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