Commit | Line | Data |
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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> |
1da177e4 LT |
26 | #include <asm/uaccess.h> |
27 | #include <asm/pgtable.h> | |
28 | #include <asm/cacheflush.h> | |
29 | #include <asm/tlbflush.h> | |
30 | ||
1c12c4cf VP |
31 | #ifndef pgprot_modify |
32 | static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) | |
33 | { | |
34 | return newprot; | |
35 | } | |
36 | #endif | |
37 | ||
7da4d641 | 38 | static unsigned long change_pte_range(struct mm_struct *mm, pmd_t *pmd, |
c1e6098b PZ |
39 | unsigned long addr, unsigned long end, pgprot_t newprot, |
40 | int dirty_accountable) | |
1da177e4 | 41 | { |
0697212a | 42 | pte_t *pte, oldpte; |
705e87c0 | 43 | spinlock_t *ptl; |
7da4d641 | 44 | unsigned long pages = 0; |
1da177e4 | 45 | |
705e87c0 | 46 | pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
6606c3e0 | 47 | arch_enter_lazy_mmu_mode(); |
1da177e4 | 48 | do { |
0697212a CL |
49 | oldpte = *pte; |
50 | if (pte_present(oldpte)) { | |
1da177e4 LT |
51 | pte_t ptent; |
52 | ||
1ea0704e | 53 | ptent = ptep_modify_prot_start(mm, addr, pte); |
c1e6098b | 54 | ptent = pte_modify(ptent, newprot); |
1ea0704e | 55 | |
c1e6098b PZ |
56 | /* |
57 | * Avoid taking write faults for pages we know to be | |
58 | * dirty. | |
59 | */ | |
60 | if (dirty_accountable && pte_dirty(ptent)) | |
61 | ptent = pte_mkwrite(ptent); | |
1ea0704e JF |
62 | |
63 | ptep_modify_prot_commit(mm, addr, pte, ptent); | |
7da4d641 | 64 | pages++; |
ce1744f4 | 65 | } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) { |
0697212a CL |
66 | swp_entry_t entry = pte_to_swp_entry(oldpte); |
67 | ||
68 | if (is_write_migration_entry(entry)) { | |
69 | /* | |
70 | * A protection check is difficult so | |
71 | * just be safe and disable write | |
72 | */ | |
73 | make_migration_entry_read(&entry); | |
74 | set_pte_at(mm, addr, pte, | |
75 | swp_entry_to_pte(entry)); | |
76 | } | |
7da4d641 | 77 | pages++; |
1da177e4 LT |
78 | } |
79 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
6606c3e0 | 80 | arch_leave_lazy_mmu_mode(); |
705e87c0 | 81 | pte_unmap_unlock(pte - 1, ptl); |
7da4d641 PZ |
82 | |
83 | return pages; | |
1da177e4 LT |
84 | } |
85 | ||
7da4d641 | 86 | static inline unsigned long change_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
c1e6098b PZ |
87 | unsigned long addr, unsigned long end, pgprot_t newprot, |
88 | int dirty_accountable) | |
1da177e4 LT |
89 | { |
90 | pmd_t *pmd; | |
91 | unsigned long next; | |
7da4d641 | 92 | unsigned long pages = 0; |
1da177e4 LT |
93 | |
94 | pmd = pmd_offset(pud, addr); | |
95 | do { | |
96 | next = pmd_addr_end(addr, end); | |
cd7548ab JW |
97 | if (pmd_trans_huge(*pmd)) { |
98 | if (next - addr != HPAGE_PMD_SIZE) | |
99 | split_huge_page_pmd(vma->vm_mm, pmd); | |
7da4d641 PZ |
100 | else if (change_huge_pmd(vma, pmd, addr, newprot)) { |
101 | pages += HPAGE_PMD_NR; | |
cd7548ab | 102 | continue; |
7da4d641 | 103 | } |
cd7548ab JW |
104 | /* fall through */ |
105 | } | |
1da177e4 LT |
106 | if (pmd_none_or_clear_bad(pmd)) |
107 | continue; | |
7da4d641 | 108 | pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot, |
b36f5b07 | 109 | dirty_accountable); |
1da177e4 | 110 | } while (pmd++, addr = next, addr != end); |
7da4d641 PZ |
111 | |
112 | return pages; | |
1da177e4 LT |
113 | } |
114 | ||
7da4d641 | 115 | static inline unsigned long change_pud_range(struct vm_area_struct *vma, pgd_t *pgd, |
c1e6098b PZ |
116 | unsigned long addr, unsigned long end, pgprot_t newprot, |
117 | int dirty_accountable) | |
1da177e4 LT |
118 | { |
119 | pud_t *pud; | |
120 | unsigned long next; | |
7da4d641 | 121 | unsigned long pages = 0; |
1da177e4 LT |
122 | |
123 | pud = pud_offset(pgd, addr); | |
124 | do { | |
125 | next = pud_addr_end(addr, end); | |
126 | if (pud_none_or_clear_bad(pud)) | |
127 | continue; | |
7da4d641 | 128 | pages += change_pmd_range(vma, pud, addr, next, newprot, |
