linux/fs/proc/kcore.c
Dominique Martinet a1b3d2f217 fs/proc/kcore.c: fix invalid memory access in multi-page read optimization
The 'm' kcore_list item could point to kclist_head, and it is incorrect to
look at m->addr / m->size in this case.

There is no choice but to run through the list of entries for every
address if we did not find any entry in the previous iteration

Reset 'm' to NULL in that case at Omar Sandoval's suggestion.

[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/1536100702-28706-1-git-send-email-asmadeus@codewreck.org
Fixes: bf991c2231 ("proc/kcore: optimize multiple page reads")
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Omar Sandoval <osandov@osandov.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-20 22:01:11 +02:00

626 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* fs/proc/kcore.c kernel ELF core dumper
*
* Modelled on fs/exec.c:aout_core_dump()
* Jeremy Fitzhardinge <jeremy@sw.oz.au>
* ELF version written by David Howells <David.Howells@nexor.co.uk>
* Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
* Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
* Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
*/
#include <linux/crash_core.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/kcore.h>
#include <linux/user.h>
#include <linux/capability.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/notifier.h>
#include <linux/vmalloc.h>
#include <linux/highmem.h>
#include <linux/printk.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/io.h>
#include <linux/list.h>
#include <linux/ioport.h>
#include <linux/memory.h>
#include <linux/sched/task.h>
#include <asm/sections.h>
#include "internal.h"
#define CORE_STR "CORE"
#ifndef ELF_CORE_EFLAGS
#define ELF_CORE_EFLAGS 0
#endif
static struct proc_dir_entry *proc_root_kcore;
#ifndef kc_vaddr_to_offset
#define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
#endif
#ifndef kc_offset_to_vaddr
#define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
#endif
static LIST_HEAD(kclist_head);
static DECLARE_RWSEM(kclist_lock);
static int kcore_need_update = 1;
/* This doesn't grab kclist_lock, so it should only be used at init time. */
void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
int type)
{
new->addr = (unsigned long)addr;
new->size = size;
new->type = type;
list_add_tail(&new->list, &kclist_head);
}
static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
size_t *data_offset)
{
size_t try, size;
struct kcore_list *m;
*nphdr = 1; /* PT_NOTE */
size = 0;
list_for_each_entry(m, &kclist_head, list) {
try = kc_vaddr_to_offset((size_t)m->addr + m->size);
if (try > size)
size = try;
*nphdr = *nphdr + 1;
}
*phdrs_len = *nphdr * sizeof(struct elf_phdr);
*notes_len = (4 * sizeof(struct elf_note) +
3 * ALIGN(sizeof(CORE_STR), 4) +
VMCOREINFO_NOTE_NAME_BYTES +
ALIGN(sizeof(struct elf_prstatus), 4) +
ALIGN(sizeof(struct elf_prpsinfo), 4) +
ALIGN(arch_task_struct_size, 4) +
ALIGN(vmcoreinfo_size, 4));
*data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
*notes_len);
return *data_offset + size;
}
#ifdef CONFIG_HIGHMEM
/*
* If no highmem, we can assume [0...max_low_pfn) continuous range of memory
* because memory hole is not as big as !HIGHMEM case.
