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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// SPDX-License-Identifier: GPL-2.0
2/*
3 * mm/mprotect.c
4 *
5 * (C) Copyright 1994 Linus Torvalds
6 * (C) Copyright 2002 Christoph Hellwig
7 *
8 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
10 */
11
12#include <linux/pagewalk.h>
13#include <linux/hugetlb.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 <linux/pkeys.h>
28#include <linux/ksm.h>
29#include <linux/uaccess.h>
30#include <linux/mm_inline.h>
31#include <linux/pgtable.h>
32#include <linux/sched/sysctl.h>
33#include <linux/userfaultfd_k.h>
34#include <linux/memory-tiers.h>
35#include <asm/cacheflush.h>
36#include <asm/mmu_context.h>
37#include <asm/tlbflush.h>
38#include <asm/tlb.h>
39
40#include "internal.h"
41
42bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
43 pte_t pte)
44{
45 struct page *page;
46
47 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
48 return false;
49
50 /* Don't touch entries that are not even readable. */
51 if (pte_protnone(pte))
52 return false;
53
54 /* Do we need write faults for softdirty tracking? */
55 if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
56 return false;
57
58 /* Do we need write faults for uffd-wp tracking? */
59 if (userfaultfd_pte_wp(vma, pte))
60 return false;
61
62 if (!(vma->vm_flags & VM_SHARED)) {
63 /*
64 * Writable MAP_PRIVATE mapping: We can only special-case on
65 * exclusive anonymous pages, because we know that our
66 * write-fault handler similarly would map them writable without
67 * any additional checks while holding the PT lock.
68 */
69 page = vm_normal_page(vma, addr, pte);
70 return page && PageAnon(page) && PageAnonExclusive(page);
71 }
72
73 /*
74 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
75 * needs a real write-fault for writenotify
76 * (see vma_wants_writenotify()). If "dirty", the assumption is that the
77 * FS was already notified and we can simply mark the PTE writable
78 * just like the write-fault handler would do.
79 */
80 return pte_dirty(pte);
81}
82
83static unsigned long change_pte_range(struct mmu_gather *tlb,
84 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
85 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
86{
87 pte_t *pte, oldpte;
88 spinlock_t *ptl;
89 unsigned long pages = 0;
90 int target_node = NUMA_NO_NODE;
91 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
92 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
93 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
94
95 tlb_change_page_size(tlb, PAGE_SIZE);
96
97 /*
98 * Can be called with only the mmap_lock for reading by
99 * prot_numa so we must check the pmd isn't constantly
100 * changing from under us from pmd_none to pmd_trans_huge
101 * and/or the other way around.
102 */
103 if (pmd_trans_unstable(pmd))
104 return 0;
105
106 /*
107 * The pmd points to a regular pte so the pmd can't change
108 * from under us even if the mmap_lock is only hold for
109 * reading.
110 */
111 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
112
113 /* Get target node for single threaded private VMAs */
114 if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
115 atomic_read(&vma->vm_mm->mm_users) == 1)
116 target_node = numa_node_id();
117
118 flush_tlb_batched_pending(vma->vm_mm);
119 arch_enter_lazy_mmu_mode();
120 do {
121 oldpte = *pte;
122 if (pte_present(oldpte)) {
123 pte_t ptent;
124
125 /*
126 * Avoid trapping faults against the zero or KSM
127 * pages. See similar comment in change_huge_pmd.
128 */
129 if (prot_numa) {
130 struct page *page;
131 int nid;
132 bool toptier;
133
134 /* Avoid TLB flush if possible */
135 if (pte_protnone(oldpte))
136 continue;
137
138 page = vm_normal_page(vma, addr, oldpte);
139 if (!page || is_zone_device_page(page) || PageKsm(page))
140 continue;
141
142 /* Also skip shared copy-on-write pages */
143 if (is_cow_mapping(vma->vm_flags) &&
144 page_count(page) != 1)
145 continue;
146
147 /*
148 * While migration can move some dirty pages,
149 * it cannot move them all from MIGRATE_ASYNC
150 * context.
151 */
152 if (page_is_file_lru(page) && PageDirty(page))
153 continue;
154
155 /*
156 * Don't mess with PTEs if page is already on the node
157 * a single-threaded process is running on.
