Merge pull request #1965 from CodeLinaro/stateful

replay mode support

.gitignore

@@ -103,6 +103,10 @@ utils/optimin/build
 utils/optimin/optimin
 utils/persistent_mode/persistent_demo
 utils/persistent_mode/persistent_demo_new
+utils/persistent_mode/persistent_demo_new_compat
 utils/persistent_mode/test-instr
+utils/replay_record/persistent_demo_replay
+utils/replay_record/persistent_demo_replay_compat
+utils/replay_record/persistent_demo_replay_argparse
 utils/plot_ui/afl-plot-ui
 vuln_prog

include/afl-fuzz.h

@@ -124,6 +124,10 @@
   #define CASE_PREFIX "id_"
 #endif                                                    /* ^!SIMPLE_FILES */
 
+#ifdef AFL_PERSISTENT_RECORD
+  #define RECORD_PREFIX "RECORD:"
+#endif
+
 #define STAGE_BUF_SIZE (64)  /* usable size for stage name buf in afl_state */
 
 // Little helper to access the ptr to afl->##name_buf - for use in afl_realloc.

include/afl-persistent-replay.h

@@ -0,0 +1,131 @@
+#ifndef _HAVE_PERSISTENT_REPLAY_H
+#define _HAVE_PERSISTENT_REPLAY_H
+
+#include <dirent.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <malloc.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#ifndef PATH_MAX
+  #define PATH_MAX 4096
+#endif
+
+static unsigned short int is_replay_record;
+static unsigned int       replay_record;
+static unsigned int       replay_record_cnt;
+static char               replay_record_path[PATH_MAX];
+static char              *replay_record_dir;
+static struct dirent    **record_list;
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+static char **record_arg = NULL;
+#endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+
+static int select_files(const struct dirent *dirbuf) {
+
+  char fn[PATH_MAX];
+
+  if (dirbuf->d_name[0] == '.') {
+
+    return 0;
+
+  } else {
+
+    snprintf(fn, sizeof(fn), "RECORD:%06u", replay_record);
+    return !!strstr(dirbuf->d_name, fn);
+
+  }
+
+}
+
+static int compare_files(const struct dirent **da, const struct dirent **db) {
+
+  unsigned int c1 = 0, c2 = 0;
+
+  sscanf((*da)->d_name, "RECORD:%*u,cnt:%06u", &c1);
+  sscanf((*db)->d_name, "RECORD:%*u,cnt:%06u", &c2);
+
+  return c1 - c2;
+
+}
+
+__attribute__((destructor)) static void __afl_record_replay_destroy(void) {
+
+  for (int i = 0; i < replay_record_cnt; i++) {
+
+    free(record_list[i]);
+
+  }
+
+  free(record_list);
+
+}
+
+__attribute__((constructor)) static void __afl_record_replay_init(
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+    int argc, char **argv
+#endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+) {
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+  char **argp;
+#endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+
+  struct stat sb;
+
+  /* caveat: if harness uses @@ and we don't pass it, it will regardless loop
+   * the number of iterations defined for AFL_LOOP (on the same file)*/
+  if (!(is_replay_record = !!getenv("AFL_PERSISTENT_REPLAY"))) {
+
+    // printf("[warning] AFL_PERSISTENT_REPLAY not set.\n");
+    return;
+
+  }
+
+  replay_record = atoi(getenv("AFL_PERSISTENT_REPLAY"));
+  replay_record_dir = getenv("AFL_PERSISTENT_DIR");
+
+  if (!(stat(replay_record_dir, &sb) == 0 && S_ISDIR(sb.st_mode))) {
+
+    fprintf(stderr, "[error] Can't find the requested record directory!\n");
+    is_replay_record = 0;
+    return;
+
+  }
+
+  replay_record_cnt = scandir(replay_record_dir ? replay_record_dir : "./",
+                              &record_list, select_files, compare_files);
+
+  if (!replay_record_cnt) {
+
+    fprintf(stderr, "[error] Can't find the requested record!\n");
+    is_replay_record = 0;
+
+  }
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+  argp = argv;
+  while (*argp) {
+
+    if (!strcmp(*argp, "@@")) {
+
+      record_arg = argp;
+      *record_arg = replay_record_path;
+      break;
+
+    }
+
+    ++argp;
+
+  }
+
+#endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+
+}
+
+#endif  // _HAVE_PERSISTENT_REPLAY_H
+

