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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/pagewalk.h>#include <linux/hugetlb.h>#include <linux/shm.h>#include <linux/mman.h>#include <linux/fs.h>#include <linux/highmem.h>#include <linux/security.h>#include <linux/mempolicy.h>#include <linux/personality.h>#include <linux/syscalls.h>#include <linux/swap.h>#include <linux/swapops.h>#include <linux/mmu_notifier.h>#include <linux/migrate.h>#include <linux/perf_event.h>#include <linux/pkeys.h>#include <linux/ksm.h>#include <linux/uaccess.h>#include <linux/mm_inline.h>#include <linux/pgtable.h>#include <linux/userfaultfd_k.h>#include <uapi/linux/mman.h>#include <asm/cacheflush.h>#include <asm/mmu_context.h>#include <asm/tlbflush.h>#include <asm/tlb.h>
#include "internal.h"
static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte){ if (WARN_ON_ONCE(!vma_test(vma, VMA_WRITE_BIT))) return false;
/* Don't touch entries that are not even readable. */ if (pte_protnone(pte)) return false;
/* Do we need write faults for softdirty tracking? */ if (pte_needs_soft_dirty_wp(vma, pte)) return false;
/* Do we need write faults for uffd-wp tracking? */ if (userfaultfd_pte_wp(vma, pte)) return false;
return true;}
static bool can_change_private_pte_writable(struct vm_area_struct *vma, unsigned long addr, pte_t pte){ struct page *page;
if (!maybe_change_pte_writable(vma, pte)) return false;
/* * Writable MAP_PRIVATE mapping: We can only special-case on * exclusive anonymous pages, because we know that our * write-fault handler similarly would map them writable without * any additional checks while holding the PT lock. */ page = vm_normal_page(vma, addr, pte); return page && PageAnon(page) && PageAnonExclusive(page);}
static bool can_change_shared_pte_writable(struct vm_area_struct *vma, pte_t pte){ if (!maybe_change_pte_writable(vma, pte)) return false;
VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
/* * Writable MAP_SHARED mapping: "clean" might indicate that the FS still * needs a real write-fault for writenotify * (see vma_wants_writenotify()). If "dirty", the assumption is that the * FS was already notified and we can simply mark the PTE writable * just like the write-fault handler would do. */ return pte_dirty(pte);}
bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, pte_t pte){ if (!vma_test(vma, VMA_SHARED_BIT)) return can_change_private_pte_writable(vma, addr, pte);
return can_change_shared_pte_writable(vma, pte);}
static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep, pte_t pte, int max_nr_ptes, fpb_t flags){ /* No underlying folio, so cannot batch */ if (!folio) return 1;
if (!folio_test_large(folio)) return 1;
return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags);}
/* Set nr_ptes number of ptes, starting from idx */static __always_inline void prot_commit_flush_ptes(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, pte_t oldpte, pte_t ptent, int nr_ptes, int idx, bool set_write, struct mmu_gather *tlb){ /* * Advance the position in the batch by idx; note that if idx > 0, * then the nr_ptes passed here is <= batch size - idx. */ addr += idx * PAGE_SIZE; ptep += idx; oldpte = pte_advance_pfn(oldpte, idx); ptent = pte_advance_pfn(ptent, idx);
if (set_write) ptent = pte_mkwrite(ptent, vma);
modify_prot_commit_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes); if (pte_needs_flush(oldpte, ptent)) tlb_flush_pte_range(tlb, addr, nr_ptes * PAGE_SIZE);}
/* * Get max length of consecutive ptes pointing to PageAnonExclusive() pages or * !PageAnonExclusive() pages, starting from start_idx. Caller must enforce * that the ptes point to consecutive pages of the same anon large folio. */static __always_inline int page_anon_exclusive_batch(int start_idx, int max_len, struct page *first_page, bool expected_anon_exclusive){ int idx;
