Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek...
[GitHub/LineageOS/android_kernel_motorola_exynos9610.git] / mm / process_vm_access.c
1 /*
2 * linux/mm/process_vm_access.c
3 *
4 * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp.
5 *
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.
10 */
11
12 #include <linux/mm.h>
13 #include <linux/uio.h>
14 #include <linux/sched.h>
15 #include <linux/sched/mm.h>
16 #include <linux/highmem.h>
17 #include <linux/ptrace.h>
18 #include <linux/slab.h>
19 #include <linux/syscalls.h>
20
21 #ifdef CONFIG_COMPAT
22 #include <linux/compat.h>
23 #endif
24
25 /**
26 * process_vm_rw_pages - read/write pages from task specified
27 * @pages: array of pointers to pages we want to copy
28 * @start_offset: offset in page to start copying from/to
29 * @len: number of bytes to copy
30 * @iter: where to copy to/from locally
31 * @vm_write: 0 means copy from, 1 means copy to
32 * Returns 0 on success, error code otherwise
33 */
34 static int process_vm_rw_pages(struct page **pages,
35 unsigned offset,
36 size_t len,
37 struct iov_iter *iter,
38 int vm_write)
39 {
40 /* Do the copy for each page */
41 while (len && iov_iter_count(iter)) {
42 struct page *page = *pages++;
43 size_t copy = PAGE_SIZE - offset;
44 size_t copied;
45
46 if (copy > len)
47 copy = len;
48
49 if (vm_write) {
50 copied = copy_page_from_iter(page, offset, copy, iter);
51 set_page_dirty_lock(page);
52 } else {
53 copied = copy_page_to_iter(page, offset, copy, iter);
54 }
55 len -= copied;
56 if (copied < copy && iov_iter_count(iter))
57 return -EFAULT;
58 offset = 0;
59 }
60 return 0;
61 }
62
63 /* Maximum number of pages kmalloc'd to hold struct page's during copy */
64 #define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2)
65
66 /**
67 * process_vm_rw_single_vec - read/write pages from task specified
68 * @addr: start memory address of target process
69 * @len: size of area to copy to/from
70 * @iter: where to copy to/from locally
71 * @process_pages: struct pages area that can store at least
72 * nr_pages_to_copy struct page pointers
73 * @mm: mm for task
74 * @task: task to read/write from
75 * @vm_write: 0 means copy from, 1 means copy to
76 * Returns 0 on success or on failure error code
77 */
78 static int process_vm_rw_single_vec(unsigned long addr,
79 unsigned long len,
80 struct iov_iter *iter,
81 struct page **process_pages,
82 struct mm_struct *mm,
83 struct task_struct *task,
84 int vm_write)
85 {
86 unsigned long pa = addr & PAGE_MASK;
87 unsigned long start_offset = addr - pa;
88 unsigned long nr_pages;
89 ssize_t rc = 0;
90 unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
91 / sizeof(struct pages *);
92 unsigned int flags = 0;
93
94 /* Work out address and page range required */
95 if (len == 0)
96 return 0;
97 nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
98
99 if (vm_write)
100 flags |= FOLL_WRITE;
101
102 while (!rc && nr_pages && iov_iter_count(iter)) {
103 int pages = min(nr_pages, max_pages_per_loop);
104 int locked = 1;
105 size_t bytes;
106
107 /*
108 * Get the pages we're interested in. We must
109 * access remotely because task/mm might not
110 * current/current->mm
111 */
112 down_read(&mm->mmap_sem);
113 pages = get_user_pages_remote(task, mm, pa, pages, flags,
114 process_pages, NULL, &locked);
115 if (locked)
116 up_read(&mm->mmap_sem);
117 if (pages <= 0)
118 return -EFAULT;
119
120 bytes = pages * PAGE_SIZE - start_offset;
121 if (bytes > len)
122 bytes = len;
123
124 rc = process_vm_rw_pages(process_pages,
125 start_offset, bytes, iter,
126 vm_write);
127 len -= bytes;
128 start_offset = 0;
129 nr_pages -= pages;
130 pa += pages * PAGE_SIZE;
131 while (pages)
132 put_page(process_pages[--pages]);
133 }
134
135 return rc;
136 }
137
138 /* Maximum number of entries for process pages array
139 which lives on stack */
140 #define PVM_MAX_PP_ARRAY_COUNT 16
141
142 /**
143 * process_vm_rw_core - core of reading/writing pages from task specified
144 * @pid: PID of process to read/write from/to
145 * @iter: where to copy to/from locally
146 * @rvec: iovec array specifying where to copy to/from in the other process
147 * @riovcnt: size of rvec array
148 * @flags: currently unused
149 * @vm_write: 0 if reading from other process, 1 if writing to other process
150 * Returns the number of bytes read/written or error code. May
151 * return less bytes than expected if an error occurs during the copying
152 * process.
