Support for AFL_FRIDA_PERSISTENT_RET (#941)

Co-authored-by: Your Name <you@example.com>

frida_mode/GNUmakefile

@@ -36,6 +36,10 @@ else
 CFLAGS+=-Wno-pointer-arith
 endif
 
+ifdef FRIDA_DEBUG
+CFLAGS += -DFRIDA_DEBUG
+endif
+
 FRIDA_BUILD_DIR:=$(BUILD_DIR)frida/
 FRIDA_TRACE:=$(BUILD_DIR)afl-frida-trace.so
 FRIDA_TRACE_EMBEDDED:=$(BUILD_DIR)afl-frida-trace-embedded
@@ -94,9 +98,6 @@ AFL_COMPILER_RT_OBJ:=$(OBJ_DIR)afl-compiler-rt.o
 
 all: $(FRIDA_TRACE)
 
-32:
-	CFLAGS="-m32" LDFLAGS="-m32" ARCH="x86" make all
-
 32:
 	CFLAGS="-m32" LDFLAGS="-m32" ARCH="x86" make all
 

frida_mode/include/persistent.h

@@ -18,6 +18,9 @@ extern unsigned char *__afl_fuzz_ptr;
 
 extern guint64                persistent_start;
 extern guint64                persistent_count;
+extern guint64                persistent_ret;
+extern guint64                persistent_ret_offset;
+extern gboolean               persistent_debug;
 extern afl_persistent_hook_fn hook;
 
 void persistent_init(void);
@@ -26,6 +29,7 @@ void persistent_init(void);
 gboolean persistent_is_supported(void);
 
 void persistent_prologue(GumStalkerOutput *output);
+void persistent_epilogue(GumStalkerOutput *output);
 
 #endif
 

frida_mode/src/instrument/instrument.c

@@ -85,6 +85,7 @@ static void instr_basic_block(GumStalkerIterator *iterator,
 
     if (instr->address == entry_start) { entry_prologue(iterator, output); }
     if (instr->address == persistent_start) { persistent_prologue(output); }
+    if (instr->address == persistent_ret) { persistent_epilogue(output); }
 
     /*
      * Until we reach AFL_ENTRYPOINT (assumed to be main if not specified) or

frida_mode/src/persistent/persistent.c

@@ -12,6 +12,9 @@ int                    __afl_sharedmem_fuzzing = 0;
 afl_persistent_hook_fn hook = NULL;
 guint64                persistent_start = 0;
 guint64                persistent_count = 0;
+guint64                persistent_ret = 0;
+guint64                persistent_ret_offset = 0;
+gboolean               persistent_debug = FALSE;
 
 void persistent_init(void) {
 
@@ -19,12 +22,36 @@ void persistent_init(void) {
 
   persistent_start = util_read_address("AFL_FRIDA_PERSISTENT_ADDR");
   persistent_count = util_read_num("AFL_FRIDA_PERSISTENT_CNT");
+  persistent_ret = util_read_address("AFL_FRIDA_PERSISTENT_RET");
+  persistent_ret_offset =
+      util_read_address("AFL_FRIDA_PERSISTENT_RETADDR_OFFSET");
+
+  if (getenv("AFL_FRIDA_PERSISTENT_DEBUG") != NULL) { persistent_debug = TRUE; }
+
+  if (persistent_count != 0 && persistent_start == 0) {
 
-  if (persistent_count != 0 && persistent_start == 0)
     FATAL(
         "AFL_FRIDA_PERSISTENT_ADDR must be specified if "
         "AFL_FRIDA_PERSISTENT_CNT is");
 
+  }
+
+  if (persistent_ret != 0 && persistent_start == 0) {
+
+    FATAL(
+        "AFL_FRIDA_PERSISTENT_ADDR must be specified if "
+        "AFL_FRIDA_PERSISTENT_RET is");
+
+  }
+
+  if (persistent_ret_offset != 0 && persistent_ret == 0) {
+
+    FATAL(
+        "AFL_FRIDA_PERSISTENT_RET must be specified if "
+        "AFL_FRIDA_PERSISTENT_RETADDR_OFFSET is");
+
+  }
+
   if (persistent_start != 0 && persistent_count == 0) persistent_count = 1000;
 
   if (persistent_count != 0 && persistent_count < 100)
@@ -39,6 +66,11 @@ void persistent_init(void) {
       persistent_start == 0 ? ' ' : 'X', persistent_count);
   OKF("Instrumentation - hook [%s]", hook_name);
 