for (idx = start_idx + 1; idx < start_idx + max_len; ++idx) { if (expected_anon_exclusive != PageAnonExclusive(first_page + idx)) break; } return idx - start_idx;}
/* * This function is a result of trying our very best to retain the * "avoid the write-fault handler" optimization. In can_change_pte_writable(), * if the vma is a private vma, and we cannot determine whether to change * the pte to writable just from the vma and the pte, we then need to look * at the actual page pointed to by the pte. Unfortunately, if we have a * batch of ptes pointing to consecutive pages of the same anon large folio, * the anon-exclusivity (or the negation) of the first page does not guarantee * the anon-exclusivity (or the negation) of the other pages corresponding to * the pte batch; hence in this case it is incorrect to decide to change or * not change the ptes to writable just by using information from the first * pte of the batch. Therefore, we must individually check all pages and * retrieve sub-batches. */static __always_inline void commit_anon_folio_batch(struct vm_area_struct *vma, struct folio *folio, struct page *first_page, unsigned long addr, pte_t *ptep, pte_t oldpte, pte_t ptent, int nr_ptes, struct mmu_gather *tlb){ bool expected_anon_exclusive; int batch_idx = 0; int len;
while (nr_ptes) { expected_anon_exclusive = PageAnonExclusive(first_page + batch_idx); len = page_anon_exclusive_batch(batch_idx, nr_ptes, first_page, expected_anon_exclusive); prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, len, batch_idx, expected_anon_exclusive, tlb); batch_idx += len; nr_ptes -= len; }}
static __always_inline void set_write_prot_commit_flush_ptes(struct vm_area_struct *vma, struct folio *folio, struct page *page, unsigned long addr, pte_t *ptep, pte_t oldpte, pte_t ptent, int nr_ptes, struct mmu_gather *tlb){ bool set_write;
if (vma_test(vma, VMA_SHARED_BIT)) { set_write = can_change_shared_pte_writable(vma, ptent); prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes, /* idx = */ 0, set_write, tlb); return; }
set_write = maybe_change_pte_writable(vma, ptent) && (folio && folio_test_anon(folio)); if (!set_write) { prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes, /* idx = */ 0, set_write, tlb); return; } commit_anon_folio_batch(vma, folio, page, addr, ptep, oldpte, ptent, nr_ptes, tlb);}
static long change_softleaf_pte(struct vm_area_struct *vma, unsigned long addr, pte_t *pte, pte_t oldpte, unsigned long cp_flags){ const bool uffd_prot = cp_flags & (MM_CP_UFFD_WP | MM_CP_UFFD_RWP); const bool uffd_prot_resolve = cp_flags & (MM_CP_UFFD_WP_RESOLVE | MM_CP_UFFD_RWP_RESOLVE); softleaf_t entry = softleaf_from_pte(oldpte); pte_t newpte;
if (softleaf_is_migration_write(entry)) { const struct folio *folio = softleaf_to_folio(entry);
/* * A protection check is difficult so * just be safe and disable write */ if (folio_test_anon(folio)) entry = make_readable_exclusive_migration_entry(swp_offset(entry)); else entry = make_readable_migration_entry(swp_offset(entry)); newpte = swp_entry_to_pte(entry); if (pte_swp_soft_dirty(oldpte)) newpte = pte_swp_mksoft_dirty(newpte); } else if (softleaf_is_device_private_write(entry)) { /* * We do not preserve soft-dirtiness. See * copy_nonpresent_pte() for explanation. */ entry = make_readable_device_private_entry(swp_offset(entry)); newpte = swp_entry_to_pte(entry); if (pte_swp_uffd(oldpte)) newpte = pte_swp_mkuffd(newpte); } else if (softleaf_is_marker(entry)) { /* * Ignore error swap entries unconditionally, * because any access should sigbus/sigsegv * anyway. */ if (softleaf_is_poison_marker(entry) || softleaf_is_guard_marker(entry)) return 0; /* * If this is uffd-wp pte marker and we'd like * to unprotect it, drop it; the next page * fault will trigger without uffd trapping. */ if (uffd_prot_resolve) { pte_clear(vma->vm_mm, addr, pte); return 1; } return 0; } else { newpte = oldpte; }
