1 /*
2 *
3 * honggfuzz - architecture dependent code (LINUX)
4 * -----------------------------------------
5 *
6 * Author: Robert Swiecki <swiecki@google.com>
7 *
8 * Copyright 2010-2018 by Google Inc. All Rights Reserved.
9 *
10 * Licensed under the Apache License, Version 2.0 (the "License"); you may
11 * not use this file except in compliance with the License. You may obtain
12 * a copy of the License at
13 *
14 * http://www.apache.org/licenses/LICENSE-2.0
15 *
16 * Unless required by applicable law or agreed to in writing, software
17 * distributed under the License is distributed on an "AS IS" BASIS,
18 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
19 * implied. See the License for the specific language governing
20 * permissions and limitations under the License.
21 *
22 */
23
24 #include "arch.h"
25
26 #include <ctype.h>
27 #include <dlfcn.h>
28 #include <errno.h>
29 #include <fcntl.h>
30 #include <inttypes.h>
31 #include <locale.h>
32 #include <setjmp.h>
33 #include <signal.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <sys/cdefs.h>
38 #include <sys/personality.h>
39 #include <sys/prctl.h>
40 #include <sys/syscall.h>
41 #include <sys/time.h>
42 #include <sys/types.h>
43 #include <sys/user.h>
44 #include <sys/utsname.h>
45 #include <sys/wait.h>
46 #include <time.h>
47 #include <unistd.h>
48
49 #include "fuzz.h"
50 #include "libhfcommon/common.h"
51 #include "libhfcommon/files.h"
52 #include "libhfcommon/log.h"
53 #include "libhfcommon/ns.h"
54 #include "libhfcommon/util.h"
55 #include "linux/perf.h"
56 #include "linux/trace.h"
57 #include "sanitizers.h"
58 #include "subproc.h"
59
60 static uint8_t arch_clone_stack[128 * 1024] __attribute__((aligned(__BIGGEST_ALIGNMENT__)));
61 static __thread jmp_buf env;
62
63 HF_ATTR_NO_SANITIZE_ADDRESS
64 HF_ATTR_NO_SANITIZE_MEMORY
arch_cloneFunc(void * arg HF_ATTR_UNUSED)65 static int arch_cloneFunc(void* arg HF_ATTR_UNUSED) {
66 longjmp(env, 1);
67 abort();
68 return 0;
69 }
70
71 /* Avoid problem with caching of PID/TID in glibc */
arch_clone(uintptr_t flags)72 static pid_t arch_clone(uintptr_t flags) {
73 if (flags & CLONE_VM) {
74 LOG_E("Cannot use clone(flags & CLONE_VM)");
75 return -1;
76 }
77
78 if (setjmp(env) == 0) {
79 void* stack_mid = &arch_clone_stack[sizeof(arch_clone_stack) / 2];
80 /* Parent */
81 return clone(arch_cloneFunc, stack_mid, flags, NULL, NULL, NULL);
82 }
83 /* Child */
84 return 0;
85 }
86
arch_fork(run_t * run)87 pid_t arch_fork(run_t* run) {
88 pid_t pid = run->global->linux.useClone ? arch_clone(CLONE_UNTRACED | SIGCHLD) : fork();
89 if (pid == -1) {
90 return pid;
91 }
92 if (pid == 0) {
93 logMutexReset();
94 if (prctl(PR_SET_PDEATHSIG, (unsigned long)SIGKILL, 0UL, 0UL, 0UL) == -1) {
95 PLOG_W("prctl(PR_SET_PDEATHSIG, SIGKILL)");
96 }
97 return pid;
98 }
99 return pid;
100 }
101
arch_launchChild(run_t * run)102 bool arch_launchChild(run_t* run) {
103 if ((run->global->linux.cloneFlags & CLONE_NEWNET) && (nsIfaceUp("lo") == false)) {
104 LOG_W("Cannot bring interface 'lo' up");
105 }
106
107 /*
108 * Make it attach-able by ptrace()
109 */
110 if (prctl(PR_SET_DUMPABLE, 1UL, 0UL, 0UL, 0UL) == -1) {
111 PLOG_E("prctl(PR_SET_DUMPABLE, 1)");
112 return false;
113 }
114
115 /*
116 * Kill a process which corrupts its own heap (with ABRT)
117 */
118 if (setenv("MALLOC_CHECK_", "7", 0) == -1) {
119 PLOG_E("setenv(MALLOC_CHECK_=7) failed");
120 return false;
121 }
122 if (setenv("MALLOC_PERTURB_", "85", 0) == -1) {
123 PLOG_E("setenv(MALLOC_PERTURB_=85) failed");
124 return false;
125 }
126
127 /*
128 * Disable ASLR:
129 * This might fail in Docker, as Docker blocks __NR_personality. Consequently
130 * it's just a debug warning
131 */
132 if (run->global->linux.disableRandomization &&
