https://github.com/torvalds/linux
Tip revision: 5ed02dbb497422bf225783f46e6eadd237d23d6b authored by Linus Torvalds on 29 May 2017, 00:20:53 UTC
Linux 4.12-rc3
Linux 4.12-rc3
Tip revision: 5ed02db
kexec_elf_64.c
/*
* Load ELF vmlinux file for the kexec_file_load syscall.
*
* Copyright (C) 2004 Adam Litke (agl@us.ibm.com)
* Copyright (C) 2004 IBM Corp.
* Copyright (C) 2005 R Sharada (sharada@in.ibm.com)
* Copyright (C) 2006 Mohan Kumar M (mohan@in.ibm.com)
* Copyright (C) 2016 IBM Corporation
*
* Based on kexec-tools' kexec-elf-exec.c and kexec-elf-ppc64.c.
* Heavily modified for the kernel by
* Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation (version 2 of the License).
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) "kexec_elf: " fmt
#include <linux/elf.h>
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/module.h>
#include <linux/of_fdt.h>
#include <linux/slab.h>
#include <linux/types.h>
#define PURGATORY_STACK_SIZE (16 * 1024)
#define elf_addr_to_cpu elf64_to_cpu
#ifndef Elf_Rel
#define Elf_Rel Elf64_Rel
#endif /* Elf_Rel */
struct elf_info {
/*
* Where the ELF binary contents are kept.
* Memory managed by the user of the struct.
*/
const char *buffer;
const struct elfhdr *ehdr;
const struct elf_phdr *proghdrs;
struct elf_shdr *sechdrs;
};
static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
{
return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
}
static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
{
if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
value = le64_to_cpu(value);
else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
value = be64_to_cpu(value);
return value;
}
static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
{
if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
value = le16_to_cpu(value);
else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
value = be16_to_cpu(value);
return value;
}
static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
{
if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
value = le32_to_cpu(value);
else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
value = be32_to_cpu(value);
return value;
}
/**
* elf_is_ehdr_sane - check that it is safe to use the ELF header
* @buf_len: size of the buffer in which the ELF file is loaded.
*/
static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
{
if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
pr_debug("Bad program header size.\n");
return false;
} else if (ehdr->e_shnum > 0 &&
ehdr->e_shentsize != sizeof(struct elf_shdr)) {
pr_debug("Bad section header size.\n");
return false;
} else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
ehdr->e_version != EV_CURRENT) {
pr_debug("Unknown ELF version.\n");
return false;
}
if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
size_t phdr_size;
/*
* e_phnum is at most 65535 so calculating the size of the
* program header cannot overflow.
*/
phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
/* Sanity check the program header table location. */
if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
pr_debug("Program headers at invalid location.\n");
return false;
} else if (ehdr->e_phoff + phdr_size > buf_len) {
pr_debug("Program headers truncated.\n");
return false;
}
}
if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
size_t shdr_size;
/*
* e_shnum is at most 65536 so calculating
* the size of the section header cannot overflow.
*/
shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
/* Sanity check the section header table location. */
if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
pr_debug("Section headers at invalid location.\n");
return false;
} else if (ehdr->e_shoff + shdr_size > buf_len) {
pr_debug("Section headers truncated.\n");
return false;
}
}
return true;
}
static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
{
struct elfhdr *buf_ehdr;
if (len < sizeof(*buf_ehdr)) {
pr_debug("Buffer is too small to hold ELF header.\n");
return -ENOEXEC;
}
memset(ehdr, 0, sizeof(*ehdr));
memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
if (!elf_is_elf_file(ehdr)) {
pr_debug("No ELF header magic.\n");
return -ENOEXEC;
}
if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
pr_debug("Not a supported ELF class.\n");
return -ENOEXEC;
} else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
pr_debug("Not a supported ELF data format.\n");
return -ENOEXEC;
}
buf_ehdr = (struct elfhdr *) buf;
if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
pr_debug("Bad ELF header size.\n");
return -ENOEXEC;
}
ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
}
/**
* elf_is_phdr_sane - check that it is safe to use the program header
* @buf_len: size of the buffer in which the ELF file is loaded.
