1 /*
2 * Copyright (c) 2012-2024 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28
29 #include <arm/cpu_data_internal.h>
30 #include <arm/misc_protos.h>
31 #include <kern/thread.h>
32 #include <kern/zalloc_internal.h>
33 #include <sys/errno.h>
34 #include <vm/pmap.h>
35 #include <vm/vm_map_xnu.h>
36 #include <vm/vm_memtag.h>
37 #include <san/kasan.h>
38 #include <arm/pmap.h>
39 #include <arm64/speculation.h>
40
41 #undef copyin
42 #undef copyout
43
44 extern int _bcopyin(const user_addr_t src, char *dst, vm_size_t len);
45 extern int _bcopyinstr(const user_addr_t src, char *dst, vm_size_t max, vm_size_t *actual);
46 extern int _bcopyout(const char *src, user_addr_t dst, vm_size_t len);
47 extern int _copyin_atomic32(const user_addr_t src, uint32_t *dst);
48 extern int _copyin_atomic32_wait_if_equals(const user_addr_t src, uint32_t value);
49 extern int _copyin_atomic64(const user_addr_t src, uint64_t *dst);
50 extern int _copyout_atomic32(uint32_t u32, user_addr_t dst);
51 extern int _copyout_atomic64(uint64_t u64, user_addr_t dst);
52
53
54 extern int copyoutstr_prevalidate(const void *kaddr, user_addr_t uaddr, size_t len);
55
56 extern const vm_map_address_t physmap_base;
57 extern const vm_map_address_t physmap_end;
58
59 /*!
60 * @typedef copyio_flags_t
61 *
62 * @const COPYIO_IN
63 * The copy is user -> kernel.
64 * One of COPYIO_IN or COPYIO_OUT should always be specified.
65 *
66 * @const COPYIO_OUT
67 * The copy is kernel -> user
68 * One of COPYIO_IN or COPYIO_OUT should always be specified.
69 *
70 * @const COPYIO_ALLOW_KERNEL_TO_KERNEL
71 * The "user_address" is allowed to be in the VA space of the kernel.
72 *
73 * @const COPYIO_VALIDATE_USER_ONLY
74 * There isn't really a kernel address used, and only the user address
75 * needs to be validated.
76 *
77 * @const COPYIO_ATOMIC
78 * The copyio operation is atomic, ensure that it is properly aligned.
79 */
80 __options_decl(copyio_flags_t, uint32_t, {
81 COPYIO_IN = 0x0001,
82 COPYIO_OUT = 0x0002,
83 COPYIO_ALLOW_KERNEL_TO_KERNEL = 0x0004,
84 COPYIO_VALIDATE_USER_ONLY = 0x0008,
85 COPYIO_ATOMIC = 0x0010,
86 });
87
88 typedef enum {
89 USER_ACCESS_READ,
90 USER_ACCESS_WRITE
91 } user_access_direction_t;
92
93
94 static inline void
user_access_enable(__unused user_access_direction_t user_access_direction,pmap_t __unused pmap)95 user_access_enable(__unused user_access_direction_t user_access_direction, pmap_t __unused pmap)
96 {
97 #if __ARM_PAN_AVAILABLE__
98 assert(__builtin_arm_rsr("pan") != 0);
99 __builtin_arm_wsr("pan", 0);
100 #endif /* __ARM_PAN_AVAILABLE__ */
101
102 }
103
104 static inline void
user_access_disable(__unused user_access_direction_t user_access_direction,pmap_t __unused pmap)105 user_access_disable(__unused user_access_direction_t user_access_direction, pmap_t __unused pmap)
106 {
107 #if __ARM_PAN_AVAILABLE__
108 __builtin_arm_wsr("pan", 1);
109 #endif /* __ARM_PAN_AVAILABLE__ */
110
111 }
112
113
114 #define WRAP_COPYIO_PAN(_dir, _map, _op) \
115 ({ \
116 int _ret; \
117 user_access_enable(_dir, (_map)->pmap); \
118 _ret = _op; \
119 user_access_disable(_dir, (_map)->pmap); \
120 _ret; \
121 })
122
123 #define WRAP_COPYIO(_dir, _map, _op) WRAP_COPYIO_PAN(_dir, _map, _op)
124
125 /*
126 * Copy sizes bigger than this value will cause a kernel panic.
127 *
128 * Yes, this is an arbitrary fixed limit, but it's almost certainly
129 * a programming error to be copying more than this amount between
130 * user and wired kernel memory in a single invocation on this
131 * platform.
