Mercurial > dropbear

changeset 1741:d1b279aa5ed1 fuzz

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Get client fuzzer building and starting (fails straight away)
author Matt Johnston <matt@ucc.asn.au>
date Sun, 18 Oct 2020 12:17:39 +0800
parents dfbe947bdf0d
children 6e71440b1e47
files Makefile.in cli-main.c cli-session.c fuzz-common.c fuzz-harness.c fuzz.h fuzzer-client.c session.h
diffstat 8 files changed, 138 insertions(+), 93 deletions(-) [+]
line wrap: on
line diff
--- a/Makefile.in	Thu Oct 15 22:46:24 2020 +0800
+++ b/Makefile.in	Sun Oct 18 12:17:39 2020 +0800
@@ -268,7 +268,8 @@
 ## Fuzzing targets
 
 # list of fuzz targets
-FUZZ_TARGETS=fuzzer-preauth fuzzer-pubkey fuzzer-verify fuzzer-preauth_nomaths fuzzer-kexdh fuzzer-kexecdh fuzzer-kexcurve25519
+FUZZ_TARGETS=fuzzer-preauth fuzzer-pubkey fuzzer-verify fuzzer-preauth_nomaths \
+	fuzzer-kexdh fuzzer-kexecdh fuzzer-kexcurve25519 fuzzer-client
 
 FUZZER_OPTIONS = $(addsuffix .options, $(FUZZ_TARGETS))
 
@@ -279,10 +280,7 @@
 fuzzstandalone: FUZZLIB=fuzz-harness.o
 fuzzstandalone: fuzz-harness.o fuzz-targets
 
-# exclude svr-main.o to avoid duplicate main
-svrfuzzobjs=$(subst svr-main.o, ,$(dropbearobjs))
-
-fuzz-harness.o: $(HEADERS) $(LIBTOM_DEPS) Makefile $(svrfuzzobjs) fuzz-common.o
+fuzz-harness.o: $(HEADERS) $(LIBTOM_DEPS) Makefile $(allobjs) fuzz-common.o
 
 # build all the fuzzers. This will require fail to link unless built with
 # make fuzz-targets FUZZLIB=-lFuzzer.a 
@@ -290,25 +288,28 @@
 fuzz-targets: $(FUZZ_TARGETS) $(FUZZER_OPTIONS)
 
 fuzzer-preauth: fuzzer-preauth.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-preauth_nomaths: fuzzer-preauth_nomaths.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-pubkey: fuzzer-pubkey.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-verify: fuzzer-verify.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-kexdh: fuzzer-kexdh.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-kexecdh: fuzzer-kexecdh.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-kexcurve25519: fuzzer-kexcurve25519.o fuzz-harness.o
-	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(svrfuzzobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
+
+fuzzer-client: fuzzer-client.o fuzz-harness.o
+	$(CXX) $(CXXFLAGS) [email protected] $(LDFLAGS) $(allobjs) -o $@$(EXEEXT) $(LIBTOM_LIBS) $(LIBS) $(FUZZLIB) @CRYPTLIB@
 
 fuzzer-%.options: Makefile
 	echo "[libfuzzer]"               > $@
--- a/cli-main.c	Thu Oct 15 22:46:24 2020 +0800
+++ b/cli-main.c	Sun Oct 18 12:17:39 2020 +0800
@@ -31,9 +31,7 @@
 #include "dbrandom.h"
 #include "crypto_desc.h"
 #include "netio.h"
-
-static void cli_dropbear_exit(int exitcode, const char* format, va_list param) ATTRIB_NORETURN;
-static void cli_dropbear_log(int priority, const char* format, va_list param);
+#include "fuzz.h"
 
 #if DROPBEAR_CLI_PROXYCMD
 static void cli_proxy_cmd(int *sock_in, int *sock_out, pid_t *pid_out);
@@ -98,58 +96,6 @@
 }
 #endif /* DBMULTI stuff */
 
