linux/fs/proc/vmcore.c
WANG Chao 34b4776429 vmcore: fix PT_NOTE n_namesz, n_descsz overflow issue
When updating PT_NOTE header size (ie.  p_memsz), an overflow issue
happens with the following bogus note entry:

  n_namesz = 0xFFFFFFFF
  n_descsz = 0x0
  n_type   = 0x0

This kind of note entry should be dropped during updating p_memsz.  But
because n_namesz is 32bit, after (n_namesz + 3) & (~3), it's overflow to
0x0, the note entry size looks sane and reserved.

When userspace (eg.  crash utility) is trying to access such bogus note,
it could lead to an unexpected behavior (eg.  crash utility segment fault
because it's reading bogus address).

The source of bogus note hasn't been identified yet.  At least we could
drop the bogus note so user space wouldn't be surprised.

Signed-off-by: WANG Chao <chaowang@redhat.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Randy Wright <rwright@hp.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Rashika Kheria <rashika.kheria@gmail.com>
Cc: Greg Pearson <greg.pearson@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-17 14:34:52 -08:00

1195 lines
30 KiB
C

/*
* fs/proc/vmcore.c Interface for accessing the crash
* dump from the system's previous life.
* Heavily borrowed from fs/proc/kcore.c
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
* Copyright (C) IBM Corporation, 2004. All rights reserved
*
*/
#include <linux/mm.h>
#include <linux/kcore.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/printk.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/crash_dump.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include "internal.h"
/* List representing chunks of contiguous memory areas and their offsets in
* vmcore file.
*/
static LIST_HEAD(vmcore_list);
/* Stores the pointer to the buffer containing kernel elf core headers. */
static char *elfcorebuf;
static size_t elfcorebuf_sz;
static size_t elfcorebuf_sz_orig;
static char *elfnotes_buf;
static size_t elfnotes_sz;
/* Total size of vmcore file. */
static u64 vmcore_size;
static struct proc_dir_entry *proc_vmcore;
/*
* Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
* The called function has to take care of module refcounting.
*/
static int (*oldmem_pfn_is_ram)(unsigned long pfn);
int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
{
if (oldmem_pfn_is_ram)
return -EBUSY;
oldmem_pfn_is_ram = fn;
return 0;
}
EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
void unregister_oldmem_pfn_is_ram(void)
{
oldmem_pfn_is_ram = NULL;
wmb();
}
EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
static int pfn_is_ram(unsigned long pfn)
{
int (*fn)(unsigned long pfn);
/* pfn is ram unless fn() checks pagetype */
int ret = 1;
/*
* Ask hypervisor if the pfn is really ram.
* A ballooned page contains no data and reading from such a page
* will cause high load in the hypervisor.
*/
fn = oldmem_pfn_is_ram;
if (fn)
ret = fn(pfn);
return ret;
}
/* Reads a page from the oldmem device from given offset. */
static ssize_t read_from_oldmem(char *buf, size_t count,
u64 *ppos, int userbuf)
{
unsigned long pfn, offset;
size_t nr_bytes;
ssize_t read = 0, tmp;
if (!count)
return 0;
offset = (unsigned long)(*ppos % PAGE_SIZE);
pfn = (unsigned long)(*ppos / PAGE_SIZE);
do {
if (count > (PAGE_SIZE - offset))
nr_bytes = PAGE_SIZE - offset;
else
nr_bytes = count;
/* If pfn is not ram, return zeros for sparse dump files */
if (pfn_is_ram(pfn) == 0)
memset(buf, 0, nr_bytes);
else {
tmp = copy_oldmem_page(pfn, buf, nr_bytes,
offset, userbuf);
if (tmp < 0)
return tmp;
}
*ppos += nr_bytes;
count -= nr_bytes;
buf += nr_bytes;
read += nr_bytes;
++pfn;
offset = 0;
} while (count);
return read;
}
/*
* Architectures may override this function to allocate ELF header in 2nd kernel
*/
int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
{
return 0;
}
/*
* Architectures may override this function to free header
*/
void __weak elfcorehdr_free(unsigned long long addr)
{}
/*
* Architectures may override this function to read from ELF header
*/
ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
return read_from_oldmem(buf, count, ppos, 0);
}
/*
* Architectures may override this function to read from notes sections
*/
ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
{
return read_from_oldmem(buf, count, ppos, 0);
}
/*
* Architectures may override this function to map oldmem
*/
int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
unsigned long from, unsigned long pfn,
unsigned long size, pgprot_t prot)
{
return remap_pfn_range(vma, from, pfn, size, prot);
}
/*
* Copy to either kernel or user space
*/
static int copy_to(void *target, void *src, size_t size, int userbuf)
{
if (userbuf) {
if (copy_to_user((char __user *) target, src, size))
return -EFAULT;
} else {
memcpy(target, src, size);
}
return 0;
}
/* Read from the ELF header and then the crash dump. On error, negative value is
* returned otherwise number of bytes read are returned.
