1 // SPDX-License-Identifier: GPL-2.0
2 #define DISABLE_BRANCH_PROFILING
3 #define pr_fmt(fmt) "kasan: " fmt
4
5 /* cpu_feature_enabled() cannot be used this early */
6 #define USE_EARLY_PGTABLE_L5
7
8 #include <linux/memblock.h>
9 #include <linux/kasan.h>
10 #include <linux/kdebug.h>
11 #include <linux/mm.h>
12 #include <linux/sched.h>
13 #include <linux/sched/task.h>
14 #include <linux/vmalloc.h>
15
16 #include <asm/e820/types.h>
17 #include <asm/pgalloc.h>
18 #include <asm/tlbflush.h>
19 #include <asm/sections.h>
20 #include <asm/cpu_entry_area.h>
21
22 extern struct range pfn_mapped[E820_MAX_ENTRIES];
23
24 static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
25
early_alloc(size_t size,int nid,bool should_panic)26 static __init void *early_alloc(size_t size, int nid, bool should_panic)
27 {
28 void *ptr = memblock_alloc_try_nid(size, size,
29 __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
30
31 if (!ptr && should_panic)
32 panic("%pS: Failed to allocate page, nid=%d from=%lx\n",
33 (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS));
34
35 return ptr;
36 }
37
kasan_populate_pmd(pmd_t * pmd,unsigned long addr,unsigned long end,int nid)38 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
39 unsigned long end, int nid)
40 {
41 pte_t *pte;
42
43 if (pmd_none(*pmd)) {
44 void *p;
45
46 if (boot_cpu_has(X86_FEATURE_PSE) &&
47 ((end - addr) == PMD_SIZE) &&
48 IS_ALIGNED(addr, PMD_SIZE)) {
49 p = early_alloc(PMD_SIZE, nid, false);
50 if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
51 return;
52 else if (p)
53 memblock_free(__pa(p), PMD_SIZE);
54 }
55
56 p = early_alloc(PAGE_SIZE, nid, true);
57 pmd_populate_kernel(&init_mm, pmd, p);
58 }
59
60 pte = pte_offset_kernel(pmd, addr);
61 do {
62 pte_t entry;
63 void *p;
64
65 if (!pte_none(*pte))
66 continue;
67
68 p = early_alloc(PAGE_SIZE, nid, true);
69 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
70 set_pte_at(&init_mm, addr, pte, entry);
71 } while (pte++, addr += PAGE_SIZE, addr != end);
72 }
73
kasan_populate_pud(pud_t * pud,unsigned long addr,unsigned long end,int nid)74 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
75 unsigned long end, int nid)
76 {
77 pmd_t *pmd;
78 unsigned long next;
79
80 if (pud_none(*pud)) {
81 void *p;
82
83 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
84 ((end - addr) == PUD_SIZE) &&
85 IS_ALIGNED(addr, PUD_SIZE)) {
86 p = early_alloc(PUD_SIZE, nid, false);
87 if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
88 return;
89 else if (p)
90 memblock_free(__pa(p), PUD_SIZE);
91 }
92
93 p = early_alloc(PAGE_SIZE, nid, true);
94 pud_populate(&init_mm, pud, p);
95 }
96
97 pmd = pmd_offset(pud, addr);
98 do {
99 next = pmd_addr_end(addr, end);
100 if (!pmd_large(*pmd))
101 kasan_populate_pmd(pmd, addr, next, nid);
102 } while (pmd++, addr = next, addr != end);
103 }
104
kasan_populate_p4d(p4d_t * p4d,unsigned long addr,unsigned long end,int nid)105 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
106 unsigned long end, int nid)
107 {
108 pud_t *pud;
109 unsigned long next;
110
111 if (p4d_none(*p4d)) {
112 void *p = early_alloc(PAGE_SIZE, nid, true);
113
114 p4d_populate(&init_mm, p4d, p);
115 }
116
117 pud = pud_offset(p4d, addr);
118 do {
119 next = pud_addr_end(addr, end);
120 if (!pud_large(*pud))
121 kasan_populate_pud(pud, addr, next, nid);
122 } while (pud++, addr = next, addr != end);
123 }
124
kasan_populate_pgd(pgd_t * pgd,unsigned long addr,unsigned long end,int nid)125 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
126 unsigned long end, int nid)
127 {
128 void *p;
129 p4d_t *p4d;
130 unsigned long next;
131
132 if (pgd_none(*pgd)) {
133 p = early_alloc(PAGE_SIZE, nid, true);
134 pgd_populate(&init_mm, pgd, p);
135 }
136
137 p4d = p4d_offset(pgd, addr);
138 do {
139 next = p4d_addr_end(addr, end);
140 kasan_populate_p4d(p4d, addr, next, nid);
141 } while (p4d++, addr = next, addr != end);
142 }
143
kasan_populate_shadow(unsigned long addr,unsigned long end,int nid)144 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
145 int nid)
146 {
147 pgd_t *pgd;
148 unsigned long next;
149
150 addr = addr & PAGE_MASK;
151 end = round_up(end, PAGE_SIZE);
152 pgd = pgd_offset_k(addr);
153 do {
154 next = pgd_addr_end(addr, end);
155 kasan_populate_pgd(pgd, addr, next, nid);
156 } while (pgd++, addr = next, addr != end);
157 }
158
map_range(struct range * range)159 static void __init map_range(struct range *range)
160 {
161 unsigned long start;
162 unsigned long end;
163
164 start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
165 end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
166
167 kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
168 }
169
clear_pgds(unsigned long start,unsigned long end)170 static void __init clear_pgds(unsigned long start,
171 unsigned long end)
172 {
173 pgd_t *pgd;
174 /* See comment in kasan_init() */
175 unsigned long pgd_end = end & PGDIR_MASK;
176
177 for (; start < pgd_end; start += PGDIR_SIZE) {
178 pgd = pgd_offset_k(start);
179 /*
180 * With folded p4d, pgd_clear() is nop, use p4d_clear()
181 * instead.
