Quelle kexec_file.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
* kexec: kexec_file_load system call
*
* Copyright (C) 2014 Red Hat Inc.
* Authors:
*      Vivek Goyal <vgoyal@redhat.com>
*/

#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/memblock.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/ima.h>
#include <crypto/sha2.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/kernel.h>
#include <linux/kernel_read_file.h>
#include <linux/syscalls.h>
#include <linux/vmalloc.h>
#include <linux/dma-map-ops.h>
#include "kexec_internal.h"

#ifdef CONFIG_KEXEC_SIG
static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);

void set_kexec_sig_enforced(void)
{
sig_enforce = true;
}
#endif

#ifdef CONFIG_IMA_KEXEC
static bool check_ima_segment_index(struct kimage *image, int i)
{
if (image->is_ima_segment_index_set && i == image->ima_segment_index)
  return true;
else
  return false;
}
#else
static bool check_ima_segment_index(struct kimage *image, int i)
{
return false;
}
#endif

static int kexec_calculate_store_digests(struct kimage *image);

/* Maximum size in bytes for kernel/initrd files. */
#define KEXEC_FILE_SIZE_MAX min_t(s64, 4LL << 30, SSIZE_MAX)

/*
* Currently this is the only default function that is exported as some
* architectures need it to do additional handlings.
* In the future, other default functions may be exported too if required.
*/
int kexec_image_probe_default(struct kimage *image, void *buf,
         unsigned long buf_len)
{
const struct kexec_file_ops * const *fops;
int ret = -ENOEXEC;

for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
  ret = (*fops)->probe(buf, buf_len);
  if (!ret) {
   image->fops = *fops;
   return ret;
  }
}

return ret;
}

static void *kexec_image_load_default(struct kimage *image)
{
if (!image->fops || !image->fops->load)
  return ERR_PTR(-ENOEXEC);

return image->fops->load(image, image->kernel_buf,
     image->kernel_buf_len, image->initrd_buf,
     image->initrd_buf_len, image->cmdline_buf,
     image->cmdline_buf_len);
}

int kexec_image_post_load_cleanup_default(struct kimage *image)
{
if (!image->fops || !image->fops->cleanup)
  return 0;

return image->fops->cleanup(image->image_loader_data);
}

/*
* 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;

#ifdef CONFIG_IMA_KEXEC
vfree(image->ima_buffer);
image->ima_buffer = NULL;
#endif /* CONFIG_IMA_KEXEC */

/* 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;

kexec_file_dbg_print = false;
}

#ifdef CONFIG_KEXEC_SIG
#ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
{
int ret;

ret = verify_pefile_signature(kernel, kernel_len,
          VERIFY_USE_SECONDARY_KEYRING,
          VERIFYING_KEXEC_PE_SIGNATURE);
if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
  ret = verify_pefile_signature(kernel, kernel_len,
           VERIFY_USE_PLATFORM_KEYRING,
           VERIFYING_KEXEC_PE_SIGNATURE);
}
return ret;
}
#endif

static int kexec_image_verify_sig(struct kimage *image, void *buf,
      unsigned long buf_len)
{
if (!image->fops || !image->fops->verify_sig) {
  pr_debug("kernel loader does not support signature verification.\n");
  return -EKEYREJECTED;
}

return image->fops->verify_sig(buf, buf_len);
}

static int
kimage_validate_signature(struct kimage *image)
{
int ret;

ret = kexec_image_verify_sig(image, image->kernel_buf,
         image->kernel_buf_len);
if (ret) {

  if (sig_enforce) {
   pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
   return ret;
  }

  /*
* If IMA is guaranteed to appraise a signature on the kexec
* image, permit it even if the kernel is otherwise locked
* down.
*/
  if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
      security_locked_down(LOCKDOWN_KEXEC))
   return -EPERM;

  pr_debug("kernel signature verification failed (%d).\n", ret);
}

return 0;
}
#endif

static int kexec_post_load(struct kimage *image, unsigned long flags)
{
#ifdef CONFIG_IMA_KEXEC
if (!(flags & KEXEC_FILE_ON_CRASH))
  ima_kexec_post_load(image);
#endif
return machine_kexec_post_load(image);
}

/*
* 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)
{
ssize_t ret;
void *ldata;

ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
           KEXEC_FILE_SIZE_MAX, NULL,
           READING_KEXEC_IMAGE);
if (ret < 0)
  return ret;
image->kernel_buf_len = ret;
kexec_dprintk("kernel: %p kernel_size: %#lx\n",
        image->kernel_buf, image->kernel_buf_len);

