memcg: export struct mem_cgroup
[linux/fpc-iii.git] / mm / process_vm_access.c
blobe88d071648c2dece38b25d3fc8e57091d1fcd1d1
1 /*
2 * linux/mm/process_vm_access.c
4 * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 #include <linux/mm.h>
13 #include <linux/uio.h>
14 #include <linux/sched.h>
15 #include <linux/highmem.h>
16 #include <linux/ptrace.h>
17 #include <linux/slab.h>
18 #include <linux/syscalls.h>
20 #ifdef CONFIG_COMPAT
21 #include <linux/compat.h>
22 #endif
24 /**
25 * process_vm_rw_pages - read/write pages from task specified
26 * @pages: array of pointers to pages we want to copy
27 * @start_offset: offset in page to start copying from/to
28 * @len: number of bytes to copy
29 * @iter: where to copy to/from locally
30 * @vm_write: 0 means copy from, 1 means copy to
31 * Returns 0 on success, error code otherwise
33 static int process_vm_rw_pages(struct page **pages,
34 unsigned offset,
35 size_t len,
36 struct iov_iter *iter,
37 int vm_write)
39 /* Do the copy for each page */
40 while (len && iov_iter_count(iter)) {
41 struct page *page = *pages++;
42 size_t copy = PAGE_SIZE - offset;
43 size_t copied;
45 if (copy > len)
46 copy = len;
48 if (vm_write) {
49 copied = copy_page_from_iter(page, offset, copy, iter);
50 set_page_dirty_lock(page);
51 } else {
52 copied = copy_page_to_iter(page, offset, copy, iter);
54 len -= copied;
55 if (copied < copy && iov_iter_count(iter))
56 return -EFAULT;
57 offset = 0;
59 return 0;
62 /* Maximum number of pages kmalloc'd to hold struct page's during copy */
63 #define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
65 /**
66 * process_vm_rw_single_vec - read/write pages from task specified
67 * @addr: start memory address of target process
68 * @len: size of area to copy to/from
69 * @iter: where to copy to/from locally
70 * @process_pages: struct pages area that can store at least
71 * nr_pages_to_copy struct page pointers
72 * @mm: mm for task
73 * @task: task to read/write from
74 * @vm_write: 0 means copy from, 1 means copy to
75 * Returns 0 on success or on failure error code
77 static int process_vm_rw_single_vec(unsigned long addr,
78 unsigned long len,
79 struct iov_iter *iter,
80 struct page **process_pages,
81 struct mm_struct *mm,
82 struct task_struct *task,
83 int vm_write)
85 unsigned long pa = addr & PAGE_MASK;
86 unsigned long start_offset = addr - pa;
87 unsigned long nr_pages;
88 ssize_t rc = 0;
89 unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
90 / sizeof(struct pages *);
92 /* Work out address and page range required */
93 if (len == 0)
94 return 0;
95 nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
97 while (!rc && nr_pages && iov_iter_count(iter)) {
98 int pages = min(nr_pages, max_pages_per_loop);
99 size_t bytes;
101 /* Get the pages we're interested in */
102 pages = get_user_pages_unlocked(task, mm, pa, pages,
103 vm_write, 0, process_pages);
104 if (pages <= 0)
105 return -EFAULT;
107 bytes = pages * PAGE_SIZE - start_offset;
108 if (bytes > len)
109 bytes = len;
111 rc = process_vm_rw_pages(process_pages,
112 start_offset, bytes, iter,
113 vm_write);
114 len -= bytes;
115 start_offset = 0;
116 nr_pages -= pages;
117 pa += pages * PAGE_SIZE;
118 while (pages)
119 put_page(process_pages[--pages]);
122 return rc;
125 /* Maximum number of entries for process pages array
126 which lives on stack */
127 #define PVM_MAX_PP_ARRAY_COUNT 16
130 * process_vm_rw_core - core of reading/writing pages from task specified
131 * @pid: PID of process to read/write from/to
132 * @iter: where to copy to/from locally
133 * @rvec: iovec array specifying where to copy to/from in the other process
134 * @riovcnt: size of rvec array
135 * @flags: currently unused
136 * @vm_write: 0 if reading from other process, 1 if writing to other process
137 * Returns the number of bytes read/written or error code. May
138 * return less bytes than expected if an error occurs during the copying
139 * process.
