1 // SPDX-License-Identifier: GPL-2.0
2 #define DISABLE_BRANCH_PROFILING
3 #define pr_fmt(fmt) "kasan: " fmt
4 #include <linux/bootmem.h>
5 #include <linux/kasan.h>
6 #include <linux/kdebug.h>
7 #include <linux/memblock.h>
8 #include <linux/mm.h>
9 #include <linux/sched.h>
10 #include <linux/sched/task.h>
11 #include <linux/vmalloc.h>
12
13 #include <asm/e820/types.h>
14 #include <asm/pgalloc.h>
15 #include <asm/tlbflush.h>
16 #include <asm/sections.h>
17 #include <asm/pgtable.h>
18 #include <asm/cpu_entry_area.h>
19
20 extern struct range pfn_mapped[E820_MAX_ENTRIES];
21
22 static p4d_t tmp_p4d_table[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
23
early_alloc(size_t size,int nid,bool panic)24 static __init void *early_alloc(size_t size, int nid, bool panic)
25 {
26 if (panic)
27 return memblock_virt_alloc_try_nid(size, size,
28 __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
29 else
30 return memblock_virt_alloc_try_nid_nopanic(size, size,
31 __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
32 }
33
kasan_populate_pmd(pmd_t * pmd,unsigned long addr,unsigned long end,int nid)34 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
35 unsigned long end, int nid)
36 {
37 pte_t *pte;
38
39 if (pmd_none(*pmd)) {
40 void *p;
41
42 if (boot_cpu_has(X86_FEATURE_PSE) &&
43 ((end - addr) == PMD_SIZE) &&
44 IS_ALIGNED(addr, PMD_SIZE)) {
45 p = early_alloc(PMD_SIZE, nid, false);
46 if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
47 return;
48 else if (p)
49 memblock_free(__pa(p), PMD_SIZE);
50 }
51
52 p = early_alloc(PAGE_SIZE, nid, true);
53 pmd_populate_kernel(&init_mm, pmd, p);
54 }
55
56 pte = pte_offset_kernel(pmd, addr);
57 do {
58 pte_t entry;
59 void *p;
60
61 if (!pte_none(*pte))
62 continue;
63
64 p = early_alloc(PAGE_SIZE, nid, true);
65 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
66 set_pte_at(&init_mm, addr, pte, entry);
67 } while (pte++, addr += PAGE_SIZE, addr != end);
68 }
69
kasan_populate_pud(pud_t * pud,unsigned long addr,unsigned long end,int nid)70 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
71 unsigned long end, int nid)
72 {
73 pmd_t *pmd;
74 unsigned long next;
75
76 if (pud_none(*pud)) {
77 void *p;
78
79 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
80 ((end - addr) == PUD_SIZE) &&
81 IS_ALIGNED(addr, PUD_SIZE)) {
82 p = early_alloc(PUD_SIZE, nid, false);
83 if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
84 return;
85 else if (p)
86 memblock_free(__pa(p), PUD_SIZE);
87 }
88
89 p = early_alloc(PAGE_SIZE, nid, true);
90 pud_populate(&init_mm, pud, p);
91 }
92
93 pmd = pmd_offset(pud, addr);
94 do {
95 next = pmd_addr_end(addr, end);
96 if (!pmd_large(*pmd))
97 kasan_populate_pmd(pmd, addr, next, nid);
98 } while (pmd++, addr = next, addr != end);
99 }
100
kasan_populate_p4d(p4d_t * p4d,unsigned long addr,unsigned long end,int nid)101 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
102 unsigned long end, int nid)
103 {
104 pud_t *pud;
105 unsigned long next;
106
107 if (p4d_none(*p4d)) {
108 void *p = early_alloc(PAGE_SIZE, nid, true);
109
110 p4d_populate(&init_mm, p4d, p);
111 }
112
113 pud = pud_offset(p4d, addr);
114 do {
115 next = pud_addr_end(addr, end);
116 if (!pud_large(*pud))
117 kasan_populate_pud(pud, addr, next, nid);
118 } while (pud++, addr = next, addr != end);
119 }
120
kasan_populate_pgd(pgd_t * pgd,unsigned long addr,unsigned long end,int nid)121 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
122 unsigned long end, int nid)
123 {
124 void *p;
125 p4d_t *p4d;
126 unsigned long next;
127
128 if (pgd_none(*pgd)) {
129 p = early_alloc(PAGE_SIZE, nid, true);
130 pgd_populate(&init_mm, pgd, p);
131 }
132
133 p4d = p4d_offset(pgd, addr);
134 do {
135 next = p4d_addr_end(addr, end);
136 kasan_populate_p4d(p4d, addr, next, nid);
