Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * mm/mprotect.c | |
3 | * | |
4 | * (C) Copyright 1994 Linus Torvalds | |
5 | * (C) Copyright 2002 Christoph Hellwig | |
6 | * | |
046c6884 | 7 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
1da177e4 LT |
8 | * (C) Copyright 2002 Red Hat Inc, All Rights Reserved |
9 | */ | |
10 | ||
11 | #include <linux/mm.h> | |
12 | #include <linux/hugetlb.h> | |
1da177e4 LT |
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> | |
0697212a CL |
21 | #include <linux/swap.h> |
22 | #include <linux/swapops.h> | |
cddb8a5c | 23 | #include <linux/mmu_notifier.h> |
64cdd548 | 24 | #include <linux/migrate.h> |
cdd6c482 | 25 | #include <linux/perf_event.h> |
64a9a34e | 26 | #include <linux/ksm.h> |
1da177e4 LT |
27 | #include <asm/uaccess.h> |
28 | #include <asm/pgtable.h> | |
29 | #include <asm/cacheflush.h> | |
30 | #include <asm/tlbflush.h> | |
31 | ||
1c12c4cf VP |
32 | #ifndef pgprot_modify |
33 | static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) | |
34 | { | |
35 | return newprot; | |
36 | } | |
37 | #endif | |
38 | ||
1ad9f620 MG |
39 | /* |
40 | * For a prot_numa update we only hold mmap_sem for read so there is a | |
41 | * potential race with faulting where a pmd was temporarily none. This | |
42 | * function checks for a transhuge pmd under the appropriate lock. It | |
43 | * returns a pte if it was successfully locked or NULL if it raced with | |
44 | * a transhuge insertion. | |
45 | */ | |
46 | static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd, | |
47 | unsigned long addr, int prot_numa, spinlock_t **ptl) | |
48 | { | |
49 | pte_t *pte; | |
50 | spinlock_t *pmdl; | |
51 | ||
52 | /* !prot_numa is protected by mmap_sem held for write */ | |
53 | if (!prot_numa) | |
54 | return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); | |
55 | ||
56 | pmdl = pmd_lock(vma->vm_mm, pmd); | |
57 | if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) { | |
58 | spin_unlock(pmdl); | |
59 | return NULL; | |
60 | } | |
61 | ||
62 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); | |
63 | spin_unlock(pmdl); | |
64 | return pte; | |
65 | } | |
66 | ||
4b10e7d5 | 67 | static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
c1e6098b | 68 | unsigned long addr, unsigned long end, pgprot_t newprot, |
0f19c179 | 69 | int dirty_accountable, int prot_numa) |
1da177e4 | 70 | { |
4b10e7d5 | 71 | struct mm_struct *mm = vma->vm_mm; |
0697212a | 72 | pte_t *pte, oldpte; |
705e87c0 | 73 | spinlock_t *ptl; |
7da4d641 | 74 | unsigned long pages = 0; |
1da177e4 | 75 | |
1ad9f620 MG |
76 | pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl); |
77 | if (!pte) | |
78 | return 0; | |
79 | ||
6606c3e0 | 80 | arch_enter_lazy_mmu_mode(); |
1da177e4 | 81 | do { |
0697212a CL |
82 | oldpte = *pte; |
83 | if (pte_present(oldpte)) { | |
1da177e4 | 84 | pte_t ptent; |
4b10e7d5 | 85 | bool updated = false; |
1da177e4 | 86 | |
4b10e7d5 | 87 | if (!prot_numa) { |
0c5f83c2 | 88 | ptent = ptep_modify_prot_start(mm, addr, pte); |
1667918b MG |
89 | if (pte_numa(ptent)) |
90 | ptent = pte_mknonnuma(ptent); | |
4b10e7d5 | 91 | ptent = pte_modify(ptent, newprot); |
9d85d586 AK |
92 | /* |
93 | * Avoid taking write faults for pages we | |
94 | * know to be dirty. | |
95 | */ | |
96 | if (dirty_accountable && pte_dirty(ptent)) | |
97 | ptent = pte_mkwrite(ptent); | |
98 | ptep_modify_prot_commit(mm, addr, pte, ptent); | |
4b10e7d5 MG |
99 | updated = true; |
100 | } else { | |
101 | struct page *page; | |
102 | ||
103 | page = vm_normal_page(vma, addr, oldpte); | |
64a9a34e | 104 | if (page && !PageKsm(page)) { |
1bc115d8 | 105 | if (!pte_numa(oldpte)) { |
56eecdb9 | 106 | ptep_set_numa(mm, addr, pte); |
4b10e7d5 MG |
107 | updated = true; |
108 | } | |
109 | } | |
110 | } | |
4b10e7d5 MG |
111 | if (updated) |
112 | pages++; | |