+  OKF("Instrumentation - persistent ret [%c] (0x%016" G_GINT64_MODIFIER "X)",
+      persistent_ret == 0 ? ' ' : 'X', persistent_ret);
+  OKF("Instrumentation - persistent ret offset [%c] (%" G_GINT64_MODIFIER "d)",
+      persistent_ret_offset == 0 ? ' ' : 'X', persistent_ret_offset);
+
   if (hook_name != NULL) {
 
     void *hook_obj = dlopen(hook_name, RTLD_NOW);

frida_mode/src/persistent/persistent_arm32.c

@@ -68,5 +68,12 @@ void persistent_prologue(GumStalkerOutput *output) {
 
 }
 
+void persistent_epilogue(GumStalkerOutput *output) {
+
+  UNUSED_PARAMETER(output);
+  FATAL("Persistent mode not supported on this architecture");
+
+}
+
 #endif
 

frida_mode/src/persistent/persistent_arm64.c

@@ -111,5 +111,12 @@ void persistent_prologue(GumStalkerOutput *output) {
 
 }
 
+void persistent_epilogue(GumStalkerOutput *output) {
+
+  UNUSED_PARAMETER(output);
+  FATAL("Persistent mode not supported on this architecture");
+
+}
+
 #endif
 

frida_mode/src/persistent/persistent_x64.c

@@ -1,9 +1,11 @@
 #include "frida-gum.h"
 
 #include "config.h"
+#include "debug.h"
 
 #include "instrument.h"
 #include "persistent.h"
+#include "util.h"
 
 #if defined(__x86_64__)
 
@@ -264,7 +266,6 @@ void persistent_prologue(GumStalkerOutput *output) {
   GumX86Writer *cw = output->writer.x86;
 
   gconstpointer loop = cw->code + 1;
-  // gum_x86_writer_put_breakpoint(cw);
 
   /* Stack must be 16-byte aligned per ABI */
   instrument_persitent_save_regs(cw, &saved_regs);
@@ -288,7 +289,9 @@ void persistent_prologue(GumStalkerOutput *output) {
   instrument_persitent_restore_regs(cw, &saved_regs);
   gconstpointer original = cw->code + 1;
   /* call original */
+
   gum_x86_writer_put_call_near_label(cw, original);
+
   /* jmp loop */
   gum_x86_writer_put_jmp_near_label(cw, loop);
 
@@ -300,9 +303,23 @@ void persistent_prologue(GumStalkerOutput *output) {
   /* original: */
   gum_x86_writer_put_label(cw, original);
 
+  if (persistent_debug) { gum_x86_writer_put_breakpoint(cw); }
+
   gum_x86_writer_flush(cw);
 
 }
 
+void persistent_epilogue(GumStalkerOutput *output) {
+
+  GumX86Writer *cw = output->writer.x86;
+
+  if (persistent_debug) { gum_x86_writer_put_breakpoint(cw); }
+
+  gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_RSP, GUM_REG_RSP,
+                                        persistent_ret_offset);
+  gum_x86_writer_put_ret(cw);
+
+}
+
 #endif
 

frida_mode/src/persistent/persistent_x86.c

@@ -244,9 +244,24 @@ void persistent_prologue(GumStalkerOutput *output) {
   /* original: */
   gum_x86_writer_put_label(cw, original);
 
+  if (persistent_debug) { gum_x86_writer_put_breakpoint(cw); }
+
   gum_x86_writer_flush(cw);
 
 }
 
+void persistent_epilogue(GumStalkerOutput *output) {
+
+  GumX86Writer *cw = output->writer.x86;
+
+  if (persistent_debug) { gum_x86_writer_put_breakpoint(cw); }
+
+  gum_x86_writer_put_lea_reg_reg_offset(cw, GUM_REG_ESP, GUM_REG_ESP,
+                                        persistent_ret_offset);
+
+  gum_x86_writer_put_ret(cw);
+
+}
+
 #endif
 

frida_mode/src/util.c

@@ -10,7 +10,7 @@ guint64 util_read_address(char *key) {
 
   if (!g_str_has_prefix(value_str, "0x")) {
 
-    FATAL("Invalid address should have 0x prefix: %s\n", value_str);
+    FATAL("Invalid address should have 0x prefix: %s=%s\n", key, value_str);
 
