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bffa986c AK |
1 | /* |
2 | * This file contains common generic and tag-based KASAN code. | |
3 | * | |
4 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
5 | * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> | |
6 | * | |
7 | * Some code borrowed from https://github.com/xairy/kasan-prototype by | |
8 | * Andrey Konovalov <andreyknvl@gmail.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | */ | |
15 | ||
16 | #include <linux/export.h> | |
17 | #include <linux/interrupt.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/kasan.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/kmemleak.h> | |
22 | #include <linux/linkage.h> | |
23 | #include <linux/memblock.h> | |
24 | #include <linux/memory.h> | |
25 | #include <linux/mm.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/printk.h> | |
28 | #include <linux/sched.h> | |
29 | #include <linux/sched/task_stack.h> | |
30 | #include <linux/slab.h> | |
31 | #include <linux/stacktrace.h> | |
32 | #include <linux/string.h> | |
33 | #include <linux/types.h> | |
34 | #include <linux/vmalloc.h> | |
35 | #include <linux/bug.h> | |
36 | ||
37 | #include "kasan.h" | |
38 | #include "../slab.h" | |
39 | ||
40 | static inline int in_irqentry_text(unsigned long ptr) | |
41 | { | |
42 | return (ptr >= (unsigned long)&__irqentry_text_start && | |
43 | ptr < (unsigned long)&__irqentry_text_end) || | |
44 | (ptr >= (unsigned long)&__softirqentry_text_start && | |
45 | ptr < (unsigned long)&__softirqentry_text_end); | |
46 | } | |
47 | ||
48 | static inline void filter_irq_stacks(struct stack_trace *trace) | |
49 | { | |
50 | int i; | |
51 | ||
52 | if (!trace->nr_entries) | |
53 | return; | |
54 | for (i = 0; i < trace->nr_entries; i++) | |
55 | if (in_irqentry_text(trace->entries[i])) { | |
56 | /* Include the irqentry function into the stack. */ | |
57 | trace->nr_entries = i + 1; | |
58 | break; | |
59 | } | |
60 | } | |
61 | ||
62 | static inline depot_stack_handle_t save_stack(gfp_t flags) | |
63 | { | |
64 | unsigned long entries[KASAN_STACK_DEPTH]; | |
65 | struct stack_trace trace = { | |
66 | .nr_entries = 0, | |
67 | .entries = entries, | |
68 | .max_entries = KASAN_STACK_DEPTH, | |
69 | .skip = 0 | |
70 | }; | |
71 | ||
72 | save_stack_trace(&trace); | |
73 | filter_irq_stacks(&trace); | |
74 | if (trace.nr_entries != 0 && | |
75 | trace.entries[trace.nr_entries-1] == ULONG_MAX) | |
76 | trace.nr_entries--; | |
77 | ||
78 | return depot_save_stack(&trace, flags); | |
79 | } | |
80 | ||
81 | static inline void set_track(struct kasan_track *track, gfp_t flags) | |
82 | { | |
83 | track->pid = current->pid; | |
84 | track->stack = save_stack(flags); | |
85 | } | |
86 | ||
87 | void kasan_enable_current(void) | |
88 | { | |
89 | current->kasan_depth++; | |
90 | } | |
91 | ||
92 | void kasan_disable_current(void) | |
93 | { | |
94 | current->kasan_depth--; | |
95 | } | |
96 | ||
97 | void kasan_check_read(const volatile void *p, unsigned int size) | |
98 | { | |
99 | check_memory_region((unsigned long)p, size, false, _RET_IP_); | |
100 | } | |
101 | EXPORT_SYMBOL(kasan_check_read); | |
102 | ||
103 | void kasan_check_write(const volatile void *p, unsigned int size) | |
104 | { | |
105 | check_memory_region((unsigned long)p, size, true, _RET_IP_); | |
106 | } | |
107 | EXPORT_SYMBOL(kasan_check_write); | |
108 | ||
109 | #undef memset | |
110 | void *memset(void *addr, int c, size_t len) | |
111 | { | |