137 } while (p4d++, addr = next, addr != end);
138 }
139
kasan_populate_shadow(unsigned long addr,unsigned long end,int nid)140 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
141 int nid)
142 {
143 pgd_t *pgd;
144 unsigned long next;
145
146 addr = addr & PAGE_MASK;
147 end = round_up(end, PAGE_SIZE);
148 pgd = pgd_offset_k(addr);
149 do {
150 next = pgd_addr_end(addr, end);
151 kasan_populate_pgd(pgd, addr, next, nid);
152 } while (pgd++, addr = next, addr != end);
153 }
154
map_range(struct range * range)155 static void __init map_range(struct range *range)
156 {
157 unsigned long start;
158 unsigned long end;
159
160 start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
161 end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
162
163 kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
164 }
165
clear_pgds(unsigned long start,unsigned long end)166 static void __init clear_pgds(unsigned long start,
167 unsigned long end)
168 {
169 pgd_t *pgd;
170 /* See comment in kasan_init() */
171 unsigned long pgd_end = end & PGDIR_MASK;
172
173 for (; start < pgd_end; start += PGDIR_SIZE) {
174 pgd = pgd_offset_k(start);
175 /*
176 * With folded p4d, pgd_clear() is nop, use p4d_clear()
177 * instead.
178 */
179 if (CONFIG_PGTABLE_LEVELS < 5)
180 p4d_clear(p4d_offset(pgd, start));
181 else
182 pgd_clear(pgd);
183 }
184
185 pgd = pgd_offset_k(start);
186 for (; start < end; start += P4D_SIZE)
187 p4d_clear(p4d_offset(pgd, start));
188 }
189
early_p4d_offset(pgd_t * pgd,unsigned long addr)190 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
191 {
192 unsigned long p4d;
193
194 if (!IS_ENABLED(CONFIG_X86_5LEVEL))
195 return (p4d_t *)pgd;
196
197 p4d = pgd_val(*pgd) & PTE_PFN_MASK;
198 p4d += __START_KERNEL_map - phys_base;
199 return (p4d_t *)p4d + p4d_index(addr);
200 }
201
kasan_early_p4d_populate(pgd_t * pgd,unsigned long addr,unsigned long end)202 static void __init kasan_early_p4d_populate(pgd_t *pgd,
203 unsigned long addr,
204 unsigned long end)
205 {
206 pgd_t pgd_entry;
207 p4d_t *p4d, p4d_entry;
208 unsigned long next;
209
210 if (pgd_none(*pgd)) {
211 pgd_entry = __pgd(_KERNPG_TABLE | __pa_nodebug(kasan_zero_p4d));
212 set_pgd(pgd, pgd_entry);
213 }
214
215 p4d = early_p4d_offset(pgd, addr);
216 do {
217 next = p4d_addr_end(addr, end);
218
219 if (!p4d_none(*p4d))
220 continue;
221
222 p4d_entry = __p4d(_KERNPG_TABLE | __pa_nodebug(kasan_zero_pud));
223 set_p4d(p4d, p4d_entry);
224 } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
225 }
226
kasan_map_early_shadow(pgd_t * pgd)227 static void __init kasan_map_early_shadow(pgd_t *pgd)
228 {
229 /* See comment in kasan_init() */
230 unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
231 unsigned long end = KASAN_SHADOW_END;
232 unsigned long next;
233
234 pgd += pgd_index(addr);
235 do {
236 next = pgd_addr_end(addr, end);
237 kasan_early_p4d_populate(pgd, addr, next);
238 } while (pgd++, addr = next, addr != end);
239 }
240
241 #ifdef CONFIG_KASAN_INLINE
kasan_die_handler(struct notifier_block * self,unsigned long val,void * data)242 static int kasan_die_handler(struct notifier_block *self,
243 unsigned long val,
244 void *data)
245 {
246 if (val == DIE_GPF) {
247 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
248 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
249 }
250 return NOTIFY_OK;
251 }
252
253 static struct notifier_block kasan_die_notifier = {
254 .notifier_call = kasan_die_handler,
255 };
256 #endif
257
kasan_early_init(void)258 void __init kasan_early_init(void)
259 {
260 int i;
261 pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL | _PAGE_ENC;
262 pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
263 pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
