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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 <linux/ksm.h>
27#include <linux/pkeys.h>
28#include <asm/uaccess.h>
29#include <asm/pgtable.h>
30#include <asm/cacheflush.h>
31#include <asm/tlbflush.h>
32
33#include "internal.h"
34
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
63static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
64 unsigned long addr, unsigned long end, pgprot_t newprot,
65 int dirty_accountable, int prot_numa)
66{
67 struct mm_struct *mm = vma->vm_mm;
68 pte_t *pte, oldpte;
69 spinlock_t *ptl;
70 unsigned long pages = 0;
71
72 pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
73 if (!pte)
74 return 0;
75
76 arch_enter_lazy_mmu_mode();
77 do {
78 oldpte = *pte;
79 if (pte_present(oldpte)) {
80 pte_t ptent;
81 bool preserve_write = prot_numa && pte_write(oldpte);
82
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;
93
94 /* Avoid TLB flush if possible */
95 if (pte_protnone(oldpte))
96 continue;
97 }
98
99 ptent = ptep_modify_prot_start(mm, addr, pte);
100 ptent = pte_modify(ptent, newprot);
101 if (preserve_write)
102 ptent = pte_mkwrite(ptent);
103
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);
109 }
110 ptep_modify_prot_commit(mm, addr, pte, ptent);
111 pages++;
112 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
113 swp_entry_t entry = pte_to_swp_entry(oldpte);
114
115 if (is_write_migration_entry(entry)) {
116 pte_t newpte;
117 /*
118 * A protection check is difficult so
119 * just be safe and disable write
120 */
121 make_migration_entry_read(&entry);
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);
126
127 pages++;
128 }
129 }
130 } while (pte++, addr += PAGE_SIZE, addr != end);
131 arch_leave_lazy_mmu_mode();
132 pte_unmap_unlock(pte - 1, ptl);
133
134 return pages;
135}
136
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)
140{
141 pmd_t *pmd;
142 struct mm_struct *mm = vma->vm_mm;
143 unsigned long next;
144 unsigned long pages = 0;
145 unsigned long nr_huge_updates = 0;
146 unsigned long mni_start = 0;
147
148 pmd = pmd_offset(pud, addr);
149 do {
150 unsigned long this_pages;
151
152 next = pmd_addr_end(addr, end);
153 if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
154 && pmd_none_or_clear_bad(pmd))
155 continue;
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
163 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
164 if (next - addr != HPAGE_PMD_SIZE) {
165 split_huge_pmd(vma, pmd, addr);
166 if (pmd_none(*pmd))
167 continue;
168 } else {
169 int nr_ptes = change_huge_pmd(vma, pmd, addr,
170 newprot, prot_numa);
171
172 if (nr_ptes) {
173 if (nr_ptes == HPAGE_PMD_NR) {
174 pages += HPAGE_PMD_NR;
175 nr_huge_updates++;
176 }
177
178 /* huge pmd was handled */
179 continue;
180 }
181 }
182 /* fall through, the trans huge pmd just split */
183 }
184 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
185 dirty_accountable, prot_numa);
186 pages += this_pages;
187 } while (pmd++, addr = next, addr != end);
188
189 if (mni_start)
190 mmu_notifier_invalidate_range_end(mm, mni_start, end);
191
192 if (nr_huge_updates)
193 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
194 return pages;
195}
196
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)
200{
201 pud_t *pud;
202 unsigned long next;
203 unsigned long pages = 0;
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;
210 pages += change_pmd_range(vma, pud, addr, next, newprot,
211 dirty_accountable, prot_numa);
212 } while (pud++, addr = next, addr != end);
213
214 return pages;
215}
216
217static unsigned long change_protection_range(struct vm_area_struct *vma,
218 unsigned long addr, unsigned long end, pgprot_t newprot,
219 int dirty_accountable, int prot_numa)
220{
221 struct mm_struct *mm = vma->vm_mm;
222 pgd_t *pgd;
223 unsigned long next;
224 unsigned long start = addr;
225 unsigned long pages = 0;
226
227 BUG_ON(addr >= end);
228 pgd = pgd_offset(mm, addr);
229 flush_cache_range(vma, addr, end);
230 set_tlb_flush_pending(mm);
231 do {
232 next = pgd_addr_end(addr, end);
233 if (pgd_none_or_clear_bad(pgd))
234 continue;
235 pages += change_pud_range(vma, pgd, addr, next, newprot,
236 dirty_accountable, prot_numa);
237 } while (pgd++, addr = next, addr != end);
238
239 /* Only flush the TLB if we actually modified any entries: */
240 if (pages)
241 flush_tlb_range(vma, start, end);
