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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 <asm/uaccess.h>
27#include <asm/pgtable.h>
28#include <asm/cacheflush.h>
29#include <asm/tlbflush.h>
30
31#ifndef pgprot_modify
32static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33{
34 return newprot;
35}
36#endif
37
38static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable)
41{
42 pte_t *pte, oldpte;
43 spinlock_t *ptl;
44
45 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
46 arch_enter_lazy_mmu_mode();
47 do {
48 oldpte = *pte;
49 if (pte_present(oldpte)) {
50 pte_t ptent;
51
52 ptent = ptep_modify_prot_start(mm, addr, pte);
53 ptent = pte_modify(ptent, newprot);
54
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);
61
62 ptep_modify_prot_commit(mm, addr, pte, ptent);
63 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
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 }
75 }
76 } while (pte++, addr += PAGE_SIZE, addr != end);
77 arch_leave_lazy_mmu_mode();
78 pte_unmap_unlock(pte - 1, ptl);
79}
80
81static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
82 unsigned long addr, unsigned long end, pgprot_t newprot,
83 int dirty_accountable)
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_trans_huge(*pmd)) {
92 if (next - addr != HPAGE_PMD_SIZE)
93 split_huge_page_pmd(vma->vm_mm, pmd);
94 else if (change_huge_pmd(vma, pmd, addr, newprot))
95 continue;
96 /* fall through */
97 }
98 if (pmd_none_or_clear_bad(pmd))
99 continue;
100 change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
101 dirty_accountable);
102 } while (pmd++, addr = next, addr != end);
103}
104
105static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
106 unsigned long addr, unsigned long end, pgprot_t newprot,
107 int dirty_accountable)
108{
109 pud_t *pud;
110 unsigned long next;
111
112 pud = pud_offset(pgd, addr);
113 do {
114 next = pud_addr_end(addr, end);
115 if (pud_none_or_clear_bad(pud))
116 continue;
117 change_pmd_range(vma, pud, addr, next, newprot,
118 dirty_accountable);
119 } while (pud++, addr = next, addr != end);
120}
121
122static void change_protection(struct vm_area_struct *vma,
123 unsigned long addr, unsigned long end, pgprot_t newprot,
124 int dirty_accountable)
125{
126 struct mm_struct *mm = vma->vm_mm;
127 pgd_t *pgd;
128 unsigned long next;
129 unsigned long start = addr;
130
131 BUG_ON(addr >= end);
132 pgd = pgd_offset(mm, addr);
133 flush_cache_range(vma, addr, end);
134 do {
135 next = pgd_addr_end(addr, end);
136 if (pgd_none_or_clear_bad(pgd))
137 continue;
138 change_pud_range(vma, pgd, addr, next, newprot,
139 dirty_accountable);
140 } while (pgd++, addr = next, addr != end);
141 flush_tlb_range(vma, start, end);
142}
143
144int
145mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
146 unsigned long start, unsigned long end, unsigned long newflags)
147{
148 struct mm_struct *mm = vma->vm_mm;
149 unsigned long oldflags = vma->vm_flags;
150 long nrpages = (end - start) >> PAGE_SHIFT;
151 unsigned long charged = 0;
152 pgoff_t pgoff;
153 int error;
154 int dirty_accountable = 0;
155
156 if (newflags == oldflags) {
157 *pprev = vma;
158 return 0;
159 }
160
161 /*
162 * If we make a private mapping writable we increase our commit;
163 * but (without finer accounting) cannot reduce our commit if we
164 * make it unwritable again. hugetlb mapping were accounted for
165 * even if read-only so there is no need to account for them here
166 */
167 if (newflags & VM_WRITE) {
168 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
169 VM_SHARED|VM_NORESERVE))) {
170 charged = nrpages;
171 if (security_vm_enough_memory(charged))
172 return -ENOMEM;
173 newflags |= VM_ACCOUNT;
174 }
175 }
176
177 /*
178 * First try to merge with previous and/or next vma.