/* 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_SIG
ret = kimage_validate_signature(image);

if (ret)
  goto out;
#endif
/* It is possible that there no initramfs is being loaded */
if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
  ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
            KEXEC_FILE_SIZE_MAX, NULL,
            READING_KEXEC_INITRAMFS);
  if (ret < 0)
   goto out;
  image->initrd_buf_len = ret;
  ret = 0;
}

image->no_cma = !!(flags & KEXEC_FILE_NO_CMA);

if (cmdline_len) {
  image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
  if (IS_ERR(image->cmdline_buf)) {
   ret = PTR_ERR(image->cmdline_buf);
   image->cmdline_buf = NULL;
   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;
  }

  ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
      image->cmdline_buf_len - 1);
}

/* IMA needs to pass the measurement list to the next kernel. */
ima_add_kexec_buffer(image);

/* If KHO is active, add its images to the list */
ret = kho_fill_kimage(image);
if (ret)
  goto out;

/* Call image load handler */
ldata = kexec_image_load_default(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;

kexec_file_dbg_print = !!(flags & KEXEC_FILE_DEBUG);
image->file_mode = 1;

#ifdef CONFIG_CRASH_DUMP
if (kexec_on_panic) {
  /* Enable special crash kernel control page alloc policy. */
  image->control_page = crashk_res.start;
  image->type = KEXEC_TYPE_CRASH;
}
#endif

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 image_type = (flags & KEXEC_FILE_ON_CRASH) ?
    KEXEC_TYPE_CRASH : KEXEC_TYPE_DEFAULT;
struct kimage **dest_image, *image;
int ret = 0, i;

/* We only trust the superuser with rebooting the system. */
if (!kexec_load_permitted(image_type))
  return -EPERM;

/* Make sure we have a legal set of flags */
if (flags != (flags & KEXEC_FILE_FLAGS))
  return -EINVAL;

image = NULL;

if (!kexec_trylock())
  return -EBUSY;

#ifdef CONFIG_CRASH_DUMP
if (image_type == KEXEC_TYPE_CRASH) {
  dest_image = &kexec_crash_image;
  if (kexec_crash_image)
   arch_kexec_unprotect_crashkres();
} else
#endif
  dest_image = &kexec_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;

#ifdef CONFIG_CRASH_HOTPLUG
if ((flags & KEXEC_FILE_ON_CRASH) && arch_crash_hotplug_support(image, flags))
  image->hotplug_support = 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;

ret = kexec_calculate_store_digests(image);
if (ret)
  goto out;

kexec_dprintk("nr_segments = %lu\n", image->nr_segments);
for (i = 0; i < image->nr_segments; i++) {
  struct kexec_segment *ksegment;

  ksegment = &image->segment[i];
  kexec_dprintk("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, i);
  if (ret)
   goto out;
}

kimage_terminate(image);

ret = kexec_post_load(image, flags);
if (ret)
  goto out;

kexec_dprintk("kexec_file_load: type:%u, start:0x%lx head:0x%lx flags:0x%lx\n",
        image->type, image->start, image->head, flags);
/*
* 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:
#ifdef CONFIG_CRASH_DUMP
if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
  arch_kexec_protect_crashkres();
#endif

kexec_unlock();
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 + 1;
kexec_random_range_start(temp_start, temp_end, kbuf, &temp_start);

do {
  /* align down start */
  temp_start = ALIGN_DOWN(temp_start, kbuf->buf_align);

  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;
  }

  /* Make sure this does not conflict with exclude range */
  if (arch_check_excluded_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);

kexec_random_range_start(temp_start, end, kbuf, &temp_start);

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;
  }

  /* Make sure this does not conflict with exclude range */
  if (arch_check_excluded_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(struct resource *res, void *arg)
{
struct kexec_buf *kbuf = (struct kexec_buf *)arg;
u64 start = res->start, end = res->end;
unsigned long sz = end - start + 1;

/* Returning 0 will take to next memory range */

/* Don't use memory that will be detected and handled by a driver. */
if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
  return 0;

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);
}

#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
static int kexec_walk_memblock(struct kexec_buf *kbuf,
          int (*func)(struct resource *, void *))
{
int ret = 0;
u64 i;
phys_addr_t mstart, mend;
struct resource res = { };

#ifdef CONFIG_CRASH_DUMP
if (kbuf->image->type == KEXEC_TYPE_CRASH)
  return func(&crashk_res, kbuf);
#endif