ce1744f4 | 113 | } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) { |
0697212a CL |
114 | swp_entry_t entry = pte_to_swp_entry(oldpte); |
115 | ||
116 | if (is_write_migration_entry(entry)) { | |
c3d16e16 | 117 | pte_t newpte; |
0697212a CL |
118 | /* |
119 | * A protection check is difficult so | |
120 | * just be safe and disable write | |
121 | */ | |
122 | make_migration_entry_read(&entry); | |
c3d16e16 CG |
123 | newpte = swp_entry_to_pte(entry); |
124 | if (pte_swp_soft_dirty(oldpte)) | |
125 | newpte = pte_swp_mksoft_dirty(newpte); | |
126 | set_pte_at(mm, addr, pte, newpte); | |
e920e14c MG |
127 | |
128 | pages++; | |
0697212a | 129 | } |
1da177e4 LT |
130 | } |
131 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
6606c3e0 | 132 | arch_leave_lazy_mmu_mode(); |
705e87c0 | 133 | pte_unmap_unlock(pte - 1, ptl); |
7da4d641 PZ |
134 | |
135 | return pages; | |
1da177e4 LT |
136 | } |
137 | ||
7d12efae AM |
138 | static inline unsigned long change_pmd_range(struct vm_area_struct *vma, |
139 | pud_t *pud, unsigned long addr, unsigned long end, | |
140 | pgprot_t newprot, int dirty_accountable, int prot_numa) | |
1da177e4 LT |
141 | { |
142 | pmd_t *pmd; | |
143 | unsigned long next; | |
7da4d641 | 144 | unsigned long pages = 0; |
72403b4a | 145 | unsigned long nr_huge_updates = 0; |
1da177e4 LT |
146 | |
147 | pmd = pmd_offset(pud, addr); | |
148 | do { | |
25cbbef1 MG |
149 | unsigned long this_pages; |
150 | ||
1da177e4 | 151 | next = pmd_addr_end(addr, end); |
88a9ab6e RR |
152 | if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd)) |
153 | continue; | |
cd7548ab JW |
154 | if (pmd_trans_huge(*pmd)) { |
155 | if (next - addr != HPAGE_PMD_SIZE) | |
e180377f | 156 | split_huge_page_pmd(vma, addr, pmd); |
f123d74a MG |
157 | else { |
158 | int nr_ptes = change_huge_pmd(vma, pmd, addr, | |
159 | newprot, prot_numa); | |
160 | ||
161 | if (nr_ptes) { | |
72403b4a MG |
162 | if (nr_ptes == HPAGE_PMD_NR) { |
163 | pages += HPAGE_PMD_NR; | |
164 | nr_huge_updates++; | |
165 | } | |
1ad9f620 MG |
166 | |
167 | /* huge pmd was handled */ | |
f123d74a MG |
168 | continue; |
169 | } | |
7da4d641 | 170 | } |
88a9ab6e | 171 | /* fall through, the trans huge pmd just split */ |
cd7548ab | 172 | } |
25cbbef1 | 173 | this_pages = change_pte_range(vma, pmd, addr, next, newprot, |
0f19c179 | 174 | dirty_accountable, prot_numa); |
25cbbef1 | 175 | pages += this_pages; |
1da177e4 | 176 | } while (pmd++, addr = next, addr != end); |
7da4d641 | 177 | |
72403b4a MG |
178 | if (nr_huge_updates) |
179 | count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); | |
7da4d641 | 180 | return pages; |
1da177e4 LT |
181 | } |
182 | ||
7d12efae AM |
183 | static inline unsigned long change_pud_range(struct vm_area_struct *vma, |
184 | pgd_t *pgd, unsigned long addr, unsigned long end, | |
185 | pgprot_t newprot, int dirty_accountable, int prot_numa) | |
1da177e4 LT |
186 | { |
187 | pud_t *pud; | |
188 | unsigned long next; | |
7da4d641 | 189 | unsigned long pages = 0; |
1da177e4 LT |
190 | |
191 | pud = pud_offset(pgd, addr); | |
192 | do { | |
193 | next = pud_addr_end(addr, end); | |
194 | if (pud_none_or_clear_bad(pud)) | |
195 | continue; | |
7da4d641 | 196 | pages += change_pmd_range(vma, pud, addr, next, newprot, |
4b10e7d5 | 197 | dirty_accountable, prot_numa); |
1da177e4 | 198 | } while (pud++, addr = next, addr != end); |
7da4d641 PZ |
199 | |
200 | return pages; | |
1da177e4 LT |
201 | } |
202 | ||
7da4d641 | 203 | static unsigned long change_protection_range(struct vm_area_struct *vma, |
c1e6098b | 204 | unsigned long addr, unsigned long end, pgprot_t newprot, |
4b10e7d5 | 205 | int dirty_accountable, int prot_numa) |
1da177e4 LT |
206 | { |
207 | struct mm_struct *mm = vma->vm_mm; | |
208 | pgd_t *pgd; | |
209 | unsigned long next; | |
210 | unsigned long start = addr; | |
