1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * This contains the io-permission bitmap code - written by obz, with changes
  4 * by Linus. 32/64 bits code unification by Miguel Botón.
  5 */
  6
  7#include <linux/sched.h>
  8#include <linux/sched/task_stack.h>
  9#include <linux/kernel.h>
 10#include <linux/capability.h>
 11#include <linux/errno.h>
 12#include <linux/types.h>
 13#include <linux/ioport.h>
 14#include <linux/smp.h>
 15#include <linux/stddef.h>
 16#include <linux/slab.h>
 17#include <linux/thread_info.h>
 18#include <linux/syscalls.h>
 19#include <linux/bitmap.h>
 20#include <asm/syscalls.h>
 21#include <asm/desc.h>
 22
 23/*
 24 * this changes the io permissions bitmap in the current task.
 25 */
 26long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
 27{
 28	struct thread_struct *t = &current->thread;
 29	struct tss_struct *tss;
 30	unsigned int i, max_long, bytes, bytes_updated;
 31
 32	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
 33		return -EINVAL;
 34	if (turn_on && !capable(CAP_SYS_RAWIO))
 35		return -EPERM;
 36
 37	/*
 38	 * If it's the first ioperm() call in this thread's lifetime, set the
 39	 * IO bitmap up. ioperm() is much less timing critical than clone(),
 40	 * this is why we delay this operation until now:
 41	 */
 42	if (!t->io_bitmap_ptr) {
 43		unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 44
 45		if (!bitmap)
 46			return -ENOMEM;
 47
 48		memset(bitmap, 0xff, IO_BITMAP_BYTES);
 49		t->io_bitmap_ptr = bitmap;
 50		set_thread_flag(TIF_IO_BITMAP);
 51
 52		/*
 53		 * Now that we have an IO bitmap, we need our TSS limit to be
 54		 * correct.  It's fine if we are preempted after doing this:
 55		 * with TIF_IO_BITMAP set, context switches will keep our TSS
 56		 * limit correct.
 57		 */
 58		preempt_disable();
 59		refresh_tss_limit();
 60		preempt_enable();
 61	}
 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(cpu_tss_rw, get_cpu());
 71
 72	if (turn_on)
 73		bitmap_clear(t->io_bitmap_ptr, from, num);
 74	else
 75		bitmap_set(t->io_bitmap_ptr, from, num);
 76
 77	/*
 78	 * Search for a (possibly new) maximum. This is simple and stupid,
 79	 * to keep it obviously correct:
 80	 */
 81	max_long = 0;
 82	for (i = 0; i < IO_BITMAP_LONGS; i++)
 83		if (t->io_bitmap_ptr[i] != ~0UL)
 84			max_long = i;
 85
 86	bytes = (max_long + 1) * sizeof(unsigned long);
 87	bytes_updated = max(bytes, t->io_bitmap_max);
 88
 89	t->io_bitmap_max = bytes;
 90
 91	/* Update the TSS: */
 92	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
 93
 94	put_cpu();
 95
 96	return 0;
 97}
 98
 99SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
100{
101	return ksys_ioperm(from, num, turn_on);
102}
103
104/*
105 * sys_iopl has to be used when you want to access the IO ports
106 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
107 * you'd need 8kB of bitmaps/process, which is a bit excessive.
108 *
109 * Here we just change the flags value on the stack: we allow
110 * only the super-user to do it. This depends on the stack-layout
111 * on system-call entry - see also fork() and the signal handling
112 * code.
113 */
114SYSCALL_DEFINE1(iopl, unsigned int, level)
115{
116	struct pt_regs *regs = current_pt_regs();
117	struct thread_struct *t = &current->thread;
118
119	/*
120	 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
121	 * and changing them has no effect.
122	 */
123	unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
124
125	if (level > 3)
126		return -EINVAL;
127	/* Trying to gain more privileges? */
128	if (level > old) {
129		if (!capable(CAP_SYS_RAWIO))
130			return -EPERM;
131	}
132	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
133		(level << X86_EFLAGS_IOPL_BIT);
134	t->iopl = level << X86_EFLAGS_IOPL_BIT;
135	set_iopl_mask(t->iopl);
136
137	return 0;
138}

