execve args replace .

[w296488320]

Hi great developers, I had a problem recently about the execve parameter replacement. My requirement is to replace and modify (parameter 1) and (parameter 2) before some execve commands execute. But I refer to the proroot code now and it doesn t seem to take effect. If the parameters are not modified, the program will print the content normally, but if the parameter is modified, the program will not print any information. I tried to reconstruct the logic of enter.c in execve, which is the code I modified:

//int execve(const char *pathname, char *const argv[], char *const envp[]);
        case SC_execve: {
            status = 0;
            if (getRuntimeIsFinsh()) {
                char org_path_buff[PATH_MAX];
                get_sysarg_path(tracee, org_path_buff, SYSARG_1);

                ArrayOfXPointers *args_array;
                fetch_array_of_xpointers(tracee, &args_array, SYSARG_2, 0);
                string orig_args, orig_cmd_path(org_path_buff);
                size_t args_count = args_array->length;
                for (size_t i = 0; i < args_count - 1; i++) {
                    char *arg_str;
                    read_xpointee_as_string_t(tracee, args_array, i, &arg_str);
                    if (i != 0) {
                        orig_args.append(" ");
                    }
                    orig_args.append(arg_str);
                    
                }
                //get mock value 
                auto handler_info = ZhenxiRunTime::handlerExecve::handler(orig_args);
                
                if (handler_info.isHandler) {
                    //set cmd path 
                    set_sysarg_path(tracee, handler_info.cmd_path.c_str(), SYSARG_1);

                    vector<string> new_args_list = handler_info.args;
                    resize_array_of_xpointers(args_array, 0, (ssize_t) (new_args_list.size() + 1));

                    for (size_t i = 0; i < new_args_list.size(); i++) {
                        write_xpointee(args_array, i, new_args_list[i].c_str());
                    }
                    //nullptr
                    write_xpointee(args_array, new_args_list.size(), nullptr);
					//set args 
                    status = push_array_of_xpointers_t(tracee, args_array, SYSARG_2);
                    if (status < 0) {
                        LOGE("svc execve error  push_array_of_xpointers %d", status);
                        break;
                    }
                }
            }
            break;
        }

This is the code that I tested, and the main purpose is to replace the return value of [stat-f /], with [cat my_file_path]

    const char *logcatPath = "/system/bin/stat";
    const char *logcatArgs[] = { "stat", "-f", "/", nullptr,"111","222" };
    int pipefd[2];
    if (pipe(pipefd) == -1) {
        LOGE("pipe error")
        return;
    }
    pid_t pid = fork();
    if (pid < 0) {
        LOGE("fork");
        return;
    } else if (pid == 0) {
        
        close(pipefd[0]); 
        dup2(pipefd[1], STDOUT_FILENO);
        dup2(pipefd[1], STDERR_FILENO);
        close(pipefd[1]); 

        //int ret = (int)syscall(__NR_execve,logcatPath, (char *const *)logcatArgs, nullptr);
        int ret = execve(logcatPath, (char *const *)logcatArgs, nullptr);

        if (ret < 0) {
            LOGE("test execve error ret < 0 %s  ", strerror(errno))
            _exit(EXIT_FAILURE);
        }
        LOGE("test execve success ret %d",ret)
    } else {
        
        close(pipefd[1]);
        
        char buffer[1024];
        ssize_t bytesRead;
        //read
        while ((bytesRead = read(pipefd[0], buffer, sizeof(buffer) - 1)) > 0) {
            buffer[bytesRead] = '\0';
            LOGE("test execve printf ->  %s", buffer)
            //break;
        }
        close(pipefd[0]); 
        int status;
        waitpid(pid, &status, 0);
    }

The problem now is that as long as I make a parameter modification and replacement

LOGE("test execve printf ->  %s", buffer)

This log will not be printed, the program does not have any translation, if it is ok, I tried to change the stat command to [cat my_file_path] or [sh-c 'cat my_file_path'], I don't know how to solve this problem. Can you help me with something? Great developer