7da4d641 | 211 | unsigned long pages = 0; |
1da177e4 LT |
212 | |
213 | BUG_ON(addr >= end); | |
214 | pgd = pgd_offset(mm, addr); | |
215 | flush_cache_range(vma, addr, end); | |
20841405 | 216 | set_tlb_flush_pending(mm); |
1da177e4 LT |
217 | do { |
218 | next = pgd_addr_end(addr, end); | |
219 | if (pgd_none_or_clear_bad(pgd)) | |
220 | continue; | |
7da4d641 | 221 | pages += change_pud_range(vma, pgd, addr, next, newprot, |
4b10e7d5 | 222 | dirty_accountable, prot_numa); |
1da177e4 | 223 | } while (pgd++, addr = next, addr != end); |
7da4d641 | 224 | |
1233d588 IM |
225 | /* Only flush the TLB if we actually modified any entries: */ |
226 | if (pages) | |
227 | flush_tlb_range(vma, start, end); | |
20841405 | 228 | clear_tlb_flush_pending(mm); |
7da4d641 PZ |
229 | |
230 | return pages; | |
231 | } | |
232 | ||
233 | unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, | |
234 | unsigned long end, pgprot_t newprot, | |
4b10e7d5 | 235 | int dirty_accountable, int prot_numa) |
7da4d641 PZ |
236 | { |
237 | struct mm_struct *mm = vma->vm_mm; | |
238 | unsigned long pages; | |
239 | ||
240 | mmu_notifier_invalidate_range_start(mm, start, end); | |
241 | if (is_vm_hugetlb_page(vma)) | |
242 | pages = hugetlb_change_protection(vma, start, end, newprot); | |
243 | else | |
4b10e7d5 | 244 | pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa); |
7da4d641 PZ |
245 | mmu_notifier_invalidate_range_end(mm, start, end); |
246 | ||
247 | return pages; | |
1da177e4 LT |
248 | } |
249 | ||
b6a2fea3 | 250 | int |
1da177e4 LT |
251 | mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, |
252 | unsigned long start, unsigned long end, unsigned long newflags) | |
253 | { | |
254 | struct mm_struct *mm = vma->vm_mm; | |
255 | unsigned long oldflags = vma->vm_flags; | |
256 | long nrpages = (end - start) >> PAGE_SHIFT; | |
257 | unsigned long charged = 0; | |
1da177e4 LT |
258 | pgoff_t pgoff; |
259 | int error; | |
c1e6098b | 260 | int dirty_accountable = 0; |
1da177e4 LT |
261 | |
262 | if (newflags == oldflags) { | |
263 | *pprev = vma; | |
264 | return 0; | |
265 | } | |
266 | ||
267 | /* | |
268 | * If we make a private mapping writable we increase our commit; | |
269 | * but (without finer accounting) cannot reduce our commit if we | |
5a6fe125 MG |
270 | * make it unwritable again. hugetlb mapping were accounted for |
271 | * even if read-only so there is no need to account for them here | |
1da177e4 LT |
272 | */ |
273 | if (newflags & VM_WRITE) { | |
5a6fe125 | 274 | if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| |
cdfd4325 | 275 | VM_SHARED|VM_NORESERVE))) { |
1da177e4 | 276 | charged = nrpages; |
191c5424 | 277 | if (security_vm_enough_memory_mm(mm, charged)) |
1da177e4 LT |
278 | return -ENOMEM; |
279 | newflags |= VM_ACCOUNT; | |
280 | } | |
281 | } | |
282 | ||
1da177e4 LT |
283 | /* |
284 | * First try to merge with previous and/or next vma. | |
285 | */ | |
286 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
287 | *pprev = vma_merge(mm, *pprev, start, end, newflags, | |
288 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); | |
289 | if (*pprev) { | |
290 | vma = *pprev; | |
291 | goto success; | |
292 | } | |
293 | ||
294 | *pprev = vma; | |
295 | ||
296 | if (start != vma->vm_start) { | |
297 | error = split_vma(mm, vma, start, 1); | |
298 | if (error) | |
299 | goto fail; | |
300 | } | |
301 | ||
302 | if (end != vma->vm_end) { | |
303 | error = split_vma(mm, vma, end, 0); | |
304 | if (error) | |
305 | goto fail; | |
306 | } | |
307 | ||
308 | success: | |
309 | /* | |
310 | * vm_flags and vm_page_prot are protected by the mmap_sem | |
311 | * held in write mode. | |
312 | */ | |
313 | vma->vm_flags = newflags; | |
1c12c4cf VP |
314 | vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, |
315 | vm_get_page_prot(newflags)); | |
