1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
/*
* linux/arch/i386/kernel/ioport.c
*
* This contains the io-permission bitmap code - written by obz, with changes
* by Linus.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
static void set_bitmap(unsigned long *bitmap, short base, short extent, int new_value)
{
int mask;
unsigned long *bitmap_base = bitmap + (base >> 5);
unsigned short low_index = base & 0x1f;
int length = low_index + extent;
if (low_index != 0) {
mask = (~0 << low_index);
if (length < 32)
mask &= ~(~0 << length);
if (new_value)
*bitmap_base++ |= mask;
else
*bitmap_base++ &= ~mask;
length -= 32;
}
mask = (new_value ? ~0 : 0);
while (length >= 32) {
*bitmap_base++ = mask;
length -= 32;
}
if (length > 0) {
mask = ~(~0 << length);
if (new_value)
*bitmap_base++ |= mask;
else
*bitmap_base++ &= ~mask;
}
}
/*
* this changes the io permissions bitmap in the current task.
*/
asmlinkage int sys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
if ((from + num <= from) || (from + num > IO_BITMAP_SIZE*32))
return -EINVAL;
if (!suser())
return -EPERM;
set_bitmap((unsigned long *)current->tss.io_bitmap, from, num, !turn_on);
return 0;
}
unsigned int *stack;
/*
* sys_iopl has to be used when you want to access the IO ports
* beyond the 0x3ff range: to get the full 65536 ports bitmapped
* you'd need 8kB of bitmaps/process, which is a bit excessive.
*
* Here we just change the eflags value on the stack: we allow
* only the super-user to do it. This depends on the stack-layout
* on system-call entry - see also fork() and the signal handling
* code.
*/
asmlinkage int sys_iopl(long ebx,long ecx,long edx,
long esi, long edi, long ebp, long eax, long ds,
long es, long orig_eax, long eip, long cs,
long eflags, long esp, long ss)
{
unsigned int level = ebx;
if (level > 3)
return -EINVAL;
if (!suser())
return -EPERM;
*(&eflags) = (eflags & 0xffffcfff) | (level << 12);
return 0;
}
|