* (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
*/
static int kcore_ram_list(struct list_head *head)
{
struct kcore_list *ent;
ent = kmalloc(sizeof(*ent), GFP_KERNEL);
if (!ent)
return -ENOMEM;
ent->addr = (unsigned long)__va(0);
ent->size = max_low_pfn << PAGE_SHIFT;
ent->type = KCORE_RAM;
list_add(&ent->list, head);
return 0;
}
#else /* !CONFIG_HIGHMEM */
#ifdef CONFIG_SPARSEMEM_VMEMMAP
/* calculate vmemmap's address from given system ram pfn and register it */
static int
get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
{
unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
unsigned long nr_pages = ent->size >> PAGE_SHIFT;
unsigned long start, end;
struct kcore_list *vmm, *tmp;
start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
end = PAGE_ALIGN(end);
/* overlap check (because we have to align page */
list_for_each_entry(tmp, head, list) {
if (tmp->type != KCORE_VMEMMAP)
continue;
if (start < tmp->addr + tmp->size)
if (end > tmp->addr)
end = tmp->addr;
}
if (start < end) {
vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
if (!vmm)
return 0;
vmm->addr = start;
vmm->size = end - start;
vmm->type = KCORE_VMEMMAP;
list_add_tail(&vmm->list, head);
}
return 1;
}
#else
static int
get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
{
return 1;
}
#endif
static int
kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
{
struct list_head *head = (struct list_head *)arg;
struct kcore_list *ent;
struct page *p;
if (!pfn_valid(pfn))
return 1;
p = pfn_to_page(pfn);
if (!memmap_valid_within(pfn, p, page_zone(p)))
return 1;
ent = kmalloc(sizeof(*ent), GFP_KERNEL);
if (!ent)
return -ENOMEM;
ent->addr = (unsigned long)page_to_virt(p);
ent->size = nr_pages << PAGE_SHIFT;
if (!virt_addr_valid(ent->addr))
goto free_out;
/* cut not-mapped area. ....from ppc-32 code. */
if (ULONG_MAX - ent->addr < ent->size)
ent->size = ULONG_MAX - ent->addr;
/*
* We've already checked virt_addr_valid so we know this address
* is a valid pointer, therefore we can check against it to determine
* if we need to trim
*/
if (VMALLOC_START > ent->addr) {
if (VMALLOC_START - ent->addr < ent->size)
ent->size = VMALLOC_START - ent->addr;
}
ent->type = KCORE_RAM;
list_add_tail(&ent->list, head);
if (!get_sparsemem_vmemmap_info(ent, head)) {
list_del(&ent->list);
goto free_out;
}
return 0;
free_out:
kfree(ent);
return 1;
}
static int kcore_ram_list(struct list_head *list)
{
int nid, ret;
unsigned long end_pfn;
/* Not inialized....update now */
/* find out "max pfn" */
end_pfn = 0;
for_each_node_state(nid, N_MEMORY) {
unsigned long node_end;
node_end = node_end_pfn(nid);
if (end_pfn < node_end)
end_pfn = node_end;
}
/* scan 0 to max_pfn */
ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
if (ret)
return -ENOMEM;
return 0;
}
#endif /* CONFIG_HIGHMEM */
static int kcore_update_ram(void)
{
LIST_HEAD(list);
LIST_HEAD(garbage);
int nphdr;
size_t phdrs_len, notes_len, data_offset;
struct kcore_list *tmp, *pos;
int ret = 0;
down_write(&kclist_lock);
if (!xchg(&kcore_need_update, 0))
goto out;
ret = kcore_ram_list(&list);
if (ret) {
/* Couldn't get the RAM list, try again next time. */
WRITE_ONCE(kcore_need_update, 1);
list_splice_tail(&list, &garbage);
goto out;
}
list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
list_move(&pos->list, &garbage);
}
list_splice_tail(&list, &kclist_head);
proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, &notes_len,
&data_offset);
out:
up_write(&kclist_lock);
list_for_each_entry_safe(pos, tmp, &garbage, list) {
list_del(&pos->list);
kfree(pos);
}
return ret;
}
static void append_kcore_note(char *notes, size_t *i, const char *name,
unsigned int type, const void *desc,
size_t descsz)
{
