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@ -1,92 +1,94 @@
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/*
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Copyright 2015 Google LLC All rights reserved.
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Copyright 2015 Google LLC All rights reserved. // 版权声明，2015年谷歌公司所有权利保留
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at:
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Licensed under the Apache License, Version 2.0 (the "License"); // 根据Apache许可证第2.0版授权
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you may not use this file except in compliance with the License. // 除非遵守许可证，否则不得使用此文件
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You may obtain a copy of the License at: // 可以通过以下网址获得许可证副本
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http://www.apache.org/licenses/LICENSE-2.0
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http://www.apache.org/licenses/LICENSE-2.0 // 许可证的链接
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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Unless required by applicable law or agreed to in writing, software // 除非相关法律要求或书面协议，软件
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distributed under the License is distributed on an "AS IS" BASIS, // 在“按原样”基础上分发
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // 不提供任何形式的明示或暗示的保证或条件
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See the License for the specific language governing permissions and // 请参阅许可证以获取约束和限制的具体语言
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limitations under the License. // 在许可证下的限制条款
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*/
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/*
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american fuzzy lop - high-performance binary-only instrumentation
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american fuzzy lop - high-performance binary-only instrumentation // American Fuzzy Lop - 高性能二进制插桩
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-----------------------------------------------------------------
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Written by Andrew Griffiths <agriffiths@google.com> and
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Michal Zalewski <lcamtuf@google.com>
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Written by Andrew Griffiths <agriffiths@google.com> and // 由Andrew Griffiths和
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Michal Zalewski <lcamtuf@google.com> // Michal Zalewski编写
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Idea & design very much by Andrew Griffiths.
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Idea & design very much by Andrew Griffiths. // 概念和设计主要由Andrew Griffiths提出。
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This code is a shim patched into the separately-distributed source
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code of QEMU 2.10.0. It leverages the built-in QEMU tracing functionality
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to implement AFL-style instrumentation and to take care of the remaining
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parts of the AFL fork server logic.
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This code is a shim patched into the separately-distributed source // 此代码是补丁，插入到单独分发的源代码中
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code of QEMU 2.10.0. It leverages the built-in QEMU tracing functionality // QEMU 2.10.0的源代码中。 该代码利用了内置的QEMU跟踪功能
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to implement AFL-style instrumentation and to take care of the remaining // 实现AFL风格的插桩，并处理剩余
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parts of the AFL fork server logic. // AFL fork服务器逻辑的部分内容。
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The resulting QEMU binary is essentially a standalone instrumentation
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tool; for an example of how to leverage it for other purposes, you can
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have a look at afl-showmap.c.
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The resulting QEMU binary is essentially a standalone instrumentation // 生成的QEMU二进制文件基本上是一个独立的插桩工具
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tool; for an example of how to leverage it for other purposes, you can // 用于其他目的的示例可以参考
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have a look at afl-showmap.c. // afl-showmap.c
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*/
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#include <sys/shm.h>
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#include "../../config.h"
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#include <sys/shm.h> // 包含共享内存的头文件
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#include "../../config.h" // 包含项目配置的头文件
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/***************************
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* VARIOUS AUXILIARY STUFF *
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***************************/
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/* A snippet patched into tb_find_slow to inform the parent process that
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we have hit a new block that hasn't been translated yet, and to tell
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it to translate within its own context, too (this avoids translation
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overhead in the next forked-off copy). */
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/* A snippet patched into tb_find_slow to inform the parent process that // 一段插入到tb_find_slow中的代码，用于通知父进程
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we have hit a new block that hasn't been translated yet, and to tell // 我们已经遇到了一个尚未翻译的新块，并告诉父进程
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it to translate within its own context, too (this avoids translation // 也在其自己的上下文中翻译（这避免了在下一个
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overhead in the next forked-off copy). // 被fork的副本中出现翻译开销）。
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*/
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#define AFL_QEMU_CPU_SNIPPET1 do { \