112 | check_memory_region((unsigned long)addr, len, true, _RET_IP_); | |
113 | ||
114 | return __memset(addr, c, len); | |
115 | } | |
116 | ||
117 | #undef memmove | |
118 | void *memmove(void *dest, const void *src, size_t len) | |
119 | { | |
120 | check_memory_region((unsigned long)src, len, false, _RET_IP_); | |
121 | check_memory_region((unsigned long)dest, len, true, _RET_IP_); | |
122 | ||
123 | return __memmove(dest, src, len); | |
124 | } | |
125 | ||
126 | #undef memcpy | |
127 | void *memcpy(void *dest, const void *src, size_t len) | |
128 | { | |
129 | check_memory_region((unsigned long)src, len, false, _RET_IP_); | |
130 | check_memory_region((unsigned long)dest, len, true, _RET_IP_); | |
131 | ||
132 | return __memcpy(dest, src, len); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Poisons the shadow memory for 'size' bytes starting from 'addr'. | |
137 | * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE. | |
138 | */ | |
139 | void kasan_poison_shadow(const void *address, size_t size, u8 value) | |
140 | { | |
141 | void *shadow_start, *shadow_end; | |
142 | ||
7f94ffbc AK |
143 | /* |
144 | * Perform shadow offset calculation based on untagged address, as | |
145 | * some of the callers (e.g. kasan_poison_object_data) pass tagged | |
146 | * addresses to this function. | |
147 | */ | |
148 | address = reset_tag(address); | |
149 | ||
bffa986c AK |
150 | shadow_start = kasan_mem_to_shadow(address); |
151 | shadow_end = kasan_mem_to_shadow(address + size); | |
152 | ||
153 | __memset(shadow_start, value, shadow_end - shadow_start); | |
154 | } | |
155 | ||
156 | void kasan_unpoison_shadow(const void *address, size_t size) | |
157 | { | |
7f94ffbc AK |
158 | u8 tag = get_tag(address); |
159 | ||
160 | /* | |
161 | * Perform shadow offset calculation based on untagged address, as | |
162 | * some of the callers (e.g. kasan_unpoison_object_data) pass tagged | |
163 | * addresses to this function. | |
164 | */ | |
165 | address = reset_tag(address); | |
166 | ||
167 | kasan_poison_shadow(address, size, tag); | |
bffa986c AK |
168 | |
169 | if (size & KASAN_SHADOW_MASK) { | |
170 | u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); | |
7f94ffbc AK |
171 | |
172 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) | |
173 | *shadow = tag; | |
174 | else | |
175 | *shadow = size & KASAN_SHADOW_MASK; | |
bffa986c AK |
176 | } |
177 | } | |
178 | ||
179 | static void __kasan_unpoison_stack(struct task_struct *task, const void *sp) | |
180 | { | |
181 | void *base = task_stack_page(task); | |
182 | size_t size = sp - base; | |
183 | ||
184 | kasan_unpoison_shadow(base, size); | |
185 | } | |
186 | ||
187 | /* Unpoison the entire stack for a task. */ | |
188 | void kasan_unpoison_task_stack(struct task_struct *task) | |
189 | { | |
190 | __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE); | |
191 | } | |
192 | ||
193 | /* Unpoison the stack for the current task beyond a watermark sp value. */ | |
194 | asmlinkage void kasan_unpoison_task_stack_below(const void *watermark) | |
195 | { | |
196 | /* | |
197 | * Calculate the task stack base address. Avoid using 'current' | |
198 | * because this function is called by early resume code which hasn't | |
199 | * yet set up the percpu register (%gs). | |
200 | */ | |
201 | void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1)); | |
202 | ||
203 | kasan_unpoison_shadow(base, watermark - base); | |
204 | } | |
205 | ||
206 | /* | |
