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fcf63409 CY |
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> | |
6e84f315 | 15 | #include <linux/sched/mm.h> |
fcf63409 CY |
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 | |
4bafbec7 | 27 | * @pages: array of pointers to pages we want to copy |
f144c390 | 28 | * @offset: offset in page to start copying from/to |
fcf63409 | 29 | * @len: number of bytes to copy |
4bafbec7 | 30 | * @iter: where to copy to/from locally |
fcf63409 | 31 | * @vm_write: 0 means copy from, 1 means copy to |
fcf63409 CY |
32 | * Returns 0 on success, error code otherwise |
33 | */ | |
70eca12d AV |
34 | static int process_vm_rw_pages(struct page **pages, |
35 | unsigned offset, | |
e21345f9 | 36 | size_t len, |
9f78bdfa | 37 | struct iov_iter *iter, |
9acc1a0f | 38 | int vm_write) |
fcf63409 | 39 | { |
fcf63409 | 40 | /* Do the copy for each page */ |
9acc1a0f | 41 | while (len && iov_iter_count(iter)) { |
70eca12d | 42 | struct page *page = *pages++; |
e21345f9 | 43 | size_t copy = PAGE_SIZE - offset; |
70eca12d | 44 | size_t copied; |
240f3905 | 45 | |
e21345f9 AV |
46 | if (copy > len) |
47 | copy = len; | |
48 | ||
240f3905 | 49 | if (vm_write) { |
e7c24607 | 50 | copied = copy_page_from_iter(page, offset, copy, iter); |
240f3905 | 51 | set_page_dirty_lock(page); |
fcf63409 | 52 | } else { |
70eca12d | 53 | copied = copy_page_to_iter(page, offset, copy, iter); |
fcf63409 | 54 | } |
70eca12d AV |
55 | len -= copied; |
56 | if (copied < copy && iov_iter_count(iter)) | |
57 | return -EFAULT; | |
58 | offset = 0; | |
fcf63409 | 59 | } |
70eca12d | 60 | return 0; |
fcf63409 CY |
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 | |
4bafbec7 | 70 | * @iter: where to copy to/from locally |
fcf63409 CY |
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 | |
fcf63409 CY |
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, | |
9f78bdfa | 80 | struct iov_iter *iter, |
fcf63409 CY |
81 | struct page **process_pages, |
82 | struct mm_struct *mm, | |
83 | struct task_struct *task, | |
9acc1a0f | 84 | int vm_write) |
fcf63409 CY |
85 | { |
86 | unsigned long pa = addr & PAGE_MASK; | |
87 | unsigned long start_offset = addr - pa; | |
88 | unsigned long nr_pages; | |
fcf63409 | 89 | ssize_t rc = 0; |
fcf63409 CY |
90 | unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES |
91 | / sizeof(struct pages *); | |
8b7457ef | 92 | unsigned int flags = 0; |
fcf63409 | 93 | |
fcf63409 CY |
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 | ||
d4944b0e LS |
99 | if (vm_write) |
100 | flags |= FOLL_WRITE; | |
101 | ||
4bafbec7 AV |
102 | while (!rc && nr_pages && iov_iter_count(iter)) { |
103 | int pages = min(nr_pages, max_pages_per_loop); | |
8b7457ef | 104 | int locked = 1; |
4bafbec7 | 105 | size_t bytes; |
fcf63409 | 106 | |
1e987790 DH |
107 | /* |
108 | * Get the pages we're interested in. We must | |
8b7457ef | 109 | * access remotely because task/mm might not |
1e987790 DH |
110 | * current/current->mm |
111 | */ | |
8b7457ef LS |
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); | |
4bafbec7 | 117 | if (pages <= 0) |
70eca12d AV |
118 | return -EFAULT; |
119 | ||
4bafbec7 AV |
120 | bytes = pages * PAGE_SIZE - start_offset; |
121 | if (bytes > len) | |
122 | bytes = len; | |
e21345f9 | 123 | |
70eca12d | 124 | rc = process_vm_rw_pages(process_pages, |
4bafbec7 | 125 | start_offset, bytes, iter, |
9acc1a0f | 126 | vm_write); |
4bafbec7 | 127 | len -= bytes; |
fcf63409 | 128 | start_offset = 0; |
4bafbec7 AV |
129 | nr_pages -= pages; |
130 | pa += pages * PAGE_SIZE; | |
131 | while (pages) | |
132 | put_page(process_pages[--pages]); | |
fcf63409 CY |
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 | |
4bafbec7 | 145 | * @iter: where to copy to/from locally |
fcf63409 CY |
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 | |
a5d09bed | 150 | * |
fcf63409 CY |
151 | * Returns the number of bytes read/written or error code. May |
