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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
fcf63409 CY |
2 | /* |
3 | * linux/mm/process_vm_access.c | |
4 | * | |
5 | * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp. | |
fcf63409 CY |
6 | */ |
7 | ||
8 | #include <linux/mm.h> | |
9 | #include <linux/uio.h> | |
10 | #include <linux/sched.h> | |
6e84f315 | 11 | #include <linux/sched/mm.h> |
fcf63409 CY |
12 | #include <linux/highmem.h> |
13 | #include <linux/ptrace.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/syscalls.h> | |
16 | ||
17 | #ifdef CONFIG_COMPAT | |
18 | #include <linux/compat.h> | |
19 | #endif | |
20 | ||
21 | /** | |
22 | * process_vm_rw_pages - read/write pages from task specified | |
4bafbec7 | 23 | * @pages: array of pointers to pages we want to copy |
f144c390 | 24 | * @offset: offset in page to start copying from/to |
fcf63409 | 25 | * @len: number of bytes to copy |
4bafbec7 | 26 | * @iter: where to copy to/from locally |
fcf63409 | 27 | * @vm_write: 0 means copy from, 1 means copy to |
fcf63409 CY |
28 | * Returns 0 on success, error code otherwise |
29 | */ | |
70eca12d AV |
30 | static int process_vm_rw_pages(struct page **pages, |
31 | unsigned offset, | |
e21345f9 | 32 | size_t len, |
9f78bdfa | 33 | struct iov_iter *iter, |
9acc1a0f | 34 | int vm_write) |
fcf63409 | 35 | { |
fcf63409 | 36 | /* Do the copy for each page */ |
9acc1a0f | 37 | while (len && iov_iter_count(iter)) { |
70eca12d | 38 | struct page *page = *pages++; |
e21345f9 | 39 | size_t copy = PAGE_SIZE - offset; |
70eca12d | 40 | size_t copied; |
240f3905 | 41 | |
e21345f9 AV |
42 | if (copy > len) |
43 | copy = len; | |
44 | ||
803e4572 | 45 | if (vm_write) |
e7c24607 | 46 | copied = copy_page_from_iter(page, offset, copy, iter); |
803e4572 | 47 | else |
70eca12d | 48 | copied = copy_page_to_iter(page, offset, copy, iter); |
803e4572 | 49 | |
70eca12d AV |
50 | len -= copied; |
51 | if (copied < copy && iov_iter_count(iter)) | |
52 | return -EFAULT; | |
53 | offset = 0; | |
fcf63409 | 54 | } |
70eca12d | 55 | return 0; |
fcf63409 CY |
56 | } |
57 | ||
58 | /* Maximum number of pages kmalloc'd to hold struct page's during copy */ | |
59 | #define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2) | |
60 | ||
61 | /** | |
62 | * process_vm_rw_single_vec - read/write pages from task specified | |
63 | * @addr: start memory address of target process | |
64 | * @len: size of area to copy to/from | |
4bafbec7 | 65 | * @iter: where to copy to/from locally |
fcf63409 CY |
66 | * @process_pages: struct pages area that can store at least |
67 | * nr_pages_to_copy struct page pointers | |
68 | * @mm: mm for task | |
69 | * @task: task to read/write from | |
70 | * @vm_write: 0 means copy from, 1 means copy to | |
fcf63409 CY |
71 | * Returns 0 on success or on failure error code |
72 | */ | |
73 | static int process_vm_rw_single_vec(unsigned long addr, | |
74 | unsigned long len, | |
9f78bdfa | 75 | struct iov_iter *iter, |
fcf63409 CY |
76 | struct page **process_pages, |
77 | struct mm_struct *mm, | |
78 | struct task_struct *task, | |
9acc1a0f | 79 | int vm_write) |
fcf63409 CY |
80 | { |
81 | unsigned long pa = addr & PAGE_MASK; | |
82 | unsigned long start_offset = addr - pa; | |
83 | unsigned long nr_pages; | |
fcf63409 | 84 | ssize_t rc = 0; |
fcf63409 CY |
85 | unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES |
86 | / sizeof(struct pages *); | |
8b7457ef | 87 | unsigned int flags = 0; |
fcf63409 | 88 | |
fcf63409 CY |
89 | /* Work out address and page range required */ |
