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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 | ||
f78f63da | 8 | #include <linux/compat.h> |
fcf63409 CY |
9 | #include <linux/mm.h> |
10 | #include <linux/uio.h> | |
11 | #include <linux/sched.h> | |
6e84f315 | 12 | #include <linux/sched/mm.h> |
fcf63409 CY |
13 | #include <linux/highmem.h> |
14 | #include <linux/ptrace.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/syscalls.h> | |
17 | ||
fcf63409 CY |
18 | /** |
19 | * process_vm_rw_pages - read/write pages from task specified | |
4bafbec7 | 20 | * @pages: array of pointers to pages we want to copy |
f144c390 | 21 | * @offset: offset in page to start copying from/to |
fcf63409 | 22 | * @len: number of bytes to copy |
4bafbec7 | 23 | * @iter: where to copy to/from locally |
fcf63409 | 24 | * @vm_write: 0 means copy from, 1 means copy to |
fcf63409 CY |
25 | * Returns 0 on success, error code otherwise |
26 | */ | |
70eca12d AV |
27 | static int process_vm_rw_pages(struct page **pages, |
28 | unsigned offset, | |
e21345f9 | 29 | size_t len, |
9f78bdfa | 30 | struct iov_iter *iter, |
9acc1a0f | 31 | int vm_write) |
fcf63409 | 32 | { |
fcf63409 | 33 | /* Do the copy for each page */ |
9acc1a0f | 34 | while (len && iov_iter_count(iter)) { |
70eca12d | 35 | struct page *page = *pages++; |
e21345f9 | 36 | size_t copy = PAGE_SIZE - offset; |
70eca12d | 37 | size_t copied; |
240f3905 | 38 | |
e21345f9 AV |
39 | if (copy > len) |
40 | copy = len; | |
41 | ||
803e4572 | 42 | if (vm_write) |
e7c24607 | 43 | copied = copy_page_from_iter(page, offset, copy, iter); |
803e4572 | 44 | else |
70eca12d | 45 | copied = copy_page_to_iter(page, offset, copy, iter); |
803e4572 | 46 | |
70eca12d AV |
47 | len -= copied; |
48 | if (copied < copy && iov_iter_count(iter)) | |
49 | return -EFAULT; | |
50 | offset = 0; | |
fcf63409 | 51 | } |
70eca12d | 52 | return 0; |
fcf63409 CY |
53 | } |
54 | ||
55 | /* Maximum number of pages kmalloc'd to hold struct page's during copy */ | |
56 | #define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2) | |
57 | ||
58 | /** | |
59 | * process_vm_rw_single_vec - read/write pages from task specified | |
60 | * @addr: start memory address of target process | |
61 | * @len: size of area to copy to/from | |
4bafbec7 | 62 | * @iter: where to copy to/from locally |
fcf63409 CY |
63 | * @process_pages: struct pages area that can store at least |
64 | * nr_pages_to_copy struct page pointers | |
65 | * @mm: mm for task | |
66 | * @task: task to read/write from | |
67 | * @vm_write: 0 means copy from, 1 means copy to | |
fcf63409 CY |
68 | * Returns 0 on success or on failure error code |
69 | */ | |
70 | static int process_vm_rw_single_vec(unsigned long addr, | |
71 | unsigned long len, | |
9f78bdfa | 72 | struct iov_iter *iter, |
fcf63409 CY |
73 | struct page **process_pages, |
74 | struct mm_struct *mm, | |
75 | struct task_struct *task, | |
9acc1a0f | 76 | int vm_write) |
fcf63409 CY |
77 | { |
78 | unsigned long pa = addr & PAGE_MASK; | |
79 | unsigned long start_offset = addr - pa; | |
80 | unsigned long nr_pages; | |
fcf63409 | 81 | ssize_t rc = 0; |
fcf63409 CY |
82 | unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES |
83 | / sizeof(struct pages *); | |
8b7457ef | 84 | unsigned int flags = 0; |
fcf63409 | 85 | |
fcf63409 CY |
86 | /* Work out address and page range required */ |
87 | if (len == 0) | |
88 | return 0; | |
89 | nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1; | |
90 | ||
d4944b0e LS |
91 | if (vm_write) |
92 | flags |= FOLL_WRITE; | |
93 | ||
4bafbec7 | 94 | while (!rc && nr_pages && iov_iter_count(iter)) { |
803e4572 | 95 | int pinned_pages = min(nr_pages, max_pages_per_loop); |
8b7457ef | 96 | int locked = 1; |
4bafbec7 | 97 | size_t bytes; |
fcf63409 | 98 | |
1e987790 DH |
99 | /* |
100 | * Get the pages we're interested in. We must | |