179 */
180 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
181 *pprev = vma_merge(mm, *pprev, start, end, newflags,
182 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
183 if (*pprev) {
184 vma = *pprev;
185 goto success;
186 }
187
188 *pprev = vma;
189
190 if (start != vma->vm_start) {
191 error = split_vma(mm, vma, start, 1);
192 if (error)
193 goto fail;
194 }
195
196 if (end != vma->vm_end) {
197 error = split_vma(mm, vma, end, 0);
198 if (error)
199 goto fail;
200 }
201
202success:
203 /*
204 * vm_flags and vm_page_prot are protected by the mmap_sem
205 * held in write mode.
206 */
207 vma->vm_flags = newflags;
208 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
209 vm_get_page_prot(newflags));
210
211 if (vma_wants_writenotify(vma)) {
212 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
213 dirty_accountable = 1;
214 }
215
216 mmu_notifier_invalidate_range_start(mm, start, end);
217 if (is_vm_hugetlb_page(vma))
218 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
219 else
220 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
221 mmu_notifier_invalidate_range_end(mm, start, end);
222 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
223 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
224 perf_event_mmap(vma);
225 return 0;
226
227fail:
228 vm_unacct_memory(charged);
229 return error;
230}
231
232SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
233 unsigned long, prot)
234{
235 unsigned long vm_flags, nstart, end, tmp, reqprot;
236 struct vm_area_struct *vma, *prev;
237 int error = -EINVAL;
238 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
239 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
240 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
241 return -EINVAL;
242
243 if (start & ~PAGE_MASK)
244 return -EINVAL;
245 if (!len)
246 return 0;
247 len = PAGE_ALIGN(len);
248 end = start + len;
249 if (end <= start)
250 return -ENOMEM;
251 if (!arch_validate_prot(prot))
252 return -EINVAL;
253
254 reqprot = prot;
255 /*
256 * Does the application expect PROT_READ to imply PROT_EXEC:
257 */
258 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
259 prot |= PROT_EXEC;
260
261 vm_flags = calc_vm_prot_bits(prot);
262
263 down_write(¤t->mm->mmap_sem);
264
265 vma = find_vma_prev(current->mm, start, &prev);
266 error = -ENOMEM;
267 if (!vma)
268 goto out;
269 if (unlikely(grows & PROT_GROWSDOWN)) {
270 if (vma->vm_start >= end)
271 goto out;
272 start = vma->vm_start;
273 error = -EINVAL;
274 if (!(vma->vm_flags & VM_GROWSDOWN))
275 goto out;
276 }
277 else {
278 if (vma->vm_start > start)
279 goto out;
280 if (unlikely(grows & PROT_GROWSUP)) {
281 end = vma->vm_end;
282 error = -EINVAL;
283 if (!(vma->vm_flags & VM_GROWSUP))
284 goto out;
285 }
286 }
287 if (start > vma->vm_start)
288 prev = vma;
289
290 for (nstart = start ; ; ) {
291 unsigned long newflags;
292
293 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
294
295 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
296
297 /* newflags >> 4 shift VM_MAY% in place of VM_% */
298 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
299 error = -EACCES;
300 goto out;
301 }
302
303 error = security_file_mprotect(vma, reqprot, prot);
304 if (error)
305 goto out;
306
307 tmp = vma->vm_end;
308 if (tmp > end)
309 tmp = end;
310 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
311 if (error)
312 goto out;
313 nstart = tmp;
314
315 if (nstart < prev->vm_end)
316 nstart = prev->vm_end;
317 if (nstart >= end)
318 goto out;
319
320 vma = prev->vm_next;
321 if (!vma || vma->vm_start != nstart) {
322 error = -ENOMEM;
323 goto out;
324 }
325 }
326out:
327 up_write(¤t->mm->mmap_sem);
328 return error;
329}
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 <uapi/linux/mman.h>
36#include <asm/cacheflush.h>
37#include <asm/mmu_context.h>
38#include <asm/tlbflush.h>
39#include <asm/tlb.h>
40
41#include "internal.h"
42
43bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
44 pte_t pte)
45{
46 struct page *page;
47
48 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
49 return false;
50
51 /* Don't touch entries that are not even readable. */
52 if (pte_protnone(pte))
53 return false;
54
55 /* Do we need write faults for softdirty tracking? */
56 if (pte_needs_soft_dirty_wp(vma, pte))
57 return false;
58
59 /* Do we need write faults for uffd-wp tracking? */
60 if (userfaultfd_pte_wp(vma, pte))
61 return false;
62
63 if (!(vma->vm_flags & VM_SHARED)) {
64 /*
65 * Writable MAP_PRIVATE mapping: We can only special-case on
66 * exclusive anonymous pages, because we know that our
67 * write-fault handler similarly would map them writable without
68 * any additional checks while holding the PT lock.
