albcamus albcamus 当前离线 当前离线 大富大贵 大富大贵, 积分 12886, 距离下一级还需 7114 积分 好友

博客

消息 论坛徽章: 0

电梯直达 1楼 [收藏( 0 )] [报告] 发表于 2007-01-18 18:08 | 只看该作者 | 倒序浏览 发表于 2007-01-18 18:08 #include <linux/kernel.h>

#include <linux/init.h>

#include <linux/module.h>

#include <asm/uaccess.h>

#include <asm/fcntl.h>

#include <asm/unistd.h>

#include <asm/ia32_unistd.h>

#include <asm/msr.h>







#define THIS_DESCRIPTION "Dynamically get sys_call_table/ia32_sys_call_table in kernel module.

\t\tI don't think there would be anyone who won't enable CONFIG_IA32_EMULATION these days.

\t\tso you can add the unessary check if you really want to."

MODULE_DESCRIPTION( THIS_DESCRIPTION );

MODULE_AUTHOR("albcamus <albcamus@gmail.com>");

MODULE_LICENSE("GPL");





/**

* TODO: if you want shut this up, comment the following line.

*/

#define BY_IDT_DEBUG



#ifdef BY_IDT_DEBUG

#define dbgprint(format,args...) \

printk("get_syscall: function:%s-L%d: "format, __FUNCTION__, __LINE__, ## args);

#else

#define dbgprint(format,args...) do {} while(0);

#endif





/**

* sys call table

*/

void ** my_ia32_syscall_table;

void ** my_syscall_table;







/**

* 10 bytes -- please refer to AMD64 Architecture Programmer's

* Manuals for more information.

*/

struct idtr {

unsigned short limit;

unsigned long base; //in 64bit mode, base address is 8 bytes

} __attribute__ ((packed));





/**

* in long mode -- 64bit mode and compatity mode,

* every IDT entry has a 16-byte size

*/

struct idt {

u16 offset_low;

u16 segment;

unsigned ist : 3, zero0 : 5, type : 5, dpl :2, p : 1;

u16 offset_middle;

u32 offset_high;

u32 zero1;

} __attribute__ ((packed));









/**

* Return the first appearence of NEEDLE in HAYSTACK. -- copied from PHRACK

* */

static void *memmem(const void *haystack, size_t haystack_len,

const void *needle, size_t needle_len)

{/*{{{*/

const char *begin;

const char *const last_possible

= (const char *) haystack + haystack_len - needle_len;



if (needle_len == 0)

/* The first occurrence of the empty string is deemed to occur at

the beginning of the string. */

return (void *) haystack;



/* Sanity check, otherwise the loop might search through the whole

memory. */

if (__builtin_expect(haystack_len < needle_len, 0))

return NULL;



for (begin = (const char *) haystack; begin <= last_possible;

++begin)

if (begin[0] == ((const char *) needle)[0]

&& !memcmp((const void *) &begin[1],

(const void *) ((const char *) needle + 1),

needle_len - 1))

return (void *) begin;



return NULL;

}/*}}}*/





/**

* Find the location of ia32_sys_call_table

*/

static unsigned long get_syscall_table_ia32(void)

{/*{{{*/

#define OFFSET_SYSCALL 100 /* from system_call/ia32_syscall, we'll read first 150 bytes */



struct idtr idtr;

struct idt idt;



unsigned long sys_call_off;

unsigned long retval;



char sc_asm[OFFSET_SYSCALL], *p;









/* well, let's read IDTR */

asm("sidt %0"

:"=m"(idtr)

: );



dbgprint("idtr base at %p

", (void *)idtr.base);



/**

* Read in IDT for vector 0x80 (syscall)

*/

memcpy(&idt, (char *) idtr.base + 16 * 0x80, sizeof(idt));

sys_call_off = ( ( (unsigned long)idt.offset_high ) << 32 ) |

( ((idt.offset_middle << 16 ) | idt.offset_low) & 0x00000000ffffffff );

dbgprint("sys_call_off at %p

", (void *)sys_call_off);



