1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * KMSAN API for subsystems.
4 *
5 * Copyright (C) 2017-2022 Google LLC
6 * Author: Alexander Potapenko <glider@google.com>
7 *
8 */
9 #ifndef _LINUX_KMSAN_H
10 #define _LINUX_KMSAN_H
11
12 #include <linux/dma-direction.h>
13 #include <linux/gfp.h>
14 #include <linux/kmsan-checks.h>
15 #include <linux/types.h>
16
17 struct page;
18 struct kmem_cache;
19 struct task_struct;
20 struct scatterlist;
21 struct urb;
22
23 #ifdef CONFIG_KMSAN
24
25 /**
26 * kmsan_task_create() - Initialize KMSAN state for the task.
27 * @task: task to initialize.
28 */
29 void kmsan_task_create(struct task_struct *task);
30
31 /**
32 * kmsan_task_exit() - Notify KMSAN that a task has exited.
33 * @task: task about to finish.
34 */
35 void kmsan_task_exit(struct task_struct *task);
36
37 /**
38 * kmsan_init_shadow() - Initialize KMSAN shadow at boot time.
39 *
40 * Allocate and initialize KMSAN metadata for early allocations.
41 */
42 void __init kmsan_init_shadow(void);
43
44 /**
45 * kmsan_init_runtime() - Initialize KMSAN state and enable KMSAN.
46 */
47 void __init kmsan_init_runtime(void);
48
49 /**
50 * kmsan_memblock_free_pages() - handle freeing of memblock pages.
51 * @page: struct page to free.
52 * @order: order of @page.
53 *
54 * Freed pages are either returned to buddy allocator or held back to be used
55 * as metadata pages.
56 */
57 bool __init __must_check kmsan_memblock_free_pages(struct page *page,
58 unsigned int order);
59
60 /**
61 * kmsan_alloc_page() - Notify KMSAN about an alloc_pages() call.
62 * @page: struct page pointer returned by alloc_pages().
63 * @order: order of allocated struct page.
64 * @flags: GFP flags used by alloc_pages()
65 *
66 * KMSAN marks 1<<@order pages starting at @page as uninitialized, unless
67 * @flags contain __GFP_ZERO.
68 */
69 void kmsan_alloc_page(struct page *page, unsigned int order, gfp_t flags);
70
71 /**
72 * kmsan_free_page() - Notify KMSAN about a free_pages() call.
73 * @page: struct page pointer passed to free_pages().
74 * @order: order of deallocated struct page.
75 *
76 * KMSAN marks freed memory as uninitialized.
77 */
78 void kmsan_free_page(struct page *page, unsigned int order);
79
80 /**
81 * kmsan_copy_page_meta() - Copy KMSAN metadata between two pages.
82 * @dst: destination page.
83 * @src: source page.
84 *
85 * KMSAN copies the contents of metadata pages for @src into the metadata pages
86 * for @dst. If @dst has no associated metadata pages, nothing happens.
87 * If @src has no associated metadata pages, @dst metadata pages are unpoisoned.
88 */
89 void kmsan_copy_page_meta(struct page *dst, struct page *src);
90
91 /**
92 * kmsan_slab_alloc() - Notify KMSAN about a slab allocation.
93 * @s: slab cache the object belongs to.
94 * @object: object pointer.
95 * @flags: GFP flags passed to the allocator.
96 *
97 * Depending on cache flags and GFP flags, KMSAN sets up the metadata of the
98 * newly created object, marking it as initialized or uninitialized.
99 */
100 void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
101
102 /**
103 * kmsan_slab_free() - Notify KMSAN about a slab deallocation.
104 * @s: slab cache the object belongs to.
105 * @object: object pointer.
106 *
107 * KMSAN marks the freed object as uninitialized.
108 */
109 void kmsan_slab_free(struct kmem_cache *s, void *object);
110
111 /**
112 * kmsan_kmalloc_large() - Notify KMSAN about a large slab allocation.
