Android中实现对/system/bin/surfaceflinger进程进行拦截和注入
16lz
2021-01-26
对于Android for arm上的so注入（inject）和挂钩（hook），网上已有牛人给出了代码inject。由于实现中的ptrace函数是依赖于平台的，所以不经改动只能用于arm平台。本文将之扩展了一下，使它能够通用于Android的x86和arm平台。Arm平台部分基本重用了inject中的代码，其中因为汇编不好移植且容易出错，所以把shellcode.s用ptrace_call替换掉了，另外保留了mmap，用来传字符串参数，当然也可以通过栈来传，但栈里和其它东西混一起，一弄不好就会隔儿了，所以还是保险点好。最后注意设备要root。
还有就是要在Linux中配置一下NDK编译环境呀~~(这个可以google了~~)
首先创建目录及文件：
文件夹：jni
文件：
inject.c
Android.mk
Application.mk
(说明：由于NDK编译的条件限制，所以我们需要创建的jni文件夹，当然这个文件的名字必须是jni)
注入的核心源代码：
inject.c
#include <stdio.h> #include <stdlib.h> #include <asm/user.h> #include <asm/ptrace.h> #include <sys/ptrace.h> #include <sys/wait.h> #include <sys/mman.h> #include <dlfcn.h> #include <dirent.h> #include <unistd.h> #include <string.h> #include <elf.h> #include <android/log.h> #if defined(__i386__) #define pt_regs user_regs_struct #endif #define ENABLE_DEBUG 1 #if ENABLE_DEBUG #define LOG_TAG "INJECT" #define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG, fmt, ##args) #define DEBUG_PRINT(format,args...) \ LOGD(format, ##args) #else #define DEBUG_PRINT(format,args...) #endif #define CPSR_T_MASK ( 1u << 5 ) const char *libc_path = "/system/lib/libc.so"; const char *linker_path = "/system/bin/linker"; int ptrace_readdata(pid_t pid, uint8_t *src, uint8_t *buf, size_t size) { uint32_t i, j, remain; uint8_t *laddr; union u { long val; char chars[sizeof(long)]; } d; j = size / 4; remain = size % 4; laddr = buf; for (i = 0; i < j; i ++) { d.val = ptrace(PTRACE_PEEKTEXT, pid, src, 0); memcpy(laddr, d.chars, 4); src += 4; laddr += 4; } if (remain > 0) { d.val = ptrace(PTRACE_PEEKTEXT, pid, src, 0); memcpy(laddr, d.chars, remain); } return 0; } int ptrace_writedata(pid_t pid, uint8_t *dest, uint8_t *data, size_t size) { uint32_t i, j, remain; uint8_t *laddr; union u { long val; char chars[sizeof(long)]; } d; j = size / 4; remain = size % 4; laddr = data; for (i = 0; i < j; i ++) { memcpy(d.chars, laddr, 4); ptrace(PTRACE_POKETEXT, pid, dest, d.val); dest += 4; laddr += 4; } if (remain > 0) { d.val = ptrace(PTRACE_PEEKTEXT, pid, dest, 0); for (i = 0; i < remain; i ++) { d.chars[i] = *laddr ++; } ptrace(PTRACE_POKETEXT, pid, dest, d.val); } return 0; } #if defined(__arm__) int ptrace_call(pid_t pid, uint32_t addr, long *params, uint32_t num_params, struct pt_regs* regs) { uint32_t i; for (i = 0; i < num_params && i < 4; i ++) { regs->uregs[i] = params[i]; } // // push remained params onto stack // if (i < num_params) { regs->ARM_sp -= (num_params - i) * sizeof(long) ; ptrace_writedata(pid, (void *)regs->ARM_sp, (uint8_t *)¶ms[i], (num_params - i) * sizeof(long)); } regs->ARM_pc = addr; if (regs->ARM_pc & 1) { /* thumb */ regs->ARM_pc &= (~1u); regs->ARM_cpsr |= CPSR_T_MASK; } else { /* arm */ regs->ARM_cpsr &= ~CPSR_T_MASK; } regs->ARM_lr = 0; if (ptrace_setregs(pid, regs) == -1 || ptrace_continue(pid) == -1) { printf("error\n"); return -1; } int stat = 0; waitpid(pid, &stat, WUNTRACED); while (stat != 0xb7f) { if (ptrace_continue(pid) == -1) { printf("error\n"); return -1; } waitpid(pid, &stat, WUNTRACED); } return 0; } #elif defined(__i386__) long ptrace_call(pid_t pid, uint32_t addr, long *params, uint32_t num_params, struct user_regs_struct * regs) { regs->esp -= (num_params) * sizeof(long) ; ptrace_writedata(pid, (void *)regs->esp, (uint8_t *)params, (num_params) * sizeof(long)); long tmp_addr = 0x00; regs->esp -= sizeof(long); ptrace_writedata(pid, regs->esp, (char *)&tmp_addr, sizeof(tmp_addr)); regs->eip = addr; if (ptrace_setregs(pid, regs) == -1 || ptrace_continue( pid) == -1) { printf("error\n"); return -1; } int stat = 0; waitpid(pid, &stat, WUNTRACED); while (stat != 0xb7f) { if (ptrace_continue(pid) == -1) { printf("error\n"); return -1; } waitpid(pid, &stat, WUNTRACED); } return 0; } #else #error "Not supported" #endif int ptrace_getregs(pid_t pid, struct pt_regs * regs) { if (ptrace(PTRACE_GETREGS, pid, NULL, regs) < 0) { perror("ptrace_getregs: Can not get register values"); return -1; } return 0; } int ptrace_setregs(pid_t pid, struct pt_regs * regs) { if (ptrace(PTRACE_SETREGS, pid, NULL, regs) < 0) { perror("ptrace_setregs: Can not set register values"); return -1; } return 0; } int ptrace_continue(pid_t pid) { if (ptrace(PTRACE_CONT, pid, NULL, 0) < 0) { perror("ptrace_cont"); return -1; } return 0; } int ptrace_attach(pid_t pid) { if (ptrace(PTRACE_ATTACH, pid, NULL, 0) < 0) { perror("ptrace_attach"); return -1; } int status = 0; waitpid(pid, &status , WUNTRACED); return 0; } int ptrace_detach(pid_t pid) { if (ptrace(PTRACE_DETACH, pid, NULL, 0) < 0) { perror("ptrace_detach"); return -1; } return 0; } void* get_module_base(pid_t pid, const char* module_name) { FILE *fp; long addr = 0; char *pch; char filename[32]; char line[1024]; if (pid < 0) { /* self process */ snprintf(filename, sizeof(filename), "/proc/self/maps", pid); } else { snprintf(filename, sizeof(filename), "/proc/%d/maps", pid); } fp = fopen(filename, "r"); if (fp != NULL) { while (fgets(line, sizeof(line), fp)) { if (strstr(line, module_name)) { pch = strtok( line, "-" ); addr = strtoul( pch, NULL, 16 ); if (addr == 0x8000) addr = 0; break; } } fclose(fp) ; } return (void *)addr; } void* get_remote_addr(pid_t target_pid, const char* module_name, void* local_addr) { void* local_handle, *remote_handle; local_handle = get_module_base(-1, module_name); remote_handle = get_module_base(target_pid, module_name); DEBUG_PRINT("[+] get_remote_addr: local[%x], remote[%x]\n", local_handle, remote_handle); void * ret_addr = (void *)((uint32_t)local_addr + (uint32_t)remote_handle - (uint32_t)local_handle); #if defined(__i386__) if (!strcmp(module_name, libc_path)) { ret_addr += 2; } #endif return ret_addr; } int find_pid_of(const char *process_name) { int id; pid_t pid = -1; DIR* dir; FILE *fp; char filename[32]; char cmdline[256]; struct dirent * entry; if (process_name == NULL) return -1; dir = opendir("/proc"); if (dir == NULL) return -1; while((entry = readdir(dir)) != NULL) { id = atoi(entry->d_name); if (id != 0) { sprintf(filename, "/proc/%d/cmdline", id); fp = fopen(filename, "r"); if (fp) { fgets(cmdline, sizeof(cmdline), fp); fclose(fp); if (strcmp(process_name, cmdline) == 0) { /* process found */ pid = id; break; } } } } closedir(dir); return pid; } long ptrace_retval(struct pt_regs * regs) { #if defined(__arm__) return regs->ARM_r0; #elif defined(__i386__) return regs->eax; #else #error "Not supported" #endif } long ptrace_ip(struct pt_regs * regs) { #if defined(__arm__) return regs->ARM_pc; #elif defined(__i386__) return regs->eip; #else #error "Not supported" #endif } int ptrace_call_wrapper(pid_t target_pid, const char * func_name, void * func_addr, long * parameters, int param_num, struct pt_regs * regs) { DEBUG_PRINT("[+] Calling %s in target process.