90 | if (len == 0) | |
91 | return 0; | |
92 | nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1; | |
93 | ||
d4944b0e LS |
94 | if (vm_write) |
95 | flags |= FOLL_WRITE; | |
96 | ||
4bafbec7 | 97 | while (!rc && nr_pages && iov_iter_count(iter)) { |
803e4572 | 98 | int pinned_pages = min(nr_pages, max_pages_per_loop); |
8b7457ef | 99 | int locked = 1; |
4bafbec7 | 100 | size_t bytes; |
fcf63409 | 101 | |
1e987790 DH |
102 | /* |
103 | * Get the pages we're interested in. We must | |
8b7457ef | 104 | * access remotely because task/mm might not |
1e987790 DH |
105 | * current/current->mm |
106 | */ | |
d8ed45c5 | 107 | mmap_read_lock(mm); |
803e4572 JH |
108 | pinned_pages = pin_user_pages_remote(task, mm, pa, pinned_pages, |
109 | flags, process_pages, | |
110 | NULL, &locked); | |
8b7457ef | 111 | if (locked) |
d8ed45c5 | 112 | mmap_read_unlock(mm); |
803e4572 | 113 | if (pinned_pages <= 0) |
70eca12d AV |
114 | return -EFAULT; |
115 | ||
803e4572 | 116 | bytes = pinned_pages * PAGE_SIZE - start_offset; |
4bafbec7 AV |
117 | if (bytes > len) |
118 | bytes = len; | |
e21345f9 | 119 | |
70eca12d | 120 | rc = process_vm_rw_pages(process_pages, |
4bafbec7 | 121 | start_offset, bytes, iter, |
9acc1a0f | 122 | vm_write); |
4bafbec7 | 123 | len -= bytes; |
fcf63409 | 124 | start_offset = 0; |
803e4572 JH |
125 | nr_pages -= pinned_pages; |
126 | pa += pinned_pages * PAGE_SIZE; | |
127 | ||
128 | /* If vm_write is set, the pages need to be made dirty: */ | |
f1f6a7dd JH |
129 | unpin_user_pages_dirty_lock(process_pages, pinned_pages, |
130 | vm_write); | |
fcf63409 CY |
131 | } |
132 | ||
133 | return rc; | |
134 | } | |
135 | ||
136 | /* Maximum number of entries for process pages array | |
137 | which lives on stack */ | |
138 | #define PVM_MAX_PP_ARRAY_COUNT 16 | |
139 | ||
140 | /** | |
141 | * process_vm_rw_core - core of reading/writing pages from task specified | |
142 | * @pid: PID of process to read/write from/to | |
4bafbec7 | 143 | * @iter: where to copy to/from locally |
fcf63409 CY |
144 | * @rvec: iovec array specifying where to copy to/from in the other process |
145 | * @riovcnt: size of rvec array | |
146 | * @flags: currently unused | |
147 | * @vm_write: 0 if reading from other process, 1 if writing to other process | |
a5d09bed | 148 | * |
fcf63409 CY |
149 | * Returns the number of bytes read/written or error code. May |
150 | * return less bytes than expected if an error occurs during the copying | |
151 | * process. | |
152 | */ | |
9f78bdfa | 153 | static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, |
fcf63409 CY |
154 | const struct iovec *rvec, |
155 | unsigned long riovcnt, | |
156 | unsigned long flags, int vm_write) | |
157 | { | |
158 | struct task_struct *task; | |
159 | struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; | |
160 | struct page **process_pages = pp_stack; | |
161 | struct mm_struct *mm; | |
162 | unsigned long i; | |
163 | ssize_t rc = 0; | |
fcf63409 CY |
164 | unsigned long nr_pages = 0; |
165 | unsigned long nr_pages_iov; | |
fcf63409 | 166 | ssize_t iov_len; |
9acc1a0f | 167 | size_t total_len = iov_iter_count(iter); |
fcf63409 CY |
168 | |
169 | /* | |
170 | * Work out how many pages of struct pages we're going to need | |
171 | * when eventually calling get_user_pages | |
172 | */ | |
173 | for (i = 0; i < riovcnt; i++) { | |
174 | iov_len = rvec[i].iov_len; | |
175 | if (iov_len > 0) { | |
176 | nr_pages_iov = ((unsigned long)rvec[i].iov_base | |
177 | + iov_len) | |