153 */
154 static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
155 const struct iovec *rvec,
156 unsigned long riovcnt,
157 unsigned long flags, int vm_write)
158 {
159 struct task_struct *task;
160 struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT];
161 struct page **process_pages = pp_stack;
162 struct mm_struct *mm;
163 unsigned long i;
164 ssize_t rc = 0;
165 unsigned long nr_pages = 0;
166 unsigned long nr_pages_iov;
167 ssize_t iov_len;
168 size_t total_len = iov_iter_count(iter);
169
170 /*
171 * Work out how many pages of struct pages we're going to need
172 * when eventually calling get_user_pages
173 */
174 for (i = 0; i < riovcnt; i++) {
175 iov_len = rvec[i].iov_len;
176 if (iov_len > 0) {
177 nr_pages_iov = ((unsigned long)rvec[i].iov_base
178 + iov_len)
179 / PAGE_SIZE - (unsigned long)rvec[i].iov_base
180 / PAGE_SIZE + 1;
181 nr_pages = max(nr_pages, nr_pages_iov);
182 }
183 }
184
185 if (nr_pages == 0)
186 return 0;
187
188 if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) {
189 /* For reliability don't try to kmalloc more than
190 2 pages worth */
191 process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES,
192 sizeof(struct pages *)*nr_pages),
193 GFP_KERNEL);
194
195 if (!process_pages)
196 return -ENOMEM;
197 }
198
199 /* Get process information */
200 rcu_read_lock();
201 task = find_task_by_vpid(pid);
202 if (task)
203 get_task_struct(task);
204 rcu_read_unlock();
205 if (!task) {
206 rc = -ESRCH;
207 goto free_proc_pages;
208 }
209
210 mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS);
211 if (!mm || IS_ERR(mm)) {
212 rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
213 /*
214 * Explicitly map EACCES to EPERM as EPERM is a more a
215 * appropriate error code for process_vw_readv/writev
216 */
217 if (rc == -EACCES)
218 rc = -EPERM;
219 goto put_task_struct;
220 }
221
222 for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++)
223 rc = process_vm_rw_single_vec(
224 (unsigned long)rvec[i].iov_base, rvec[i].iov_len,
225 iter, process_pages, mm, task, vm_write);
226
227 /* copied = space before - space after */
228 total_len -= iov_iter_count(iter);
229
230 /* If we have managed to copy any data at all then
231 we return the number of bytes copied. Otherwise
232 we return the error code */
233 if (total_len)
234 rc = total_len;
235
236 mmput(mm);
237
238 put_task_struct:
239 put_task_struct(task);
240
241 free_proc_pages:
242 if (process_pages != pp_stack)
243 kfree(process_pages);
244 return rc;
245 }
246
247 /**
248 * process_vm_rw - check iovecs before calling core routine
249 * @pid: PID of process to read/write from/to
250 * @lvec: iovec array specifying where to copy to/from locally
251 * @liovcnt: size of lvec array
252 * @rvec: iovec array specifying where to copy to/from in the other process
253 * @riovcnt: size of rvec array
254 * @flags: currently unused
255 * @vm_write: 0 if reading from other process, 1 if writing to other process
256 * Returns the number of bytes read/written or error code. May
257 * return less bytes than expected if an error occurs during the copying
258 * process.
