lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 5 Feb 2020 10:19:22 -0800 From: Yu-cheng Yu <yu-cheng.yu@...el.com> To: x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, linux-mm@...ck.org, linux-arch@...r.kernel.org, linux-api@...r.kernel.org, Arnd Bergmann <arnd@...db.de>, Andy Lutomirski <luto@...nel.org>, Balbir Singh <bsingharora@...il.com>, Borislav Petkov <bp@...en8.de>, Cyrill Gorcunov <gorcunov@...il.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Eugene Syromiatnikov <esyr@...hat.com>, Florian Weimer <fweimer@...hat.com>, "H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>, Kees Cook <keescook@...omium.org>, Mike Kravetz <mike.kravetz@...cle.com>, Nadav Amit <nadav.amit@...il.com>, Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>, Peter Zijlstra <peterz@...radead.org>, Randy Dunlap <rdunlap@...radead.org>, "Ravi V. Shankar" <ravi.v.shankar@...el.com>, Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>, Dave Martin <Dave.Martin@....com>, x86-patch-review@...el.com Cc: Yu-cheng Yu <yu-cheng.yu@...el.com> Subject: [RFC PATCH v9 14/27] mm: Handle Shadow Stack page fault When a task does fork(), its Shadow Stack (SHSTK) must be duplicated for the child. This patch implements a flow similar to copy-on-write of an anonymous page, but for SHSTK. A SHSTK PTE must be RO and Dirty. This Dirty bit requirement is used to effect the copying. In copy_one_pte(), clear the Dirty bit from a SHSTK PTE to cause a page fault upon the next SHSTK access. At that time, fix the PTE and copy/re-use the page. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com> --- arch/x86/mm/pgtable.c | 15 +++++++++++++++ include/asm-generic/pgtable.h | 17 +++++++++++++++++ mm/memory.c | 7 ++++++- 3 files changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 7bd2c3a52297..2eb33794c08d 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -872,3 +872,18 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) #endif /* CONFIG_X86_64 */ #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */ + +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER +inline bool arch_copy_pte_mapping(vm_flags_t vm_flags) +{ + return (vm_flags & VM_SHSTK); +} + +inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHSTK) + return pte_mkdirty_shstk(pte); + else + return pte; +} +#endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */ diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 798ea36a0549..9cb2f9ba5895 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -1190,6 +1190,23 @@ static inline bool arch_has_pfn_modify_check(void) } #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */ +#ifdef CONFIG_MMU +#ifndef CONFIG_ARCH_HAS_SHSTK +static inline bool arch_copy_pte_mapping(vm_flags_t vm_flags) +{ + return false; +} + +static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) +{ + return pte; +} +#else +bool arch_copy_pte_mapping(vm_flags_t vm_flags); +pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma); +#endif +#endif /* CONFIG_MMU */ + /* * Architecture PAGE_KERNEL_* fallbacks * diff --git a/mm/memory.c b/mm/memory.c index 45442d9a4f52..6daa28614327 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -772,7 +772,8 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, * If it's a COW mapping, write protect it both * in the parent and the child */ - if (is_cow_mapping(vm_flags) && pte_write(pte)) { + if ((is_cow_mapping(vm_flags) && pte_write(pte)) || + arch_copy_pte_mapping(vm_flags)) { ptep_set_wrprotect(src_mm, addr, src_pte); pte = pte_wrprotect(pte); } @@ -2417,6 +2418,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf) flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); entry = pte_mkyoung(vmf->orig_pte); entry = maybe_mkwrite(pte_mkdirty(entry), vma); + entry = pte_set_vma_features(entry, vma); if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) update_mmu_cache(vma, vmf->address, vmf->pte); pte_unmap_unlock(vmf->pte, vmf->ptl); @@ -2504,6 +2506,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); entry = mk_pte(new_page, vma->vm_page_prot); entry = maybe_mkwrite(pte_mkdirty(entry), vma); + entry = pte_set_vma_features(entry, vma); /* * Clear the pte entry and flush it first, before updating the * pte with the new entry. This will avoid a race condition @@ -3023,6 +3026,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) pte = mk_pte(page, vma->vm_page_prot); if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) { pte = maybe_mkwrite(pte_mkdirty(pte), vma); + pte = pte_set_vma_features(pte, vma); vmf->flags &= ~FAULT_FLAG_WRITE; ret |= VM_FAULT_WRITE; exclusive = RMAP_EXCLUSIVE; @@ -3165,6 +3169,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) entry = mk_pte(page, vma->vm_page_prot); if (vma->vm_flags & VM_WRITE) entry = pte_mkwrite(pte_mkdirty(entry)); + entry = pte_set_vma_features(entry, vma); vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); -- 2.21.0
Powered by blists - more mailing lists