include/afl-record-compat.h

@@ -0,0 +1,67 @@
+#ifndef _HAVE_AFL_COMPAT_H
+#define _HAVE_AFL_COMPAT_H
+
+#include <afl-persistent-replay.h>
+
+#define FUZZ_BUF_SIZE 1024000
+
+// extern ssize_t read(int fildes, void *buf, size_t nbyte);
+
+// extern int __afl_persistent_loop(unsigned int max_cnt);
+// extern unsigned char fuzz_buf[];
+
+#ifndef __AFL_HAVE_MANUAL_CONTROL
+  #define __AFL_HAVE_MANUAL_CONTROL
+#endif
+
+#define __AFL_FUZZ_TESTCASE_LEN (read(0, fuzz_buf, FUZZ_BUF_SIZE))
+#define __AFL_FUZZ_TESTCASE_BUF fuzz_buf
+#define __AFL_FUZZ_INIT() void sync(void);
+#define __AFL_INIT() sync()
+#define __AFL_LOOP(x) __afl_persistent_loop(x)
+
+unsigned char fuzz_buf[FUZZ_BUF_SIZE];
+
+int __afl_persistent_loop(unsigned int max_cnt) {
+
+  static unsigned int       cycle_cnt = 1;
+  static unsigned short int inited = 0;
+  char                      tcase[PATH_MAX];
+
+  if (is_replay_record) {
+
+    if (!inited) {
+
+      cycle_cnt = replay_record_cnt;
+      inited = 1;
+
+    }
+
+    snprintf(tcase, PATH_MAX, "%s/%s",
+             replay_record_dir ? replay_record_dir : "./",
+             record_list[replay_record_cnt - cycle_cnt]->d_name);
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+    if (record_arg) {
+
+      *record_arg = tcase;
+
+    } else
+
+#endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+    {
+
+      int fd = open(tcase, O_RDONLY);
+      dup2(fd, 0);
+      close(fd);
+
+    }
+
+  }
+
+  return --cycle_cnt;
+
+}
+
+#endif  // _HAVE_AFL_COMPAT_H
+

include/config.h

@@ -97,6 +97,11 @@
 
 // #define AFL_PERSISTENT_RECORD
 
+/* Adds support in compiler-rt to replay persistent records in @@-style
+ * harnesses */
+
+//  #define AFL_PERSISTENT_REPLAY_ARGPARSE
+
 /* console output colors: There are three ways to configure its behavior
  * 1. default: colored outputs fixed on: defined USE_COLOR && defined
  * ALWAYS_COLORED The env var. AFL_NO_COLOR will have no effect