if (uffd_prot) newpte = pte_swp_mkuffd(newpte); else if (uffd_prot_resolve) newpte = pte_swp_clear_uffd(newpte);
if (!pte_same(oldpte, newpte)) { set_pte_at(vma->vm_mm, addr, pte, newpte); return 1; } return 0;}
static __always_inline void change_present_ptes(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, int nr_ptes, unsigned long end, pgprot_t newprot, struct folio *folio, struct page *page, unsigned long cp_flags){ const bool uffd_prot = cp_flags & (MM_CP_UFFD_WP | MM_CP_UFFD_RWP); const bool uffd_prot_resolve = cp_flags & (MM_CP_UFFD_WP_RESOLVE | MM_CP_UFFD_RWP_RESOLVE); pte_t ptent, oldpte;
oldpte = modify_prot_start_ptes(vma, addr, ptep, nr_ptes); ptent = pte_modify(oldpte, newprot);
if (uffd_prot) ptent = pte_mkuffd(ptent); else if (uffd_prot_resolve) ptent = pte_clear_uffd(ptent);
/* * The uffd bit on a VM_UFFD_RWP VMA carries PROT_NONE * semantics. If mprotect() or NUMA hinting changed the * base protection, restore PAGE_NONE so the PTE still * traps on any access. pte_modify() preserves * _PAGE_UFFD. */ if (userfaultfd_rwp(vma) && pte_uffd(ptent)) ptent = pte_modify(ptent, PAGE_NONE);
/* * In some writable, shared mappings, we might want * to catch actual write access -- see * vma_wants_writenotify(). * * In all writable, private mappings, we have to * properly handle COW. * * In both cases, we can sometimes still change PTEs * writable and avoid the write-fault handler, for * example, if a PTE is already dirty and no other * COW or special handling is required. */ if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pte_write(ptent)) set_write_prot_commit_flush_ptes(vma, folio, page, addr, ptep, oldpte, ptent, nr_ptes, tlb); else prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes, /* idx = */ 0, /* set_write = */ false, tlb);}
static long change_pte_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags){ pte_t *pte, oldpte; spinlock_t *ptl; long pages = 0; bool is_private_single_threaded; bool prot_numa = cp_flags & MM_CP_PROT_NUMA; bool uffd_rwp = cp_flags & MM_CP_UFFD_RWP; bool uffd_wp = cp_flags & MM_CP_UFFD_WP; int nr_ptes;
tlb_change_page_size(tlb, PAGE_SIZE); pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); if (!pte) return -EAGAIN;
if (prot_numa) is_private_single_threaded = vma_is_single_threaded_private(vma);
flush_tlb_batched_pending(vma->vm_mm); lazy_mmu_mode_enable(); do { nr_ptes = 1; oldpte = ptep_get(pte); if (pte_present(oldpte)) { const fpb_t flags = FPB_RESPECT_SOFT_DIRTY | FPB_RESPECT_WRITE; int max_nr_ptes = (end - addr) >> PAGE_SHIFT; struct folio *folio = NULL; struct page *page;
/* Already in the desired state. */ if (prot_numa && pte_protnone(oldpte)) continue; /* * RWP-protected PTEs carry _PAGE_UFFD as a marker on * top of PROT_NONE. Skip only entries already in that * exact state; plain PROT_NONE from mprotect() still needs * to be promoted so future faults can be distinguished. */ if (uffd_rwp && pte_protnone(oldpte) && pte_uffd(oldpte)) continue;
page = vm_normal_page(vma, addr, oldpte); if (page) folio = page_folio(page);
/* * Avoid trapping faults against the zero or KSM * pages. See similar comment in change_huge_pmd. * Skip this filter for uffd RWP which * must set protnone regardless of NUMA placement. */ if (prot_numa && !folio_can_map_prot_numa(folio, vma, is_private_single_threaded)) {
/* determine batch to skip */ nr_ptes = mprotect_folio_pte_batch(folio, pte, oldpte, max_nr_ptes, /* flags = */ 0); continue; }
nr_ptes = mprotect_folio_pte_batch(folio, pte, oldpte, max_nr_ptes, flags);
