]>
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 | ||
36f88188 KS |
32 | #include "internal.h" |
33 | ||
1ad9f620 MG |
34 | /* |
35 | * For a prot_numa update we only hold mmap_sem for read so there is a | |
36 | * potential race with faulting where a pmd was temporarily none. This | |
37 | * function checks for a transhuge pmd under the appropriate lock. It | |
38 | * returns a pte if it was successfully locked or NULL if it raced with | |
39 | * a transhuge insertion. | |
40 | */ | |
41 | static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd, | |
42 | unsigned long addr, int prot_numa, spinlock_t **ptl) | |
43 | { | |
44 | pte_t *pte; | |
45 | spinlock_t *pmdl; | |
46 | ||
47 | /* !prot_numa is protected by mmap_sem held for write */ | |
48 | if (!prot_numa) | |
49 | return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); | |
50 | ||
51 | pmdl = pmd_lock(vma->vm_mm, pmd); | |
52 | if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) { | |
53 | spin_unlock(pmdl); | |
54 | return NULL; | |
55 | } | |
56 | ||
57 | pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); | |
58 | spin_unlock(pmdl); | |
59 | return pte; | |
60 | } | |
61 | ||
4b10e7d5 | 62 | static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
c1e6098b | 63 | unsigned long addr, unsigned long end, pgprot_t newprot, |
0f19c179 | 64 | int dirty_accountable, int prot_numa) |
1da177e4 | 65 | { |
4b10e7d5 | 66 | struct mm_struct *mm = vma->vm_mm; |
0697212a | 67 | pte_t *pte, oldpte; |
705e87c0 | 68 | spinlock_t *ptl; |
7da4d641 | 69 | unsigned long pages = 0; |
1da177e4 | 70 | |
1ad9f620 MG |
71 | pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl); |
72 | if (!pte) | |
73 | return 0; | |
74 | ||
064bbcf7 | 75 | flush_tlb_batched_pending(vma->vm_mm); |
6606c3e0 | 76 | arch_enter_lazy_mmu_mode(); |
1da177e4 | 77 | do { |
0697212a CL |
78 | oldpte = *pte; |
79 | if (pte_present(oldpte)) { | |
1da177e4 | 80 | pte_t ptent; |
b191f9b1 | 81 | bool preserve_write = prot_numa && pte_write(oldpte); |
1da177e4 | 82 | |
e944fd67 MG |
83 | /* |
84 | * Avoid trapping faults against the zero or KSM | |
85 | * pages. See similar comment in change_huge_pmd. | |
86 | */ | |
87 | if (prot_numa) { | |
88 | struct page *page; | |
89 | ||
90 | page = vm_normal_page(vma, addr, oldpte); | |
91 | if (!page || PageKsm(page)) | |
92 | continue; | |
10c1045f MG |
93 | |
94 | /* Avoid TLB flush if possible */ | |
95 | if (pte_protnone(oldpte)) | |
96 | continue; | |
e944fd67 MG |
97 | } |
98 | ||
8a0516ed MG |
99 | ptent = ptep_modify_prot_start(mm, addr, pte); |
100 | ptent = pte_modify(ptent, newprot); | |
b191f9b1 MG |
101 | if (preserve_write) |
102 | ptent = pte_mkwrite(ptent); | |
4b10e7d5 | 103 | |
8a0516ed MG |
104 | /* Avoid taking write faults for known dirty pages */ |
105 | if (dirty_accountable && pte_dirty(ptent) && | |
106 | (pte_soft_dirty(ptent) || | |
107 | !(vma->vm_flags & VM_SOFTDIRTY))) { | |
108 | ptent = pte_mkwrite(ptent); | |
4b10e7d5 | 109 | } |
8a0516ed MG |
110 | ptep_modify_prot_commit(mm, addr, pte, ptent); |
111 | pages++; | |
0661a336 | 112 | } else if (IS_ENABLED(CONFIG_MIGRATION)) { |
0697212a CL |
113 | swp_entry_t entry = pte_to_swp_entry(oldpte); |
114 | ||
115 | if (is_write_migration_entry(entry)) { | |
c3d16e16 | 116 | pte_t newpte; |
0697212a CL |
117 | /* |
118 | * A protection check is difficult so | |
119 | * just be safe and disable write | |
120 | */ | |
121 | make_migration_entry_read(&entry); | |
c3d16e16 CG |
122 | newpte = swp_entry_to_pte(entry); |
123 | if (pte_swp_soft_dirty(oldpte)) | |
124 | newpte = pte_swp_mksoft_dirty(newpte); | |
125 | set_pte_at(mm, addr, pte, newpte); | |
e920e14c MG |
126 | |
127 | pages++; | |
0697212a | 128 | } |
1da177e4 LT |
129 | } |
