Blame view
mm/process_vm_access.c
9.92 KB
fcf634098
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 |
/* * linux/mm/process_vm_access.c * * Copyright (C) 2010-2011 Christopher Yeoh <cyeoh@au1.ibm.com>, IBM Corp. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/mm.h> #include <linux/uio.h> #include <linux/sched.h> #include <linux/highmem.h> #include <linux/ptrace.h> #include <linux/slab.h> #include <linux/syscalls.h> #ifdef CONFIG_COMPAT #include <linux/compat.h> #endif /** * process_vm_rw_pages - read/write pages from task specified |
4bafbec7b
|
26 |
* @pages: array of pointers to pages we want to copy |
fcf634098
|
27 28 |
* @start_offset: offset in page to start copying from/to * @len: number of bytes to copy |
4bafbec7b
|
29 |
* @iter: where to copy to/from locally |
fcf634098
|
30 |
* @vm_write: 0 means copy from, 1 means copy to |
fcf634098
|
31 32 |
* Returns 0 on success, error code otherwise */ |
70eca12d8
|
33 34 |
static int process_vm_rw_pages(struct page **pages, unsigned offset, |
e21345f9c
|
35 |
size_t len, |
9f78bdfab
|
36 |
struct iov_iter *iter, |
9acc1a0f9
|
37 |
int vm_write) |
fcf634098
|
38 |
{ |
fcf634098
|
39 |
/* Do the copy for each page */ |
9acc1a0f9
|
40 |
while (len && iov_iter_count(iter)) { |
70eca12d8
|
41 |
struct page *page = *pages++; |
e21345f9c
|
42 |
size_t copy = PAGE_SIZE - offset; |
70eca12d8
|
43 |
size_t copied; |
240f3905f
|
44 |
|
e21345f9c
|
45 46 |
if (copy > len) copy = len; |
240f3905f
|
47 |
if (vm_write) { |
e7c24607b
|
48 |
copied = copy_page_from_iter(page, offset, copy, iter); |
240f3905f
|
49 |
set_page_dirty_lock(page); |
fcf634098
|
50 |
} else { |
70eca12d8
|
51 |
copied = copy_page_to_iter(page, offset, copy, iter); |
fcf634098
|
52 |
} |
70eca12d8
|
53 54 55 56 |
len -= copied; if (copied < copy && iov_iter_count(iter)) return -EFAULT; offset = 0; |
fcf634098
|
57 |
} |
70eca12d8
|
58 |
return 0; |
fcf634098
|
59 60 61 62 63 64 65 66 67 |
} /* Maximum number of pages kmalloc'd to hold struct page's during copy */ #define PVM_MAX_KMALLOC_PAGES (PAGE_SIZE * 2) /** * process_vm_rw_single_vec - read/write pages from task specified * @addr: start memory address of target process * @len: size of area to copy to/from |
4bafbec7b
|
68 |
* @iter: where to copy to/from locally |
fcf634098
|
69 70 71 72 73 |
* @process_pages: struct pages area that can store at least * nr_pages_to_copy struct page pointers * @mm: mm for task * @task: task to read/write from * @vm_write: 0 means copy from, 1 means copy to |
fcf634098
|
74 75 76 77 |
* Returns 0 on success or on failure error code */ static int process_vm_rw_single_vec(unsigned long addr, unsigned long len, |
9f78bdfab
|
78 |
struct iov_iter *iter, |
fcf634098
|
79 80 81 |
struct page **process_pages, struct mm_struct *mm, struct task_struct *task, |
9acc1a0f9
|
82 |
int vm_write) |
fcf634098
|
83 84 85 86 |
{ unsigned long pa = addr & PAGE_MASK; unsigned long start_offset = addr - pa; unsigned long nr_pages; |
fcf634098
|
87 |
ssize_t rc = 0; |
fcf634098
|
88 89 |
unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES / sizeof(struct pages *); |
fcf634098
|
90 91 92 93 |
/* Work out address and page range required */ if (len == 0) return 0; nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1; |
4bafbec7b
|
94 95 96 |
while (!rc && nr_pages && iov_iter_count(iter)) { int pages = min(nr_pages, max_pages_per_loop); size_t bytes; |
fcf634098
|
97 |
|
1e9877902
|
98 99 100 101 102 103 104 105 |
/* * Get the pages we're interested in. We must * add FOLL_REMOTE because task/mm might not * current/current->mm */ pages = __get_user_pages_unlocked(task, mm, pa, pages, vm_write, 0, process_pages, FOLL_REMOTE); |
4bafbec7b
|
106 |
if (pages <= 0) |
70eca12d8
|
107 |
return -EFAULT; |
4bafbec7b
|
108 109 110 |
bytes = pages * PAGE_SIZE - start_offset; if (bytes > len) bytes = len; |
e21345f9c
|
111 |
|
70eca12d8
|
112 |
rc = process_vm_rw_pages(process_pages, |
4bafbec7b
|
113 |