/* * Optimize for the small-folio common case by * special-casing it here. Compiler constant propagation * plus copious amounts of __always_inline does wonders. */ if (likely(nr_ptes == 1)) { change_present_ptes(tlb, vma, addr, pte, 1, end, newprot, folio, page, cp_flags); } else { change_present_ptes(tlb, vma, addr, pte, nr_ptes, end, newprot, folio, page, cp_flags); }
pages += nr_ptes; } else if (pte_none(oldpte)) { /* * Nobody plays with any none ptes besides * userfaultfd when applying the protections. */ if (likely(!uffd_wp)) continue;
if (userfaultfd_wp_use_markers(vma)) { /* * For file-backed mem, we need to be able to * wr-protect a none pte, because even if the * pte is none, the page/swap cache could * exist. Doing that by install a marker. */ set_pte_at(vma->vm_mm, addr, pte, make_pte_marker(PTE_MARKER_UFFD_WP)); pages++; } } else { pages += change_softleaf_pte(vma, addr, pte, oldpte, cp_flags); } } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end); lazy_mmu_mode_disable(); pte_unmap_unlock(pte - 1, ptl);
return pages;}
/* * Return true if we want to split THPs into PTE mappings in change * protection procedure, false otherwise. */static inline boolpgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags){ /* * pte markers only resides in pte level, if we need pte markers, * we need to split. For example, we cannot wr-protect a file thp * (e.g. 2M shmem) because file thp is handled differently when * split by erasing the pmd so far. */ return (cp_flags & (MM_CP_UFFD_WP | MM_CP_UFFD_RWP)) && !vma_is_anonymous(vma);}
/* * Return true if we want to populate pgtables in change protection * procedure, false otherwise */static inline boolpgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags){ /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */ if (!(cp_flags & MM_CP_UFFD_WP)) return false;
/* Populate if the userfaultfd mode requires pte markers */ return userfaultfd_wp_use_markers(vma);}
/* * Populate the pgtable underneath for whatever reason if requested. * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable * allocation failures during page faults by kicking OOM and returning * error. */#define change_pmd_prepare(vma, pmd, cp_flags) \ ({ \ long err = 0; \ if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ if (pte_alloc(vma->vm_mm, pmd)) \ err = -ENOMEM; \ } \ err; \ })
/* * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. */#define change_prepare(vma, high, low, addr, cp_flags) \ ({ \ long err = 0; \ if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ if (p == NULL) \ err = -ENOMEM; \ } \ err; \ })
static inline long change_pmd_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pud_t *pud, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags){ pmd_t *pmd; unsigned long next; long pages = 0; unsigned long nr_huge_updates = 0;
pmd = pmd_offset(pud, addr); do { long ret; pmd_t _pmd;again: next = pmd_addr_end(addr, end);
ret = change_pmd_prepare(vma, pmd, cp_flags); if (ret) { pages = ret; break; }
if (pmd_none(*pmd)) goto next;
_pmd = pmdp_get_lockless(pmd); if (pmd_is_huge(_pmd)) { if ((next - addr != HPAGE_PMD_SIZE) || pgtable_split_needed(vma, cp_flags)) { __split_huge_pmd(vma, pmd, addr, false); /* * For file-backed, the pmd could have been * cleared; make sure pmd populated if * necessary, then fall-through to pte level. */ ret = change_pmd_prepare(vma, pmd, cp_flags); if (ret) { pages = ret; break; } } else { ret = change_huge_pmd(tlb, vma, pmd, addr, newprot, cp_flags); if (ret) { if (ret == HPAGE_PMD_NR) { pages += HPAGE_PMD_NR; nr_huge_updates++; }
/* huge pmd was handled */ goto next; } } /* fall through, the trans huge pmd just split */ }
ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, cp_flags); if (ret < 0) goto again; pages += ret;next: cond_resched(); } while (pmd++, addr = next, addr != end);
if (nr_huge_updates) count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); return pages;}