/* we have syscall routine address now, look for syscall table

dispatch (indirect call) */

memcpy(sc_asm, (void *)sys_call_off, OFFSET_SYSCALL);

/**

* ia32_call > ia32_tracesys > ia32_do_syscall > 'call *ia32_sys_call_table(,%rax,8)'

* Find callq *ia32_sys_call_table(,%rax,8)

*

* (gdb) disassemble ia32_syscall

* Dump of assembler code for function ia32_syscall:

* 0xffffffff81066b98 <ia32_syscall+0>: swapgs

* 0xffffffff81066b9b <ia32_syscall+3>: sti

* 0xffffffff81066b9c <ia32_syscall+4>: mov %eax,%eax

* 0xffffffff81066b9e <ia32_syscall+6>: push %rax

* 0xffffffff81066b9f <ia32_syscall+7>: cld

* 0xffffffff81066ba0 <ia32_syscall+8>: sub $0x48,%rsp

* 0xffffffff81066ba4 <ia32_syscall+12>: mov %rdi,0x40(%rsp)

* 0xffffffff81066ba9 <ia32_syscall+17>: mov %rsi,0x38(%rsp)

* 0xffffffff81066bae <ia32_syscall+22>: mov %rdx,0x30(%rsp)

* 0xffffffff81066bb3 <ia32_syscall+27>: mov %rcx,0x28(%rsp)

* 0xffffffff81066bb8 <ia32_syscall+32>: mov %rax,0x20(%rsp)

* 0xffffffff81066bbd <ia32_syscall+37>: mov %gs:0x10,%r10

* 0xffffffff81066bc6 <ia32_syscall+46>: sub $0x1fd8,%r10

* 0xffffffff81066bcd <ia32_syscall+53>: orl $0x2,0x14(%r10)

* 0xffffffff81066bd2 <ia32_syscall+58>: testl $0x181,0x10(%r10)

* 0xffffffff81066bda <ia32_syscall+66>: jne 0xffffffff81066c04 <ia32_tracesys>

* End of assembler dump.

* (gdb) disassemble ia32_tracesys

* Dump of assembler code for function ia32_tracesys:

* 0xffffffff81066c04 <ia32_tracesys+0>: sub $0x30,%rsp

* 0xffffffff81066c08 <ia32_tracesys+4>: mov %rbx,0x28(%rsp)

* 0xffffffff81066c0d <ia32_tracesys+9>: mov %rbp,0x20(%rsp)

* 0xffffffff81066c12 <ia32_tracesys+14>: mov %r12,0x18(%rsp)

* 0xffffffff81066c17 <ia32_tracesys+19>: mov %r13,0x10(%rsp)

* 0xffffffff81066c1c <ia32_tracesys+24>: mov %r14,0x8(%rsp)

* 0xffffffff81066c21 <ia32_tracesys+29>: mov %r15,(%rsp)

* 0xffffffff81066c25 <ia32_tracesys+33>: movq $0xffffffffffffffda,0x50(%rsp)

* 0xffffffff81066c2e <ia32_tracesys+42>: mov %rsp,%rdi

* 0xffffffff81066c31 <ia32_tracesys+45>: callq 0xffffffff81073a02 <syscall_trace_enter>