207 | * Clear all poison for the region between the current SP and a provided | |
208 | * watermark value, as is sometimes required prior to hand-crafted asm function | |
209 | * returns in the middle of functions. | |
210 | */ | |
211 | void kasan_unpoison_stack_above_sp_to(const void *watermark) | |
212 | { | |
213 | const void *sp = __builtin_frame_address(0); | |
214 | size_t size = watermark - sp; | |
215 | ||
216 | if (WARN_ON(sp > watermark)) | |
217 | return; | |
218 | kasan_unpoison_shadow(sp, size); | |
219 | } | |
220 | ||
221 | void kasan_alloc_pages(struct page *page, unsigned int order) | |
222 | { | |
7f94ffbc AK |
223 | if (unlikely(PageHighMem(page))) |
224 | return; | |
225 | kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); | |
bffa986c AK |
226 | } |
227 | ||
228 | void kasan_free_pages(struct page *page, unsigned int order) | |
229 | { | |
230 | if (likely(!PageHighMem(page))) | |
231 | kasan_poison_shadow(page_address(page), | |
232 | PAGE_SIZE << order, | |
233 | KASAN_FREE_PAGE); | |
234 | } | |
235 | ||
236 | /* | |
237 | * Adaptive redzone policy taken from the userspace AddressSanitizer runtime. | |
238 | * For larger allocations larger redzones are used. | |
239 | */ | |
240 | static inline unsigned int optimal_redzone(unsigned int object_size) | |
241 | { | |
7f94ffbc AK |
242 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
243 | return 0; | |
244 | ||
bffa986c AK |
245 | return |
246 | object_size <= 64 - 16 ? 16 : | |
247 | object_size <= 128 - 32 ? 32 : | |
248 | object_size <= 512 - 64 ? 64 : | |
249 | object_size <= 4096 - 128 ? 128 : | |
250 | object_size <= (1 << 14) - 256 ? 256 : | |
251 | object_size <= (1 << 15) - 512 ? 512 : | |
252 | object_size <= (1 << 16) - 1024 ? 1024 : 2048; | |
253 | } | |
254 | ||
255 | void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, | |
256 | slab_flags_t *flags) | |
257 | { | |
258 | unsigned int orig_size = *size; | |
7f94ffbc | 259 | unsigned int redzone_size; |
bffa986c AK |
260 | int redzone_adjust; |
261 | ||
262 | /* Add alloc meta. */ | |
263 | cache->kasan_info.alloc_meta_offset = *size; | |
264 | *size += sizeof(struct kasan_alloc_meta); | |
265 | ||
266 | /* Add free meta. */ | |
7f94ffbc AK |
267 | if (IS_ENABLED(CONFIG_KASAN_GENERIC) && |
268 | (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor || | |
269 | cache->object_size < sizeof(struct kasan_free_meta))) { | |
bffa986c AK |
270 | cache->kasan_info.free_meta_offset = *size; |
271 | *size += sizeof(struct kasan_free_meta); | |
272 | } | |
bffa986c | 273 | |
7f94ffbc AK |
274 | redzone_size = optimal_redzone(cache->object_size); |
275 | redzone_adjust = redzone_size - (*size - cache->object_size); | |
bffa986c AK |
276 | if (redzone_adjust > 0) |
277 | *size += redzone_adjust; | |
278 | ||
279 | *size = min_t(unsigned int, KMALLOC_MAX_SIZE, | |
7f94ffbc | 280 | max(*size, cache->object_size + redzone_size)); |
bffa986c AK |
281 | |
282 | /* | |
283 | * If the metadata doesn't fit, don't enable KASAN at all. | |
284 | */ | |
285 | if (*size <= cache->kasan_info.alloc_meta_offset || | |
286 | *size <= cache->kasan_info.free_meta_offset) { | |
287 | cache->kasan_info.alloc_meta_offset = 0; | |
288 | cache->kasan_info.free_meta_offset = 0; | |
289 | *size = orig_size; | |
290 | return; | |
291 | } | |
292 | ||
7f94ffbc AK |
293 | cache->align = round_up(cache->align, KASAN_SHADOW_SCALE_SIZE); |
294 | ||
bffa986c AK |
295 | *flags |= SLAB_KASAN; |
296 | } | |
297 | ||
298 | size_t kasan_metadata_size(struct kmem_cache *cache) | |