242 clear_tlb_flush_pending(mm);
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,
249 int dirty_accountable, int prot_numa)
250{
251 unsigned long pages;
252
253 if (is_vm_hugetlb_page(vma))
254 pages = hugetlb_change_protection(vma, start, end, newprot);
255 else
256 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
257
258 return pages;
259}
260
261int
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;
269 pgoff_t pgoff;
270 int error;
271 int dirty_accountable = 0;
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
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
283 */
284 if (newflags & VM_WRITE) {
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;
289 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
290 VM_SHARED|VM_NORESERVE))) {
291 charged = nrpages;
292 if (security_vm_enough_memory_mm(mm, charged))
293 return -ENOMEM;
294 newflags |= VM_ACCOUNT;
295 }
296 }
297
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,
303 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
304 vma->vm_userfaultfd_ctx);
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;
330 dirty_accountable = vma_wants_writenotify(vma);
331 vma_set_page_prot(vma);
332
333 change_protection(vma, start, end, vma->vm_page_prot,
334 dirty_accountable, 0);
335
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
345 vm_stat_account(mm, oldflags, -nrpages);
346 vm_stat_account(mm, newflags, nrpages);
347 perf_event_mmap(vma);
348 return 0;
349
350fail:
351 vm_unacct_memory(charged);
352 return error;
353}
354
355SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
356 unsigned long, prot)
357{
358 unsigned long nstart, end, tmp, reqprot;
359 struct vm_area_struct *vma, *prev;
360 int error = -EINVAL;
361 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
362 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
363 (prot & PROT_READ);
364
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;
377 if (!arch_validate_prot(prot))
378 return -EINVAL;
379
380 reqprot = prot;
381
382 down_write(¤t->mm->mmap_sem);
383
384 vma = find_vma(current->mm, start);
385 error = -ENOMEM;
386 if (!vma)
387 goto out;
388 prev = vma->vm_prev;
389 if (unlikely(grows & PROT_GROWSDOWN)) {
390 if (vma->vm_start >= end)
391 goto out;
392 start = vma->vm_start;
393 error = -EINVAL;
394 if (!(vma->vm_flags & VM_GROWSDOWN))
395 goto out;
396 } else {
397 if (vma->vm_start > start)
398 goto out;
399 if (unlikely(grows & PROT_GROWSUP)) {
400 end = vma->vm_end;
401 error = -EINVAL;
402 if (!(vma->vm_flags & VM_GROWSUP))
403 goto out;
404 }
405 }
406 if (start > vma->vm_start)
407 prev = vma;
408
409 for (nstart = start ; ; ) {
410 unsigned long newflags;
411 int pkey = arch_override_mprotect_pkey(vma, prot, -1);
412
413 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
414
415 /* Does the application expect PROT_READ to imply PROT_EXEC */
416 if (rier && (vma->vm_flags & VM_MAYEXEC))
417 prot |= PROT_EXEC;
418
419 newflags = calc_vm_prot_bits(prot, pkey);
420 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
421
422 /* newflags >> 4 shift VM_MAY% in place of VM_% */
423 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
424 error = -EACCES;
425 goto out;
426 }
427
428 error = security_file_mprotect(vma, reqprot, prot);
429 if (error)
430 goto out;
431
432 tmp = vma->vm_end;
433 if (tmp > end)
434 tmp = end;
435 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
436 if (error)
437 goto out;
438 nstart = tmp;
439
440 if (nstart < prev->vm_end)
441 nstart = prev->vm_end;
442 if (nstart >= end)
443 goto out;
444
445 vma = prev->vm_next;
446 if (!vma || vma->vm_start != nstart) {
447 error = -ENOMEM;
448 goto out;
449 }
450 prot = reqprot;
451 }
452out:
453 up_write(¤t->mm->mmap_sem);
454 return error;
455}
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
32static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33{
34 return newprot;
35}
36#endif
37
38static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable)
41{
42 pte_t *pte, oldpte;
43 spinlock_t *ptl;
44
45 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
46 arch_enter_lazy_mmu_mode();
47 do {
48 oldpte = *pte;
49 if (pte_present(oldpte)) {
50 pte_t ptent;
51
52 ptent = ptep_modify_prot_start(mm, addr, pte);
53 ptent = pte_modify(ptent, newprot);
54
55 /*
56 * Avoid taking write faults for pages we know to be
57 * dirty.
