如何拦截dlopen()中的文件系统访问？

#include<stdio.h>
#include <unistd.h>
#include <sys/prctl.h>
#include<linux/seccomp.h>
#include<linux/filter.h>
#include <dlfcn.h>

int main() {
    // 设置seccomp过滤器，只允许访问read、write、exit等系统调用
    struct sock_filter filter[] = {
        BPF_STMT(BPF_LD+BPF_W+BPF_ABS, offsetof(struct seccomp_data, nr)),
        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_read, 0, 1),
        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_write, 0, 1),
        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_exit, 0, 1),
        BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL),
        BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
    };
    struct sock_fprog prog = {
        .len = sizeof(filter)/sizeof(filter[0]),
        .filter = filter,
    };
    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1) {
        perror("prctl");
        return 1;
    }
    if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) == -1) {
        perror("prctl");
        return 1;
    }

    // 调用dlopen()
    void *handle = dlopen("libtest.so", RTLD_LAZY);
    if (!handle) {
        fprintf(stderr, "dlopen failed: %s\n", dlerror());
        return 1;
    }

    // 清理seccomp过滤器
    struct sock_filter clear_filter[] = {
        BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW),
    };
    struct sock_fprog clear_prog = {
        .len = sizeof(clear_filter)/sizeof(clear_filter[0]),
        .filter = clear_filter,
    };
    if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &clear_prog) == -1) {
        perror("prctl");
        return 1;
    }

    return 0;
}

#include<stdio.h>
#include <stdlib.h>
#include <dlfcn.h>

void *dlopen(const char *filename, int flag) {
    fprintf(stderr, "dlopen() called with filename=%s\n", filename);
    return NULL;
}

int main() {
    // 设置LD_PRELOAD环境变量，使得dlopen()调用我们自己的实现
    setenv("LD_PRELOAD", "./libpreload.so", 1);

    // 调用dlopen()
    void *handle = dlopen("libtest.so", RTLD_LAZY);
    if (!handle) {
        fprintf(stderr, "dlopen failed: %s\n", dlerror());
        return 1;
    }

    return 0;
}

#include<stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/reg.h>

int main() {
    pid_t pid = fork();
    if (pid == 0) {
        // 子进程中调用dlopen()
        void *handle = dlopen("libtest.so", RTLD_LAZY);
        if (!handle) {
            fprintf(stderr, "dlopen failed: %s\n", dlerror());
            exit(1);
        }
        exit(0);
    } else if (pid > 0) {
        // 父进程中使用ptrace跟踪子进程
        int status;
        while (1) {
            waitpid(pid, &status, 0);
            if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) {
                // 如果子进程停止是因为遇到了断点，则继续执行
                ptrace(PTRACE_CONT, pid, NULL, NULL);
            } else if (WIFEXITED(status)) {
                // 如果子进程已经退出，则退出
                break;
            } else {
                // 其他情况下，打印一条消息并继续执行
                fprintf(stderr, "unknown status: %d\n", status);
                ptrace(PTRACE_CONT, pid, NULL, NULL);
            }
        }
    } else {
        perror("fork");
        return 1;
    }

    return 0;
}