static inline long change_pud_range(struct mmu_gather *tlb, struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags){ struct mmu_notifier_range range; pud_t *pudp, pud; unsigned long next; long pages = 0, ret;
range.start = 0;
pudp = pud_offset(p4d, addr); do {again: next = pud_addr_end(addr, end); ret = change_prepare(vma, pudp, pmd, addr, cp_flags); if (ret) { pages = ret; break; }
pud = pudp_get(pudp); if (pud_none(pud)) continue;
if (!range.start) { mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_VMA, 0, vma->vm_mm, addr, end); mmu_notifier_invalidate_range_start(&range); }
if (pud_leaf(pud)) { if ((next - addr != PUD_SIZE) || pgtable_split_needed(vma, cp_flags)) { __split_huge_pud(vma, pudp, addr); goto again; } else { ret = change_huge_pud(tlb, vma, pudp, addr, newprot, cp_flags); if (ret == 0) goto again; /* huge pud was handled */ if (ret == HPAGE_PUD_NR) pages += HPAGE_PUD_NR; continue; } }
pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot, cp_flags); } while (pudp++, addr = next, addr != end);
if (range.start) mmu_notifier_invalidate_range_end(&range);
return pages;}
static inline long change_p4d_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags){ p4d_t *p4d; unsigned long next; long pages = 0, ret;
p4d = p4d_offset(pgd, addr); do { next = p4d_addr_end(addr, end); ret = change_prepare(vma, p4d, pud, addr, cp_flags); if (ret) return ret; if (p4d_none_or_clear_bad(p4d)) continue; pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, cp_flags); } while (p4d++, addr = next, addr != end);
return pages;}
static long change_protection_range(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags){ struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; unsigned long next; long pages = 0, ret;
BUG_ON(addr >= end); pgd = pgd_offset(mm, addr); tlb_start_vma(tlb, vma); do { next = pgd_addr_end(addr, end); ret = change_prepare(vma, pgd, p4d, addr, cp_flags); if (ret) { pages = ret; break; } if (pgd_none_or_clear_bad(pgd)) continue; pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, cp_flags); } while (pgd++, addr = next, addr != end);
tlb_end_vma(tlb, vma);
return pages;}
long change_protection(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long cp_flags){ pgprot_t newprot = vma->vm_page_prot; long pages;
/* * MM_CP_UFFD_{WP,RWP} and _RESOLVE are mutually exclusive within one * change, and WP and RWP cannot mix. Miswired callers get a warn and * a no-op; userspace cannot reach this state. */ if (WARN_ON_ONCE((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL || (cp_flags & MM_CP_UFFD_RWP_ALL) == MM_CP_UFFD_RWP_ALL || ((cp_flags & MM_CP_UFFD_WP_ALL) && (cp_flags & MM_CP_UFFD_RWP_ALL)))) return 0;
#ifdef CONFIG_NUMA_BALANCING /* * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) * are expected to reflect their requirements via VMA flags such that * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. */ if (cp_flags & MM_CP_PROT_NUMA) newprot = PAGE_NONE;#else WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);#endif
if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_PROTNONE) && (cp_flags & MM_CP_UFFD_RWP)) newprot = PAGE_NONE;
if (vma_is_hugetlb(vma)) pages = hugetlb_change_protection(vma, start, end, newprot, cp_flags); else pages = change_protection_range(tlb, vma, start, end, newprot, cp_flags);
return pages;}
static int prot_none_pte_entry(pte_t *pte, unsigned long addr, unsigned long next, struct mm_walk *walk){ return pfn_modify_allowed(pte_pfn(ptep_get(pte)), *(pgprot_t *)(walk->private)) ? 0 : -EACCES;}
#ifdef CONFIG_HUGETLB_PAGEstatic int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, unsigned long addr, unsigned long next, struct mm_walk *walk){ const pte_t entry = huge_ptep_get(walk->mm, addr, pte);
