- 根目录:
- kernel
- kexec_file.c
/*
* kexec: kexec_file_load system call
*
* Copyright (C) 2014 Red Hat Inc.
* Authors:
* Vivek Goyal <vgoyal@redhat.com>
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/kexec.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>
#include "kexec_internal.h"
/*
* Declare these symbols weak so that if architecture provides a purgatory,
* these will be overridden.
*/
char __weak kexec_purgatory[0];
size_t __weak kexec_purgatory_size = 0;
static int kexec_calculate_store_digests(struct kimage *image);
static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len)
{
struct fd f = fdget(fd);
int ret;
struct kstat stat;
loff_t pos;
ssize_t bytes = 0;
if (!f.file)
return -EBADF;
ret = vfs_getattr(&f.file->f_path, &stat);
if (ret)
goto out;
if (stat.size > INT_MAX) {
ret = -EFBIG;
goto out;
}
/* Don't hand 0 to vmalloc, it whines. */
if (stat.size == 0) {
ret = -EINVAL;
goto out;
}
*buf = vmalloc(stat.size);
if (!*buf) {
ret = -ENOMEM;
goto out;
}
pos = 0;
while (pos < stat.size) {
bytes = kernel_read(f.file, pos, (char *)(*buf) + pos,
stat.size - pos);
if (bytes < 0) {
vfree(*buf);
ret = bytes;
goto out;
}
if (bytes == 0)
break;
pos += bytes;
}
if (pos != stat.size) {
ret = -EBADF;
vfree(*buf);
goto out;
}
*buf_len = pos;
out:
fdput(f);
return ret;
}
/* Architectures can provide this probe function */
int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
unsigned long buf_len)
{
return -ENOEXEC;
}
void * __weak arch_kexec_kernel_image_load(struct kimage *image)
{
return ERR_PTR(-ENOEXEC);
}
int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
{
return -EINVAL;
}
int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
unsigned long buf_len)
{
return -EKEYREJECTED;
}
/* Apply relocations of type RELA */
int __weak
arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
{
pr_err("RELA relocation unsupported.\n");
return -ENOEXEC;
}
/* Apply relocations of type REL */
int __weak
arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
unsigned int relsec)
{
pr_err("REL relocation unsupported.\n");
return -ENOEXEC;
}
/*
* Free up memory used by kernel, initrd, and command line. This is temporary
* memory allocation which is not needed any more after these buffers have
* been loaded into separate segments and have been copied elsewhere.
*/
void kimage_file_post_load_cleanup(struct kimage *image)
{
struct purgatory_info *pi = &image->purgatory_info;
vfree(image->kernel_buf);
image->kernel_buf = NULL;
vfree(image->initrd_buf);
image->initrd_buf = NULL;
kfree(image->cmdline_buf);
image->cmdline_buf = NULL;
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
vfree(pi->sechdrs);
pi->sechdrs = NULL;
/* See if architecture has anything to cleanup post load */
arch_kimage_file_post_load_cleanup(image);
/*
* Above call should have called into bootloader to free up
* any data stored in kimage->image_loader_data. It should
* be ok now to free it up.
