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. */ | |
f2f58178 TG |
19 | static void set_bitmap(unsigned long *bitmap, unsigned int base, |
20 | unsigned int extent, int new_value) | |
1da177e4 | 21 | { |
f2f58178 | 22 | unsigned int i; |
1da177e4 | 23 | |
f2f58178 | 24 | for (i = base; i < base + extent; i++) { |
1da177e4 | 25 | if (new_value) |
f2f58178 | 26 | __set_bit(i, bitmap); |
1da177e4 | 27 | else |
f2f58178 | 28 | __clear_bit(i, bitmap); |
1da177e4 LT |
29 | } |
30 | } | |
31 | ||
1da177e4 LT |
32 | /* |
33 | * this changes the io permissions bitmap in the current task. | |
34 | */ | |
35 | asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on) | |
36 | { | |
1da177e4 LT |
37 | struct thread_struct * t = ¤t->thread; |
38 | struct tss_struct * tss; | |
9a211abe | 39 | unsigned long i, max_long; |
1da177e4 LT |
40 | |
41 | if ((from + num <= from) || (from + num > IO_BITMAP_BITS)) | |
42 | return -EINVAL; | |
43 | if (turn_on && !capable(CAP_SYS_RAWIO)) | |
44 | return -EPERM; | |
45 | ||
46 | /* | |
47 | * If it's the first ioperm() call in this thread's lifetime, set the | |
48 | * IO bitmap up. ioperm() is much less timing critical than clone(), | |
49 | * this is why we delay this operation until now: | |
50 | */ | |
51 | if (!t->io_bitmap_ptr) { | |
9a211abe TG |
52 | unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
53 | ||
1da177e4 LT |
54 | if (!bitmap) |
55 | return -ENOMEM; | |
56 | ||
57 | memset(bitmap, 0xff, IO_BITMAP_BYTES); | |
58 | t->io_bitmap_ptr = bitmap; | |
b3cf2576 | 59 | set_thread_flag(TIF_IO_BITMAP); |
1da177e4 LT |
60 | } |
61 | ||
62 | /* | |
63 | * do it in the per-thread copy and in the TSS ... | |
64 | * | |
65 | * Disable preemption via get_cpu() - we must not switch away | |
66 | * because the ->io_bitmap_max value must match the bitmap | |
67 | * contents: | |
68 | */ | |
69 | tss = &per_cpu(init_tss, get_cpu()); | |
70 | ||
71 | set_bitmap(t->io_bitmap_ptr, from, num, !turn_on); | |
72 | ||
73 | /* | |
74 | * Search for a (possibly new) maximum. This is simple and stupid, | |
75 | * to keep it obviously correct: | |
76 | */ | |
77 | max_long = 0; | |
78 | for (i = 0; i < IO_BITMAP_LONGS; i++) | |
79 | if (t->io_bitmap_ptr[i] != ~0UL) | |
80 | max_long = i; | |
81 | ||
9a211abe | 82 | t->io_bitmap_max = (max_long + 1) * sizeof(unsigned long); |
1da177e4 LT |
83 | |
84 | /* | |
85 | * Sets the lazy trigger so that the next I/O operation will | |
86 | * reload the correct bitmap. | |
f912696a BO |
87 | * Reset the owner so that a process switch will not set |
88 | * tss->io_bitmap_base to IO_BITMAP_OFFSET. | |
1da177e4 | 89 | */ |
a75c54f9 | 90 | tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; |
f912696a | 91 | tss->io_bitmap_owner = NULL; |
1da177e4 LT |
92 | |
93 | put_cpu(); | |
94 | ||
95 | return 0; | |
96 | } | |
97 | ||
98 | /* | |
99 | * sys_iopl has to be used when you want to access the IO ports | |
100 | * beyond the 0x3ff range: to get the full 65536 ports bitmapped | |
101 | * you'd need 8kB of bitmaps/process, which is a bit excessive. | |
102 | * | |
65ea5b03 | 103 | * Here we just change the flags value on the stack: we allow |
1da177e4 LT |
104 | * only the super-user to do it. This depends on the stack-layout |
105 | * on system-call entry - see also fork() and the signal handling | |
106 | * code. | |
107 | */ | |
108 | ||
9a211abe | 109 | asmlinkage long sys_iopl(unsigned long regsp) |
1da177e4 | 110 | { |
9a211abe | 111 | volatile struct pt_regs *regs = (struct pt_regs *)®sp; |
65ea5b03 PA |
112 | unsigned int level = regs->bx; |
113 | unsigned int old = (regs->flags >> 12) & 3; | |
a5201129 | 114 | struct thread_struct *t = ¤t->thread; |
1da177e4 LT |
115 | |
116 | if (level > 3) | |
117 | return -EINVAL; | |
118 | /* Trying to gain more privileges? */ | |
119 | if (level > old) { | |
120 | if (!capable(CAP_SYS_RAWIO)) | |
121 | return -EPERM; | |
122 | } | |
9a211abe | 123 | |
a5201129 | 124 | t->iopl = level << 12; |
65ea5b03 | 125 | regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | t->iopl; |
a5201129 | 126 | set_iopl_mask(t->iopl); |
9a211abe | 127 | |
1da177e4 LT |
128 | return 0; |
129 | } |