--- /dev/null
+/*
+ * linux/mm/process_vm_access.c
+ *
+ * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/mm.h>
+#include <linux/uio.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+#endif
+
+/**
+ * process_vm_rw_pages - read/write pages from task specified
+ * @task: task to read/write from
+ * @mm: mm for task
+ * @process_pages: struct pages area that can store at least
+ * nr_pages_to_copy struct page pointers
+ * @pa: address of page in task to start copying from/to
+ * @start_offset: offset in page to start copying from/to
+ * @len: number of bytes to copy
+ * @lvec: iovec array specifying where to copy to/from
+ * @lvec_cnt: number of elements in iovec array
+ * @lvec_current: index in iovec array we are up to
+ * @lvec_offset: offset in bytes from current iovec iov_base we are up to
+ * @vm_write: 0 means copy from, 1 means copy to
+ * @nr_pages_to_copy: number of pages to copy
+ * @bytes_copied: returns number of bytes successfully copied
+ * Returns 0 on success, error code otherwise
+ */
+static int process_vm_rw_pages(struct task_struct *task,
+ struct mm_struct *mm,
+ struct page **process_pages,
+ unsigned long pa,
+ unsigned long start_offset,
+ unsigned long len,
+ const struct iovec *lvec,
+ unsigned long lvec_cnt,
+ unsigned long *lvec_current,
+ size_t *lvec_offset,
+ int vm_write,
+ unsigned int nr_pages_to_copy,
+ ssize_t *bytes_copied)
+{
+ int pages_pinned;
+ void *target_kaddr;
+ int pgs_copied = 0;
+ int j;
+ int ret;
+ ssize_t bytes_to_copy;
+ ssize_t rc = 0;
+
+ *bytes_copied = 0;
+
+ /* Get the pages we're interested in */
+ down_read(&mm->mmap_sem);
+ pages_pinned = get_user_pages(task, mm, pa,
+ nr_pages_to_copy,
+ vm_write, 0, process_pages, NULL);
+ up_read(&mm->mmap_sem);
+
+ if (pages_pinned != nr_pages_to_copy) {
+ rc = -EFAULT;
+ goto end;
+ }
+
+ /* Do the copy for each page */
+ for (pgs_copied = 0;
+ (pgs_copied < nr_pages_to_copy) && (*lvec_current < lvec_cnt);
+ pgs_copied++) {
+ /* Make sure we have a non zero length iovec */
+ while (*lvec_current < lvec_cnt
+ && lvec[*lvec_current].iov_len == 0)
+ (*lvec_current)++;
+ if (*lvec_current == lvec_cnt)
+ break;
+
+ /*
+ * Will copy smallest of:
+ * - bytes remaining in page
+ * - bytes remaining in destination iovec
+ */
+ bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
+ len - *bytes_copied);
+ bytes_to_copy = min_t(ssize_t, bytes_to_copy,
+ lvec[*lvec_current].iov_len
+ - *lvec_offset);
+
+ target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
+
+ if (vm_write)
+ ret = copy_from_user(target_kaddr,
+ lvec[*lvec_current].iov_base
+ + *lvec_offset,
+ bytes_to_copy);
+ else
+ ret = copy_to_user(lvec[*lvec_current].iov_base
+ + *lvec_offset,
+ target_kaddr, bytes_to_copy);
+ kunmap(process_pages[pgs_copied]);
+ if (ret) {
+ *bytes_copied += bytes_to_copy - ret;
+ pgs_copied++;
+ rc = -EFAULT;
+ goto end;
+ }
+ *bytes_copied += bytes_to_copy;
+ *lvec_offset += bytes_to_copy;
+ if (*lvec_offset == lvec[*lvec_current].iov_len) {
+ /*
+ * Need to copy remaining part of page into the
+ * next iovec if there are any bytes left in page