struct elf_note *note = (struct elf_note *)&notes[*i];
note->n_namesz = strlen(name) + 1;
note->n_descsz = descsz;
note->n_type = type;
*i += sizeof(*note);
memcpy(&notes[*i], name, note->n_namesz);
*i = ALIGN(*i + note->n_namesz, 4);
memcpy(&notes[*i], desc, descsz);
*i = ALIGN(*i + descsz, 4);
}
static ssize_t
read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
{
char *buf = file->private_data;
size_t phdrs_offset, notes_offset, data_offset;
size_t phdrs_len, notes_len;
struct kcore_list *m;
size_t tsz;
int nphdr;
unsigned long start;
size_t orig_buflen = buflen;
int ret = 0;
down_read(&kclist_lock);
get_kcore_size(&nphdr, &phdrs_len, &notes_len, &data_offset);
phdrs_offset = sizeof(struct elfhdr);
notes_offset = phdrs_offset + phdrs_len;
/* ELF file header. */
if (buflen && *fpos < sizeof(struct elfhdr)) {
struct elfhdr ehdr = {
.e_ident = {
[EI_MAG0] = ELFMAG0,
[EI_MAG1] = ELFMAG1,
[EI_MAG2] = ELFMAG2,
[EI_MAG3] = ELFMAG3,
[EI_CLASS] = ELF_CLASS,
[EI_DATA] = ELF_DATA,
[EI_VERSION] = EV_CURRENT,
[EI_OSABI] = ELF_OSABI,
},
.e_type = ET_CORE,
.e_machine = ELF_ARCH,
.e_version = EV_CURRENT,
.e_phoff = sizeof(struct elfhdr),
.e_flags = ELF_CORE_EFLAGS,
.e_ehsize = sizeof(struct elfhdr),
.e_phentsize = sizeof(struct elf_phdr),
.e_phnum = nphdr,
};
tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) {
ret = -EFAULT;
goto out;
}
buffer += tsz;
buflen -= tsz;
*fpos += tsz;
}
/* ELF program headers. */
if (buflen && *fpos < phdrs_offset + phdrs_len) {
struct elf_phdr *phdrs, *phdr;
phdrs = kzalloc(phdrs_len, GFP_KERNEL);
if (!phdrs) {
ret = -ENOMEM;
goto out;
}
phdrs[0].p_type = PT_NOTE;
phdrs[0].p_offset = notes_offset;
phdrs[0].p_filesz = notes_len;
phdr = &phdrs[1];
list_for_each_entry(m, &kclist_head, list) {
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R | PF_W | PF_X;
phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
if (m->type == KCORE_REMAP)
phdr->p_vaddr = (size_t)m->vaddr;
else
phdr->p_vaddr = (size_t)m->addr;
if (m->type == KCORE_RAM || m->type == KCORE_REMAP)
phdr->p_paddr = __pa(m->addr);
else if (m->type == KCORE_TEXT)
phdr->p_paddr = __pa_symbol(m->addr);
else
phdr->p_paddr = (elf_addr_t)-1;
phdr->p_filesz = phdr->p_memsz = m->size;
phdr->p_align = PAGE_SIZE;
phdr++;
}
tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset,
tsz)) {
kfree(phdrs);
ret = -EFAULT;
goto out;
}
kfree(phdrs);
buffer += tsz;
buflen -= tsz;
*fpos += tsz;
}
/* ELF note segment. */
if (buflen && *fpos < notes_offset + notes_len) {
struct elf_prstatus prstatus = {};
struct elf_prpsinfo prpsinfo = {
.pr_sname = 'R',
.pr_fname = "vmlinux",
};
char *notes;
size_t i = 0;
strlcpy(prpsinfo.pr_psargs, saved_command_line,
sizeof(prpsinfo.pr_psargs));
notes = kzalloc(notes_len, GFP_KERNEL);
if (!notes) {
ret = -ENOMEM;
goto out;
}
append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
sizeof(prstatus));
append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
sizeof(prpsinfo));
append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
arch_task_struct_size);
/*
* vmcoreinfo_size is mostly constant after init time, but it
* can be changed by crash_save_vmcoreinfo(). Racing here with a
* panic on another CPU before the machine goes down is insanely
* unlikely, but it's better to not leave potential buffer
* overflows lying around, regardless.
*/
append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
vmcoreinfo_data,
min(vmcoreinfo_size, notes_len - i));
tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
kfree(notes);
ret = -EFAULT;
goto out;
}
kfree(notes);
buffer += tsz;
buflen -= tsz;
*fpos += tsz;
}
/*
* Check to see if our file offset matches with any of
* the addresses in the elf_phdr on our list.