instrumentation/README.persistent_mode.md

@@ -195,4 +195,34 @@ Then as first line after the `__AFL_LOOP` while loop:
   int len = __AFL_FUZZ_TESTCASE_LEN;
 ```
 
-And that is all!
+And that is all!
+
+## 6) Persistent record, and replay
+
+If your software under test requires keeping a state between persistent loop iterations (i.e., a stateful network stack), you can use the `AFL_PERSISTENT_RECORD` variable as described in the [environment variables documentation](../docs/env_variables.md).
+
+When `AFL_PERSISTENT_RECORD` is enabled, replay functionality is also included in the compiler-rt library. To replay a specific record, assign the record number to the AFL_PERSISTENT_REPLAY environment variable (i.e., `RECORD:XXXXX`` -> `AFL_PERSISTENT_REPLAY=XXXXX`), and run the test binary as you would normally do.
+The directory where the record files live can be specified via the `AFL_PERSISTENT_DIR` environment varilable, otherwise by default it will be considered the current directory (`./`).
+
+If your harness reads the input files from arguments using the special `@@` argument you will need to include support by enabling `AFL_PERSISTENT_ARGPARSE` in  `config.h`.
+
+In order to offer transparent support to harnesses using the `@@` command line argument, arguments are parsed by the `__afl_record_replay_init` init function. Since not all systems support passing arguments to initializers, this functionality is disabled by default, it's recommendable to use the `__AFL_FUZZ_TESTCASE_BUF/__AFL_FUZZ_TESTCASE_LEN` shared memory mechanism instead.
+
+## 7) Drop-in persistent loop replay replacement
+
+To use the replay functionality without having to use `afl-cc`, include the [include/record_compat.h](../include/afl-record_compat.h) header file. Together with the [include/afl-persistent-replay.h](../include/afl-persistent-replay.h) header included in it, `afl-record-compat.h` provides a drop-in replacement for the persistent loop mechanism.
+
+```c
+#ifndef __AFL_FUZZ_TESTCASE_LEN
+  // #define AFL_PERSISTENT_REPLAY_ARGPARSE
+  #include "afl-record-compat.h"
+#endif
+
+__AFL_FUZZ_INIT();
+```
+
+A simple example is provided in [persistent_demo_replay.c](../utils/replay_record/persistent_demo_replay.c).
+
+Be aware that the [afl-record-compat.h](../include/afl-record-compat.h) header should only be included in a single compilation unit, or you will end up with clobbered functions and variables.
+
+If you need a cleaner solution, you'll have to move the functions and variables defined in [include/record_compat.h](../include/afl-record-compat.h) and [include/afl-persistent-replay.h](../include/afl-persistent-replay.h) in a C file, and add the relevant declarations to a header file. After including the new header file, the compilation unit resulting from compiling the C file can then be linked with your program.

instrumentation/afl-compiler-rt.o.c

@@ -87,6 +87,10 @@ __attribute__((weak)) void __sanitizer_symbolize_pc(void *, const char *fmt,
 #include <sys/mman.h>
 #include <fcntl.h>
 
+#ifdef AFL_PERSISTENT_RECORD
+  #include "afl-persistent-replay.h"
+#endif
+
 /* Globals needed by the injected instrumentation. The __afl_area_initial region
    is used for instrumentation output before __afl_map_shm() has a chance to
    run. It will end up as .comm, so it shouldn't be too wasteful. */
@@ -1354,6 +1358,10 @@ int __afl_persistent_loop(unsigned int max_cnt) {
   static u8  first_pass = 1;
   static u32 cycle_cnt;
 
+#ifdef AFL_PERSISTENT_RECORD
+  char tcase[PATH_MAX];
+#endif
+
   if (first_pass) {
 