133 syscall(__NR_personality, ADDR_NO_RANDOMIZE) == -1) {
134 PLOG_D("personality(ADDR_NO_RANDOMIZE) failed");
135 }
136
137 #define ARGS_MAX 512
138 const char* args[ARGS_MAX + 2];
139 char argData[PATH_MAX];
140
141 char inputFile[PATH_MAX];
142 snprintf(inputFile, sizeof(inputFile), "/dev/fd/%d", run->dynamicFileCopyFd);
143
144 int x = 0;
145 for (x = 0; x < ARGS_MAX && x < run->global->exe.argc; x++) {
146 if (run->global->exe.persistent || run->global->exe.fuzzStdin) {
147 args[x] = run->global->exe.cmdline[x];
148 } else if (!strcmp(run->global->exe.cmdline[x], _HF_FILE_PLACEHOLDER)) {
149 args[x] = inputFile;
150 } else if (strstr(run->global->exe.cmdline[x], _HF_FILE_PLACEHOLDER)) {
151 const char* off = strstr(run->global->exe.cmdline[x], _HF_FILE_PLACEHOLDER);
152 snprintf(argData, sizeof(argData), "%.*s%s", (int)(off - run->global->exe.cmdline[x]),
153 run->global->exe.cmdline[x], inputFile);
154 args[x] = argData;
155 } else {
156 args[x] = run->global->exe.cmdline[x];
157 }
158 }
159 args[x++] = NULL;
160
161 LOG_D("Launching '%s' on file '%s'", args[0],
162 run->global->exe.persistent ? "PERSISTENT_MODE" : inputFile);
163
164 /* alarms persist across execve(), so disable it here */
165 alarm(0);
166
167 /* Wait for the ptrace to attach now */
168 if (kill(syscall(__NR_getpid), SIGSTOP) == -1) {
169 LOG_F("Couldn't stop itself");
170 }
171 #if defined(__NR_execveat)
172 syscall(__NR_execveat, run->global->linux.exeFd, "", args, environ, AT_EMPTY_PATH);
173 #endif /* defined__NR_execveat) */
174 execve(args[0], (char* const*)args, environ);
175 int errno_cpy = errno;
176 alarm(1);
177
178 LOG_E("execve('%s', fd=%d): %s", args[0], run->global->linux.exeFd, strerror(errno_cpy));
179
180 return false;
181 }
182
arch_attachToNewPid(run_t * run)183 static bool arch_attachToNewPid(run_t* run) {
184 if (!arch_traceAttach(run)) {
185 LOG_W("arch_traceAttach(pid=%d) failed", run->pid);
186 return false;
187 }
188
189 return true;
190 }
191
arch_prepareParentAfterFork(run_t * run)192 void arch_prepareParentAfterFork(run_t* run) {
193 /* Parent */
194 if (run->global->exe.persistent) {
195 const struct f_owner_ex fown = {
196 .type = F_OWNER_TID,
197 .pid = syscall(__NR_gettid),
198 };
199 if (fcntl(run->persistentSock, F_SETOWN_EX, &fown)) {
200 PLOG_F("fcntl(%d, F_SETOWN_EX)", run->persistentSock);
201 }
202 if (fcntl(run->persistentSock, F_SETSIG, SIGIO) == -1) {
203 PLOG_F("fcntl(%d, F_SETSIG, SIGIO)", run->persistentSock);
204 }
205 if (fcntl(run->persistentSock, F_SETFL, O_ASYNC) == -1) {
206 PLOG_F("fcntl(%d, F_SETFL, O_ASYNC)", run->persistentSock);
207 }
208 }
209
210 if (!arch_perfOpen(run)) {
211 LOG_F("Couldn't open perf event for pid=%d", (int)run->pid);
212 }
213 if (!arch_attachToNewPid(run)) {
214 LOG_F("Couldn't attach to pid=%d", (int)run->pid);
215 }
216 }
217
arch_prepareParent(run_t * run)218 void arch_prepareParent(run_t* run) {
219 if (!arch_perfEnable(run)) {
220 LOG_F("Couldn't enable perf counters for pid=%d", (int)run->pid);
221 }
222 }
223
arch_checkWait(run_t * run)224 static bool arch_checkWait(run_t* run) {
225 /* All queued wait events must be tested when SIGCHLD was delivered */
226 for (;;) {
227 int status;
228 pid_t pid = TEMP_FAILURE_RETRY(waitpid(-1, &status, __WALL | __WNOTHREAD | WNOHANG));
229 if (pid == 0) {
230 return false;
231 }
232 if (pid == -1 && errno == ECHILD) {
233 LOG_D("No more processes to track");
234 return true;
235 }
236 if (pid == -1) {
237 PLOG_F("waitpid() failed");
238 }
239
240 char statusStr[4096];
241 LOG_D("pid=%d returned with status: %s", pid,
242 subproc_StatusToStr(status, statusStr, sizeof(statusStr)));
243
244 arch_traceAnalyze(run, status, pid);
245
246 if (pid == run->pid && (WIFEXITED(status) || WIFSIGNALED(status))) {
