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CommitLineData
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>
62b5f7d0 27#include <linux/pkeys.h>
1da177e4
LT
28#include <asm/uaccess.h>
29#include <asm/pgtable.h>
30#include <asm/cacheflush.h>
31#include <asm/tlbflush.h>
32
36f88188
KS
33#include "internal.h"
34
1ad9f620
MG
35/*
36 * For a prot_numa update we only hold mmap_sem for read so there is a
37 * potential race with faulting where a pmd was temporarily none. This
38 * function checks for a transhuge pmd under the appropriate lock. It
39 * returns a pte if it was successfully locked or NULL if it raced with
40 * a transhuge insertion.
41 */
42static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
43 unsigned long addr, int prot_numa, spinlock_t **ptl)
44{
45 pte_t *pte;
46 spinlock_t *pmdl;
47
48 /* !prot_numa is protected by mmap_sem held for write */
49 if (!prot_numa)
50 return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
51
52 pmdl = pmd_lock(vma->vm_mm, pmd);
53 if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
54 spin_unlock(pmdl);
55 return NULL;
56 }
57
58 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
59 spin_unlock(pmdl);
60 return pte;
61}
62
4b10e7d5 63static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
c1e6098b 64 unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179 65 int dirty_accountable, int prot_numa)
1da177e4 66{
4b10e7d5 67 struct mm_struct *mm = vma->vm_mm;
0697212a 68 pte_t *pte, oldpte;
705e87c0 69 spinlock_t *ptl;
7da4d641 70 unsigned long pages = 0;
1da177e4 71
1ad9f620
MG
72 pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
73 if (!pte)
74 return 0;
75
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
137static 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);
5c7fb56e
DW
153 if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
154 && pmd_none_or_clear_bad(pmd))
88a9ab6e 155 continue;
a5338093
RR
156
157 /* invoke the mmu notifier if the pmd is populated */
158 if (!mni_start) {
159 mni_start = addr;
160 mmu_notifier_invalidate_range_start(mm, mni_start, end);
161 }
162
5c7fb56e 163 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
6b9116a6 164 if (next - addr != HPAGE_PMD_SIZE) {
78ddc534 165 split_huge_pmd(vma, pmd, addr);
337d9abf 166 if (pmd_trans_unstable(pmd))
6b9116a6
KS
167 continue;
168 } else {
f123d74a 169 int nr_ptes = change_huge_pmd(vma, pmd, addr,
e944fd67 170 newprot, prot_numa);
f123d74a
MG
171
172 if (nr_ptes) {
72403b4a
MG
173 if (nr_ptes == HPAGE_PMD_NR) {
174 pages += HPAGE_PMD_NR;
175 nr_huge_updates++;
176 }
1ad9f620
MG
177
178 /* huge pmd was handled */
f123d74a
MG
179 continue;
180 }
7da4d641 181 }
88a9ab6e 182 /* fall through, the trans huge pmd just split */
cd7548ab 183 }
25cbbef1 184 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179 185 dirty_accountable, prot_numa);
25cbbef1 186 pages += this_pages;
1da177e4 187 } while (pmd++, addr = next, addr != end);
7da4d641 188
a5338093
RR
189 if (mni_start)
190 mmu_notifier_invalidate_range_end(mm, mni_start, end);
191
72403b4a
MG
192 if (nr_huge_updates)
193 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641 194 return pages;
1da177e4
LT
195}
196
7d12efae
AM
197static inline unsigned long change_pud_range(struct vm_area_struct *vma,
198 pgd_t *pgd, unsigned long addr, unsigned long end,
199 pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4
LT
200{
201 pud_t *pud;
202 unsigned long next;
7da4d641 203 unsigned long pages = 0;
1da177e4
LT
204
205 pud = pud_offset(pgd, addr);
206 do {
207 next = pud_addr_end(addr, end);
208 if (pud_none_or_clear_bad(pud))
209 continue;