*/
static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
{
if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
pr_debug("ELF segment location wraps around.\n");
return false;
} else if (phdr->p_offset + phdr->p_filesz > buf_len) {
pr_debug("ELF segment not in file.\n");
return false;
} else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
pr_debug("ELF segment address wraps around.\n");
return false;
}
return true;
}
static int elf_read_phdr(const char *buf, size_t len, struct elf_info *elf_info,
int idx)
{
/* Override the const in proghdrs, we are the ones doing the loading. */
struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
const char *pbuf;
struct elf_phdr *buf_phdr;
pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
buf_phdr = (struct elf_phdr *) pbuf;
phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
/*
* The following fields have a type equivalent to Elf_Addr
* both in 32 bit and 64 bit ELF.
*/
phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
}
/**
* elf_read_phdrs - read the program headers from the buffer
*
* This function assumes that the program header table was checked for sanity.
* Use elf_is_ehdr_sane() if it wasn't.
*/
static int elf_read_phdrs(const char *buf, size_t len,
struct elf_info *elf_info)
{
size_t phdr_size, i;
const struct elfhdr *ehdr = elf_info->ehdr;
/*
* e_phnum is at most 65535 so calculating the size of the
* program header cannot overflow.
*/
phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
if (!elf_info->proghdrs)
return -ENOMEM;
for (i = 0; i < ehdr->e_phnum; i++) {
int ret;
ret = elf_read_phdr(buf, len, elf_info, i);
if (ret) {
kfree(elf_info->proghdrs);
elf_info->proghdrs = NULL;
return ret;
}
}
return 0;
}
/**
* elf_is_shdr_sane - check that it is safe to use the section header
* @buf_len: size of the buffer in which the ELF file is loaded.
*/
static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
{
bool size_ok;
/* SHT_NULL headers have undefined values, so we can't check them. */
if (shdr->sh_type == SHT_NULL)
return true;
/* Now verify sh_entsize */
switch (shdr->sh_type) {
case SHT_SYMTAB:
size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
break;
case SHT_RELA:
size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
break;
case SHT_DYNAMIC:
size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
break;
case SHT_REL:
size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
break;
case SHT_NOTE:
case SHT_PROGBITS:
case SHT_HASH:
case SHT_NOBITS:
default:
/*
* This is a section whose entsize requirements
* I don't care about. If I don't know about
* the section I can't care about it's entsize
* requirements.
*/
size_ok = true;
break;
}
if (!size_ok) {
pr_debug("ELF section with wrong entry size.\n");
return false;
} else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
pr_debug("ELF section address wraps around.\n");
return false;
}
if (shdr->sh_type != SHT_NOBITS) {
if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
pr_debug("ELF section location wraps around.\n");
return false;
} else if (shdr->sh_offset + shdr->sh_size > buf_len) {
pr_debug("ELF section not in file.\n");
return false;
}
}
return true;
}
static int elf_read_shdr(const char *buf, size_t len, struct elf_info *elf_info,
int idx)
{
struct elf_shdr *shdr = &elf_info->sechdrs[idx];
const struct elfhdr *ehdr = elf_info->ehdr;
const char *sbuf;
struct elf_shdr *buf_shdr;
sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
buf_shdr = (struct elf_shdr *) sbuf;
shdr->sh_name = elf32_to_cpu(ehdr, buf_shdr->sh_name);
shdr->sh_type = elf32_to_cpu(ehdr, buf_shdr->sh_type);
shdr->sh_addr = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
shdr->sh_offset = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
shdr->sh_link = elf32_to_cpu(ehdr, buf_shdr->sh_link);
shdr->sh_info = elf32_to_cpu(ehdr, buf_shdr->sh_info);
/*
* The following fields have a type equivalent to Elf_Addr
* both in 32 bit and 64 bit ELF.