113 * @ptr: object pointer.
114 * @size: object size.
115 * @flags: GFP flags passed to the allocator.
116 *
117 * Similar to kmsan_slab_alloc(), but for large allocations.
118 */
119 void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
120
121 /**
122 * kmsan_kfree_large() - Notify KMSAN about a large slab deallocation.
123 * @ptr: object pointer.
124 *
125 * Similar to kmsan_slab_free(), but for large allocations.
126 */
127 void kmsan_kfree_large(const void *ptr);
128
129 /**
130 * kmsan_map_kernel_range_noflush() - Notify KMSAN about a vmap.
131 * @start: start of vmapped range.
132 * @end: end of vmapped range.
133 * @prot: page protection flags used for vmap.
134 * @pages: array of pages.
135 * @page_shift: page_shift passed to vmap_range_noflush().
136 * @gfp_mask: gfp_mask to use internally.
137 *
138 * KMSAN maps shadow and origin pages of @pages into contiguous ranges in
139 * vmalloc metadata address range. Returns 0 on success, callers must check
140 * for non-zero return value.
141 */
142 int __must_check kmsan_vmap_pages_range_noflush(unsigned long start,
143 unsigned long end,
144 pgprot_t prot,
145 struct page **pages,
146 unsigned int page_shift,
147 gfp_t gfp_mask);
148
149 /**
150 * kmsan_vunmap_kernel_range_noflush() - Notify KMSAN about a vunmap.
151 * @start: start of vunmapped range.
152 * @end: end of vunmapped range.
153 *
154 * KMSAN unmaps the contiguous metadata ranges created by
155 * kmsan_map_kernel_range_noflush().
156 */
157 void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end);
158
159 /**
160 * kmsan_ioremap_page_range() - Notify KMSAN about a ioremap_page_range() call.
161 * @addr: range start.
162 * @end: range end.
163 * @phys_addr: physical range start.
164 * @prot: page protection flags used for ioremap_page_range().
165 * @page_shift: page_shift argument passed to vmap_range_noflush().
166 *
167 * KMSAN creates new metadata pages for the physical pages mapped into the
168 * virtual memory. Returns 0 on success, callers must check for non-zero return
169 * value.
170 */
171 int __must_check kmsan_ioremap_page_range(unsigned long addr, unsigned long end,
172 phys_addr_t phys_addr, pgprot_t prot,
173 unsigned int page_shift);
174
175 /**
176 * kmsan_iounmap_page_range() - Notify KMSAN about a iounmap_page_range() call.
177 * @start: range start.
178 * @end: range end.
179 *
180 * KMSAN unmaps the metadata pages for the given range and, unlike for
181 * vunmap_page_range(), also deallocates them.
182 */
183 void kmsan_iounmap_page_range(unsigned long start, unsigned long end);
184
185 /**
186 * kmsan_handle_dma() - Handle a DMA data transfer.
187 * @phys: physical address of the buffer.
188 * @size: buffer size.
189 * @dir: one of possible dma_data_direction values.
190 *
191 * Depending on @direction, KMSAN:
192 * * checks the buffer, if it is copied to device;
193 * * initializes the buffer, if it is copied from device;
194 * * does both, if this is a DMA_BIDIRECTIONAL transfer.
195 */
196 void kmsan_handle_dma(phys_addr_t phys, size_t size,
197 enum dma_data_direction dir);
198
199 /**
200 * kmsan_handle_dma_sg() - Handle a DMA transfer using scatterlist.
201 * @sg: scatterlist holding DMA buffers.
202 * @nents: number of scatterlist entries.
203 * @dir: one of possible dma_data_direction values.
204 *
205 * Depending on @direction, KMSAN:
206 * * checks the buffers in the scatterlist, if they are copied to device;
207 * * initializes the buffers, if they are copied from device;
208 * * does both, if this is a DMA_BIDIRECTIONAL transfer.