/*
* Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
* IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
* locate_mem_hole_callback().
*/
if (kbuf->top_down) {
  for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
      &mstart, &mend, NULL) {
   /*
* In memblock, end points to the first byte after the
* range while in kexec, end points to the last byte
* in the range.
*/
   res.start = mstart;
   res.end = mend - 1;
   ret = func(&res, kbuf);
   if (ret)
    break;
  }
} else {
  for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
     &mstart, &mend, NULL) {
   /*
* In memblock, end points to the first byte after the
* range while in kexec, end points to the last byte
* in the range.
*/
   res.start = mstart;
   res.end = mend - 1;
   ret = func(&res, kbuf);
   if (ret)
    break;
  }
}

return ret;
}
#else
static int kexec_walk_memblock(struct kexec_buf *kbuf,
          int (*func)(struct resource *, void *))
{
return 0;
}
#endif

/**
* kexec_walk_resources - call func(data) on free memory regions
* @kbuf: Context info for the search. Also passed to @func.
* @func: Function to call for each memory region.
*
* Return: The memory walk will stop when func returns a non-zero value
* and that value will be returned. If all free regions are visited without
* func returning non-zero, then zero will be returned.
*/
static int kexec_walk_resources(struct kexec_buf *kbuf,
    int (*func)(struct resource *, void *))
{
#ifdef CONFIG_CRASH_DUMP
if (kbuf->image->type == KEXEC_TYPE_CRASH)
  return walk_iomem_res_desc(crashk_res.desc,
        IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
        crashk_res.start, crashk_res.end,
        kbuf, func);
#endif
if (kbuf->top_down)
  return walk_system_ram_res_rev(0, ULONG_MAX, kbuf, func);
else
  return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
}

static int kexec_alloc_contig(struct kexec_buf *kbuf)
{
size_t nr_pages = kbuf->memsz >> PAGE_SHIFT;
unsigned long mem;
struct page *p;

/* User space disabled CMA allocations, bail out. */
if (kbuf->image->no_cma)
  return -EPERM;

/* Skip CMA logic for crash kernel */
if (kbuf->image->type == KEXEC_TYPE_CRASH)
  return -EPERM;

p = dma_alloc_from_contiguous(NULL, nr_pages, get_order(kbuf->buf_align), true);
if (!p)
  return -ENOMEM;

pr_debug("allocated %zu DMA pages at 0x%lx", nr_pages, page_to_boot_pfn(p));

mem = page_to_boot_pfn(p) << PAGE_SHIFT;

if (kimage_is_destination_range(kbuf->image, mem, mem + kbuf->memsz)) {
  /* Our region is already in use by a statically defined one. Bail out. */
  pr_debug("CMA overlaps existing mem: 0x%lx+0x%lx\n", mem, kbuf->memsz);
  dma_release_from_contiguous(NULL, p, nr_pages);
  return -EBUSY;
}

kbuf->mem = page_to_boot_pfn(p) << PAGE_SHIFT;
kbuf->cma = p;

arch_kexec_post_alloc_pages(page_address(p), (int)nr_pages, 0);

return 0;
}

/**
* kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
* @kbuf: Parameters for the memory search.
*
* On success, kbuf->mem will have the start address of the memory region found.
*
* Return: 0 on success, negative errno on error.
*/
int kexec_locate_mem_hole(struct kexec_buf *kbuf)
{
int ret;

/* Arch knows where to place */
if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
  return 0;

/*
* If KHO is active, only use KHO scratch memory. All other memory
* could potentially be handed over.
*/
ret = kho_locate_mem_hole(kbuf, locate_mem_hole_callback);
if (ret <= 0)
  return ret;

/*
* Try to find a free physically contiguous block of memory first. With that, we
* can avoid any copying at kexec time.
*/
if (!kexec_alloc_contig(kbuf))
  return 0;

if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
  ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
else
  ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);

return ret == 1 ? 0 : -EADDRNOTAVAIL;
}

/**
* kexec_add_buffer - place a buffer in a kexec segment
* @kbuf: Buffer contents and memory parameters.
*
* This function assumes that kexec_lock is held.
* On successful return, @kbuf->mem will have the physical address of
* the buffer in memory.
*
* Return: 0 on success, negative errno on error.
*/
int kexec_add_buffer(struct kexec_buf *kbuf)
{
struct kexec_segment *ksegment;
int ret;

/* Currently adding segment this way is allowed only in file mode */
if (!kbuf->image->file_mode)
  return -EINVAL;

if (kbuf->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(&kbuf->image->control_pages)) {
  WARN_ON(1);
  return -EINVAL;
}

