */
+	/* XXX support certificates */
+	if (key == NULL || key->type == KEY_UNSPEC || key->type == KEY_RSA1)
+		badusage("Invalid key file (-k flag)");
+
+	/* Replace (fuzz) mode */
+	if (replace_flag) {
+		if (packet_index == -1 || direction == -1 || data_path == NULL)
+			badusage("Replace (-r) mode must specify direction "
+			    "(-D) packet index (-i) and data path (-f)");
+		if ((fd = open(data_path, O_RDONLY)) == -1)
+			err(1, "open %s", data_path);
+		replace_data = sshbuf_new();
+		if ((r = sshkey_load_file(fd, replace_data)) != 0)
+			errx(1, "read %s: %s", data_path, ssh_err(r));
+		close(fd);
+	}
+
+	/* Dump mode */
+	if (dump_flag) {
+		if (packet_index == -1 || direction == -1 || data_path == NULL)
+			badusage("Dump (-d) mode must specify direction "
+			    "(-D), packet index (-i) and data path (-f)");
+	}
+
+	/* Count mode needs no further flags */
+
+	do_kex_with_key(kex, key, &c2s, &s2c,
+	    direction, packet_index,
+	    dump_flag ? data_path : NULL,
+	    replace_flag ? replace_data : NULL);
+	sshkey_free(key);
+	sshbuf_free(replace_data);
+
+	if (count_flag) {
+		printf("S2C: %d\n", s2c);
+		printf("C2S: %d\n", c2s);
+	}
+
+	return 0;
+}