130 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
6606c3e0 | 131 | arch_leave_lazy_mmu_mode(); |
705e87c0 | 132 | pte_unmap_unlock(pte - 1, ptl); |
7da4d641 PZ |
133 | |
134 | return pages; | |
1da177e4 LT |
135 | } |
136 | ||
7d12efae AM |
137 | static inline unsigned long change_pmd_range(struct vm_area_struct *vma, |
138 | pud_t *pud, unsigned long addr, unsigned long end, | |
139 | pgprot_t newprot, int dirty_accountable, int prot_numa) | |
1da177e4 LT |
140 | { |
141 | pmd_t *pmd; | |
a5338093 | 142 | struct mm_struct *mm = vma->vm_mm; |
1da177e4 | 143 | unsigned long next; |
7da4d641 | 144 | unsigned long pages = 0; |
72403b4a | 145 | unsigned long nr_huge_updates = 0; |
a5338093 | 146 | unsigned long mni_start = 0; |
1da177e4 LT |
147 | |
148 | pmd = pmd_offset(pud, addr); | |
149 | do { | |
25cbbef1 MG |
150 | unsigned long this_pages; |
151 | ||
1da177e4 | 152 | next = pmd_addr_end(addr, end); |
88a9ab6e RR |
153 | if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd)) |
154 | continue; | |
a5338093 RR |
155 | |
156 | /* invoke the mmu notifier if the pmd is populated */ | |
157 | if (!mni_start) { | |
158 | mni_start = addr; | |
159 | mmu_notifier_invalidate_range_start(mm, mni_start, end); | |
160 | } | |
161 | ||
cd7548ab JW |
162 | if (pmd_trans_huge(*pmd)) { |
163 | if (next - addr != HPAGE_PMD_SIZE) | |
e180377f | 164 | split_huge_page_pmd(vma, addr, pmd); |
f123d74a MG |
165 | else { |
166 | int nr_ptes = change_huge_pmd(vma, pmd, addr, | |
e944fd67 | 167 | newprot, prot_numa); |
f123d74a MG |
168 | |
169 | if (nr_ptes) { | |
72403b4a MG |
170 | if (nr_ptes == HPAGE_PMD_NR) { |
171 | pages += HPAGE_PMD_NR; | |
172 | nr_huge_updates++; | |
173 | } | |
1ad9f620 MG |
174 | |
175 | /* huge pmd was handled */ | |
f123d74a MG |
176 | continue; |
177 | } | |
7da4d641 | 178 | } |
88a9ab6e | 179 | /* fall through, the trans huge pmd just split */ |
cd7548ab | 180 | } |
25cbbef1 | 181 | this_pages = change_pte_range(vma, pmd, addr, next, newprot, |
0f19c179 | 182 | dirty_accountable, prot_numa); |
25cbbef1 | 183 | pages += this_pages; |
1da177e4 | 184 | } while (pmd++, addr = next, addr != end); |
7da4d641 | 185 | |
a5338093 RR |
186 | if (mni_start) |
187 | mmu_notifier_invalidate_range_end(mm, mni_start, end); | |
188 | ||
72403b4a MG |
189 | if (nr_huge_updates) |
190 | count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); | |
7da4d641 | 191 | return pages; |
1da177e4 LT |
192 | } |
193 | ||
7d12efae AM |
194 | static inline unsigned long change_pud_range(struct vm_area_struct *vma, |
195 | pgd_t *pgd, unsigned long addr, unsigned long end, | |
196 | pgprot_t newprot, int dirty_accountable, int prot_numa) | |
1da177e4 LT |
197 | { |
198 | pud_t *pud; | |
199 | unsigned long next; | |
7da4d641 | 200 | unsigned long pages = 0; |
1da177e4 LT |
201 | |
202 | pud = pud_offset(pgd, addr); | |
203 | do { | |
204 | next = pud_addr_end(addr, end); | |
205 | if (pud_none_or_clear_bad(pud)) | |
206 | continue; | |
7da4d641 | 207 | pages += change_pmd_range(vma, pud, addr, next, newprot, |
4b10e7d5 | 208 | dirty_accountable, prot_numa); |
1da177e4 | 209 | } while (pud++, addr = next, addr != end); |
7da4d641 PZ |
210 | |
211 | return pages; | |
1da177e4 LT |
212 | } |
213 | ||
7da4d641 | 214 | static unsigned long change_protection_range(struct vm_area_struct *vma, |
c1e6098b | 215 | unsigned long addr, unsigned long end, pgprot_t newprot, |
4b10e7d5 | 216 | int dirty_accountable, int prot_numa) |
1da177e4 LT |
217 | { |
218 | struct mm_struct *mm = vma->vm_mm; | |
219 | pgd_t *pgd; | |
220 | unsigned long next; | |
221 | unsigned long start = addr; | |
7da4d641 | 222 | unsigned long pages = 0; |
1da177e4 LT |
223 | |
224 | BUG_ON(addr >= end); | |
225 | pgd = pgd_offset(mm, addr); | |