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afl_request_tsl(pc, cs_base, flags); \
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} while (0)
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afl_request_tsl(pc, cs_base, flags); \ // 调用afl_request_tsl函数，传入参数
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} while (0) // 循环体
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/* This snippet kicks in when the instruction pointer is positioned at
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_start and does the usual forkserver stuff, not very different from
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/* This snippet kicks in when the instruction pointer is positioned at // 当指令指针位于_start位置时，此代码段生效
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_start and does the usual forkserver stuff, not very different from // 并执行常规的forkserver逻辑，与通过afl-as.h注入的逻辑没有太大区别
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regular instrumentation injected via afl-as.h. */
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#define AFL_QEMU_CPU_SNIPPET2 do { \
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if(itb->pc == afl_entry_point) { \
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afl_setup(); \
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afl_forkserver(cpu); \
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if(itb->pc == afl_entry_point) { \ // 如果当前程序计数器等于入口点
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afl_setup(); \ // 设置插桩环境
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afl_forkserver(cpu); \ // 启动fork服务器
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} \
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afl_maybe_log(itb->pc); \
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} while (0)
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afl_maybe_log(itb->pc); \ // 可能记录当前地址
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} while (0) // 循环体
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/* We use one additional file descriptor to relay "needs translation"
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/* We use one additional file descriptor to relay "needs translation" // 我们使用一个附加文件描述符来传递“需要翻译”的信息
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messages between the child and the fork server. */
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#define TSL_FD (FORKSRV_FD - 1)
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#define TSL_FD (FORKSRV_FD - 1) // 定义一个文件描述符，用于传递翻译请求
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/* This is equivalent to afl-as.h: */
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static unsigned char *afl_area_ptr;
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static unsigned char *afl_area_ptr; // 定义指向AFL区域的指针
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/* Exported variables populated by the code patched into elfload.c: */
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abi_ulong afl_entry_point, /* ELF entry point (_start) */
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afl_start_code, /* .text start pointer */
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afl_end_code; /* .text end pointer */
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abi_ulong afl_entry_point, /* ELF entry point (_start) */ // ELF入口点
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afl_start_code, /* .text start pointer */ // .text段起始指针
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afl_end_code; /* .text end pointer */ // .text段结束指针
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/* Set in the child process in forkserver mode: */
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static unsigned char afl_fork_child;
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unsigned int afl_forksrv_pid;
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static unsigned char afl_fork_child; // 用于标记是否在fork子进程中
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unsigned int afl_forksrv_pid; // fork服务器进程的PID
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/* Instrumentation ratio: */
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static unsigned int afl_inst_rms = MAP_SIZE;
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static unsigned int afl_inst_rms = MAP_SIZE; // 插桩比例
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/* Function declarations. */
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// 函数声明
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static void afl_setup(void);
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static void afl_forkserver(CPUState*);
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static inline void afl_maybe_log(abi_ulong);
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@ -96,16 +98,16 @@ static void afl_request_tsl(target_ulong, target_ulong, uint64_t);
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/* Data structure passed around by the translate handlers: */
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struct afl_tsl {
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target_ulong pc;
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target_ulong cs_base;
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uint64_t flags;
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struct afl_tsl { // 传递给翻译处理程序的数据结构
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target_ulong pc; // 当前程序计数器
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target_ulong cs_base; // 段基址
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uint64_t flags; // 标志
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};
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/* Some forward decls: */
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TranslationBlock *tb_htable_lookup(CPUState*, target_ulong, target_ulong, uint32_t);
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static inline TranslationBlock *tb_find(CPUState*, TranslationBlock*, int);
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TranslationBlock *tb_htable_lookup(CPUState*, target_ulong, target_ulong, uint32_t); // 查找翻译块的函数
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static inline TranslationBlock *tb_find(CPUState*, TranslationBlock*, int); // 查找翻译块的内联函数
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/*************************