209 */
210 void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
211 enum dma_data_direction dir);
212
213 /**
214 * kmsan_handle_urb() - Handle a USB data transfer.
215 * @urb: struct urb pointer.
216 * @is_out: data transfer direction (true means output to hardware).
217 *
218 * If @is_out is true, KMSAN checks the transfer buffer of @urb. Otherwise,
219 * KMSAN initializes the transfer buffer.
220 */
221 void kmsan_handle_urb(const struct urb *urb, bool is_out);
222
223 /**
224 * kmsan_unpoison_entry_regs() - Handle pt_regs in low-level entry code.
225 * @regs: struct pt_regs pointer received from assembly code.
226 *
227 * KMSAN unpoisons the contents of the passed pt_regs, preventing potential
228 * false positive reports. Unlike kmsan_unpoison_memory(),
229 * kmsan_unpoison_entry_regs() can be called from the regions where
230 * kmsan_in_runtime() returns true, which is the case in early entry code.
231 */
232 void kmsan_unpoison_entry_regs(const struct pt_regs *regs);
233
234 /**
235 * kmsan_get_metadata() - Return a pointer to KMSAN shadow or origins.
236 * @addr: kernel address.
237 * @is_origin: whether to return origins or shadow.
238 *
239 * Return NULL if metadata cannot be found.
240 */
241 void *kmsan_get_metadata(void *addr, bool is_origin);
242
243 /**
244 * kmsan_enable_current(): Enable KMSAN for the current task.
245 *
246 * Each kmsan_enable_current() current call must be preceded by a
247 * kmsan_disable_current() call. These call pairs may be nested.
248 */
249 void kmsan_enable_current(void);
250
251 /**
252 * kmsan_disable_current(): Disable KMSAN for the current task.
253 *
254 * Each kmsan_disable_current() current call must be followed by a
255 * kmsan_enable_current() call. These call pairs may be nested.
256 */
257 void kmsan_disable_current(void);
258
259 /**
260 * memset_no_sanitize_memory(): Fill memory without KMSAN instrumentation.
261 * @s: address of kernel memory to fill.
262 * @c: constant byte to fill the memory with.
263 * @n: number of bytes to fill.
264 *
265 * This is like memset(), but without KMSAN instrumentation.
266 */
memset_no_sanitize_memory(void * s,int c,size_t n)267 static inline void *memset_no_sanitize_memory(void *s, int c, size_t n)
268 {
269 return __memset(s, c, n);
270 }
271
272 extern bool kmsan_enabled;
273 extern int panic_on_kmsan;
274
275 /*
276 * KMSAN performs a lot of consistency checks that are currently enabled by
277 * default. BUG_ON is normally discouraged in the kernel, unless used for
278 * debugging, but KMSAN itself is a debugging tool, so it makes little sense to
279 * recover if something goes wrong.