start_offset, bytes, iter, |
9acc1a0f9
|
114 |
vm_write); |
4bafbec7b
|
115 |
len -= bytes; |
fcf634098
|
116 |
start_offset = 0; |
4bafbec7b
|
117 118 119 120 |
nr_pages -= pages; pa += pages * PAGE_SIZE; while (pages) put_page(process_pages[--pages]); |
fcf634098
|
121 122 123 124 125 126 127 128 129 130 131 132 |
} return rc; } /* Maximum number of entries for process pages array which lives on stack */ #define PVM_MAX_PP_ARRAY_COUNT 16 /** * process_vm_rw_core - core of reading/writing pages from task specified * @pid: PID of process to read/write from/to |
4bafbec7b
|
133 |
* @iter: where to copy to/from locally |
fcf634098
|
134 135 136 137 138 139 140 141 |
* @rvec: iovec array specifying where to copy to/from in the other process * @riovcnt: size of rvec array * @flags: currently unused * @vm_write: 0 if reading from other process, 1 if writing to other process * Returns the number of bytes read/written or error code. May * return less bytes than expected if an error occurs during the copying * process. */ |
9f78bdfab
|
142 |
static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, |
fcf634098
|
143 144 145 146 147 148 149 150 151 152 |
const struct iovec *rvec, unsigned long riovcnt, unsigned long flags, int vm_write) { struct task_struct *task; struct page *pp_stack[PVM_MAX_PP_ARRAY_COUNT]; struct page **process_pages = pp_stack; struct mm_struct *mm; unsigned long i; ssize_t rc = 0; |
fcf634098
|
153 154 |
unsigned long nr_pages = 0; unsigned long nr_pages_iov; |
fcf634098
|
155 |
ssize_t iov_len; |
9acc1a0f9
|
156 |
size_t total_len = iov_iter_count(iter); |
fcf634098
|
157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 |
/* * Work out how many pages of struct pages we're going to need * when eventually calling get_user_pages */ for (i = 0; i < riovcnt; i++) { iov_len = rvec[i].iov_len; if (iov_len > 0) { nr_pages_iov = ((unsigned long)rvec[i].iov_base + iov_len) / PAGE_SIZE - (unsigned long)rvec[i].iov_base / PAGE_SIZE + 1; nr_pages = max(nr_pages, nr_pages_iov); } } if (nr_pages == 0) return 0; if (nr_pages > PVM_MAX_PP_ARRAY_COUNT) { /* For reliability don't try to kmalloc more than 2 pages worth */ process_pages = kmalloc(min_t(size_t, PVM_MAX_KMALLOC_PAGES, sizeof(struct pages *)*nr_pages), GFP_KERNEL); if (!process_pages) return -ENOMEM; } /* Get process information */ rcu_read_lock(); task = find_task_by_vpid(pid); if (task) get_task_struct(task); rcu_read_unlock(); if (!task) { rc = -ESRCH; goto free_proc_pages; } |
caaee6234
|
197 |
mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS); |
8cdb878dc
|
198 199 200 201 202 203 204 205 |
if (!mm || IS_ERR(mm)) { rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; /* * Explicitly map EACCES to EPERM as EPERM is a more a * appropriate error code for process_vw_readv/writev */ if (rc == -EACCES) rc = -EPERM; |
fcf634098
|
206 207 |
goto put_task_struct; } |
9acc1a0f9
|
208 |
for (i = 0; i < riovcnt && iov_iter_count(iter) && !rc; i++) |
fcf634098
|
209 210 |
rc = process_vm_rw_single_vec( (unsigned long)rvec[i].iov_base, rvec[i].iov_len, |
9acc1a0f9
|
211 212 213 214 215 216 217 218 219 220 |
iter, process_pages, mm, task, vm_write); /* copied = space before - space after */ total_len -= iov_iter_count(iter); /* If we have managed to copy any data at all then we return the number of bytes copied. Otherwise we return the error code */ if (total_len) rc = total_len; |
fcf634098
|
221 |
|
fcf634098
|
222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 |