158 */
159 nid = page_to_nid(page);
160 if (target_node == nid)
161 continue;
162 toptier = node_is_toptier(nid);
163
164 /*
165 * Skip scanning top tier node if normal numa
166 * balancing is disabled
167 */
168 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
169 toptier)
170 continue;
171 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
172 !toptier)
173 xchg_page_access_time(page,
174 jiffies_to_msecs(jiffies));
175 }
176
177 oldpte = ptep_modify_prot_start(vma, addr, pte);
178 ptent = pte_modify(oldpte, newprot);
179
180 if (uffd_wp) {
181 ptent = pte_wrprotect(ptent);
182 ptent = pte_mkuffd_wp(ptent);
183 } else if (uffd_wp_resolve) {
184 ptent = pte_clear_uffd_wp(ptent);
185 }
186
187 /*
188 * In some writable, shared mappings, we might want
189 * to catch actual write access -- see
190 * vma_wants_writenotify().
191 *
192 * In all writable, private mappings, we have to
193 * properly handle COW.
194 *
195 * In both cases, we can sometimes still change PTEs
196 * writable and avoid the write-fault handler, for
197 * example, if a PTE is already dirty and no other
198 * COW or special handling is required.
199 */
200 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
201 !pte_write(ptent) &&
202 can_change_pte_writable(vma, addr, ptent))
203 ptent = pte_mkwrite(ptent);
204
205 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
206 if (pte_needs_flush(oldpte, ptent))
207 tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
208 pages++;
209 } else if (is_swap_pte(oldpte)) {
210 swp_entry_t entry = pte_to_swp_entry(oldpte);
211 pte_t newpte;
212
213 if (is_writable_migration_entry(entry)) {
214 struct page *page = pfn_swap_entry_to_page(entry);
215
216 /*
217 * A protection check is difficult so
218 * just be safe and disable write
219 */
220 if (PageAnon(page))
221 entry = make_readable_exclusive_migration_entry(
222 swp_offset(entry));
223 else
224 entry = make_readable_migration_entry(swp_offset(entry));
225 newpte = swp_entry_to_pte(entry);
226 if (pte_swp_soft_dirty(oldpte))
227 newpte = pte_swp_mksoft_dirty(newpte);
228 if (pte_swp_uffd_wp(oldpte))
229 newpte = pte_swp_mkuffd_wp(newpte);
230 } else if (is_writable_device_private_entry(entry)) {
231 /*
232 * We do not preserve soft-dirtiness. See
233 * copy_one_pte() for explanation.
234 */
235 entry = make_readable_device_private_entry(
236 swp_offset(entry));
237 newpte = swp_entry_to_pte(entry);
238 if (pte_swp_uffd_wp(oldpte))
239 newpte = pte_swp_mkuffd_wp(newpte);
240 } else if (is_writable_device_exclusive_entry(entry)) {
241 entry = make_readable_device_exclusive_entry(
242 swp_offset(entry));
243 newpte = swp_entry_to_pte(entry);
244 if (pte_swp_soft_dirty(oldpte))
245 newpte = pte_swp_mksoft_dirty(newpte);
246 if (pte_swp_uffd_wp(oldpte))
247 newpte = pte_swp_mkuffd_wp(newpte);
248 } else if (is_pte_marker_entry(entry)) {
249 /*
250 * Ignore swapin errors unconditionally,
251 * because any access should sigbus anyway.
252 */
253 if (is_swapin_error_entry(entry))
254 continue;
255 /*
256 * If this is uffd-wp pte marker and we'd like
257 * to unprotect it, drop it; the next page
258 * fault will trigger without uffd trapping.
259 */
260 if (uffd_wp_resolve) {
261 pte_clear(vma->vm_mm, addr, pte);
262 pages++;
263 }
264 continue;
265 } else {
266 newpte = oldpte;
267 }
268
269 if (uffd_wp)
270 newpte = pte_swp_mkuffd_wp(newpte);
271 else if (uffd_wp_resolve)
272 newpte = pte_swp_clear_uffd_wp(newpte);
273
274 if (!pte_same(oldpte, newpte)) {
275 set_pte_at(vma->vm_mm, addr, pte, newpte);
276 pages++;
277 }
278 } else {
279 /* It must be an none page, or what else?.. */
280 WARN_ON_ONCE(!pte_none(oldpte));
281 if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {
282 /*
283 * For file-backed mem, we need to be able to
284 * wr-protect a none pte, because even if the
285 * pte is none, the page/swap cache could
286 * exist. Doing that by install a marker.
