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> |
bbc1f698 | 17 | #include <asm/syscalls.h> |
1da177e4 LT |
18 | |
19 | /* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */ | |
f2f58178 TG |
20 | static void set_bitmap(unsigned long *bitmap, unsigned int base, |
21 | unsigned int extent, int new_value) | |
1da177e4 | 22 | { |
f2f58178 | 23 | unsigned int i; |
1da177e4 | 24 | |
f2f58178 | 25 | for (i = base; i < base + extent; i++) { |
1da177e4 | 26 | if (new_value) |
f2f58178 | 27 | __set_bit(i, bitmap); |
1da177e4 | 28 | else |
f2f58178 | 29 | __clear_bit(i, bitmap); |
1da177e4 LT |
30 | } |
31 | } | |
32 | ||
1da177e4 LT |
33 | /* |
34 | * this changes the io permissions bitmap in the current task. | |
35 | */ | |
36 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) | |
37 | { | |
5866e1b4 JSR |
38 | struct thread_struct *t = ¤t->thread; |
39 | struct tss_struct *tss; | |
ccafa59a | 40 | unsigned int i, max_long, bytes, bytes_updated; |
1da177e4 LT |
41 | |
42 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) | |
43 | return -EINVAL; | |
44 | if (turn_on && !capable(CAP_SYS_RAWIO)) | |
45 | return -EPERM; | |
46 | ||
47 | /* | |
48 | * If it's the first ioperm() call in this thread's lifetime, set the | |
49 | * IO bitmap up. ioperm() is much less timing critical than clone(), | |
50 | * this is why we delay this operation until now: | |
51 | */ | |
52 | if (!t->io_bitmap_ptr) { | |
9a211abe TG |
53 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
54 | ||
1da177e4 LT |
55 | if (!bitmap) |
56 | return -ENOMEM; | |
57 | ||
58 | memset(bitmap, 0xff, IO_BITMAP_BYTES); | |
59 | t->io_bitmap_ptr = bitmap; | |
b3cf2576 | 60 | set_thread_flag(TIF_IO_BITMAP); |
1da177e4 LT |
61 | } |
62 | ||
63 | /* | |
64 | * do it in the per-thread copy and in the TSS ... | |
65 | * | |
66 | * Disable preemption via get_cpu() - we must not switch away | |
67 | * because the ->io_bitmap_max value must match the bitmap | |
68 | * contents: | |
69 | */ | |
70 | tss = &per_cpu(init_tss, get_cpu()); | |
71 | ||
72 | set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); | |
73 | ||
74 | /* | |
75 | * Search for a (possibly new) maximum. This is simple and stupid, | |
76 | * to keep it obviously correct: | |
77 | */ | |
78 | max_long = 0; | |
79 | for (i = 0; i < IO_BITMAP_LONGS; i++) | |
80 | if (t->io_bitmap_ptr[i] != ~0UL) | |
81 | max_long = i; | |
82 | ||
ccafa59a | 83 | bytes = (max_long + 1) * sizeof(unsigned long); |
84 | bytes_updated = max(bytes, t->io_bitmap_max); | |
1da177e4 | 85 | |
ccafa59a | 86 | t->io_bitmap_max = bytes; |
87 | ||
ccafa59a | 88 | /* Update the TSS: */ |
89 | memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated); | |
1da177e4 LT |
90 | |
91 | put_cpu(); | |
92 | ||
93 | return 0; | |
94 | } | |
95 | ||
96 | /* | |
97 | * sys_iopl has to be used when you want to access the IO ports | |
98 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped | |
99 | * you'd need 8kB of bitmaps/process, which is a bit excessive. | |
100 | * | |
65ea5b03 | 101 | * Here we just change the flags value on the stack: we allow |
1da177e4 LT |
102 | * only the super-user to do it. This depends on the stack-layout |
103 | * on system-call entry - see also fork() and the signal handling | |
104 | * code. | |
105 | */ | |
27f59559 | 106 | long sys_iopl(unsigned int level, struct pt_regs *regs) |
1da177e4 | 107 | { |
65ea5b03 | 108 | unsigned int old = (regs->flags >> 12) & 3; |
27f59559 | 109 | struct thread_struct *t = ¤t->thread; |
1da177e4 LT |
110 | |
111 | if (level > 3) | |
112 | return -EINVAL; | |
113 | /* Trying to gain more privileges? */ | |
114 | if (level > old) { | |
115 | if (!capable(CAP_SYS_RAWIO)) | |
116 | return -EPERM; | |
117 | } | |
ccafa59a | 118 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12); |
a1bf250a CW |
119 | t->iopl = level << 12; |
120 | set_iopl_mask(t->iopl); | |
27f59559 BG |
121 | |
122 | return 0; | |
123 | } |