// 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; #ifdef CONFIG_CRASH_HOTPLUG	if (flags & KEXEC_UPDATE_ELFCOREHDR)		image->update_elfcorehdr = 1;#endif 	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 image_type = (flags & KEXEC_ON_CRASH) ?			 KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;	int result; 	/* We only trust the superuser with rebooting the system. */	if (!kexec_load_permitted(image_type))		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_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_COMPATCOMPAT_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