*/
start = kc_offset_to_vaddr(*fpos - data_offset);
if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
tsz = buflen;
m = NULL;
while (buflen) {
/*
* If this is the first iteration or the address is not within
* the previous entry, search for a matching entry.
*/
if (!m || start < m->addr || start >= m->addr + m->size) {
list_for_each_entry(m, &kclist_head, list) {
if (start >= m->addr &&
start < m->addr + m->size)
break;
}
}
if (&m->list == &kclist_head) {
if (clear_user(buffer, tsz)) {
ret = -EFAULT;
goto out;
}
m = NULL; /* skip the list anchor */
} else if (m->type == KCORE_VMALLOC) {
vread(buf, (char *)start, tsz);
/* we have to zero-fill user buffer even if no read */
if (copy_to_user(buffer, buf, tsz)) {
ret = -EFAULT;
goto out;
}
} else if (m->type == KCORE_USER) {
/* User page is handled prior to normal kernel page: */
if (copy_to_user(buffer, (char *)start, tsz)) {
ret = -EFAULT;
goto out;
}
} else {
if (kern_addr_valid(start)) {
/*
* Using bounce buffer to bypass the
* hardened user copy kernel text checks.
*/
if (probe_kernel_read(buf, (void *) start, tsz)) {
if (clear_user(buffer, tsz)) {
ret = -EFAULT;
goto out;
}
} else {
if (copy_to_user(buffer, buf, tsz)) {
ret = -EFAULT;
goto out;
}
}
} else {
if (clear_user(buffer, tsz)) {
ret = -EFAULT;
goto out;
}
}
}
buflen -= tsz;
*fpos += tsz;
buffer += tsz;
start += tsz;
tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
}
out:
up_read(&kclist_lock);
if (ret)
return ret;
return orig_buflen - buflen;
}
static int open_kcore(struct inode *inode, struct file *filp)
{
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!filp->private_data)
return -ENOMEM;
if (kcore_need_update)
kcore_update_ram();
if (i_size_read(inode) != proc_root_kcore->size) {
inode_lock(inode);
i_size_write(inode, proc_root_kcore->size);
inode_unlock(inode);
}
return 0;
}
static int release_kcore(struct inode *inode, struct file *file)
{
kfree(file->private_data);
return 0;
}
static const struct file_operations proc_kcore_operations = {
.read = read_kcore,
.open = open_kcore,
.release = release_kcore,
.llseek = default_llseek,
};
/* just remember that we have to update kcore */
static int __meminit kcore_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
switch (action) {
case MEM_ONLINE:
case MEM_OFFLINE:
kcore_need_update = 1;
break;
}
return NOTIFY_OK;
}
static struct notifier_block kcore_callback_nb __meminitdata = {
.notifier_call = kcore_callback,
.priority = 0,
};
static struct kcore_list kcore_vmalloc;
#ifdef CONFIG_ARCH_PROC_KCORE_TEXT
static struct kcore_list kcore_text;
/*
* If defined, special segment is used for mapping kernel text instead of
* direct-map area. We need to create special TEXT section.
*/
static void __init proc_kcore_text_init(void)
{
kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
}
#else
static void __init proc_kcore_text_init(void)
{
}
#endif
#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
/*
* MODULES_VADDR has no intersection with VMALLOC_ADDR.
*/
struct kcore_list kcore_modules;
static void __init add_modules_range(void)
{
if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
kclist_add(&kcore_modules, (void *)MODULES_VADDR,
MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
}
}
#else
static void __init add_modules_range(void)
{
}
#endif
static int __init proc_kcore_init(void)
{
proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
&proc_kcore_operations);
if (!proc_root_kcore) {
pr_err("couldn't create /proc/kcore\n");
return 0; /* Always returns 0. */
}
/* Store text area if it's special */
proc_kcore_text_init();
/* Store vmalloc area */
kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
add_modules_range();
/* Store direct-map area from physical memory map */
kcore_update_ram();
register_hotmemory_notifier(&kcore_callback_nb);
return 0;
}
fs_initcall(proc_kcore_init);