blob: abe2694e13f497ea8ecaa443fa6d7d11a5edb084 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/mprotect.c
3 *
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 *
Alan Cox046c6882009-01-05 14:06:29 +00007 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 * (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>
Christoph Lameter06972122006-06-23 02:03:35 -070022#include <linux/swap.h>
23#include <linux/swapops.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070024#include <linux/mmu_notifier.h>
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -080025#include <linux/migrate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <asm/uaccess.h>
27#include <asm/pgtable.h>
28#include <asm/cacheflush.h>
29#include <asm/tlbflush.h>
30
Venki Pallipadi1c12c4c2008-05-14 16:05:51 -070031#ifndef pgprot_modify
32static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33{
34 return newprot;
35}
36#endif
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
Peter Zijlstrac1e60982006-09-25 23:30:59 -070039 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable)
Linus Torvalds1da177e2005-04-16 15:20:36 -070041{
Christoph Lameter06972122006-06-23 02:03:35 -070042 pte_t *pte, oldpte;
Hugh Dickins705e87c2005-10-29 18:16:27 -070043 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Hugh Dickins705e87c2005-10-29 18:16:27 -070045 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
Zachary Amsden6606c3e2006-09-30 23:29:33 -070046 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -070047 do {
Christoph Lameter06972122006-06-23 02:03:35 -070048 oldpte = *pte;
49 if (pte_present(oldpte)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 pte_t ptent;
51
Jeremy Fitzhardinge1ea07042008-06-16 04:30:00 -070052 ptent = ptep_modify_prot_start(mm, addr, pte);
Peter Zijlstrac1e60982006-09-25 23:30:59 -070053 ptent = pte_modify(ptent, newprot);
Jeremy Fitzhardinge1ea07042008-06-16 04:30:00 -070054
Peter Zijlstrac1e60982006-09-25 23:30:59 -070055 /*
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);
Jeremy Fitzhardinge1ea07042008-06-16 04:30:00 -070061
62 ptep_modify_prot_commit(mm, addr, pte, ptent);
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -080063 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
Christoph Lameter06972122006-06-23 02:03:35 -070064 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 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 }
76 } while (pte++, addr += PAGE_SIZE, addr != end);
Zachary Amsden6606c3e2006-09-30 23:29:33 -070077 arch_leave_lazy_mmu_mode();
Hugh Dickins705e87c2005-10-29 18:16:27 -070078 pte_unmap_unlock(pte - 1, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -070079}
80
81static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
Peter Zijlstrac1e60982006-09-25 23:30:59 -070082 unsigned long addr, unsigned long end, pgprot_t newprot,
83 int dirty_accountable)
Linus Torvalds1da177e2005-04-16 15:20:36 -070084{
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;
Peter Zijlstrac1e60982006-09-25 23:30:59 -070093 change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 } while (pmd++, addr = next, addr != end);
95}
96
97static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
Peter Zijlstrac1e60982006-09-25 23:30:59 -070098 unsigned long addr, unsigned long end, pgprot_t newprot,
99 int dirty_accountable)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
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;
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700109 change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 } while (pud++, addr = next, addr != end);
111}
112
113static void change_protection(struct vm_area_struct *vma,
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700114 unsigned long addr, unsigned long end, pgprot_t newprot,
115 int dirty_accountable)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116{
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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125 do {
126 next = pgd_addr_end(addr, end);
127 if (pgd_none_or_clear_bad(pgd))
128 continue;
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700129 change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 } while (pgd++, addr = next, addr != end);
131 flush_tlb_range(vma, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132}
133
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700134int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135mprotect_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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 pgoff_t pgoff;
143 int error;
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700144 int dirty_accountable = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
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.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 */
156 if (newflags & VM_WRITE) {
Andy Whitcroftcdfd4322008-07-23 21:27:28 -0700157 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|
158 VM_SHARED|VM_NORESERVE))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 charged = nrpages;
160 if (security_vm_enough_memory(charged))
161 return -ENOMEM;
162 newflags |= VM_ACCOUNT;
163 }
164 }
165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 /*
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
191success:
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;
Venki Pallipadi1c12c4c2008-05-14 16:05:51 -0700197 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
198 vm_get_page_prot(newflags));
199
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700200 if (vma_wants_writenotify(vma)) {
Hugh Dickins1ddd4392007-10-22 20:45:12 -0700201 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700202 dirty_accountable = 1;
203 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700204
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700205 mmu_notifier_invalidate_range_start(mm, start, end);
Zhang, Yanmin8f860592006-03-22 00:08:50 -0800206 if (is_vm_hugetlb_page(vma))
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700207 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
Zhang, Yanmin8f860592006-03-22 00:08:50 -0800208 else
Peter Zijlstrac1e60982006-09-25 23:30:59 -0700209 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700210 mmu_notifier_invalidate_range_end(mm, start, end);
Hugh Dickinsab50b8e2005-10-29 18:15:56 -0700211 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
212 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 return 0;
214
215fail:
216 vm_unacct_memory(charged);
217 return error;
218}
219
Heiko Carstens6a6160a2009-01-14 14:14:15 +0100220SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
221 unsigned long, prot)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222{
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;
Dave Kleikampb845f312008-07-08 00:28:51 +1000239 if (!arch_validate_prot(prot))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 return -EINVAL;
241
242 reqprot = prot;
243 /*
244 * Does the application expect PROT_READ to imply PROT_EXEC:
245 */
Hua Zhongb344e052006-06-23 02:03:23 -0700246 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 prot |= PROT_EXEC;
248
249 vm_flags = calc_vm_prot_bits(prot);
250
251 down_write(&current->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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
284
Paolo 'Blaisorblade' Giarrusso7e2cff42005-09-21 09:55:39 -0700285 /* newflags >> 4 shift VM_MAY% in place of VM_% */
286 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 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 }
314out:
315 up_write(&current->mm->mmap_sem);
316 return error;
317}