287 */
288 set_pte_at(vma->vm_mm, addr, pte,
289 make_pte_marker(PTE_MARKER_UFFD_WP));
290 pages++;
291 }
292 }
293 } while (pte++, addr += PAGE_SIZE, addr != end);
294 arch_leave_lazy_mmu_mode();
295 pte_unmap_unlock(pte - 1, ptl);
296
297 return pages;
298}
299
300/*
301 * Used when setting automatic NUMA hinting protection where it is
302 * critical that a numa hinting PMD is not confused with a bad PMD.
303 */
304static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
305{
306 pmd_t pmdval = pmdp_get_lockless(pmd);
307
308 /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
309#ifdef CONFIG_TRANSPARENT_HUGEPAGE
310 barrier();
311#endif
312
313 if (pmd_none(pmdval))
314 return 1;
315 if (pmd_trans_huge(pmdval))
316 return 0;
317 if (unlikely(pmd_bad(pmdval))) {
318 pmd_clear_bad(pmd);
319 return 1;
320 }
321
322 return 0;
323}
324
325/* Return true if we're uffd wr-protecting file-backed memory, or false */
326static inline bool
327uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
328{
329 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
330}
331
332/*
333 * If wr-protecting the range for file-backed, populate pgtable for the case
334 * when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc()
335 * failed it means no memory, we don't have a better option but stop.
336 */
337#define change_pmd_prepare(vma, pmd, cp_flags) \
338 do { \
339 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
340 if (WARN_ON_ONCE(pte_alloc(vma->vm_mm, pmd))) \
341 break; \
342 } \
343 } while (0)
344/*
345 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
346 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
347 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
348 */
349#define change_prepare(vma, high, low, addr, cp_flags) \
350 do { \
351 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
352 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
353 if (WARN_ON_ONCE(p == NULL)) \
354 break; \
355 } \
356 } while (0)
357
358static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
359 struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
360 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
361{
362 pmd_t *pmd;
363 unsigned long next;
364 unsigned long pages = 0;
365 unsigned long nr_huge_updates = 0;
366 struct mmu_notifier_range range;
367
368 range.start = 0;
369
370 pmd = pmd_offset(pud, addr);
371 do {
372 unsigned long this_pages;
373
374 next = pmd_addr_end(addr, end);
375
376 change_pmd_prepare(vma, pmd, cp_flags);
377 /*
378 * Automatic NUMA balancing walks the tables with mmap_lock
379 * held for read. It's possible a parallel update to occur
380 * between pmd_trans_huge() and a pmd_none_or_clear_bad()
381 * check leading to a false positive and clearing.
382 * Hence, it's necessary to atomically read the PMD value
383 * for all the checks.
384 */
385 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
386 pmd_none_or_clear_bad_unless_trans_huge(pmd))
387 goto next;
388
389 /* invoke the mmu notifier if the pmd is populated */
390 if (!range.start) {
391 mmu_notifier_range_init(&range,
392 MMU_NOTIFY_PROTECTION_VMA, 0,
393 vma, vma->vm_mm, addr, end);
394 mmu_notifier_invalidate_range_start(&range);
395 }
396
397 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
398 if ((next - addr != HPAGE_PMD_SIZE) ||
399 uffd_wp_protect_file(vma, cp_flags)) {
400 __split_huge_pmd(vma, pmd, addr, false, NULL);
401 /*
402 * For file-backed, the pmd could have been
403 * cleared; make sure pmd populated if
404 * necessary, then fall-through to pte level.
405 */
406 change_pmd_prepare(vma, pmd, cp_flags);
407 } else {
408 /*
409 * change_huge_pmd() does not defer TLB flushes,
410 * so no need to propagate the tlb argument.