*/
static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
int userbuf)
{
ssize_t acc = 0, tmp;
size_t tsz;
u64 start;
struct vmcore *m = NULL;
if (buflen == 0 || *fpos >= vmcore_size)
return 0;
/* trim buflen to not go beyond EOF */
if (buflen > vmcore_size - *fpos)
buflen = vmcore_size - *fpos;
/* Read ELF core header */
if (*fpos < elfcorebuf_sz) {
tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);
if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))
return -EFAULT;
buflen -= tsz;
*fpos += tsz;
buffer += tsz;
acc += tsz;
/* leave now if filled buffer already */
if (buflen == 0)
return acc;
}
/* Read Elf note segment */
if (*fpos < elfcorebuf_sz + elfnotes_sz) {
void *kaddr;
tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);
kaddr = elfnotes_buf + *fpos - elfcorebuf_sz;
if (copy_to(buffer, kaddr, tsz, userbuf))
return -EFAULT;
buflen -= tsz;
*fpos += tsz;
buffer += tsz;
acc += tsz;
/* leave now if filled buffer already */
if (buflen == 0)
return acc;
}
list_for_each_entry(m, &vmcore_list, list) {
if (*fpos < m->offset + m->size) {
tsz = min_t(size_t, m->offset + m->size - *fpos, buflen);
start = m->paddr + *fpos - m->offset;
tmp = read_from_oldmem(buffer, tsz, &start, userbuf);
if (tmp < 0)
return tmp;
buflen -= tsz;
*fpos += tsz;
buffer += tsz;
acc += tsz;
/* leave now if filled buffer already */
if (buflen == 0)
return acc;
}
}
return acc;
}
static ssize_t read_vmcore(struct file *file, char __user *buffer,
size_t buflen, loff_t *fpos)
{
return __read_vmcore((__force char *) buffer, buflen, fpos, 1);
}
/*
* The vmcore fault handler uses the page cache and fills data using the
* standard __vmcore_read() function.
*
* On s390 the fault handler is used for memory regions that can't be mapped
* directly with remap_pfn_range().
*/
static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
#ifdef CONFIG_S390
struct address_space *mapping = vma->vm_file->f_mapping;
pgoff_t index = vmf->pgoff;
struct page *page;
loff_t offset;
char *buf;
int rc;
page = find_or_create_page(mapping, index, GFP_KERNEL);
if (!page)
return VM_FAULT_OOM;
if (!PageUptodate(page)) {
offset = (loff_t) index << PAGE_CACHE_SHIFT;
buf = __va((page_to_pfn(page) << PAGE_SHIFT));
rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);
if (rc < 0) {
unlock_page(page);
page_cache_release(page);
return (rc == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
}
SetPageUptodate(page);
}
unlock_page(page);
vmf->page = page;
return 0;
#else
return VM_FAULT_SIGBUS;
#endif
}
static const struct vm_operations_struct vmcore_mmap_ops = {
.fault = mmap_vmcore_fault,
};
/**
* alloc_elfnotes_buf - allocate buffer for ELF note segment in
* vmalloc memory
*
* @notes_sz: size of buffer
*
* If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
* the buffer to user-space by means of remap_vmalloc_range().
*
* If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
* disabled and there's no need to allow users to mmap the buffer.
*/
static inline char *alloc_elfnotes_buf(size_t notes_sz)
{
#ifdef CONFIG_MMU
return vmalloc_user(notes_sz);
#else
return vzalloc(notes_sz);
#endif
}
/*
* Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
* essential for mmap_vmcore() in order to map physically
* non-contiguous objects (ELF header, ELF note segment and memory
* regions in the 1st kernel pointed to by PT_LOAD entries) into
* virtually contiguous user-space in ELF layout.
