305 lines
8.2 KiB
C
305 lines
8.2 KiB
C
|
// SPDX-License-Identifier: GPL-2.0-or-later
|
||
|
|
/*
|
||
|
|
* linux/mm/process_vm_access.c
|
||
|
|
*
|
||
|
|
* Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/compat.h>
|
||
|
|
#include <linux/mm.h>
|
||
|
|
#include <linux/uio.h>
|
||
|
|
#include <linux/sched.h>
|
||
|
|
#include <linux/sched/mm.h>
|
||
|
|
#include <linux/highmem.h>
|
||
|
|
#include <linux/ptrace.h>
|
||
|
|
#include <linux/slab.h>
|
||
|
|
#include <linux/syscalls.h>
|
||
|
|
|
||
|
|
/**
|
||
|
|
* process_vm_rw_pages - read/write pages from task specified
|
||
|
|
* @pages: array of pointers to pages we want to copy
|
||
|
|
* @offset: offset in page to start copying from/to
|
||
|
|
* @len: number of bytes to copy
|
||
|
|
* @iter: where to copy to/from locally
|
||
|
|
* @vm_write: 0 means copy from, 1 means copy to
|
||
|
|
* Returns 0 on success, error code otherwise
|
||
|
|
*/
|
||
|
|
static int process_vm_rw_pages(struct page **pages,
|
||
|
|
unsigned offset,
|
||
|
|
size_t len,
|
||
|
|
struct iov_iter *iter,
|
||
|
|
int vm_write)
|
||
|
|
{
|
||
|
|
/* Do the copy for each page */
|
||
|
|
while (len && iov_iter_count(iter)) {
|
||
|
|
struct page *page = *pages++;
|
||
|
|
size_t copy = PAGE_SIZE - offset;
|
||
|
|
size_t copied;
|
||
|
|
|
||
|
|
if (copy > len)
|
||
|
|
copy = len;
|
||
|
|
|
||
|
|
if (vm_write)
|
||
|
|
copied = copy_page_from_iter(page, offset, copy, iter);
|
||
|
|
else
|
||
|
|
copied = copy_page_to_iter(page, offset, copy, iter);
|
||
|
|
|
||
|
|
len -= copied;
|
||
|
|
if (copied < copy && iov_iter_count(iter))
|
||
|
|
return -EFAULT;
|
||
|
|
offset = 0;
|
||
|
|
}
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Maximum number of pages kmalloc'd to hold struct page's during copy */
|
||
|
|
#define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
|
||
|
|
|
||
|
|
/**
|
||
|
|
* process_vm_rw_single_vec - read/write pages from task specified
|
||
|
|
* @addr: start memory address of target process
|
||
|
|
* @len: size of area to copy to/from
|
||
|
|
* @iter: where to copy to/from locally
|
||
|
|
* @process_pages: struct pages area that can store at least
|
||
|
|
* nr_pages_to_copy struct page pointers
|
||
|
|
* @mm: mm for task
|
||
|
|
* @task: task to read/write from
|
||
|
|
* @vm_write: 0 means copy from, 1 means copy to
|
||
|
|
* Returns 0 on success or on failure error code
|
||
|
|
*/
|
||
|
|
static int process_vm_rw_single_vec(unsigned long addr,
|
||
|
|
unsigned long len,
|
||
|
|
struct iov_iter *iter,
|
||
|
|
struct page **process_pages,
|
||
|
|
struct mm_struct *mm,
|
||
|
|
struct task_struct *task,
|
||
|
|
int vm_write)
|
||
|
|
{
|
||
|
|
unsigned long pa = addr & PAGE_MASK;
|
||
|
|
unsigned long start_offset = addr - pa;
|
||
|
|
unsigned long nr_pages;
|
||
|
|
ssize_t rc = 0;
|
||
|
|
unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
|
||
|
|
/ sizeof(struct pages *);
|
||
|
|
unsigned int flags = 0;
|
||
|
|
|
||
|
|
/* Work out address and page range required */
|
||
|
|
if (len == 0)
|
||
|
|
return 0;
|
||
|
|
nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
|
||
|
|
|
||
|
|
if (vm_write)
|
||
|
|
flags |= FOLL_WRITE;
|
||
|
|
|
||
|
|
while (!rc && nr_pages && iov_iter_count(iter)) {
|
||
|
|
int pinned_pages = min(nr_pages, max_pages_per_loop);
|
||
|
|
int locked = 1;
|
||
|
|
size_t bytes;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Get the pages we're interested in. We must
|
||
|
|
* access remotely because task/mm might not
|