247 if (run->global->exe.persistent) {
248 if (!fuzz_isTerminating()) {
249 LOG_W("Persistent mode: pid=%d exited with status: %s", (int)run->pid,
250 subproc_StatusToStr(status, statusStr, sizeof(statusStr)));
251 }
252 }
253 return true;
254 }
255 }
256 }
257
arch_reapChild(run_t * run)258 void arch_reapChild(run_t* run) {
259 for (;;) {
260 if (subproc_persistentModeStateMachine(run)) {
261 break;
262 }
263
264 subproc_checkTimeLimit(run);
265 subproc_checkTermination(run);
266
267 const struct timespec ts = {
268 .tv_sec = 0ULL,
269 .tv_nsec = (1000ULL * 1000ULL * 250ULL),
270 };
271 /* Return with SIGIO, SIGCHLD and with SIGUSR1 */
272 int sig = sigtimedwait(&run->global->exe.waitSigSet, NULL, &ts /* 0.25s */);
273 if (sig == -1 && (errno != EAGAIN && errno != EINTR)) {
274 PLOG_F("sigwaitinfo(SIGIO|SIGCHLD|SIGUSR1)");
275 }
276
277 if (arch_checkWait(run)) {
278 run->pid = 0;
279 break;
280 }
281 if (run->global->socketFuzzer.enabled) {
282 // Do not wait for new events
283 break;
284 }
285 }
286 if (run->global->sanitizer.enable) {
287 char crashReport[PATH_MAX];
288 snprintf(crashReport, sizeof(crashReport), "%s/%s.%d", run->global->io.workDir, kLOGPREFIX,
289 run->pid);
290 if (files_exists(crashReport)) {
291 if (run->backtrace) {
292 unlink(crashReport);
293 } else {
294 LOG_W("Un-handled ASan report due to compiler-rt internal error - retry with '%s'",
295 crashReport);
296 /* Try to parse report file */
297 arch_traceExitAnalyze(run, run->pid);
298 }
299 }
300 }
301
302 if (run->pid == 0) {
303 arch_perfClose(run);
304 }
305 arch_perfAnalyze(run);
306 }
307
arch_archInit(honggfuzz_t * hfuzz)308 bool arch_archInit(honggfuzz_t* hfuzz) {
309 /* Make %'d work */
310 setlocale(LC_NUMERIC, "en_US.UTF-8");
311
312 if (access(hfuzz->exe.cmdline[0], X_OK) == -1) {
313 PLOG_E("File '%s' doesn't seem to be executable", hfuzz->exe.cmdline[0]);
314 return false;
315 }
316 if ((hfuzz->linux.exeFd =
317 TEMP_FAILURE_RETRY(open(hfuzz->exe.cmdline[0], O_RDONLY | O_CLOEXEC))) == -1) {
318 PLOG_E("Cannot open the executable binary: %s)", hfuzz->exe.cmdline[0]);
319 return false;
320 }
321
322 for (;;) {
323 __attribute__((weak)) const char* gnu_get_libc_version(void);
324 if (!gnu_get_libc_version) {
325 LOG_W("Unknown libc implementation. Using clone() instead of fork()");
326 break;
327 }
328 const char* gversion = gnu_get_libc_version();
329 int major, minor;
330 if (sscanf(gversion, "%d.%d", &major, &minor) != 2) {
331 LOG_W("Unknown glibc version:'%s'. Using clone() instead of fork()", gversion);
332 break;
333 }
334 if ((major < 2) || (major == 2 && minor < 23)) {
335 LOG_W("Your glibc version:'%s' will most likely result in malloc()-related "
336 "deadlocks. Min. version 2.24 (Or, Ubuntu's 2.23-0ubuntu6) suggested. "
337 "See https://sourceware.org/bugzilla/show_bug.cgi?id=19431 for explanation. "
338 "Using clone() instead of fork()",
339 gversion);
340 break;
341 }
342 LOG_D("Glibc version:'%s', OK", gversion);
343 hfuzz->linux.useClone = false;
344 break;
345 }
346
347 if (hfuzz->feedback.dynFileMethod != _HF_DYNFILE_NONE) {
348 unsigned long major = 0, minor = 0;
349 char* p = NULL;
350
351 /*
352 * Check that Linux kernel is compatible
353 *
354 * Compatibility list:
355 * 1) Perf exclude_callchain_kernel requires kernel >= 3.7
356 * TODO: Runtime logic to disable it for unsupported kernels
357 * if it doesn't affect perf counters processing
358 * 2) If 'PERF_TYPE_HARDWARE' is not supported by kernel, ENOENT
359 * is returned from perf_event_open(). Unfortunately, no reliable
360 * way to detect it here. libperf exports some list functions,
361 * although small guarantees it's installed. Maybe a more targeted
362 * message at perf_event_open() error handling will help.