182 */
183 if (pgtable_l5_enabled())
184 pgd_clear(pgd);
185 else
186 p4d_clear(p4d_offset(pgd, start));
187 }
188
189 pgd = pgd_offset_k(start);
190 for (; start < end; start += P4D_SIZE)
191 p4d_clear(p4d_offset(pgd, start));
192 }
193
early_p4d_offset(pgd_t * pgd,unsigned long addr)194 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
195 {
196 unsigned long p4d;
197
198 if (!pgtable_l5_enabled())
199 return (p4d_t *)pgd;
200
201 p4d = pgd_val(*pgd) & PTE_PFN_MASK;
202 p4d += __START_KERNEL_map - phys_base;
203 return (p4d_t *)p4d + p4d_index(addr);
204 }
205
kasan_early_p4d_populate(pgd_t * pgd,unsigned long addr,unsigned long end)206 static void __init kasan_early_p4d_populate(pgd_t *pgd,
207 unsigned long addr,
208 unsigned long end)
209 {
210 pgd_t pgd_entry;
211 p4d_t *p4d, p4d_entry;
212 unsigned long next;
213
214 if (pgd_none(*pgd)) {
215 pgd_entry = __pgd(_KERNPG_TABLE |
216 __pa_nodebug(kasan_early_shadow_p4d));
217 set_pgd(pgd, pgd_entry);
218 }
219
220 p4d = early_p4d_offset(pgd, addr);
221 do {
222 next = p4d_addr_end(addr, end);
223
224 if (!p4d_none(*p4d))
225 continue;
226
227 p4d_entry = __p4d(_KERNPG_TABLE |
228 __pa_nodebug(kasan_early_shadow_pud));
229 set_p4d(p4d, p4d_entry);
230 } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
231 }
232
kasan_map_early_shadow(pgd_t * pgd)233 static void __init kasan_map_early_shadow(pgd_t *pgd)
234 {
235 /* See comment in kasan_init() */
236 unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
237 unsigned long end = KASAN_SHADOW_END;
238 unsigned long next;
239
240 pgd += pgd_index(addr);
241 do {
242 next = pgd_addr_end(addr, end);
243 kasan_early_p4d_populate(pgd, addr, next);
244 } while (pgd++, addr = next, addr != end);
245 }
246
kasan_shallow_populate_p4ds(pgd_t * pgd,unsigned long addr,unsigned long end)247 static void __init kasan_shallow_populate_p4ds(pgd_t *pgd,
248 unsigned long addr,
249 unsigned long end)
250 {
251 p4d_t *p4d;
252 unsigned long next;
253 void *p;
254
255 p4d = p4d_offset(pgd, addr);
256 do {
257 next = p4d_addr_end(addr, end);
258
259 if (p4d_none(*p4d)) {
260 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
261 p4d_populate(&init_mm, p4d, p);
262 }
263 } while (p4d++, addr = next, addr != end);
264 }
265
kasan_shallow_populate_pgds(void * start,void * end)266 static void __init kasan_shallow_populate_pgds(void *start, void *end)
267 {
268 unsigned long addr, next;
269 pgd_t *pgd;
270 void *p;
271
272 addr = (unsigned long)start;
273 pgd = pgd_offset_k(addr);
274 do {
275 next = pgd_addr_end(addr, (unsigned long)end);
276
277 if (pgd_none(*pgd)) {
278 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
279 pgd_populate(&init_mm, pgd, p);
280 }
281
282 /*
283 * we need to populate p4ds to be synced when running in
284 * four level mode - see sync_global_pgds_l4()
285 */
286 kasan_shallow_populate_p4ds(pgd, addr, next);
287 } while (pgd++, addr = next, addr != (unsigned long)end);
288 }
289
kasan_early_init(void)290 void __init kasan_early_init(void)
291 {
292 int i;
293 pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
294 __PAGE_KERNEL | _PAGE_ENC;
295 pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
296 pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
297 p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;
298
299 /* Mask out unsupported __PAGE_KERNEL bits: */
300 pte_val &= __default_kernel_pte_mask;
301 pmd_val &= __default_kernel_pte_mask;
302 pud_val &= __default_kernel_pte_mask;
303 p4d_val &= __default_kernel_pte_mask;
304
305 for (i = 0; i < PTRS_PER_PTE; i++)
306 kasan_early_shadow_pte[i] = __pte(pte_val);
307
308 for (i = 0; i < PTRS_PER_PMD; i++)
309 kasan_early_shadow_pmd[i] = __pmd(pmd_val);
310
311 for (i = 0; i < PTRS_PER_PUD; i++)
312 kasan_early_shadow_pud[i] = __pud(pud_val);
313
314 for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
315 kasan_early_shadow_p4d[i] = __p4d(p4d_val);
316
317 kasan_map_early_shadow(early_top_pgt);
318 kasan_map_early_shadow(init_top_pgt);
319 }
320
kasan_init(void)321 void __init kasan_init(void)
322 {
323 int i;
324 void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
325
326 memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
327
328 /*
329 * We use the same shadow offset for 4- and 5-level paging to
330 * facilitate boot-time switching between paging modes.