411 */
412 int nr_ptes = change_huge_pmd(tlb, vma, pmd,
413 addr, newprot, cp_flags);
414
415 if (nr_ptes) {
416 if (nr_ptes == HPAGE_PMD_NR) {
417 pages += HPAGE_PMD_NR;
418 nr_huge_updates++;
419 }
420
421 /* huge pmd was handled */
422 goto next;
423 }
424 }
425 /* fall through, the trans huge pmd just split */
426 }
427 this_pages = change_pte_range(tlb, vma, pmd, addr, next,
428 newprot, cp_flags);
429 pages += this_pages;
430next:
431 cond_resched();
432 } while (pmd++, addr = next, addr != end);
433
434 if (range.start)
435 mmu_notifier_invalidate_range_end(&range);
436
437 if (nr_huge_updates)
438 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
439 return pages;
440}
441
442static inline unsigned long change_pud_range(struct mmu_gather *tlb,
443 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
444 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
445{
446 pud_t *pud;
447 unsigned long next;
448 unsigned long pages = 0;
449
450 pud = pud_offset(p4d, addr);
451 do {
452 next = pud_addr_end(addr, end);
453 change_prepare(vma, pud, pmd, addr, cp_flags);
454 if (pud_none_or_clear_bad(pud))
455 continue;
456 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
457 cp_flags);
458 } while (pud++, addr = next, addr != end);
459
460 return pages;
461}
462
463static inline unsigned long change_p4d_range(struct mmu_gather *tlb,
464 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
465 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
466{
467 p4d_t *p4d;
468 unsigned long next;
469 unsigned long pages = 0;
470
471 p4d = p4d_offset(pgd, addr);
472 do {
473 next = p4d_addr_end(addr, end);
474 change_prepare(vma, p4d, pud, addr, cp_flags);
475 if (p4d_none_or_clear_bad(p4d))
476 continue;
477 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
478 cp_flags);
479 } while (p4d++, addr = next, addr != end);
480
481 return pages;
482}
483
484static unsigned long change_protection_range(struct mmu_gather *tlb,
485 struct vm_area_struct *vma, unsigned long addr,
486 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
487{
488 struct mm_struct *mm = vma->vm_mm;
489 pgd_t *pgd;
490 unsigned long next;
491 unsigned long pages = 0;
492
493 BUG_ON(addr >= end);
494 pgd = pgd_offset(mm, addr);
495 tlb_start_vma(tlb, vma);
496 do {
497 next = pgd_addr_end(addr, end);
498 change_prepare(vma, pgd, p4d, addr, cp_flags);
499 if (pgd_none_or_clear_bad(pgd))
500 continue;
501 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
502 cp_flags);
503 } while (pgd++, addr = next, addr != end);
504
505 tlb_end_vma(tlb, vma);
506
507 return pages;
508}
509
510unsigned long change_protection(struct mmu_gather *tlb,
511 struct vm_area_struct *vma, unsigned long start,
512 unsigned long end, pgprot_t newprot,
513 unsigned long cp_flags)
514{
515 unsigned long pages;
516
517 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
518
519 if (is_vm_hugetlb_page(vma))
520 pages = hugetlb_change_protection(vma, start, end, newprot,
521 cp_flags);
522 else
523 pages = change_protection_range(tlb, vma, start, end, newprot,
524 cp_flags);
525
526 return pages;
527}
528
529static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
530 unsigned long next, struct mm_walk *walk)
531{
532 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
533 0 : -EACCES;
534}
535
536static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
537 unsigned long addr, unsigned long next,
538 struct mm_walk *walk)
539{
540 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
541 0 : -EACCES;
542}
543
544static int prot_none_test(unsigned long addr, unsigned long next,
545 struct mm_walk *walk)
546{
547 return 0;
548}
549
550static const struct mm_walk_ops prot_none_walk_ops = {
551 .pte_entry = prot_none_pte_entry,
552 .hugetlb_entry = prot_none_hugetlb_entry,
553 .test_walk = prot_none_test,
554};
555
556int
557mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
558 struct vm_area_struct **pprev, unsigned long start,
559 unsigned long end, unsigned long newflags)
560{
561 struct mm_struct *mm = vma->vm_mm;
562 unsigned long oldflags = vma->vm_flags;
563 long nrpages = (end - start) >> PAGE_SHIFT;
564 unsigned int mm_cp_flags = 0;
565 unsigned long charged = 0;
566 pgoff_t pgoff;
567 int error;
568
569 if (newflags == oldflags) {
570 *pprev = vma;
571 return 0;
572 }
573
574 /*
575 * Do PROT_NONE PFN permission checks here when we can still
576 * bail out without undoing a lot of state. This is a rather
577 * uncommon case, so doesn't need to be very optimized.
