[deliverable/linux.git] / arch / i386 / kernel / ioport.c

/*
 *	linux/arch/i386/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)
{
	unsigned long mask;
	unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG);
	unsigned int low_index = base & (BITS_PER_LONG-1);
	int length = low_index + extent;

	if (low_index != 0) {
		mask = (~0UL << low_index);
		if (length < BITS_PER_LONG)
			mask &= ~(~0UL << length);
		if (new_value)
			*bitmap_base++ |= mask;
		else
			*bitmap_base++ &= ~mask;
		length -= BITS_PER_LONG;
	}

	mask = (new_value ? ~0UL : 0UL);
	while (length >= BITS_PER_LONG) {
		*bitmap_base++ = mask;
		length -= BITS_PER_LONG;
	}

	if (length > 0) {
		mask = ~(~0UL << length);
		if (new_value)
			*bitmap_base++ |= mask;
		else
			*bitmap_base++ &= ~mask;
	}
}


/*
 * this changes the io permissions bitmap in the current task.
 */
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
{
	unsigned long 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;

	/*
	 * Sets the lazy trigger so that the next I/O operation will
	 * reload the correct bitmap.
	 * Reset the owner so that a process switch will not set
	 * tss->io_bitmap_base to IO_BITMAP_OFFSET.
	 */
	tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
	tss->io_bitmap_owner = NULL;

	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 long unused)
{
	volatile struct pt_regs * regs = (struct pt_regs *) &unused;
	unsigned int level = regs->ebx;
	unsigned int old = (regs->eflags >> 12) & 3;
	struct thread_struct *t = &current->thread;

	if (level > 3)
		return -EINVAL;
	/* Trying to gain more privileges? */
	if (level > old) {
		if (!capable(CAP_SYS_RAWIO))
			return -EPERM;
	}
	t->iopl = level << 12;
	regs->eflags = (regs->eflags & ~X86_EFLAGS_IOPL) | t->iopl;
	set_iopl_mask(t->iopl);
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/arch/i386/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	unsigned long mask;
	24	unsigned long *bitmap_base = bitmap + (base / BITS_PER_LONG);
	25	unsigned int low_index = base & (BITS_PER_LONG-1);
	26	int length = low_index + extent;
	27
	28	if (low_index != 0) {
	29	mask = (~0UL << low_index);
	30	if (length < BITS_PER_LONG)
	31	mask &= ~(~0UL << length);
	32	if (new_value)
	33	*bitmap_base++ \|= mask;
	34	else
	35	*bitmap_base++ &= ~mask;
	36	length -= BITS_PER_LONG;
	37	}
	38
	39	mask = (new_value ? ~0UL : 0UL);
	40	while (length >= BITS_PER_LONG) {
	41	*bitmap_base++ = mask;
	42	length -= BITS_PER_LONG;
	43	}
	44
	45	if (length > 0) {
	46	mask = ~(~0UL << length);
	47	if (new_value)
	48	*bitmap_base++ \|= mask;
	49	else
	50	*bitmap_base++ &= ~mask;
	51	}
	52	}
	53
	54
	55	/*
	56	* this changes the io permissions bitmap in the current task.
	57	*/
	58	asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
	59	{
	60	unsigned long i, max_long, bytes, bytes_updated;
	61	struct thread_struct * t = &current->thread;
	62	struct tss_struct * tss;
	63	unsigned long *bitmap;
	64
	65	if ((from + num <= from) \|\| (from + num > IO_BITMAP_BITS))
	66	return -EINVAL;
	67	if (turn_on && !capable(CAP_SYS_RAWIO))
	68	return -EPERM;
	69
	70	/*
	71	* If it's the first ioperm() call in this thread's lifetime, set the
	72	* IO bitmap up. ioperm() is much less timing critical than clone(),
	73	* this is why we delay this operation until now:
	74	*/
75	if (!t->io_bitmap_ptr) {
76	bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
77	if (!bitmap)
78	return -ENOMEM;
79
80	memset(bitmap, 0xff, IO_BITMAP_BYTES);
81	t->io_bitmap_ptr = bitmap;
82	}
83
84	/*
85	* do it in the per-thread copy and in the TSS ...
86	*
87	* Disable preemption via get_cpu() - we must not switch away
88	* because the ->io_bitmap_max value must match the bitmap
89	* contents:
90	*/
91	tss = &per_cpu(init_tss, get_cpu());
92
93	set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
94
95	/*
96	* Search for a (possibly new) maximum. This is simple and stupid,
97	* to keep it obviously correct:
98	*/
99	max_long = 0;
100	for (i = 0; i < IO_BITMAP_LONGS; i++)
101	if (t->io_bitmap_ptr[i] != ~0UL)
102	max_long = i;
103
104	bytes = (max_long + 1) * sizeof(long);
105	bytes_updated = max(bytes, t->io_bitmap_max);
106
107	t->io_bitmap_max = bytes;
108
109	/*
110	* Sets the lazy trigger so that the next I/O operation will
111	* reload the correct bitmap.
f912696a BO	112	* Reset the owner so that a process switch will not set
f912696a BO	113	* tss->io_bitmap_base to IO_BITMAP_OFFSET.
1da177e4 LT	114	*/
1da177e4 LT	115	tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
f912696a	116	tss->io_bitmap_owner = NULL;
1da177e4 LT	117
	118	put_cpu();
	119
	120	return 0;
	121	}
	122
	123	/*
	124	* sys_iopl has to be used when you want to access the IO ports
	125	* beyond the 0x3ff range: to get the full 65536 ports bitmapped
	126	* you'd need 8kB of bitmaps/process, which is a bit excessive.
	127	*
	128	* Here we just change the eflags value on the stack: we allow
	129	* only the super-user to do it. This depends on the stack-layout
	130	* on system-call entry - see also fork() and the signal handling
	131	* code.
	132	*/
	133
	134	asmlinkage long sys_iopl(unsigned long unused)
	135	{
	136	volatile struct pt_regs * regs = (struct pt_regs *) &unused;
	137	unsigned int level = regs->ebx;
	138	unsigned int old = (regs->eflags >> 12) & 3;
a5201129	139	struct thread_struct *t = &current->thread;
1da177e4 LT	140
	141	if (level > 3)
	142	return -EINVAL;
	143	/* Trying to gain more privileges? */
	144	if (level > old) {
	145	if (!capable(CAP_SYS_RAWIO))
	146	return -EPERM;
	147	}
a5201129 ZA	148	t->iopl = level << 12;
	149	regs->eflags = (regs->eflags & ~X86_EFLAGS_IOPL) \| t->iopl;
	150	set_iopl_mask(t->iopl);
1da177e4 LT	151	return 0;
1da177e4 LT	152	}