*/
#ifdef CONFIG_MMU
/*
* remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
* reported as not being ram with the zero page.
*
* @vma: vm_area_struct describing requested mapping
* @from: start remapping from
* @pfn: page frame number to start remapping to
* @size: remapping size
* @prot: protection bits
*
* Returns zero on success, -EAGAIN on failure.
*/
static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
unsigned long from, unsigned long pfn,
unsigned long size, pgprot_t prot)
{
unsigned long map_size;
unsigned long pos_start, pos_end, pos;
unsigned long zeropage_pfn = my_zero_pfn(0);
size_t len = 0;
pos_start = pfn;
pos_end = pfn + (size >> PAGE_SHIFT);
for (pos = pos_start; pos < pos_end; ++pos) {
if (!pfn_is_ram(pos)) {
/*
* We hit a page which is not ram. Remap the continuous
* region between pos_start and pos-1 and replace
* the non-ram page at pos with the zero page.
*/
if (pos > pos_start) {
/* Remap continuous region */
map_size = (pos - pos_start) << PAGE_SHIFT;
if (remap_oldmem_pfn_range(vma, from + len,
pos_start, map_size,
prot))
goto fail;
len += map_size;
}
/* Remap the zero page */
if (remap_oldmem_pfn_range(vma, from + len,
zeropage_pfn,
PAGE_SIZE, prot))
goto fail;
len += PAGE_SIZE;
pos_start = pos + 1;
}
}
if (pos > pos_start) {
/* Remap the rest */
map_size = (pos - pos_start) << PAGE_SHIFT;
if (remap_oldmem_pfn_range(vma, from + len, pos_start,
map_size, prot))
goto fail;
}
return 0;
fail:
do_munmap(vma->vm_mm, from, len);
return -EAGAIN;
}
static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
unsigned long from, unsigned long pfn,
unsigned long size, pgprot_t prot)
{
/*
* Check if oldmem_pfn_is_ram was registered to avoid
* looping over all pages without a reason.
*/
if (oldmem_pfn_is_ram)
return remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
else
return remap_oldmem_pfn_range(vma, from, pfn, size, prot);
}
static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
{
size_t size = vma->vm_end - vma->vm_start;
u64 start, end, len, tsz;
struct vmcore *m;
start = (u64)vma->vm_pgoff << PAGE_SHIFT;
end = start + size;
if (size > vmcore_size || end > vmcore_size)
return -EINVAL;
if (vma->vm_flags & (VM_WRITE | VM_EXEC))
return -EPERM;
vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
vma->vm_flags |= VM_MIXEDMAP;
vma->vm_ops = &vmcore_mmap_ops;
len = 0;
if (start < elfcorebuf_sz) {
u64 pfn;
tsz = min(elfcorebuf_sz - (size_t)start, size);
pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
vma->vm_page_prot))
return -EAGAIN;
size -= tsz;
start += tsz;
len += tsz;
if (size == 0)
return 0;
}
if (start < elfcorebuf_sz + elfnotes_sz) {
void *kaddr;
tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
kaddr = elfnotes_buf + start - elfcorebuf_sz;
if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
kaddr, tsz))
goto fail;
size -= tsz;
start += tsz;
len += tsz;
if (size == 0)
return 0;
}
list_for_each_entry(m, &vmcore_list, list) {
if (start < m->offset + m->size) {
u64 paddr = 0;
tsz = min_t(size_t, m->offset + m->size - start, size);
paddr = m->paddr + start - m->offset;
if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len,
paddr >> PAGE_SHIFT, tsz,
vma->vm_page_prot))
goto fail;
size -= tsz;
start += tsz;
len += tsz;
if (size == 0)
return 0;
}
}
return 0;
fail:
do_munmap(vma->vm_mm, vma->vm_start, len);
return -EAGAIN;
}
#else
static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
{
return -ENOSYS;
}
#endif
static const struct file_operations proc_vmcore_operations = {
.read = read_vmcore,
.llseek = default_llseek,
.mmap = mmap_vmcore,
};
static struct vmcore* __init get_new_element(void)
{
return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
}
static u64 __init get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
struct list_head *vc_list)
{
u64 size;
struct vmcore *m;
size = elfsz + elfnotesegsz;
list_for_each_entry(m, vc_list, list) {
size += m->size;
}
return size;
}
/**
* update_note_header_size_elf64 - update p_memsz member of each PT_NOTE entry
*
* @ehdr_ptr: ELF header
*
* This function updates p_memsz member of each PT_NOTE entry in the
* program header table pointed to by @ehdr_ptr to real size of ELF
* note segment.