226 | flush_cache_range(vma, addr, end); | |
20841405 | 227 | set_tlb_flush_pending(mm); |
1da177e4 LT |
228 | do { |
229 | next = pgd_addr_end(addr, end); | |
230 | if (pgd_none_or_clear_bad(pgd)) | |
231 | continue; | |
7da4d641 | 232 | pages += change_pud_range(vma, pgd, addr, next, newprot, |
4b10e7d5 | 233 | dirty_accountable, prot_numa); |
1da177e4 | 234 | } while (pgd++, addr = next, addr != end); |
7da4d641 | 235 | |
1233d588 IM |
236 | /* Only flush the TLB if we actually modified any entries: */ |
237 | if (pages) | |
238 | flush_tlb_range(vma, start, end); | |
20841405 | 239 | clear_tlb_flush_pending(mm); |
7da4d641 PZ |
240 | |
241 | return pages; | |
242 | } | |
243 | ||
244 | unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, | |
245 | unsigned long end, pgprot_t newprot, | |
4b10e7d5 | 246 | int dirty_accountable, int prot_numa) |
7da4d641 | 247 | { |
7da4d641 PZ |
248 | unsigned long pages; |
249 | ||
7da4d641 PZ |
250 | if (is_vm_hugetlb_page(vma)) |
251 | pages = hugetlb_change_protection(vma, start, end, newprot); | |
252 | else | |
4b10e7d5 | 253 | pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa); |
7da4d641 PZ |
254 | |
255 | return pages; | |
1da177e4 LT |
256 | } |
257 | ||
b6a2fea3 | 258 | int |
1da177e4 LT |
259 | mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, |
260 | unsigned long start, unsigned long end, unsigned long newflags) | |
261 | { | |
262 | struct mm_struct *mm = vma->vm_mm; | |
263 | unsigned long oldflags = vma->vm_flags; | |
264 | long nrpages = (end - start) >> PAGE_SHIFT; | |
265 | unsigned long charged = 0; | |
1da177e4 LT |
266 | pgoff_t pgoff; |
267 | int error; | |
c1e6098b | 268 | int dirty_accountable = 0; |
1da177e4 LT |
269 | |
270 | if (newflags == oldflags) { | |
271 | *pprev = vma; | |
272 | return 0; | |
273 | } | |
274 | ||
275 | /* | |
276 | * If we make a private mapping writable we increase our commit; | |
277 | * but (without finer accounting) cannot reduce our commit if we | |
5a6fe125 MG |
278 | * make it unwritable again. hugetlb mapping were accounted for |
279 | * even if read-only so there is no need to account for them here | |
1da177e4 LT |
280 | */ |
281 | if (newflags & VM_WRITE) { | |
5a6fe125 | 282 | if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| |
cdfd4325 | 283 | VM_SHARED|VM_NORESERVE))) { |
1da177e4 | 284 | charged = nrpages; |
191c5424 | 285 | if (security_vm_enough_memory_mm(mm, charged)) |
1da177e4 LT |
286 | return -ENOMEM; |
287 | newflags |= VM_ACCOUNT; | |
288 | } | |
289 | } | |
290 | ||
1da177e4 LT |
291 | /* |
292 | * First try to merge with previous and/or next vma. | |
293 | */ | |
294 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
295 | *pprev = vma_merge(mm, *pprev, start, end, newflags, | |
19a809af AA |
296 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), |
297 | vma->vm_userfaultfd_ctx); | |
1da177e4 LT |
298 | if (*pprev) { |
299 | vma = *pprev; | |
300 | goto success; | |
301 | } | |
302 | ||
303 | *pprev = vma; | |
304 | ||
305 | if (start != vma->vm_start) { | |
306 | error = split_vma(mm, vma, start, 1); | |
307 | if (error) | |
308 | goto fail; | |
309 | } | |
310 | ||
311 | if (end != vma->vm_end) { | |
312 | error = split_vma(mm, vma, end, 0); | |
313 | if (error) | |
314 | goto fail; | |
315 | } | |
316 | ||
317 | success: | |
318 | /* | |
319 | * vm_flags and vm_page_prot are protected by the mmap_sem | |
320 | * held in write mode. | |
321 | */ | |
322 | vma->vm_flags = newflags; | |
64e45507 PF |
323 | dirty_accountable = vma_wants_writenotify(vma); |
324 | vma_set_page_prot(vma); | |
d08b3851 | 325 | |
7d12efae AM |
326 | change_protection(vma, start, end, vma->vm_page_prot, |
327 | dirty_accountable, 0); | |
7da4d641 | 328 | |
36f88188 KS |
329 | /* |