299 | { | |
300 | return (cache->kasan_info.alloc_meta_offset ? | |
301 | sizeof(struct kasan_alloc_meta) : 0) + | |
302 | (cache->kasan_info.free_meta_offset ? | |
303 | sizeof(struct kasan_free_meta) : 0); | |
304 | } | |
305 | ||
306 | struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, | |
307 | const void *object) | |
308 | { | |
309 | BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32); | |
310 | return (void *)object + cache->kasan_info.alloc_meta_offset; | |
311 | } | |
312 | ||
313 | struct kasan_free_meta *get_free_info(struct kmem_cache *cache, | |
314 | const void *object) | |
315 | { | |
316 | BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32); | |
317 | return (void *)object + cache->kasan_info.free_meta_offset; | |
318 | } | |
319 | ||
320 | void kasan_poison_slab(struct page *page) | |
321 | { | |
322 | kasan_poison_shadow(page_address(page), | |
323 | PAGE_SIZE << compound_order(page), | |
324 | KASAN_KMALLOC_REDZONE); | |
325 | } | |
326 | ||
327 | void kasan_unpoison_object_data(struct kmem_cache *cache, void *object) | |
328 | { | |
329 | kasan_unpoison_shadow(object, cache->object_size); | |
330 | } | |
331 | ||
332 | void kasan_poison_object_data(struct kmem_cache *cache, void *object) | |
333 | { | |
334 | kasan_poison_shadow(object, | |
335 | round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE), | |
336 | KASAN_KMALLOC_REDZONE); | |
337 | } | |
338 | ||
7f94ffbc AK |
339 | /* |
340 | * Since it's desirable to only call object contructors once during slab | |
341 | * allocation, we preassign tags to all such objects. Also preassign tags for | |
342 | * SLAB_TYPESAFE_BY_RCU slabs to avoid use-after-free reports. | |
343 | * For SLAB allocator we can't preassign tags randomly since the freelist is | |
344 | * stored as an array of indexes instead of a linked list. Assign tags based | |
345 | * on objects indexes, so that objects that are next to each other get | |
346 | * different tags. | |
347 | * After a tag is assigned, the object always gets allocated with the same tag. | |
348 | * The reason is that we can't change tags for objects with constructors on | |
349 | * reallocation (even for non-SLAB_TYPESAFE_BY_RCU), because the constructor | |
350 | * code can save the pointer to the object somewhere (e.g. in the object | |
351 | * itself). Then if we retag it, the old saved pointer will become invalid. | |
352 | */ | |
353 | static u8 assign_tag(struct kmem_cache *cache, const void *object, bool new) | |
354 | { | |
355 | if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU)) | |
356 | return new ? KASAN_TAG_KERNEL : random_tag(); | |
357 | ||
358 | #ifdef CONFIG_SLAB | |
359 | return (u8)obj_to_index(cache, virt_to_page(object), (void *)object); | |
360 | #else | |
361 | return new ? random_tag() : get_tag(object); | |
362 | #endif | |
363 | } | |
364 | ||
bffa986c AK |
365 | void *kasan_init_slab_obj(struct kmem_cache *cache, const void *object) |
366 | { | |
367 | struct kasan_alloc_meta *alloc_info; | |
368 | ||
369 | if (!(cache->flags & SLAB_KASAN)) | |
370 | return (void *)object; | |
371 | ||
372 | alloc_info = get_alloc_info(cache, object); | |
373 | __memset(alloc_info, 0, sizeof(*alloc_info)); | |
374 | ||
7f94ffbc AK |
375 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
376 | object = set_tag(object, assign_tag(cache, object, true)); | |
377 | ||
bffa986c AK |
378 | return (void *)object; |
379 | } | |
380 | ||