578 */
579 if (arch_has_pfn_modify_check() &&
580 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
581 (newflags & VM_ACCESS_FLAGS) == 0) {
582 pgprot_t new_pgprot = vm_get_page_prot(newflags);
583
584 error = walk_page_range(current->mm, start, end,
585 &prot_none_walk_ops, &new_pgprot);
586 if (error)
587 return error;
588 }
589
590 /*
591 * If we make a private mapping writable we increase our commit;
592 * but (without finer accounting) cannot reduce our commit if we
593 * make it unwritable again. hugetlb mapping were accounted for
594 * even if read-only so there is no need to account for them here
595 */
596 if (newflags & VM_WRITE) {
597 /* Check space limits when area turns into data. */
598 if (!may_expand_vm(mm, newflags, nrpages) &&
599 may_expand_vm(mm, oldflags, nrpages))
600 return -ENOMEM;
601 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
602 VM_SHARED|VM_NORESERVE))) {
603 charged = nrpages;
604 if (security_vm_enough_memory_mm(mm, charged))
605 return -ENOMEM;
606 newflags |= VM_ACCOUNT;
607 }
608 }
609
610 /*
611 * First try to merge with previous and/or next vma.
612 */
613 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
614 *pprev = vma_merge(mm, *pprev, start, end, newflags,
615 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
616 vma->vm_userfaultfd_ctx, anon_vma_name(vma));
617 if (*pprev) {
618 vma = *pprev;
619 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
620 goto success;
621 }
622
623 *pprev = vma;
624
625 if (start != vma->vm_start) {
626 error = split_vma(mm, vma, start, 1);
627 if (error)
628 goto fail;
629 }
630
631 if (end != vma->vm_end) {
632 error = split_vma(mm, vma, end, 0);
633 if (error)
634 goto fail;
635 }
636
637success:
638 /*
639 * vm_flags and vm_page_prot are protected by the mmap_lock
640 * held in write mode.
641 */
642 vma->vm_flags = newflags;
643 if (vma_wants_manual_pte_write_upgrade(vma))
644 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
645 vma_set_page_prot(vma);
646
647 change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags);
648
649 /*
650 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
651 * fault on access.
652 */
653 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
654 (newflags & VM_WRITE)) {
655 populate_vma_page_range(vma, start, end, NULL);
656 }
657
658 vm_stat_account(mm, oldflags, -nrpages);
659 vm_stat_account(mm, newflags, nrpages);
660 perf_event_mmap(vma);
661 return 0;
662
663fail:
664 vm_unacct_memory(charged);
665 return error;
666}
667
668/*
669 * pkey==-1 when doing a legacy mprotect()
670 */
671static int do_mprotect_pkey(unsigned long start, size_t len,
672 unsigned long prot, int pkey)
673{
674 unsigned long nstart, end, tmp, reqprot;
675 struct vm_area_struct *vma, *prev;
676 int error;
677 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
678 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
679 (prot & PROT_READ);
680 struct mmu_gather tlb;
681 MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
682
683 start = untagged_addr(start);
684
685 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
686 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
687 return -EINVAL;
688
689 if (start & ~PAGE_MASK)
690 return -EINVAL;
691 if (!len)
692 return 0;
693 len = PAGE_ALIGN(len);
694 end = start + len;
695 if (end <= start)
696 return -ENOMEM;
697 if (!arch_validate_prot(prot, start))
698 return -EINVAL;
699
700 reqprot = prot;
701
702 if (mmap_write_lock_killable(current->mm))
703 return -EINTR;
704
705 /*
706 * If userspace did not allocate the pkey, do not let
707 * them use it here.
