From: andrey.konovalov@linux.dev To: Marco Elver <elver@google.com>, Alexander Potapenko <glider@google.com>, Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Konovalov <andreyknvl@gmail.com>, Dmitry Vyukov <dvyukov@google.com>, Andrey Ryabinin <ryabinin.a.a@gmail.com>, kasan-dev@googlegroups.com, linux-mm@kvack.org, Vincenzo Frascino <vincenzo.frascino@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, linux-arm-kernel@lists.infradead.org, Peter Collingbourne <pcc@google.com>, Evgenii Stepanov <eugenis@google.com>, linux-kernel@vger.kernel.org, Andrey Konovalov <andreyknvl@google.com> Subject: [PATCH mm v3 30/38] kasan, vmalloc: don't tag executable vmalloc allocations Date: Mon, 13 Dec 2021 22:54:26 +0100 [thread overview] Message-ID: <c77f819e87b9fefcb26c6448a027b25c939f079e.1639432170.git.andreyknvl@google.com> (raw) In-Reply-To: <cover.1639432170.git.andreyknvl@google.com> From: Andrey Konovalov <andreyknvl@google.com> The kernel can use to allocate executable memory. The only supported way to do that is via __vmalloc_node_range() with the executable bit set in the prot argument. (vmap() resets the bit via pgprot_nx()). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Don't tag the allocation if page protections allow execution. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> --- Changes v2->v3: - Add this patch. --- include/linux/kasan.h | 1 + mm/kasan/hw_tags.c | 7 +++++++ mm/kasan/shadow.c | 7 +++++++ mm/vmalloc.c | 10 +++++++--- 4 files changed, 22 insertions(+), 3 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 499f1573dba4..11f29c121bee 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -30,6 +30,7 @@ typedef unsigned int __bitwise kasan_vmalloc_flags_t; #define KASAN_VMALLOC_NONE 0x00u #define KASAN_VMALLOC_INIT 0x01u #define KASAN_VMALLOC_VM_ALLOC 0x02u +#define KASAN_VMALLOC_NOEXEC 0x04u #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index de564a6187e1..bbcf6f914490 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -246,6 +246,13 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, if (!(flags & KASAN_VMALLOC_VM_ALLOC)) return (void *)start; + /* + * Don't tag executable memory. + * The kernel doesn't tolerate having the PC register tagged. + */ + if (!(flags & KASAN_VMALLOC_NOEXEC)) + return (void *)start; + tag = kasan_random_tag(); start = set_tag(start, tag); diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index b958babc8fed..d86ab0a9dcc3 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -488,6 +488,13 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, if (!is_vmalloc_or_module_addr(start)) return (void *)start; + /* + * Don't tag executable memory. + * The kernel doesn't tolerate having the PC register tagged. + */ + if (!(flags & KASAN_VMALLOC_NOEXEC)) + return (void *)start; + start = set_tag(start, kasan_random_tag()); kasan_unpoison(start, size, false); return (void *)start; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 4171778922cc..75afd6c9bc3d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2219,7 +2219,7 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) * With hardware tag-based KASAN, marking is skipped for * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc(). */ - mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_NONE); + mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_NOEXEC); return mem; } @@ -2458,7 +2458,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, */ if (!