152 | * return less bytes than expected if an error occurs during the copying | |
153 | * process. | |
154 | */ | |
9f78bdfa | 155 | static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, |
fcf63409 CY |
156 | const struct iovec *rvec, |
157 | unsigned long riovcnt, | |
158 | unsigned long flags, int vm_write) | |
159 | { | |
160 | struct task_struct *task; | |
161 | struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; | |
162 | struct page **process_pages = pp_stack; | |
163 | struct mm_struct *mm; | |
164 | unsigned long i; | |
165 | ssize_t rc = 0; | |
fcf63409 CY |
166 | unsigned long nr_pages = 0; |
167 | unsigned long nr_pages_iov; | |
fcf63409 | 168 | ssize_t iov_len; |
9acc1a0f | 169 | size_t total_len = iov_iter_count(iter); |
fcf63409 CY |
170 | |
171 | /* | |
172 | * Work out how many pages of struct pages we're going to need | |
173 | * when eventually calling get_user_pages | |
174 | */ | |
175 | for (i = 0; i < riovcnt; i++) { | |
176 | iov_len = rvec[i].iov_len; | |
177 | if (iov_len > 0) { | |
178 | nr_pages_iov = ((unsigned long)rvec[i].iov_base | |
179 | + iov_len) | |
180 | / PAGE_SIZE - (unsigned long)rvec[i].iov_base | |
181 | / PAGE_SIZE + 1; | |
182 | nr_pages = max(nr_pages, nr_pages_iov); | |
183 | } | |
184 | } | |
185 | ||
186 | if (nr_pages == 0) | |
187 | return 0; | |
188 | ||
189 | if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { | |
190 | /* For reliability don't try to kmalloc more than | |
191 | 2 pages worth */ | |
192 | process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES, | |
193 | sizeof(struct pages *)*nr_pages), | |
194 | GFP_KERNEL); | |
195 | ||
196 | if (!process_pages) | |
197 | return -ENOMEM; | |
198 | } | |
199 | ||
200 | /* Get process information */ | |
2ee08260 | 201 | task = find_get_task_by_vpid(pid); |
fcf63409 CY |
202 | if (!task) { |
203 | rc = -ESRCH; | |
204 | goto free_proc_pages; | |
205 | } | |
206 | ||
caaee623 | 207 | mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS); |
8cdb878d CY |
208 | if (!mm || IS_ERR(mm)) { |
209 | rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; | |
210 | /* | |
211 | * Explicitly map EACCES to EPERM as EPERM is a more a | |
212 | * appropriate error code for process_vw_readv/writev | |
213 | */ | |
214 | if (rc == -EACCES) | |
215 | rc = -EPERM; | |
fcf63409 CY |
216 | goto put_task_struct; |
217 | } | |
218 | ||
9acc1a0f | 219 | for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++) |
fcf63409 CY |
220 | rc = process_vm_rw_single_vec( |
221 | (unsigned long)rvec[i].iov_base, rvec[i].iov_len, | |
9acc1a0f AV |
222 | iter, process_pages, mm, task, vm_write); |
223 | ||
224 | /* copied = space before - space after */ | |
225 | total_len -= iov_iter_count(iter); | |
226 | ||
227 | /* If we have managed to copy any data at all then | |
228 | we return the number of bytes copied. Otherwise | |
229 | we return the error code */ | |
230 | if (total_len) | |
231 | rc = total_len; | |
fcf63409 | 232 | |
fcf63409 CY |
233 | mmput(mm); |
234 | ||
235 | put_task_struct: | |
236 | put_task_struct(task); | |
237 | ||
238 | free_proc_pages: | |
239 | if (process_pages != pp_stack) | |
240 | kfree(process_pages); | |
241 | return rc; | |
242 | } | |
243 | ||
244 | /** | |
245 | * process_vm_rw - check iovecs before calling core routine | |
246 | * @pid: PID of process to read/write from/to | |
247 | * @lvec: iovec array specifying where to copy to/from locally | |
248 | * @liovcnt: size of lvec array | |
249 | * @rvec: iovec array specifying where to copy to/from in the other process | |
250 | * @riovcnt: size of rvec array | |
251 | * @flags: currently unused | |
252 | * @vm_write: 0 if reading from other process, 1 if writing to other process | |
a5d09bed | 253 | * |
fcf63409 CY |
254 | * Returns the number of bytes read/written or error code. May |
255 | * return less bytes than expected if an error occurs during the copying | |
256 | * process. | |
257 | */ | |
258 | static ssize_t process_vm_rw(pid_t pid, | |
259 | const struct iovec __user *lvec, | |