-static void cli_dropbear_exit(int exitcode, const char* format, va_list param) {
-	char exitmsg[150];
-	char fullmsg[300];
-
-	/* Note that exit message must be rendered before session cleanup */
-
-	/* Render the formatted exit message */
-	vsnprintf(exitmsg, sizeof(exitmsg), format, param);
-	TRACE(("Exited, cleaning up: %s", exitmsg))
-
-	/* Add the prefix depending on session/auth state */
-	if (!ses.init_done) {
-		snprintf(fullmsg, sizeof(fullmsg), "Exited: %s", exitmsg);
-	} else {
-		snprintf(fullmsg, sizeof(fullmsg), 
-				"Connection to %s@%s:%s exited: %s", 
-				cli_opts.username, cli_opts.remotehost, 
-				cli_opts.remoteport, exitmsg);
-	}
-
-	/* Do the cleanup first, since then the terminal will be reset */
-	session_cleanup();
-	/* Avoid printing onwards from terminal cruft */
-	fprintf(stderr, "\n");
-
-	dropbear_log(LOG_INFO, "%s", fullmsg);
-	exit(exitcode);
-}
-
-static void cli_dropbear_log(int priority,
-		const char* format, va_list param) {
-
-	char printbuf[1024];
-	const char *name;
-
-	name = cli_opts.progname;
-	if (!name) {
-		name = "dbclient";
-	}
-
-	vsnprintf(printbuf, sizeof(printbuf), format, param);
-
-#ifndef DISABLE_SYSLOG
-	if (opts.usingsyslog) {
-		syslog(priority, "%s", printbuf);
-	}
-#endif
-
-	fprintf(stderr, "%s: %s\n", name, printbuf);
-	fflush(stderr);
-}
-
 static void exec_proxy_cmd(const void *user_data_cmd) {
 	const char *cmd = user_data_cmd;
 	char *usershell;
@@ -199,4 +145,5 @@
 	kill_proxy_command();
 	_exit(1);
 }
+
 #endif /* DROPBEAR_CLI_PROXYCMD */
--- a/cli-session.c	Thu Oct 15 22:46:24 2020 +0800
+++ b/cli-session.c	Sun Oct 18 12:17:39 2020 +0800
@@ -407,3 +407,62 @@
 	/* Send a proper rejection */
 	send_msg_request_failure();
 }
+
+void cli_dropbear_exit(int exitcode, const char* format, va_list param) {
+	char exitmsg[150];
+	char fullmsg[300];
+
+	/* Note that exit message must be rendered before session cleanup */
+
+	/* Render the formatted exit message */
+	vsnprintf(exitmsg, sizeof(exitmsg), format, param);
+	TRACE(("Exited, cleaning up: %s", exitmsg))
+
+	/* Add the prefix depending on session/auth state */
+	if (!ses.init_done) {
+		snprintf(fullmsg, sizeof(fullmsg), "Exited: %s", exitmsg);
+	} else {
+		snprintf(fullmsg, sizeof(fullmsg), 
+				"Connection to %s@%s:%s exited: %s", 
+				cli_opts.username, cli_opts.remotehost, 
+				cli_opts.remoteport, exitmsg);
+	}
+
+	/* Do the cleanup first, since then the terminal will be reset */
+	session_cleanup();
+	/* Avoid printing onwards from terminal cruft */
+	fprintf(stderr, "\n");
+
+	dropbear_log(LOG_INFO, "%s", fullmsg);
+
+#if DROPBEAR_FUZZ
+    if (fuzz.do_jmp) {
+        longjmp(fuzz.jmp, 1);
+    }
+#endif
+
+	exit(exitcode);
+}
+
+void cli_dropbear_log(int priority, const char* format, va_list param) {
+
+	char printbuf[1024];
+	const char *name;
+
+	name = cli_opts.progname;
+	if (!name) {
+		name = "dbclient";
+	}
+
+	vsnprintf(printbuf, sizeof(printbuf), format, param);
+
+#ifndef DISABLE_SYSLOG
+	if (opts.usingsyslog) {
+		syslog(priority, "%s", printbuf);
+	}
+#endif
+
+	fprintf(stderr, "%s: %s\n", name, printbuf);
+	fflush(stderr);
+}
+
--- a/fuzz-common.c	Thu Oct 15 22:46:24 2020 +0800
+++ b/fuzz-common.c	Sun Oct 18 12:17:39 2020 +0800
@@ -16,6 +16,7 @@
 static void load_fixed_hostkeys(void);
 
 void fuzz_common_setup(void) {
+	disallow_core();
     fuzz.fuzzing = 1;
     fuzz.wrapfds = 1;
     fuzz.do_jmp = 1;
@@ -69,37 +70,23 @@
     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();
 }
 
-#if 0
 void fuzz_cli_setup(void) {
     fuzz_common_setup();
     