   }
 
@@ -20,8 +20,8 @@ guint64 util_read_address(char *key) {
 
     if (!g_ascii_isxdigit(*c)) {
 
-      FATAL("Invalid address not formed of hex digits: %s ('%c')\n", value_str,
-            *c);
+      FATAL("Invalid address not formed of hex digits: %s=%s ('%c')\n", key,
+            value_str, *c);
 
     }
 
@@ -30,7 +30,7 @@ guint64 util_read_address(char *key) {
   guint64 value = g_ascii_strtoull(value_str2, NULL, 16);
   if (value == 0) {
 
-    FATAL("Invalid address failed hex conversion: %s\n", value_str2);
+    FATAL("Invalid address failed hex conversion: %s=%s\n", key, value_str2);
 
   }
 
@@ -48,7 +48,8 @@ guint64 util_read_num(char *key) {
 
     if (!g_ascii_isdigit(*c)) {
 
-      FATAL("Invalid address not formed of decimal digits: %s\n", value_str);
+      FATAL("Invalid address not formed of decimal digits: %s=%s\n", key,
+            value_str);
 
     }
 
@@ -57,7 +58,7 @@ guint64 util_read_num(char *key) {
   guint64 value = g_ascii_strtoull(value_str, NULL, 10);
   if (value == 0) {
 
-    FATAL("Invalid address failed numeric conversion: %s\n", value_str);
+    FATAL("Invalid address failed numeric conversion: %s=%s\n", key, value_str);
 