*/
shdr->sh_flags = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
shdr->sh_size = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
shdr->sh_entsize = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
}
/**
* elf_read_shdrs - read the section headers from the buffer
*
* This function assumes that the section header table was checked for sanity.
* Use elf_is_ehdr_sane() if it wasn't.
*/
static int elf_read_shdrs(const char *buf, size_t len,
struct elf_info *elf_info)
{
size_t shdr_size, i;
/*
* e_shnum is at most 65536 so calculating
* the size of the section header cannot overflow.
*/
shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
if (!elf_info->sechdrs)
return -ENOMEM;
for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
int ret;
ret = elf_read_shdr(buf, len, elf_info, i);
if (ret) {
kfree(elf_info->sechdrs);
elf_info->sechdrs = NULL;
return ret;
}
}
return 0;
}
/**
* elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
* @buf: Buffer to read ELF file from.
* @len: Size of @buf.
* @ehdr: Pointer to existing struct which will be populated.
* @elf_info: Pointer to existing struct which will be populated.
*
* This function allows reading ELF files with different byte order than
* the kernel, byte-swapping the fields as needed.
*
* Return:
* On success returns 0, and the caller should call elf_free_info(elf_info) to
* free the memory allocated for the section and program headers.
*/
int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
struct elf_info *elf_info)
{
int ret;
ret = elf_read_ehdr(buf, len, ehdr);
if (ret)
return ret;
elf_info->buffer = buf;
elf_info->ehdr = ehdr;
if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
ret = elf_read_phdrs(buf, len, elf_info);
if (ret)
return ret;
}
if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
ret = elf_read_shdrs(buf, len, elf_info);
if (ret) {
kfree(elf_info->proghdrs);
return ret;
}
}
return 0;
}
/**
* elf_free_info - free memory allocated by elf_read_from_buffer
*/
void elf_free_info(struct elf_info *elf_info)
{
kfree(elf_info->proghdrs);
kfree(elf_info->sechdrs);
memset(elf_info, 0, sizeof(*elf_info));
}
/**
* build_elf_exec_info - read ELF executable and check that we can use it
*/
static int build_elf_exec_info(const char *buf, size_t len, struct elfhdr *ehdr,
struct elf_info *elf_info)
{
int i;
int ret;
ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
if (ret)
return ret;
/* Big endian vmlinux has type ET_DYN. */
if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
pr_err("Not an ELF executable.\n");
goto error;
} else if (!elf_info->proghdrs) {
pr_err("No ELF program header.\n");
goto error;
}
for (i = 0; i < ehdr->e_phnum; i++) {
/*
* Kexec does not support loading interpreters.
* In addition this check keeps us from attempting
* to kexec ordinay executables.
*/
if (elf_info->proghdrs[i].p_type == PT_INTERP) {
pr_err("Requires an ELF interpreter.\n");
goto error;
}
}
return 0;
error:
elf_free_info(elf_info);
return -ENOEXEC;
}
static int elf64_probe(const char *buf, unsigned long len)
{
struct elfhdr ehdr;
struct elf_info elf_info;
int ret;
ret = build_elf_exec_info(buf, len, &ehdr, &elf_info);
if (ret)
return ret;
elf_free_info(&elf_info);
return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
}
/**
* elf_exec_load - load ELF executable image
* @lowest_load_addr: On return, will be the address where the first PT_LOAD
* section will be loaded in memory.
*
* Return:
* 0 on success, negative value on failure.
