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-rw-r--r--arch/i386/kernel/ioport.c147
1 files changed, 147 insertions, 0 deletions
diff --git a/arch/i386/kernel/ioport.c b/arch/i386/kernel/ioport.c
new file mode 100644
index 000000000000..8b25160393c1
--- /dev/null
+++ b/arch/i386/kernel/ioport.c
@@ -0,0 +1,147 @@
+/*
+ * 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/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.
+ */
+ tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+
+ 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;
+
+ 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);
+ /* Make sure we return the long way (not sysenter) */
+ set_thread_flag(TIF_IRET);
+ return 0;
+}