8b7457ef | 101 | * access remotely because task/mm might not |
1e987790 DH |
102 | * current/current->mm |
103 | */ | |
d8ed45c5 | 104 | mmap_read_lock(mm); |
64019a2e | 105 | pinned_pages = pin_user_pages_remote(mm, pa, pinned_pages, |
803e4572 JH |
106 | flags, process_pages, |
107 | NULL, &locked); | |
8b7457ef | 108 | if (locked) |
d8ed45c5 | 109 | mmap_read_unlock(mm); |
803e4572 | 110 | if (pinned_pages <= 0) |
70eca12d AV |
111 | return -EFAULT; |
112 | ||
803e4572 | 113 | bytes = pinned_pages * PAGE_SIZE - start_offset; |
4bafbec7 AV |
114 | if (bytes > len) |
115 | bytes = len; | |
e21345f9 | 116 | |
70eca12d | 117 | rc = process_vm_rw_pages(process_pages, |
4bafbec7 | 118 | start_offset, bytes, iter, |
9acc1a0f | 119 | vm_write); |
4bafbec7 | 120 | len -= bytes; |
fcf63409 | 121 | start_offset = 0; |
803e4572 JH |
122 | nr_pages -= pinned_pages; |
123 | pa += pinned_pages * PAGE_SIZE; | |
124 | ||
125 | /* If vm_write is set, the pages need to be made dirty: */ | |
f1f6a7dd JH |
126 | unpin_user_pages_dirty_lock(process_pages, pinned_pages, |
127 | vm_write); | |
fcf63409 CY |
128 | } |
129 | ||
130 | return rc; | |
131 | } | |
132 | ||
133 | /* Maximum number of entries for process pages array | |
134 | which lives on stack */ | |
135 | #define PVM_MAX_PP_ARRAY_COUNT 16 | |
136 | ||
137 | /** | |
138 | * process_vm_rw_core - core of reading/writing pages from task specified | |
139 | * @pid: PID of process to read/write from/to | |
4bafbec7 | 140 | * @iter: where to copy to/from locally |
fcf63409 CY |
141 | * @rvec: iovec array specifying where to copy to/from in the other process |
142 | * @riovcnt: size of rvec array | |
143 | * @flags: currently unused | |
144 | * @vm_write: 0 if reading from other process, 1 if writing to other process | |
a5d09bed | 145 | * |
fcf63409 CY |
146 | * Returns the number of bytes read/written or error code. May |
147 | * return less bytes than expected if an error occurs during the copying | |
148 | * process. | |
149 | */ | |
9f78bdfa | 150 | static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, |
fcf63409 CY |
151 | const struct iovec *rvec, |
152 | unsigned long riovcnt, | |
153 | unsigned long flags, int vm_write) | |
154 | { | |
155 | struct task_struct *task; | |
156 | struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; | |
157 | struct page **process_pages = pp_stack; | |
158 | struct mm_struct *mm; | |
159 | unsigned long i; | |
160 | ssize_t rc = 0; | |
fcf63409 CY |
161 | unsigned long nr_pages = 0; |
162 | unsigned long nr_pages_iov; | |
fcf63409 | 163 | ssize_t iov_len; |
9acc1a0f | 164 | size_t total_len = iov_iter_count(iter); |
fcf63409 CY |
165 | |
166 | /* | |
167 | * Work out how many pages of struct pages we're going to need | |
168 | * when eventually calling get_user_pages | |
169 | */ | |
170 | for (i = 0; i < riovcnt; i++) { | |
171 | iov_len = rvec[i].iov_len; | |
172 | if (iov_len > 0) { | |
173 | nr_pages_iov = ((unsigned long)rvec[i].iov_base | |
174 | + iov_len) | |
175 | / PAGE_SIZE - (unsigned long)rvec[i].iov_base | |
176 | / PAGE_SIZE + 1; | |
177 | nr_pages = max(nr_pages, nr_pages_iov); | |
178 | } | |
179 | } | |
180 | ||
181 | if (nr_pages == 0) | |
182 | return 0; | |
183 | ||
184 | if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { | |
185 | /* For reliability don't try to kmalloc more than | |
186 | 2 pages worth */ | |
187 | process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES, | |
188 | sizeof(struct pages *)*nr_pages), | |
189 | GFP_KERNEL); | |
190 | ||
191 | if (!process_pages) | |
192 | return -ENOMEM; | |
193 | } | |
194 | ||
195 | /* Get process information */ | |
2ee08260 | 196 | task = find_get_task_by_vpid(pid); |
fcf63409 CY |
197 | if (!task) { |
198 | rc = -ESRCH; | |
199 | goto free_proc_pages; | |
200 | } | |
201 | ||
caaee623 | 202 | mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS); |
8cdb878d CY |
203 | if (!mm || IS_ERR(mm)) { |