708 */
709 error = -EINVAL;
710 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
711 goto out;
712
713 mas_set(&mas, start);
714 vma = mas_find(&mas, ULONG_MAX);
715 error = -ENOMEM;
716 if (!vma)
717 goto out;
718
719 if (unlikely(grows & PROT_GROWSDOWN)) {
720 if (vma->vm_start >= end)
721 goto out;
722 start = vma->vm_start;
723 error = -EINVAL;
724 if (!(vma->vm_flags & VM_GROWSDOWN))
725 goto out;
726 } else {
727 if (vma->vm_start > start)
728 goto out;
729 if (unlikely(grows & PROT_GROWSUP)) {
730 end = vma->vm_end;
731 error = -EINVAL;
732 if (!(vma->vm_flags & VM_GROWSUP))
733 goto out;
734 }
735 }
736
737 if (start > vma->vm_start)
738 prev = vma;
739 else
740 prev = mas_prev(&mas, 0);
741
742 tlb_gather_mmu(&tlb, current->mm);
743 for (nstart = start ; ; ) {
744 unsigned long mask_off_old_flags;
745 unsigned long newflags;
746 int new_vma_pkey;
747
748 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
749
750 /* Does the application expect PROT_READ to imply PROT_EXEC */
751 if (rier && (vma->vm_flags & VM_MAYEXEC))
752 prot |= PROT_EXEC;
753
754 /*
755 * Each mprotect() call explicitly passes r/w/x permissions.
756 * If a permission is not passed to mprotect(), it must be
757 * cleared from the VMA.
758 */
759 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
760
761 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
762 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
763 newflags |= (vma->vm_flags & ~mask_off_old_flags);
764
765 /* newflags >> 4 shift VM_MAY% in place of VM_% */
766 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
767 error = -EACCES;
768 break;
769 }
770
771 /* Allow architectures to sanity-check the new flags */
772 if (!arch_validate_flags(newflags)) {
773 error = -EINVAL;
774 break;
775 }
776
777 error = security_file_mprotect(vma, reqprot, prot);
778 if (error)
779 break;
780
781 tmp = vma->vm_end;
782 if (tmp > end)
783 tmp = end;
784
785 if (vma->vm_ops && vma->vm_ops->mprotect) {
786 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
787 if (error)
788 break;
789 }
790
791 error = mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags);
792 if (error)
793 break;
794
795 nstart = tmp;
796
797 if (nstart < prev->vm_end)
798 nstart = prev->vm_end;
799 if (nstart >= end)
800 break;
801
802 vma = find_vma(current->mm, prev->vm_end);
803 if (!vma || vma->vm_start != nstart) {
804 error = -ENOMEM;
805 break;
806 }
807 prot = reqprot;
808 }
809 tlb_finish_mmu(&tlb);
810out:
811 mmap_write_unlock(current->mm);
812 return error;
813}
814
815SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
816 unsigned long, prot)
817{
818 return do_mprotect_pkey(start, len, prot, -1);
819}
820
821#ifdef CONFIG_ARCH_HAS_PKEYS
822
823SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
824 unsigned long, prot, int, pkey)
825{
826 return do_mprotect_pkey(start, len, prot, pkey);
827}
828
829SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
830{
831 int pkey;
832 int ret;
833
834 /* No flags supported yet. */
835 if (flags)
836 return -EINVAL;
837 /* check for unsupported init values */
838 if (init_val & ~PKEY_ACCESS_MASK)
839 return -EINVAL;
840
841 mmap_write_lock(current->mm);
842 pkey = mm_pkey_alloc(current->mm);
843
844 ret = -ENOSPC;
845 if (pkey == -1)
846 goto out;
847
848 ret = arch_set_user_pkey_access(current, pkey, init_val);
849 if (ret) {
850 mm_pkey_free(current->mm, pkey);
851 goto out;
852 }
853 ret = pkey;
854out:
855 mmap_write_unlock(current->mm);
856 return ret;
857}
858
859SYSCALL_DEFINE1(pkey_free, int, pkey)
860{
861 int ret;
862
863 mmap_write_lock(current->mm);
864 ret = mm_pkey_free(current->mm, pkey);
865 mmap_write_unlock(current->mm);
866
867 /*
868 * We could provide warnings or errors if any VMA still
869 * has the pkey set here.
870 */
871 return ret;
872}
873
874#endif /* CONFIG_ARCH_HAS_PKEYS */