7da4d641 210 pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5 211 dirty_accountable, prot_numa);
1da177e4 212 } while (pud++, addr = next, addr != end);
7da4d641
PZ
213
214 return pages;
1da177e4
LT
215}
216
7da4d641 217static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b 218 unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5 219 int dirty_accountable, int prot_numa)
1da177e4
LT
220{
221 struct mm_struct *mm = vma->vm_mm;
222 pgd_t *pgd;
223 unsigned long next;
224 unsigned long start = addr;
7da4d641 225 unsigned long pages = 0;
1da177e4
LT
226
227 BUG_ON(addr >= end);
228 pgd = pgd_offset(mm, addr);
229 flush_cache_range(vma, addr, end);
20841405 230 set_tlb_flush_pending(mm);
1da177e4
LT
231 do {
232 next = pgd_addr_end(addr, end);
233 if (pgd_none_or_clear_bad(pgd))
234 continue;
7da4d641 235 pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5 236 dirty_accountable, prot_numa);
1da177e4 237 } while (pgd++, addr = next, addr != end);
7da4d641 238
1233d588
IM
239 /* Only flush the TLB if we actually modified any entries: */
240 if (pages)
241 flush_tlb_range(vma, start, end);
20841405 242 clear_tlb_flush_pending(mm);
7da4d641
PZ
243
244 return pages;
245}
246
247unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
248 unsigned long end, pgprot_t newprot,
4b10e7d5 249 int dirty_accountable, int prot_numa)
7da4d641 250{
7da4d641
PZ
251 unsigned long pages;
252
7da4d641
PZ
253 if (is_vm_hugetlb_page(vma))
254 pages = hugetlb_change_protection(vma, start, end, newprot);
255 else
4b10e7d5 256 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641
PZ
257
258 return pages;
1da177e4
LT
259}
260
b6a2fea3 261int
1da177e4
LT
262mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
263 unsigned long start, unsigned long end, unsigned long newflags)
264{
265 struct mm_struct *mm = vma->vm_mm;
266 unsigned long oldflags = vma->vm_flags;
267 long nrpages = (end - start) >> PAGE_SHIFT;
268 unsigned long charged = 0;
1da177e4
LT
269 pgoff_t pgoff;
270 int error;
c1e6098b 271 int dirty_accountable = 0;
1da177e4
LT
272
273 if (newflags == oldflags) {
274 *pprev = vma;
275 return 0;
276 }
277
278 /*
279 * If we make a private mapping writable we increase our commit;
280 * but (without finer accounting) cannot reduce our commit if we
5a6fe125
MG
281 * make it unwritable again. hugetlb mapping were accounted for
282 * even if read-only so there is no need to account for them here
1da177e4
LT
283 */
284 if (newflags & VM_WRITE) {
84638335
KK
285 /* Check space limits when area turns into data. */
286 if (!may_expand_vm(mm, newflags, nrpages) &&
287 may_expand_vm(mm, oldflags, nrpages))
288 return -ENOMEM;
5a6fe125 289 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
cdfd4325 290 VM_SHARED|VM_NORESERVE))) {
1da177e4 291 charged = nrpages;
191c5424 292 if (security_vm_enough_memory_mm(mm, charged))
1da177e4
LT
293 return -ENOMEM;
294 newflags |= VM_ACCOUNT;
295 }
296 }
297
1da177e4
LT
298 /*
299 * First try to merge with previous and/or next vma.
300 */
301 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
302 *pprev = vma_merge(mm, *pprev, start, end, newflags,
19a809af
AA
303 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
304 vma->vm_userfaultfd_ctx);
1da177e4
LT
305 if (*pprev) {
306 vma = *pprev;
307 goto success;
308 }
309
310 *pprev = vma;
311
312 if (start != vma->vm_start) {
313 error = split_vma(mm, vma, start, 1);
314 if (error)
315 goto fail;
316 }
317
318 if (end != vma->vm_end) {
319 error = split_vma(mm, vma, end, 0);
320 if (error)
321 goto fail;
322 }
323
324success:
325 /*
326 * vm_flags and vm_page_prot are protected by the mmap_sem
327 * held in write mode.