(flags & VM_ALLOC)) area->addr = kasan_unpoison_vmalloc(area->addr, requested_size, - KASAN_VMALLOC_NONE); + KASAN_VMALLOC_NOEXEC); return area; } @@ -3133,10 +3133,14 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, * (except for the should_skip_init() check) to make sure that memory * is initialized under the same conditions regardless of the enabled * KASAN mode. + * Tag-based KASAN modes only assign tags to non-executable + * allocations, see __kasan_unpoison_vmalloc(). */ kasan_flags = KASAN_VMALLOC_VM_ALLOC; if (!want_init_on_free() && want_init_on_alloc(gfp_mask)) kasan_flags |= KASAN_VMALLOC_INIT; + if (pgprot_val(prot) == pgprot_val(pgprot_nx(prot))) + kasan_flags |= KASAN_VMALLOC_NOEXEC; addr = kasan_unpoison_vmalloc(addr, real_size, kasan_flags); /* @@ -3844,7 +3848,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, for (area = 0; area < nr_vms; area++) vms[area]->addr = kasan_unpoison_vmalloc(vms[area]->addr, vms[area]->size, - KASAN_VMALLOC_NONE); + KASAN_VMALLOC_NOEXEC); kfree(vas); return vms; -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: andrey.konovalov@linux.dev To: Marco Elver <elver@google.com>, Alexander Potapenko <glider@google.com>, Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Konovalov <andreyknvl@gmail.com>, Dmitry Vyukov <dvyukov@google.com>, Andrey Ryabinin <ryabinin.a.a@gmail.com>, kasan-dev@googlegroups.com, linux-mm@kvack.org, Vincenzo Frascino <vincenzo.frascino@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, linux-arm-kernel@lists.infradead.org, Peter Collingbourne <pcc@google.com>, Evgenii Stepanov <eugenis@google.com>, linux-kernel@vger.kernel.org, Andrey Konovalov <andreyknvl@google.com> Subject: [PATCH mm v3 30/38] kasan, vmalloc: don't tag executable vmalloc allocations Date: Mon, 13 Dec 2021 22:54:26 +0100 [thread overview] Message-ID: <c77f819e87b9fefcb26c6448a027b25c939f079e.1639432170.git.andreyknvl@google.com> (raw) In-Reply-To: <cover.1639432170.git.andreyknvl@google.com> From: Andrey Konovalov <andreyknvl@google.com> The kernel can use to allocate executable memory. The only supported way to do that is via __vmalloc_node_range() with the executable bit set in the prot argument. (vmap() resets the bit via pgprot_nx()). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Don't tag the allocation if page protections allow execution. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> --- Changes v2->v3: - Add this patch. --- include/linux/kasan.h | 1 + mm/kasan/hw_tags.c | 7 +++++++ mm/kasan/shadow.c | 7 +++++++ mm/vmalloc.c | 10 +++++++--- 4 files changed, 22 insertions(+), 3 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 499f1573dba4..11f29c121bee 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -30,6 +30,7 @@ typedef unsigned int __bitwise kasan_vmalloc_flags_t; #define KASAN_VMALLOC_NONE 0x00u #define KASAN_VMALLOC_INIT 0x01u #define KASAN_VMALLOC_VM_ALLOC 0x02u +#define KASAN_VMALLOC_NOEXEC 0x04u #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index de564a6187e1..bbcf6f914490 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -246,6 +246,13 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, if (!(flags & KASAN_VMALLOC_VM_ALLOC)) return (void *)start; + /* + * Don't tag executable memory. + * The kernel doesn't tolerate having the PC register tagged. + */ + if (!(flags & KASAN_VMALLOC_NOEXEC)) + return (void *)start; + tag = kasan_random_tag(); start = set_tag(start, tag); diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index b958babc8fed..d86ab0a9dcc3 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -488,6 +488,13 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, if (!is_vmalloc_or_module_addr(start)) return (void *)start; + /* + * Don't tag executable memory. + * The kernel doesn't tolerate having the PC register tagged. + */ + if (!(flags & KASAN_VMALLOC_NOEXEC)) + return (void *)start; + start = set_tag(start, kasan_random_tag()); kasan_unpoison(start, size, false); return (void *)start; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 4171778922cc..75afd6c9bc3d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2219,7 +2219,7 @@ void *vm_map_ram(struct page **pages, unsigned int count, int node) * With hardware tag-based KASAN, marking is skipped for * non-VM_ALLOC mappings, see __kasan_unpoison_vmalloc(). */ - mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_NONE); + mem = kasan_unpoison_vmalloc(mem, size, KASAN_VMALLOC_NOEXEC); return mem; } @@ -2458,7 +2458,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, */ if (!