381 | void *kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags) | |
382 | { | |
383 | return kasan_kmalloc(cache, object, cache->object_size, flags); | |
384 | } | |
385 | ||
7f94ffbc AK |
386 | static inline bool shadow_invalid(u8 tag, s8 shadow_byte) |
387 | { | |
388 | if (IS_ENABLED(CONFIG_KASAN_GENERIC)) | |
389 | return shadow_byte < 0 || | |
390 | shadow_byte >= KASAN_SHADOW_SCALE_SIZE; | |
391 | else | |
392 | return tag != (u8)shadow_byte; | |
393 | } | |
394 | ||
bffa986c AK |
395 | static bool __kasan_slab_free(struct kmem_cache *cache, void *object, |
396 | unsigned long ip, bool quarantine) | |
397 | { | |
398 | s8 shadow_byte; | |
7f94ffbc AK |
399 | u8 tag; |
400 | void *tagged_object; | |
bffa986c AK |
401 | unsigned long rounded_up_size; |
402 | ||
7f94ffbc AK |
403 | tag = get_tag(object); |
404 | tagged_object = object; | |
405 | object = reset_tag(object); | |
406 | ||
bffa986c AK |
407 | if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) != |
408 | object)) { | |
7f94ffbc | 409 | kasan_report_invalid_free(tagged_object, ip); |
bffa986c AK |
410 | return true; |
411 | } | |
412 | ||
413 | /* RCU slabs could be legally used after free within the RCU period */ | |
414 | if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) | |
415 | return false; | |
416 | ||
417 | shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); | |
7f94ffbc AK |
418 | if (shadow_invalid(tag, shadow_byte)) { |
419 | kasan_report_invalid_free(tagged_object, ip); | |
bffa986c AK |
420 | return true; |
421 | } | |
422 | ||
423 | rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE); | |
424 | kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); | |
425 | ||
7f94ffbc AK |
426 | if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) || |
427 | unlikely(!(cache->flags & SLAB_KASAN))) | |
bffa986c AK |
428 | return false; |
429 | ||
430 | set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT); | |
431 | quarantine_put(get_free_info(cache, object), cache); | |
7f94ffbc AK |
432 | |
433 | return IS_ENABLED(CONFIG_KASAN_GENERIC); | |
bffa986c AK |
434 | } |
435 | ||
436 | bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip) | |
437 | { | |
438 | return __kasan_slab_free(cache, object, ip, true); | |
439 | } | |
440 | ||
441 | void *kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size, | |
442 | gfp_t flags) | |
443 | { | |
444 | unsigned long redzone_start; | |
445 | unsigned long redzone_end; | |
7f94ffbc | 446 | u8 tag; |
bffa986c AK |
447 | |
448 | if (gfpflags_allow_blocking(flags)) | |
449 | quarantine_reduce(); | |
450 | ||
451 | if (unlikely(object == NULL)) | |
452 | return NULL; | |
453 | ||
454 | redzone_start = round_up((unsigned long)(object + size), | |
455 | KASAN_SHADOW_SCALE_SIZE); | |
456 | redzone_end = round_up((unsigned long)object + cache->object_size, | |
457 | KASAN_SHADOW_SCALE_SIZE); | |
458 | ||
7f94ffbc AK |
459 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
460 | tag = assign_tag(cache, object, false); | |
461 | ||
462 | /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */ | |
463 | kasan_unpoison_shadow(set_tag(object, tag), size); | |
bffa986c AK |
464 | kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, |
465 | KASAN_KMALLOC_REDZONE); | |
466 | ||
467 | if (cache->flags & SLAB_KASAN) | |
468 | set_track(&get_alloc_info(cache, object)->alloc_track, flags); | |
469 | ||
7f94ffbc | 470 | return set_tag(object, tag); |
bffa986c AK |
471 | } |
472 | EXPORT_SYMBOL(kasan_kmalloc); | |