if (pfn_modify_allowed(pte_pfn(entry), *(pgprot_t *)(walk->private))) return 0; return -EACCES;}#else#define prot_none_hugetlb_entry NULL#endif
static const struct mm_walk_ops prot_none_walk_ops = { .pte_entry = prot_none_pte_entry, .hugetlb_entry = prot_none_hugetlb_entry, .walk_lock = PGWALK_WRLOCK,};
intmprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, struct vm_area_struct *vma, struct vm_area_struct **pprev, unsigned long start, unsigned long end, vm_flags_t newflags){ struct mm_struct *mm = vma->vm_mm; const vma_flags_t old_vma_flags = READ_ONCE(vma->flags); vma_flags_t new_vma_flags = legacy_to_vma_flags(newflags); long nrpages = (end - start) >> PAGE_SHIFT; unsigned int mm_cp_flags = 0; unsigned long charged = 0; int error;
if (vma_is_sealed(vma)) return -EPERM;
if (vma_flags_same_pair(&old_vma_flags, &new_vma_flags)) { *pprev = vma; return 0; }
/* * Do PROT_NONE PFN permission checks here when we can still * bail out without undoing a lot of state. This is a rather * uncommon case, so doesn't need to be very optimized. */ if (arch_has_pfn_modify_check() && !vma_flags_is_mm_managed(&old_vma_flags) && !vma_flags_test_any_mask(&new_vma_flags, VMA_ACCESS_FLAGS)) { pgprot_t new_pgprot = vm_get_page_prot(newflags);
error = walk_page_range_vma(vma, start, end, &prot_none_walk_ops, &new_pgprot); if (error) return error; }
/* * If we make a private mapping writable we increase our commit; * but (without finer accounting) cannot reduce our commit if we * make it unwritable again except in the anonymous case where the * VMA's anon rmap has yet to be assigned. * * hugetlb mapping were accounted for even if read-only so there is * no need to account for them here. */ if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT)) { /* Check space limits when area turns into data. */ if (!may_expand_vm(mm, &new_vma_flags, nrpages) && may_expand_vm(mm, &old_vma_flags, nrpages)) return -ENOMEM; if (!vma_flags_test_any(&old_vma_flags, VMA_ACCOUNT_BIT, VMA_WRITE_BIT, VMA_HUGETLB_BIT, VMA_SHARED_BIT, VMA_NORESERVE_BIT)) { charged = nrpages; if (security_vm_enough_memory_mm(mm, charged)) return -ENOMEM; vma_flags_set(&new_vma_flags, VMA_ACCOUNT_BIT); } } else if (vma_flags_test(&old_vma_flags, VMA_ACCOUNT_BIT) && vma_is_anonymous(vma) && !vma_has_anon_rmap(vma)) { vma_flags_clear(&new_vma_flags, VMA_ACCOUNT_BIT); }
vma = vma_modify_flags(vmi, *pprev, vma, start, end, &new_vma_flags); if (IS_ERR(vma)) { error = PTR_ERR(vma); goto fail; }
*pprev = vma;
/* * vm_flags and vm_page_prot are protected by the mmap_lock * held in write mode. */ vma_start_write(vma); vma_flags_reset_once(vma, &new_vma_flags); if (vma_wants_manual_pte_write_upgrade(vma)) mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; vma_set_page_prot(vma);
change_protection(tlb, vma, start, end, mm_cp_flags);
if (vma_flags_test(&old_vma_flags, VMA_ACCOUNT_BIT) && !vma_flags_test(&new_vma_flags, VMA_ACCOUNT_BIT)) vm_unacct_memory(nrpages);
/* * Private VMA_LOCKED_BIT VMA becoming writable: trigger COW to avoid * major fault on access. */ if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT) && vma_flags_test(&old_vma_flags, VMA_LOCKED_BIT) && !vma_flags_test_any(&old_vma_flags, VMA_WRITE_BIT, VMA_SHARED_BIT)) populate_vma_page_range(vma, start, end, NULL);
vm_stat_account(mm, vma_flags_to_legacy(old_vma_flags), -nrpages); newflags = vma_flags_to_legacy(new_vma_flags); vm_stat_account(mm, newflags, nrpages); perf_event_mmap(vma); return 0;
fail: vm_unacct_memory(charged); return error;}
/* * pkey==-1 when doing a legacy mprotect() */static int do_mprotect_pkey(unsigned long start, size_t len, unsigned long prot, int pkey){ unsigned long nstart, end, tmp, reqprot; struct vm_area_struct *vma, *prev; int error; const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); const bool rier = (current->personality & READ_IMPLIES_EXEC) && (prot & PROT_READ); struct mmu_gather tlb; struct vma_iterator vmi;