260 | unsigned long liovcnt, | |
261 | const struct iovec __user *rvec, | |
262 | unsigned long riovcnt, | |
263 | unsigned long flags, int vm_write) | |
264 | { | |
265 | struct iovec iovstack_l[UIO_FASTIOV]; | |
266 | struct iovec iovstack_r[UIO_FASTIOV]; | |
267 | struct iovec *iov_l = iovstack_l; | |
268 | struct iovec *iov_r = iovstack_r; | |
9f78bdfa | 269 | struct iov_iter iter; |
fcf63409 | 270 | ssize_t rc; |
17d17e72 | 271 | int dir = vm_write ? WRITE : READ; |
fcf63409 CY |
272 | |
273 | if (flags != 0) | |
274 | return -EINVAL; | |
275 | ||
276 | /* Check iovecs */ | |
17d17e72 AV |
277 | rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); |
278 | if (rc < 0) | |
279 | return rc; | |
280 | if (!iov_iter_count(&iter)) | |
fcf63409 CY |
281 | goto free_iovecs; |
282 | ||
ac34ebb3 CY |
283 | rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV, |
284 | iovstack_r, &iov_r); | |
fcf63409 CY |
285 | if (rc <= 0) |
286 | goto free_iovecs; | |
287 | ||
9f78bdfa | 288 | rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf63409 CY |
289 | |
290 | free_iovecs: | |
291 | if (iov_r != iovstack_r) | |
292 | kfree(iov_r); | |
17d17e72 | 293 | kfree(iov_l); |
fcf63409 CY |
294 | |
295 | return rc; | |
296 | } | |
297 | ||
298 | SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, | |
299 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
300 | unsigned long, riovcnt, unsigned long, flags) | |
301 | { | |
302 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); | |
303 | } | |
304 | ||
305 | SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, | |
306 | const struct iovec __user *, lvec, | |
307 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
308 | unsigned long, riovcnt, unsigned long, flags) | |
309 | { | |
310 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); | |
311 | } | |
312 | ||
313 | #ifdef CONFIG_COMPAT | |
314 | ||
2eb2e141 | 315 | static ssize_t |
fcf63409 CY |
316 | compat_process_vm_rw(compat_pid_t pid, |
317 | const struct compat_iovec __user *lvec, | |
318 | unsigned long liovcnt, | |
319 | const struct compat_iovec __user *rvec, | |
320 | unsigned long riovcnt, | |
321 | unsigned long flags, int vm_write) | |
322 | { | |
323 | struct iovec iovstack_l[UIO_FASTIOV]; | |
324 | struct iovec iovstack_r[UIO_FASTIOV]; | |
325 | struct iovec *iov_l = iovstack_l; | |
326 | struct iovec *iov_r = iovstack_r; | |
9f78bdfa | 327 | struct iov_iter iter; |
fcf63409 | 328 | ssize_t rc = -EFAULT; |
17d17e72 | 329 | int dir = vm_write ? WRITE : READ; |
fcf63409 CY |
330 | |
331 | if (flags != 0) | |
332 | return -EINVAL; | |
333 | ||
17d17e72 AV |
334 | rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); |
335 | if (rc < 0) | |
336 | return rc; | |
337 | if (!iov_iter_count(&iter)) | |
fcf63409 | 338 | goto free_iovecs; |
ac34ebb3 | 339 | rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, |
fcf63409 | 340 | UIO_FASTIOV, iovstack_r, |
ac34ebb3 | 341 | &iov_r); |
fcf63409 CY |
342 | if (rc <= 0) |
343 | goto free_iovecs; | |
344 | ||
9f78bdfa | 345 | rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf63409 CY |
346 | |
347 | free_iovecs: | |
348 | if (iov_r != iovstack_r) | |
349 | kfree(iov_r); | |
17d17e72 | 350 | kfree(iov_l); |
fcf63409 CY |
351 | return rc; |
352 | } | |
353 | ||
2f2728f6 HC |
354 | COMPAT_SYSCALL_DEFINE6(process_vm_readv, 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) | |
fcf63409 CY |
360 | { |
361 | return compat_process_vm_rw(pid, lvec, liovcnt, rvec, | |
362 | riovcnt, flags, 0); | |
363 | } | |
364 | ||
2f2728f6 HC |
365 | COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid, |
366 | const struct compat_iovec __user *, lvec, | |
367 | compat_ulong_t, liovcnt, | |
368 | const struct compat_iovec __user *, rvec, | |
369 | compat_ulong_t, riovcnt, | |
370 | compat_ulong_t, flags) | |
fcf63409 CY |
371 | { |
372 | return compat_process_vm_rw(pid, lvec, liovcnt, rvec, | |
373 | riovcnt, flags, 1); | |
374 | } | |
375 | ||
376 | #endif |