178 | / PAGE_SIZE - (unsigned long)rvec[i].iov_base | |
179 | / PAGE_SIZE + 1; | |
180 | nr_pages = max(nr_pages, nr_pages_iov); | |
181 | } | |
182 | } | |
183 | ||
184 | if (nr_pages == 0) | |
185 | return 0; | |
186 | ||
187 | if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { | |
188 | /* For reliability don't try to kmalloc more than | |
189 | 2 pages worth */ | |
190 | process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES, | |
191 | sizeof(struct pages *)*nr_pages), | |
192 | GFP_KERNEL); | |
193 | ||
194 | if (!process_pages) | |
195 | return -ENOMEM; | |
196 | } | |
197 | ||
198 | /* Get process information */ | |
2ee08260 | 199 | task = find_get_task_by_vpid(pid); |
fcf63409 CY |
200 | if (!task) { |
201 | rc = -ESRCH; | |
202 | goto free_proc_pages; | |
203 | } | |
204 | ||
caaee623 | 205 | mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS); |
8cdb878d CY |
206 | if (!mm || IS_ERR(mm)) { |
207 | rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; | |
208 | /* | |
8d09db80 | 209 | * Explicitly map EACCES to EPERM as EPERM is a more |
8cdb878d CY |
210 | * appropriate error code for process_vw_readv/writev |
211 | */ | |
212 | if (rc == -EACCES) | |
213 | rc = -EPERM; | |
fcf63409 CY |
214 | goto put_task_struct; |
215 | } | |
216 | ||
9acc1a0f | 217 | for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++) |
fcf63409 CY |
218 | rc = process_vm_rw_single_vec( |
219 | (unsigned long)rvec[i].iov_base, rvec[i].iov_len, | |
9acc1a0f AV |
220 | iter, process_pages, mm, task, vm_write); |
221 | ||
222 | /* copied = space before - space after */ | |
223 | total_len -= iov_iter_count(iter); | |
224 | ||
225 | /* If we have managed to copy any data at all then | |
226 | we return the number of bytes copied. Otherwise | |
227 | we return the error code */ | |
228 | if (total_len) | |
229 | rc = total_len; | |
fcf63409 | 230 | |
fcf63409 CY |
231 | mmput(mm); |
232 | ||
233 | put_task_struct: | |
234 | put_task_struct(task); | |
235 | ||
236 | free_proc_pages: | |
237 | if (process_pages != pp_stack) | |
238 | kfree(process_pages); | |
239 | return rc; | |
240 | } | |
241 | ||
242 | /** | |
243 | * process_vm_rw - check iovecs before calling core routine | |
244 | * @pid: PID of process to read/write from/to | |
245 | * @lvec: iovec array specifying where to copy to/from locally | |
246 | * @liovcnt: size of lvec array | |
247 | * @rvec: iovec array specifying where to copy to/from in the other process | |
248 | * @riovcnt: size of rvec array | |
249 | * @flags: currently unused | |
250 | * @vm_write: 0 if reading from other process, 1 if writing to other process | |
a5d09bed | 251 | * |
fcf63409 CY |
252 | * Returns the number of bytes read/written or error code. May |
253 | * return less bytes than expected if an error occurs during the copying | |
254 | * process. | |
255 | */ | |
256 | static ssize_t process_vm_rw(pid_t pid, | |
257 | const struct iovec __user *lvec, | |
258 | unsigned long liovcnt, | |
259 | const struct iovec __user *rvec, | |
260 | unsigned long riovcnt, | |
261 | unsigned long flags, int vm_write) | |
262 | { | |
263 | struct iovec iovstack_l[UIO_FASTIOV]; | |
264 | struct iovec iovstack_r[UIO_FASTIOV]; | |
265 | struct iovec *iov_l = iovstack_l; | |
266 | struct iovec *iov_r = iovstack_r; | |
9f78bdfa | 267 | struct iov_iter iter; |
fcf63409 | 268 | ssize_t rc; |
17d17e72 | 269 | int dir = vm_write ? WRITE : READ; |
fcf63409 CY |
270 | |
271 | if (flags != 0) | |
272 | return -EINVAL; | |
273 | ||
274 | /* Check iovecs */ | |
17d17e72 AV |
