1 /*
2 * mm/mprotect.c
3 *
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
9 */
10
11 #include <linux/mm.h>
12 #include <linux/hugetlb.h>
13 #include <linux/shm.h>
14 #include <linux/mman.h>
15 #include <linux/fs.h>
16 #include <linux/highmem.h>
17 #include <linux/security.h>
18 #include <linux/mempolicy.h>
19 #include <linux/personality.h>
20 #include <linux/syscalls.h>
21 #include <linux/swap.h>
22 #include <linux/swapops.h>
23 #include <linux/mmu_notifier.h>
24 #include <linux/migrate.h>
25 #include <linux/perf_event.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/cacheflush.h>
29 #include <asm/tlbflush.h>
30
31 #ifndef pgprot_modify
pgprot_modify(pgprot_t oldprot,pgprot_t newprot)32 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33 {
34 return newprot;
35 }
36 #endif
37
change_pte_range(struct vm_area_struct * vma,pmd_t * pmd,unsigned long addr,unsigned long end,pgprot_t newprot,int dirty_accountable,int prot_numa,bool * ret_all_same_node)38 static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable, int prot_numa, bool *ret_all_same_node)
41 {
42 struct mm_struct *mm = vma->vm_mm;
43 pte_t *pte, oldpte;
44 spinlock_t *ptl;
45 unsigned long pages = 0;
46 bool all_same_node = true;
47 int last_nid = -1;
48
49 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
50 arch_enter_lazy_mmu_mode();
51 do {
52 oldpte = *pte;
53 if (pte_present(oldpte)) {
54 pte_t ptent;
55 bool updated = false;
56
57 ptent = ptep_modify_prot_start(mm, addr, pte);
58 if (!prot_numa) {
59 ptent = pte_modify(ptent, newprot);
60 updated = true;
61 } else {
62 struct page *page;
63
64 page = vm_normal_page(vma, addr, oldpte);
65 if (page) {
66 int this_nid = page_to_nid(page);
67 if (last_nid == -1)
68 last_nid = this_nid;
69 if (last_nid != this_nid)
70 all_same_node = false;
71
72 /* only check non-shared pages */
73 if (!pte_numa(oldpte) &&
74 page_mapcount(page) == 1) {
75 ptent = pte_mknuma(ptent);
76 updated = true;
77 }
78 }
79 }
80
81 /*
82 * Avoid taking write faults for pages we know to be
83 * dirty.
84 */
85 if (dirty_accountable && pte_dirty(ptent)) {
86 ptent = pte_mkwrite(ptent);
87 updated = true;
88 }
89
90 if (updated)
91 pages++;
92 ptep_modify_prot_commit(mm, addr, pte, ptent);
93 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
94 swp_entry_t entry = pte_to_swp_entry(oldpte);
95
96 if (is_write_migration_entry(entry)) {
97 /*
98 * A protection check is difficult so
99 * just be safe and disable write
100 */
101 make_migration_entry_read(&entry);
102 set_pte_at(mm, addr, pte,
103 swp_entry_to_pte(entry));
104 }
105 pages++;
106 }
107 } while (pte++, addr += PAGE_SIZE, addr != end);
108 arch_leave_lazy_mmu_mode();
109 pte_unmap_unlock(pte - 1, ptl);
110
111 *ret_all_same_node = all_same_node;
112 return pages;
113 }
114
115 #ifdef CONFIG_NUMA_BALANCING
change_pmd_protnuma(struct mm_struct * mm,unsigned long addr,pmd_t * pmd)116 static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
117 pmd_t *pmd)
118 {
119 spin_lock(&mm->page_table_lock);
120 set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd));
121 spin_unlock(&mm->page_table_lock);
122 }
123 #else
change_pmd_protnuma(struct mm_struct * mm,unsigned long addr,pmd_t * pmd)124 static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr,
125 pmd_t *pmd)
126 {
127 BUG();
128 }
129 #endif /* CONFIG_NUMA_BALANCING */
130
change_pmd_range(struct vm_area_struct * vma,pud_t * pud,unsigned long addr,unsigned long end,pgprot_t newprot,int dirty_accountable,int prot_numa)131 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
132 pud_t *pud, unsigned long addr, unsigned long end,
133 pgprot_t newprot, int dirty_accountable, int prot_numa)
134 {
135 pmd_t *pmd;
136 unsigned long next;
137 unsigned long pages = 0;
138 bool all_same_node;
139
140 pmd = pmd_offset(pud, addr);
141 do {
142 next = pmd_addr_end(addr, end);
143 if (pmd_trans_huge(*pmd)) {
144 if (next - addr != HPAGE_PMD_SIZE)
145 split_huge_page_pmd(vma, addr, pmd);
146 else if (change_huge_pmd(vma, pmd, addr, newprot,
147 prot_numa)) {
148 pages += HPAGE_PMD_NR;
149 continue;
150 }
151 /* fall through */
