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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> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/shm.h> | |
15 | #include <linux/mman.h> | |
16 | #include <linux/fs.h> | |
17 | #include <linux/highmem.h> | |
18 | #include <linux/security.h> | |
19 | #include <linux/mempolicy.h> | |
20 | #include <linux/personality.h> | |
21 | #include <linux/syscalls.h> | |
0697212a CL |
22 | #include <linux/swap.h> |
23 | #include <linux/swapops.h> | |
cddb8a5c | 24 | #include <linux/mmu_notifier.h> |
64cdd548 | 25 | #include <linux/migrate.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 | ||
1da177e4 | 38 | static void 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; |
1da177e4 | 44 | |
705e87c0 | 45 | pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
6606c3e0 | 46 | arch_enter_lazy_mmu_mode(); |
1da177e4 | 47 | do { |
0697212a CL |
48 | oldpte = *pte; |
49 | if (pte_present(oldpte)) { | |
1da177e4 LT |
50 | pte_t ptent; |
51 | ||
1ea0704e | 52 | ptent = ptep_modify_prot_start(mm, addr, pte); |
c1e6098b | 53 | ptent = pte_modify(ptent, newprot); |
1ea0704e | 54 | |
c1e6098b PZ |
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); | |
1ea0704e JF |
61 | |
62 | ptep_modify_prot_commit(mm, addr, pte, ptent); | |
64cdd548 | 63 | } else if (PAGE_MIGRATION && !pte_file(oldpte)) { |
0697212a CL |
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 | } | |
1da177e4 LT |
75 | } |
76 | } while (pte++, addr += PAGE_SIZE, addr != end); | |
6606c3e0 | 77 | arch_leave_lazy_mmu_mode(); |
705e87c0 | 78 | pte_unmap_unlock(pte - 1, ptl); |
1da177e4 LT |
79 | } |
80 | ||
81 | static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, | |
c1e6098b PZ |
82 | unsigned long addr, unsigned long end, pgprot_t newprot, |
83 | int dirty_accountable) | |
1da177e4 LT |
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_none_or_clear_bad(pmd)) | |
92 | continue; | |
c1e6098b | 93 | change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable); |
1da177e4 LT |
94 | } while (pmd++, addr = next, addr != end); |
95 | } | |
96 | ||
97 | static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, | |
c1e6098b PZ |
98 | unsigned long addr, unsigned long end, pgprot_t newprot, |
99 | int dirty_accountable) | |
1da177e4 LT |
100 | { |
101 | pud_t *pud; | |
102 | unsigned long next; | |
103 | ||
104 | pud = pud_offset(pgd, addr); | |
105 | do { | |
106 | next = pud_addr_end(addr, end); | |
107 | if (pud_none_or_clear_bad(pud)) | |
108 | continue; | |
c1e6098b | 109 | change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable); |
1da177e4 LT |
110 | } while (pud++, addr = next, addr != end); |
111 | } | |
112 | ||
113 | static void change_protection(struct vm_area_struct *vma, | |
c1e6098b PZ |
114 | unsigned long addr, unsigned long end, pgprot_t newprot, |
115 | int dirty_accountable) | |
1da177e4 LT |
116 | { |
117 | struct mm_struct *mm = vma->vm_mm; | |
118 | pgd_t *pgd; | |
119 | unsigned long next; | |
120 | unsigned long start = addr; | |
121 | ||
122 | BUG_ON(addr >= end); | |
123 | pgd = pgd_offset(mm, addr); | |
124 | flush_cache_range(vma, addr, end); | |
1da177e4 LT |
125 | do { |
126 | next = pgd_addr_end(addr, end); | |
127 | if (pgd_none_or_clear_bad(pgd)) | |
128 | continue; | |
c1e6098b | 129 | change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable); |
1da177e4 LT |
130 | } while (pgd++, addr = next, addr != end); |
131 | flush_tlb_range(vma, start, end); | |
1da177e4 LT |
132 | } |
133 | ||
b6a2fea3 | 134 | int |
1da177e4 LT |
135 | mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, |
136 | unsigned long start, unsigned long end, unsigned long newflags) | |
137 | { | |
138 | struct mm_struct *mm = vma->vm_mm; | |
139 | unsigned long oldflags = vma->vm_flags; | |
140 | long nrpages = (end - start) >> PAGE_SHIFT; | |
141 | unsigned long charged = 0; | |
1da177e4 LT |
142 | pgoff_t pgoff; |
143 | int error; | |
c1e6098b | 144 | int dirty_accountable = 0; |
1da177e4 LT |
145 | |
146 | if (newflags == oldflags) { | |
147 | *pprev = vma; | |
148 | return 0; | |
149 | } | |
150 | ||
151 | /* | |
152 | * If we make a private mapping writable we increase our commit; | |
153 | * but (without finer accounting) cannot reduce our commit if we | |
154 | * make it unwritable again. | |
1da177e4 LT |
155 | */ |
156 | if (newflags & VM_WRITE) { | |
cdfd4325 AW |
157 | if (!(oldflags & (VM_ACCOUNT|VM_WRITE| |
158 | VM_SHARED|VM_NORESERVE))) { | |
1da177e4 LT |
159 | charged = nrpages; |
160 | if (security_vm_enough_memory(charged)) | |
161 | return -ENOMEM; | |
162 | newflags |= VM_ACCOUNT; | |
163 | } | |
164 | } | |
165 | ||
1da177e4 LT |
166 | /* |
167 | * First try to merge with previous and/or next vma. | |
168 | */ | |