start = untagged_addr(start);
prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ return -EINVAL;
if (start & ~PAGE_MASK) return -EINVAL; if (!len) return 0; len = PAGE_ALIGN(len); end = start + len; if (end <= start) return -ENOMEM; if (!arch_validate_prot(prot, start)) return -EINVAL;
reqprot = prot;
if (mmap_write_lock_killable(current->mm)) return -EINTR;
/* * If userspace did not allocate the pkey, do not let * them use it here. */ error = -EINVAL; if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) goto out;
vma_iter_init(&vmi, current->mm, start); vma = vma_find(&vmi, end); error = -ENOMEM; if (!vma) goto out;
if (unlikely(grows & PROT_GROWSDOWN)) { if (vma->vm_start >= end) goto out; start = vma->vm_start; error = -EINVAL; if (!vma_test(vma, VMA_GROWSDOWN_BIT)) goto out; } else { if (vma->vm_start > start) goto out; if (unlikely(grows & PROT_GROWSUP)) { end = vma->vm_end; error = -EINVAL; if (!vma_test_single_mask(vma, VMA_GROWSUP)) goto out; } }
prev = vma_prev(&vmi); if (start > vma->vm_start) prev = vma;
tlb_gather_mmu(&tlb, current->mm); nstart = start; tmp = vma->vm_start; for_each_vma_range(vmi, vma, end) { vm_flags_t mask_off_old_flags; vma_flags_t new_vma_flags; vm_flags_t newflags; int new_vma_pkey;
if (vma->vm_start != tmp) { error = -ENOMEM; break; }
/* Does the application expect PROT_READ to imply PROT_EXEC */ if (rier && vma_test(vma, VMA_MAYEXEC_BIT)) prot |= PROT_EXEC;
/* * Each mprotect() call explicitly passes r/w/x permissions. * If a permission is not passed to mprotect(), it must be * cleared from the VMA. */ mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); newflags = calc_vm_prot_bits(prot, new_vma_pkey); newflags |= (vma->vm_flags & ~mask_off_old_flags); new_vma_flags = legacy_to_vma_flags(newflags);
/* newflags >> 4 shift VM_MAY% in place of VM_% */ if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { error = -EACCES; break; }
if (map_deny_write_exec(&vma->flags, &new_vma_flags)) { error = -EACCES; break; }
/* Allow architectures to sanity-check the new flags */ if (!arch_validate_flags(newflags)) { error = -EINVAL; break; }
error = security_file_mprotect(vma, reqprot, prot); if (error) break;
tmp = vma->vm_end; if (tmp > end) tmp = end;
if (vma->vm_ops && vma->vm_ops->mprotect) { error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); if (error) break; }
error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); if (error) break;
tmp = vma_iter_end(&vmi); nstart = tmp; prot = reqprot; } tlb_finish_mmu(&tlb);
if (!error && tmp < end) error = -ENOMEM;
out: mmap_write_unlock(current->mm); return error;}
SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, unsigned long, prot){ return do_mprotect_pkey(start, len, prot, -1);}
#ifdef CONFIG_ARCH_HAS_PKEYS
SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, unsigned long, prot, int, pkey){ return do_mprotect_pkey(start, len, prot, pkey);}
SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val){ int pkey; int ret;
/* No flags supported yet. */ if (flags) return -EINVAL; /* check for unsupported init values */ if (init_val & ~PKEY_ACCESS_MASK) return -EINVAL;
mmap_write_lock(current->mm); pkey = mm_pkey_alloc(current->mm);
ret = -ENOSPC; if (pkey == -1) goto out;
ret = arch_set_user_pkey_access(pkey, init_val); if (ret) { mm_pkey_free(current->mm, pkey); goto out; } ret = pkey;out: mmap_write_unlock(current->mm); return ret;}
SYSCALL_DEFINE1(pkey_free, int, pkey){ int ret;
mmap_write_lock(current->mm); ret = mm_pkey_free(current->mm, pkey); mmap_write_unlock(current->mm);
/* * We could provide warnings or errors if any VMA still * has the pkey set here. */ return ret;}
#endif /* CONFIG_ARCH_HAS_PKEYS */