diff options
Diffstat (limited to 'arch/x86/mm/pat')
| -rw-r--r-- | arch/x86/mm/pat/set_memory.c | 36 |
1 files changed, 34 insertions, 2 deletions
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 1abd5438f126..1a2d6376251c 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -580,6 +580,33 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long start, } /* + * Validate and enforce strict W^X semantics. + */ +static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long start, + unsigned long pfn, unsigned long npg) +{ + unsigned long end; + + if (!cpu_feature_enabled(X86_FEATURE_NX)) + return new; + + if (!((pgprot_val(old) ^ pgprot_val(new)) & (_PAGE_RW | _PAGE_NX))) + return new; + + if ((pgprot_val(new) & (_PAGE_RW | _PAGE_NX)) != _PAGE_RW) + return new; + + end = start + npg * PAGE_SIZE - 1; + WARN_ONCE(1, "CPA refuse W^X violation: %016llx -> %016llx range: 0x%016lx - 0x%016lx PFN %lx\n", + (unsigned long long)pgprot_val(old), + (unsigned long long)pgprot_val(new), + start, end, pfn); + + /* refuse the transition into WX */ + return old; +} + +/* * Lookup the page table entry for a virtual address in a specific pgd. * Return a pointer to the entry and the level of the mapping. */ @@ -885,6 +912,8 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address, new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages, psize, CPA_DETECT); + new_prot = verify_rwx(old_prot, new_prot, lpaddr, old_pfn, numpages); + /* * If there is a conflict, split the large page. * @@ -1525,6 +1554,7 @@ repeat: if (level == PG_LEVEL_4K) { pte_t new_pte; + pgprot_t old_prot = pte_pgprot(old_pte); pgprot_t new_prot = pte_pgprot(old_pte); unsigned long pfn = pte_pfn(old_pte); @@ -1536,6 +1566,8 @@ repeat: new_prot = static_protections(new_prot, address, pfn, 1, 0, CPA_PROTECT); + new_prot = verify_rwx(old_prot, new_prot, address, pfn, 1); + new_prot = pgprot_clear_protnone_bits(new_prot); /* @@ -1944,7 +1976,7 @@ int set_mce_nospec(unsigned long pfn) return rc; } -static int set_memory_present(unsigned long *addr, int numpages) +static int set_memory_p(unsigned long *addr, int numpages) { return change_page_attr_set(addr, numpages, __pgprot(_PAGE_PRESENT), 0); } @@ -1954,7 +1986,7 @@ int clear_mce_nospec(unsigned long pfn) { unsigned long addr = (unsigned long) pfn_to_kaddr(pfn); - return set_memory_present(&addr, 1); + return set_memory_p(&addr, 1); } EXPORT_SYMBOL_GPL(clear_mce_nospec); #endif /* CONFIG_X86_64 */ |