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* ACTUAL IMPLEMENTATION *
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@ -113,201 +115,194 @@ static inline TranslationBlock *tb_find(CPUState*, TranslationBlock*, int);
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/* Set up SHM region and initialize other stuff. */
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static void afl_setup(void) {
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static void afl_setup(void) { // 设置共享内存区域并初始化其他内容
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char *id_str = getenv(SHM_ENV_VAR),
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*inst_r = getenv("AFL_INST_RATIO");
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char *id_str = getenv(SHM_ENV_VAR), // 获取共享内存环境变量
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*inst_r = getenv("AFL_INST_RATIO"); // 获取插桩比例环境变量
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int shm_id;
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int shm_id; // 共享内存标识符
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if (inst_r) {
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if (inst_r) { // 如果设置了插桩比例
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unsigned int r;
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unsigned int r; // 声明插桩比例变量
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r = atoi(inst_r);
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r = atoi(inst_r); // 将环境变量转为整数
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if (r > 100) r = 100;
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if (!r) r = 1;
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if (r > 100) r = 100; // 最大为100
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if (!r) r = 1; // 如果为0则设置为1
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afl_inst_rms = MAP_SIZE * r / 100;
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afl_inst_rms = MAP_SIZE * r / 100; // 计算实际插桩比例
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}
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if (id_str) {
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shm_id = atoi(id_str);
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afl_area_ptr = shmat(shm_id, NULL, 0);
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if (id_str) { // 如果设定了共享内存ID
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if (afl_area_ptr == (void*)-1) exit(1);
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shm_id = atoi(id_str); // 将ID转为整数
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afl_area_ptr = shmat(shm_id, NULL, 0); // 附加共享内存
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/* With AFL_INST_RATIO set to a low value, we want to touch the bitmap
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so that the parent doesn't give up on us. */
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if (afl_area_ptr == (void*)-1) exit(1); // 失败则退出
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if (inst_r) afl_area_ptr[0] = 1;
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/* With AFL_INST_RATIO set to a low value, we want to touch the bitmap //
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so that the parent doesn't give up on us. */ // 当插桩比例设置为较低值时，访问位图防止父进程放弃我们
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if (inst_r) afl_area_ptr[0] = 1; // 访问位图的第一个字节
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}
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if (getenv("AFL_INST_LIBS")) {
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afl_start_code = 0;
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afl_end_code = (abi_ulong)-1;
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if (getenv("AFL_INST_LIBS")) { // 如果设置了AFL_INST_LIBS环境变量
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afl_start_code = 0; // 设置代码段起始位置
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afl_end_code = (abi_ulong)-1; // 设置代码段结束位置
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}
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/* pthread_atfork() seems somewhat broken in util/rcu.c, and I'm
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not entirely sure what is the cause. This disables that
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behaviour, and seems to work alright? */
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/* pthread_atfork() seems somewhat broken in util/rcu.c, and I'm //
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not entirely sure what is the cause. This disables that //
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behaviour, and seems to work alright? */ // pthread_atfork()在util/rcu.c中似乎存在问题，这禁用此行为，并且有效
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rcu_disable_atfork();
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rcu_disable_atfork(); // 禁用atfork功能
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}
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/* Fork server logic, invoked once we hit _start. */
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static void afl_forkserver(CPUState *cpu) {
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static unsigned char tmp[4];
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static void afl_forkserver(CPUState *cpu) { // fork服务器逻辑，在_start时调用
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if (!afl_area_ptr) return;
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static unsigned char tmp[4]; // 临时缓冲区
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/* Tell the parent that we're alive. If the parent doesn't want
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to talk, assume that we're not running in forkserver mode. */
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if (!afl_area_ptr) return; // 如果指针为空则返回
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if (write(FORKSRV_FD + 1, tmp, 4) != 4) return;
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/* Tell the parent that we're alive. If the parent doesn't want //
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to talk, assume that we're not running in forkserver mode. */ // 告诉父进程我们已经活着，如果父进程不响应，则认为不在fork服务器模式
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afl_forksrv_pid = getpid();