+ */
+ (*lvec_current)++;
+ *lvec_offset = 0;
+ start_offset = (start_offset + bytes_to_copy)
+ % PAGE_SIZE;
+ if (start_offset)
+ pgs_copied--;
+ } else {
+ start_offset = 0;
+ }
+ }
+
+end:
+ if (vm_write) {
+ for (j = 0; j < pages_pinned; j++) {
+ if (j < pgs_copied)
+ set_page_dirty_lock(process_pages[j]);
+ put_page(process_pages[j]);
+ }
+ } else {
+ for (j = 0; j < pages_pinned; j++)
+ put_page(process_pages[j]);
+ }
+
+ return rc;
+}
+
+/* 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
+ * @lvec: iovec array specifying where to copy to/from locally
+ * @lvec_cnt: number of elements in iovec array
+ * @lvec_current: index in iovec array we are up to
+ * @lvec_offset: offset in bytes from current iovec iov_base we are up to
+ * @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
+ * @bytes_copied: returns number of bytes successfully copied
+ * Returns 0 on success or on failure error code
+ */
+static int process_vm_rw_single_vec(unsigned long addr,
+ unsigned long len,
+ const struct iovec *lvec,
+ unsigned long lvec_cnt,
+ unsigned long *lvec_current,
+ size_t *lvec_offset,
+ struct page **process_pages,
+ struct mm_struct *mm,
+ struct task_struct *task,
+ int vm_write,
+ ssize_t *bytes_copied)
+{
+ unsigned long pa = addr & PAGE_MASK;
+ unsigned long start_offset = addr - pa;
+ unsigned long nr_pages;
+ ssize_t bytes_copied_loop;
+ ssize_t rc = 0;
+ unsigned long nr_pages_copied = 0;
+ unsigned long nr_pages_to_copy;
+ unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
+ / sizeof(struct pages *);
+
+ *bytes_copied = 0;
+
+ /* Work out address and page range required */
+ if (len == 0)
+ return 0;
+ nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
+
+ while ((nr_pages_copied < nr_pages) && (*lvec_current < lvec_cnt)) {
+ nr_pages_to_copy = min(nr_pages - nr_pages_copied,
+ max_pages_per_loop);
+
+ rc = process_vm_rw_pages(task, mm, process_pages, pa,
+ start_offset, len,
+ lvec, lvec_cnt,
+ lvec_current, lvec_offset,
+ vm_write, nr_pages_to_copy,
+ &bytes_copied_loop);
+ start_offset = 0;
+ *bytes_copied += bytes_copied_loop;
+
+ if (rc < 0) {
+ return rc;
+ } else {
+ len -= bytes_copied_loop;
+ nr_pages_copied += nr_pages_to_copy;
+ pa += nr_pages_to_copy * PAGE_SIZE;
+ }
+ }
+
+ 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
+ * @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_core(pid_t pid, const struct iovec *lvec,
+ unsigned long liovcnt,
+ 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;
+ ssize_t bytes_copied_loop;
+ ssize_t bytes_copied = 0;
+ unsigned long nr_pages = 0;
+ unsigned long nr_pages_iov;
+ unsigned long iov_l_curr_idx = 0;
+ size_t iov_l_curr_offset = 0;
+ ssize_t iov_len;
+
+ /*
+ * 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 */
+ rcu_read_lock();
+ task = find_task_by_vpid(pid);
+ if (task)
+ get_task_struct(task);
+ rcu_read_unlock();
+ if (!task) {
+ rc = -ESRCH;
+ goto free_proc_pages;
+ }
+
+ task_lock(task);
+ if (__ptrace_may_access(task, PTRACE_MODE_ATTACH)) {
+ task_unlock(task);
+ rc = -EPERM;
+ goto put_task_struct;
+ }
+ mm = task->mm;
+
