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Commit 8be01882 authored by Philipp Rudo's avatar Philipp Rudo Committed by Martin Schwidefsky
Browse files

s390/kexec_file: Add ELF loader 



Add an ELF loader for kexec_file. The main task here is to do proper sanity
checks on the ELF file. Basically all other functionality was already
implemented for the image loader.

Signed-off-by: default avatarPhilipp Rudo <prudo@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ee337f54

arch/s390/include/asm/kexec.h

+1 −0
Original line number Diff line number Diff line
@@ -67,5 +67,6 @@ int *kexec_file_update_kernel(struct kimage *iamge, 
			      struct s390_load_data *data);



extern const struct kexec_file_ops s390_kexec_image_ops;

extern const struct kexec_file_ops s390_kexec_elf_ops;



#endif /*_S390_KEXEC_H */

arch/s390/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o 
obj-$(CONFIG_UPROBES)		+= uprobes.o



obj-$(CONFIG_KEXEC_FILE)	+= machine_kexec_file.o kexec_image.o

obj-$(CONFIG_KEXEC_FILE)	+= kexec_elf.o



obj-$(CONFIG_PERF_EVENTS)	+= perf_event.o perf_cpum_cf.o perf_cpum_sf.o

obj-$(CONFIG_PERF_EVENTS)	+= perf_cpum_cf_events.o perf_regs.o

arch/s390/kernel/kexec_elf.c

0 → 100644
+147 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * ELF loader for kexec_file_load system call.

 *

 * Copyright IBM Corp. 2018

 *

 * Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com>

 */



#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/kexec.h>

#include <asm/setup.h>



static int kexec_file_add_elf_kernel(struct kimage *image,

				     struct s390_load_data *data,

				     char *kernel, unsigned long kernel_len)

{

	struct kexec_buf buf;

	const Elf_Ehdr *ehdr;

	const Elf_Phdr *phdr;

	int i, ret;



	ehdr = (Elf_Ehdr *)kernel;

	buf.image = image;



	phdr = (void *)ehdr + ehdr->e_phoff;

	for (i = 0; i < ehdr->e_phnum; i++, phdr++) {

		if (phdr->p_type != PT_LOAD)

			continue;



		buf.buffer = kernel + phdr->p_offset;

		buf.bufsz = phdr->p_filesz;



		buf.mem = ALIGN(phdr->p_paddr, phdr->p_align);

		buf.memsz = phdr->p_memsz;



		if (phdr->p_paddr == 0) {

			data->kernel_buf = buf.buffer;

			data->memsz += STARTUP_NORMAL_OFFSET;



			buf.buffer += STARTUP_NORMAL_OFFSET;

			buf.bufsz -= STARTUP_NORMAL_OFFSET;



			buf.mem += STARTUP_NORMAL_OFFSET;

			buf.memsz -= STARTUP_NORMAL_OFFSET;

		}



		if (image->type == KEXEC_TYPE_CRASH)

			buf.mem += crashk_res.start;



		ret = kexec_add_buffer(&buf);

		if (ret)

			return ret;



		data->memsz += buf.memsz;

	}



	return 0;

}



static void *s390_elf_load(struct kimage *image,

			   char *kernel, unsigned long kernel_len,

			   char *initrd, unsigned long initrd_len,

			   char *cmdline, unsigned long cmdline_len)

{

	struct s390_load_data data = {0};

	const Elf_Ehdr *ehdr;

	const Elf_Phdr *phdr;

	size_t size;

	int i, ret;



	/* image->fobs->probe already checked for valid ELF magic number. */

	ehdr = (Elf_Ehdr *)kernel;



	if (ehdr->e_type != ET_EXEC ||

	    ehdr->e_ident[EI_CLASS] != ELFCLASS64 ||

	    !elf_check_arch(ehdr))

		return ERR_PTR(-EINVAL);



	if (!ehdr->e_phnum || ehdr->e_phentsize != sizeof(Elf_Phdr))

		return ERR_PTR(-EINVAL);



	size = ehdr->e_ehsize + ehdr->e_phoff;

	size += ehdr->e_phentsize * ehdr->e_phnum;

	if (size > kernel_len)

		return ERR_PTR(-EINVAL);



	phdr = (void *)ehdr + ehdr->e_phoff;

	size = ALIGN(size, phdr->p_align);

	for (i = 0; i < ehdr->e_phnum; i++, phdr++) {

		if (phdr->p_type == PT_INTERP)

			return ERR_PTR(-EINVAL);



		if (phdr->p_offset > kernel_len)

			return ERR_PTR(-EINVAL);



		size += ALIGN(phdr->p_filesz, phdr->p_align);

	}



	if (size > kernel_len)

		return ERR_PTR(-EINVAL);



	ret = kexec_file_add_elf_kernel(image, &data, kernel, kernel_len);

	if (ret)

		return ERR_PTR(ret);



	if (!data.memsz)

		return ERR_PTR(-EINVAL);



	if (initrd) {

		ret = kexec_file_add_initrd(image, &data, initrd, initrd_len);

		if (ret)

			return ERR_PTR(ret);

	}



	ret = kexec_file_add_purgatory(image, &data);

	if (ret)

		return ERR_PTR(ret);



	return kexec_file_update_kernel(image, &data);

}



static int s390_elf_probe(const char *buf, unsigned long len)

{

	const Elf_Ehdr *ehdr;



	if (len < sizeof(Elf_Ehdr))

		return -ENOEXEC;



	ehdr = (Elf_Ehdr *)buf;



	/* Only check the ELF magic number here and do proper validity check

	 * in the loader. Any check here that fails would send the erroneous

	 * ELF file to the image loader that does not care what it gets.

	 * (Most likely) causing behavior not intended by the user.

	 */

	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)

		return -ENOEXEC;



	return 0;

}



const struct kexec_file_ops s390_kexec_elf_ops = {

	.probe = s390_elf_probe,

	.load = s390_elf_load,

};

arch/s390/kernel/machine_kexec_file.c

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <asm/setup.h>



const struct kexec_file_ops * const kexec_file_loaders[] = {

	&s390_kexec_elf_ops,

	&s390_kexec_image_ops,

	NULL,

};