*/
kfree(image->image_loader_data);
image->image_loader_data = NULL;
}
/*
* In file mode list of segments is prepared by kernel. Copy relevant
* data from user space, do error checking, prepare segment list
*/
static int
kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
const char __user *cmdline_ptr,
unsigned long cmdline_len, unsigned flags)
{
int ret = 0;
void *ldata;
ret = copy_file_from_fd(kernel_fd, &image->kernel_buf,
&image->kernel_buf_len);
if (ret)
return ret;
/* Call arch image probe handlers */
ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
image->kernel_buf_len);
if (ret)
goto out;
#ifdef CONFIG_KEXEC_VERIFY_SIG
ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
image->kernel_buf_len);
if (ret) {
pr_debug("kernel signature verification failed.\n");
goto out;
}
pr_debug("kernel signature verification successful.\n");
#endif
/* It is possible that there no initramfs is being loaded */
if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
ret = copy_file_from_fd(initrd_fd, &image->initrd_buf,
&image->initrd_buf_len);
if (ret)
goto out;
}
if (cmdline_len) {
image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL);
if (!image->cmdline_buf) {
ret = -ENOMEM;
goto out;
}
ret = copy_from_user(image->cmdline_buf, cmdline_ptr,
cmdline_len);
if (ret) {
ret = -EFAULT;
goto out;
}
image->cmdline_buf_len = cmdline_len;
/* command line should be a string with last byte null */
if (image->cmdline_buf[cmdline_len - 1] != '\0') {
ret = -EINVAL;
goto out;
}
}
/* Call arch image load handlers */
ldata = arch_kexec_kernel_image_load(image);
if (IS_ERR(ldata)) {
ret = PTR_ERR(ldata);
goto out;
}
image->image_loader_data = ldata;
out:
/* In case of error, free up all allocated memory in this function */
if (ret)
kimage_file_post_load_cleanup(image);
return ret;
}
static int
kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
int initrd_fd, const char __user *cmdline_ptr,
unsigned long cmdline_len, unsigned long flags)
{
int ret;
struct kimage *image;
bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
image = do_kimage_alloc_init();
if (!image)
return -ENOMEM;
image->file_mode = 1;
if (kexec_on_panic) {
/* Enable special crash kernel control page alloc policy. */
image->control_page = crashk_res.start;
image->type = KEXEC_TYPE_CRASH;
}
ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
cmdline_ptr, cmdline_len, flags);
if (ret)
goto out_free_image;
ret = sanity_check_segment_list(image);
if (ret)
goto out_free_post_load_bufs;
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_post_load_bufs;
}
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_post_load_bufs:
kimage_file_post_load_cleanup(image);
out_free_image:
kfree(image);
return ret;
}
SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
unsigned long, cmdline_len, const char __user *, cmdline_ptr,
unsigned long, flags)
{
int ret = 0, i;
struct kimage **dest_image, *image;
/* We only trust the superuser with rebooting the system. */
if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
return -EPERM;
/* Make sure we have a legal set of flags */
if (flags != (flags & KEXEC_FILE_FLAGS))
return -EINVAL;
image = NULL;
if (!mutex_trylock(&kexec_mutex))
return -EBUSY;
dest_image = &kexec_image;
if (flags & KEXEC_FILE_ON_CRASH)
dest_image = &kexec_crash_image;
if (flags & KEXEC_FILE_UNLOAD)
goto exchange;
/*
* In case of crash, new kernel gets loaded in reserved region. It is
* same memory where old crash kernel might be loaded. Free any
* current crash dump kernel before we corrupt it.
*/
if (flags & KEXEC_FILE_ON_CRASH)
kimage_free(xchg(&kexec_crash_image, NULL));
ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
cmdline_len, flags);
if (ret)
goto out;
ret = machine_kexec_prepare(image);
if (ret)
goto out;
ret = kexec_calculate_store_digests(image);
if (ret)
goto out;
for (i = 0; i < image->nr_segments; i++) {
struct kexec_segment *ksegment;
ksegment = &image->segment[i];
pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
i, ksegment->buf, ksegment->bufsz, ksegment->mem,
ksegment->memsz);
ret = kimage_load_segment(image, &image->segment[i]);
if (ret)
goto out;
}