328 */
329 vma->vm_flags = newflags;
64e45507
PF
330 dirty_accountable = vma_wants_writenotify(vma);
331 vma_set_page_prot(vma);
d08b3851 332
7d12efae
AM
333 change_protection(vma, start, end, vma->vm_page_prot,
334 dirty_accountable, 0);
7da4d641 335
36f88188
KS
336 /*
337 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
338 * fault on access.
339 */
340 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
341 (newflags & VM_WRITE)) {
342 populate_vma_page_range(vma, start, end, NULL);
343 }
344
84638335
KK
345 vm_stat_account(mm, oldflags, -nrpages);
346 vm_stat_account(mm, newflags, nrpages);
63bfd738 347 perf_event_mmap(vma);
1da177e4
LT
348 return 0;
349
350fail:
351 vm_unacct_memory(charged);
352 return error;
353}
354
6a6160a7
HC
355SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
356 unsigned long, prot)
1da177e4 357{
62b5f7d0 358 unsigned long nstart, end, tmp, reqprot;
1da177e4
LT
359 struct vm_area_struct *vma, *prev;
360 int error = -EINVAL;
361 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
f138556d
PK
362 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
363 (prot & PROT_READ);
364
1da177e4
LT
365 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
366 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
367 return -EINVAL;
368
369 if (start & ~PAGE_MASK)
370 return -EINVAL;
371 if (!len)
372 return 0;
373 len = PAGE_ALIGN(len);
374 end = start + len;
375 if (end <= start)
376 return -ENOMEM;
b845f313 377 if (!arch_validate_prot(prot))
1da177e4
LT
378 return -EINVAL;
379
380 reqprot = prot;
1da177e4 381
dc0ef0df
MH
382 if (down_write_killable(&current->mm->mmap_sem))
383 return -EINTR;
1da177e4 384
097d5910 385 vma = find_vma(current->mm, start);
1da177e4
LT
386 error = -ENOMEM;
387 if (!vma)
388 goto out;
097d5910 389 prev = vma->vm_prev;
1da177e4
LT
390 if (unlikely(grows & PROT_GROWSDOWN)) {
391 if (vma->vm_start >= end)
392 goto out;
393 start = vma->vm_start;
394 error = -EINVAL;
395 if (!(vma->vm_flags & VM_GROWSDOWN))
396 goto out;
7d12efae 397 } else {
1da177e4
LT
398 if (vma->vm_start > start)
399 goto out;
400 if (unlikely(grows & PROT_GROWSUP)) {
401 end = vma->vm_end;
402 error = -EINVAL;
403 if (!(vma->vm_flags & VM_GROWSUP))
404 goto out;
405 }
406 }
407 if (start > vma->vm_start)
408 prev = vma;
409
410 for (nstart = start ; ; ) {
411 unsigned long newflags;
62b5f7d0 412 int pkey = arch_override_mprotect_pkey(vma, prot, -1);
1da177e4 413
7d12efae 414 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4 415
f138556d
PK
416 /* Does the application expect PROT_READ to imply PROT_EXEC */
417 if (rier && (vma->vm_flags & VM_MAYEXEC))
418 prot |= PROT_EXEC;
419
62b5f7d0 420 newflags = calc_vm_prot_bits(prot, pkey);
7d12efae 421 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
1da177e4 422
7e2cff42
PBG
423 /* newflags >> 4 shift VM_MAY% in place of VM_% */
424 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
1da177e4
LT
425 error = -EACCES;
426 goto out;
427 }
428
429 error = security_file_mprotect(vma, reqprot, prot);
430 if (error)
431 goto out;
432
433 tmp = vma->vm_end;
434 if (tmp > end)
435 tmp = end;
436 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
437 if (error)
438 goto out;
439 nstart = tmp;
440
441 if (nstart < prev->vm_end)
442 nstart = prev->vm_end;
443 if (nstart >= end)
444 goto out;
445
446 vma = prev->vm_next;
447 if (!vma || vma->vm_start != nstart) {
448 error = -ENOMEM;
449 goto out;
450 }
f138556d 451 prot = reqprot;
1da177e4
LT
452 }
453out:
454 up_write(&current->mm->mmap_sem);
455 return error;
456}