132 */
133 const int copysize_limit_panic = (64 * 1024 * 1024);
134
135 static inline bool
is_kernel_to_kernel_copy(pmap_t pmap)136 is_kernel_to_kernel_copy(pmap_t pmap)
137 {
138 return pmap == kernel_pmap;
139 }
140
141 /**
142 * In order to prevent copies from speculatively targeting the wrong address
143 * space, force kernel-to-kernel copies to target the kernel address space
144 * (TTBR1) and non-kernel copies to target the user address space (TTBR0).
145 *
146 * This should have no non-speculative effect as any address which passes
147 * validation should already have bit 55 (the address space select bit) set
148 * appropriately. If the address would change (i.e. addr is invalid for the copy
149 * type), this function panics and so it must only be called after all other
150 * verification has completed.
151 */
152 static user_addr_t
copy_ensure_address_space_spec(vm_map_t map,const user_addr_t addr)153 copy_ensure_address_space_spec(vm_map_t map, const user_addr_t addr)
154 {
155 user_addr_t new_addr = 0;
156 user_addr_t kaddr = addr | BIT(55);
157 user_addr_t uaddr = addr & (~BIT(55));
158
159 /*
160 * new_addr = is_kernel_to_kernel_copy(...) ? kaddr : uaddr
161 *
162 * The check must be performed explicitly as the compiler lowering of the
163 * actual call may be subject to prediction.
164 */
165 SPECULATION_GUARD_SELECT_XXX(
166 /* out */ new_addr,
167 /* cmp_1 */ map->pmap, /* cmp_2 */ kernel_pmap,
168 /* cc */ "eq", /* sel_1 */ kaddr,
169 /* n_cc */ "ne", /* sel_2 */ uaddr);
170
171 /*
172 * Since we're modifying the address past the validation point, let's be
173 * sure we didn't erroneously change address spaces.
174 *
175 * We have to be careful to hide this check from the optimizer as if it
176 * learns that new_addr == addr, then it is free to (and, indeed, does) use
177 * addr everywhere that new_addr is referenced, which breaks our hardening.
178 */
179 user_addr_t new_addr_opt_hidden = new_addr;
180 __compiler_materialize_and_prevent_reordering_on(new_addr_opt_hidden);
181 if (new_addr_opt_hidden != addr) {
182 panic("copy_ensure_address_space_spec changed address: 0x%llx->0x%llx",
183 addr, new_addr);
184 }
185
186 return new_addr;
187 }
188
189 static int
copy_validate_user_addr(vm_map_t map,const user_addr_t user_addr,vm_size_t nbytes)190 copy_validate_user_addr(vm_map_t map, const user_addr_t user_addr, vm_size_t nbytes)
191 {
192 user_addr_t canonicalized_user_addr = user_addr;
193 user_addr_t user_addr_last;
194 bool is_kernel_to_kernel = is_kernel_to_kernel_copy(map->pmap);
195
196
197 if (__improbable(canonicalized_user_addr < vm_map_min(map) ||
198 os_add_overflow(canonicalized_user_addr, nbytes, &user_addr_last) ||
199 user_addr_last > vm_map_max(map))) {
200 return EFAULT;
201 }
202
203
204 if (!is_kernel_to_kernel) {
205 if (__improbable(canonicalized_user_addr & ARM_TBI_USER_MASK)) {
206 return EINVAL;
207 }
208 }
209
210 return 0;
211 }
212
213 static void
copy_validate_kernel_addr(uintptr_t kernel_addr,vm_size_t nbytes)214 copy_validate_kernel_addr(uintptr_t kernel_addr, vm_size_t nbytes)
215 {
216 uintptr_t kernel_addr_last;
217
218 if (__improbable(os_add_overflow(kernel_addr, nbytes, &kernel_addr_last))) {
219 panic("%s(%p, %lu) - kaddr not in kernel", __func__,
220 (void *)kernel_addr, nbytes);
221 }
222
223 bool in_kva = (VM_KERNEL_STRIP_PTR(kernel_addr) >= VM_MIN_KERNEL_ADDRESS) &&
224 (VM_KERNEL_STRIP_PTR(kernel_addr_last) <= VM_MAX_KERNEL_ADDRESS);
225 bool in_physmap = (VM_KERNEL_STRIP_PTR(kernel_addr) >= physmap_base) &&
226 (VM_KERNEL_STRIP_PTR(kernel_addr_last) <= physmap_end);
227
228 if (__improbable(!(in_kva || in_physmap))) {
229 panic("%s(%p, %lu) - kaddr not in kernel", __func__,
230 (void *)kernel_addr, nbytes);
231 }
232
233 zone_element_bounds_check(kernel_addr, nbytes);
234 }
235
236 /*
237 * Validate the arguments to copy{in,out} on this platform.
238 *
239 * Returns EXDEV when the current thread pmap is the kernel's
240 * which is non fatal for certain routines.
