1 | /* |
---|
2 | * linux/arch/i386/kernel/ioport.c |
---|
3 | * |
---|
4 | * This contains the io-permission bitmap code - written by obz, with changes |
---|
5 | * by Linus. |
---|
6 | */ |
---|
7 | |
---|
8 | #include <linux/sched.h> |
---|
9 | #include <linux/kernel.h> |
---|
10 | #include <linux/capability.h> |
---|
11 | #include <linux/errno.h> |
---|
12 | #include <linux/types.h> |
---|
13 | #include <linux/ioport.h> |
---|
14 | #include <linux/smp.h> |
---|
15 | #include <linux/smp_lock.h> |
---|
16 | #include <linux/stddef.h> |
---|
17 | #include <linux/slab.h> |
---|
18 | #include <linux/thread_info.h> |
---|
19 | #include <xen/interface/physdev.h> |
---|
20 | |
---|
21 | /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ |
---|
22 | static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value) |
---|
23 | { |
---|
24 | unsigned long mask; |
---|
25 | unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG); |
---|
26 | unsigned int low_index = base & (BITS_PER_LONG-1); |
---|
27 | int length = low_index + extent; |
---|
28 | |
---|
29 | if (low_index != 0) { |
---|
30 | mask = (~0UL << low_index); |
---|
31 | if (length < BITS_PER_LONG) |
---|
32 | mask &= ~(~0UL << length); |
---|
33 | if (new_value) |
---|
34 | *bitmap_base++ |= mask; |
---|
35 | else |
---|
36 | *bitmap_base++ &= ~mask; |
---|
37 | length -= BITS_PER_LONG; |
---|
38 | } |
---|
39 | |
---|
40 | mask = (new_value ? ~0UL : 0UL); |
---|
41 | while (length >= BITS_PER_LONG) { |
---|
42 | *bitmap_base++ = mask; |
---|
43 | length -= BITS_PER_LONG; |
---|
44 | } |
---|
45 | |
---|
46 | if (length > 0) { |
---|
47 | mask = ~(~0UL << length); |
---|
48 | if (new_value) |
---|
49 | *bitmap_base++ |= mask; |
---|
50 | else |
---|
51 | *bitmap_base++ &= ~mask; |
---|
52 | } |
---|
53 | } |
---|
54 | |
---|
55 | |
---|
56 | /* |
---|
57 | * this changes the io permissions bitmap in the current task. |
---|
58 | */ |
---|
59 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) |
---|
60 | { |
---|
61 | struct thread_struct * t = ¤t->thread; |
---|
62 | unsigned long *bitmap; |
---|
63 | struct physdev_set_iobitmap set_iobitmap; |
---|
64 | |
---|
65 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) |
---|
66 | return -EINVAL; |
---|
67 | if (turn_on && !capable(CAP_SYS_RAWIO)) |
---|
68 | return -EPERM; |
---|
69 | |
---|
70 | /* |
---|
71 | * If it's the first ioperm() call in this thread's lifetime, set the |
---|
72 | * IO bitmap up. ioperm() is much less timing critical than clone(), |
---|
73 | * this is why we delay this operation until now: |
---|
74 | */ |
---|
75 | if (!t->io_bitmap_ptr) { |
---|
76 | bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
---|
77 | if (!bitmap) |
---|
78 | return -ENOMEM; |
---|
79 | |
---|
80 | memset(bitmap, 0xff, IO_BITMAP_BYTES); |
---|
81 | t->io_bitmap_ptr = bitmap; |
---|
82 | set_thread_flag(TIF_IO_BITMAP); |
---|
83 | |
---|
84 | set_xen_guest_handle(set_iobitmap.bitmap, (char *)bitmap); |
---|
85 | set_iobitmap.nr_ports = IO_BITMAP_BITS; |
---|
86 | HYPERVISOR_physdev_op(PHYSDEVOP_set_iobitmap, &set_iobitmap); |
---|
87 | } |
---|
88 | |
---|
89 | set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); |
---|
90 | |
---|
91 | return 0; |
---|
92 | } |
---|
93 | |
---|
94 | /* |
---|
95 | * sys_iopl has to be used when you want to access the IO ports |
---|
96 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped |
---|
97 | * you'd need 8kB of bitmaps/process, which is a bit excessive. |
---|
98 | * |
---|
99 | * Here we just change the eflags value on the stack: we allow |
---|
100 | * only the super-user to do it. This depends on the stack-layout |
---|
101 | * on system-call entry - see also fork() and the signal handling |
---|
102 | * code. |
---|
103 | */ |
---|
104 | |
---|
105 | asmlinkage long sys_iopl(unsigned long unused) |
---|
106 | { |
---|
107 | volatile struct pt_regs * regs = (struct pt_regs *) &unused; |
---|
108 | unsigned int level = regs->ebx; |
---|
109 | struct thread_struct *t = ¤t->thread; |
---|
110 | unsigned int old = (t->iopl >> 12) & 3; |
---|
111 | |
---|
112 | if (level > 3) |
---|
113 | return -EINVAL; |
---|
114 | /* Trying to gain more privileges? */ |
---|
115 | if (level > old) { |
---|
116 | if (!capable(CAP_SYS_RAWIO)) |
---|
117 | return -EPERM; |
---|
118 | } |
---|
119 | t->iopl = level << 12; |
---|
120 | set_iopl_mask(t->iopl); |
---|
121 | return 0; |
---|
122 | } |
---|