kimage_terminate(image);
/*
* Free up any temporary buffers allocated which are not needed
* after image has been loaded
*/
kimage_file_post_load_cleanup(image);
exchange:
image = xchg(dest_image, image);
out:
mutex_unlock(&kexec_mutex);
kimage_free(image);
return ret;
}
static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
struct kexec_buf *kbuf)
{
struct kimage *image = kbuf->image;
unsigned long temp_start, temp_end;
temp_end = min(end, kbuf->buf_max);
temp_start = temp_end - kbuf->memsz;
do {
/* align down start */
temp_start = temp_start & (~(kbuf->buf_align - 1));
if (temp_start < start || temp_start < kbuf->buf_min)
return 0;
temp_end = temp_start + kbuf->memsz - 1;
/*
* Make sure this does not conflict with any of existing
* segments
*/
if (kimage_is_destination_range(image, temp_start, temp_end)) {
temp_start = temp_start - PAGE_SIZE;
continue;
}
/* We found a suitable memory range */
break;
} while (1);
/* If we are here, we found a suitable memory range */
kbuf->mem = temp_start;
/* Success, stop navigating through remaining System RAM ranges */
return 1;
}
static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
struct kexec_buf *kbuf)
{
struct kimage *image = kbuf->image;
unsigned long temp_start, temp_end;
temp_start = max(start, kbuf->buf_min);
do {
temp_start = ALIGN(temp_start, kbuf->buf_align);
temp_end = temp_start + kbuf->memsz - 1;
if (temp_end > end || temp_end > kbuf->buf_max)
return 0;
/*
* Make sure this does not conflict with any of existing
* segments
*/
if (kimage_is_destination_range(image, temp_start, temp_end)) {
temp_start = temp_start + PAGE_SIZE;
continue;
}
/* We found a suitable memory range */
break;
} while (1);
/* If we are here, we found a suitable memory range */
kbuf->mem = temp_start;
/* Success, stop navigating through remaining System RAM ranges */
return 1;
}
static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
{
struct kexec_buf *kbuf = (struct kexec_buf *)arg;
unsigned long sz = end - start + 1;
/* Returning 0 will take to next memory range */
if (sz < kbuf->memsz)
return 0;
if (end < kbuf->buf_min || start > kbuf->buf_max)
return 0;
/*
* Allocate memory top down with-in ram range. Otherwise bottom up
* allocation.
*/
if (kbuf->top_down)
return locate_mem_hole_top_down(start, end, kbuf);
return locate_mem_hole_bottom_up(start, end, kbuf);
}
/*
* Helper function for placing a buffer in a kexec segment. This assumes
* that kexec_mutex is held.
*/
int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
unsigned long memsz, unsigned long buf_align,
unsigned long buf_min, unsigned long buf_max,
bool top_down, unsigned long *load_addr)
{
struct kexec_segment *ksegment;
struct kexec_buf buf, *kbuf;
int ret;
/* Currently adding segment this way is allowed only in file mode */
if (!image->file_mode)
return -EINVAL;
if (image->nr_segments >= KEXEC_SEGMENT_MAX)
return -EINVAL;
/*
* Make sure we are not trying to add buffer after allocating
* control pages. All segments need to be placed first before
* any control pages are allocated. As control page allocation
* logic goes through list of segments to make sure there are
* no destination overlaps.
*/
if (!list_empty(&image->control_pages)) {
WARN_ON(1);
return -EINVAL;
}
memset(&buf, 0, sizeof(struct kexec_buf));
kbuf = &buf;
kbuf->image = image;
kbuf->buffer = buffer;
kbuf->bufsz = bufsz;
kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
kbuf->buf_align = max(buf_align, PAGE_SIZE);
kbuf->buf_min = buf_min;
kbuf->buf_max = buf_max;
kbuf->top_down = top_down;
/* Walk the RAM ranges and allocate a suitable range for the buffer */
if (image->type == KEXEC_TYPE_CRASH)
ret = walk_iomem_res("Crash kernel",
IORESOURCE_MEM | IORESOURCE_BUSY,
crashk_res.start, crashk_res.end, kbuf,
locate_mem_hole_callback);
else
ret = walk_system_ram_res(0, -1, kbuf,
locate_mem_hole_callback);
if (ret != 1) {
/* A suitable memory range could not be found for buffer */
return -EADDRNOTAVAIL;
}
/* Found a suitable memory range */
ksegment = &image->segment[image->nr_segments];
ksegment->kbuf = kbuf->buffer;
ksegment->bufsz = kbuf->bufsz;
ksegment->mem = kbuf->mem;