*/
static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
{
int i, rc=0;
Elf64_Phdr *phdr_ptr;
Elf64_Nhdr *nhdr_ptr;
phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
void *notes_section;
u64 offset, max_sz, sz, real_sz = 0;
if (phdr_ptr->p_type != PT_NOTE)
continue;
max_sz = phdr_ptr->p_memsz;
offset = phdr_ptr->p_offset;
notes_section = kmalloc(max_sz, GFP_KERNEL);
if (!notes_section)
return -ENOMEM;
rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
if (rc < 0) {
kfree(notes_section);
return rc;
}
nhdr_ptr = notes_section;
while (nhdr_ptr->n_namesz != 0) {
sz = sizeof(Elf64_Nhdr) +
(((u64)nhdr_ptr->n_namesz + 3) & ~3) +
(((u64)nhdr_ptr->n_descsz + 3) & ~3);
if ((real_sz + sz) > max_sz) {
pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
break;
}
real_sz += sz;
nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
}
kfree(notes_section);
phdr_ptr->p_memsz = real_sz;
if (real_sz == 0) {
pr_warn("Warning: Zero PT_NOTE entries found\n");
}
}
return 0;
}
/**
* get_note_number_and_size_elf64 - get the number of PT_NOTE program
* headers and sum of real size of their ELF note segment headers and
* data.
*
* @ehdr_ptr: ELF header
* @nr_ptnote: buffer for the number of PT_NOTE program headers
* @sz_ptnote: buffer for size of unique PT_NOTE program header
*
* This function is used to merge multiple PT_NOTE program headers
* into a unique single one. The resulting unique entry will have
* @sz_ptnote in its phdr->p_mem.
*
* It is assumed that program headers with PT_NOTE type pointed to by
* @ehdr_ptr has already been updated by update_note_header_size_elf64
* and each of PT_NOTE program headers has actual ELF note segment
* size in its p_memsz member.
*/
static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
int *nr_ptnote, u64 *sz_ptnote)
{
int i;
Elf64_Phdr *phdr_ptr;
*nr_ptnote = *sz_ptnote = 0;
phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
if (phdr_ptr->p_type != PT_NOTE)
continue;
*nr_ptnote += 1;
*sz_ptnote += phdr_ptr->p_memsz;
}
return 0;
}
/**
* copy_notes_elf64 - copy ELF note segments in a given buffer
*
* @ehdr_ptr: ELF header
* @notes_buf: buffer into which ELF note segments are copied
*
* This function is used to copy ELF note segment in the 1st kernel
* into the buffer @notes_buf in the 2nd kernel. It is assumed that
* size of the buffer @notes_buf is equal to or larger than sum of the
* real ELF note segment headers and data.
*
* It is assumed that program headers with PT_NOTE type pointed to by
* @ehdr_ptr has already been updated by update_note_header_size_elf64
* and each of PT_NOTE program headers has actual ELF note segment
* size in its p_memsz member.
*/
static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
{
int i, rc=0;
Elf64_Phdr *phdr_ptr;
phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
u64 offset;
if (phdr_ptr->p_type != PT_NOTE)
continue;
offset = phdr_ptr->p_offset;
rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
&offset);
if (rc < 0)
return rc;
notes_buf += phdr_ptr->p_memsz;
}
return 0;
}
/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
char **notes_buf, size_t *notes_sz)
{
int i, nr_ptnote=0, rc=0;
char *tmp;
Elf64_Ehdr *ehdr_ptr;
Elf64_Phdr phdr;
u64 phdr_sz = 0, note_off;
ehdr_ptr = (Elf64_Ehdr *)elfptr;
rc = update_note_header_size_elf64(ehdr_ptr);
if (rc < 0)
return rc;
rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
if (rc < 0)
return rc;
*notes_sz = roundup(phdr_sz, PAGE_SIZE);
*notes_buf = alloc_elfnotes_buf(*notes_sz);
if (!*notes_buf)
return -ENOMEM;
rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
if (rc < 0)
return rc;
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
note_off = sizeof(Elf64_Ehdr) +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
phdr.p_offset = roundup(note_off, PAGE_SIZE);
phdr.p_vaddr = phdr.p_paddr = 0;
phdr.p_filesz = phdr.p_memsz = phdr_sz;
phdr.p_align = 0;
/* Add merged PT_NOTE program header*/
tmp = elfptr + sizeof(Elf64_Ehdr);
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);
/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
*elfsz = *elfsz - i;
memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
memset(elfptr + *elfsz, 0, i);
*elfsz = roundup(*elfsz, PAGE_SIZE);
/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
return 0;
}
/**
* update_note_header_size_elf32 - update p_memsz member of each PT_NOTE entry
*
* @ehdr_ptr: ELF header
*
* This function updates p_memsz member of each PT_NOTE entry in the
* program header table pointed to by @ehdr_ptr to real size of ELF
* note segment.