275 | rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); |
276 | if (rc < 0) | |
277 | return rc; | |
278 | if (!iov_iter_count(&iter)) | |
fcf63409 CY |
279 | goto free_iovecs; |
280 | ||
ac34ebb3 CY |
281 | rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV, |
282 | iovstack_r, &iov_r); | |
fcf63409 CY |
283 | if (rc <= 0) |
284 | goto free_iovecs; | |
285 | ||
9f78bdfa | 286 | rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf63409 CY |
287 | |
288 | free_iovecs: | |
289 | if (iov_r != iovstack_r) | |
290 | kfree(iov_r); | |
17d17e72 | 291 | kfree(iov_l); |
fcf63409 CY |
292 | |
293 | return rc; | |
294 | } | |
295 | ||
296 | SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, | |
297 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
298 | unsigned long, riovcnt, unsigned long, flags) | |
299 | { | |
300 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); | |
301 | } | |
302 | ||
303 | SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, | |
304 | const struct iovec __user *, lvec, | |
305 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
306 | unsigned long, riovcnt, unsigned long, flags) | |
307 | { | |
308 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); | |
309 | } | |
310 | ||
311 | #ifdef CONFIG_COMPAT | |
312 | ||
2eb2e141 | 313 | static ssize_t |
fcf63409 CY |
314 | compat_process_vm_rw(compat_pid_t pid, |
315 | const struct compat_iovec __user *lvec, | |
316 | unsigned long liovcnt, | |
317 | const struct compat_iovec __user *rvec, | |
318 | unsigned long riovcnt, | |
319 | unsigned long flags, int vm_write) | |
320 | { | |
321 | struct iovec iovstack_l[UIO_FASTIOV]; | |
322 | struct iovec iovstack_r[UIO_FASTIOV]; | |
323 | struct iovec *iov_l = iovstack_l; | |
324 | struct iovec *iov_r = iovstack_r; | |
9f78bdfa | 325 | struct iov_iter iter; |
fcf63409 | 326 | ssize_t rc = -EFAULT; |
17d17e72 | 327 | int dir = vm_write ? WRITE : READ; |
fcf63409 CY |
328 | |
329 | if (flags != 0) | |
330 | return -EINVAL; | |
331 | ||
17d17e72 AV |
332 | rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); |
333 | if (rc < 0) | |
334 | return rc; | |
335 | if (!iov_iter_count(&iter)) | |
fcf63409 | 336 | goto free_iovecs; |
ac34ebb3 | 337 | rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, |
fcf63409 | 338 | UIO_FASTIOV, iovstack_r, |
ac34ebb3 | 339 | &iov_r); |
fcf63409 CY |
340 | if (rc <= 0) |
341 | goto free_iovecs; | |
342 | ||
9f78bdfa | 343 | rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf63409 CY |
344 | |
345 | free_iovecs: | |
346 | if (iov_r != iovstack_r) | |
347 | kfree(iov_r); | |
17d17e72 | 348 | kfree(iov_l); |
fcf63409 CY |
349 | return rc; |
350 | } | |
351 | ||
2f2728f6 HC |
352 | COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid, |
353 | const struct compat_iovec __user *, lvec, | |
354 | compat_ulong_t, liovcnt, | |
355 | const struct compat_iovec __user *, rvec, | |
356 | compat_ulong_t, riovcnt, | |
357 | compat_ulong_t, flags) | |
fcf63409 CY |
358 | { |
359 | return compat_process_vm_rw(pid, lvec, liovcnt, rvec, | |
360 | riovcnt, flags, 0); | |
361 | } | |
362 | ||
2f2728f6 HC |
363 | COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid, |
364 | const struct compat_iovec __user *, lvec, | |
365 | compat_ulong_t, liovcnt, | |
366 | const struct compat_iovec __user *, rvec, | |
367 | compat_ulong_t, riovcnt, | |
368 | compat_ulong_t, flags) | |
fcf63409 CY |
369 | { |
370 | return compat_process_vm_rw(pid, lvec, liovcnt, rvec, | |
371 | riovcnt, flags, 1); | |
372 | } | |
373 | ||
374 | #endif |