58 */
59 if (dirty_accountable && pte_dirty(ptent))
60 ptent = pte_mkwrite(ptent);
61
62 ptep_modify_prot_commit(mm, addr, pte, ptent);
63 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
64 swp_entry_t entry = pte_to_swp_entry(oldpte);
65
66 if (is_write_migration_entry(entry)) {
67 /*
68 * A protection check is difficult so
69 * just be safe and disable write
70 */
71 make_migration_entry_read(&entry);
72 set_pte_at(mm, addr, pte,
73 swp_entry_to_pte(entry));
74 }
75 }
76 } while (pte++, addr += PAGE_SIZE, addr != end);
77 arch_leave_lazy_mmu_mode();
78 pte_unmap_unlock(pte - 1, ptl);
79}
80
81static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
82 unsigned long addr, unsigned long end, pgprot_t newprot,
83 int dirty_accountable)
84{
85 pmd_t *pmd;
86 unsigned long next;
87
88 pmd = pmd_offset(pud, addr);
89 do {
90 next = pmd_addr_end(addr, end);
91 if (pmd_trans_huge(*pmd)) {
92 if (next - addr != HPAGE_PMD_SIZE)
93 split_huge_page_pmd(vma->vm_mm, pmd);
94 else if (change_huge_pmd(vma, pmd, addr, newprot))
95 continue;
96 /* fall through */
97 }
98 if (pmd_none_or_clear_bad(pmd))
99 continue;
100 change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
101 dirty_accountable);
102 } while (pmd++, addr = next, addr != end);
103}
104
105static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
106 unsigned long addr, unsigned long end, pgprot_t newprot,
107 int dirty_accountable)
108{
109 pud_t *pud;
110 unsigned long next;
111
112 pud = pud_offset(pgd, addr);
113 do {
114 next = pud_addr_end(addr, end);
115 if (pud_none_or_clear_bad(pud))
116 continue;
117 change_pmd_range(vma, pud, addr, next, newprot,
118 dirty_accountable);
119 } while (pud++, addr = next, addr != end);
120}
121
122static void change_protection(struct vm_area_struct *vma,
123 unsigned long addr, unsigned long end, pgprot_t newprot,
124 int dirty_accountable)
125{
126 struct mm_struct *mm = vma->vm_mm;
127 pgd_t *pgd;
128 unsigned long next;
129 unsigned long start = addr;
130
131 BUG_ON(addr >= end);
132 pgd = pgd_offset(mm, addr);
133 flush_cache_range(vma, addr, end);
134 do {
135 next = pgd_addr_end(addr, end);
136 if (pgd_none_or_clear_bad(pgd))
137 continue;
138 change_pud_range(vma, pgd, addr, next, newprot,
139 dirty_accountable);
140 } while (pgd++, addr = next, addr != end);
141 flush_tlb_range(vma, start, end);
142}
143
144int
145mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
146 unsigned long start, unsigned long end, unsigned long newflags)
147{
148 struct mm_struct *mm = vma->vm_mm;
149 unsigned long oldflags = vma->vm_flags;
150 long nrpages = (end - start) >> PAGE_SHIFT;
151 unsigned long charged = 0;
152 pgoff_t pgoff;
153 int error;
154 int dirty_accountable = 0;
155
156 if (newflags == oldflags) {
157 *pprev = vma;
158 return 0;
159 }
160
161 /*
162 * If we make a private mapping writable we increase our commit;
163 * but (without finer accounting) cannot reduce our commit if we
164 * make it unwritable again. hugetlb mapping were accounted for
165 * even if read-only so there is no need to account for them here
166 */
167 if (newflags & VM_WRITE) {
168 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
169 VM_SHARED|VM_NORESERVE))) {
170 charged = nrpages;
171 if (security_vm_enough_memory(charged))
172 return -ENOMEM;
173 newflags |= VM_ACCOUNT;
174 }
175 }
176
177 /*
178 * First try to merge with previous and/or next vma.