330 | * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major | |
331 | * fault on access. | |
332 | */ | |
333 | if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && | |
334 | (newflags & VM_WRITE)) { | |
335 | populate_vma_page_range(vma, start, end, NULL); | |
336 | } | |
337 | ||
ab50b8ed HD |
338 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
339 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); | |
63bfd738 | 340 | perf_event_mmap(vma); |
1da177e4 LT |
341 | return 0; |
342 | ||
343 | fail: | |
344 | vm_unacct_memory(charged); | |
345 | return error; | |
346 | } | |
347 | ||
6a6160a7 HC |
348 | SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, |
349 | unsigned long, prot) | |
1da177e4 LT |
350 | { |
351 | unsigned long vm_flags, nstart, end, tmp, reqprot; | |
352 | struct vm_area_struct *vma, *prev; | |
353 | int error = -EINVAL; | |
354 | const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); | |
355 | prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); | |
356 | if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ | |
357 | return -EINVAL; | |
358 | ||
359 | if (start & ~PAGE_MASK) | |
360 | return -EINVAL; | |
361 | if (!len) | |
362 | return 0; | |
363 | len = PAGE_ALIGN(len); | |
364 | end = start + len; | |
365 | if (end <= start) | |
366 | return -ENOMEM; | |
b845f313 | 367 | if (!arch_validate_prot(prot)) |
1da177e4 LT |
368 | return -EINVAL; |
369 | ||
370 | reqprot = prot; | |
371 | /* | |
372 | * Does the application expect PROT_READ to imply PROT_EXEC: | |
373 | */ | |
b344e05c | 374 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
1da177e4 LT |
375 | prot |= PROT_EXEC; |
376 | ||
377 | vm_flags = calc_vm_prot_bits(prot); | |
378 | ||
379 | down_write(¤t->mm->mmap_sem); | |
380 | ||
097d5910 | 381 | vma = find_vma(current->mm, start); |
1da177e4 LT |
382 | error = -ENOMEM; |
383 | if (!vma) | |
384 | goto out; | |
097d5910 | 385 | prev = vma->vm_prev; |
1da177e4 LT |
386 | if (unlikely(grows & PROT_GROWSDOWN)) { |
387 | if (vma->vm_start >= end) | |
388 | goto out; | |
389 | start = vma->vm_start; | |
390 | error = -EINVAL; | |
391 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
392 | goto out; | |
7d12efae | 393 | } else { |
1da177e4 LT |
394 | if (vma->vm_start > start) |
395 | goto out; | |
396 | if (unlikely(grows & PROT_GROWSUP)) { | |
397 | end = vma->vm_end; | |
398 | error = -EINVAL; | |
399 | if (!(vma->vm_flags & VM_GROWSUP)) | |
400 | goto out; | |
401 | } | |
402 | } | |
403 | if (start > vma->vm_start) | |
404 | prev = vma; | |
405 | ||
406 | for (nstart = start ; ; ) { | |
407 | unsigned long newflags; | |
408 | ||
7d12efae | 409 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
1da177e4 | 410 | |
7d12efae AM |
411 | newflags = vm_flags; |
412 | newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); | |
1da177e4 | 413 | |
7e2cff42 PBG |
414 | /* newflags >> 4 shift VM_MAY% in place of VM_% */ |
415 | if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { | |
1da177e4 LT |
416 | error = -EACCES; |
417 | goto out; | |
418 | } | |
419 | ||
420 | error = security_file_mprotect(vma, reqprot, prot); | |
421 | if (error) | |
422 | goto out; | |
423 | ||
424 | tmp = vma->vm_end; | |
425 | if (tmp > end) | |
426 | tmp = end; | |
427 | error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); | |
428 | if (error) | |
429 | goto out; | |
430 | nstart = tmp; | |
431 | ||
432 | if (nstart < prev->vm_end) | |
433 | nstart = prev->vm_end; | |
434 | if (nstart >= end) | |
435 | goto out; | |
436 | ||
437 | vma = prev->vm_next; | |
438 | if (!vma || vma->vm_start != nstart) { | |
439 | error = -ENOMEM; | |
440 | goto out; | |
441 | } | |
442 | } | |
443 | out: | |
444 | up_write(¤t->mm->mmap_sem); | |
445 | return error; | |
446 | } |