(flags & VM_ALLOC)) area->addr = kasan_unpoison_vmalloc(area->addr, requested_size, - KASAN_VMALLOC_NONE); + KASAN_VMALLOC_NOEXEC); return area; } @@ -3133,10 +3133,14 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, * (except for the should_skip_init() check) to make sure that memory * is initialized under the same conditions regardless of the enabled * KASAN mode. + * Tag-based KASAN modes only assign tags to non-executable + * allocations, see __kasan_unpoison_vmalloc(). */ kasan_flags = KASAN_VMALLOC_VM_ALLOC; if (!want_init_on_free() && want_init_on_alloc(gfp_mask)) kasan_flags |= KASAN_VMALLOC_INIT; + if (pgprot_val(prot) == pgprot_val(pgprot_nx(prot))) + kasan_flags |= KASAN_VMALLOC_NOEXEC; addr = kasan_unpoison_vmalloc(addr, real_size, kasan_flags); /* @@ -3844,7 +3848,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets, for (area = 0; area < nr_vms; area++) vms[area]->addr = kasan_unpoison_vmalloc(vms[area]->addr, vms[area]->size, - KASAN_VMALLOC_NONE); + KASAN_VMALLOC_NOEXEC); kfree(vas); return vms; -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-12-13 21:55 UTC|newest] Thread overview: 128+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-13 21:51 [PATCH mm v3 00/38] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 01/38] kasan, page_alloc: deduplicate should_skip_kasan_poison andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 02/38] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 03/38] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 04/38] kasan, page_alloc: simplify kasan_poison_pages call site andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-16 12:54 ` Alexander Potapenko 2021-12-16 12:54 ` Alexander Potapenko 2021-12-13 21:51 ` [PATCH mm v3 05/38] kasan, page_alloc: init memory of skipped pages on free andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 06/38] kasan: drop skip_kasan_poison variable in free_pages_prepare andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 07/38] mm: clarify __GFP_ZEROTAGS comment andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 08/38] kasan: only apply __GFP_ZEROTAGS when memory is zeroed andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:51 ` [PATCH mm v3 09/38] kasan, page_alloc: refactor init checks in post_alloc_hook andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-16 13:32 ` Alexander Potapenko 2021-12-16 13:32 ` Alexander Potapenko 2021-12-13 21:51 ` [PATCH mm v3 10/38] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook andrey.konovalov 2021-12-13 21:51 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 11/38] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-16 13:04 ` Alexander Potapenko 2021-12-16 13:04 ` Alexander Potapenko 2021-12-13 21:53 ` [PATCH mm v3 12/38] kasan, page_alloc: move SetPageSkipKASanPoison " andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 13/38] kasan, page_alloc: move kernel_init_free_pages " andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-16 11:00 ` Alexander Potapenko 2021-12-16 11:00 ` Alexander Potapenko 2021-12-13 21:53 ` [PATCH mm v3 14/38] kasan, page_alloc: simplify kasan_unpoison_pages call site andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 15/38] kasan: clean up metadata byte definitions andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-16 10:52 ` Alexander Potapenko 2021-12-16 10:52 ` Alexander Potapenko 2021-12-13 21:53 ` [PATCH mm v3 16/38] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 17/38] kasan, x86, arm64, s390: rename functions for modules shadow andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 18/38] kasan, vmalloc: drop