/* Ensure minimum alignment needed for segments. */
kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
kbuf->cma = NULL;

/* Walk the RAM ranges and allocate a suitable range for the buffer */
ret = arch_kexec_locate_mem_hole(kbuf);
if (ret)
  return ret;

/* Found a suitable memory range */
ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
ksegment->kbuf = kbuf->buffer;
ksegment->bufsz = kbuf->bufsz;
ksegment->mem = kbuf->mem;
ksegment->memsz = kbuf->memsz;
kbuf->image->segment_cma[kbuf->image->nr_segments] = kbuf->cma;
kbuf->image->nr_segments++;
return 0;
}

/* Calculate and store the digest of segments */
static int kexec_calculate_store_digests(struct kimage *image)
{
struct sha256_ctx sctx;
int ret = 0, i, j, zero_buf_sz, sha_region_sz;
size_t nullsz;
u8 digest[SHA256_DIGEST_SIZE];
void *zero_buf;
struct kexec_sha_region *sha_regions;
struct purgatory_info *pi = &image->purgatory_info;

if (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY))
  return 0;

zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
zero_buf_sz = PAGE_SIZE;

sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
sha_regions = vzalloc(sha_region_sz);
if (!sha_regions)
  return -ENOMEM;

sha256_init(&sctx);

for (j = i = 0; i < image->nr_segments; i++) {
  struct kexec_segment *ksegment;

#ifdef CONFIG_CRASH_HOTPLUG
  /* Exclude elfcorehdr segment to allow future changes via hotplug */
  if (i == image->elfcorehdr_index)
   continue;
#endif

  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;

  /*
* Skip the segment if ima_segment_index is set and matches
* the current index
*/
  if (check_ima_segment_index(image, i))
   continue;

  sha256_update(&sctx, ksegment->kbuf, ksegment->bufsz);

  /*
* 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;
   sha256_update(&sctx, zero_buf, bytes);
   nullsz -= bytes;
  }

  sha_regions[j].start = ksegment->mem;
  sha_regions[j].len = ksegment->memsz;
  j++;
}

sha256_final(&sctx, digest);

ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
          sha_regions, sha_region_sz, 0);
if (ret)
  goto out_free_sha_regions;

ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
          digest, SHA256_DIGEST_SIZE, 0);
out_free_sha_regions:
vfree(sha_regions);
return ret;
}

#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
/*
* kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
* @pi: Purgatory to be loaded.
* @kbuf: Buffer to setup.
*
* Allocates the memory needed for the buffer. Caller is responsible to free
* the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
          struct kexec_buf *kbuf)
{
const Elf_Shdr *sechdrs;
unsigned long bss_align;
unsigned long bss_sz;
unsigned long align;
int i, ret;

sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
kbuf->buf_align = bss_align = 1;
kbuf->bufsz = 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 (kbuf->buf_align < align)
    kbuf->buf_align = align;
   kbuf->bufsz = ALIGN(kbuf->bufsz, align);
   kbuf->bufsz += sechdrs[i].sh_size;
  } else {
   if (bss_align < align)
    bss_align = align;
   bss_sz = ALIGN(bss_sz, align);
   bss_sz += sechdrs[i].sh_size;
  }
}
kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
kbuf->memsz = kbuf->bufsz + bss_sz;
if (kbuf->buf_align < bss_align)
  kbuf->buf_align = bss_align;

kbuf->buffer = vzalloc(kbuf->bufsz);
if (!kbuf->buffer)
  return -ENOMEM;
pi->purgatory_buf = kbuf->buffer;

ret = kexec_add_buffer(kbuf);
if (ret)
  goto out;

return 0;
out:
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
return ret;
}

/*
* kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
* @pi: Purgatory to be loaded.
* @kbuf: Buffer prepared to store purgatory.
*
* Allocates the memory needed for the buffer. Caller is responsible to free
* the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
      struct kexec_buf *kbuf)
{
unsigned long bss_addr;
unsigned long offset;
size_t sechdrs_size;
Elf_Shdr *sechdrs;
int i;