\n", func_name); if (ptrace_call(target_pid, (uint32_t)func_addr, parameters, param_num, regs) == -1) return -1; if (ptrace_getregs(target_pid, regs) == -1) return -1; DEBUG_PRINT("[+] Target process returned from %s, return value=%x, pc=%x \n", func_name, ptrace_retval(regs), ptrace_ip(regs)); return 0; } int inject_remote_process(pid_t target_pid, const char *library_path, const char *function_name, const char *param, size_t param_size) { int ret = -1; void *mmap_addr, *dlopen_addr, *dlsym_addr, *dlclose_addr, *dlerror_addr; void *local_handle, *remote_handle, *dlhandle; uint8_t *map_base = 0; uint8_t *dlopen_param1_ptr, *dlsym_param2_ptr, *saved_r0_pc_ptr, *inject_param_ptr, *remote_code_ptr, *local_code_ptr; struct pt_regs regs, original_regs; extern uint32_t _dlopen_addr_s, _dlopen_param1_s, _dlopen_param2_s, _dlsym_addr_s, \ _dlsym_param2_s, _dlclose_addr_s, _inject_start_s, _inject_end_s, _inject_function_param_s, \ _saved_cpsr_s, _saved_r0_pc_s; uint32_t code_length; long parameters[10]; DEBUG_PRINT("[+] Injecting process: %d\n", target_pid); if (ptrace_attach(target_pid) == -1) goto exit; if (ptrace_getregs(target_pid, ®s) == -1) goto exit; /* save original registers */ memcpy(&original_regs, ®s, sizeof(regs)); mmap_addr = get_remote_addr(target_pid, libc_path, (void *)mmap); DEBUG_PRINT("[+] Remote mmap address: %x\n", mmap_addr); /* call mmap */ parameters[0] = 0; // addr parameters[1] = 0x4000; // size parameters[2] = PROT_READ | PROT_WRITE | PROT_EXEC; // prot parameters[3] = MAP_ANONYMOUS | MAP_PRIVATE; // flags parameters[4] = 0; //fd parameters[5] = 0; //offset if (ptrace_call_wrapper(target_pid, "mmap", mmap_addr, parameters, 6, ®s) == -1) goto exit; map_base = ptrace_retval(®s); dlopen_addr = get_remote_addr( target_pid, linker_path, (void *)dlopen ); dlsym_addr = get_remote_addr( target_pid, linker_path, (void *)dlsym ); dlclose_addr = get_remote_addr( target_pid, linker_path, (void *)dlclose ); dlerror_addr = get_remote_addr( target_pid, linker_path, (void *)dlerror ); DEBUG_PRINT("[+] Get imports: dlopen: %x, dlsym: %x, dlclose: %x, dlerror: %x\n", dlopen_addr, dlsym_addr, dlclose_addr, dlerror_addr); printf("library path = %s\n", library_path); ptrace_writedata(target_pid, map_base, library_path, strlen(library_path) + 1); parameters[0] = map_base; parameters[1] = RTLD_NOW| RTLD_GLOBAL; if (ptrace_call_wrapper(target_pid, "dlopen", dlopen_addr, parameters, 2, ®s) == -1) goto exit; void * sohandle = ptrace_retval(®s); #define FUNCTION_NAME_ADDR_OFFSET 0x100 ptrace_writedata(target_pid, map_base + FUNCTION_NAME_ADDR_OFFSET, function_name, strlen(function_name) + 1); parameters[0] = sohandle; parameters[1] = map_base + FUNCTION_NAME_ADDR_OFFSET; if (ptrace_call_wrapper(target_pid, "dlsym", dlsym_addr, parameters, 2, ®s) == -1) goto exit; void * hook_entry_addr = ptrace_retval(®s); DEBUG_PRINT("hook_entry_addr = %p\n", hook_entry_addr); #define FUNCTION_PARAM_ADDR_OFFSET 0x200 ptrace_writedata(target_pid, map_base + FUNCTION_PARAM_ADDR_OFFSET, param, strlen(param) + 1); parameters[0] = map_base + FUNCTION_PARAM_ADDR_OFFSET; if (ptrace_call_wrapper(target_pid, "hook_entry", hook_entry_addr, parameters, 1, ®s) == -1) goto exit; printf("Press enter to dlclose and detach\n"); getchar(); parameters[0] = sohandle; if (ptrace_call_wrapper(target_pid, "dlclose", dlclose, parameters, 1, ®s) == -1) goto exit; /* restore */ ptrace_setregs(target_pid, &original_regs); ptrace_detach(target_pid); ret = 0; exit: return ret; } int main(int argc, char** argv) { pid_t target_pid; target_pid = find_pid_of("/system/bin/surfaceflinger"); if (-1 == target_pid) { printf("Can't find the process\n"); return -1; } //target_pid = find_pid_of("/data/test"); inject_remote_process(target_pid, "/data/libhello.so", "hook_entry", "I'm parameter!", strlen("I'm parameter!")); return 0; } 注意上面的/system/bin/surfaceflinger进程我随手写的，你的设备上不一定有。没有的话挑其它的也行，前提是ps命令里能找到。
