| Message ID | 20200205181935.3712-16-yu-cheng.yu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Control-flow Enforcement: Shadow Stack | expand |
On Wed, Feb 05, 2020 at 10:19:23AM -0800, Yu-cheng Yu wrote: > This patch implements THP Shadow Stack (SHSTK) copying in the same way as > in the previous patch for regular PTE. > > In copy_huge_pmd(), clear the dirty bit from the PMD to cause a page fault > upon the next SHSTK access to the PMD. At that time, fix the PMD and > copy/re-use the page. Now is as good a time as any to ask: do you have selftests for all this? It seems like it would be really nice to have a way to verify SHSTK is working correctly. -Kees > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > --- > arch/x86/mm/pgtable.c | 8 ++++++++ > include/asm-generic/pgtable.h | 11 +++++++++++ > mm/huge_memory.c | 4 ++++ > 3 files changed, 23 insertions(+) > > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c > index 2eb33794c08d..3340b1d4e9da 100644 > --- a/arch/x86/mm/pgtable.c > +++ b/arch/x86/mm/pgtable.c > @@ -886,4 +886,12 @@ inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) > else > return pte; > } > + > +inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) > +{ > + if (vma->vm_flags & VM_SHSTK) > + return pmd_mkdirty_shstk(pmd); > + else > + return pmd; > +} > #endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */ > diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h > index 9cb2f9ba5895..a9df093fdf45 100644 > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -1201,9 +1201,20 @@ static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) > { > return pte; > } > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) > +{ > + return pmd; > +} > +#endif > #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); > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > +pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma); > +#endif > #endif > #endif /* CONFIG_MMU */ > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index a88093213674..93ef368df2dd 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -636,6 +636,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, > > entry = mk_huge_pmd(page, vma->vm_page_prot); > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); > + entry = pmd_set_vma_features(entry, vma); > page_add_new_anon_rmap(page, vma, haddr, true); > mem_cgroup_commit_charge(page, memcg, false, true); > lru_cache_add_active_or_unevictable(page, vma); > @@ -1278,6 +1279,7 @@ static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, > pte_t entry; > entry = mk_pte(pages[i], vma->vm_page_prot); > entry = maybe_mkwrite(pte_mkdirty(entry), vma); > + entry = pte_set_vma_features(entry, vma); > memcg = (void *)page_private(pages[i]); > set_page_private(pages[i], 0); > page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); > @@ -1360,6 +1362,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) > pmd_t entry; > entry = pmd_mkyoung(orig_pmd); > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); > + entry = pmd_set_vma_features(entry, vma); > if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) > update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); > ret |= VM_FAULT_WRITE; > @@ -1432,6 +1435,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) > pmd_t entry; > entry = mk_huge_pmd(new_page, vma->vm_page_prot); > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); > + entry = pmd_set_vma_features(entry, vma); > pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); > page_add_new_anon_rmap(new_page, vma, haddr, true); > mem_cgroup_commit_charge(new_page, memcg, false, true); > -- > 2.21.0 >
On Tue, 2020-02-25 at 12:59 -0800, Kees Cook wrote: > On Wed, Feb 05, 2020 at 10:19:23AM -0800, Yu-cheng Yu wrote: > > This patch implements THP Shadow Stack (SHSTK) copying in the same way as > > in the previous patch for regular PTE. > > > > In copy_huge_pmd(), clear the dirty bit from the PMD to cause a page fault > > upon the next SHSTK access to the PMD. At that time, fix the PMD and > > copy/re-use the page. > > Now is as good a time as any to ask: do you have selftests for all this? > It seems like it would be really nice to have a way to verify SHSTK is > working correctly. Yes, I have some simple tests at https://github.com/yyu168/cet-smoke-test. I also run Linux/tools/testing/selftests/x86 and GLIBC tests with CET and THP combinations. Yu-cheng
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 2eb33794c08d..3340b1d4e9da 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -886,4 +886,12 @@ inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) else return pte; } + +inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHSTK) + return pmd_mkdirty_shstk(pmd); + else + return pmd; +} #endif /* CONFIG_X86_INTEL_SHADOW_STACK_USER */ diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 9cb2f9ba5895..a9df093fdf45 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -1201,9 +1201,20 @@ static inline pte_t pte_set_vma_features(pte_t pte, struct vm_area_struct *vma) { return pte; } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma) +{ + return pmd; +} +#endif #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); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +pmd_t pmd_set_vma_features(pmd_t pmd, struct vm_area_struct *vma); +#endif #endif #endif /* CONFIG_MMU */ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index a88093213674..93ef368df2dd 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -636,6 +636,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, entry = mk_huge_pmd(page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); page_add_new_anon_rmap(page, vma, haddr, true); mem_cgroup_commit_charge(page, memcg, false, true); lru_cache_add_active_or_unevictable(page, vma); @@ -1278,6 +1279,7 @@ static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pte_t entry; entry = mk_pte(pages[i], vma->vm_page_prot); entry = maybe_mkwrite(pte_mkdirty(entry), vma); + entry = pte_set_vma_features(entry, vma); memcg = (void *)page_private(pages[i]); set_page_private(pages[i], 0); page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); @@ -1360,6 +1362,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) pmd_t entry; entry = pmd_mkyoung(orig_pmd); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); ret |= VM_FAULT_WRITE; @@ -1432,6 +1435,7 @@ vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) pmd_t entry; entry = mk_huge_pmd(new_page, vma->vm_page_prot); entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); + entry = pmd_set_vma_features(entry, vma); pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); page_add_new_anon_rmap(new_page, vma, haddr, true); mem_cgroup_commit_charge(new_page, memcg, false, true);
This patch implements THP Shadow Stack (SHSTK) copying in the same way as in the previous patch for regular PTE. In copy_huge_pmd(), clear the dirty bit from the PMD to cause a page fault upon the next SHSTK access to the PMD. At that time, fix the PMD and copy/re-use the page. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> --- arch/x86/mm/pgtable.c | 8 ++++++++ include/asm-generic/pgtable.h | 11 +++++++++++ mm/huge_memory.c | 4 ++++ 3 files changed, 23 insertions(+)