Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 138 insertions, 0 deletions

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
new file mode 100644
index 000000000..0fe1c8782
--- /dev/null
+++ b/arch/x86/kernel/ioport.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/sched/task_stack.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>
+#include <linux/bitmap.h>
+#include <asm/syscalls.h>
+#include <asm/desc.h>
+
+/*
+ * this changes the io permissions bitmap in the current task.
+ */
+long ksys_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);
+
+		/*
+		 * Now that we have an IO bitmap, we need our TSS limit to be
+		 * correct.  It's fine if we are preempted after doing this:
+		 * with TIF_IO_BITMAP set, context switches will keep our TSS
+		 * limit correct.
+		 */
+		preempt_disable();
+		refresh_tss_limit();
+		preempt_enable();
+	}
+
+	/*
+	 * 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(cpu_tss_rw, get_cpu());
+
+	if (turn_on)
+		bitmap_clear(t->io_bitmap_ptr, from, num);
+	else
+		bitmap_set(t->io_bitmap_ptr, from, num);
+
+	/*
+	 * 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;
+
+	/* Update the TSS: */
+	memcpy(tss->io_bitmap, t->io_bitmap_ptr, bytes_updated);
+
+	put_cpu();
+
+	return 0;
+}
+
+SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
+{
+	return ksys_ioperm(from, num, turn_on);
+}
+
+/*
+ * 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.
+ */
+SYSCALL_DEFINE1(iopl, unsigned int, level)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct thread_struct *t = &current->thread;
+
+	/*
+	 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
+	 * and changing them has no effect.
+	 */
+	unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
+
+	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 << X86_EFLAGS_IOPL_BIT);
+	t->iopl = level << X86_EFLAGS_IOPL_BIT;
+	set_iopl_mask(t->iopl);
+
+	return 0;
+}