PageRenderTime 25ms CodeModel.GetById 14ms app.highlight 8ms RepoModel.GetById 2ms app.codeStats 0ms

/arch/x86_64/kernel/ioport.c

https://bitbucket.org/evzijst/gittest
C | 117 lines | 62 code | 17 blank | 38 comment | 15 complexity | a09a9b617b36923d3b3c6f77eb44acce MD5 | raw file
  1/*
  2 *	linux/arch/x86_64/kernel/ioport.c
  3 *
  4 * This contains the io-permission bitmap code - written by obz, with changes
  5 * by Linus.
  6 */
  7
  8#include <linux/sched.h>
  9#include <linux/kernel.h>
 10#include <linux/errno.h>
 11#include <linux/types.h>
 12#include <linux/ioport.h>
 13#include <linux/smp.h>
 14#include <linux/smp_lock.h>
 15#include <linux/stddef.h>
 16#include <linux/slab.h>
 17#include <linux/thread_info.h>
 18
 19/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
 20static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)
 21{
 22	int i;
 23		if (new_value)
 24		for (i = base; i < base + extent; i++) 
 25			__set_bit(i, bitmap); 
 26		else
 27		for (i = base; i < base + extent; i++) 
 28			clear_bit(i, bitmap); 
 29}
 30
 31/*
 32 * this changes the io permissions bitmap in the current task.
 33 */
 34asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 35{
 36	unsigned int i, max_long, bytes, bytes_updated;
 37	struct thread_struct * t = &current->thread;
 38	struct tss_struct * tss;
 39	unsigned long *bitmap;
 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) {
 52		bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 53		if (!bitmap)
 54			return -ENOMEM;
 55
 56		memset(bitmap, 0xff, IO_BITMAP_BYTES);
 57		t->io_bitmap_ptr = bitmap;
 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 *
 98 * Here we just change the eflags value on the stack: we allow
 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
104asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
105{
106	unsigned int old = (regs->eflags >> 12) & 3;
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	}
115	regs->eflags = (regs->eflags &~ 0x3000UL) | (level << 12);
116	return 0;
117}