241 */
242 static inline __attribute__((always_inline)) int
copy_validate(vm_map_t map,const user_addr_t user_addr,uintptr_t kernel_addr,vm_size_t nbytes,copyio_flags_t flags)243 copy_validate(vm_map_t map, const user_addr_t user_addr, uintptr_t kernel_addr,
244 vm_size_t nbytes, copyio_flags_t flags)
245 {
246 int ret;
247
248 if (__improbable(nbytes > copysize_limit_panic)) {
249 return EINVAL;
250 }
251
252 ret = copy_validate_user_addr(map, user_addr, nbytes);
253 if (__improbable(ret)) {
254 return ret;
255 }
256
257 if (flags & COPYIO_ATOMIC) {
258 if (__improbable(user_addr & (nbytes - 1))) {
259 return EINVAL;
260 }
261 }
262
263 if ((flags & COPYIO_VALIDATE_USER_ONLY) == 0) {
264 copy_validate_kernel_addr(kernel_addr, nbytes);
265 #if KASAN
266 /* For user copies, asan-check the kernel-side buffer */
267 if (flags & COPYIO_IN) {
268 __asan_storeN(kernel_addr, nbytes);
269 } else {
270 __asan_loadN(kernel_addr, nbytes);
271 }
272 #endif
273 }
274
275 if (is_kernel_to_kernel_copy(map->pmap)) {
276 if (__improbable((flags & COPYIO_ALLOW_KERNEL_TO_KERNEL) == 0)) {
277 return EFAULT;
278 }
279 return EXDEV;
280 }
281
282 return 0;
283 }
284
285 int
copyin_kern(const user_addr_t user_addr,char * kernel_addr,vm_size_t nbytes)286 copyin_kern(const user_addr_t user_addr, char *kernel_addr, vm_size_t nbytes)
287 {
288 bcopy((const char*)(uintptr_t)user_addr, kernel_addr, nbytes);
289
290 return 0;
291 }
292
293 int
copyout_kern(const char * kernel_addr,user_addr_t user_addr,vm_size_t nbytes)294 copyout_kern(const char *kernel_addr, user_addr_t user_addr, vm_size_t nbytes)
295 {
296 bcopy(kernel_addr, (char *)(uintptr_t)user_addr, nbytes);
297
298 return 0;
299 }
300
301 int
copyin(const user_addr_t user_addr,void * kernel_addr,vm_size_t nbytes)302 copyin(const user_addr_t user_addr, void *kernel_addr, vm_size_t nbytes)
303 {
304 vm_map_t map = current_thread()->map;
305 user_addr_t guarded_user_addr;
306 int result;
307
308 if (__improbable(nbytes == 0)) {
309 return 0;
310 }
311
312 result = copy_validate(map, user_addr, (uintptr_t)kernel_addr, nbytes,
313 COPYIO_IN | COPYIO_ALLOW_KERNEL_TO_KERNEL);
314 if (result == EXDEV) {
315 guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
316 return copyin_kern(guarded_user_addr, kernel_addr, nbytes);
317 }
318 if (__improbable(result)) {
319 return result;
320 }
321
322 guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
323
324 return WRAP_COPYIO(USER_ACCESS_READ, map,
325 _bcopyin(guarded_user_addr, kernel_addr, nbytes));
326 }
327
328 /*
329 * copy{in,out}_atomic{32,64}
330 * Read or store an aligned value from userspace as a single memory transaction.
331 * These functions support userspace synchronization features
332 */
333 int
copyin_atomic32(const user_addr_t user_addr,uint32_t * kernel_addr)334 copyin_atomic32(const user_addr_t user_addr, uint32_t *kernel_addr)
335 {
336 vm_map_t map = current_thread()->map;
337 int result = copy_validate(map, user_addr, (uintptr_t)kernel_addr, 4,
338 COPYIO_IN | COPYIO_ATOMIC);
339 if (__improbable(result)) {
340 return result;
341 }
342
343 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
344
345 return WRAP_COPYIO(USER_ACCESS_READ, map,
346 _copyin_atomic32(guarded_user_addr, kernel_addr));
347 }
348
349
350 int
copyin_atomic32_wait_if_equals(const user_addr_t user_addr,uint32_t value)351 copyin_atomic32_wait_if_equals(const user_addr_t user_addr, uint32_t value)
352 {
353 vm_map_t map = current_thread()->map;
354 int result = copy_validate(map, user_addr, 0, 4,
355 COPYIO_OUT | COPYIO_ATOMIC | COPYIO_VALIDATE_USER_ONLY);
356 if (__improbable(result)) {
357 return result;
358 }
359
360 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
361
362 return WRAP_COPYIO(USER_ACCESS_READ, map,
363 _copyin_atomic32_wait_if_equals(guarded_user_addr, value));
364 }
365
366 int
