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