259 */
260 static ssize_t process_vm_rw(pid_t pid,
261 const struct iovec __user *lvec,
262 unsigned long liovcnt,
263 const struct iovec __user *rvec,
264 unsigned long riovcnt,
265 unsigned long flags, int vm_write)
266 {
267 struct iovec iovstack_l[UIO_FASTIOV];
268 struct iovec iovstack_r[UIO_FASTIOV];
269 struct iovec *iov_l = iovstack_l;
270 struct iovec *iov_r = iovstack_r;
271 struct iov_iter iter;
272 ssize_t rc;
273 int dir = vm_write ? WRITE : READ;
274
275 if (flags != 0)
276 return -EINVAL;
277
278 /* Check iovecs */
279 rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
280 if (rc < 0)
281 return rc;
282 if (!iov_iter_count(&iter))
283 goto free_iovecs;
284
285 rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
286 iovstack_r, &iov_r);
287 if (rc <= 0)
288 goto free_iovecs;
289
290 rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
291
292 free_iovecs:
293 if (iov_r != iovstack_r)
294 kfree(iov_r);
295 kfree(iov_l);
296
297 return rc;
298 }
299
300 SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec,
301 unsigned long, liovcnt, const struct iovec __user *, rvec,
302 unsigned long, riovcnt, unsigned long, flags)
303 {
304 return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0);
305 }
306
307 SYSCALL_DEFINE6(process_vm_writev, pid_t, pid,
308 const struct iovec __user *, lvec,
309 unsigned long, liovcnt, const struct iovec __user *, rvec,
310 unsigned long, riovcnt, unsigned long, flags)
311 {
312 return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1);
313 }
314
315 #ifdef CONFIG_COMPAT
316
317 static ssize_t
318 compat_process_vm_rw(compat_pid_t pid,
319 const struct compat_iovec __user *lvec,
320 unsigned long liovcnt,
321 const struct compat_iovec __user *rvec,
322 unsigned long riovcnt,
323 unsigned long flags, int vm_write)
324 {
325 struct iovec iovstack_l[UIO_FASTIOV];
326 struct iovec iovstack_r[UIO_FASTIOV];
327 struct iovec *iov_l = iovstack_l;
328 struct iovec *iov_r = iovstack_r;
329 struct iov_iter iter;
330 ssize_t rc = -EFAULT;
331 int dir = vm_write ? WRITE : READ;
332
333 if (flags != 0)
334 return -EINVAL;
335
336 rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter);
337 if (rc < 0)
338 return rc;
339 if (!iov_iter_count(&iter))
340 goto free_iovecs;
341 rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt,
342 UIO_FASTIOV, iovstack_r,
343 &iov_r);
344 if (rc <= 0)
345 goto free_iovecs;
346
347 rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write);
348
349 free_iovecs:
350 if (iov_r != iovstack_r)
351 kfree(iov_r);
352 kfree(iov_l);
353 return rc;
354 }
355
356 COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid,
357 const struct compat_iovec __user *, lvec,
358 compat_ulong_t, liovcnt,
359 const struct compat_iovec __user *, rvec,
360 compat_ulong_t, riovcnt,
361 compat_ulong_t, flags)
362 {
363 return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
364 riovcnt, flags, 0);
365 }
366
367 COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid,
368 const struct compat_iovec __user *, lvec,
369 compat_ulong_t, liovcnt,
370 const struct compat_iovec __user *, rvec,
371 compat_ulong_t, riovcnt,
372 compat_ulong_t, flags)
373 {
374 return compat_process_vm_rw(pid, lvec, liovcnt, rvec,
375 riovcnt, flags, 1);
376 }
377
378 #endif