     /* Make sure that every iteration of __AFL_LOOP() starts with a clean slate.
@@ -1365,14 +1373,59 @@ int __afl_persistent_loop(unsigned int max_cnt) {
     __afl_area_ptr[0] = 1;
     memset(__afl_prev_loc, 0, NGRAM_SIZE_MAX * sizeof(PREV_LOC_T));
 
-    cycle_cnt = max_cnt;
     first_pass = 0;
     __afl_selective_coverage_temp = 1;
 
+#ifdef AFL_PERSISTENT_RECORD
+    if (unlikely(is_replay_record)) {
+
+      cycle_cnt = replay_record_cnt;
+      goto persistent_record;
+
+    } else
+
+#endif
+    {
+
+      cycle_cnt = max_cnt;
+
+    }
+
     return 1;
 
   } else if (--cycle_cnt) {
 
+#ifdef AFL_PERSISTENT_RECORD
+    if (unlikely(is_replay_record)) {
+
+    persistent_record:
+
+      snprintf(tcase, PATH_MAX, "%s/%s",
+               replay_record_dir ? replay_record_dir : "./",
+               record_list[replay_record_cnt - cycle_cnt]->d_name);
+
+  #ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+      if (unlikely(record_arg)) {
+
+        *record_arg = tcase;
+
+      } else
+
+  #endif  // AFL_PERSISTENT_REPLAY_ARGPARSE
+      {
+
+        int fd = open(tcase, O_RDONLY);
+        dup2(fd, 0);
+        close(fd);
+
+      }
+
+      return 1;
+
+    }
+
+#endif
+
     raise(SIGSTOP);
 
     __afl_area_ptr[0] = 1;

src/afl-forkserver.c

@@ -1599,6 +1599,11 @@ afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout,
   u32 exec_ms;
   u32 write_value = fsrv->last_run_timed_out;
 
+#ifdef AFL_PERSISTENT_RECORD
+  fsrv_run_result_t retval = FSRV_RUN_OK;
+  char             *persistent_out_fmt;
+#endif
+
 #ifdef __linux__
   if (fsrv->nyx_mode) {
 
@@ -1798,6 +1803,18 @@ afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout,
   if (unlikely(fsrv->last_run_timed_out)) {
 
     fsrv->last_kill_signal = fsrv->child_kill_signal;
+
+#ifdef AFL_PERSISTENT_RECORD
+    if (unlikely(fsrv->persistent_record)) {
+
+      retval = FSRV_RUN_TMOUT;
+      persistent_out_fmt = "%s/hangs/RECORD:%06u,cnt:%06u";
+      goto store_persistent_record;
+
+    }
+
+#endif
+
     return FSRV_RUN_TMOUT;
 
   }
@@ -1819,42 +1836,21 @@ afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout,
           (fsrv->uses_crash_exitcode &&
            WEXITSTATUS(fsrv->child_status) == fsrv->crash_exitcode))) {
 
+    /* For a proper crash, set last_kill_signal to WTERMSIG, else set it to 0 */
+    fsrv->last_kill_signal =
+        WIFSIGNALED(fsrv->child_status) ? WTERMSIG(fsrv->child_status) : 0;
+
 #ifdef AFL_PERSISTENT_RECORD
     if (unlikely(fsrv->persistent_record)) {
 
-      char fn[PATH_MAX];
-      u32  i, writecnt = 0;
-      for (i = 0; i < fsrv->persistent_record; ++i) {
-
-        u32 entry = (i + fsrv->persistent_record_idx) % fsrv->persistent_record;
-        u8 *data = fsrv->persistent_record_data[entry];
-        u32 len = fsrv->persistent_record_len[entry];
-        if (likely(len && data)) {
-
-          snprintf(fn, sizeof(fn), "%s/RECORD:%06u,cnt:%06u",
-                   fsrv->persistent_record_dir, fsrv->persistent_record_cnt,
-                   writecnt++);
-          int fd = open(fn, O_CREAT | O_TRUNC | O_WRONLY, 0644);
-          if (fd >= 0) {
-
-            ck_write(fd, data, len, fn);
-            close(fd);
-
-          }
-
-        }
-
-      }
-
-      ++fsrv->persistent_record_cnt;
+      retval = FSRV_RUN_CRASH;
+      persistent_out_fmt = "%s/crashes/RECORD:%06u,cnt:%06u";
+      goto store_persistent_record;
 
     }
 
 #endif
 
-    /* For a proper crash, set last_kill_signal to WTERMSIG, else set it to 0 */
-    fsrv->last_kill_signal =
