[linux-2.6-block.git] / arch / x86_64 / kernel / ioport.c

/*
 *	linux/arch/x86_64/kernel/ioport.c
 *
 * This contains the io-permission bitmap code - written by obz, with changes
 * by Linus.
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/ioport.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/thread_info.h>

/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)
{
	int i;
		if (new_value)
		for (i = base; i < base + extent; i++) 
			__set_bit(i, bitmap); 
		else
		for (i = base; i < base + extent; i++) 
			clear_bit(i, bitmap); 
}

/*
 * this changes the io permissions bitmap in the current task.
 */
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
	unsigned int i, max_long, bytes, bytes_updated;
	struct thread_struct * t = &current->thread;
	struct tss_struct * tss;
	unsigned long *bitmap;

	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
		return -EINVAL;
	if (turn_on && !capable(CAP_SYS_RAWIO))
		return -EPERM;

	/*
	 * If it's the first ioperm() call in this thread's lifetime, set the
	 * IO bitmap up. ioperm() is much less timing critical than clone(),
	 * this is why we delay this operation until now:
	 */
	if (!t->io_bitmap_ptr) {
		bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
		if (!bitmap)
			return -ENOMEM;

		memset(bitmap, 0xff, IO_BITMAP_BYTES);
		t->io_bitmap_ptr = bitmap;
	}

	/*
	 * do it in the per-thread copy and in the TSS ...
	 *
	 * Disable preemption via get_cpu() - we must not switch away
	 * because the ->io_bitmap_max value must match the bitmap
	 * contents:
	 */
	tss = &per_cpu(init_tss, get_cpu());

	set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);

	/*
	 * Search for a (possibly new) maximum. This is simple and stupid,
	 * to keep it obviously correct:
	 */
	max_long = 0;
	for (i = 0; i < IO_BITMAP_LONGS; i++)
		if (t->io_bitmap_ptr[i] != ~0UL)
			max_long = i;

	bytes = (max_long + 1) * sizeof(long);
	bytes_updated = max(bytes, t->io_bitmap_max);

	t->io_bitmap_max = bytes;

	/* Update the TSS: */
	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);

	put_cpu();

	return 0;
}

/*
 * sys_iopl has to be used when you want to access the IO ports
 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
 * you'd need 8kB of bitmaps/process, which is a bit excessive.
 *
 * Here we just change the eflags value on the stack: we allow
 * only the super-user to do it. This depends on the stack-layout
 * on system-call entry - see also fork() and the signal handling
 * code.
 */

asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
{
	unsigned int old = (regs->eflags >> 12) & 3;

	if (level > 3)
		return -EINVAL;
	/* Trying to gain more privileges? */
	if (level > old) {
		if (!capable(CAP_SYS_RAWIO))
			return -EPERM;
	}
	regs->eflags = (regs->eflags &~ 0x3000UL) | (level << 12);
	return 0;
}
Commit	Line	Data
1da177e4 LT	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>
a9415644	10	#include <linux/capability.h>
1da177e4 LT	11	#include <linux/errno.h>
	12	#include <linux/types.h>
	13	#include <linux/ioport.h>
	14	#include <linux/smp.h>
	15	#include <linux/smp_lock.h>
	16	#include <linux/stddef.h>
	17	#include <linux/slab.h>
	18	#include <linux/thread_info.h>
	19
	20	/* Set EXTENT bits starting at BASE in BITMAP to value TURN_ON. */
	21	static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int extent, int new_value)
	22	{
	23	int i;
	24	if (new_value)
	25	for (i = base; i < base + extent; i++)
	26	__set_bit(i, bitmap);
	27	else
	28	for (i = base; i < base + extent; i++)
	29	clear_bit(i, bitmap);
	30	}
	31
	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	{
	37	unsigned int i, max_long, bytes, bytes_updated;
	38	struct thread_struct * t = &current->thread;
	39	struct tss_struct * tss;
	40	unsigned long *bitmap;
	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) {
	53	bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
	54	if (!bitmap)
	55	return -ENOMEM;
	56
	57	memset(bitmap, 0xff, IO_BITMAP_BYTES);
	58	t->io_bitmap_ptr = bitmap;
	59	}
	60
	61	/*
	62	* do it in the per-thread copy and in the TSS ...
	63	*
	64	* Disable preemption via get_cpu() - we must not switch away
	65	* because the ->io_bitmap_max value must match the bitmap
	66	* contents:
	67	*/
	68	tss = &per_cpu(init_tss, get_cpu());
	69
	70	set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
	71
	72	/*
	73	* Search for a (possibly new) maximum. This is simple and stupid,
	74	* to keep it obviously correct:
75	*/
76	max_long = 0;
77	for (i = 0; i < IO_BITMAP_LONGS; i++)
78	if (t->io_bitmap_ptr[i] != ~0UL)
79	max_long = i;
80
81	bytes = (max_long + 1) * sizeof(long);
82	bytes_updated = max(bytes, t->io_bitmap_max);
83
84	t->io_bitmap_max = bytes;
85
86	/* Update the TSS: */
87	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
88
89	put_cpu();
90
91	return 0;
92	}
93
94	/*
95	* sys_iopl has to be used when you want to access the IO ports
96	* beyond the 0x3ff range: to get the full 65536 ports bitmapped
97	* you'd need 8kB of bitmaps/process, which is a bit excessive.
98	*
99	* Here we just change the eflags value on the stack: we allow
100	* only the super-user to do it. This depends on the stack-layout
101	* on system-call entry - see also fork() and the signal handling
102	* code.
103	*/
104
105	asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
106	{
107	unsigned int old = (regs->eflags >> 12) & 3;
108
109	if (level > 3)
110	return -EINVAL;
111	/* Trying to gain more privileges? */
112	if (level > old) {
113	if (!capable(CAP_SYS_RAWIO))
114	return -EPERM;
115	}
116	regs->eflags = (regs->eflags &~ 0x3000UL) \| (level << 12);
117	return 0;
118	}