||
|
|
* current/current->mm
|
||
|
|
*/
|
||
|
|
mmap_read_lock(mm);
|
||
|
|
pinned_pages = pin_user_pages_remote(mm, pa, pinned_pages,
|
||
|
|
flags, process_pages,
|
||
|
|
NULL, &locked);
|
||
|
|
if (locked)
|
||
|
|
mmap_read_unlock(mm);
|
||
|
|
if (pinned_pages <= 0)
|
||
|
|
return -EFAULT;
|
||
|
|
|
||
|
|
bytes = pinned_pages * PAGE_SIZE - start_offset;
|
||
|
|
if (bytes > len)
|
||
|
|
bytes = len;
|
||
|
|
|
||
|
|
rc = process_vm_rw_pages(process_pages,
|
||
|
|
start_offset, bytes, iter,
|
||
|
|
vm_write);
|
||
|
|
len -= bytes;
|
||
|
|
start_offset = 0;
|
||
|
|
nr_pages -= pinned_pages;
|
||
|
|
pa += pinned_pages * PAGE_SIZE;
|
||
|
|
|
||
|
|
/* If vm_write is set, the pages need to be made dirty: */
|
||
|
|
unpin_user_pages_dirty_lock(process_pages, pinned_pages,
|
||
|
|
vm_write);
|
||
|
|
}
|
||
|
|
|
||
|
|
return rc;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Maximum number of entries for process pages array
|
||
|
|
which lives on stack */
|
||
|
|
#define PVM_MAX_PP_ARRAY_COUNT 16
|
||
|
|
|
||
|
|
/**
|
||
|
|
* process_vm_rw_core - core of reading/writing pages from task specified
|
||
|
|
* @pid: PID of process to read/write from/to
|
||
|
|
* @iter: where to copy to/from locally
|
||
|
|
* @rvec: iovec array specifying where to copy to/from in the other process
|
||
|
|
* @riovcnt: size of rvec array
|
||
|
|
* @flags: currently unused
|
||
|
|
* @vm_write: 0 if reading from other process, 1 if writing to other process
|
||
|
|
*
|
||
|
|
* Returns the number of bytes read/written or error code. May
|
||
|
|
* return less bytes than expected if an error occurs during the copying
|
||
|
|
* process.
|
||
|
|
*/
|
||
|
|
static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
|
||
|
|
const struct iovec *rvec,
|
||
|
|
unsigned long riovcnt,
|
||
|
|
unsigned long flags, int vm_write)
|
||
|
|
{
|
||
|
|
struct task_struct *task;
|
||
|
|
struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
|
||
|
|
struct page **process_pages = pp_stack;
|
||
|
|
struct mm_struct *mm;
|
||
|
|
unsigned long i;
|
||
|
|
ssize_t rc = 0;
|
||
|
|
unsigned long nr_pages = 0;
|
||
|
|
unsigned long nr_pages_iov;
|
||
|
|
ssize_t iov_len;
|
||
|
|
size_t total_len = iov_iter_count(iter);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Work out how many pages of struct pages we're going to need
|
||
|
|
* when eventually calling get_user_pages
|
||
|
|
*/
|
||
|
|
for (i = 0; i < riovcnt; i++) {
|
||
|
|
iov_len = rvec[i].iov_len;
|
||
|
|
if (iov_len > 0) {
|
||
|
|
nr_pages_iov = ((unsigned long)rvec[i].iov_base
|
||
|
|
+ iov_len)
|
||
|
|
/ PAGE_SIZE - (unsigned long)rvec[i].iov_base
|
||
|
|
/ PAGE_SIZE + 1;
|
||
|
|
nr_pages = max(nr_pages, nr_pages_iov);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (nr_pages == 0)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
|
||
|
|
/* For reliability don't try to kmalloc more than
|
||
|
|
2 pages worth */
|
||
|
|
process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
|
||
|
|
sizeof(struct pages *)*nr_pages),
|
||
|
|
GFP_KERNEL);
|
||
|
|
|
||
|
|
if (!process_pages)
|
||
|
|
return -ENOMEM;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Get process information */
|
||
|
|
task = find_get_task_by_vpid(pid);
|
||
|
|
if (!task) {
|
||
|
|
rc = -ESRCH;
|
||
|
|
goto free_proc_pages;
|
||
|
|
}
|
||
|
|
|
||
|
|
mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS);
|
||
|
|
if (!mm || IS_ERR(mm)) {
|
||
|
|
rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