280 */
281 #define KMSAN_WARN_ON(cond) \
282 ({ \
283 const bool __cond = WARN_ON(cond); \
284 if (unlikely(__cond)) { \
285 WRITE_ONCE(kmsan_enabled, false); \
286 if (panic_on_kmsan) { \
287 /* Can't call panic() here because */ \
288 /* of uaccess checks. */ \
289 BUG(); \
290 } \
291 } \
292 __cond; \
293 })
294
295 #else
296
kmsan_init_shadow(void)297 static inline void kmsan_init_shadow(void)
298 {
299 }
300
kmsan_init_runtime(void)301 static inline void kmsan_init_runtime(void)
302 {
303 }
304
kmsan_memblock_free_pages(struct page * page,unsigned int order)305 static inline bool __must_check kmsan_memblock_free_pages(struct page *page,
306 unsigned int order)
307 {
308 return true;
309 }
310
kmsan_task_create(struct task_struct * task)311 static inline void kmsan_task_create(struct task_struct *task)
312 {
313 }
314
kmsan_task_exit(struct task_struct * task)315 static inline void kmsan_task_exit(struct task_struct *task)
316 {
317 }
318
kmsan_alloc_page(struct page * page,unsigned int order,gfp_t flags)319 static inline void kmsan_alloc_page(struct page *page, unsigned int order,
320 gfp_t flags)
321 {
322 }
323
kmsan_free_page(struct page * page,unsigned int order)324 static inline void kmsan_free_page(struct page *page, unsigned int order)
325 {
326 }
327
kmsan_copy_page_meta(struct page * dst,struct page * src)328 static inline void kmsan_copy_page_meta(struct page *dst, struct page *src)
329 {
330 }
331
kmsan_slab_alloc(struct kmem_cache * s,void * object,gfp_t flags)332 static inline void kmsan_slab_alloc(struct kmem_cache *s, void *object,
333 gfp_t flags)
334 {
335 }
336
kmsan_slab_free(struct kmem_cache * s,void * object)337 static inline void kmsan_slab_free(struct kmem_cache *s, void *object)
338 {
339 }
340
kmsan_kmalloc_large(const void * ptr,size_t size,gfp_t flags)341 static inline void kmsan_kmalloc_large(const void *ptr, size_t size,
342 gfp_t flags)
343 {
344 }
345
kmsan_kfree_large(const void * ptr)346 static inline void kmsan_kfree_large(const void *ptr)
347 {
348 }
349
kmsan_vmap_pages_range_noflush(unsigned long start,unsigned long end,pgprot_t prot,struct page ** pages,unsigned int page_shift,gfp_t gfp_mask)350 static inline int __must_check kmsan_vmap_pages_range_noflush(
351 unsigned long start, unsigned long end, pgprot_t prot,
352 struct page **pages, unsigned int page_shift, gfp_t gfp_mask)
353 {
354 return 0;
355 }
356
kmsan_vunmap_range_noflush(unsigned long start,unsigned long end)357 static inline void kmsan_vunmap_range_noflush(unsigned long start,
358 unsigned long end)
359 {
360 }
361
kmsan_ioremap_page_range(unsigned long start,unsigned long end,phys_addr_t phys_addr,pgprot_t prot,unsigned int page_shift)362 static inline int __must_check kmsan_ioremap_page_range(unsigned long start,
363 unsigned long end,
364 phys_addr_t phys_addr,
365 pgprot_t prot,
366 unsigned int page_shift)
367 {
368 return 0;
369 }
370
kmsan_iounmap_page_range(unsigned long start,unsigned long end)371 static inline void kmsan_iounmap_page_range(unsigned long start,
372 unsigned long end)
373 {
374 }
375
kmsan_handle_dma(phys_addr_t phys,size_t size,enum dma_data_direction dir)376 static inline void kmsan_handle_dma(phys_addr_t phys, size_t size,
377 enum dma_data_direction dir)
378 {
379 }
380
kmsan_handle_dma_sg(struct scatterlist * sg,int nents,enum dma_data_direction dir)381 static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents,
382 enum dma_data_direction dir)
383 {
384 }
385
kmsan_handle_urb(const struct urb * urb,bool is_out)386 static inline void kmsan_handle_urb(const struct urb *urb, bool is_out)
387 {
388 }
389
kmsan_unpoison_entry_regs(const struct pt_regs * regs)390 static inline void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
391 {
392 }
393
kmsan_enable_current(void)394 static inline void kmsan_enable_current(void)
395 {
396 }
397
kmsan_disable_current(void)398 static inline void kmsan_disable_current(void)
399 {
400 }
401
memset_no_sanitize_memory(void * s,int c,size_t n)402 static inline void *memset_no_sanitize_memory(void *s, int c, size_t n)
403 {
404 return memset(s, c, n);
405 }
406
407 #define KMSAN_WARN_ON WARN_ON
408
409 #endif
410
411 #endif /* _LINUX_KMSAN_H */
412