152 }
153 if (pmd_none_or_clear_bad(pmd))
154 continue;
155 pages += change_pte_range(vma, pmd, addr, next, newprot,
156 dirty_accountable, prot_numa, &all_same_node);
157
158 /*
159 * If we are changing protections for NUMA hinting faults then
160 * set pmd_numa if the examined pages were all on the same
161 * node. This allows a regular PMD to be handled as one fault
162 * and effectively batches the taking of the PTL
163 */
164 if (prot_numa && all_same_node)
165 change_pmd_protnuma(vma->vm_mm, addr, pmd);
166 } while (pmd++, addr = next, addr != end);
167
168 return pages;
169 }
170
change_pud_range(struct vm_area_struct * vma,pgd_t * pgd,unsigned long addr,unsigned long end,pgprot_t newprot,int dirty_accountable,int prot_numa)171 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
172 pgd_t *pgd, unsigned long addr, unsigned long end,
173 pgprot_t newprot, int dirty_accountable, int prot_numa)
174 {
175 pud_t *pud;
176 unsigned long next;
177 unsigned long pages = 0;
178
179 pud = pud_offset(pgd, addr);
180 do {
181 next = pud_addr_end(addr, end);
182 if (pud_none_or_clear_bad(pud))
183 continue;
184 pages += change_pmd_range(vma, pud, addr, next, newprot,
185 dirty_accountable, prot_numa);
186 } while (pud++, addr = next, addr != end);
187
188 return pages;
189 }
190
change_protection_range(struct vm_area_struct * vma,unsigned long addr,unsigned long end,pgprot_t newprot,int dirty_accountable,int prot_numa)191 static unsigned long change_protection_range(struct vm_area_struct *vma,
192 unsigned long addr, unsigned long end, pgprot_t newprot,
193 int dirty_accountable, int prot_numa)
194 {
195 struct mm_struct *mm = vma->vm_mm;
196 pgd_t *pgd;
197 unsigned long next;
198 unsigned long start = addr;
199 unsigned long pages = 0;
200
201 BUG_ON(addr >= end);
202 pgd = pgd_offset(mm, addr);
203 flush_cache_range(vma, addr, end);
204 do {
205 next = pgd_addr_end(addr, end);
206 if (pgd_none_or_clear_bad(pgd))
207 continue;
208 pages += change_pud_range(vma, pgd, addr, next, newprot,
209 dirty_accountable, prot_numa);
210 } while (pgd++, addr = next, addr != end);
211
212 /* Only flush the TLB if we actually modified any entries: */
213 if (pages)
214 flush_tlb_range(vma, start, end);
215
216 return pages;
217 }
218
change_protection(struct vm_area_struct * vma,unsigned long start,unsigned long end,pgprot_t newprot,int dirty_accountable,int prot_numa)219 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
220 unsigned long end, pgprot_t newprot,
221 int dirty_accountable, int prot_numa)
222 {
223 struct mm_struct *mm = vma->vm_mm;
224 unsigned long pages;
225
226 mmu_notifier_invalidate_range_start(mm, start, end);
227 if (is_vm_hugetlb_page(vma))
228 pages = hugetlb_change_protection(vma, start, end, newprot);
229 else
230 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
231 mmu_notifier_invalidate_range_end(mm, start, end);
232
233 return pages;
234 }
235
236 int
mprotect_fixup(struct vm_area_struct * vma,struct vm_area_struct ** pprev,unsigned long start,unsigned long end,unsigned long newflags)237 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
238 unsigned long start, unsigned long end, unsigned long newflags)
239 {
240 struct mm_struct *mm = vma->vm_mm;
241 unsigned long oldflags = vma->vm_flags;
242 long nrpages = (end - start) >> PAGE_SHIFT;
243 unsigned long charged = 0;
244 pgoff_t pgoff;
245 int error;
246 int dirty_accountable = 0;
247
248 if (newflags == oldflags) {
249 *pprev = vma;
250 return 0;
251 }
252
253 /*
254 * If we make a private mapping writable we increase our commit;
255 * but (without finer accounting) cannot reduce our commit if we
256 * make it unwritable again. hugetlb mapping were accounted for
257 * even if read-only so there is no need to account for them here
258 */
259 if (newflags & VM_WRITE) {
260 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
261 VM_SHARED|VM_NORESERVE))) {
262 charged = nrpages;
263 if (security_vm_enough_memory_mm(mm, charged))
264 return -ENOMEM;
265 newflags |= VM_ACCOUNT;
266 }
267 }
268
269 /*
270 * First try to merge with previous and/or next vma.