179 */
180 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
181 *pprev = vma_merge(mm, *pprev, start, end, newflags,
182 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
183 if (*pprev) {
184 vma = *pprev;
185 goto success;
186 }
187
188 *pprev = vma;
189
190 if (start != vma->vm_start) {
191 error = split_vma(mm, vma, start, 1);
192 if (error)
193 goto fail;
194 }
195
196 if (end != vma->vm_end) {
197 error = split_vma(mm, vma, end, 0);
198 if (error)
199 goto fail;
200 }
201
202success:
203 /*
204 * vm_flags and vm_page_prot are protected by the mmap_sem
205 * held in write mode.
206 */
207 vma->vm_flags = newflags;
208 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
209 vm_get_page_prot(newflags));
210
211 if (vma_wants_writenotify(vma)) {
212 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
213 dirty_accountable = 1;
214 }
215
216 mmu_notifier_invalidate_range_start(mm, start, end);
217 if (is_vm_hugetlb_page(vma))
218 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
219 else
220 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
221 mmu_notifier_invalidate_range_end(mm, start, end);
222 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
223 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
224 perf_event_mmap(vma);
225 return 0;
226
227fail:
228 vm_unacct_memory(charged);
229 return error;
230}
231
232SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
233 unsigned long, prot)
234{
235 unsigned long vm_flags, nstart, end, tmp, reqprot;
236 struct vm_area_struct *vma, *prev;
237 int error = -EINVAL;
238 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
239 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
240 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
241 return -EINVAL;
242
243 if (start & ~PAGE_MASK)
244 return -EINVAL;
245 if (!len)
246 return 0;
247 len = PAGE_ALIGN(len);
248 end = start + len;
249 if (end <= start)
250 return -ENOMEM;
251 if (!arch_validate_prot(prot))
252 return -EINVAL;
253
254 reqprot = prot;
255 /*
256 * Does the application expect PROT_READ to imply PROT_EXEC:
257 */
258 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
259 prot |= PROT_EXEC;
260
261 vm_flags = calc_vm_prot_bits(prot);
262
263 down_write(¤t->mm->mmap_sem);
264
265 vma = find_vma_prev(current->mm, start, &prev);
266 error = -ENOMEM;
267 if (!vma)
268 goto out;
269 if (unlikely(grows & PROT_GROWSDOWN)) {
270 if (vma->vm_start >= end)
271 goto out;
272 start = vma->vm_start;
273 error = -EINVAL;
274 if (!(vma->vm_flags & VM_GROWSDOWN))
275 goto out;
276 }
277 else {
278 if (vma->vm_start > start)
279 goto out;
280 if (unlikely(grows & PROT_GROWSUP)) {
281 end = vma->vm_end;
282 error = -EINVAL;
283 if (!(vma->vm_flags & VM_GROWSUP))
284 goto out;
285 }
286 }
287 if (start > vma->vm_start)
288 prev = vma;
289
290 for (nstart = start ; ; ) {
291 unsigned long newflags;
292
293 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
294
295 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
296
297 /* newflags >> 4 shift VM_MAY% in place of VM_% */
298 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
299 error = -EACCES;
300 goto out;
301 }
302
303 error = security_file_mprotect(vma, reqprot, prot);
304 if (error)
305 goto out;
306
307 tmp = vma->vm_end;
308 if (tmp > end)
309 tmp = end;
310 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
311 if (error)
312 goto out;
313 nstart = tmp;
314
315 if (nstart < prev->vm_end)
316 nstart = prev->vm_end;
317 if (nstart >= end)
318 goto out;
319
320 vma = prev->vm_next;
321 if (!vma || vma->vm_start != nstart) {
322 error = -ENOMEM;
323 goto out;
324 }
325 }
326out:
327 up_write(¤t->mm->mmap_sem);
328 return error;
329}