69 */
70 page = vm_normal_page(vma, addr, pte);
71 return page && PageAnon(page) && PageAnonExclusive(page);
72 }
73
74 VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
75
76 /*
77 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
78 * needs a real write-fault for writenotify
79 * (see vma_wants_writenotify()). If "dirty", the assumption is that the
80 * FS was already notified and we can simply mark the PTE writable
81 * just like the write-fault handler would do.
82 */
83 return pte_dirty(pte);
84}
85
86static long change_pte_range(struct mmu_gather *tlb,
87 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
88 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
89{
90 pte_t *pte, oldpte;
91 spinlock_t *ptl;
92 long pages = 0;
93 int target_node = NUMA_NO_NODE;
94 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
95 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
96 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
97
98 tlb_change_page_size(tlb, PAGE_SIZE);
99 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
100 if (!pte)
101 return -EAGAIN;
102
103 /* Get target node for single threaded private VMAs */
104 if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
105 atomic_read(&vma->vm_mm->mm_users) == 1)
106 target_node = numa_node_id();
107
108 flush_tlb_batched_pending(vma->vm_mm);
109 arch_enter_lazy_mmu_mode();
110 do {
111 oldpte = ptep_get(pte);
112 if (pte_present(oldpte)) {
113 pte_t ptent;
114
115 /*
116 * Avoid trapping faults against the zero or KSM
117 * pages. See similar comment in change_huge_pmd.
118 */
119 if (prot_numa) {
120 struct folio *folio;
121 int nid;
122 bool toptier;
123
124 /* Avoid TLB flush if possible */
125 if (pte_protnone(oldpte))
126 continue;
127
128 folio = vm_normal_folio(vma, addr, oldpte);
129 if (!folio || folio_is_zone_device(folio) ||
130 folio_test_ksm(folio))
131 continue;
132
133 /* Also skip shared copy-on-write pages */
134 if (is_cow_mapping(vma->vm_flags) &&
135 (folio_maybe_dma_pinned(folio) ||
136 folio_likely_mapped_shared(folio)))
137 continue;
138
139 /*
140 * While migration can move some dirty pages,
141 * it cannot move them all from MIGRATE_ASYNC
142 * context.
143 */
144 if (folio_is_file_lru(folio) &&
145 folio_test_dirty(folio))
146 continue;
147
148 /*
149 * Don't mess with PTEs if page is already on the node
150 * a single-threaded process is running on.
151 */
152 nid = folio_nid(folio);
153 if (target_node == nid)
154 continue;
155 toptier = node_is_toptier(nid);
156
157 /*
158 * Skip scanning top tier node if normal numa
159 * balancing is disabled
160 */
161 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
162 toptier)
163 continue;
164 if (folio_use_access_time(folio))
165 folio_xchg_access_time(folio,
166 jiffies_to_msecs(jiffies));
167 }
168
169 oldpte = ptep_modify_prot_start(vma, addr, pte);
170 ptent = pte_modify(oldpte, newprot);
171
172 if (uffd_wp)
173 ptent = pte_mkuffd_wp(ptent);
174 else if (uffd_wp_resolve)
175 ptent = pte_clear_uffd_wp(ptent);
176
177 /*
178 * In some writable, shared mappings, we might want
179 * to catch actual write access -- see
180 * vma_wants_writenotify().
181 *
182 * In all writable, private mappings, we have to
183 * properly handle COW.
184 *
185 * In both cases, we can sometimes still change PTEs
186 * writable and avoid the write-fault handler, for
187 * example, if a PTE is already dirty and no other
188 * COW or special handling is required.