-        WIFSIGNALED(fsrv->child_status) ? WTERMSIG(fsrv->child_status) : 0;
     return FSRV_RUN_CRASH;
 
   }
@@ -1862,6 +1858,40 @@ afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout,
   /* success :) */
   return FSRV_RUN_OK;
 
+#ifdef AFL_PERSISTENT_RECORD
+store_persistent_record: {
+
+  char fn[PATH_MAX];
+  u32  i, writecnt = 0;
+  for (i = 0; i < fsrv->persistent_record; ++i) {
+
+    u32 entry = (i + fsrv->persistent_record_idx) % fsrv->persistent_record;
+    u8 *data = fsrv->persistent_record_data[entry];
+    u32 len = fsrv->persistent_record_len[entry];
+    if (likely(len && data)) {
+
+      snprintf(fn, sizeof(fn), persistent_out_fmt, fsrv->persistent_record_dir,
+               fsrv->persistent_record_cnt, writecnt++);
+      int fd = open(fn, O_CREAT | O_TRUNC | O_WRONLY, 0644);
+      if (fd >= 0) {
+
+        ck_write(fd, data, len, fn);
+        close(fd);
+
+      }
+
+    }
+
+  }
+
+  ++fsrv->persistent_record_cnt;
+
+  return retval;
+
+}
+
+#endif
+
 }
 
 void afl_fsrv_killall() {

src/afl-fuzz-init.c

@@ -1921,6 +1921,9 @@ static void handle_existing_out_dir(afl_state_t *afl) {
 
   }
 
+#ifdef AFL_PERSISTENT_RECORD
+  delete_files(fn, RECORD_PREFIX);
+#endif
   if (delete_files(fn, CASE_PREFIX)) { goto dir_cleanup_failed; }
   ck_free(fn);
 
@@ -1953,6 +1956,9 @@ static void handle_existing_out_dir(afl_state_t *afl) {
 
   }
 
+#ifdef AFL_PERSISTENT_RECORD
+  delete_files(fn, RECORD_PREFIX);
+#endif
   if (delete_files(fn, CASE_PREFIX)) { goto dir_cleanup_failed; }
   ck_free(fn);
 

src/afl-fuzz.c

@@ -2182,7 +2182,7 @@ int main(int argc, char **argv_orig, char **envp) {
 
     }
 
-    afl->fsrv.persistent_record_dir = alloc_printf("%s/crashes", afl->out_dir);
+    afl->fsrv.persistent_record_dir = alloc_printf("%s", afl->out_dir);
 
   }
 

utils/persistent_mode/Makefile

@@ -7,4 +7,4 @@ document:
 	AFL_DONT_OPTIMIZE=1 ../../afl-clang-fast -D_AFL_DOCUMENT_MUTATIONS -o test-instr test-instr.c
 
 clean:
-	rm -f persistent_demo persistent_demo_new test-instr
+	rm -f persistent_demo persistent_demo_new persistent_demo_new_compat test-instr

utils/replay_record/Makefile

@@ -0,0 +1,8 @@
+all:
+	test `grep '//[\s\t ]*#define[\s\t ]*AFL_PERSISTENT_RECORD' ../../include/config.h | wc -l` -eq 0 || (echo "AFL_PERSISTENT_RECORD must be enabled in config.h"; exit 1)
+	../../afl-clang-fast -o persistent_demo_replay persistent_demo_replay.c
+	${CC} -I ../../include -o persistent_demo_replay_compat persistent_demo_replay.c
+	${CC} -g -I ../../include -DAFL_PERSISTENT_REPLAY_ARGPARSE -o persistent_demo_replay_argparse persistent_demo_replay.c
+
+clean:
+	rm -f persistent_demo_replay persistent_demo_replay_argparse persistent_demo_replay_compat

utils/replay_record/README.md

@@ -0,0 +1,10 @@
+# AFL++ persistent record replay
+
+This persistent record replay demo showcases the `AFL_PERSISTENT_RECORD` replay functionality.
+
+The [Makefile](Makefile) will produce three binaries:
+  + persistent_demo_replay: uses afl-cc and makes use of the replay functionality included in the compiler runtime library
+  + persistent_demo_replay_compat: uses the [afl-record-compat.h](../../include/afl-record-compat.h) compatibility header to compile the same example without `afl-cc` 
+  + persistent_demo_replay_argparse: makes use of `afl-record-compat.h`, and the Makefile defines `AFL_PERSISTENT_REPLAY_ARGPARSE` to test the replay functionality but parses the input file via a command-line argument (`@@`-style harness).
+
+For more information see [README.persistent_mode.md](../../instrumentation/README.persistent_mode.md).