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if (write(FORKSRV_FD + 1, tmp, 4) != 4) return; // 写入父进程
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/* All right, let's await orders... */
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afl_forksrv_pid = getpid(); // 获取当前进程ID
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while (1) {
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/* All right, let's await orders... */ // 好的，让我们等待命令…
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pid_t child_pid;
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int status, t_fd[2];
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while (1) { // 进入无限循环
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/* Whoops, parent dead? */
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pid_t child_pid; // 子进程ID
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int status, t_fd[2]; // 状态和文件描述符数组
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if (read(FORKSRV_FD, tmp, 4) != 4) exit(2);
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/* Whoops, parent dead? */ // 哎呀，父进程死了？
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/* Establish a channel with child to grab translation commands. We'll
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read from t_fd[0], child will write to TSL_FD. */
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if (read(FORKSRV_FD, tmp, 4) != 4) exit(2); // 读取父进程信息失败则退出
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if (pipe(t_fd) || dup2(t_fd[1], TSL_FD) < 0) exit(3);
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close(t_fd[1]);
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/* Establish a channel with child to grab translation commands. We'll //
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read from t_fd[0], child will write to TSL_FD. */ // 建立与子进程的通道获取翻译命令。我们从t_fd[0]读取，子进程写入TSL_FD。
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child_pid = fork();
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if (child_pid < 0) exit(4);
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if (pipe(t_fd) || dup2(t_fd[1], TSL_FD) < 0) exit(3); // 创建管道，复制描述符
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close(t_fd[1]); // 关闭写入端
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if (!child_pid) {
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child_pid = fork(); // 创建子进程
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if (child_pid < 0) exit(4); // 创建失败则退出
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/* Child process. Close descriptors and run free. */
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if (!child_pid) { // 如果是子进程
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afl_fork_child = 1;
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close(FORKSRV_FD);
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close(FORKSRV_FD + 1);
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close(t_fd[0]);
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return;
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/* Child process. Close descriptors and run free. */ // 子进程。关闭描述符，进入自由运行。
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afl_fork_child = 1; // 标记为子进程
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close(FORKSRV_FD); // 关闭fork服务器文件描述符
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close(FORKSRV_FD + 1); // 关闭fork服务器文件描述符的另一个副本
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close(t_fd[0]); // 关闭读取端
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return; // 返回
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}
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/* Parent. */
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/* Parent. */ // 父进程。
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close(TSL_FD);
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close(TSL_FD); // 关闭TSL文件描述符
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if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) exit(5);
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if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) exit(5); // 向父进程写入子进程ID，失败则退出。
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/* Collect translation requests until child dies and closes the pipe. */
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/* Collect translation requests until child dies and closes the pipe. */ // 收集翻译请求，直到子进程结束并关闭管道。
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afl_wait_tsl(cpu, t_fd[0]);
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afl_wait_tsl(cpu, t_fd[0]); // 等待翻译请求
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/* Get and relay exit status to parent. */
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/* Get and relay exit status to parent. */ // 获取子进程退出状态并传递给父进程。
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if (waitpid(child_pid, &status, 0) < 0) exit(6);
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if (write(FORKSRV_FD + 1, &status, 4) != 4) exit(7);
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if (waitpid(child_pid, &status, 0) < 0) exit(6); // 等待子进程结束，失败则退出
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if (write(FORKSRV_FD + 1, &status, 4) != 4) exit(7); // 向父进程写入状态，失败则退出
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}
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}
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/* The equivalent of the tuple logging routine from afl-as.h. */
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static inline void afl_maybe_log(abi_ulong cur_loc) {
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static inline void afl_maybe_log(abi_ulong cur_loc) { // 记录当前地址的内联函数
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static __thread abi_ulong prev_loc;
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static __thread abi_ulong prev_loc; // 上一个地址
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/* Optimize for cur_loc > afl_end_code, which is the most likely case on
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Linux systems. */
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/* Optimize for cur_loc > afl_end_code, which is the most likely case on //
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Linux systems. */ // 优化条件，常见于Linux系统