*/
static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
{
int i, rc=0;
Elf32_Phdr *phdr_ptr;
Elf32_Nhdr *nhdr_ptr;
phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
void *notes_section;
u64 offset, max_sz, sz, real_sz = 0;
if (phdr_ptr->p_type != PT_NOTE)
continue;
max_sz = phdr_ptr->p_memsz;
offset = phdr_ptr->p_offset;
notes_section = kmalloc(max_sz, GFP_KERNEL);
if (!notes_section)
return -ENOMEM;
rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
if (rc < 0) {
kfree(notes_section);
return rc;
}
nhdr_ptr = notes_section;
while (nhdr_ptr->n_namesz != 0) {
sz = sizeof(Elf32_Nhdr) +
(((u64)nhdr_ptr->n_namesz + 3) & ~3) +
(((u64)nhdr_ptr->n_descsz + 3) & ~3);
if ((real_sz + sz) > max_sz) {
pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
break;
}
real_sz += sz;
nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
}
kfree(notes_section);
phdr_ptr->p_memsz = real_sz;
if (real_sz == 0) {
pr_warn("Warning: Zero PT_NOTE entries found\n");
}
}
return 0;
}
/**
* get_note_number_and_size_elf32 - get the number of PT_NOTE program
* headers and sum of real size of their ELF note segment headers and
* data.
*
* @ehdr_ptr: ELF header
* @nr_ptnote: buffer for the number of PT_NOTE program headers
* @sz_ptnote: buffer for size of unique PT_NOTE program header
*
* This function is used to merge multiple PT_NOTE program headers
* into a unique single one. The resulting unique entry will have
* @sz_ptnote in its phdr->p_mem.
*
* It is assumed that program headers with PT_NOTE type pointed to by
* @ehdr_ptr has already been updated by update_note_header_size_elf32
* and each of PT_NOTE program headers has actual ELF note segment
* size in its p_memsz member.
*/
static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
int *nr_ptnote, u64 *sz_ptnote)
{
int i;
Elf32_Phdr *phdr_ptr;
*nr_ptnote = *sz_ptnote = 0;
phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
if (phdr_ptr->p_type != PT_NOTE)
continue;
*nr_ptnote += 1;
*sz_ptnote += phdr_ptr->p_memsz;
}
return 0;
}
/**
* copy_notes_elf32 - copy ELF note segments in a given buffer
*
* @ehdr_ptr: ELF header
* @notes_buf: buffer into which ELF note segments are copied
*
* This function is used to copy ELF note segment in the 1st kernel
* into the buffer @notes_buf in the 2nd kernel. It is assumed that
* size of the buffer @notes_buf is equal to or larger than sum of the
* real ELF note segment headers and data.
*
* It is assumed that program headers with PT_NOTE type pointed to by
* @ehdr_ptr has already been updated by update_note_header_size_elf32
* and each of PT_NOTE program headers has actual ELF note segment
* size in its p_memsz member.