copyin_atomic64(const user_addr_t user_addr,uint64_t * kernel_addr)367 copyin_atomic64(const user_addr_t user_addr, uint64_t *kernel_addr)
368 {
369 vm_map_t map = current_thread()->map;
370 int result = copy_validate(map, user_addr, (uintptr_t)kernel_addr, 8,
371 COPYIO_IN | COPYIO_ATOMIC);
372 if (__improbable(result)) {
373 return result;
374 }
375
376 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
377
378 return WRAP_COPYIO(USER_ACCESS_READ, map,
379 _copyin_atomic64(guarded_user_addr, kernel_addr));
380 }
381
382 int
copyout_atomic32(uint32_t value,user_addr_t user_addr)383 copyout_atomic32(uint32_t value, user_addr_t user_addr)
384 {
385 vm_map_t map = current_thread()->map;
386 int result = copy_validate(map, user_addr, 0, 4,
387 COPYIO_OUT | COPYIO_ATOMIC | COPYIO_VALIDATE_USER_ONLY);
388 if (__improbable(result)) {
389 return result;
390 }
391
392 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
393
394 return WRAP_COPYIO(USER_ACCESS_WRITE, map,
395 _copyout_atomic32(value, guarded_user_addr));
396 }
397
398 int
copyout_atomic64(uint64_t value,user_addr_t user_addr)399 copyout_atomic64(uint64_t value, user_addr_t user_addr)
400 {
401 vm_map_t map = current_thread()->map;
402 int result = copy_validate(map, user_addr, 0, 8,
403 COPYIO_OUT | COPYIO_ATOMIC | COPYIO_VALIDATE_USER_ONLY);
404 if (__improbable(result)) {
405 return result;
406 }
407
408 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
409
410 return WRAP_COPYIO(USER_ACCESS_WRITE, map,
411 _copyout_atomic64(value, guarded_user_addr));
412 }
413
414 int
copyinstr(const user_addr_t user_addr,char * kernel_addr,vm_size_t nbytes,vm_size_t * lencopied)415 copyinstr(const user_addr_t user_addr, char *kernel_addr, vm_size_t nbytes, vm_size_t *lencopied)
416 {
417 vm_map_t map = current_thread()->map;
418 int result;
419 vm_size_t bytes_copied = 0;
420
421 *lencopied = 0;
422 if (__improbable(nbytes == 0)) {
423 return ENAMETOOLONG;
424 }
425
426 result = copy_validate(map, user_addr, (uintptr_t)kernel_addr, nbytes, COPYIO_IN);
427 if (__improbable(result)) {
428 return result;
429 }
430
431 user_addr_t guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
432
433 result = WRAP_COPYIO(USER_ACCESS_READ, map,
434 _bcopyinstr(guarded_user_addr, kernel_addr, nbytes, &bytes_copied));
435
436 if (result != EFAULT) {
437 *lencopied = bytes_copied;
438 }
439 return result;
440 }
441
442 int
copyout(const void * kernel_addr,user_addr_t user_addr,vm_size_t nbytes)443 copyout(const void *kernel_addr, user_addr_t user_addr, vm_size_t nbytes)
444 {
445 vm_map_t map = current_thread()->map;
446 int result;
447 user_addr_t guarded_user_addr;
448
449 if (nbytes == 0) {
450 return 0;
451 }
452
453 result = copy_validate(map, user_addr, (uintptr_t)kernel_addr, nbytes,
454 COPYIO_OUT | COPYIO_ALLOW_KERNEL_TO_KERNEL);
455 if (result == EXDEV) {
456 guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
457 return copyout_kern(kernel_addr, guarded_user_addr, nbytes);
458 }
459 if (__improbable(result)) {
460 return result;
461 }
462
463 guarded_user_addr = copy_ensure_address_space_spec(map, user_addr);
464
465 return WRAP_COPYIO(USER_ACCESS_WRITE, map,
466 _bcopyout(kernel_addr, guarded_user_addr, nbytes));
467 }
468
469 int
copyoutstr_prevalidate(const void * __unused kaddr,user_addr_t __unused uaddr,size_t __unused len)470 copyoutstr_prevalidate(const void *__unused kaddr, user_addr_t __unused uaddr, size_t __unused len)
471 {
472 vm_map_t map = current_thread()->map;
473
474 if (__improbable(is_kernel_to_kernel_copy(map->pmap))) {
475 return EFAULT;
476 }
477
478 return 0;
479 }
480
481 #if (DEBUG || DEVELOPMENT)
482 int
verify_write(const void * source,void * dst,size_t size)483 verify_write(const void *source, void *dst, size_t size)
484 {
485 int rc;
486 disable_preemption();
487 rc = _bcopyout((const char*)source, (user_addr_t)dst, size);
488 enable_preemption();
489 return rc;
490 }
491 #endif
492