-    _dropbear_exit = cli_dropbear_exit;
+	_dropbear_exit = cli_dropbear_exit;
+	_dropbear_log = cli_dropbear_log;
 
     char *argv[] = { 
-        "-E", 
+		"-y",
+        "localhost",
     };
 
     int argc = sizeof(argv) / sizeof(*argv);
     cli_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();
 }
-#endif
 
 static void load_fixed_hostkeys(void) {
 #include "fuzz-hostkeys.c"   
@@ -198,7 +185,7 @@
     }
 
     /*
-      get prefix. input format is
+      get prefix, allowing for future extensibility. input format is
       string prefix
           uint32 wrapfd seed
           ... to be extended later
@@ -231,6 +218,52 @@
     return 0;
 }
 
+int fuzz_run_client(const uint8_t *Data, size_t Size, int skip_kexmaths) {
+    static int once = 0;
+    if (!once) {
+        fuzz_cli_setup();
+        fuzz.skip_kexmaths = skip_kexmaths;
+        once = 1;
+    }
+
+    if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) {
+        return 0;
+    }
+
+    /*
+      get prefix, allowing for future extensibility. 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 = wrapfd_new();
+
+    m_malloc_set_epoch(1);
+    if (setjmp(fuzz.jmp) == 0) {
+        cli_session(fakesock, fakesock, NULL, 0);
+        m_malloc_free_epoch(1, 0);
+    } else {
+        m_malloc_free_epoch(1, 1);
+        TRACE(("dropbear_exit longjmped"))
+        /* dropbear_exit jumped here */
+    }
+
+    return 0;
+}
+
 const void* fuzz_get_algo(const algo_type *algos, const char* name) {
     const algo_type *t;
     for (t = algos; t->name; t++) {
--- a/fuzz-harness.c	Thu Oct 15 22:46:24 2020 +0800
+++ b/fuzz-harness.c	Sun Oct 18 12:17:39 2020 +0800
@@ -29,6 +29,7 @@
         buf_readfile(input, fn);
         buf_setpos(input, 0);
 
+		/* Run twice to catch problems with statefulness */
         fuzz.wrapfds = old_fuzz_wrapfds;
         printf("Running %s once \n", fn);
         LLVMFuzzerTestOneInput(input->data, input->len);
--- a/fuzz.h	Thu Oct 15 22:46:24 2020 +0800
+++ b/fuzz.h	Sun Oct 18 12:17:39 2020 +0800
@@ -13,6 +13,7 @@
 // once per process
 void fuzz_common_setup(void);
 void fuzz_svr_setup(void);
+void fuzz_cli_setup(void);
 
 // must be called once per fuzz iteration. 
 // returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE
@@ -28,6 +29,8 @@
         const unsigned char* keyblob, unsigned int keybloblen);
 extern const char * const * fuzz_signkey_names;
 void fuzz_seed(void);
+
+// helpers
 void fuzz_get_socket_address(int fd, char **local_host, char **local_port,
                         char **remote_host, char **remote_port, int host_lookup);
 void fuzz_fake_send_kexdh_reply(void);
@@ -57,13 +60,6 @@
     // dropbear_exit() jumps back
     int do_jmp;
     sigjmp_buf jmp;
-
-    uid_t pw_uid;
-    gid_t pw_gid;
-    char* pw_name;
-    char* pw_dir;
-    char* pw_shell;
-    char* pw_passwd;
 };
 
 extern struct dropbear_fuzz_options fuzz;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/fuzzer-client.c	Sun Oct 18 12:17:39 2020 +0800
@@ -0,0 +1,6 @@
+#include "fuzz.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+	return fuzz_run_client(Data, Size, 0);
+}
+
--- a/session.h	Thu Oct 15 22:46:24 2020 +0800
+++ b/session.h	Sun Oct 18 12:17:39 2020 +0800
@@ -64,6 +64,8 @@
 /* Client */
 void cli_session(int sock_in, int sock_out, struct dropbear_progress_connection *progress, pid_t proxy_cmd_pid) ATTRIB_NORETURN;
 void cli_connected(int result, int sock, void* userdata, const char *errstring);
+void cli_dropbear_exit(int exitcode, const char* format, va_list param) ATTRIB_NORETURN;
+void cli_dropbear_log(int priority, const char* format, va_list param);
 void cleantext(char* dirtytext);
 void kill_proxy_command(void);