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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * This contains the io-permission bitmap code - written by obz, with changes
mboton@gmail.comccafa592008-01-30 13:33:10 +01003 * by Linus. 32/64 bits code unification by Miguel Botón.
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 */
5
6#include <linux/sched.h>
7#include <linux/kernel.h>
Randy Dunlapa9415642006-01-11 12:17:48 -08008#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/errno.h>
10#include <linux/types.h>
11#include <linux/ioport.h>
12#include <linux/smp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/stddef.h>
14#include <linux/slab.h>
15#include <linux/thread_info.h>
Adrian Bunkca906e42007-05-02 19:27:10 +020016#include <linux/syscalls.h>
Jaswinder Singhbbc1f692008-07-21 21:34:13 +053017#include <asm/syscalls.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018
19/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
Thomas Gleixnerf2f58172008-01-30 13:30:23 +010020static void set_bitmap(unsigned long *bitmap, unsigned int base,
21 unsigned int extent, int new_value)
Linus Torvalds1da177e2005-04-16 15:20:36 -070022{
Thomas Gleixnerf2f58172008-01-30 13:30:23 +010023 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Thomas Gleixnerf2f58172008-01-30 13:30:23 +010025 for (i = base; i < base + extent; i++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070026 if (new_value)
Thomas Gleixnerf2f58172008-01-30 13:30:23 +010027 __set_bit(i, bitmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -070028 else
Thomas Gleixnerf2f58172008-01-30 13:30:23 +010029 __clear_bit(i, bitmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 }
31}
32
Linus Torvalds1da177e2005-04-16 15:20:36 -070033/*
34 * this changes the io permissions bitmap in the current task.
35 */
36asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
37{
Jaswinder Singh Rajput5866e1b2009-01-04 16:29:32 +053038 struct thread_struct *t = &current->thread;
39 struct tss_struct *tss;
mboton@gmail.comccafa592008-01-30 13:33:10 +010040 unsigned int i, max_long, bytes, bytes_updated;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
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) {
Thomas Gleixner9a211ab2008-01-30 13:30:24 +010053 unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
54
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 if (!bitmap)
56 return -ENOMEM;
57
58 memset(bitmap, 0xff, IO_BITMAP_BYTES);
59 t->io_bitmap_ptr = bitmap;
Stephane Eranianb3cf2572006-07-09 21:12:39 -040060 set_thread_flag(TIF_IO_BITMAP);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 }
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
mboton@gmail.comccafa592008-01-30 13:33:10 +010083 bytes = (max_long + 1) * sizeof(unsigned long);
84 bytes_updated = max(bytes, t->io_bitmap_max);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
mboton@gmail.comccafa592008-01-30 13:33:10 +010086 t->io_bitmap_max = bytes;
87
mboton@gmail.comccafa592008-01-30 13:33:10 +010088 /* Update the TSS: */
89 memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
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 *
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100101 * Here we just change the flags value on the stack: we allow
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 * 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 */
Brian Gerst27f59552009-12-09 19:01:52 -0500106long sys_iopl(unsigned int level, struct pt_regs *regs)
Chris Wrighta1bf2502008-01-30 13:33:10 +0100107{
108 unsigned int old = (regs->flags >> 12) & 3;
Brian Gerst27f59552009-12-09 19:01:52 -0500109 struct thread_struct *t = &current->thread;
Chris Wrighta1bf2502008-01-30 13:33:10 +0100110
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 }
118 regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
Brian Gerst27f59552009-12-09 19:01:52 -0500119 t->iopl = level << 12;
120 set_iopl_mask(t->iopl);
Chris Wrighta1bf2502008-01-30 13:33:10 +0100121
122 return 0;
123}