b36f5b07 | 129 | dirty_accountable); |
1da177e4 | 130 | } while (pud++, addr = next, addr != end); |
7da4d641 PZ |
131 | |
132 | return pages; | |
1da177e4 LT |
133 | } |
134 | ||
7da4d641 | 135 | static unsigned long change_protection_range(struct vm_area_struct *vma, |
c1e6098b PZ |
136 | unsigned long addr, unsigned long end, pgprot_t newprot, |
137 | int dirty_accountable) | |
1da177e4 LT |
138 | { |
139 | struct mm_struct *mm = vma->vm_mm; | |
140 | pgd_t *pgd; | |
141 | unsigned long next; | |
142 | unsigned long start = addr; | |
7da4d641 | 143 | unsigned long pages = 0; |
1da177e4 LT |
144 | |
145 | BUG_ON(addr >= end); | |
146 | pgd = pgd_offset(mm, addr); | |
147 | flush_cache_range(vma, addr, end); | |
1da177e4 LT |
148 | do { |
149 | next = pgd_addr_end(addr, end); | |
150 | if (pgd_none_or_clear_bad(pgd)) | |
151 | continue; | |
7da4d641 | 152 | pages += change_pud_range(vma, pgd, addr, next, newprot, |
b36f5b07 | 153 | dirty_accountable); |
1da177e4 | 154 | } while (pgd++, addr = next, addr != end); |
7da4d641 | 155 | |
1da177e4 | 156 | flush_tlb_range(vma, start, end); |
7da4d641 PZ |
157 | |
158 | return pages; | |
159 | } | |
160 | ||
161 | unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, | |
162 | unsigned long end, pgprot_t newprot, | |
163 | int dirty_accountable) | |
164 | { | |
165 | struct mm_struct *mm = vma->vm_mm; | |
166 | unsigned long pages; | |
167 | ||
168 | mmu_notifier_invalidate_range_start(mm, start, end); | |
169 | if (is_vm_hugetlb_page(vma)) | |
170 | pages = hugetlb_change_protection(vma, start, end, newprot); | |
171 | else | |
172 | pages = change_protection_range(vma, start, end, newprot, dirty_accountable); | |
173 | mmu_notifier_invalidate_range_end(mm, start, end); | |
174 | ||
175 | return pages; | |
1da177e4 LT |
176 | } |
177 | ||
b6a2fea3 | 178 | int |
1da177e4 LT |
179 | mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, |
180 | unsigned long start, unsigned long end, unsigned long newflags) | |
181 | { | |
182 | struct mm_struct *mm = vma->vm_mm; | |
183 | unsigned long oldflags = vma->vm_flags; | |
184 | long nrpages = (end - start) >> PAGE_SHIFT; | |
185 | unsigned long charged = 0; | |
1da177e4 LT |
186 | pgoff_t pgoff; |
187 | int error; | |
c1e6098b | 188 | int dirty_accountable = 0; |
1da177e4 LT |
189 | |
190 | if (newflags == oldflags) { | |
191 | *pprev = vma; | |
192 | return 0; | |
193 | } | |
194 | ||
195 | /* | |
196 | * If we make a private mapping writable we increase our commit; | |
197 | * but (without finer accounting) cannot reduce our commit if we | |
5a6fe125 MG |
198 | * make it unwritable again. hugetlb mapping were accounted for |
199 | * even if read-only so there is no need to account for them here | |
1da177e4 LT |
200 | */ |
201 | if (newflags & VM_WRITE) { | |
5a6fe125 | 202 | if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| |
cdfd4325 | 203 | VM_SHARED|VM_NORESERVE))) { |
1da177e4 | 204 | charged = nrpages; |
191c5424 | 205 | if (security_vm_enough_memory_mm(mm, charged)) |
1da177e4 LT |
206 | return -ENOMEM; |
207 | newflags |= VM_ACCOUNT; | |
208 | } | |
209 | } | |
210 | ||
1da177e4 LT |
211 | /* |
212 | * First try to merge with previous and/or next vma. | |
213 | */ | |
214 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
215 | *pprev = vma_merge(mm, *pprev, start, end, newflags, | |
216 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); | |
217 | if (*pprev) { | |
218 | vma = *pprev; | |
219 | goto success; | |
220 | } | |
221 | ||
222 | *pprev = vma; | |
223 | ||
224 | if (start != vma->vm_start) { | |
225 | error = split_vma(mm, vma, start, 1); | |
226 | if (error) | |
227 | goto fail; | |
228 | } | |
229 | ||
230 | if (end != vma->vm_end) { | |
231 | error = split_vma(mm, vma, end, 0); | |
232 | if (error) | |
233 | goto fail; | |
234 | } | |
235 | ||
236 | success: | |
237 | /* | |
238 | * vm_flags and vm_page_prot are protected by the mmap_sem | |