*/
static int elf_exec_load(struct kimage *image, struct elfhdr *ehdr,
struct elf_info *elf_info,
unsigned long *lowest_load_addr)
{
unsigned long base = 0, lowest_addr = UINT_MAX;
int ret;
size_t i;
struct kexec_buf kbuf = { .image = image, .buf_max = ppc64_rma_size,
.top_down = false };
/* Read in the PT_LOAD segments. */
for (i = 0; i < ehdr->e_phnum; i++) {
unsigned long load_addr;
size_t size;
const struct elf_phdr *phdr;
phdr = &elf_info->proghdrs[i];
if (phdr->p_type != PT_LOAD)
continue;
size = phdr->p_filesz;
if (size > phdr->p_memsz)
size = phdr->p_memsz;
kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
kbuf.bufsz = size;
kbuf.memsz = phdr->p_memsz;
kbuf.buf_align = phdr->p_align;
kbuf.buf_min = phdr->p_paddr + base;
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out;
load_addr = kbuf.mem;
if (load_addr < lowest_addr)
lowest_addr = load_addr;
}
/* Update entry point to reflect new load address. */
ehdr->e_entry += base;
*lowest_load_addr = lowest_addr;
ret = 0;
out:
return ret;
}
static void *elf64_load(struct kimage *image, char *kernel_buf,
unsigned long kernel_len, char *initrd,
unsigned long initrd_len, char *cmdline,
unsigned long cmdline_len)
{
int ret;
unsigned int fdt_size;
unsigned long kernel_load_addr, purgatory_load_addr;
unsigned long initrd_load_addr = 0, fdt_load_addr;
void *fdt;
const void *slave_code;
struct elfhdr ehdr;
struct elf_info elf_info;
struct kexec_buf kbuf = { .image = image, .buf_min = 0,
.buf_max = ppc64_rma_size };
ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
if (ret)
goto out;
ret = elf_exec_load(image, &ehdr, &elf_info, &kernel_load_addr);
if (ret)
goto out;
pr_debug("Loaded the kernel at 0x%lx\n", kernel_load_addr);
ret = kexec_load_purgatory(image, 0, ppc64_rma_size, true,
&purgatory_load_addr);
if (ret) {
pr_err("Loading purgatory failed.\n");
goto out;
}
pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
if (initrd != NULL) {
kbuf.buffer = initrd;
kbuf.bufsz = kbuf.memsz = initrd_len;
kbuf.buf_align = PAGE_SIZE;
kbuf.top_down = false;
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out;
initrd_load_addr = kbuf.mem;
pr_debug("Loaded initrd at 0x%lx\n", initrd_load_addr);
}
fdt_size = fdt_totalsize(initial_boot_params) * 2;
fdt = kmalloc(fdt_size, GFP_KERNEL);
if (!fdt) {
pr_err("Not enough memory for the device tree.\n");
ret = -ENOMEM;
goto out;
}
ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
if (ret < 0) {
pr_err("Error setting up the new device tree.\n");
ret = -EINVAL;
goto out;
}
ret = setup_new_fdt(image, fdt, initrd_load_addr, initrd_len, cmdline);
if (ret)
goto out;
fdt_pack(fdt);
kbuf.buffer = fdt;
kbuf.bufsz = kbuf.memsz = fdt_size;
kbuf.buf_align = PAGE_SIZE;
kbuf.top_down = true;
ret = kexec_add_buffer(&kbuf);
if (ret)
goto out;
fdt_load_addr = kbuf.mem;
pr_debug("Loaded device tree at 0x%lx\n", fdt_load_addr);
slave_code = elf_info.buffer + elf_info.proghdrs[0].p_offset;
ret = setup_purgatory(image, slave_code, fdt, kernel_load_addr,
fdt_load_addr);
if (ret)
pr_err("Error setting up the purgatory.\n");
out:
elf_free_info(&elf_info);
/* Make kimage_file_post_load_cleanup free the fdt buffer for us. */
return ret ? ERR_PTR(ret) : fdt;
}
struct kexec_file_ops kexec_elf64_ops = {
.probe = elf64_probe,
.load = elf64_load,
};