331 * As result in 5-level paging mode KASAN_SHADOW_START and
332 * KASAN_SHADOW_END are not aligned to PGD boundary.
333 *
334 * KASAN_SHADOW_START doesn't share PGD with anything else.
335 * We claim whole PGD entry to make things easier.
336 *
337 * KASAN_SHADOW_END lands in the last PGD entry and it collides with
338 * bunch of things like kernel code, modules, EFI mapping, etc.
339 * We need to take extra steps to not overwrite them.
340 */
341 if (pgtable_l5_enabled()) {
342 void *ptr;
343
344 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
345 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
346 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
347 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
348 }
349
350 load_cr3(early_top_pgt);
351 __flush_tlb_all();
352
353 clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
354
355 kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
356 kasan_mem_to_shadow((void *)PAGE_OFFSET));
357
358 for (i = 0; i < E820_MAX_ENTRIES; i++) {
359 if (pfn_mapped[i].end == 0)
360 break;
361
362 map_range(&pfn_mapped[i]);
363 }
364
365 shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
366 shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
367 shadow_cpu_entry_begin = (void *)round_down(
368 (unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);
369
370 shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
371 CPU_ENTRY_AREA_MAP_SIZE);
372 shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
373 shadow_cpu_entry_end = (void *)round_up(
374 (unsigned long)shadow_cpu_entry_end, PAGE_SIZE);
375
376 kasan_populate_early_shadow(
377 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
378 kasan_mem_to_shadow((void *)VMALLOC_START));
379
380 /*
381 * If we're in full vmalloc mode, don't back vmalloc space with early
382 * shadow pages. Instead, prepopulate pgds/p4ds so they are synced to
383 * the global table and we can populate the lower levels on demand.
384 */
385 if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
386 kasan_shallow_populate_pgds(
387 kasan_mem_to_shadow((void *)VMALLOC_START),
388 kasan_mem_to_shadow((void *)VMALLOC_END));
389 else
390 kasan_populate_early_shadow(
391 kasan_mem_to_shadow((void *)VMALLOC_START),
392 kasan_mem_to_shadow((void *)VMALLOC_END));
393
394 kasan_populate_early_shadow(
395 kasan_mem_to_shadow((void *)VMALLOC_END + 1),
396 shadow_cpu_entry_begin);
397
398 kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
399 (unsigned long)shadow_cpu_entry_end, 0);
400
401 kasan_populate_early_shadow(shadow_cpu_entry_end,
402 kasan_mem_to_shadow((void *)__START_KERNEL_map));
403
404 kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
405 (unsigned long)kasan_mem_to_shadow(_end),
406 early_pfn_to_nid(__pa(_stext)));
407
408 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
409 (void *)KASAN_SHADOW_END);
410
411 load_cr3(init_top_pgt);
412 __flush_tlb_all();
413
414 /*
415 * kasan_early_shadow_page has been used as early shadow memory, thus
416 * it may contain some garbage. Now we can clear and write protect it,
417 * since after the TLB flush no one should write to it.
418 */
419 memset(kasan_early_shadow_page, 0, PAGE_SIZE);
420 for (i = 0; i < PTRS_PER_PTE; i++) {
421 pte_t pte;
422 pgprot_t prot;
423
424 prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
425 pgprot_val(prot) &= __default_kernel_pte_mask;
426
427 pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
428 set_pte(&kasan_early_shadow_pte[i], pte);
429 }
430 /* Flush TLBs again to be sure that write protection applied. */
431 __flush_tlb_all();
432
433 init_task.kasan_depth = 0;
434 pr_info("KernelAddressSanitizer initialized\n");
435 }
436