net: fix netlink address dumping in IPv4/IPv6
[linux-2.6.git] / mm / mprotect.c
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/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>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24 #include <linux/mmu_notifier.h>
25 #include <linux/migrate.h>
26 #include <linux/perf_event.h>
27 #include <asm/uaccess.h>
28 #include <asm/pgtable.h>
29 #include <asm/cacheflush.h>
30 #include <asm/tlbflush.h>
31
32 #ifndef pgprot_modify
33 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
34 {
35         return newprot;
36 }
37 #endif
38
39 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
40                 unsigned long addr, unsigned long end, pgprot_t newprot,
41                 int dirty_accountable)
42 {
43         pte_t *pte, oldpte;
44         spinlock_t *ptl;
45
46         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
47         arch_enter_lazy_mmu_mode();
48         do {
49                 oldpte = *pte;
50                 if (pte_present(oldpte)) {
51                         pte_t ptent;
52
53                         ptent = ptep_modify_prot_start(mm, addr, pte);
54                         ptent = pte_modify(ptent, newprot);
55
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);
62
63                         ptep_modify_prot_commit(mm, addr, pte, ptent);
64                 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
65                         swp_entry_t entry = pte_to_swp_entry(oldpte);
66
67                         if (is_write_migration_entry(entry)) {
68                                 /*
69                                  * A protection check is difficult so
70                                  * just be safe and disable write
71                                  */
72                                 make_migration_entry_read(&entry);
73                                 set_pte_at(mm, addr, pte,
74                                         swp_entry_to_pte(entry));
75                         }
76                 }
77         } while (pte++, addr += PAGE_SIZE, addr != end);
78         arch_leave_lazy_mmu_mode();
79         pte_unmap_unlock(pte - 1, ptl);
80 }
81
82 static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
83                 unsigned long addr, unsigned long end, pgprot_t newprot,
84                 int dirty_accountable)
85 {
86         pmd_t *pmd;
87         unsigned long next;
88
89         pmd = pmd_offset(pud, addr);
90         do {
91                 next = pmd_addr_end(addr, end);
92                 if (pmd_none_or_clear_bad(pmd))
93                         continue;
94                 change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
95         } while (pmd++, addr = next, addr != end);
96 }
97
98 static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
99                 unsigned long addr, unsigned long end, pgprot_t newprot,
100                 int dirty_accountable)
101 {
102         pud_t *pud;
103         unsigned long next;
104
105         pud = pud_offset(pgd, addr);
106         do {
107                 next = pud_addr_end(addr, end);
108                 if (pud_none_or_clear_bad(pud))
109                         continue;
110                 change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
111         } while (pud++, addr = next, addr != end);
112 }
113
114 static void change_protection(struct vm_area_struct *vma,
115                 unsigned long addr, unsigned long end, pgprot_t newprot,
116                 int dirty_accountable)
117 {
118         struct mm_struct *mm = vma->vm_mm;
119         pgd_t *pgd;
120         unsigned long next;
121         unsigned long start = addr;
122
123         BUG_ON(addr >= end);
124         pgd = pgd_offset(mm, addr);
125         flush_cache_range(vma, addr, end);
126         do {
127                 next = pgd_addr_end(addr, end);
128                 if (pgd_none_or_clear_bad(pgd))
129                         continue;
130                 change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
131         } while (pgd++, addr = next, addr != end);
132         flush_tlb_range(vma, start, end);
133 }
134
135 int
136 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
137         unsigned long start, unsigned long end, unsigned long newflags)
138 {
139         struct mm_struct *mm = vma->vm_mm;
140         unsigned long oldflags = vma->vm_flags;
141         long nrpages = (end - start) >> PAGE_SHIFT;
142         unsigned long charged = 0;
143         pgoff_t pgoff;
144         int error;
145         int dirty_accountable = 0;
146
147         if (newflags == oldflags) {
148                 *pprev = vma;
149                 return 0;
150         }
151
152         /*
153          * If we make a private mapping writable we increase our commit;
154          * but (without finer accounting) cannot reduce our commit if we
155          * make it unwritable again. hugetlb mapping were accounted for
156          * even if read-only so there is no need to account for them here
157          */
158         if (newflags & VM_WRITE) {
159                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
160                                                 VM_SHARED|VM_NORESERVE))) {
161                         charged = nrpages;
162                         if (security_vm_enough_memory(charged))
163                                 return -ENOMEM;
164                         newflags |= VM_ACCOUNT;
165                 }
166         }
167
168         /*
169          * First try to merge with previous and/or next vma.
