Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * This contains the io-permission bitmap code - written by obz, with changes |
3 | * by Linus. | |
4 | */ | |
5 | ||
6 | #include <linux/sched.h> | |
7 | #include <linux/kernel.h> | |
a9415644 | 8 | #include <linux/capability.h> |
1da177e4 LT |
9 | #include <linux/errno.h> |
10 | #include <linux/types.h> | |
11 | #include <linux/ioport.h> | |
12 | #include <linux/smp.h> | |
1da177e4 LT |
13 | #include <linux/stddef.h> |
14 | #include <linux/slab.h> | |
15 | #include <linux/thread_info.h> | |
ca906e42 | 16 | #include <linux/syscalls.h> |
1da177e4 LT |
17 | |
18 | /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ | |
19 | static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value) | |
20 | { | |
21 | int i; | |
22 | if (new_value) | |
23 | for (i = base; i < base + extent; i++) | |
24 | __set_bit(i, bitmap); | |
25 | else | |
26 | for (i = base; i < base + extent; i++) | |
27 | clear_bit(i, bitmap); | |
28 | } | |
29 | ||
30 | /* | |
31 | * this changes the io permissions bitmap in the current task. | |
32 | */ | |
33 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) | |
34 | { | |
35 | unsigned int i, max_long, bytes, bytes_updated; | |
36 | struct thread_struct * t = ¤t->thread; | |
37 | struct tss_struct * tss; | |
38 | unsigned long *bitmap; | |
39 | ||
40 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) | |
41 | return -EINVAL; | |
42 | if (turn_on && !capable(CAP_SYS_RAWIO)) | |
43 | return -EPERM; | |
44 | ||
45 | /* | |
46 | * If it's the first ioperm() call in this thread's lifetime, set the | |
47 | * IO bitmap up. ioperm() is much less timing critical than clone(), | |
48 | * this is why we delay this operation until now: | |
49 | */ | |
50 | if (!t->io_bitmap_ptr) { | |
51 | bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); | |
52 | if (!bitmap) | |
53 | return -ENOMEM; | |
54 | ||
55 | memset(bitmap, 0xff, IO_BITMAP_BYTES); | |
56 | t->io_bitmap_ptr = bitmap; | |
d3a4f48d | 57 | set_thread_flag(TIF_IO_BITMAP); |
1da177e4 LT |
58 | } |
59 | ||
60 | /* | |
61 | * do it in the per-thread copy and in the TSS ... | |
62 | * | |
63 | * Disable preemption via get_cpu() - we must not switch away | |
64 | * because the ->io_bitmap_max value must match the bitmap | |
65 | * contents: | |
66 | */ | |
67 | tss = &per_cpu(init_tss, get_cpu()); | |
68 | ||
69 | set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); | |
70 | ||
71 | /* | |
72 | * Search for a (possibly new) maximum. This is simple and stupid, | |
73 | * to keep it obviously correct: | |
74 | */ | |
75 | max_long = 0; | |
76 | for (i = 0; i < IO_BITMAP_LONGS; i++) | |
77 | if (t->io_bitmap_ptr[i] != ~0UL) | |
78 | max_long = i; | |
79 | ||
80 | bytes = (max_long + 1) * sizeof(long); | |
81 | bytes_updated = max(bytes, t->io_bitmap_max); | |
82 | ||
83 | t->io_bitmap_max = bytes; | |
84 | ||
85 | /* Update the TSS: */ | |
86 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); | |
87 | ||
88 | put_cpu(); | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | /* | |
94 | * sys_iopl has to be used when you want to access the IO ports | |
95 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped | |
96 | * you'd need 8kB of bitmaps/process, which is a bit excessive. | |
97 | * | |
65ea5b03 | 98 | * Here we just change the flags value on the stack: we allow |
1da177e4 LT |
99 | * only the super-user to do it. This depends on the stack-layout |
100 | * on system-call entry - see also fork() and the signal handling | |
101 | * code. | |
102 | */ | |
103 | ||
104 | asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs) | |
105 | { | |
65ea5b03 | 106 | unsigned int old = (regs->flags >> 12) & 3; |
1da177e4 LT |
107 | |
108 | if (level > 3) | |
109 | return -EINVAL; | |
110 | /* Trying to gain more privileges? */ | |
111 | if (level > old) { | |
112 | if (!capable(CAP_SYS_RAWIO)) | |
113 | return -EPERM; | |
114 | } | |
65ea5b03 | 115 | regs->flags = (regs->flags &~ X86_EFLAGS_IOPL) | (level << 12); |
1da177e4 LT |
116 | return 0; |
117 | } |