ksegment->memsz = kbuf->memsz;
image->nr_segments++;
*load_addr = ksegment->mem;
return 0;
}
/* Calculate and store the digest of segments */
static int kexec_calculate_store_digests(struct kimage *image)
{
struct crypto_shash *tfm;
struct shash_desc *desc;
int ret = 0, i, j, zero_buf_sz, sha_region_sz;
size_t desc_size, nullsz;
char *digest;
void *zero_buf;
struct kexec_sha_region *sha_regions;
struct purgatory_info *pi = &image->purgatory_info;
zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
zero_buf_sz = PAGE_SIZE;
tfm = crypto_alloc_shash("sha256", 0, 0);
if (IS_ERR(tfm)) {
ret = PTR_ERR(tfm);
goto out;
}
desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
desc = kzalloc(desc_size, GFP_KERNEL);
if (!desc) {
ret = -ENOMEM;
goto out_free_tfm;
}
sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
sha_regions = vzalloc(sha_region_sz);
if (!sha_regions)
goto out_free_desc;
desc->tfm = tfm;
desc->flags = 0;
ret = crypto_shash_init(desc);
if (ret < 0)
goto out_free_sha_regions;
digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
if (!digest) {
ret = -ENOMEM;
goto out_free_sha_regions;
}
for (j = i = 0; i < image->nr_segments; i++) {
struct kexec_segment *ksegment;
ksegment = &image->segment[i];
/*
* Skip purgatory as it will be modified once we put digest
* info in purgatory.
*/
if (ksegment->kbuf == pi->purgatory_buf)
continue;
ret = crypto_shash_update(desc, ksegment->kbuf,
ksegment->bufsz);
if (ret)
break;
/*
* Assume rest of the buffer is filled with zero and
* update digest accordingly.
*/
nullsz = ksegment->memsz - ksegment->bufsz;
while (nullsz) {
unsigned long bytes = nullsz;
if (bytes > zero_buf_sz)
bytes = zero_buf_sz;
ret = crypto_shash_update(desc, zero_buf, bytes);
if (ret)
break;
nullsz -= bytes;
}
if (ret)
break;
sha_regions[j].start = ksegment->mem;
sha_regions[j].len = ksegment->memsz;
j++;
}
if (!ret) {
ret = crypto_shash_final(desc, digest);
if (ret)
goto out_free_digest;
ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
sha_regions, sha_region_sz, 0);
if (ret)
goto out_free_digest;
ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
digest, SHA256_DIGEST_SIZE, 0);
if (ret)
goto out_free_digest;
}
out_free_digest:
kfree(digest);
out_free_sha_regions:
vfree(sha_regions);
out_free_desc:
kfree(desc);
out_free_tfm:
kfree(tfm);
out:
return ret;
}
/* Actually load purgatory. Lot of code taken from kexec-tools */
static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down)
{
struct purgatory_info *pi = &image->purgatory_info;
unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
unsigned char *buf_addr, *src;
int i, ret = 0, entry_sidx = -1;
const Elf_Shdr *sechdrs_c;
Elf_Shdr *sechdrs = NULL;
void *purgatory_buf = NULL;
/*
* sechdrs_c points to section headers in purgatory and are read
* only. No modifications allowed.
*/
sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
/*
* We can not modify sechdrs_c[] and its fields. It is read only.
* Copy it over to a local copy where one can store some temporary
* data and free it at the end. We need to modify ->sh_addr and
* ->sh_offset fields to keep track of permanent and temporary
* locations of sections.
*/
sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
if (!sechdrs)
return -ENOMEM;
memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
/*
* We seem to have multiple copies of sections. First copy is which
* is embedded in kernel in read only section. Some of these sections
* will be copied to a temporary buffer and relocated. And these
* sections will finally be copied to their final destination at
* segment load time.
*
* Use ->sh_offset to reflect section address in memory. It will
* point to original read only copy if section is not allocatable.
* Otherwise it will point to temporary copy which will be relocated.
*
* Use ->sh_addr to contain final address of the section where it
* will go during execution time.
*/
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (sechdrs[i].sh_type == SHT_NOBITS)
continue;
sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
sechdrs[i].sh_offset;
}
/*
* Identify entry point section and make entry relative to section
* start.