outdated VM_KASAN comment andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-16 10:53 ` Alexander Potapenko 2021-12-16 10:53 ` Alexander Potapenko 2021-12-13 21:53 ` [PATCH mm v3 19/38] kasan: reorder vmalloc hooks andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-16 10:55 ` Alexander Potapenko 2021-12-16 10:55 ` Alexander Potapenko 2021-12-13 21:53 ` [PATCH mm v3 20/38] kasan: add wrappers for " andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:53 ` [PATCH mm v3 21/38] kasan, vmalloc: reset tags in vmalloc functions andrey.konovalov 2021-12-13 21:53 ` andrey.konovalov 2021-12-13 21:54 ` [PATCH mm v3 22/38] kasan, fork: reset pointer tags of vmapped stacks andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:54 ` [PATCH mm v3 23/38] kasan, arm64: " andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:59 ` Andrey Konovalov 2021-12-13 21:59 ` Andrey Konovalov 2021-12-14 13:25 ` Catalin Marinas 2021-12-14 13:25 ` Catalin Marinas 2021-12-13 21:54 ` [PATCH mm v3 24/38] kasan, vmalloc: add vmalloc tagging for SW_TAGS andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:54 ` [PATCH mm v3 25/38] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-14 17:11 ` Catalin Marinas 2021-12-14 17:11 ` Catalin Marinas 2021-12-14 18:27 ` Andrey Konovalov 2021-12-14 18:27 ` Andrey Konovalov 2021-12-14 19:27 ` Catalin Marinas 2021-12-14 19:27 ` Catalin Marinas 2021-12-20 21:38 ` Andrey Konovalov 2021-12-20 21:38 ` Andrey Konovalov 2021-12-13 21:54 ` [PATCH mm v3 26/38] kasan, vmalloc: don't unpoison VM_ALLOC pages before mapping andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-16 19:07 ` Alexander Potapenko 2021-12-16 19:07 ` Alexander Potapenko 2021-12-20 21:35 ` Andrey Konovalov 2021-12-20 21:35 ` Andrey Konovalov 2021-12-13 21:54 ` [PATCH mm v3 27/38] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:54 ` [PATCH mm v3 28/38] kasan, page_alloc: allow skipping memory init " andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-14 18:00 ` Marco Elver 2021-12-14 18:00 ` Marco Elver 2021-12-14 18:28 ` Andrey Konovalov 2021-12-14 18:28 ` Andrey Konovalov 2021-12-17 1:50 ` Kuan-Ying Lee 2021-12-17 1:50 ` Kuan-Ying Lee 2021-12-20 21:35 ` Andrey Konovalov 2021-12-20 21:35 ` Andrey Konovalov 2021-12-13 21:54 ` [PATCH mm v3 29/38] kasan, vmalloc: add vmalloc tagging " andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-14 19:55 ` Marco Elver 2021-12-14 19:55 ` Marco Elver 2021-12-14 22:08 ` Andrey Konovalov 2021-12-14 22:08 ` Andrey Konovalov 2021-12-14 21:03 ` Marco Elver 2021-12-14 21:03 ` Marco Elver 2021-12-13 21:54 ` andrey.konovalov [this message] 2021-12-13 21:54 ` [PATCH mm v3 30/38] kasan, vmalloc: don't tag executable vmalloc allocations andrey.konovalov 2021-12-14 19:42 ` Andrey Konovalov 2021-12-14 19:42 ` Andrey Konovalov 2021-12-13 21:54 ` [PATCH mm v3 31/38] kasan, arm64: " andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:59 ` Andrey Konovalov 2021-12-13 21:59 ` Andrey Konovalov 2021-12-17 13:45 ` Catalin Marinas 2021-12-17 13:45 ` Catalin Marinas 2021-12-13 21:54 ` [PATCH mm v3 32/38] kasan: mark kasan_arg_stacktrace as __initdata andrey.konovalov 2021-12-13 21:54 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 33/38] kasan: simplify kasan_init_hw_tags andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 34/38] kasan: add kasan.vmalloc command line flag andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 35/38] kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 36/38] arm64: select KASAN_VMALLOC for SW/HW_TAGS modes andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 37/38] kasan: documentation updates andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov 2021-12-13 21:55 ` [PATCH mm v3 38/38] kasan: improve vmalloc tests andrey.konovalov 2021-12-13 21:55 ` andrey.konovalov
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