271 */
272 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
273 *pprev = vma_merge(mm, *pprev, start, end, newflags,
274 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
275 vma_get_anon_name(vma));
276 if (*pprev) {
277 vma = *pprev;
278 goto success;
279 }
280
281 *pprev = vma;
282
283 if (start != vma->vm_start) {
284 error = split_vma(mm, vma, start, 1);
285 if (error)
286 goto fail;
287 }
288
289 if (end != vma->vm_end) {
290 error = split_vma(mm, vma, end, 0);
291 if (error)
292 goto fail;
293 }
294
295 success:
296 /*
297 * vm_flags and vm_page_prot are protected by the mmap_sem
298 * held in write mode.
299 */
300 vma->vm_flags = newflags;
301 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
302 vm_get_page_prot(newflags));
303
304 if (vma_wants_writenotify(vma)) {
305 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
306 dirty_accountable = 1;
307 }
308
309 change_protection(vma, start, end, vma->vm_page_prot,
310 dirty_accountable, 0);
311
312 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
313 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
314 perf_event_mmap(vma);
315 return 0;
316
317 fail:
318 vm_unacct_memory(charged);
319 return error;
320 }
321
SYSCALL_DEFINE3(mprotect,unsigned long,start,size_t,len,unsigned long,prot)322 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
323 unsigned long, prot)
324 {
325 unsigned long vm_flags, nstart, end, tmp, reqprot;
326 struct vm_area_struct *vma, *prev;
327 int error = -EINVAL;
328 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
329 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
330 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
331 return -EINVAL;
332
333 if (start & ~PAGE_MASK)
334 return -EINVAL;
335 if (!len)
336 return 0;
337 len = PAGE_ALIGN(len);
338 end = start + len;
339 if (end <= start)
340 return -ENOMEM;
341 if (!arch_validate_prot(prot))
342 return -EINVAL;
343
344 reqprot = prot;
345 /*
346 * Does the application expect PROT_READ to imply PROT_EXEC:
347 */
348 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
349 prot |= PROT_EXEC;
350
351 vm_flags = calc_vm_prot_bits(prot);
352
353 down_write(¤t->mm->mmap_sem);
354
355 vma = find_vma(current->mm, start);
356 error = -ENOMEM;
357 if (!vma)
358 goto out;
359 prev = vma->vm_prev;
360 if (unlikely(grows & PROT_GROWSDOWN)) {
361 if (vma->vm_start >= end)
362 goto out;
363 start = vma->vm_start;
364 error = -EINVAL;
365 if (!(vma->vm_flags & VM_GROWSDOWN))
366 goto out;
367 } else {
368 if (vma->vm_start > start)
369 goto out;
370 if (unlikely(grows & PROT_GROWSUP)) {
371 end = vma->vm_end;
372 error = -EINVAL;
373 if (!(vma->vm_flags & VM_GROWSUP))
374 goto out;
375 }
376 }
377 if (start > vma->vm_start)
378 prev = vma;
379
380 for (nstart = start ; ; ) {
381 unsigned long newflags;
382
383 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
384
385 newflags = vm_flags;
386 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
387
388 /* newflags >> 4 shift VM_MAY% in place of VM_% */
389 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
390 error = -EACCES;
391 goto out;
392 }
393
394 error = security_file_mprotect(vma, reqprot, prot);
395 if (error)
396 goto out;
397
398 tmp = vma->vm_end;
399 if (tmp > end)
400 tmp = end;
401 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
402 if (error)
403 goto out;
404 nstart = tmp;
405
406 if (nstart < prev->vm_end)
407 nstart = prev->vm_end;
408 if (nstart >= end)
409 goto out;
410
411 vma = prev->vm_next;
412 if (!vma || vma->vm_start != nstart) {
413 error = -ENOMEM;
414 goto out;
415 }
416 }
417 out:
418 up_write(¤t->mm->mmap_sem);
419 return error;
420 }
421