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client-ip=162.221.158.21; receiver=esa5.hc3370-68.iphmx.com; envelope-from="sergey.dyasli@citrix.com"; x-sender="postmaster@mail.citrix.com"; x-conformance=sidf_compatible IronPort-SDR: JVR+CfOyL+tpYmHAlsitcbny7cVCDfpEkdNoxfH9qe1SlGKJAJ3g6EJhzTvj3+s9UDCFdzgiJ8 e9hfHqgfjfh1B5+nE25y09t45e/no+XXb4ywMvS6UtmNeZIUjC5WPpurjMb34uuY/HBajQUxQQ owXrGCfWMF8JUnvvRP9Idg+rXw5TtSSypLeyDkztAqTvHKuPdqD8MbhesrPTnvSWdzet2BQCUh +y2yt1ZnsMxgca7ZHKU/qdg5DrXR8O41IQG5s0fbqmPmxQeWLqGb/KcuAL6GtkLGKEqrcohKAF PO0= X-SBRS: 2.7 X-MesageID: 12479585 X-Ironport-Server: esa5.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.70,413,1574139600"; d="scan'208";a="12479585" From: Sergey Dyasli To: , , , Date: Fri, 7 Feb 2020 14:26:50 +0000 Message-ID: <20200207142652.670-3-sergey.dyasli@citrix.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200207142652.670-1-sergey.dyasli@citrix.com> References: <20200207142652.670-1-sergey.dyasli@citrix.com> MIME-Version: 1.0 Subject: [Xen-devel] [PATCH v3 2/4] x86/xen: add basic KASAN support for PV kernel X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Sergey Dyasli , Stefano Stabellini , George Dunlap , Ross Lagerwall , Alexander Potapenko , Andrey Ryabinin , Boris Ostrovsky , Andrew Morton , Dmitry Vyukov Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Introduce and use xen_kasan_* functions that are needed to properly initialise KASAN for Xen PV domains. Disable instrumentation for files that are used by xen_start_kernel() before kasan_early_init() could be called. This enables to use Outline instrumentation for Xen PV kernels. KASAN_INLINE and KASAN_VMALLOC options currently lead to boot crashes and hence disabled. Signed-off-by: Sergey Dyasli Reviewed-by: Boris Ostrovsky --- v2 --> v3: - Fix compilation without CONFIG_KASAN - Dropped _pv prefixes from new functions - Made xen_kasan_early_init() call kasan_map_early_shadow() directly - Updated description v1 --> v2: - Fix compilation without CONFIG_XEN_PV - Use macros for KASAN_SHADOW_START RFC --> v1: - New functions with declarations in xen/xen-ops.h - Fixed the issue with free_kernel_image_pages() with the help of xen_pv_kasan_unpin_pgd() --- arch/x86/mm/kasan_init_64.c | 10 ++++++++- arch/x86/xen/Makefile | 7 ++++++ arch/x86/xen/enlighten_pv.c | 3 +++ arch/x86/xen/mmu_pv.c | 43 +++++++++++++++++++++++++++++++++++++ drivers/xen/Makefile | 2 ++ include/linux/kasan.h | 2 ++ include/xen/xen-ops.h | 10 +++++++++ lib/Kconfig.kasan | 3 ++- 8 files changed, 78 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 763e71abc0fe..b862c03a2019 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -13,6 +13,8 @@ #include #include +#include + #include #include #include @@ -231,7 +233,7 @@ static void __init kasan_early_p4d_populate(pgd_t *pgd, } while (p4d++, addr = next, addr != end && p4d_none(*p4d)); } -static void __init kasan_map_early_shadow(pgd_t *pgd) +void __init kasan_map_early_shadow(pgd_t *pgd) { /* See comment in kasan_init() */ unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK; @@ -317,6 +319,8 @@ void __init kasan_early_init(void) kasan_map_early_shadow(early_top_pgt); kasan_map_early_shadow(init_top_pgt); + + xen_kasan_early_init(); } void __init kasan_init(void) @@ -348,6 +352,8 @@ void __init kasan_init(void) __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE)); } + xen_kasan_pin_pgd(early_top_pgt); + load_cr3(early_top_pgt); __flush_tlb_all(); @@ -412,6 +418,8 @@ void __init kasan_init(void) load_cr3(init_top_pgt); __flush_tlb_all(); + xen_kasan_unpin_pgd(early_top_pgt); + /* * kasan_early_shadow_page has been used as early shadow memory, thus * it may contain some garbage. Now we can clear and write protect it, diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile index 084de77a109e..102fad0b0bca 100644 --- a/arch/x86/xen/Makefile +++ b/arch/x86/xen/Makefile @@ -1,3 +1,10 @@ +KASAN_SANITIZE_enlighten_pv.o := n +KASAN_SANITIZE_enlighten.o := n +KASAN_SANITIZE_irq.o := n +KASAN_SANITIZE_mmu_pv.o := n +KASAN_SANITIZE_p2m.o := n +KASAN_SANITIZE_multicalls.o := n + # SPDX-License-Identifier: GPL-2.0 OBJECT_FILES_NON_STANDARD_xen-asm_$(BITS).o := y diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index ae4a41ca19f6..27de55699f24 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -72,6 +72,7 @@ #include #include #include +#include #ifdef CONFIG_ACPI #include @@ -1231,6 +1232,8 @@ asmlinkage __visible void __init xen_start_kernel(void) /* Get mfn list */ xen_build_dynamic_phys_to_machine(); + kasan_early_init(); + /* * Set up kernel GDT and segment registers, mainly so that * -fstack-protector code can be executed. diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index bbba8b17829a..a9a47f0bf22e 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -1771,6 +1771,41 @@ static void __init set_page_prot(void *addr, pgprot_t prot) { return set_page_prot_flags(addr, prot, UVMF_NONE); } + +#ifdef CONFIG_KASAN +void __init xen_kasan_early_init(void) +{ + if (!xen_pv_domain()) + return; + + /* PV page tables must be read-only */ + set_page_prot(kasan_early_shadow_pud, PAGE_KERNEL_RO); + set_page_prot(kasan_early_shadow_pmd, PAGE_KERNEL_RO); + set_page_prot(kasan_early_shadow_pte, PAGE_KERNEL_RO); + + /* Add KASAN mappings into initial PV page tables */ + kasan_map_early_shadow((pgd_t *)xen_start_info->pt_base); +} + +void __init xen_kasan_pin_pgd(pgd_t *pgd) +{ + if (!xen_pv_domain()) + return; + + set_page_prot(pgd, PAGE_KERNEL_RO); + pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, PFN_DOWN(__pa_symbol(pgd))); +} + +void __init xen_kasan_unpin_pgd(pgd_t *pgd) +{ + if (!xen_pv_domain()) + return; + + pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa_symbol(pgd))); + set_page_prot(pgd, PAGE_KERNEL); +} +#endif /* ifdef CONFIG_KASAN */ + #ifdef CONFIG_X86_32 static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn) { @@ -1943,6 +1978,14 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) if (i && i < pgd_index(__START_KERNEL_map)) init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i]; +#ifdef CONFIG_KASAN + /* Copy KASAN mappings */ + for (i = pgd_index(KASAN_SHADOW_START); + i < pgd_index(KASAN_SHADOW_END); + i++) + init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i]; +#endif /* ifdef CONFIG_KASAN */ + /* Make pagetable pieces RO */ set_page_prot(init_top_pgt, PAGE_KERNEL_RO); set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO); diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 0c4efa6fe450..1e9e1e41c0a8 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -1,4 +1,6 @@ # SPDX-License-Identifier: GPL-2.0 +KASAN_SANITIZE_features.o := n + obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o obj-y += grant-table.o features.o balloon.o manage.o preempt.o time.o obj-y += mem-reservation.o diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 5cde9e7c2664..2ab644229217 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -20,6 +20,8 @@ extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD]; extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD]; extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D]; +void kasan_map_early_shadow(pgd_t *pgd); + int kasan_populate_early_shadow(const void *shadow_start, const void *shadow_end); diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h index 095be1d66f31..f67f1f2d73c6 100644 --- a/include/xen/xen-ops.h +++ b/include/xen/xen-ops.h @@ -241,4 +241,14 @@ static inline void xen_preemptible_hcall_end(void) #endif /* CONFIG_PREEMPTION */ +#if defined(CONFIG_XEN_PV) && defined(CONFIG_KASAN) +void xen_kasan_early_init(void); +void xen_kasan_pin_pgd(pgd_t *pgd); +void xen_kasan_unpin_pgd(pgd_t *pgd); +#else +static inline void xen_kasan_early_init(void) { } +static inline void xen_kasan_pin_pgd(pgd_t *pgd) { } +static inline void xen_kasan_unpin_pgd(pgd_t *pgd) { } +#endif /* if defined(CONFIG_XEN_PV) && defined(CONFIG_KASAN) */ + #endif /* INCLUDE_XEN_OPS_H */ diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 81f5464ea9e1..429a638625ea 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -98,6 +98,7 @@ config KASAN_OUTLINE config KASAN_INLINE bool "Inline instrumentation" + depends on !XEN_PV help Compiler directly inserts code checking shadow memory before memory accesses. This is faster than outline (in some workloads @@ -147,7 +148,7 @@ config KASAN_SW_TAGS_IDENTIFY config KASAN_VMALLOC bool "Back mappings in vmalloc space with real shadow memory" - depends on KASAN && HAVE_ARCH_KASAN_VMALLOC + depends on KASAN && HAVE_ARCH_KASAN_VMALLOC && !XEN_PV help By default, the shadow region for vmalloc space is the read-only zero page. This means that KASAN cannot detect errors involving