* 0xffffffff81066c36 <ia32_tracesys+50>: mov 0x30(%rsp),%r11

* 0xffffffff81066c3b <ia32_tracesys+55>: mov 0x38(%rsp),%r10

* 0xffffffff81066c40 <ia32_tracesys+60>: mov 0x40(%rsp),%r9

* 0xffffffff81066c45 <ia32_tracesys+65>: mov 0x48(%rsp),%r8

* 0xffffffff81066c4a <ia32_tracesys+70>: mov 0x58(%rsp),%rcx

* 0xffffffff81066c4f <ia32_tracesys+75>: mov 0x60(%rsp),%rdx

* 0xffffffff81066c54 <ia32_tracesys+80>: mov 0x68(%rsp),%rsi

* 0xffffffff81066c59 <ia32_tracesys+85>: mov 0x70(%rsp),%rdi

* 0xffffffff81066c5e <ia32_tracesys+90>: mov 0x78(%rsp),%rax

* 0xffffffff81066c63 <ia32_tracesys+95>: mov (%rsp),%r15

* 0xffffffff81066c67 <ia32_tracesys+99>: mov 0x8(%rsp),%r14

* 0xffffffff81066c6c <ia32_tracesys+104>: mov 0x10(%rsp),%r13

* 0xffffffff81066c71 <ia32_tracesys+109>: mov 0x18(%rsp),%r12

* 0xffffffff81066c76 <ia32_tracesys+114>: mov 0x20(%rsp),%rbp

* 0xffffffff81066c7b <ia32_tracesys+119>: mov 0x28(%rsp),%rbx

* 0xffffffff81066c80 <ia32_tracesys+124>: add $0x30,%rsp

* 0xffffffff81066c84 <ia32_tracesys+128>: jmpq 0xffffffff81066bdc <ia32_do_syscall>

* End of assembler dump.

* (gdb) disassemble ia32_do_syscall

* Dump of assembler code for function ia32_do_syscall:

* 0xffffffff81066bdc <ia32_do_syscall+0>: cmp $0x13d,%eax

* 0xffffffff81066be1 <ia32_do_syscall+5>: ja 0xffffffff81066c89 <ia32_badsys>

* 0xffffffff81066be7 <ia32_do_syscall+11>: mov %edi,%r8d

* 0xffffffff81066bea <ia32_do_syscall+14>: mov %ebp,%r9d

* 0xffffffff81066bed <ia32_do_syscall+17>: xchg %ecx,%esi

* 0xffffffff81066bef <ia32_do_syscall+19>: mov %ebx,%edi

* 0xffffffff81066bf1 <ia32_do_syscall+21>: mov %edx,%edx

* 0xffffffff81066bf3 <ia32_do_syscall+23>: callq *0xffffffff812e7c70(,%rax,8)

* End of assembler dump.

* (gdb) x/xw ia32_do_syscall+23

* 0xffffffff81066bf3 <ia32_do_syscall+23>: 0x70c514ff

* (gdb)

*

*/

p = (char *) memmem(sc_asm, OFFSET_SYSCALL, "\xff\x14\xc5", 3);

if (p == NULL) {

printk("opcode not found, meats that we cannot find sys_call_table.

");

return 0;

}



retval = *(unsigned long *) (p + 3);

return retval;

#undef OFFSET_SYSCALL

}/*}}}*/





/**

* Find the location of long-mode sys_call_table

*/

static unsigned long get_syscall_table_long(void)

{/*{{{*/

#define OFFSET_SYSCALL 150

unsigned long syscall_long, retval;

char sc_asm[OFFSET_SYSCALL];



rdmsrl(MSR_LSTAR, syscall_long);

dbgprint("long mode: system_call is at %p

", (void *)syscall_long);



memcpy(sc_asm, (char *)syscall_long, OFFSET_SYSCALL);





/**

* Find callq *sys_call_table(,%rax,8)

* -------------------------------------

* (gdb) disassemble system_call

* Dump of assembler code for function system_call:

* 0xffffffff81063750 <system_call+0>: swapgs

* 0xffffffff81063753 <system_call+3>: mov %rsp,%gs:0x18

* 0xffffffff8106375c <system_call+12>: mov %gs:0x10,%rsp

* 0xffffffff81063765 <system_call+21>: sti

* 0xffffffff81063766 <system_call+22>: sub $0x50,%rsp

* 0xffffffff8106376a <system_call+26>: mov %rdi,0x40(%rsp)

* 0xffffffff8106376f <system_call+31>: mov %rsi,0x38(%rsp)

* 0xffffffff81063774 <system_call+36>: mov %rdx,0x30(%rsp)