170          */
171         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
172         *pprev = vma_merge(mm, *pprev, start, end, newflags,
173                         vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
174         if (*pprev) {
175                 vma = *pprev;
176                 goto success;
177         }
178
179         *pprev = vma;
180
181         if (start != vma->vm_start) {
182                 error = split_vma(mm, vma, start, 1);
183                 if (error)
184                         goto fail;
185         }
186
187         if (end != vma->vm_end) {
188                 error = split_vma(mm, vma, end, 0);
189                 if (error)
190                         goto fail;
191         }
192
193 success:
194         /*
195          * vm_flags and vm_page_prot are protected by the mmap_sem
196          * held in write mode.
197          */
198         vma->vm_flags = newflags;
199         vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
200                                           vm_get_page_prot(newflags));
201
202         if (vma_wants_writenotify(vma)) {
203                 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
204                 dirty_accountable = 1;
205         }
206
207         mmu_notifier_invalidate_range_start(mm, start, end);
208         if (is_vm_hugetlb_page(vma))
209                 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
210         else
211                 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
212         mmu_notifier_invalidate_range_end(mm, start, end);
213         vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
214         vm_stat_account(mm, newflags, vma->vm_file, nrpages);
215         return 0;
216
217 fail:
218         vm_unacct_memory(charged);
219         return error;
220 }
221
222 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
223                 unsigned long, prot)
224 {
225         unsigned long vm_flags, nstart, end, tmp, reqprot;
226         struct vm_area_struct *vma, *prev;
227         int error = -EINVAL;
228         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
229         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
230         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
231                 return -EINVAL;
232
233         if (start & ~PAGE_MASK)
234                 return -EINVAL;
235         if (!len)
236                 return 0;
237         len = PAGE_ALIGN(len);
238         end = start + len;
239         if (end <= start)
240                 return -ENOMEM;
241         if (!arch_validate_prot(prot))
242                 return -EINVAL;
243
244         reqprot = prot;
245         /*
246          * Does the application expect PROT_READ to imply PROT_EXEC:
247          */
248         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
249                 prot |= PROT_EXEC;
250
251         vm_flags = calc_vm_prot_bits(prot);
252
253         down_write(&current->mm->mmap_sem);
254
255         vma = find_vma_prev(current->mm, start, &prev);
256         error = -ENOMEM;
257         if (!vma)
258                 goto out;
259         if (unlikely(grows & PROT_GROWSDOWN)) {
260                 if (vma->vm_start >= end)
261                         goto out;
262                 start = vma->vm_start;
263                 error = -EINVAL;
264                 if (!(vma->vm_flags & VM_GROWSDOWN))
265                         goto out;
266         }
267         else {
268                 if (vma->vm_start > start)
269                         goto out;
270                 if (unlikely(grows & PROT_GROWSUP)) {
271                         end = vma->vm_end;
272                         error = -EINVAL;
273                         if (!(vma->vm_flags & VM_GROWSUP))
274                                 goto out;
275                 }
276         }
277         if (start > vma->vm_start)
278                 prev = vma;
279
280         for (nstart = start ; ; ) {
281                 unsigned long newflags;
282
283                 /* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
284
285                 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
286
287                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
288                 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
289                         error = -EACCES;
290                         goto out;
291                 }
292
293                 error = security_file_mprotect(vma, reqprot, prot);
294                 if (error)
295                         goto out;
296
297                 tmp = vma->vm_end;
298                 if (tmp > end)
299                         tmp = end;
300                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
301                 if (error)
302                         goto out;
303                 perf_event_mmap(vma);
304                 nstart = tmp;
305
306                 if (nstart < prev->vm_end)
307                         nstart = prev->vm_end;
308                 if (nstart >= end)
309                         goto out;
310
311                 vma = prev->vm_next;
312                 if (!vma || vma->vm_start != nstart) {
313                         error = -ENOMEM;
314                         goto out;
315                 }
316         }
317 out:
318         up_write(&current->mm->mmap_sem);
319         return error;
320 }