upstream commit

add KEX fuzzer harness; ok deraadt@

Upstream-Regress-ID: 3df5242d30551b12b828aa9ba4a4cec0846be8d1

4 files changed, 513 insertions, 0 deletions

diff --git a/regress/misc/Makefile b/regress/misc/Makefile
new file mode 100644
index 000000000..14c0c279f
--- /dev/null
+++ b/regress/misc/Makefile
@@ -0,0 +1,3 @@
+SUBDIR=         kexfuzz
+
+.include <bsd.subdir.mk>
diff --git a/regress/misc/kexfuzz/Makefile b/regress/misc/kexfuzz/Makefile
new file mode 100644
index 000000000..3018b632f
--- /dev/null
+++ b/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>
+
diff --git a/regress/misc/kexfuzz/README b/regress/misc/kexfuzz/README
new file mode 100644
index 000000000..8b215b5bf
--- /dev/null
+++ b/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.
+
diff --git a/regress/misc/kexfuzz/kexfuzz.c b/regress/misc/kexfuzz/kexfuzz.c
new file mode 100644
index 000000000..d57a117ac
--- /dev/null
+++ b/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;
+}