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if (cur_loc > afl_end_code || cur_loc < afl_start_code || !afl_area_ptr)
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return;
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if (cur_loc > afl_end_code || cur_loc < afl_start_code || !afl_area_ptr) // 如果当前地址不在有效范围
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return; // 返回
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/* Looks like QEMU always maps to fixed locations, so ASAN is not a
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|
concern. Phew. But instruction addresses may be aligned. Let's mangle
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|
the value to get something quasi-uniform. */
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|
/* Looks like QEMU always maps to fixed locations, so ASAN is not a //
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|
|
concern. Phew. But instruction addresses may be aligned. Let's mangle //
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|
the value to get something quasi-uniform. */ // QEMU似乎总是映射到固定位置，因此不需要担心ASAN。但指令地址可能会对齐。通过一些操作来获取统一值。
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cur_loc = (cur_loc >> 4) ^ (cur_loc << 8);
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|
|
cur_loc &= MAP_SIZE - 1;
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|
|
cur_loc = (cur_loc >> 4) ^ (cur_loc << 8); // 按位操作获取新值
|
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|
|
cur_loc &= MAP_SIZE - 1; // 避免越界
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|
|
/* Implement probabilistic instrumentation by looking at scrambled block
|
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|
|
address. This keeps the instrumented locations stable across runs. */
|
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|
|
/* Implement probabilistic instrumentation by looking at scrambled block //
|
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|
|
address. This keeps the instrumented locations stable across runs. */ // 通过查看混乱的块地址实现概率性插桩，这样可以在多次运行中保持插桩位置的稳定性。
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|
|
if (cur_loc >= afl_inst_rms) return;
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|
|
if (cur_loc >= afl_inst_rms) return; // 如果当前地址超过插桩比率，返回
|
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|
|
afl_area_ptr[cur_loc ^ prev_loc]++;
|
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|
|
prev_loc = cur_loc >> 1;
|
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|
|
afl_area_ptr[cur_loc ^ prev_loc]++; // 增加对应计数
|
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|
|
prev_loc = cur_loc >> 1; // 更新上一个位置
|
|
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|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
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|
|
/* This code is invoked whenever QEMU decides that it doesn't have a //
|
|
|
|
|
translation of a particular block and needs to compute it. When this happens, //
|
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|
|
we tell the parent to mirror the operation, so that the next fork() has a //
|
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|
|
cached copy. */ // 每当QEMU决定没有特定块的翻译并需要计算时，会调用此代码。当发生这种情况时，我们告诉父进程镜像操作，以便下一个fork()具有缓存副本。
|
|
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|
|
/* This code is invoked whenever QEMU decides that it doesn't have a
|
|
|
|
|
translation of a particular block and needs to compute it. When this happens,
|
|
|
|
|
we tell the parent to mirror the operation, so that the next fork() has a
|
|
|
|
|
cached copy. */
|
|
|
|
|
|
|
|
|
|
static void afl_request_tsl(target_ulong pc, target_ulong cb, uint64_t flags) {
|
|
|
|
|
static void afl_request_tsl(target_ulong pc, target_ulong cb, uint64_t flags) { // 请求翻译
|
|
|
|
|
|
|
|
|
|
struct afl_tsl t;
|
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|
|
|
struct afl_tsl t; // 创建AFI_TSL结构体
|
|
|
|
|
|
|
|
|
|
if (!afl_fork_child) return;
|
|
|
|
|
if (!afl_fork_child) return; // 如果不是子进程，返回
|
|
|
|
|
|
|
|
|
|
t.pc = pc;
|
|
|
|
|
t.cs_base = cb;
|
|
|
|
|
t.flags = flags;
|
|
|
|
|
t.pc = pc; // 设置程序计数器
|
|
|
|
|
t.cs_base = cb; // 设置基址
|
|
|
|
|
t.flags = flags; // 设置标志
|
|
|
|
|
|
|
|
|
|
if (write(TSL_FD, &t, sizeof(struct afl_tsl)) != sizeof(struct afl_tsl))
|
|
|
|
|
return;
|
|
|
|
|
if (write(TSL_FD, &t, sizeof(struct afl_tsl)) != sizeof(struct afl_tsl)) // 写入数据请求
|
|
|
|
|
return; // 返回
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* This is the other side of the same channel. Since timeouts are handled by
|
|
|
|
|
afl-fuzz simply killing the child, we can just wait until the pipe breaks. */
|
|
|
|
|
/* This is the other side of the same channel. Since timeouts are handled by //
|
|
|
|
|
afl-fuzz simply killing the child, we can just wait until the pipe breaks. */ // 这是同一通道的另一侧。由于超时通过afl-fuzz简单地终止子进程来处理，我们只需等待管道断开即可。
|
|
|
|
|
|
|
|
|
|
static void afl_wait_tsl(CPUState *cpu, int fd) {
|
|
|
|
|
static void afl_wait_tsl(CPUState *cpu, int fd) { // 等待翻译请求
|
|
|
|
|
|
|
|
|
|
struct afl_tsl t;
|
|
|
|
|
TranslationBlock *tb;
|
|
|
|
|
struct afl_tsl t; // 请求结构体
|
|
|
|
|
TranslationBlock *tb; // 翻译块
|
|
|
|
|
|
|
|
|
|
while (1) {
|
|
|
|
|
while (1) { // 无限循环
|
|
|
|
|
|
|
|
|
|
/* Broken pipe means it's time to return to the fork server routine. */
|
|
|
|
|
/* Broken pipe means it's time to return to the fork server routine. */ // 异常管道表示可以返回fork服务器例程
|
|
|
|
|
|
|
|
|
|
if (read(fd, &t, sizeof(struct afl_tsl)) != sizeof(struct afl_tsl))
|
|
|
|
|
break;
|
|
|
|
|
if (read(fd, &t, sizeof(struct afl_tsl)) != sizeof(struct afl_tsl)) // 读取请求数据
|
|
|
|
|
break; // 读取失败，退出循环
|
|
|
|
|
|
|
|
|
|
tb = tb_htable_lookup(cpu, t.pc, t.cs_base, t.flags);
|
|
|
|
|
tb = tb_htable_lookup(cpu, t.pc, t.cs_base, t.flags); // 查找翻译块
|
|
|
|
|
|
|
|
|
|
if(!tb) {
|
|
|
|
|
mmap_lock();
|
|
|
|
|
tb_lock();
|
|
|
|
|
tb_gen_code(cpu, t.pc, t.cs_base, t.flags, 0);
|
|
|
|
|
mmap_unlock();
|
|
|
|
|
tb_unlock();
|
|
|
|
|
if(!tb) { // 如果没有找到翻译块
|
|
|
|
|
mmap_lock(); // 锁定内存映射
|
|
|
|
|
tb_lock(); // 锁定翻译块
|
|
|
|
|
tb_gen_code(cpu, t.pc, t.cs_base, t.flags, 0); // 生成新的翻译块
|
|
|
|
|
mmap_unlock(); // 解锁内存映射
|
|
|
|
|
tb_unlock(); // 解锁翻译块
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
close(fd);
|
|
|
|
|
close(fd); // 关闭文件描述符
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