* 0xffffffff81063779 <system_call+41>: mov %rax,0x20(%rsp)

* 0xffffffff8106377e <system_call+46>: mov %r8,0x18(%rsp)

* 0xffffffff81063783 <system_call+51>: mov %r9,0x10(%rsp)

* 0xffffffff81063788 <system_call+56>: mov %r10,0x8(%rsp)

* 0xffffffff8106378d <system_call+61>: mov %r11,(%rsp)

* 0xffffffff81063791 <system_call+65>: mov %rax,0x48(%rsp)

* 0xffffffff81063796 <system_call+70>: mov %rcx,0x50(%rsp)

* 0xffffffff8106379b <system_call+75>: mov %gs:0x10,%rcx

* 0xffffffff810637a4 <system_call+84>: sub $0x1fd8,%rcx

* 0xffffffff810637ab <system_call+91>: testl $0x181,0x10(%rcx)

* 0xffffffff810637b2 <system_call+98>: jne 0xffffffff81063889 <tracesys>

* 0xffffffff810637b8 <system_call+104>: cmp $0x117,%rax

* 0xffffffff810637be <system_call+110>: ja 0xffffffff8106387b <badsys>

* 0xffffffff810637c4 <system_call+116>: mov %r10,%rcx

* 0xffffffff810637c7 <system_call+119>: callq *0xffffffff812e6d60(,%rax,8)

* 0xffffffff810637ce <system_call+126>: mov %rax,0x20(%rsp)

* End of assembler dump.

* (gdb) x/xw system_call+119

* 0xffffffff810637c7 <system_call+119>: 0x60c514ff

* (gdb)

*/

retval = (unsigned long) memmem(sc_asm, OFFSET_SYSCALL, "\xff\x14\xc5", 3);

if ( retval != 0 ) {

dbgprint("long mode : sys_call_table is at %p

",

(void *) (* (unsigned long *)(retval+3)) ) ;

retval = (unsigned long) ( * (unsigned long *)(retval+3) );

} else {

printk("long mode : memmem found nothing, returning NULL:(

");

retval = 0;

}



#undef OFFSET_SYSCALL

return retval;

}/*}}}*/









static int get_syscall_init_module(void)

{/*{{{*/

printk(KERN_DEBUG "get_syscall: Hi, you fucking linux!

");



my_ia32_syscall_table = (void **) get_syscall_table_ia32();

if (my_ia32_syscall_table == 0)

return -1;



my_syscall_table = (void **) get_syscall_table_long();

if (my_syscall_table == 0)

return -1;



dbgprint("ia32_sys_call_table address : %p

", (void *) my_ia32_syscall_table);

dbgprint("long mode : sys_call_table address : %p

", (void *) my_syscall_table);



#define REPLACE_IA32(x) o_sys_##x = my_ia32_syscall_table[__NR_ia32_##x];\

my_ia32_syscall_table[__NR_ia32_##x] = my_sys_##x



#define GET_OLD_IA32_SYSCALL_ADDR(x) my_ia32_syscall_table[__NR_ia32_##x]

// dbgprint("sys_read at %p, my_read at %p

", (void *)GET_OLD_IA32_SYSCALL_ADDR(read), (void *)my_sys_read);



// REPLACE_IA32(read);

#undef REPLACE_IA32





return 0;

}/*}}}*/





static void get_syscall_exit_module(void)

{/*{{{*/

printk(KERN_DEBUG "get_syscall: bye, you fucking linux!

");



#define RESTORE_IA32(x) my_ia32_syscall_table[__NR_ia32_##x] = o_sys_##x



// RESTORE_IA32(read);



#undef RESTORE_IA32

}/*}}}*/



module_init(get_syscall_init_module);

module_exit(get_syscall_exit_module); 复制代码







Reference :

http://phrack.org/archives/58/p58-0x07



[ 本帖最后由 albcamus 于 2007-1-19 09:33 编辑 ]