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TOMOYO Linux Cross Reference
Linux/arch/x86/mm/kasan_init_64.c

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  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 
 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 
 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 
 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 
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 
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 
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 
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 
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 
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 = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
198         p4d += __START_KERNEL_map - phys_base;
199         return (p4d_t *)p4d + p4d_index(addr);
200 }
201 
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 
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
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 
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 
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 

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