mmput(mm); put_task_struct: put_task_struct(task); free_proc_pages: if (process_pages != pp_stack) kfree(process_pages); return rc; } /** * process_vm_rw - check iovecs before calling core routine * @pid: PID of process to read/write from/to * @lvec: iovec array specifying where to copy to/from locally * @liovcnt: size of lvec array * @rvec: iovec array specifying where to copy to/from in the other process * @riovcnt: size of rvec array * @flags: currently unused * @vm_write: 0 if reading from other process, 1 if writing to other process * Returns the number of bytes read/written or error code. May * return less bytes than expected if an error occurs during the copying * process. */ static ssize_t process_vm_rw(pid_t pid, const struct iovec __user *lvec, unsigned long liovcnt, const struct iovec __user *rvec, unsigned long riovcnt, unsigned long flags, int vm_write) { struct iovec iovstack_l[UIO_FASTIOV]; struct iovec iovstack_r[UIO_FASTIOV]; struct iovec *iov_l = iovstack_l; struct iovec *iov_r = iovstack_r; |
9f78bdfab
|
257 |
struct iov_iter iter; |
fcf634098
|
258 |
ssize_t rc; |
17d17e728
|
259 |
int dir = vm_write ? WRITE : READ; |
fcf634098
|
260 261 262 263 264 |
if (flags != 0) return -EINVAL; /* Check iovecs */ |
17d17e728
|
265 266 267 268 |
rc = import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); if (rc < 0) return rc; if (!iov_iter_count(&iter)) |
fcf634098
|
269 |
goto free_iovecs; |
ac34ebb3a
|
270 271 |
rc = rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV, iovstack_r, &iov_r); |
fcf634098
|
272 273 |
if (rc <= 0) goto free_iovecs; |
9f78bdfab
|
274 |
rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf634098
|
275 276 277 278 |
free_iovecs: if (iov_r != iovstack_r) kfree(iov_r); |
17d17e728
|
279 |
kfree(iov_l); |
fcf634098
|
280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 |
return rc; } SYSCALL_DEFINE6(process_vm_readv, pid_t, pid, const struct iovec __user *, lvec, unsigned long, liovcnt, const struct iovec __user *, rvec, unsigned long, riovcnt, unsigned long, flags) { return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); } SYSCALL_DEFINE6(process_vm_writev, pid_t, pid, const struct iovec __user *, lvec, unsigned long, liovcnt, const struct iovec __user *, rvec, unsigned long, riovcnt, unsigned long, flags) { return process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); } #ifdef CONFIG_COMPAT |
2eb2e141c
|
300 |
static ssize_t |
fcf634098
|
301 302 303 304 305 306 307 308 309 310 311 |
compat_process_vm_rw(compat_pid_t pid, const struct compat_iovec __user *lvec, unsigned long liovcnt, const struct compat_iovec __user *rvec, unsigned long riovcnt, unsigned long flags, int vm_write) { struct iovec iovstack_l[UIO_FASTIOV]; struct iovec iovstack_r[UIO_FASTIOV]; struct iovec *iov_l = iovstack_l; struct iovec *iov_r = iovstack_r; |
9f78bdfab
|
312 |
struct iov_iter iter; |
fcf634098
|
313 |
ssize_t rc = -EFAULT; |
17d17e728
|
314 |
int dir = vm_write ? WRITE : READ; |
fcf634098
|
315 316 317 |
if (flags != 0) return -EINVAL; |
17d17e728
|
318 319 320 321 |
rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter); if (rc < 0) return rc; if (!iov_iter_count(&iter)) |
fcf634098
|
322 |
goto free_iovecs; |
ac34ebb3a
|
323 |
rc = compat_rw_copy_check_uvector(CHECK_IOVEC_ONLY, rvec, riovcnt, |
fcf634098
|
324 |
UIO_FASTIOV, iovstack_r, |
ac34ebb3a
|
325 |
&iov_r); |
fcf634098
|
326 327 |
if (rc <= 0) goto free_iovecs; |
9f78bdfab
|
328 |
rc = process_vm_rw_core(pid, &iter, iov_r, riovcnt, flags, vm_write); |
fcf634098
|
329 330 331 332 |
free_iovecs: if (iov_r != iovstack_r) kfree(iov_r); |
17d17e728
|
333 |
kfree(iov_l); |
fcf634098
|
334 335 |
return rc; } |
2f2728f6d
|
336 337 338 339 340 341 |
COMPAT_SYSCALL_DEFINE6(process_vm_readv, compat_pid_t, pid, const struct compat_iovec __user *, lvec, compat_ulong_t, liovcnt, const struct compat_iovec __user *, rvec, compat_ulong_t, riovcnt, compat_ulong_t, flags) |
fcf634098
|
342 343 344 345 |
{ return compat_process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 0); } |
2f2728f6d
|
346 347 348 349 350 351 |
COMPAT_SYSCALL_DEFINE6(process_vm_writev, compat_pid_t, pid, const struct compat_iovec __user *, lvec, compat_ulong_t, liovcnt, const struct compat_iovec __user *, rvec, compat_ulong_t, riovcnt, compat_ulong_t, flags) |
fcf634098
|
352 353 354 355 356 357 |
{ return compat_process_vm_rw(pid, lvec, liovcnt, rvec, riovcnt, flags, 1); } #endif |