239 | * held in write mode. | |
240 | */ | |
241 | vma->vm_flags = newflags; | |
1c12c4cf VP |
242 | vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, |
243 | vm_get_page_prot(newflags)); | |
244 | ||
c1e6098b | 245 | if (vma_wants_writenotify(vma)) { |
1ddd439e | 246 | vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); |
c1e6098b PZ |
247 | dirty_accountable = 1; |
248 | } | |
d08b3851 | 249 | |
7da4d641 PZ |
250 | change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable); |
251 | ||
ab50b8ed HD |
252 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
253 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); | |
63bfd738 | 254 | perf_event_mmap(vma); |
1da177e4 LT |
255 | return 0; |
256 | ||
257 | fail: | |
258 | vm_unacct_memory(charged); | |
259 | return error; | |
260 | } | |
261 | ||
6a6160a7 HC |
262 | SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, |
263 | unsigned long, prot) | |
1da177e4 LT |
264 | { |
265 | unsigned long vm_flags, nstart, end, tmp, reqprot; | |
266 | struct vm_area_struct *vma, *prev; | |
267 | int error = -EINVAL; | |
268 | const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); | |
269 | prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); | |
270 | if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ | |
271 | return -EINVAL; | |
272 | ||
273 | if (start & ~PAGE_MASK) | |
274 | return -EINVAL; | |
275 | if (!len) | |
276 | return 0; | |
277 | len = PAGE_ALIGN(len); | |
278 | end = start + len; | |
279 | if (end <= start) | |
280 | return -ENOMEM; | |
b845f313 | 281 | if (!arch_validate_prot(prot)) |
1da177e4 LT |
282 | return -EINVAL; |
283 | ||
284 | reqprot = prot; | |
285 | /* | |
286 | * Does the application expect PROT_READ to imply PROT_EXEC: | |
287 | */ | |
b344e05c | 288 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
1da177e4 LT |
289 | prot |= PROT_EXEC; |
290 | ||
291 | vm_flags = calc_vm_prot_bits(prot); | |
292 | ||
293 | down_write(¤t->mm->mmap_sem); | |
294 | ||
097d5910 | 295 | vma = find_vma(current->mm, start); |
1da177e4 LT |
296 | error = -ENOMEM; |
297 | if (!vma) | |
298 | goto out; | |
097d5910 | 299 | prev = vma->vm_prev; |
1da177e4 LT |
300 | if (unlikely(grows & PROT_GROWSDOWN)) { |
301 | if (vma->vm_start >= end) | |
302 | goto out; | |
303 | start = vma->vm_start; | |
304 | error = -EINVAL; | |
305 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
306 | goto out; | |
307 | } | |
308 | else { | |
309 | if (vma->vm_start > start) | |
310 | goto out; | |
311 | if (unlikely(grows & PROT_GROWSUP)) { | |
312 | end = vma->vm_end; | |
313 | error = -EINVAL; | |
314 | if (!(vma->vm_flags & VM_GROWSUP)) | |
315 | goto out; | |
316 | } | |
317 | } | |
318 | if (start > vma->vm_start) | |
319 | prev = vma; | |
320 | ||
321 | for (nstart = start ; ; ) { | |
322 | unsigned long newflags; | |
323 | ||
324 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ | |
325 | ||
1da177e4 LT |
326 | newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); |
327 | ||
7e2cff42 PBG |
328 | /* newflags >> 4 shift VM_MAY% in place of VM_% */ |
329 | if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { | |
1da177e4 LT |
330 | error = -EACCES; |
331 | goto out; | |
332 | } | |
333 | ||
334 | error = security_file_mprotect(vma, reqprot, prot); | |
335 | if (error) | |
336 | goto out; | |
337 | ||
338 | tmp = vma->vm_end; | |
339 | if (tmp > end) | |
340 | tmp = end; | |
341 | error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); | |
342 | if (error) | |
343 | goto out; | |
344 | nstart = tmp; | |
345 | ||
346 | if (nstart < prev->vm_end) | |
347 | nstart = prev->vm_end; | |
348 | if (nstart >= end) | |
349 | goto out; | |
350 | ||
351 | vma = prev->vm_next; | |
352 | if (!vma || vma->vm_start != nstart) { | |
353 | error = -ENOMEM; | |
354 | goto out; | |
355 | } | |
356 | } | |
357 | out: | |
358 | up_write(¤t->mm->mmap_sem); | |
359 | return error; | |
360 | } |