473 | ||
474 | void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags) | |
475 | { | |
476 | struct page *page; | |
477 | unsigned long redzone_start; | |
478 | unsigned long redzone_end; | |
479 | ||
480 | if (gfpflags_allow_blocking(flags)) | |
481 | quarantine_reduce(); | |
482 | ||
483 | if (unlikely(ptr == NULL)) | |
484 | return NULL; | |
485 | ||
486 | page = virt_to_page(ptr); | |
487 | redzone_start = round_up((unsigned long)(ptr + size), | |
488 | KASAN_SHADOW_SCALE_SIZE); | |
489 | redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page)); | |
490 | ||
491 | kasan_unpoison_shadow(ptr, size); | |
492 | kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, | |
493 | KASAN_PAGE_REDZONE); | |
494 | ||
495 | return (void *)ptr; | |
496 | } | |
497 | ||
498 | void *kasan_krealloc(const void *object, size_t size, gfp_t flags) | |
499 | { | |
500 | struct page *page; | |
501 | ||
502 | if (unlikely(object == ZERO_SIZE_PTR)) | |
503 | return (void *)object; | |
504 | ||
505 | page = virt_to_head_page(object); | |
506 | ||
507 | if (unlikely(!PageSlab(page))) | |
508 | return kasan_kmalloc_large(object, size, flags); | |
509 | else | |
510 | return kasan_kmalloc(page->slab_cache, object, size, flags); | |
511 | } | |
512 | ||
513 | void kasan_poison_kfree(void *ptr, unsigned long ip) | |
514 | { | |
515 | struct page *page; | |
516 | ||
517 | page = virt_to_head_page(ptr); | |
518 | ||
519 | if (unlikely(!PageSlab(page))) { | |
7f94ffbc | 520 | if (reset_tag(ptr) != page_address(page)) { |
bffa986c AK |
521 | kasan_report_invalid_free(ptr, ip); |
522 | return; | |
523 | } | |
524 | kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), | |
525 | KASAN_FREE_PAGE); | |
526 | } else { | |
527 | __kasan_slab_free(page->slab_cache, ptr, ip, false); | |
528 | } | |
529 | } | |
530 | ||
531 | void kasan_kfree_large(void *ptr, unsigned long ip) | |
532 | { | |
7f94ffbc | 533 | if (reset_tag(ptr) != page_address(virt_to_head_page(ptr))) |
bffa986c AK |
534 | kasan_report_invalid_free(ptr, ip); |
535 | /* The object will be poisoned by page_alloc. */ | |
536 | } | |
537 | ||
538 | int kasan_module_alloc(void *addr, size_t size) | |
539 | { | |
540 | void *ret; | |
541 | size_t scaled_size; | |
542 | size_t shadow_size; | |
543 | unsigned long shadow_start; | |
544 | ||
545 | shadow_start = (unsigned long)kasan_mem_to_shadow(addr); | |
546 | scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT; | |
547 | shadow_size = round_up(scaled_size, PAGE_SIZE); | |
548 | ||
549 | if (WARN_ON(!PAGE_ALIGNED(shadow_start))) | |
550 | return -EINVAL; | |
551 | ||
552 | ret = __vmalloc_node_range(shadow_size, 1, shadow_start, | |
553 | shadow_start + shadow_size, | |
080eb83f | 554 | GFP_KERNEL, |
bffa986c AK |
555 | PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE, |
556 | __builtin_return_address(0)); | |
557 | ||
558 | if (ret) { | |
080eb83f | 559 | __memset(ret, KASAN_SHADOW_INIT, shadow_size); |
bffa986c AK |
560 | find_vm_area(addr)->flags |= VM_KASAN; |
561 | kmemleak_ignore(ret); | |
562 | return 0; | |
563 | } | |
564 | ||
565 | return -ENOMEM; | |
566 | } | |
567 | ||
568 | void kasan_free_shadow(const struct vm_struct *vm) | |
569 | { | |
570 | if (vm->flags & VM_KASAN) | |
571 | vfree(kasan_mem_to_shadow(vm->addr)); | |
572 | } | |
573 | ||
574 | #ifdef CONFIG_MEMORY_HOTPLUG | |
575 | static bool shadow_mapped(unsigned long addr) | |
576 | { | |
577 | pgd_t *pgd = pgd_offset_k(addr); | |
578 | p4d_t *p4d; | |