   }
 

frida_mode/test/persistent_ret/GNUmakefile

@@ -0,0 +1,105 @@
+PWD:=$(shell pwd)/
+ROOT:=$(shell realpath $(PWD)../../..)/
+BUILD_DIR:=$(PWD)build/
+TESTINSTR_DATA_DIR:=$(BUILD_DIR)in/
+TESTINSTR_DATA_FILE:=$(TESTINSTR_DATA_DIR)in
+
+TESTINSTBIN:=$(BUILD_DIR)testinstr
+TESTINSTSRC:=$(PWD)testinstr.c
+
+QEMU_OUT:=$(BUILD_DIR)qemu-out
+FRIDA_OUT:=$(BUILD_DIR)frida-out
+
+ifndef ARCH
+
+ARCH=$(shell uname -m)
+ifeq "$(ARCH)" "aarch64"
+ ARCH:=arm64
+endif
+
+ifeq "$(ARCH)" "i686"
+ ARCH:=x86
+endif
+endif
+
+ARCH=$(shell uname -m)
+ifeq "$(ARCH)" "aarch64"
+ AFL_FRIDA_PERSISTENT_ADDR=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s main -b 0x0000aaaaaaaaa000)
+ AFL_FRIDA_PERSISTENT_RET=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s slow -b 0x0000aaaaaaaaa000)
+endif
+
+ifeq "$(ARCH)" "x86_64"
+ AFL_FRIDA_PERSISTENT_ADDR=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s main -b 0x0000555555554000)
+ AFL_FRIDA_PERSISTENT_RET=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s slow -b 0x0000555555554000)
+endif
+
+ifeq "$(ARCH)" "x86"
+ AFL_FRIDA_PERSISTENT_ADDR=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s main -b 0x56555000)
+ AFL_FRIDA_PERSISTENT_RET=$(shell $(PWD)get_symbol_addr.py -f $(TESTINSTBIN) -s slow -b 0x56555000)
+endif
+
+AFL_FRIDA_PERSISTENT_RETADDR_OFFSET:=0x50
+
+.PHONY: all 32 clean qemu frida
+
+all: $(TESTINSTBIN)
+	make -C $(ROOT)frida_mode/
+
+32:
+	CFLAGS="-m32" LDFLAGS="-m32" ARCH="x86" make all
+
+$(BUILD_DIR):
+	mkdir -p $@
+
+$(TESTINSTR_DATA_DIR): | $(BUILD_DIR)
+	mkdir -p $@
+
+$(TESTINSTR_DATA_FILE): | $(TESTINSTR_DATA_DIR)
+	echo -n "000" > $@
+
+$(TESTINSTBIN): $(TESTINSTSRC) | $(BUILD_DIR)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
+
+clean:
+	rm -rf $(BUILD_DIR)
+
+frida: $(TESTINSTBIN) $(TESTINSTR_DATA_FILE)
+	AFL_FRIDA_PERSISTENT_ADDR=$(AFL_FRIDA_PERSISTENT_ADDR) \
+	$(ROOT)afl-fuzz \
+		-D \
+		-O \
+		-i $(TESTINSTR_DATA_DIR) \
+		-o $(FRIDA_OUT) \
+		-- \
+			$(TESTINSTBIN) @@
+
+frida_ret: $(TESTINSTBIN) $(TESTINSTR_DATA_FILE)
+	AFL_FRIDA_PERSISTENT_ADDR=$(AFL_FRIDA_PERSISTENT_ADDR) \
+	AFL_FRIDA_PERSISTENT_RET=$(AFL_FRIDA_PERSISTENT_RET) \
+	AFL_FRIDA_PERSISTENT_RETADDR_OFFSET=$(AFL_FRIDA_PERSISTENT_RETADDR_OFFSET) \
+	$(ROOT)afl-fuzz \
+		-D \
+		-O \
+		-i $(TESTINSTR_DATA_DIR) \
+		-o $(FRIDA_OUT) \
+		-- \
+			$(TESTINSTBIN) @@
+
+debug: $(TESTINSTR_DATA_FILE)
+	gdb \
+		--ex 'set environment AFL_FRIDA_PERSISTENT_ADDR=$(AFL_FRIDA_PERSISTENT_ADDR)' \
+		--ex 'set environment AFL_FRIDA_PERSISTENT_RET=$(AFL_FRIDA_PERSISTENT_RET)' \
+		--ex 'set environment AFL_FRIDA_PERSISTENT_RETADDR_OFFSET=$(AFL_FRIDA_PERSISTENT_RETADDR_OFFSET)' \
+		--ex 'set environment AFL_FRIDA_PERSISTENT_DEBUG=1' \
+		--ex 'set environment AFL_DEBUG_CHILD=1' \
+		--ex 'set environment LD_PRELOAD=$(ROOT)afl-frida-trace.so' \
+		--ex 'set disassembly-flavor intel' \
+		--args $(TESTINSTBIN) $(TESTINSTR_DATA_FILE)
+
+run: $(TESTINSTR_DATA_FILE)
+	AFL_FRIDA_PERSISTENT_ADDR=$(AFL_FRIDA_PERSISTENT_ADDR) \
+	AFL_FRIDA_PERSISTENT_RET=$(AFL_FRIDA_PERSISTENT_RET) \
+	AFL_FRIDA_PERSISTENT_RETADDR_OFFSET=$(AFL_FRIDA_PERSISTENT_RETADDR_OFFSET) \
+	AFL_DEBUG_CHILD=1 \
+	LD_PRELOAD=$(ROOT)afl-frida-trace.so \
+		$(TESTINSTBIN) $(TESTINSTR_DATA_FILE)

frida_mode/test/persistent_ret/Makefile

@@ -0,0 +1,22 @@
+all:
+	@echo trying to use GNU make...
+	@gmake all || echo please install GNUmake
+
+32:
+	@echo trying to use GNU make...
+	@gmake 32 || echo please install GNUmake
+
+clean:
+	@gmake clean
+
+frida:
+	@gmake frida
+
+frida_ret:
+	@gmake frida_ret
+
+debug:
+	@gmake debug
+
+run:
+	@gmake run

