diff options
Diffstat (limited to 'fuzz-common.c')
| -rw-r--r-- | fuzz-common.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/fuzz-common.c b/fuzz-common.c new file mode 100644 index 0000000..f64504f --- /dev/null +++ b/fuzz-common.c @@ -0,0 +1,190 @@ +#include "includes.h" + +#include "includes.h" +#include "fuzz.h" +#include "dbutil.h" +#include "runopts.h" +#include "crypto_desc.h" +#include "session.h" +#include "dbrandom.h" +#include "bignum.h" +#include "fuzz-wrapfd.h" + +struct dropbear_fuzz_options fuzz; + +static void fuzz_dropbear_log(int UNUSED(priority), const char* format, va_list param); +static void load_fixed_hostkeys(void); + +void fuzz_common_setup(void) { + fuzz.fuzzing = 1; + fuzz.wrapfds = 1; + fuzz.do_jmp = 1; + fuzz.input = m_malloc(sizeof(buffer)); + _dropbear_log = fuzz_dropbear_log; + crypto_init(); + /* let any messages get flushed */ + setlinebuf(stdout); +} + +int fuzz_set_input(const uint8_t *Data, size_t Size) { + + fuzz.input->data = (unsigned char*)Data; + fuzz.input->size = Size; + fuzz.input->len = Size; + fuzz.input->pos = 0; + + memset(&ses, 0x0, sizeof(ses)); + memset(&svr_ses, 0x0, sizeof(svr_ses)); + wrapfd_setup(); + + fuzz_seed(); + + return DROPBEAR_SUCCESS; +} + +#if DEBUG_TRACE +static void fuzz_dropbear_log(int UNUSED(priority), const char* format, va_list param) { + if (debug_trace) { + char printbuf[1024]; + vsnprintf(printbuf, sizeof(printbuf), format, param); + fprintf(stderr, "%s\n", printbuf); + } +} +#else +static void fuzz_dropbear_log(int UNUSED(priority), const char* UNUSED(format), va_list UNUSED(param)) { + /* No print */ +} +#endif /* DEBUG_TRACE */ + +void fuzz_svr_setup(void) { + fuzz_common_setup(); + + _dropbear_exit = svr_dropbear_exit; + + char *argv[] = { + "-E", + }; + + int argc = sizeof(argv) / sizeof(*argv); + svr_getopts(argc, argv); + + /* user lookups might be slow, cache it */ + fuzz.pw_name = m_strdup("person"); + fuzz.pw_dir = m_strdup("/tmp"); + fuzz.pw_shell = m_strdup("/bin/zsh"); + fuzz.pw_passwd = m_strdup("!!zzznope"); + + load_fixed_hostkeys(); +} + +static void load_fixed_hostkeys(void) { +#include "fuzz-hostkeys.c" + + buffer *b = buf_new(3000); + enum signkey_type type; + + TRACE(("load fixed hostkeys")) + + svr_opts.hostkey = new_sign_key(); + + buf_setlen(b, 0); + buf_putbytes(b, keyr, keyr_len); + buf_setpos(b, 0); + type = DROPBEAR_SIGNKEY_RSA; + if (buf_get_priv_key(b, svr_opts.hostkey, &type) == DROPBEAR_FAILURE) { + dropbear_exit("failed fixed rsa hostkey"); + } + + buf_setlen(b, 0); + buf_putbytes(b, keyd, keyd_len); + buf_setpos(b, 0); + type = DROPBEAR_SIGNKEY_DSS; + if (buf_get_priv_key(b, svr_opts.hostkey, &type) == DROPBEAR_FAILURE) { + dropbear_exit("failed fixed dss hostkey"); + } + + buf_setlen(b, 0); + buf_putbytes(b, keye, keye_len); + buf_setpos(b, 0); + type = DROPBEAR_SIGNKEY_ECDSA_NISTP256; + if (buf_get_priv_key(b, svr_opts.hostkey, &type) == DROPBEAR_FAILURE) { + dropbear_exit("failed fixed ecdsa hostkey"); + } + + buf_free(b); +} + +void fuzz_kex_fakealgos(void) { + ses.newkeys->recv.crypt_mode = &dropbear_mode_none; +} + +void fuzz_get_socket_address(int UNUSED(fd), char **local_host, char **local_port, + char **remote_host, char **remote_port, int UNUSED(host_lookup)) { + if (local_host) { + *local_host = m_strdup("fuzzlocalhost"); + } + if (local_port) { + *local_port = m_strdup("1234"); + } + if (remote_host) { + *remote_host = m_strdup("fuzzremotehost"); + } + if (remote_port) { + *remote_port = m_strdup("9876"); + } +} + +/* cut down version of svr_send_msg_kexdh_reply() that skips slow maths. Still populates structures */ +void fuzz_fake_send_kexdh_reply(void) { + assert(!ses.dh_K); + m_mp_alloc_init_multi(&ses.dh_K, NULL); + mp_set_int(ses.dh_K, 12345678); + finish_kexhashbuf(); +} + +int fuzz_run_preauth(const uint8_t *Data, size_t Size, int skip_kexmaths) { + static int once = 0; + if (!once) { + fuzz_svr_setup(); + fuzz.skip_kexmaths = skip_kexmaths; + once = 1; + } + + if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) { + return 0; + } + + /* + get prefix. input format is + string prefix + uint32 wrapfd seed + ... to be extended later + [bytes] ssh input stream + */ + + /* be careful to avoid triggering buffer.c assertions */ + if (fuzz.input->len < 8) { + return 0; + } + size_t prefix_size = buf_getint(fuzz.input); + if (prefix_size != 4) { + return 0; + } + uint32_t wrapseed = buf_getint(fuzz.input); + wrapfd_setseed(wrapseed); + + int fakesock = 20; + wrapfd_add(fakesock, fuzz.input, PLAIN); + + m_malloc_set_epoch(1); + if (setjmp(fuzz.jmp) == 0) { + svr_session(fakesock, fakesock); + m_malloc_free_epoch(1, 0); + } else { + m_malloc_free_epoch(1, 1); + TRACE(("dropbear_exit longjmped")) + /* dropbear_exit jumped here */ + } + + return 0; +} |