+ if (!mm || (task->flags & PF_KTHREAD)) {
+ task_unlock(task);
+ rc = -EINVAL;
+ goto put_task_struct;
+ }
+
+ atomic_inc(&mm->mm_users);
+ task_unlock(task);
+
+ for (i = 0; i < riovcnt && iov_l_curr_idx < liovcnt; i++) {
+ rc = process_vm_rw_single_vec(
+ (unsigned long)rvec[i].iov_base, rvec[i].iov_len,
+ lvec, liovcnt, &iov_l_curr_idx, &iov_l_curr_offset,
+ process_pages, mm, task, vm_write, &bytes_copied_loop);
+ bytes_copied += bytes_copied_loop;
+ if (rc != 0) {
+ /* 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 (bytes_copied)
+ rc = bytes_copied;
+ goto put_mm;
+ }
+ }
+
+ rc = bytes_copied;
+put_mm:
+ 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 = iovstack_r;
+ ssize_t rc;
+
+ if (flags != 0)
+ return -EINVAL;
+
+ /* Check iovecs */
+ if (vm_write)
+ rc = rw_copy_check_uvector(WRITE, lvec, liovcnt, UIO_FASTIOV,
+ iovstack_l, &iov_l, 1);
+ else
+ rc = rw_copy_check_uvector(READ, lvec, liovcnt, UIO_FASTIOV,
+ iovstack_l, &iov_l, 1);
+ if (rc <= 0)
+ goto free_iovecs;
+
+ rc = rw_copy_check_uvector(READ, rvec, riovcnt, UIO_FASTIOV,
+ iovstack_r, &iov_r, 0);
+ if (rc <= 0)
+ goto free_iovecs;
+
+ rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
+ vm_write);
+
+free_iovecs:
+ if (iov_r != iovstack_r)
+ kfree(iov_r);
+ if (iov_l != iovstack_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);
+}
+
+#ifdef CONFIG_COMPAT
+
+asmlinkage ssize_t
+compat_process_vm_rw(compat_pid_t pid,
+ const struct compat_iovec __user *lvec,
+ unsigned long liovcnt,
+ const struct compat_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 = iovstack_r;
+ ssize_t rc = -EFAULT;
+
+ if (flags != 0)
+ return -EINVAL;
+
+ if (!access_ok(VERIFY_READ, lvec, liovcnt * sizeof(*lvec)))
+ goto out;
+
+ if (!access_ok(VERIFY_READ, rvec, riovcnt * sizeof(*rvec)))
+ goto out;
+
+ if (vm_write)
+ rc = compat_rw_copy_check_uvector(WRITE, lvec, liovcnt,
+ UIO_FASTIOV, iovstack_l,
+ &iov_l, 1);
+ else
+ rc = compat_rw_copy_check_uvector(READ, lvec, liovcnt,
+ UIO_FASTIOV, iovstack_l,
+ &iov_l, 1);
+ if (rc <= 0)
+ goto free_iovecs;
+ rc = compat_rw_copy_check_uvector(READ, rvec, riovcnt,
+ UIO_FASTIOV, iovstack_r,
+ &iov_r, 0);
+ if (rc <= 0)
+ goto free_iovecs;
+
+ rc = process_vm_rw_core(pid, iov_l, liovcnt, iov_r, riovcnt, flags,
+ vm_write);
+
+free_iovecs:
+ if (iov_r != iovstack_r)
+ kfree(iov_r);
+ if (iov_l != iovstack_l)
+ kfree(iov_l);
+
+out:
+ return rc;
+}
+
+asmlinkage ssize_t
+compat_sys_process_vm_readv(compat_pid_t pid,
+ const struct compat_iovec __user *lvec,
+ unsigned long liovcnt,
+ const struct compat_iovec __user *rvec,
+ unsigned long riovcnt,
+ unsigned long flags)
+{
+ return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+ riovcnt, flags, 0);
+}
+
+asmlinkage ssize_t
+compat_sys_process_vm_writev(compat_pid_t pid,
+ const struct compat_iovec __user *lvec,
+ unsigned long liovcnt,
+ const struct compat_iovec __user *rvec,
+ unsigned long riovcnt,
+ unsigned long flags)
+{
+ return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
+ riovcnt, flags, 1);
+}
+
+#endif
git.openpandora.org / pandora-kernel.git / commitdiff