189 */
190 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
191 !pte_write(ptent) &&
192 can_change_pte_writable(vma, addr, ptent))
193 ptent = pte_mkwrite(ptent, vma);
194
195 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
196 if (pte_needs_flush(oldpte, ptent))
197 tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
198 pages++;
199 } else if (is_swap_pte(oldpte)) {
200 swp_entry_t entry = pte_to_swp_entry(oldpte);
201 pte_t newpte;
202
203 if (is_writable_migration_entry(entry)) {
204 struct folio *folio = pfn_swap_entry_folio(entry);
205
206 /*
207 * A protection check is difficult so
208 * just be safe and disable write
209 */
210 if (folio_test_anon(folio))
211 entry = make_readable_exclusive_migration_entry(
212 swp_offset(entry));
213 else
214 entry = make_readable_migration_entry(swp_offset(entry));
215 newpte = swp_entry_to_pte(entry);
216 if (pte_swp_soft_dirty(oldpte))
217 newpte = pte_swp_mksoft_dirty(newpte);
218 } else if (is_writable_device_private_entry(entry)) {
219 /*
220 * We do not preserve soft-dirtiness. See
221 * copy_nonpresent_pte() for explanation.
222 */
223 entry = make_readable_device_private_entry(
224 swp_offset(entry));
225 newpte = swp_entry_to_pte(entry);
226 if (pte_swp_uffd_wp(oldpte))
227 newpte = pte_swp_mkuffd_wp(newpte);
228 } else if (is_writable_device_exclusive_entry(entry)) {
229 entry = make_readable_device_exclusive_entry(
230 swp_offset(entry));
231 newpte = swp_entry_to_pte(entry);
232 if (pte_swp_soft_dirty(oldpte))
233 newpte = pte_swp_mksoft_dirty(newpte);
234 if (pte_swp_uffd_wp(oldpte))
235 newpte = pte_swp_mkuffd_wp(newpte);
236 } else if (is_pte_marker_entry(entry)) {
237 /*
238 * Ignore error swap entries unconditionally,
239 * because any access should sigbus/sigsegv
240 * anyway.
241 */
242 if (is_poisoned_swp_entry(entry) ||
243 is_guard_swp_entry(entry))
244 continue;
245 /*
246 * If this is uffd-wp pte marker and we'd like
247 * to unprotect it, drop it; the next page
248 * fault will trigger without uffd trapping.
249 */
250 if (uffd_wp_resolve) {
251 pte_clear(vma->vm_mm, addr, pte);
252 pages++;
253 }
254 continue;
255 } else {
256 newpte = oldpte;
257 }
258
259 if (uffd_wp)
260 newpte = pte_swp_mkuffd_wp(newpte);
261 else if (uffd_wp_resolve)
262 newpte = pte_swp_clear_uffd_wp(newpte);
263
264 if (!pte_same(oldpte, newpte)) {
265 set_pte_at(vma->vm_mm, addr, pte, newpte);
266 pages++;
267 }
268 } else {
269 /* It must be an none page, or what else?.. */
270 WARN_ON_ONCE(!pte_none(oldpte));
271
272 /*
273 * Nobody plays with any none ptes besides
274 * userfaultfd when applying the protections.
275 */
276 if (likely(!uffd_wp))
277 continue;
278
279 if (userfaultfd_wp_use_markers(vma)) {
280 /*
281 * For file-backed mem, we need to be able to
282 * wr-protect a none pte, because even if the
283 * pte is none, the page/swap cache could
284 * exist. Doing that by install a marker.
285 */
286 set_pte_at(vma->vm_mm, addr, pte,
287 make_pte_marker(PTE_MARKER_UFFD_WP));
288 pages++;
289 }
290 }
291 } while (pte++, addr += PAGE_SIZE, addr != end);
292 arch_leave_lazy_mmu_mode();
293 pte_unmap_unlock(pte - 1, ptl);
294
295 return pages;
296}
297
298/*
299 * Return true if we want to split THPs into PTE mappings in change
300 * protection procedure, false otherwise.
301 */
302static inline bool
303pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
304{
305 /*
306 * pte markers only resides in pte level, if we need pte markers,
307 * we need to split. For example, we cannot wr-protect a file thp
308 * (e.g. 2M shmem) because file thp is handled differently when
309 * split by erasing the pmd so far.