169 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
170 | *pprev = vma_merge(mm, *pprev, start, end, newflags, | |
171 | vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); | |
172 | if (*pprev) { | |
173 | vma = *pprev; | |
174 | goto success; | |
175 | } | |
176 | ||
177 | *pprev = vma; | |
178 | ||
179 | if (start != vma->vm_start) { | |
180 | error = split_vma(mm, vma, start, 1); | |
181 | if (error) | |
182 | goto fail; | |
183 | } | |
184 | ||
185 | if (end != vma->vm_end) { | |
186 | error = split_vma(mm, vma, end, 0); | |
187 | if (error) | |
188 | goto fail; | |
189 | } | |
190 | ||
191 | success: | |
192 | /* | |
193 | * vm_flags and vm_page_prot are protected by the mmap_sem | |
194 | * held in write mode. | |
195 | */ | |
196 | vma->vm_flags = newflags; | |
1c12c4cf VP |
197 | vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, |
198 | vm_get_page_prot(newflags)); | |
199 | ||
c1e6098b | 200 | if (vma_wants_writenotify(vma)) { |
1ddd439e | 201 | vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); |
c1e6098b PZ |
202 | dirty_accountable = 1; |
203 | } | |
d08b3851 | 204 | |
cddb8a5c | 205 | mmu_notifier_invalidate_range_start(mm, start, end); |
8f860591 | 206 | if (is_vm_hugetlb_page(vma)) |
d08b3851 | 207 | hugetlb_change_protection(vma, start, end, vma->vm_page_prot); |
8f860591 | 208 | else |
c1e6098b | 209 | change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable); |
cddb8a5c | 210 | mmu_notifier_invalidate_range_end(mm, start, end); |
ab50b8ed HD |
211 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
212 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); | |
1da177e4 LT |
213 | return 0; |
214 | ||
215 | fail: | |
216 | vm_unacct_memory(charged); | |
217 | return error; | |
218 | } | |
219 | ||
220 | asmlinkage long | |
221 | sys_mprotect(unsigned long start, size_t len, unsigned long prot) | |
222 | { | |
223 | unsigned long vm_flags, nstart, end, tmp, reqprot; | |
224 | struct vm_area_struct *vma, *prev; | |
225 | int error = -EINVAL; | |
226 | const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); | |
227 | prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); | |
228 | if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ | |
229 | return -EINVAL; | |
230 | ||
231 | if (start & ~PAGE_MASK) | |
232 | return -EINVAL; | |
233 | if (!len) | |
234 | return 0; | |
235 | len = PAGE_ALIGN(len); | |
236 | end = start + len; | |
237 | if (end <= start) | |
238 | return -ENOMEM; | |
b845f313 | 239 | if (!arch_validate_prot(prot)) |
1da177e4 LT |
240 | return -EINVAL; |
241 | ||
242 | reqprot = prot; | |
243 | /* | |
244 | * Does the application expect PROT_READ to imply PROT_EXEC: | |
245 | */ | |
b344e05c | 246 | if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
1da177e4 LT |
247 | prot |= PROT_EXEC; |
248 | ||
249 | vm_flags = calc_vm_prot_bits(prot); | |
250 | ||
251 | down_write(¤t->mm->mmap_sem); | |
252 | ||
253 | vma = find_vma_prev(current->mm, start, &prev); | |
254 | error = -ENOMEM; | |
255 | if (!vma) | |
256 | goto out; | |
257 | if (unlikely(grows & PROT_GROWSDOWN)) { | |
258 | if (vma->vm_start >= end) | |
259 | goto out; | |
260 | start = vma->vm_start; | |
261 | error = -EINVAL; | |
262 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
263 | goto out; | |
264 | } | |
265 | else { | |
266 | if (vma->vm_start > start) | |
267 | goto out; | |
268 | if (unlikely(grows & PROT_GROWSUP)) { | |
269 | end = vma->vm_end; | |
270 | error = -EINVAL; | |
271 | if (!(vma->vm_flags & VM_GROWSUP)) | |
272 | goto out; | |
273 | } | |
274 | } | |
275 | if (start > vma->vm_start) | |
276 | prev = vma; | |
277 | ||
278 | for (nstart = start ; ; ) { | |
279 | unsigned long newflags; | |
280 | ||
281 | /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ | |
282 | ||
1da177e4 LT |
283 | newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); |
284 | ||
7e2cff42 PBG |
285 | /* newflags >> 4 shift VM_MAY% in place of VM_% */ |
286 | if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) { | |
1da177e4 LT |
287 | error = -EACCES; |
288 | goto out; | |
289 | } | |
290 | ||
291 | error = security_file_mprotect(vma, reqprot, prot); | |
292 | if (error) | |
293 | goto out; | |
294 | ||
295 | tmp = vma->vm_end; | |
296 | if (tmp > end) | |
297 | tmp = end; | |
298 | error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); | |
299 | if (error) | |
300 | goto out; | |
301 | nstart = tmp; | |
302 | ||
303 | if (nstart < prev->vm_end) | |
304 | nstart = prev->vm_end; | |
305 | if (nstart >= end) | |
306 | goto out; | |
307 | ||
308 | vma = prev->vm_next; | |
309 | if (!vma || vma->vm_start != nstart) { | |
310 | error = -ENOMEM; | |
311 | goto out; | |
312 | } | |
313 | } | |
314 | out: | |
315 | up_write(¤t->mm->mmap_sem); | |
316 | return error; | |
317 | } |