141 static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
142 const struct iovec *rvec,
143 unsigned long riovcnt,
144 unsigned long flags, int vm_write)
146 struct task_struct *task;
147 struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
148 struct page **process_pages = pp_stack;
149 struct mm_struct *mm;
150 unsigned long i;
151 ssize_t rc = 0;
152 unsigned long nr_pages = 0;
153 unsigned long nr_pages_iov;
154 ssize_t iov_len;
155 size_t total_len = iov_iter_count(iter);
158 * Work out how many pages of struct pages we're going to need
159 * when eventually calling get_user_pages
161 for (i = 0; i < riovcnt; i++) {
162 iov_len = rvec[i].iov_len;
163 if (iov_len > 0) {
164 nr_pages_iov = ((unsigned long)rvec[i].iov_base
165 + iov_len)
166 / PAGE_SIZE - (unsigned long)rvec[i].iov_base
167 / PAGE_SIZE + 1;
168 nr_pages = max(nr_pages, nr_pages_iov);
172 if (nr_pages == 0)
173 return 0;
175 if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
176 /* For reliability don't try to kmalloc more than
177 2 pages worth */
178 process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
179 sizeof(struct pages *)*nr_pages),
180 GFP_KERNEL);
182 if (!process_pages)
183 return -ENOMEM;
186 /* Get process information */
187 rcu_read_lock();
188 task = find_task_by_vpid(pid);
189 if (task)
190 get_task_struct(task);
191 rcu_read_unlock();
192 if (!task) {
193 rc = -ESRCH;
194 goto free_proc_pages;
197 mm = mm_access(task, PTRACE_MODE_ATTACH);
198 if (!mm || IS_ERR(mm)) {
199 rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
201 * Explicitly map EACCES to EPERM as EPERM is a more a
202 * appropriate error code for process_vw_readv/writev
204 if (rc == -EACCES)
205 rc = -EPERM;
206 goto put_task_struct;
209 for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
210 rc = process_vm_rw_single_vec(
211 (unsigned long)rvec[i].iov_base, rvec[i].iov_len,
212 iter, process_pages, mm, task, vm_write);
214 /* copied = space before - space after */
215 total_len -= iov_iter_count(iter);
217 /* If we have managed to copy any data at all then
218 we return the number of bytes copied. Otherwise
219 we return the error code */
220 if (total_len)
221 rc = total_len;
223 mmput(mm);
225 put_task_struct:
226 put_task_struct(task);
228 free_proc_pages:
229 if (process_pages != pp_stack)
230 kfree(process_pages);
231 return rc;
235 * process_vm_rw - check iovecs before calling core routine
236 * @pid: PID of process to read/write from/to
237 * @lvec: iovec array specifying where to copy to/from locally
238 * @liovcnt: size of lvec array
239 * @rvec: iovec array specifying where to copy to/from in the other process
240 * @riovcnt: size of rvec array
241 * @flags: currently unused
242 * @vm_write: 0 if reading from other process, 1 if writing to other process
243 * Returns the number of bytes read/written or error code. May
244 * return less bytes than expected if an error occurs during the copying
245 * process.
247 static ssize_t process_vm_rw(pid_t pid,
248 const struct iovec __user *lvec,
249 unsigned long liovcnt,
250 const struct iovec __user *rvec,
251 unsigned long riovcnt,
252 unsigned long flags, int vm_write)
254 struct iovec iovstack_l[UIO_FASTIOV];
255 struct iovec iovstack_r[UIO_FASTIOV];
256 struct iovec *iov_l = iovstack_l;
257 struct iovec *iov_r = iovstack_r;
258 struct iov_iter iter;
259 ssize_t rc;
260 int dir = vm_write ? WRITE : READ;
262 if (flags != 0)
263 return -EINVAL;
265 /* Check iovecs */
266 rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
267 if (rc < 0)
268 return rc;
269 if (!iov_iter_count(&iter))
270 goto free_iovecs;
272 rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
273 iovstack_r, &iov_r);
274 if (rc <= 0)
275 goto free_iovecs;
277 rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
279 free_iovecs:
280 if (iov_r != iovstack_r)
281 kfree(iov_r);
282 kfree(iov_l);
284 return rc;
287 SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
288 unsigned long, liovcnt, const struct iovec __user *, rvec,
289 unsigned long, riovcnt, unsigned long, flags)
291 return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
294 SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
295 const struct iovec __user *, lvec,
296 unsigned long, liovcnt, const struct iovec __user *, rvec,
297 unsigned long, riovcnt, unsigned long, flags)
299 return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
302 #ifdef CONFIG_COMPAT
304 static ssize_t
305 compat_process_vm_rw(compat_pid_t pid,
306 const struct compat_iovec __user *lvec,
307 unsigned long liovcnt,
308 const struct compat_iovec __user *rvec,
309 unsigned long riovcnt,
310 unsigned long flags, int vm_write)
312 struct iovec iovstack_l[UIO_FASTIOV];
313 struct iovec iovstack_r[UIO_FASTIOV];
314 struct iovec *iov_l = iovstack_l;
315 struct iovec *iov_r = iovstack_r;
316 struct iov_iter iter;
317 ssize_t rc = -EFAULT;
318 int dir = vm_write ? WRITE : READ;
320 if (flags != 0)
321 return -EINVAL;
323 rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
324 if (rc < 0)
325 return rc;
326 if (!iov_iter_count(&iter))
327 goto free_iovecs;
328 rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
329 UIO_FASTIOV, iovstack_r,
330 &iov_r);
331 if (rc <= 0)
332 goto free_iovecs;
334 rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
336 free_iovecs:
337 if (iov_r != iovstack_r)
338 kfree(iov_r);
339 kfree(iov_l);
340 return rc;
343 COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
344 const struct compat_iovec __user *, lvec,
345 compat_ulong_t, liovcnt,
346 const struct compat_iovec __user *, rvec,
347 compat_ulong_t, riovcnt,
348 compat_ulong_t, flags)
350 return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
351 riovcnt, flags, 0);
354 COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
355 const struct compat_iovec __user *, lvec,
356 compat_ulong_t, liovcnt,
357 const struct compat_iovec __user *, rvec,
358 compat_ulong_t, riovcnt,
359 compat_ulong_t, flags)
361 return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
362 riovcnt, flags, 1);
365 #endif