*/
entry = pi->ehdr->e_entry;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
continue;
/* Make entry section relative */
if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
pi->ehdr->e_entry)) {
entry_sidx = i;
entry -= sechdrs[i].sh_addr;
break;
}
}
/* Determine how much memory is needed to load relocatable object. */
buf_align = 1;
bss_align = 1;
buf_sz = 0;
bss_sz = 0;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
align = sechdrs[i].sh_addralign;
if (sechdrs[i].sh_type != SHT_NOBITS) {
if (buf_align < align)
buf_align = align;
buf_sz = ALIGN(buf_sz, align);
buf_sz += sechdrs[i].sh_size;
} else {
/* bss section */
if (bss_align < align)
bss_align = align;
bss_sz = ALIGN(bss_sz, align);
bss_sz += sechdrs[i].sh_size;
}
}
/* Determine the bss padding required to align bss properly */
bss_pad = 0;
if (buf_sz & (bss_align - 1))
bss_pad = bss_align - (buf_sz & (bss_align - 1));
memsz = buf_sz + bss_pad + bss_sz;
/* Allocate buffer for purgatory */
purgatory_buf = vzalloc(buf_sz);
if (!purgatory_buf) {
ret = -ENOMEM;
goto out;
}
if (buf_align < bss_align)
buf_align = bss_align;
/* Add buffer to segment list */
ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
buf_align, min, max, top_down,
&pi->purgatory_load_addr);
if (ret)
goto out;
/* Load SHF_ALLOC sections */
buf_addr = purgatory_buf;
load_addr = curr_load_addr = pi->purgatory_load_addr;
bss_addr = load_addr + buf_sz + bss_pad;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
align = sechdrs[i].sh_addralign;
if (sechdrs[i].sh_type != SHT_NOBITS) {
curr_load_addr = ALIGN(curr_load_addr, align);
offset = curr_load_addr - load_addr;
/* We already modifed ->sh_offset to keep src addr */
src = (char *) sechdrs[i].sh_offset;
memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
/* Store load address and source address of section */
sechdrs[i].sh_addr = curr_load_addr;
/*
* This section got copied to temporary buffer. Update
* ->sh_offset accordingly.
*/
sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
/* Advance to the next address */
curr_load_addr += sechdrs[i].sh_size;
} else {
bss_addr = ALIGN(bss_addr, align);
sechdrs[i].sh_addr = bss_addr;
bss_addr += sechdrs[i].sh_size;
}
}
/* Update entry point based on load address of text section */
if (entry_sidx >= 0)
entry += sechdrs[entry_sidx].sh_addr;
/* Make kernel jump to purgatory after shutdown */
image->start = entry;
/* Used later to get/set symbol values */
pi->sechdrs = sechdrs;
/*
* Used later to identify which section is purgatory and skip it
* from checksumming.
*/
pi->purgatory_buf = purgatory_buf;
return ret;
out:
vfree(sechdrs);
vfree(purgatory_buf);
return ret;
}
static int kexec_apply_relocations(struct kimage *image)
{
int i, ret;
struct purgatory_info *pi = &image->purgatory_info;
Elf_Shdr *sechdrs = pi->sechdrs;
/* Apply relocations */
for (i = 0; i < pi->ehdr->e_shnum; i++) {
Elf_Shdr *section, *symtab;
if (sechdrs[i].sh_type != SHT_RELA &&
sechdrs[i].sh_type != SHT_REL)
continue;
/*
* For section of type SHT_RELA/SHT_REL,
* ->sh_link contains section header index of associated
* symbol table. And ->sh_info contains section header
* index of section to which relocations apply.
*/
if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
sechdrs[i].sh_link >= pi->ehdr->e_shnum)
return -ENOEXEC;
section = &sechdrs[sechdrs[i].sh_info];
symtab = &sechdrs[sechdrs[i].sh_link];
if (!(section->sh_flags & SHF_ALLOC))
continue;
/*
* symtab->sh_link contain section header index of associated
* string table.
*/
if (symtab->sh_link >= pi->ehdr->e_shnum)
/* Invalid section number? */
continue;
/*
* Respective architecture needs to provide support for applying
* relocations of type SHT_RELA/SHT_REL.
