Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 215 insertions, 0 deletions

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
new file mode 100644
index 0000000000..e2fab3ceb0
--- /dev/null
+++ b/arch/x86/kernel/ioport.c
@@ -0,0 +1,215 @@
+// 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/capability.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/bitmap.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <asm/io_bitmap.h>
+#include <asm/desc.h>
+#include <asm/syscalls.h>
+
+#ifdef CONFIG_X86_IOPL_IOPERM
+
+static atomic64_t io_bitmap_sequence;
+
+void io_bitmap_share(struct task_struct *tsk)
+{
+	/* Can be NULL when current->thread.iopl_emul == 3 */
+	if (current->thread.io_bitmap) {
+		/*
+		 * Take a refcount on current's bitmap. It can be used by
+		 * both tasks as long as none of them changes the bitmap.
+		 */
+		refcount_inc(&current->thread.io_bitmap->refcnt);
+		tsk->thread.io_bitmap = current->thread.io_bitmap;
+	}
+	set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+}
+
+static void task_update_io_bitmap(struct task_struct *tsk)
+{
+	struct thread_struct *t = &tsk->thread;
+
+	if (t->iopl_emul == 3 || t->io_bitmap) {
+		/* TSS update is handled on exit to user space */
+		set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+	} else {
+		clear_tsk_thread_flag(tsk, TIF_IO_BITMAP);
+		/* Invalidate TSS */
+		preempt_disable();
+		tss_update_io_bitmap();
+		preempt_enable();
+	}
+}
+
+void io_bitmap_exit(struct task_struct *tsk)
+{
+	struct io_bitmap *iobm = tsk->thread.io_bitmap;
+
+	tsk->thread.io_bitmap = NULL;
+	task_update_io_bitmap(tsk);
+	if (iobm && refcount_dec_and_test(&iobm->refcnt))
+		kfree(iobm);
+}
+
+/*
+ * 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;
+	unsigned int i, max_long;
+	struct io_bitmap *iobm;
+
+	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
+		return -EINVAL;
+	if (turn_on && (!capable(CAP_SYS_RAWIO) ||
+			security_locked_down(LOCKDOWN_IOPORT)))
+		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:
+	 */
+	iobm = t->io_bitmap;
+	if (!iobm) {
+		/* No point to allocate a bitmap just to clear permissions */
+		if (!turn_on)
+			return 0;
+		iobm = kmalloc(sizeof(*iobm), GFP_KERNEL);
+		if (!iobm)
+			return -ENOMEM;
+
+		memset(iobm->bitmap, 0xff, sizeof(iobm->bitmap));
+		refcount_set(&iobm->refcnt, 1);
+	}
+
+	/*
+	 * If the bitmap is not shared, then nothing can take a refcount as
+	 * current can obviously not fork at the same time. If it's shared
+	 * duplicate it and drop the refcount on the original one.
+	 */
+	if (refcount_read(&iobm->refcnt) > 1) {
+		iobm = kmemdup(iobm, sizeof(*iobm), GFP_KERNEL);
+		if (!iobm)
+			return -ENOMEM;
+		refcount_set(&iobm->refcnt, 1);
+		io_bitmap_exit(current);
+	}
+
+	/*
+	 * Store the bitmap pointer (might be the same if the task already
+	 * head one). Must be done here so freeing the bitmap when all
+	 * permissions are dropped has the pointer set up.
+	 */
+	t->io_bitmap = iobm;
+	/* Mark it active for context switching and exit to user mode */
+	set_thread_flag(TIF_IO_BITMAP);
+
+	/*
+	 * Update the tasks bitmap. The update of the TSS bitmap happens on
+	 * exit to user mode. So this needs no protection.
+	 */
+	if (turn_on)
+		bitmap_clear(iobm->bitmap, from, num);
+	else
+		bitmap_set(iobm->bitmap, from, num);
+
+	/*
+	 * Search for a (possibly new) maximum. This is simple and stupid,
+	 * to keep it obviously correct:
+	 */
+	max_long = UINT_MAX;
+	for (i = 0; i < IO_BITMAP_LONGS; i++) {
+		if (iobm->bitmap[i] != ~0UL)
+			max_long = i;
+	}
+	/* All permissions dropped? */
+	if (max_long == UINT_MAX) {
+		io_bitmap_exit(current);
+		return 0;
+	}
+
+	iobm->max = (max_long + 1) * sizeof(unsigned long);
+
+	/*
+	 * Update the sequence number to force a TSS update on return to
+	 * user mode.
+	 */
+	iobm->sequence = atomic64_add_return(1, &io_bitmap_sequence);
+
+	return 0;
+}
+
+SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
+{
+	return ksys_ioperm(from, num, turn_on);
+}
+
+/*
+ * The sys_iopl functionality depends on the level argument, which if
+ * granted for the task is used to enable access to all 65536 I/O ports.
+ *
+ * This does not use the IOPL mechanism provided by the CPU as that would
+ * also allow the user space task to use the CLI/STI instructions.
+ *
+ * Disabling interrupts in a user space task is dangerous as it might lock
+ * up the machine and the semantics vs. syscalls and exceptions is
+ * undefined.
+ *
+ * Setting IOPL to level 0-2 is disabling I/O permissions. Level 3
+ * 3 enables them.
+ *
+ * IOPL is strictly per thread and inherited on fork.
+ */
+SYSCALL_DEFINE1(iopl, unsigned int, level)
+{
+	struct thread_struct *t = &current->thread;
+	unsigned int old;
+
+	if (level > 3)
+		return -EINVAL;
+
+	old = t->iopl_emul;
+
+	/* No point in going further if nothing changes */
+	if (level == old)
+		return 0;
+
+	/* Trying to gain more privileges? */
+	if (level > old) {
+		if (!capable(CAP_SYS_RAWIO) ||
+		    security_locked_down(LOCKDOWN_IOPORT))
+			return -EPERM;
+	}
+
+	t->iopl_emul = level;
+	task_update_io_bitmap(current);
+
+	return 0;
+}
+
+#else /* CONFIG_X86_IOPL_IOPERM */
+
+long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
+{
+	return -ENOSYS;
+}
+SYSCALL_DEFINE3(ioperm, unsigned long, from, unsigned long, num, int, turn_on)
+{
+	return -ENOSYS;
+}
+
+SYSCALL_DEFINE1(iopl, unsigned int, level)
+{
+	return -ENOSYS;
+}
+#endif