Android.mk:
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := inject LOCAL_SRC_FILES := inject.c #shellcode.s LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog #LOCAL_FORCE_STATIC_EXECUTABLE := true include $(BUILD_EXECUTABLE)
Application.mk:
APP_ABI := x86 armeabi-v7a
运行nkd-build编译成生x86和arm平台下的可执行文件：
再来生成要注入的so，创建目录及文件：
jni
suf.c
Android.mk
Application.mk
suf.c:
#include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <android/log.h> #include <elf.h> #include <fcntl.h> #define LOG_TAG "DEBUG" #define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, fmt, ##args) int hook_entry(char * a){ LOGD("Hook success, pid = %d\n", getpid()); LOGD("Hello %s\n", a); return 0; } Android.mk:
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog #LOCAL_ARM_MODE := arm LOCAL_MODULE := suf LOCAL_SRC_FILES := suf.c include $(BUILD_SHARED_LIBRARY)
Application.mk:
APP_ABI := x86 armeabi-v7a
运行nkd-build编译成生x86和arm平台下的so：
然后就可以跑起来试试了，连接root过的Android设备或者打开模拟器。将inject和libhello.so拷入设备，设执行权限，执行：
先看看被注入进程（surfaceflinger）的mmap，可以看到我们的so已经被加载了，紧接着的那一块就是我们mmap出来的：
从logcat中也可以看到so注入成功，并且以被注入进程的身份执行了so中的代码.
将编译好的文件拷贝到设备的data目录(这里不一定要拷贝到data目录下面，这个可以看自己的需要了)下面：
adb push inject /data/
adb push libsuf.so /data/
然后修改一下文件的权限
chmod 777 inject
然后运行inject,同时我们可以查询一下/system/bin/surfaceflinger进程信息，可以看到，我们将libsuf.so注入到了此进程中.
简单的注入成功，现在我们再来做一个实验，就是应用这套机制来截获surfaceflinger中的eglSwapBuffers调用，然后用我们自己的函数来替换掉原来的eglSwapBuffers调用。关于截系统中的函数调用网上有例子，这里依葫芦画瓢。首先将suf.c改下：
#include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <android/log.h> #include <EGL/egl.h> #include <GLES/gl.h> #include <elf.h> #include <fcntl.h> #include <sys/mman.h> #define LOG_TAG "DEBUG" #define LOGD(fmt, args...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, fmt, ##args) EGLBoolean (*old_eglSwapBuffers)(EGLDisplay dpy, EGLSurface surf) = -1; EGLBoolean new_eglSwapBuffers(EGLDisplay dpy, EGLSurface surface) { LOGD("New eglSwapBuffers\n"); if (old_eglSwapBuffers == -1) LOGD("error\n"); return old_eglSwapBuffers(dpy, surface); } void* get_module_base(pid_t pid, const char* module_name) { FILE *fp; long addr = 0; char *pch; char filename[32]; char line[1024]; if (pid < 0) { /* self process */ snprintf(filename, sizeof(filename), "/proc/self/maps", pid); } else { snprintf(filename, sizeof(filename), "/proc/%d/maps", pid); } fp = fopen(filename, "r"); if (fp != NULL) { while (fgets(line, sizeof(line), fp)) { if (strstr(line, module_name)) { pch = strtok( line, "-" ); addr = strtoul( pch, NULL, 16 ); if (addr == 0x8000) addr = 0; break; } } fclose(fp) ; } return (void *)addr; } #define LIBSF_PATH "/system/lib/libsurfaceflinger.so" int hook_eglSwapBuffers() { old_eglSwapBuffers = eglSwapBuffers; LOGD("Orig eglSwapBuffers = %p\n", old_eglSwapBuffers); void * base_addr = get_module_base(getpid(), LIBSF_PATH); LOGD("libsurfaceflinger.so address = %p\n", base_addr); int fd; fd = open(LIBSF_PATH, O_RDONLY); if (-1 == fd) { LOGD("error\n"); return -1; } Elf32_Ehdr ehdr; read(fd, &ehdr, sizeof(Elf32_Ehdr)); unsigned long shdr_addr = ehdr.e_shoff; int shnum = ehdr.e_shnum; int shent_size = ehdr.e_shentsize; unsigned long stridx = ehdr.e_shstrndx; Elf32_Shdr shdr; lseek(fd, shdr_addr + stridx * shent_size, SEEK_SET); read(fd, &shdr, shent_size); char * string_table = (char *)malloc(shdr.sh_size); lseek(fd, shdr.sh_offset, SEEK_SET); read(fd, string_table, shdr.sh_size); lseek(fd, shdr_addr, SEEK_SET); int i; uint32_t out_addr = 0; uint32_t out_size = 0; uint32_t got_item = 0; int32_t got_found = 0; for (i = 0; i < shnum; i++) { read(fd, &shdr, shent_size); if (shdr.sh_type == SHT_PROGBITS) { int name_idx = shdr.sh_name; if (strcmp(&(string_table[name_idx]), ".got.plt") == 0 || strcmp(&(string_table[name_idx]), ".got") == 0) { out_addr = base_addr + shdr.sh_addr; out_size = shdr.sh_size; LOGD("out_addr = %lx, out_size = %lx\n", out_addr, out_size); for (i = 0; i < out_size; i += 4) { got_item = *(uint32_t *)(out_addr + i); if (got_item == old_eglSwapBuffers) { LOGD("Found eglSwapBuffers in got\n"); got_found = 1; uint32_t page_size = getpagesize(); uint32_t entry_page_start = (out_addr + i) & (~(page_size - 1)); mprotect((uint32_t *)entry_page_start, page_size, PROT_READ | PROT_WRITE); *(uint32_t *)(out_addr + i) = new_eglSwapBuffers; break; } else if (got_item == new_eglSwapBuffers) { LOGD("Already hooked\n"); break; } } if (got_found) break; } } } free(string_table); close(fd); } int hook_entry(char * a){ LOGD("Hook success\n"); LOGD("Start hooking\n"); hook_eglSwapBuffers(); return 0; } 其实这种查找方法有点简单粗暴，要是正式应用的话可以在动态符号表中查找这个符号的got地址。
接着Android.mk改为：
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog -lEGL #LOCAL_ARM_MODE := arm LOCAL_MODULE := hello LOCAL_SRC_FILES := hello.c include $(BUILD_SHARED_LIBRARY)
Application.mk :
APP_ABI := x86 armeabi-v7a APP_PLATFORM := android-14
运行ndk-build编译
和上面一样运行，查看logcat，我们可以看到surfaceflinger中调用eglSwapBuffers的地址已被替换成我们的版本：
D/INJECT ( 2231): [+] Injecting process: 1728
D/INJECT ( 2231): [+] get_remote_addr: local[b7e4f000], remote[b7e73000]
D/INJECT ( 2231): [+] Remote mmap address: b7e9fe32
D/INJECT ( 2231): [+] Calling mmap in target process.
D/INJECT ( 2231): [+] Target process returned from mmap, return value=b4f1c000, pc=0
D/INJECT ( 2231): [+] get_remote_addr: local[b7f00000], remote[b7f7e000]
D/INJECT ( 2231): [+] get_remote_addr: local[b7f00000], remote[b7f7e000]
D/INJECT ( 2231): [+] get_remote_addr: local[b7f00000], remote[b7f7e000]
D/INJECT ( 2231): [+] get_remote_addr: local[b7f00000], remote[b7f7e000]
D/INJECT ( 2231): [+] Get imports: dlopen: b7f84f50, dlsym: b7f84fd0, dlclose: b7f84de0, dlerror: b7f84dc0
D/INJECT ( 2231): [+] Calling dlopen in target process.
D/INJECT ( 2231): [+] Target process returned from dlopen, return value=b7f995ec, pc=0
D/INJECT ( 2231): [+] Calling dlsym in target process.
D/INJECT ( 2231): [+] Target process returned from dlsym, return value=b4f17e10, pc=0
D/INJECT ( 2231): hook_entry_addr = 0xb4f17e10
D/DEBUG ( 1728): Hook success
D/DEBUG ( 1728): Start hooking
D/DEBUG ( 1728): Orig eglSwapBuffers = 0xb7d4a9c0
D/DEBUG ( 1728): libsurfaceflinger.so address = 0xb7f22000
D/DEBUG ( 1728): out_addr = b7f7aff4, out_size = 624
D/DEBUG ( 1728): Found eglSwapBuffers in got
...
D/DEBUG ( 1728): New eglSwapBuffers
D/DEBUG ( 1728): New eglSwapBuffers
D/DEBUG ( 1728): New eglSwapBuffers
...
Demo下载地址：http://download.csdn.net/detail/jiangwei0910410003/7926427
这篇文章就简单介绍了如何将对surfaceflinger进程进行注入和拦截的操作。这个还是很有用的，后续我们还会对system_process进程进行注入和拦截，那时候还会参考这篇文章。。
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