264 p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
265
266 for (i = 0; i < PTRS_PER_PTE; i++)
267 kasan_zero_pte[i] = __pte(pte_val);
268
269 for (i = 0; i < PTRS_PER_PMD; i++)
270 kasan_zero_pmd[i] = __pmd(pmd_val);
271
272 for (i = 0; i < PTRS_PER_PUD; i++)
273 kasan_zero_pud[i] = __pud(pud_val);
274
275 for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++)
276 kasan_zero_p4d[i] = __p4d(p4d_val);
277
278 kasan_map_early_shadow(early_top_pgt);
279 kasan_map_early_shadow(init_top_pgt);
280 }
281
kasan_init(void)282 void __init kasan_init(void)
283 {
284 int i;
285 void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
286
287 #ifdef CONFIG_KASAN_INLINE
288 register_die_notifier(&kasan_die_notifier);
289 #endif
290
291 memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
292
293 /*
294 * We use the same shadow offset for 4- and 5-level paging to
295 * facilitate boot-time switching between paging modes.
296 * As result in 5-level paging mode KASAN_SHADOW_START and
297 * KASAN_SHADOW_END are not aligned to PGD boundary.
298 *
299 * KASAN_SHADOW_START doesn't share PGD with anything else.
300 * We claim whole PGD entry to make things easier.
301 *
302 * KASAN_SHADOW_END lands in the last PGD entry and it collides with
303 * bunch of things like kernel code, modules, EFI mapping, etc.
304 * We need to take extra steps to not overwrite them.
305 */
306 if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
307 void *ptr;
308
309 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
310 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
311 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
312 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
313 }
314
315 load_cr3(early_top_pgt);
316 __flush_tlb_all();
317
318 clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
319
320 kasan_populate_zero_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
321 kasan_mem_to_shadow((void *)PAGE_OFFSET));
322
323 for (i = 0; i < E820_MAX_ENTRIES; i++) {
324 if (pfn_mapped[i].end == 0)
325 break;
326
327 map_range(&pfn_mapped[i]);
328 }
329
330 shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
331 shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
332 shadow_cpu_entry_begin = (void *)round_down((unsigned long)shadow_cpu_entry_begin,
333 PAGE_SIZE);
334
335 shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
336 CPU_ENTRY_AREA_MAP_SIZE);
337 shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
338 shadow_cpu_entry_end = (void *)round_up((unsigned long)shadow_cpu_entry_end,
339 PAGE_SIZE);
340
341 kasan_populate_zero_shadow(
342 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
343 shadow_cpu_entry_begin);
344
345 kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
346 (unsigned long)shadow_cpu_entry_end, 0);
347
348 kasan_populate_zero_shadow(shadow_cpu_entry_end,
349 kasan_mem_to_shadow((void *)__START_KERNEL_map));
350
351 kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
352 (unsigned long)kasan_mem_to_shadow(_end),
353 early_pfn_to_nid(__pa(_stext)));
354
355 kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
356 (void *)KASAN_SHADOW_END);
357
358 load_cr3(init_top_pgt);
359 __flush_tlb_all();
360
361 /*
362 * kasan_zero_page has been used as early shadow memory, thus it may
363 * contain some garbage. Now we can clear and write protect it, since
364 * after the TLB flush no one should write to it.
365 */
366 memset(kasan_zero_page, 0, PAGE_SIZE);
367 for (i = 0; i < PTRS_PER_PTE; i++) {
368 pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO | _PAGE_ENC);
369 set_pte(&kasan_zero_pte[i], pte);
370 }
371 /* Flush TLBs again to be sure that write protection applied. */
372 __flush_tlb_all();
373
374 init_task.kasan_depth = 0;
375 pr_info("KernelAddressSanitizer initialized\n");
376 }
377