310 */
311 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
312}
313
314/*
315 * Return true if we want to populate pgtables in change protection
316 * procedure, false otherwise
317 */
318static inline bool
319pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
320{
321 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
322 if (!(cp_flags & MM_CP_UFFD_WP))
323 return false;
324
325 /* Populate if the userfaultfd mode requires pte markers */
326 return userfaultfd_wp_use_markers(vma);
327}
328
329/*
330 * Populate the pgtable underneath for whatever reason if requested.
331 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
332 * allocation failures during page faults by kicking OOM and returning
333 * error.
334 */
335#define change_pmd_prepare(vma, pmd, cp_flags) \
336 ({ \
337 long err = 0; \
338 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
339 if (pte_alloc(vma->vm_mm, pmd)) \
340 err = -ENOMEM; \
341 } \
342 err; \
343 })
344
345/*
346 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
347 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
348 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
349 */
350#define change_prepare(vma, high, low, addr, cp_flags) \
351 ({ \
352 long err = 0; \
353 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
354 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
355 if (p == NULL) \
356 err = -ENOMEM; \
357 } \
358 err; \
359 })
360
361static inline long change_pmd_range(struct mmu_gather *tlb,
362 struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
363 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
364{
365 pmd_t *pmd;
366 unsigned long next;
367 long pages = 0;
368 unsigned long nr_huge_updates = 0;
369
370 pmd = pmd_offset(pud, addr);
371 do {
372 long ret;
373 pmd_t _pmd;
374again:
375 next = pmd_addr_end(addr, end);
376
377 ret = change_pmd_prepare(vma, pmd, cp_flags);
378 if (ret) {
379 pages = ret;
380 break;
381 }
382
383 if (pmd_none(*pmd))
384 goto next;
385
386 _pmd = pmdp_get_lockless(pmd);
387 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
388 if ((next - addr != HPAGE_PMD_SIZE) ||
389 pgtable_split_needed(vma, cp_flags)) {
390 __split_huge_pmd(vma, pmd, addr, false, NULL);
391 /*
392 * For file-backed, the pmd could have been
393 * cleared; make sure pmd populated if
394 * necessary, then fall-through to pte level.
395 */
396 ret = change_pmd_prepare(vma, pmd, cp_flags);
397 if (ret) {
398 pages = ret;
399 break;
400 }
401 } else {
402 ret = change_huge_pmd(tlb, vma, pmd,
403 addr, newprot, cp_flags);
404 if (ret) {
405 if (ret == HPAGE_PMD_NR) {
406 pages += HPAGE_PMD_NR;
407 nr_huge_updates++;
408 }
409
410 /* huge pmd was handled */
411 goto next;
412 }
413 }
414 /* fall through, the trans huge pmd just split */
415 }
416
417 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
418 cp_flags);
419 if (ret < 0)
420 goto again;
421 pages += ret;
422next:
423 cond_resched();
424 } while (pmd++, addr = next, addr != end);
425
426 if (nr_huge_updates)
427 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
428 return pages;
429}
430
431static inline long change_pud_range(struct mmu_gather *tlb,
432 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
433 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
434{
435 struct mmu_notifier_range range;
436 pud_t *pudp, pud;
437 unsigned long next;
438 long pages = 0, ret;
439
440 range.start = 0;
441
442 pudp = pud_offset(p4d, addr);
443 do {
444again:
445 next = pud_addr_end(addr, end);
446 ret = change_prepare(vma, pudp, pmd, addr, cp_flags);
447 if (ret) {
448 pages = ret;
449 break;
450 }
451
452 pud = READ_ONCE(*pudp);
453 if (pud_none(pud))
454 continue;
455
456 if (!range.start) {
457 mmu_notifier_range_init(&range,
458 MMU_NOTIFY_PROTECTION_VMA, 0,
459 vma->vm_mm, addr, end);
460 mmu_notifier_invalidate_range_start(&range);
461 }
462
463 if (pud_leaf(pud)) {
464 if ((next - addr != PUD_SIZE) ||
465 pgtable_split_needed(vma, cp_flags)) {
466 __split_huge_pud(vma, pudp, addr);
467 goto again;
468 } else {
469 ret = change_huge_pud(tlb, vma, pudp,
470 addr, newprot, cp_flags);
471 if (ret == 0)
472 goto again;
