Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 | 2 | * This contains the io-permission bitmap code - written by obz, with changes |
ccafa59a | 3 | * by Linus. 32/64 bits code unification by Miguel Botón. |
1da177e4 LT |
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> |
da1016df | 17 | #include <linux/bitmap.h> |
bbc1f698 | 18 | #include <asm/syscalls.h> |
1da177e4 | 19 | |
1da177e4 LT |
20 | /* |
21 | * this changes the io permissions bitmap in the current task. | |
22 | */ | |
23 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) | |
24 | { | |
5866e1b4 JSR |
25 | struct thread_struct *t = ¤t->thread; |
26 | struct tss_struct *tss; | |
ccafa59a | 27 | unsigned int i, max_long, bytes, bytes_updated; |
1da177e4 LT |
28 | |
29 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) | |
30 | return -EINVAL; | |
31 | if (turn_on && !capable(CAP_SYS_RAWIO)) | |
32 | return -EPERM; | |
33 | ||
34 | /* | |
35 | * If it's the first ioperm() call in this thread's lifetime, set the | |
36 | * IO bitmap up. ioperm() is much less timing critical than clone(), | |
37 | * this is why we delay this operation until now: | |
38 | */ | |
39 | if (!t->io_bitmap_ptr) { | |
9a211abe TG |
40 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
41 | ||
1da177e4 LT |
42 | if (!bitmap) |
43 | return -ENOMEM; | |
44 | ||
45 | memset(bitmap, 0xff, IO_BITMAP_BYTES); | |
46 | t->io_bitmap_ptr = bitmap; | |
b3cf2576 | 47 | set_thread_flag(TIF_IO_BITMAP); |
1da177e4 LT |
48 | } |
49 | ||
50 | /* | |
51 | * do it in the per-thread copy and in the TSS ... | |
52 | * | |
53 | * Disable preemption via get_cpu() - we must not switch away | |
54 | * because the ->io_bitmap_max value must match the bitmap | |
55 | * contents: | |
56 | */ | |
57 | tss = &per_cpu(init_tss, get_cpu()); | |
58 | ||
da1016df AM |
59 | if (turn_on) |
60 | bitmap_clear(t->io_bitmap_ptr, from, num); | |
61 | else | |
62 | bitmap_set(t->io_bitmap_ptr, from, num); | |
1da177e4 LT |
63 | |
64 | /* | |
65 | * Search for a (possibly new) maximum. This is simple and stupid, | |
66 | * to keep it obviously correct: | |
67 | */ | |
68 | max_long = 0; | |
69 | for (i = 0; i < IO_BITMAP_LONGS; i++) | |
70 | if (t->io_bitmap_ptr[i] != ~0UL) | |
71 | max_long = i; | |
72 | ||
ccafa59a | 73 | bytes = (max_long + 1) * sizeof(unsigned long); |
74 | bytes_updated = max(bytes, t->io_bitmap_max); | |
1da177e4 | 75 | |
ccafa59a | 76 | t->io_bitmap_max = bytes; |
77 | ||
ccafa59a | 78 | /* Update the TSS: */ |
79 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); | |
1da177e4 LT |
80 | |
81 | put_cpu(); | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | /* | |
87 | * sys_iopl has to be used when you want to access the IO ports | |
88 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped | |
89 | * you'd need 8kB of bitmaps/process, which is a bit excessive. | |
90 | * | |
65ea5b03 | 91 | * Here we just change the flags value on the stack: we allow |
1da177e4 LT |
92 | * only the super-user to do it. This depends on the stack-layout |
93 | * on system-call entry - see also fork() and the signal handling | |
94 | * code. | |
95 | */ | |
27f59559 | 96 | long sys_iopl(unsigned int level, struct pt_regs *regs) |
1da177e4 | 97 | { |
65ea5b03 | 98 | unsigned int old = (regs->flags >> 12) & 3; |
27f59559 | 99 | struct thread_struct *t = ¤t->thread; |
1da177e4 LT |
100 | |
101 | if (level > 3) | |
102 | return -EINVAL; | |
103 | /* Trying to gain more privileges? */ | |
104 | if (level > old) { | |
105 | if (!capable(CAP_SYS_RAWIO)) | |
106 | return -EPERM; | |
107 | } | |
ccafa59a | 108 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); |
a1bf250a CW |
109 | t->iopl = level << 12; |
110 | set_iopl_mask(t->iopl); | |
27f59559 BG |
111 | |
112 | return 0; | |
113 | } |