363 * 3) Intel's PT and new Intel BTS format require kernel >= 4.1
364 */
365 unsigned long checkMajor = 3, checkMinor = 7;
366 if ((hfuzz->feedback.dynFileMethod & _HF_DYNFILE_BTS_EDGE) ||
367 (hfuzz->feedback.dynFileMethod & _HF_DYNFILE_IPT_BLOCK)) {
368 checkMajor = 4;
369 checkMinor = 1;
370 }
371
372 struct utsname uts;
373 if (uname(&uts) == -1) {
374 PLOG_F("uname() failed");
375 return false;
376 }
377
378 p = uts.release;
379 major = strtoul(p, &p, 10);
380 if (*p++ != '.') {
381 LOG_F("Unsupported kernel version (%s)", uts.release);
382 return false;
383 }
384
385 minor = strtoul(p, &p, 10);
386 if ((major < checkMajor) || ((major == checkMajor) && (minor < checkMinor))) {
387 LOG_E("Kernel version '%s' not supporting chosen perf method", uts.release);
388 return false;
389 }
390
391 if (!arch_perfInit(hfuzz)) {
392 return false;
393 }
394 }
395 #if defined(__ANDROID__) && defined(__arm__) && defined(OPENSSL_ARMCAP_ABI)
396 /*
397 * For ARM kernels running Android API <= 21, if fuzzing target links to
398 * libcrypto (OpenSSL), OPENSSL_cpuid_setup initialization is triggering a
399 * SIGILL/ILLOPC at armv7_tick() due to "mrrc p15, #1, r0, r1, c14)" instruction.
400 * Setups using BoringSSL (API >= 22) are not affected.
401 */
402 if (setenv("OPENSSL_armcap", OPENSSL_ARMCAP_ABI, 1) == -1) {
403 PLOG_E("setenv(OPENSSL_armcap) failed");
404 return false;
405 }
406 #endif
407
408 /* Updates the important signal array based on input args */
409 arch_traceSignalsInit(hfuzz);
410
411 /*
412 * If sanitizer fuzzing enabled and SIGABRT is monitored (abort_on_error=1),
413 * increase number of major frames, since top 7-9 frames will be occupied
414 * with sanitizer runtime library & libc symbols
415 */
416 if (hfuzz->sanitizer.enable && hfuzz->cfg.monitorSIGABRT) {
417 hfuzz->linux.numMajorFrames = 14;
418 }
419
420 if (hfuzz->linux.cloneFlags && unshare(hfuzz->linux.cloneFlags) == -1) {
421 LOG_E("unshare(%tx)", hfuzz->linux.cloneFlags);
422 return false;
423 }
424
425 return true;
426 }
427
arch_archThreadInit(run_t * run)428 bool arch_archThreadInit(run_t* run) {
429 run->linux.perfMmapBuf = NULL;
430 run->linux.perfMmapAux = NULL;
431 run->linux.cpuInstrFd = -1;
432 run->linux.cpuBranchFd = -1;
433 run->linux.cpuIptBtsFd = -1;
434
435 if (prctl(PR_SET_CHILD_SUBREAPER, 1UL, 0UL, 0UL, 0UL) == -1) {
436 PLOG_W("prctl(PR_SET_CHILD_SUBREAPER, 1)");
437 }
438
439 sigset_t ss;
440 sigemptyset(&ss);
441 sigaddset(&ss, SIGUSR1);
442 if (pthread_sigmask(SIG_BLOCK, &ss, NULL) != 0) {
443 PLOG_W("Couldn't block SIGUSR1");
444 return false;
445 }
446
447 return true;
448 }
449