*/
static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
{
int i, rc=0;
Elf32_Phdr *phdr_ptr;
phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
u64 offset;
if (phdr_ptr->p_type != PT_NOTE)
continue;
offset = phdr_ptr->p_offset;
rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
&offset);
if (rc < 0)
return rc;
notes_buf += phdr_ptr->p_memsz;
}
return 0;
}
/* Merges all the PT_NOTE headers into one. */
static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
char **notes_buf, size_t *notes_sz)
{
int i, nr_ptnote=0, rc=0;
char *tmp;
Elf32_Ehdr *ehdr_ptr;
Elf32_Phdr phdr;
u64 phdr_sz = 0, note_off;
ehdr_ptr = (Elf32_Ehdr *)elfptr;
rc = update_note_header_size_elf32(ehdr_ptr);
if (rc < 0)
return rc;
rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
if (rc < 0)
return rc;
*notes_sz = roundup(phdr_sz, PAGE_SIZE);
*notes_buf = alloc_elfnotes_buf(*notes_sz);
if (!*notes_buf)
return -ENOMEM;
rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
if (rc < 0)
return rc;
/* Prepare merged PT_NOTE program header. */
phdr.p_type = PT_NOTE;
phdr.p_flags = 0;
note_off = sizeof(Elf32_Ehdr) +
(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
phdr.p_offset = roundup(note_off, PAGE_SIZE);
phdr.p_vaddr = phdr.p_paddr = 0;
phdr.p_filesz = phdr.p_memsz = phdr_sz;
phdr.p_align = 0;
/* Add merged PT_NOTE program header*/
tmp = elfptr + sizeof(Elf32_Ehdr);
memcpy(tmp, &phdr, sizeof(phdr));
tmp += sizeof(phdr);
/* Remove unwanted PT_NOTE program headers. */
i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
*elfsz = *elfsz - i;
memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
memset(elfptr + *elfsz, 0, i);
*elfsz = roundup(*elfsz, PAGE_SIZE);
/* Modify e_phnum to reflect merged headers. */
ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
return 0;
}
/* Add memory chunks represented by program headers to vmcore list. Also update
* the new offset fields of exported program headers. */
static int __init process_ptload_program_headers_elf64(char *elfptr,
size_t elfsz,
size_t elfnotes_sz,
struct list_head *vc_list)
{
int i;
Elf64_Ehdr *ehdr_ptr;
Elf64_Phdr *phdr_ptr;
loff_t vmcore_off;
struct vmcore *new;
ehdr_ptr = (Elf64_Ehdr *)elfptr;
phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
/* Skip Elf header, program headers and Elf note segment. */
vmcore_off = elfsz + elfnotes_sz;
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
u64 paddr, start, end, size;
if (phdr_ptr->p_type != PT_LOAD)
continue;
paddr = phdr_ptr->p_offset;
start = rounddown(paddr, PAGE_SIZE);
end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
size = end - start;
/* Add this contiguous chunk of memory to vmcore list.*/
new = get_new_element();
if (!new)
return -ENOMEM;
new->paddr = start;
new->size = size;
list_add_tail(&new->list, vc_list);
/* Update the program header offset. */
phdr_ptr->p_offset = vmcore_off + (paddr - start);
vmcore_off = vmcore_off + size;
}
return 0;
}
static int __init process_ptload_program_headers_elf32(char *elfptr,
size_t elfsz,
size_t elfnotes_sz,
struct list_head *vc_list)
{
int i;
Elf32_Ehdr *ehdr_ptr;
Elf32_Phdr *phdr_ptr;
loff_t vmcore_off;
struct vmcore *new;
ehdr_ptr = (Elf32_Ehdr *)elfptr;
phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
/* Skip Elf header, program headers and Elf note segment. */
vmcore_off = elfsz + elfnotes_sz;
for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
u64 paddr, start, end, size;
if (phdr_ptr->p_type != PT_LOAD)
continue;
paddr = phdr_ptr->p_offset;
start = rounddown(paddr, PAGE_SIZE);
end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
size = end - start;
/* Add this contiguous chunk of memory to vmcore list.*/
new = get_new_element();
if (!new)
return -ENOMEM;
new->paddr = start;
new->size = size;
list_add_tail(&new->list, vc_list);
/* Update the program header offset */
phdr_ptr->p_offset = vmcore_off + (paddr - start);
vmcore_off = vmcore_off + size;
}
return 0;
}
/* Sets offset fields of vmcore elements. */
static void __init set_vmcore_list_offsets(size_t elfsz, size_t elfnotes_sz,
struct list_head *vc_list)
{
loff_t vmcore_off;
struct vmcore *m;
/* Skip Elf header, program headers and Elf note segment. */
vmcore_off = elfsz + elfnotes_sz;
list_for_each_entry(m, vc_list, list) {
m->offset = vmcore_off;
vmcore_off += m->size;
}
}
static void free_elfcorebuf(void)
{
free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