utils/replay_record/persistent_demo_replay.c

@@ -0,0 +1,148 @@
+/*
+   american fuzzy lop++ - persistent mode example
+   --------------------------------------------
+
+   Originally written by Michal Zalewski
+
+   Copyright 2015 Google Inc. All rights reserved.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at:
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+   This file demonstrates the high-performance "persistent mode" that may be
+   suitable for fuzzing certain fast and well-behaved libraries, provided that
+   they are stateless or that their internal state can be easily reset
+   across runs.
+
+   To make this work, the library and this shim need to be compiled in LLVM
+   mode using afl-clang-fast (other compiler wrappers will *not* work).
+
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+#include <limits.h>
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+  #include <sys/stat.h>
+  #include <fcntl.h>
+#endif
+
+/* this lets the source compile without afl-clang-fast/lto */
+#ifndef __AFL_FUZZ_TESTCASE_LEN
+  #include "afl-record-compat.h"
+#endif
+
+__AFL_FUZZ_INIT();
+
+/* Main entry point. */
+
+/* To ensure checks are not optimized out it is recommended to disable
+   code optimization for the fuzzer harness main() */
+#pragma clang optimize off
+#pragma GCC            optimize("O0")
+
+int main(int argc, char **argv) {
+
+  ssize_t        len;                        /* how much input did we read? */
+  unsigned char *buf;                        /* test case buffer pointer    */
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+  int fd;
+
+  if (argc < 2) { printf("Need an input file!"); }
+#endif
+
+  /* The number passed to __AFL_LOOP() controls the maximum number of
+     iterations before the loop exits and the program is allowed to
+     terminate normally. This limits the impact of accidental memory leaks
+     and similar hiccups. */
+
+  __AFL_INIT();
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+  buf = malloc(1000);
+#else
+  buf = __AFL_FUZZ_TESTCASE_BUF;  // this must be assigned before __AFL_LOOP!
+#endif
+
+  while (__AFL_LOOP(UINT_MAX)) {  // increase if you have good stability
+
+#ifdef AFL_PERSISTENT_REPLAY_ARGPARSE
+    fd = open(argv[1], O_RDONLY);
+    len = read(fd, buf, 1000);
+    close(fd);
+#else
+    len = __AFL_FUZZ_TESTCASE_LEN;  // do not use the macro directly in a call!
+#endif
+
+    // fprintf(stderr, "input: %zd \"%s\"\n", len, buf);
+
+    /* do we have enough data? */
+    if (len < 8) continue;
+
+    if (strcmp((char *)buf, "thisisateststring") == 0) printf("teststring\n");
+
+    if (buf[0] == 'f') {
+
+      printf("one\n");
+      if (buf[1] == 'o') {
+
+        printf("two\n");
+        if (buf[2] == 'o') {
+
+          printf("three\n");
+          if (buf[3] == '!') {
+
+            printf("four\n");
+            if (buf[4] == '!') {
+
+              printf("five\n");
+              if (buf[5] == '!') {
+
+                printf("six\n");
+                abort();
+
+              } else {
+
+                if (buf[5] == 'O') {
+
+                  // hang
+                  while (1) {
+
+                    continue;
+
+                  };
+
+                }
+
+              }
+
+            }
+
+          }
+
+        }
+
+      }
+
+    }
+
+    /*** END PLACEHOLDER CODE ***/
+
+  }
+
+  /* Once the loop is exited, terminate normally - AFL will restart the process
+     when this happens, with a clean slate when it comes to allocated memory,
+     leftover file descriptors, etc. */
+
+  return 0;
+
+}
+