473 /* huge pud was handled */
474 if (ret == HPAGE_PUD_NR)
475 pages += HPAGE_PUD_NR;
476 continue;
477 }
478 }
479
480 pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot,
481 cp_flags);
482 } while (pudp++, addr = next, addr != end);
483
484 if (range.start)
485 mmu_notifier_invalidate_range_end(&range);
486
487 return pages;
488}
489
490static inline long change_p4d_range(struct mmu_gather *tlb,
491 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
492 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
493{
494 p4d_t *p4d;
495 unsigned long next;
496 long pages = 0, ret;
497
498 p4d = p4d_offset(pgd, addr);
499 do {
500 next = p4d_addr_end(addr, end);
501 ret = change_prepare(vma, p4d, pud, addr, cp_flags);
502 if (ret)
503 return ret;
504 if (p4d_none_or_clear_bad(p4d))
505 continue;
506 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
507 cp_flags);
508 } while (p4d++, addr = next, addr != end);
509
510 return pages;
511}
512
513static long change_protection_range(struct mmu_gather *tlb,
514 struct vm_area_struct *vma, unsigned long addr,
515 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
516{
517 struct mm_struct *mm = vma->vm_mm;
518 pgd_t *pgd;
519 unsigned long next;
520 long pages = 0, ret;
521
522 BUG_ON(addr >= end);
523 pgd = pgd_offset(mm, addr);
524 tlb_start_vma(tlb, vma);
525 do {
526 next = pgd_addr_end(addr, end);
527 ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
528 if (ret) {
529 pages = ret;
530 break;
531 }
532 if (pgd_none_or_clear_bad(pgd))
533 continue;
534 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
535 cp_flags);
536 } while (pgd++, addr = next, addr != end);
537
538 tlb_end_vma(tlb, vma);
539
540 return pages;
541}
542
543long change_protection(struct mmu_gather *tlb,
544 struct vm_area_struct *vma, unsigned long start,
545 unsigned long end, unsigned long cp_flags)
546{
547 pgprot_t newprot = vma->vm_page_prot;
548 long pages;
549
550 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
551
552#ifdef CONFIG_NUMA_BALANCING
553 /*
554 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
555 * are expected to reflect their requirements via VMA flags such that
556 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
557 */
558 if (cp_flags & MM_CP_PROT_NUMA)
559 newprot = PAGE_NONE;
560#else
561 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
562#endif
563
564 if (is_vm_hugetlb_page(vma))
565 pages = hugetlb_change_protection(vma, start, end, newprot,
566 cp_flags);
567 else
568 pages = change_protection_range(tlb, vma, start, end, newprot,
569 cp_flags);
570
571 return pages;
572}
573
574static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
575 unsigned long next, struct mm_walk *walk)
576{
577 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
578 *(pgprot_t *)(walk->private)) ?
579 0 : -EACCES;
580}
581
582static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
583 unsigned long addr, unsigned long next,
584 struct mm_walk *walk)
585{
586 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
587 *(pgprot_t *)(walk->private)) ?
588 0 : -EACCES;
589}
590
591static int prot_none_test(unsigned long addr, unsigned long next,
592 struct mm_walk *walk)
593{
594 return 0;
595}
596
597static const struct mm_walk_ops prot_none_walk_ops = {
598 .pte_entry = prot_none_pte_entry,
599 .hugetlb_entry = prot_none_hugetlb_entry,
600 .test_walk = prot_none_test,
601 .walk_lock = PGWALK_WRLOCK,
602};
603
604int
605mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
606 struct vm_area_struct *vma, struct vm_area_struct **pprev,
607 unsigned long start, unsigned long end, unsigned long newflags)
608{
609 struct mm_struct *mm = vma->vm_mm;
610 unsigned long oldflags = vma->vm_flags;
611 long nrpages = (end - start) >> PAGE_SHIFT;
612 unsigned int mm_cp_flags = 0;
613 unsigned long charged = 0;
614 int error;
615
616 if (!can_modify_vma(vma))
617 return -EPERM;
618
619 if (newflags == oldflags) {
620 *pprev = vma;
621 return 0;
622 }
623
624 /*
625 * Do PROT_NONE PFN permission checks here when we can still
626 * bail out without undoing a lot of state. This is a rather
627 * uncommon case, so doesn't need to be very optimized.