elfcorebuf = NULL;
vfree(elfnotes_buf);
elfnotes_buf = NULL;
}
static int __init parse_crash_elf64_headers(void)
{
int rc=0;
Elf64_Ehdr ehdr;
u64 addr;
addr = elfcorehdr_addr;
/* Read Elf header */
rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr);
if (rc < 0)
return rc;
/* Do some basic Verification. */
if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
(ehdr.e_type != ET_CORE) ||
!vmcore_elf64_check_arch(&ehdr) ||
ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
ehdr.e_version != EV_CURRENT ||
ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
ehdr.e_phnum == 0) {
pr_warn("Warning: Core image elf header is not sane\n");
return -EINVAL;
}
/* Read in all elf headers. */
elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) +
ehdr.e_phnum * sizeof(Elf64_Phdr);
elfcorebuf_sz = elfcorebuf_sz_orig;
elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
get_order(elfcorebuf_sz_orig));
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
if (rc < 0)
goto fail;
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
&elfnotes_buf, &elfnotes_sz);
if (rc)
goto fail;
rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
elfnotes_sz, &vmcore_list);
if (rc)
goto fail;
set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
return 0;
fail:
free_elfcorebuf();
return rc;
}
static int __init parse_crash_elf32_headers(void)
{
int rc=0;
Elf32_Ehdr ehdr;
u64 addr;
addr = elfcorehdr_addr;
/* Read Elf header */
rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr);
if (rc < 0)
return rc;
/* Do some basic Verification. */
if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
(ehdr.e_type != ET_CORE) ||
!elf_check_arch(&ehdr) ||
ehdr.e_ident[EI_CLASS] != ELFCLASS32||
ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
ehdr.e_version != EV_CURRENT ||
ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
ehdr.e_phnum == 0) {
pr_warn("Warning: Core image elf header is not sane\n");
return -EINVAL;
}
/* Read in all elf headers. */
elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
elfcorebuf_sz = elfcorebuf_sz_orig;
elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
get_order(elfcorebuf_sz_orig));
if (!elfcorebuf)
return -ENOMEM;
addr = elfcorehdr_addr;
rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
if (rc < 0)
goto fail;
/* Merge all PT_NOTE headers into one. */
rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
&elfnotes_buf, &elfnotes_sz);
if (rc)
goto fail;
rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
elfnotes_sz, &vmcore_list);
if (rc)
goto fail;
set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
return 0;
fail:
free_elfcorebuf();
return rc;
}
static int __init parse_crash_elf_headers(void)
{
unsigned char e_ident[EI_NIDENT];
u64 addr;
int rc=0;
addr = elfcorehdr_addr;
rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr);
if (rc < 0)
return rc;
if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
pr_warn("Warning: Core image elf header not found\n");
return -EINVAL;
}
if (e_ident[EI_CLASS] == ELFCLASS64) {
rc = parse_crash_elf64_headers();
if (rc)
return rc;
} else if (e_ident[EI_CLASS] == ELFCLASS32) {
rc = parse_crash_elf32_headers();
if (rc)
return rc;
} else {
pr_warn("Warning: Core image elf header is not sane\n");
return -EINVAL;
}
/* Determine vmcore size. */
vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
&vmcore_list);
return 0;
}
/* Init function for vmcore module. */
static int __init vmcore_init(void)
{
int rc = 0;
/* Allow architectures to allocate ELF header in 2nd kernel */
rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
if (rc)
return rc;
/*
* If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
* then capture the dump.
*/
if (!(is_vmcore_usable()))
return rc;
rc = parse_crash_elf_headers();
if (rc) {
pr_warn("Kdump: vmcore not initialized\n");
return rc;
}
elfcorehdr_free(elfcorehdr_addr);
elfcorehdr_addr = ELFCORE_ADDR_ERR;
proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
if (proc_vmcore)
proc_vmcore->size = vmcore_size;
return 0;
}
fs_initcall(vmcore_init);
/* Cleanup function for vmcore module. */
void vmcore_cleanup(void)
{
struct list_head *pos, *next;
if (proc_vmcore) {
proc_remove(proc_vmcore);
proc_vmcore = NULL;
}
/* clear the vmcore list. */
list_for_each_safe(pos, next, &vmcore_list) {
struct vmcore *m;
m = list_entry(pos, struct vmcore, list);
list_del(&m->list);
kfree(m);
}
free_elfcorebuf();
}