 
  1/*
  2 * This contains the io-permission bitmap code - written by obz, with changes
  3 * by Linus. 32/64 bits code unification by Miguel Botón.
  4 */
  5
  6#include <linux/sched.h>
 
  7#include <linux/kernel.h>
  8#include <linux/capability.h>
  9#include <linux/errno.h>
 10#include <linux/types.h>
 11#include <linux/ioport.h>
 12#include <linux/smp.h>
 13#include <linux/stddef.h>
 14#include <linux/slab.h>
 15#include <linux/thread_info.h>
 16#include <linux/syscalls.h>
 17#include <linux/bitmap.h>
 18#include <asm/syscalls.h>
 
 19
 20/*
 21 * this changes the io permissions bitmap in the current task.
 22 */
 23asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 24{
 25	struct thread_struct *t = &current->thread;
 26	struct tss_struct *tss;
 27	unsigned int i, max_long, bytes, bytes_updated;
 28
 29	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
 30		return -EINVAL;
 31	if (turn_on && !capable(CAP_SYS_RAWIO))
 32		return -EPERM;
 33
 34	/*
 35	 * If it's the first ioperm() call in this thread's lifetime, set the
 36	 * IO bitmap up. ioperm() is much less timing critical than clone(),
 37	 * this is why we delay this operation until now:
 38	 */
 39	if (!t->io_bitmap_ptr) {
 40		unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 41
 42		if (!bitmap)
 43			return -ENOMEM;
 44
 45		memset(bitmap, 0xff, IO_BITMAP_BYTES);
 46		t->io_bitmap_ptr = bitmap;
 47		set_thread_flag(TIF_IO_BITMAP);
 
 
 
 
 
 
 
 
 
 
 48	}
 49
 50	/*
 51	 * do it in the per-thread copy and in the TSS ...
 52	 *
 53	 * Disable preemption via get_cpu() - we must not switch away
 54	 * because the ->io_bitmap_max value must match the bitmap
 55	 * contents:
 56	 */
 57	tss = &per_cpu(init_tss, get_cpu());
 58
 59	if (turn_on)
 60		bitmap_clear(t->io_bitmap_ptr, from, num);
 61	else
 62		bitmap_set(t->io_bitmap_ptr, from, num);
 63
 64	/*
 65	 * Search for a (possibly new) maximum. This is simple and stupid,
 66	 * to keep it obviously correct:
 67	 */
 68	max_long = 0;
 69	for (i = 0; i < IO_BITMAP_LONGS; i++)
 70		if (t->io_bitmap_ptr[i] != ~0UL)
 71			max_long = i;
 72
 73	bytes = (max_long + 1) * sizeof(unsigned long);
 74	bytes_updated = max(bytes, t->io_bitmap_max);
 75
 76	t->io_bitmap_max = bytes;
 77
 78	/* Update the TSS: */
 79	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
 80
 81	put_cpu();
 82
 83	return 0;
 84}
 85
 
 
 
 
 
 86/*
 87 * sys_iopl has to be used when you want to access the IO ports
 88 * beyond the 0x3ff range: to get the full 65536 ports bitmapped
 89 * you'd need 8kB of bitmaps/process, which is a bit excessive.
 90 *
 91 * Here we just change the flags value on the stack: we allow
 92 * only the super-user to do it. This depends on the stack-layout
 93 * on system-call entry - see also fork() and the signal handling
 94 * code.
 95 */
 96long sys_iopl(unsigned int level, struct pt_regs *regs)
 97{
 98	unsigned int old = (regs->flags >> 12) & 3;
 99	struct thread_struct *t = &current->thread;
100
 
 
 
 
 
 
101	if (level > 3)
102		return -EINVAL;
103	/* Trying to gain more privileges? */
104	if (level > old) {
105		if (!capable(CAP_SYS_RAWIO))
106			return -EPERM;
107	}
108	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
109	t->iopl = level << 12;
 
110	set_iopl_mask(t->iopl);
111
112	return 0;
113}