1 files changed, 295 insertions, 0 deletions
diff --git a/kernel/kexec.c b/kernel/kexec.c
new file mode 100644
index 000000000..5ff1dcc4a
--- /dev/null
+++ b/kernel/kexec.c
@@ -0,0 +1,295 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * kexec.c - kexec_load system call
+ * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/capability.h>
+#include <linux/mm.h>
+#include <linux/file.h>
+#include <linux/security.h>
+#include <linux/kexec.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/syscalls.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+
+#include "kexec_internal.h"
+
+static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
+			     unsigned long nr_segments,
+			     struct kexec_segment *segments,
+			     unsigned long flags)
+{
+	int ret;
+	struct kimage *image;
+	bool kexec_on_panic = flags & KEXEC_ON_CRASH;
+
+	if (kexec_on_panic) {
+		/* Verify we have a valid entry point */
+		if ((entry < phys_to_boot_phys(crashk_res.start)) ||
+		    (entry > phys_to_boot_phys(crashk_res.end)))
+			return -EADDRNOTAVAIL;
+	}
+
+	/* Allocate and initialize a controlling structure */
+	image = do_kimage_alloc_init();
+	if (!image)
+		return -ENOMEM;
+
+	image->start = entry;
+	image->nr_segments = nr_segments;
+	memcpy(image->segment, segments, nr_segments * sizeof(*segments));
+
+	if (kexec_on_panic) {
+		/* Enable special crash kernel control page alloc policy. */
+		image->control_page = crashk_res.start;
+		image->type = KEXEC_TYPE_CRASH;
+	}
+
+	ret = sanity_check_segment_list(image);
+	if (ret)
+		goto out_free_image;
+
+	/*
+	 * Find a location for the control code buffer, and add it
+	 * the vector of segments so that it's pages will also be
+	 * counted as destination pages.
+	 */
+	ret = -ENOMEM;
+	image->control_code_page = kimage_alloc_control_pages(image,
+					   get_order(KEXEC_CONTROL_PAGE_SIZE));
+	if (!image->control_code_page) {
+		pr_err("Could not allocate control_code_buffer\n");
+		goto out_free_image;
+	}
+
+	if (!kexec_on_panic) {
+		image->swap_page = kimage_alloc_control_pages(image, 0);
+		if (!image->swap_page) {
+			pr_err("Could not allocate swap buffer\n");
+			goto out_free_control_pages;
+		}
+	}
+
+	*rimage = image;
+	return 0;
+out_free_control_pages:
+	kimage_free_page_list(&image->control_pages);
+out_free_image:
+	kfree(image);
+	return ret;
+}
+
+static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
+		struct kexec_segment *segments, unsigned long flags)
+{
+	struct kimage **dest_image, *image;
+	unsigned long i;
+	int ret;
+
+	/*
+	 * Because we write directly to the reserved memory region when loading
+	 * crash kernels we need a serialization here to prevent multiple crash
+	 * kernels from attempting to load simultaneously.
+	 */
+	if (!kexec_trylock())
+		return -EBUSY;
+
+	if (flags & KEXEC_ON_CRASH) {
+		dest_image = &kexec_crash_image;
+		if (kexec_crash_image)
+			arch_kexec_unprotect_crashkres();
+	} else {
+		dest_image = &kexec_image;
+	}
+
+	if (nr_segments == 0) {
+		/* Uninstall image */
+		kimage_free(xchg(dest_image, NULL));
+		ret = 0;
+		goto out_unlock;
+	}
+	if (flags & KEXEC_ON_CRASH) {
+		/*
+		 * Loading another kernel to switch to if this one
+		 * crashes.  Free any current crash dump kernel before
+		 * we corrupt it.
