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
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
/*
* This contains the io-permission bitmap code - written by obz, with changes
* by Linus. 32/64 bits code unification by Miguel Botón.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/thread_info.h>
#include <linux/syscalls.h>
#include <asm/syscalls.h>
/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
static void set_bitmap(unsigned long *bitmap, unsigned int base,
unsigned int extent, int new_value)
{
unsigned int i;
for (i = base; i < base + extent; i++) {
if (new_value)
__set_bit(i, bitmap);
else
__clear_bit(i, bitmap);
}
}
/*
* this changes the io permissions bitmap in the current task.
*/
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
struct thread_struct * t = ¤t->thread;
struct tss_struct * tss;
unsigned int i, max_long, bytes, bytes_updated;
if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
return -EINVAL;
if (turn_on && !capable(CAP_SYS_RAWIO))
return -EPERM;
/*
* If it's the first ioperm() call in this thread's lifetime, set the
* IO bitmap up. ioperm() is much less timing critical than clone(),
* this is why we delay this operation until now:
*/
if (!t->io_bitmap_ptr) {
unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
if (!bitmap)
return -ENOMEM;
memset(bitmap, 0xff, IO_BITMAP_BYTES);
t->io_bitmap_ptr = bitmap;
set_thread_flag(TIF_IO_BITMAP);
}
/*
* do it in the per-thread copy and in the TSS ...
*
* Disable preemption via get_cpu() - we must not switch away
* because the ->io_bitmap_max value must match the bitmap
* contents:
*/
tss = &per_cpu(init_tss, get_cpu());
set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
/*
* Search for a (possibly new) maximum. This is simple and stupid,
* to keep it obviously correct:
*/
max_long = 0;
for (i = 0; i < IO_BITMAP_LONGS; i++)
if (t->io_bitmap_ptr[i] != ~0UL)
max_long = i;
bytes = (max_long + 1) * sizeof(unsigned long);
bytes_updated = max(bytes, t->io_bitmap_max);
t->io_bitmap_max = bytes;
#ifdef CONFIG_X86_32
/*
* Sets the lazy trigger so that the next I/O operation will
* reload the correct bitmap.
* Reset the owner so that a process switch will not set
* tss->io_bitmap_base to IO_BITMAP_OFFSET.
*/
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
tss->io_bitmap_owner = NULL;
#else
/* Update the TSS: */
memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
#endif
put_cpu();
return 0;
}
/*
* 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 flags 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.
*/
static int do_iopl(unsigned int level, struct pt_regs *regs)
{
unsigned int old = (regs->flags >> 12) & 3;
if (level > 3)
return -EINVAL;
/* Trying to gain more privileges? */
if (level > old) {
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
}
regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
return 0;
}
#ifdef CONFIG_X86_32
asmlinkage long sys_iopl(unsigned long regsp)
{
struct pt_regs *regs = (struct pt_regs *)®sp;
unsigned int level = regs->bx;
struct thread_struct *t = ¤t->thread;
int rc;
rc = do_iopl(level, regs);
if (rc < 0)
goto out;
t->iopl = level << 12;
set_iopl_mask(t->iopl);
out:
return rc;
}
#else
asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
{
return do_iopl(level, regs);
}
#endif
|