628 */
629 if (arch_has_pfn_modify_check() &&
630 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
631 (newflags & VM_ACCESS_FLAGS) == 0) {
632 pgprot_t new_pgprot = vm_get_page_prot(newflags);
633
634 error = walk_page_range(current->mm, start, end,
635 &prot_none_walk_ops, &new_pgprot);
636 if (error)
637 return error;
638 }
639
640 /*
641 * If we make a private mapping writable we increase our commit;
642 * but (without finer accounting) cannot reduce our commit if we
643 * make it unwritable again except in the anonymous case where no
644 * anon_vma has yet to be assigned.
645 *
646 * hugetlb mapping were accounted for even if read-only so there is
647 * no need to account for them here.
648 */
649 if (newflags & VM_WRITE) {
650 /* Check space limits when area turns into data. */
651 if (!may_expand_vm(mm, newflags, nrpages) &&
652 may_expand_vm(mm, oldflags, nrpages))
653 return -ENOMEM;
654 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
655 VM_SHARED|VM_NORESERVE))) {
656 charged = nrpages;
657 if (security_vm_enough_memory_mm(mm, charged))
658 return -ENOMEM;
659 newflags |= VM_ACCOUNT;
660 }
661 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) &&
662 !vma->anon_vma) {
663 newflags &= ~VM_ACCOUNT;
664 }
665
666 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags);
667 if (IS_ERR(vma)) {
668 error = PTR_ERR(vma);
669 goto fail;
670 }
671
672 *pprev = vma;
673
674 /*
675 * vm_flags and vm_page_prot are protected by the mmap_lock
676 * held in write mode.
677 */
678 vma_start_write(vma);
679 vm_flags_reset(vma, newflags);
680 if (vma_wants_manual_pte_write_upgrade(vma))
681 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
682 vma_set_page_prot(vma);
683
684 change_protection(tlb, vma, start, end, mm_cp_flags);
685
686 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT))
687 vm_unacct_memory(nrpages);
688
689 /*
690 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
691 * fault on access.
692 */
693 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
694 (newflags & VM_WRITE)) {
695 populate_vma_page_range(vma, start, end, NULL);
696 }
697
698 vm_stat_account(mm, oldflags, -nrpages);
699 vm_stat_account(mm, newflags, nrpages);
700 perf_event_mmap(vma);
701 return 0;
702
703fail:
704 vm_unacct_memory(charged);
705 return error;
706}
707
708/*
709 * pkey==-1 when doing a legacy mprotect()
710 */
711static int do_mprotect_pkey(unsigned long start, size_t len,
712 unsigned long prot, int pkey)
713{
714 unsigned long nstart, end, tmp, reqprot;
715 struct vm_area_struct *vma, *prev;
716 int error;
717 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
718 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
719 (prot & PROT_READ);
720 struct mmu_gather tlb;
721 struct vma_iterator vmi;
722
723 start = untagged_addr(start);
724
725 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
726 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
727 return -EINVAL;
728
729 if (start & ~PAGE_MASK)
730 return -EINVAL;
731 if (!len)
732 return 0;
733 len = PAGE_ALIGN(len);
734 end = start + len;
735 if (end <= start)
736 return -ENOMEM;
737 if (!arch_validate_prot(prot, start))
738 return -EINVAL;
739
740 reqprot = prot;
741
742 if (mmap_write_lock_killable(current->mm))
743 return -EINTR;
744
745 /*
746 * If userspace did not allocate the pkey, do not let
747 * them use it here.