204 | rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; | |
205 | /* | |
8d09db80 | 206 | * Explicitly map EACCES to EPERM as EPERM is a more |
8cdb878d CY |
207 | * appropriate error code for process_vw_readv/writev |
208 | */ | |
209 | if (rc == -EACCES) | |
210 | rc = -EPERM; | |
fcf63409 CY |
211 | goto put_task_struct; |
212 | } | |
213 | ||
9acc1a0f | 214 | for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++) |
fcf63409 CY |
215 | rc = process_vm_rw_single_vec( |
216 | (unsigned long)rvec[i].iov_base, rvec[i].iov_len, | |
9acc1a0f AV |
217 | iter, process_pages, mm, task, vm_write); |
218 | ||
219 | /* copied = space before - space after */ | |
220 | total_len -= iov_iter_count(iter); | |
221 | ||
222 | /* If we have managed to copy any data at all then | |
223 | we return the number of bytes copied. Otherwise | |
224 | we return the error code */ | |
225 | if (total_len) | |
226 | rc = total_len; | |
fcf63409 | 227 | |
fcf63409 CY |
228 | mmput(mm); |
229 | ||
230 | put_task_struct: | |
231 | put_task_struct(task); | |
232 | ||
233 | free_proc_pages: | |
234 | if (process_pages != pp_stack) | |
235 | kfree(process_pages); | |
236 | return rc; | |
237 | } | |
238 | ||
239 | /** | |
240 | * process_vm_rw - check iovecs before calling core routine | |
241 | * @pid: PID of process to read/write from/to | |
242 | * @lvec: iovec array specifying where to copy to/from locally | |
243 | * @liovcnt: size of lvec array | |
244 | * @rvec: iovec array specifying where to copy to/from in the other process | |
245 | * @riovcnt: size of rvec array | |
246 | * @flags: currently unused | |
247 | * @vm_write: 0 if reading from other process, 1 if writing to other process | |
a5d09bed | 248 | * |
fcf63409 CY |
249 | * Returns the number of bytes read/written or error code. May |
250 | * return less bytes than expected if an error occurs during the copying | |
251 | * process. | |
252 | */ | |
253 | static ssize_t process_vm_rw(pid_t pid, | |
254 | const struct iovec __user *lvec, | |
255 | unsigned long liovcnt, | |
256 | const struct iovec __user *rvec, | |
257 | unsigned long riovcnt, | |
258 | unsigned long flags, int vm_write) | |
259 | { | |
260 | struct iovec iovstack_l[UIO_FASTIOV]; | |
261 | struct iovec iovstack_r[UIO_FASTIOV]; | |
262 | struct iovec *iov_l = iovstack_l; | |
95c9ae14 | 263 | struct iovec *iov_r; |
9f78bdfa | 264 | struct iov_iter iter; |
fcf63409 | 265 | ssize_t rc; |
17d17e72 | 266 | int dir = vm_write ? WRITE : READ; |
fcf63409 CY |
267 | |
268 | if (flags != 0) | |
269 | return -EINVAL; | |
270 | ||
271 | /* Check iovecs */ | |
17d17e72 AV |
272 | rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); |
273 | if (rc < 0) | |
274 | return rc; | |
275 | if (!iov_iter_count(&iter)) | |
bfdc5970 | 276 | goto free_iov_l; |
38dc5079 JA |
277 | iov_r = iovec_from_user(rvec, riovcnt, UIO_FASTIOV, iovstack_r, |
278 | in_compat_syscall()); | |
bfdc5970 CH |
279 | if (IS_ERR(iov_r)) { |
280 | rc = PTR_ERR(iov_r); | |
281 | goto free_iov_l; | |
282 | } | |
9f78bdfa | 283 | rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf63409 CY |
284 | if (iov_r != iovstack_r) |
285 | kfree(iov_r); | |
bfdc5970 | 286 | free_iov_l: |
17d17e72 | 287 | kfree(iov_l); |
fcf63409 CY |
288 | return rc; |
289 | } | |
290 | ||
291 | SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, | |
292 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
293 | unsigned long, riovcnt, unsigned long, flags) | |
294 | { | |
295 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); | |
296 | } | |
297 | ||
298 | SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, | |
299 | const struct iovec __user *, lvec, | |
300 | unsigned long, liovcnt, const struct iovec __user *, rvec, | |
301 | unsigned long, riovcnt, unsigned long, flags) | |
302 | { | |
303 | return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); | |
304 | } |