*/
if (sechdrs[i].sh_type == SHT_RELA)
ret = arch_kexec_apply_relocations_add(pi->ehdr,
sechdrs, i);
else if (sechdrs[i].sh_type == SHT_REL)
ret = arch_kexec_apply_relocations(pi->ehdr,
sechdrs, i);
if (ret)
return ret;
}
return 0;
}
/* Load relocatable purgatory object and relocate it appropriately */
int kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down,
unsigned long *load_addr)
{
struct purgatory_info *pi = &image->purgatory_info;
int ret;
if (kexec_purgatory_size <= 0)
return -EINVAL;
if (kexec_purgatory_size < sizeof(Elf_Ehdr))
return -ENOEXEC;
pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
|| pi->ehdr->e_type != ET_REL
|| !elf_check_arch(pi->ehdr)
|| pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
return -ENOEXEC;
if (pi->ehdr->e_shoff >= kexec_purgatory_size
|| (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
kexec_purgatory_size - pi->ehdr->e_shoff))
return -ENOEXEC;
ret = __kexec_load_purgatory(image, min, max, top_down);
if (ret)
return ret;
ret = kexec_apply_relocations(image);
if (ret)
goto out;
*load_addr = pi->purgatory_load_addr;
return 0;
out:
vfree(pi->sechdrs);
vfree(pi->purgatory_buf);
return ret;
}
static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
const char *name)
{
Elf_Sym *syms;
Elf_Shdr *sechdrs;
Elf_Ehdr *ehdr;
int i, k;
const char *strtab;
if (!pi->sechdrs || !pi->ehdr)
return NULL;
sechdrs = pi->sechdrs;
ehdr = pi->ehdr;
for (i = 0; i < ehdr->e_shnum; i++) {
if (sechdrs[i].sh_type != SHT_SYMTAB)
continue;
if (sechdrs[i].sh_link >= ehdr->e_shnum)
/* Invalid strtab section number */
continue;
strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
syms = (Elf_Sym *)sechdrs[i].sh_offset;
/* Go through symbols for a match */
for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
continue;
if (strcmp(strtab + syms[k].st_name, name) != 0)
continue;
if (syms[k].st_shndx == SHN_UNDEF ||
syms[k].st_shndx >= ehdr->e_shnum) {
pr_debug("Symbol: %s has bad section index %d.\n",
name, syms[k].st_shndx);
return NULL;
}
/* Found the symbol we are looking for */
return &syms[k];
}
}
return NULL;
}
void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
{
struct purgatory_info *pi = &image->purgatory_info;
Elf_Sym *sym;
Elf_Shdr *sechdr;
sym = kexec_purgatory_find_symbol(pi, name);
if (!sym)
return ERR_PTR(-EINVAL);
sechdr = &pi->sechdrs[sym->st_shndx];
/*
* Returns the address where symbol will finally be loaded after
* kexec_load_segment()
*/
return (void *)(sechdr->sh_addr + sym->st_value);
}
/*
* Get or set value of a symbol. If "get_value" is true, symbol value is
* returned in buf otherwise symbol value is set based on value in buf.
*/
int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
void *buf, unsigned int size, bool get_value)
{
Elf_Sym *sym;
Elf_Shdr *sechdrs;
struct purgatory_info *pi = &image->purgatory_info;
char *sym_buf;
sym = kexec_purgatory_find_symbol(pi, name);
if (!sym)
return -EINVAL;
if (sym->st_size != size) {
pr_err("symbol %s size mismatch: expected %lu actual %u\n",
name, (unsigned long)sym->st_size, size);
return -EINVAL;
}
sechdrs = pi->sechdrs;
if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
pr_err("symbol %s is in a bss section. Cannot %s\n", name,
get_value ? "get" : "set");
return -EINVAL;
}
sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
sym->st_value;
if (get_value)
memcpy((void *)buf, sym_buf, size);
else
memcpy((void *)sym_buf, buf, size);
return 0;
}