579 | pud_t *pud; | |
580 | pmd_t *pmd; | |
581 | pte_t *pte; | |
582 | ||
583 | if (pgd_none(*pgd)) | |
584 | return false; | |
585 | p4d = p4d_offset(pgd, addr); | |
586 | if (p4d_none(*p4d)) | |
587 | return false; | |
588 | pud = pud_offset(p4d, addr); | |
589 | if (pud_none(*pud)) | |
590 | return false; | |
591 | ||
592 | /* | |
593 | * We can't use pud_large() or pud_huge(), the first one is | |
594 | * arch-specific, the last one depends on HUGETLB_PAGE. So let's abuse | |
595 | * pud_bad(), if pud is bad then it's bad because it's huge. | |
596 | */ | |
597 | if (pud_bad(*pud)) | |
598 | return true; | |
599 | pmd = pmd_offset(pud, addr); | |
600 | if (pmd_none(*pmd)) | |
601 | return false; | |
602 | ||
603 | if (pmd_bad(*pmd)) | |
604 | return true; | |
605 | pte = pte_offset_kernel(pmd, addr); | |
606 | return !pte_none(*pte); | |
607 | } | |
608 | ||
609 | static int __meminit kasan_mem_notifier(struct notifier_block *nb, | |
610 | unsigned long action, void *data) | |
611 | { | |
612 | struct memory_notify *mem_data = data; | |
613 | unsigned long nr_shadow_pages, start_kaddr, shadow_start; | |
614 | unsigned long shadow_end, shadow_size; | |
615 | ||
616 | nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT; | |
617 | start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn); | |
618 | shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr); | |
619 | shadow_size = nr_shadow_pages << PAGE_SHIFT; | |
620 | shadow_end = shadow_start + shadow_size; | |
621 | ||
622 | if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) || | |
623 | WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT))) | |
624 | return NOTIFY_BAD; | |
625 | ||
626 | switch (action) { | |
627 | case MEM_GOING_ONLINE: { | |
628 | void *ret; | |
629 | ||
630 | /* | |
631 | * If shadow is mapped already than it must have been mapped | |
632 | * during the boot. This could happen if we onlining previously | |
633 | * offlined memory. | |
634 | */ | |
635 | if (shadow_mapped(shadow_start)) | |
636 | return NOTIFY_OK; | |
637 | ||
638 | ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start, | |
639 | shadow_end, GFP_KERNEL, | |
640 | PAGE_KERNEL, VM_NO_GUARD, | |
641 | pfn_to_nid(mem_data->start_pfn), | |
642 | __builtin_return_address(0)); | |
643 | if (!ret) | |
644 | return NOTIFY_BAD; | |
645 | ||
646 | kmemleak_ignore(ret); | |
647 | return NOTIFY_OK; | |
648 | } | |
649 | case MEM_CANCEL_ONLINE: | |
650 | case MEM_OFFLINE: { | |
651 | struct vm_struct *vm; | |
652 | ||
653 | /* | |
654 | * shadow_start was either mapped during boot by kasan_init() | |
655 | * or during memory online by __vmalloc_node_range(). | |
656 | * In the latter case we can use vfree() to free shadow. | |
657 | * Non-NULL result of the find_vm_area() will tell us if | |
658 | * that was the second case. | |
659 | * | |
660 | * Currently it's not possible to free shadow mapped | |
661 | * during boot by kasan_init(). It's because the code | |
662 | * to do that hasn't been written yet. So we'll just | |
663 | * leak the memory. | |
664 | */ | |
665 | vm = find_vm_area((void *)shadow_start); | |
666 | if (vm) | |
667 | vfree((void *)shadow_start); | |
668 | } | |
669 | } | |
670 | ||
671 | return NOTIFY_OK; | |
672 | } | |
673 | ||
674 | static int __init kasan_memhotplug_init(void) | |
675 | { | |
676 | hotplug_memory_notifier(kasan_mem_notifier, 0); | |
677 | ||
678 | return 0; | |
679 | } | |
680 | ||
681 | core_initcall(kasan_memhotplug_init); | |
682 | #endif |