+		 */
+		kimage_free(xchg(&kexec_crash_image, NULL));
+	}
+
+	ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
+	if (ret)
+		goto out_unlock;
+
+	if (flags & KEXEC_PRESERVE_CONTEXT)
+		image->preserve_context = 1;
+
+	ret = machine_kexec_prepare(image);
+	if (ret)
+		goto out;
+
+	/*
+	 * Some architecture(like S390) may touch the crash memory before
+	 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
+	 */
+	ret = kimage_crash_copy_vmcoreinfo(image);
+	if (ret)
+		goto out;
+
+	for (i = 0; i < nr_segments; i++) {
+		ret = kimage_load_segment(image, &image->segment[i]);
+		if (ret)
+			goto out;
+	}
+
+	kimage_terminate(image);
+
+	ret = machine_kexec_post_load(image);
+	if (ret)
+		goto out;
+
+	/* Install the new kernel and uninstall the old */
+	image = xchg(dest_image, image);
+
+out:
+	if ((flags & KEXEC_ON_CRASH) && kexec_crash_image)
+		arch_kexec_protect_crashkres();
+
+	kimage_free(image);
+out_unlock:
+	kexec_unlock();
+	return ret;
+}
+
+/*
+ * Exec Kernel system call: for obvious reasons only root may call it.
+ *
+ * This call breaks up into three pieces.
+ * - A generic part which loads the new kernel from the current
+ *   address space, and very carefully places the data in the
+ *   allocated pages.
+ *
+ * - A generic part that interacts with the kernel and tells all of
+ *   the devices to shut down.  Preventing on-going dmas, and placing
+ *   the devices in a consistent state so a later kernel can
+ *   reinitialize them.
+ *
+ * - A machine specific part that includes the syscall number
+ *   and then copies the image to it's final destination.  And
+ *   jumps into the image at entry.
+ *
+ * kexec does not sync, or unmount filesystems so if you need
+ * that to happen you need to do that yourself.
+ */
+
+static inline int kexec_load_check(unsigned long nr_segments,
+				   unsigned long flags)
+{
+	int result;
+
+	/* We only trust the superuser with rebooting the system. */
+	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
+		return -EPERM;
+
+	/* Permit LSMs and IMA to fail the kexec */
+	result = security_kernel_load_data(LOADING_KEXEC_IMAGE, false);
+	if (result < 0)
+		return result;
+
+	/*
+	 * kexec can be used to circumvent module loading restrictions, so
+	 * prevent loading in that case
+	 */
+	result = security_locked_down(LOCKDOWN_KEXEC);
+	if (result)
+		return result;
+
+	/*
+	 * Verify we have a legal set of flags
+	 * This leaves us room for future extensions.
+	 */
+	if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
+		return -EINVAL;
+
+	/* Put an artificial cap on the number
+	 * of segments passed to kexec_load.
+	 */
+	if (nr_segments > KEXEC_SEGMENT_MAX)
+		return -EINVAL;
+
+	return 0;
+}
+
+SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
+		struct kexec_segment __user *, segments, unsigned long, flags)
+{
+	struct kexec_segment *ksegments;
+	unsigned long result;
+
+	result = kexec_load_check(nr_segments, flags);
+	if (result)
+		return result;
+
+	/* Verify we are on the appropriate architecture */
+	if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
+		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
+		return -EINVAL;
+
+	ksegments = memdup_array_user(segments, nr_segments, sizeof(ksegments[0]));
+	if (IS_ERR(ksegments))
+		return PTR_ERR(ksegments);
+
+	result = do_kexec_load(entry, nr_segments, ksegments, flags);
+	kfree(ksegments);
+
+	return result;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
+		       compat_ulong_t, nr_segments,
+		       struct compat_kexec_segment __user *, segments,
+		       compat_ulong_t, flags)
+{
+	struct compat_kexec_segment in;
+	struct kexec_segment *ksegments;
+	unsigned long i, result;
+
+	result = kexec_load_check(nr_segments, flags);
+	if (result)
+		return result;
+
+	/* Don't allow clients that don't understand the native
+	 * architecture to do anything.
+	 */
+	if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
+		return -EINVAL;
+
+	ksegments = kmalloc_array(nr_segments, sizeof(ksegments[0]),
+			GFP_KERNEL);
+	if (!ksegments)
+		return -ENOMEM;
+
+	for (i = 0; i < nr_segments; i++) {
+		result = copy_from_user(&in, &segments[i], sizeof(in));
+		if (result)
+			goto fail;
+
+		ksegments[i].buf   = compat_ptr(in.buf);
+		ksegments[i].bufsz = in.bufsz;
+		ksegments[i].mem   = in.mem;
+		ksegments[i].memsz = in.memsz;
+	}
+
+	result = do_kexec_load(entry, nr_segments, ksegments, flags);
+
+fail:
+	kfree(ksegments);
+	return result;
+}
+#endif