/*
* The section headers in kexec_purgatory are read-only. In order to
* have them modifiable make a temporary copy.
*/
sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
sechdrs = vzalloc(sechdrs_size);
if (!sechdrs)
  return -ENOMEM;
memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
pi->sechdrs = sechdrs;

offset = 0;
bss_addr = kbuf->mem + kbuf->bufsz;
kbuf->image->start = pi->ehdr->e_entry;

for (i = 0; i < pi->ehdr->e_shnum; i++) {
  unsigned long align;
  void *src, *dst;

  if (!(sechdrs[i].sh_flags & SHF_ALLOC))
   continue;

  align = sechdrs[i].sh_addralign;
  if (sechdrs[i].sh_type == SHT_NOBITS) {
   bss_addr = ALIGN(bss_addr, align);
   sechdrs[i].sh_addr = bss_addr;
   bss_addr += sechdrs[i].sh_size;
   continue;
  }

  offset = ALIGN(offset, align);

  /*
* Check if the segment contains the entry point, if so,
* calculate the value of image->start based on it.
* If the compiler has produced more than one .text section
* (Eg: .text.hot), they are generally after the main .text
* section, and they shall not be used to calculate
* image->start. So do not re-calculate image->start if it
* is not set to the initial value, and warn the user so they
* have a chance to fix their purgatory's linker script.
*/
  if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
      pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
      pi->ehdr->e_entry < (sechdrs[i].sh_addr
      + sechdrs[i].sh_size) &&
      !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) {
   kbuf->image->start -= sechdrs[i].sh_addr;
   kbuf->image->start += kbuf->mem + offset;
  }

  src = (void *)pi->ehdr + sechdrs[i].sh_offset;
  dst = pi->purgatory_buf + offset;
  memcpy(dst, src, sechdrs[i].sh_size);

  sechdrs[i].sh_addr = kbuf->mem + offset;
  sechdrs[i].sh_offset = offset;
  offset += sechdrs[i].sh_size;
}

return 0;
}

static int kexec_apply_relocations(struct kimage *image)
{
int i, ret;
struct purgatory_info *pi = &image->purgatory_info;
const Elf_Shdr *sechdrs;

sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;

for (i = 0; i < pi->ehdr->e_shnum; i++) {
  const Elf_Shdr *relsec;
  const Elf_Shdr *symtab;
  Elf_Shdr *section;

  relsec = sechdrs + i;

  if (relsec->sh_type != SHT_RELA &&
      relsec->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 (relsec->sh_info >= pi->ehdr->e_shnum ||
      relsec->sh_link >= pi->ehdr->e_shnum)
   return -ENOEXEC;

  section = pi->sechdrs + relsec->sh_info;
  symtab = sechdrs + relsec->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 (relsec->sh_type == SHT_RELA)
   ret = arch_kexec_apply_relocations_add(pi, section,
              relsec, symtab);
  else if (relsec->sh_type == SHT_REL)
   ret = arch_kexec_apply_relocations(pi, section,
          relsec, symtab);
  if (ret)
   return ret;
}

return 0;
}

/*
* kexec_load_purgatory - Load and relocate the purgatory object.
* @image: Image to add the purgatory to.
* @kbuf: Memory parameters to use.
*
* Allocates the memory needed for image->purgatory_info.sechdrs and
* image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
* to free the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
{
struct purgatory_info *pi = &image->purgatory_info;
int ret;

if (kexec_purgatory_size <= 0)
  return -EINVAL;

pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;

ret = kexec_purgatory_setup_kbuf(pi, kbuf);
if (ret)
  return ret;

ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
if (ret)
  goto out_free_kbuf;

ret = kexec_apply_relocations(image);
if (ret)
  goto out;

return 0;
out:
vfree(pi->sechdrs);
pi->sechdrs = NULL;
out_free_kbuf:
vfree(pi->purgatory_buf);
pi->purgatory_buf = NULL;
return ret;
}

/*
* kexec_purgatory_find_symbol - find a symbol in the purgatory
* @pi: Purgatory to search in.
* @name: Name of the symbol.
*
* Return: pointer to symbol in read-only symtab on success, NULL on error.
*/
static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
        const char *name)
{
const Elf_Shdr *sechdrs;
const Elf_Ehdr *ehdr;
const Elf_Sym *syms;
const char *strtab;
int i, k;

if (!pi->ehdr)
  return NULL;

ehdr = pi->ehdr;
sechdrs = (void *)ehdr + ehdr->e_shoff;

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 = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
  syms = (void *)ehdr + 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;
const 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)
{
struct purgatory_info *pi = &image->purgatory_info;
const Elf_Sym *sym;
Elf_Shdr *sec;
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;
}

sec = pi->sechdrs + sym->st_shndx;

if (sec->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 = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;

if (get_value)
  memcpy((void *)buf, sym_buf, size);
else
  memcpy((void *)sym_buf, buf, size);

return 0;
}
#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */

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