748 */
749 error = -EINVAL;
750 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
751 goto out;
752
753 vma_iter_init(&vmi, current->mm, start);
754 vma = vma_find(&vmi, end);
755 error = -ENOMEM;
756 if (!vma)
757 goto out;
758
759 if (unlikely(grows & PROT_GROWSDOWN)) {
760 if (vma->vm_start >= end)
761 goto out;
762 start = vma->vm_start;
763 error = -EINVAL;
764 if (!(vma->vm_flags & VM_GROWSDOWN))
765 goto out;
766 } else {
767 if (vma->vm_start > start)
768 goto out;
769 if (unlikely(grows & PROT_GROWSUP)) {
770 end = vma->vm_end;
771 error = -EINVAL;
772 if (!(vma->vm_flags & VM_GROWSUP))
773 goto out;
774 }
775 }
776
777 prev = vma_prev(&vmi);
778 if (start > vma->vm_start)
779 prev = vma;
780
781 tlb_gather_mmu(&tlb, current->mm);
782 nstart = start;
783 tmp = vma->vm_start;
784 for_each_vma_range(vmi, vma, end) {
785 unsigned long mask_off_old_flags;
786 unsigned long newflags;
787 int new_vma_pkey;
788
789 if (vma->vm_start != tmp) {
790 error = -ENOMEM;
791 break;
792 }
793
794 /* Does the application expect PROT_READ to imply PROT_EXEC */
795 if (rier && (vma->vm_flags & VM_MAYEXEC))
796 prot |= PROT_EXEC;
797
798 /*
799 * Each mprotect() call explicitly passes r/w/x permissions.
800 * If a permission is not passed to mprotect(), it must be
801 * cleared from the VMA.
802 */
803 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
804
805 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
806 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
807 newflags |= (vma->vm_flags & ~mask_off_old_flags);
808
809 /* newflags >> 4 shift VM_MAY% in place of VM_% */
810 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
811 error = -EACCES;
812 break;
813 }
814
815 if (map_deny_write_exec(vma->vm_flags, newflags)) {
816 error = -EACCES;
817 break;
818 }
819
820 /* Allow architectures to sanity-check the new flags */
821 if (!arch_validate_flags(newflags)) {
822 error = -EINVAL;
823 break;
824 }
825
826 error = security_file_mprotect(vma, reqprot, prot);
827 if (error)
828 break;
829
830 tmp = vma->vm_end;
831 if (tmp > end)
832 tmp = end;
833
834 if (vma->vm_ops && vma->vm_ops->mprotect) {
835 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
836 if (error)
837 break;
838 }
839
840 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
841 if (error)
842 break;
843
844 tmp = vma_iter_end(&vmi);
845 nstart = tmp;
846 prot = reqprot;
847 }
848 tlb_finish_mmu(&tlb);
849
850 if (!error && tmp < end)
851 error = -ENOMEM;
852
853out:
854 mmap_write_unlock(current->mm);
855 return error;
856}
857
858SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
859 unsigned long, prot)
860{
861 return do_mprotect_pkey(start, len, prot, -1);
862}
863
864#ifdef CONFIG_ARCH_HAS_PKEYS
865
866SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
867 unsigned long, prot, int, pkey)
868{
869 return do_mprotect_pkey(start, len, prot, pkey);
870}
871
872SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
873{
874 int pkey;
875 int ret;
876
877 /* No flags supported yet. */
878 if (flags)
879 return -EINVAL;
880 /* check for unsupported init values */
881 if (init_val & ~PKEY_ACCESS_MASK)
882 return -EINVAL;
883
884 mmap_write_lock(current->mm);
885 pkey = mm_pkey_alloc(current->mm);
886
887 ret = -ENOSPC;
888 if (pkey == -1)
889 goto out;
890
891 ret = arch_set_user_pkey_access(current, pkey, init_val);
892 if (ret) {
893 mm_pkey_free(current->mm, pkey);
894 goto out;
895 }
896 ret = pkey;
897out:
898 mmap_write_unlock(current->mm);
899 return ret;
900}
901
902SYSCALL_DEFINE1(pkey_free, int, pkey)
903{
904 int ret;
905
906 mmap_write_lock(current->mm);
907 ret = mm_pkey_free(current->mm, pkey);
908 mmap_write_unlock(current->mm);
909
910 /*
911 * We could provide warnings or errors if any VMA still
912 * has the pkey set here.
913 */
914 return ret;
915}
916
917#endif /* CONFIG_ARCH_HAS_PKEYS */