|
||
|
|
/*
|
||
|
|
* Explicitly map EACCES to EPERM as EPERM is a more
|
||
|
|
* appropriate error code for process_vw_readv/writev
|
||
|
|
*/
|
||
|
|
if (rc == -EACCES)
|
||
|
|
rc = -EPERM;
|
||
|
|
goto put_task_struct;
|
||
|
|
}
|
||
|
|
|
||
|
|
for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
|
||
|
|
rc = process_vm_rw_single_vec(
|
||
|
|
(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
|
||
|
|
iter, process_pages, mm, task, vm_write);
|
||
|
|
|
||
|
|
/* copied = space before - space after */
|
||
|
|
total_len -= iov_iter_count(iter);
|
||
|
|
|
||
|
|
/* If we have managed to copy any data at all then
|
||
|
|
we return the number of bytes copied. Otherwise
|
||
|
|
we return the error code */
|
||
|
|
if (total_len)
|
||
|
|
rc = total_len;
|
||
|
|
|
||
|
|
mmput(mm);
|
||
|
|
|
||
|
|
put_task_struct:
|
||
|
|
put_task_struct(task);
|
||
|
|
|
||
|
|
free_proc_pages:
|
||
|
|
if (process_pages != pp_stack)
|
||
|
|
kfree(process_pages);
|
||
|
|
return rc;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* process_vm_rw - check iovecs before calling core routine
|
||
|
|
* @pid: PID of process to read/write from/to
|
||
|
|
* @lvec: iovec array specifying where to copy to/from locally
|
||
|
|
* @liovcnt: size of lvec array
|
||
|
|
* @rvec: iovec array specifying where to copy to/from in the other process
|
||
|
|
* @riovcnt: size of rvec array
|
||
|
|
* @flags: currently unused
|
||
|
|
* @vm_write: 0 if reading from other process, 1 if writing to other process
|
||
|
|
*
|
||
|
|
* Returns the number of bytes read/written or error code. May
|
||
|
|
* return less bytes than expected if an error occurs during the copying
|
||
|
|
* process.
|
||
|
|
*/
|
||
|
|
static ssize_t process_vm_rw(pid_t pid,
|
||
|
|
const struct iovec __user *lvec,
|
||
|
|
unsigned long liovcnt,
|
||
|
|
const struct iovec __user *rvec,
|
||
|
|
unsigned long riovcnt,
|
||
|
|
unsigned long flags, int vm_write)
|
||
|
|
{
|
||
|
|
struct iovec iovstack_l[UIO_FASTIOV];
|
||
|
|
struct iovec iovstack_r[UIO_FASTIOV];
|
||
|
|
struct iovec *iov_l = iovstack_l;
|
||
|
|
struct iovec *iov_r;
|
||
|
|
struct iov_iter iter;
|
||
|
|
ssize_t rc;
|
||
|
|
int dir = vm_write ? ITER_SOURCE : ITER_DEST;
|
||
|
|
|
||
|
|
if (flags != 0)
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
/* Check iovecs */
|
||
|
|
rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
|
||
|
|
if (rc < 0)
|
||
|
|
return rc;
|
||
|
|
if (!iov_iter_count(&iter))
|
||
|
|
goto free_iov_l;
|
||
|
|
iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r,
|
||
|
|
in_compat_syscall());
|
||
|
|
if (IS_ERR(iov_r)) {
|
||
|
|
rc = PTR_ERR(iov_r);
|
||
|
|
goto free_iov_l;
|
||
|
|
}
|
||
|
|
rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
|
||
|
|
if (iov_r != iovstack_r)
|
||
|
|
kfree(iov_r);
|
||
|
|
free_iov_l:
|
||
|
|
kfree(iov_l);
|
||
|
|
return rc;
|
||
|
|
}
|
||
|
|
|
||
|
|
SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
|
||
|
|
unsigned long, liovcnt, const struct iovec __user *, rvec,
|
||
|
|
unsigned long, riovcnt, unsigned long, flags)
|
||
|
|
{
|
||
|
|
return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
|
||
|
|
}
|
||
|
|
|
||
|
|
SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
|
||
|
|
const struct iovec __user *, lvec,
|
||
|
|
unsigned long, liovcnt, const struct iovec __user *, rvec,
|
||
|
|
unsigned long, riovcnt, unsigned long, flags)
|
||
|
|
{
|
||
|
|
return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
|
||
|
|
}
|