1 files changed, 154 insertions, 0 deletions

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
new file mode 100644
index 000000000000..50e5e4a31c85
--- /dev/null
+++ b/arch/x86/kernel/ioport.c
@@ -0,0 +1,154 @@
+/*
+ * This contains the io-permission bitmap code - written by obz, with changes
+ * by Linus. 32/64 bits code unification by Miguel Botón.
+ */
+
+#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/stddef.h>
+#include <linux/slab.h>
+#include <linux/thread_info.h>
+#include <linux/syscalls.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 int i;
+
+	for (i = base; i < base + extent; i++) {
+		if (new_value)
+			__set_bit(i, bitmap);
+		else
+			__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)
+{
+	struct thread_struct * t = &current->thread;
+	struct tss_struct * tss;
+	unsigned int i, max_long, bytes, bytes_updated;
+
+	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) {
+		unsigned long *bitmap = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
+
+		if (!bitmap)
+			return -ENOMEM;
+
+		memset(bitmap, 0xff, IO_BITMAP_BYTES);
+		t->io_bitmap_ptr = bitmap;
+		set_thread_flag(TIF_IO_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(unsigned long);
+	bytes_updated = max(bytes, t->io_bitmap_max);
+
+	t->io_bitmap_max = bytes;
+
+#ifdef CONFIG_X86_32
+	/*
+	 * 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->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+	tss->io_bitmap_owner = NULL;
+#else
+	/* Update the TSS: */
+	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
+#endif
+
+	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 flags 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.
+ */
+static int do_iopl(unsigned int level, struct pt_regs *regs)
+{
+	unsigned int old = (regs->flags >> 12) & 3;
+
+	if (level > 3)
+		return -EINVAL;
+	/* Trying to gain more privileges? */
+	if (level > old) {
+		if (!capable(CAP_SYS_RAWIO))
+			return -EPERM;
+	}
+	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
+
+	return 0;
+}
+
+#ifdef CONFIG_X86_32
+asmlinkage long sys_iopl(unsigned long regsp)
+{
+	struct pt_regs *regs = (struct pt_regs *)&regsp;
+	unsigned int level = regs->bx;
+	struct thread_struct *t = &current->thread;
+	int rc;
+
+	rc = do_iopl(level, regs);
+	if (rc < 0)
+		goto out;
+
+	t->iopl = level << 12;
+	set_iopl_mask(t->iopl);
+out:
+	return rc;
+}
+#else
+asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
+{
+	return do_iopl(level, regs);
+}
+#endif