316 | ||
c1e6098b | 317 | if (vma_wants_writenotify(vma)) { |
1ddd439e | 318 | vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); |
c1e6098b PZ |
319 | dirty_accountable = 1; |
320 | } | |
d08b3851 | 321 | |
7d12efae AM |
322 | change_protection(vma, start, end, vma->vm_page_prot, |
323 | dirty_accountable, 0); | |
7da4d641 | 324 | |
ab50b8ed HD |
325 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
326 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); | |
63bfd738 | 327 | perf_event_mmap(vma); |
1da177e4 LT |
328 | return 0; |
329 | ||
330 | fail: | |
331 | vm_unacct_memory(charged); | |
332 | return error; | |
333 | } | |
334 | ||
6a6160a7 HC |
335 | SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, |
336 | unsigned long, prot) | |
1da177e4 LT |
337 | { |
338 | unsigned long vm_flags, nstart, end, tmp, reqprot; | |
339 | struct vm_area_struct *vma, *prev; | |
340 | int error = -EINVAL; | |
341 | const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); | |
342 | prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); | |
343 | if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ | |
344 | return -EINVAL; | |
345 | ||
346 | if (start & ~PAGE_MASK) | |
347 | return -EINVAL; | |
348 | if (!len) | |
349 | return 0; | |
350 | len = PAGE_ALIGN(len); | |
351 | end = start + len; | |
352 | if (end <= start) | |
353 | return -ENOMEM; | |
b845f313 | 354 | if (!arch_validate_prot(prot)) |
1da177e4 LT |
355 | return -EINVAL; |
356 | ||
357 | reqprot = prot; | |
358 | /* | |
359 | * Does the application expect PROT_READ to imply PROT_EXEC: | |
360 | */ | |
b344e05c | 361 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
1da177e4 LT |
362 | prot |= PROT_EXEC; |
363 | ||
364 | vm_flags = calc_vm_prot_bits(prot); | |
365 | ||
366 | down_write(¤t->mm->mmap_sem); | |
367 | ||
097d5910 | 368 | vma = find_vma(current->mm, start); |
1da177e4 LT |
369 | error = -ENOMEM; |
370 | if (!vma) | |
371 | goto out; | |
097d5910 | 372 | prev = vma->vm_prev; |
1da177e4 LT |
373 | if (unlikely(grows & PROT_GROWSDOWN)) { |
374 | if (vma->vm_start >= end) | |
375 | goto out; | |
376 | start = vma->vm_start; | |
377 | error = -EINVAL; | |
378 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
379 | goto out; | |
7d12efae | 380 | } else { |
1da177e4 LT |
381 | if (vma->vm_start > start) |
382 | goto out; | |
383 | if (unlikely(grows & PROT_GROWSUP)) { | |
384 | end = vma->vm_end; | |
385 | error = -EINVAL; | |
386 | if (!(vma->vm_flags & VM_GROWSUP)) | |
387 | goto out; | |
388 | } | |
389 | } | |
390 | if (start > vma->vm_start) | |
391 | prev = vma; | |
392 | ||
393 | for (nstart = start ; ; ) { | |
394 | unsigned long newflags; | |
395 | ||
7d12efae | 396 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
1da177e4 | 397 | |
7d12efae AM |
398 | newflags = vm_flags; |
399 | newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); | |
1da177e4 | 400 | |
7e2cff42 PBG |
401 | /* newflags >> 4 shift VM_MAY% in place of VM_% */ |
402 | if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { | |
1da177e4 LT |
403 | error = -EACCES; |
404 | goto out; | |
405 | } | |
406 | ||
407 | error = security_file_mprotect(vma, reqprot, prot); | |
408 | if (error) | |
409 | goto out; | |
410 | ||
411 | tmp = vma->vm_end; | |
412 | if (tmp > end) | |
413 | tmp = end; | |
414 | error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); | |
415 | if (error) | |
416 | goto out; | |
417 | nstart = tmp; | |
418 | ||
419 | if (nstart < prev->vm_end) | |
420 | nstart = prev->vm_end; | |
421 | if (nstart >= end) | |
422 | goto out; | |
423 | ||
424 | vma = prev->vm_next; | |
425 | if (!vma || vma->vm_start != nstart) { | |
426 | error = -ENOMEM; | |
427 | goto out; | |
428 | } | |
429 | } | |
430 | out: | |
431 | up_write(¤t->mm->mmap_sem); | |
432 | return error; | |
433 | } |