frida_mode/test/persistent_ret/get_symbol_addr.py

@@ -0,0 +1,36 @@
+#!/usr/bin/python3
+import argparse
+from elftools.elf.elffile import ELFFile
+
+def process_file(file, symbol, base):
+    with open(file, 'rb') as f:
+        elf = ELFFile(f)
+        symtab = elf.get_section_by_name('.symtab')
+        mains = symtab.get_symbol_by_name(symbol)
+        if len(mains) != 1:
+            print ("Failed to find main")
+            return 1
+
+        main_addr = mains[0]['st_value']
+        main = base + main_addr
+        print ("0x%016x" % main)
+        return 0
+
+def hex_value(x):
+    return int(x, 16)
+
+def main():
+    parser = argparse.ArgumentParser(description='Process some integers.')
+    parser.add_argument('-f', '--file', dest='file', type=str,
+                    help='elf file name', required=True)
+    parser.add_argument('-s', '--symbol', dest='symbol', type=str,
+                    help='symbol name', required=True)
+    parser.add_argument('-b', '--base', dest='base', type=hex_value,
+                    help='elf base address', required=True)
+
+    args = parser.parse_args()
+    return process_file (args.file, args.symbol, args.base)
+
+if __name__ == "__main__":
+    ret = main()
+    exit(ret)

frida_mode/test/persistent_ret/testinstr.c

@@ -0,0 +1,120 @@
+/*
+   american fuzzy lop++ - a trivial program to test the build
+   --------------------------------------------------------
+   Originally written by Michal Zalewski
+   Copyright 2014 Google Inc. All rights reserved.
+   Copyright 2019-2020 AFLplusplus Project. 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
+ */
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#ifdef __APPLE__
+  #define TESTINSTR_SECTION
+#else
+  #define TESTINSTR_SECTION __attribute__((section(".testinstr")))
+#endif
+
+void testinstr(char *buf, int len) {
+
+  if (len < 1) return;
+  buf[len] = 0;
+
+  // we support three input cases
+  if (buf[0] == '0')
+    printf("Looks like a zero to me!\n");
+  else if (buf[0] == '1')
+    printf("Pretty sure that is a one!\n");
+  else
+    printf("Neither one or zero? How quaint!\n");
+
+}
+
+void slow() {
+
+  usleep(100000);
+
+}
+
+TESTINSTR_SECTION int main(int argc, char **argv) {
+
+  char * file;
+  int    fd = -1;
+  off_t  len;
+  char * buf = NULL;
+  size_t n_read;
+  int    result = -1;
+
+  if (argc != 2) { return 1; }
+
+  do {
+
+    file = argv[1];
+
+    dprintf(STDERR_FILENO, "Running: %s\n", file);
+
+    fd = open(file, O_RDONLY);
+    if (fd < 0) {
+
+      perror("open");
+      break;
+
+    }
+
+    len = lseek(fd, 0, SEEK_END);
+    if (len < 0) {
+
+      perror("lseek (SEEK_END)");
+      break;
+
+    }
+
+    if (lseek(fd, 0, SEEK_SET) != 0) {
+
+      perror("lseek (SEEK_SET)");
+      break;
+
+    }
+
+    buf = malloc(len);
+    if (buf == NULL) {
+
+      perror("malloc");
+      break;
+
+    }
+
+    n_read = read(fd, buf, len);
+    if (n_read != len) {
+
+      perror("read");
+      break;
+
+    }
+
+    dprintf(STDERR_FILENO, "Running:    %s: (%zd bytes)\n", file, n_read);
+
+    testinstr(buf, len);
+    dprintf(STDERR_FILENO, "Done:    %s: (%zd bytes)\n", file, n_read);
+
+    slow();
+
+    result = 0;
+
+  } while (false);
+
+  if (buf != NULL) { free(buf); }
+
+  if (fd != -1) { close(fd); }
+
+  return result;
+
+}
+

include/envs.h

@@ -62,7 +62,10 @@ static char *afl_environment_variables[] = {
     "AFL_FRIDA_INST_TRACE",
     "AFL_FRIDA_PERSISTENT_ADDR",
     "AFL_FRIDA_PERSISTENT_CNT",
+    "AFL_FRIDA_PERSISTENT_DEBUG",
     "AFL_FRIDA_PERSISTENT_HOOK",
+    "AFL_FRIDA_PERSISTENT_RET",
+    "AFL_FRIDA_PERSISTENT_RETADDR_OFFSET",
     "AFL_FUZZER_ARGS",  // oss-fuzz
     "AFL_GDB",
     "AFL_GCC_ALLOWLIST",