From patchwork Mon Sep 5 12:24:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12966049 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 368F6C6FA83 for ; Mon, 5 Sep 2022 12:25:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C4A578D0079; Mon, 5 Sep 2022 08:25:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BF9328D0076; Mon, 5 Sep 2022 08:25:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A99F38D0079; Mon, 5 Sep 2022 08:25:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 9B5E08D0076 for ; Mon, 5 Sep 2022 08:25:48 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7829CC0D2A for ; Mon, 5 Sep 2022 12:25:48 +0000 (UTC) X-FDA: 79877953176.23.159C1F1 Received: from mail-ej1-f73.google.com (mail-ej1-f73.google.com [209.85.218.73]) by imf19.hostedemail.com (Postfix) with ESMTP id 20BE31A0055 for ; Mon, 5 Sep 2022 12:25:47 +0000 (UTC) Received: by mail-ej1-f73.google.com with SMTP id qf22-20020a1709077f1600b00741638c5f3cso2290886ejc.23 for ; Mon, 05 Sep 2022 05:25:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date; bh=78o9fcmZe1rakLyEcoaxPY9Q3UwZCgWFE2+savdbFCc=; b=AsRZmg4FcaRnkB2xKxGrm6iL2iDGcXmhS0tj+V1yFF2aDqOfpFXiHIRCT6zqVsW0aD N5h5Pb+5EyE1FTqgt8cLBFPdqtvKIDtXWqRbvYO/ATFWFWd2HAeTUbRSL9GKhNVVG3UR +Cz38urRZj9ZruT9hAA3LKKRoer80w2xrOai37ChA1Od6371h/dioMQgPIKGmaf+yNq2 ppD8ItTWVHSMEd1mMuPT2G7k7EIkowWAHt4nuZyfb6OsxakVTglc/JRDQZk9/I+LgGq5 2tgG5D4XNS/pj0QT5fzRb+TJYhHEDdcxlyJc0krsiHxzHfX0aka2JbETQ+vXADss1MTT Brbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=78o9fcmZe1rakLyEcoaxPY9Q3UwZCgWFE2+savdbFCc=; b=EWrURVsf1JzA6JR5V9uMVTtvY5J3EGsMXpLDe/iVWdmGfHpC6CxKY5DHp0ISgQ44n7 RcZcvsQnIET1JxuyDXU689+RM6Rhhx8MEerBWkap/H1u8OQfMXC2XYwOlDk/+herk0eH /R61f4EElQkG7KPyGJJNbuRaE/NZ90PdQX/KJjBxTRkwOQvtkmJxoqD9m1kp1oBC4XfE X0e5jwlugIle8+cfRH4mnd06XEaC9Aspm6VkbUd4OeipuG3cdp3KmpGHiD/LojbMr8d2 /RWHe5wfanvFfaRXV77JsLM6RbPoPO4QQ7LOo7FXZSBMcs1LvoblnCkGfQj6arOlyrY1 7B3Q== X-Gm-Message-State: ACgBeo1TL8q8TLPyXZQaeXnpLyPFhe0l+4BGYUWCx/734VjpEBB9Ji2G yOkGiTFWwsJ39d7UKqm9MYZTAV3z/Bg= X-Google-Smtp-Source: AA6agR6O+LsZ4k4byGii1HsmWG4VXEYNBtCLaymsFKv9VXP42ACoLM9ggDG8gs81G7Gmde8sHdwK3hc4QxA= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:b808:8d07:ab4a:554c]) (user=glider job=sendgmr) by 2002:a17:906:9bd9:b0:73d:da74:120c with SMTP id de25-20020a1709069bd900b0073dda74120cmr32752711ejc.412.1662380746896; Mon, 05 Sep 2022 05:25:46 -0700 (PDT) Date: Mon, 5 Sep 2022 14:24:26 +0200 In-Reply-To: <20220905122452.2258262-1-glider@google.com> Mime-Version: 1.0 References: <20220905122452.2258262-1-glider@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220905122452.2258262-19-glider@google.com> Subject: [PATCH v6 18/44] instrumented.h: add KMSAN support From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662380748; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=78o9fcmZe1rakLyEcoaxPY9Q3UwZCgWFE2+savdbFCc=; b=E6Mui1axoSriPN/mD7ejfYiwaq4HoNkMupU6E63mfAxRsT+BJKxY/hkQ3GR1+5EpftwvrP YBV5EeNYfMq67FvIc2nqHVb9lYT0+XkHuUSGoeubYB3BdbKTW43KWEpxMnNdTgTDXw79LY dzLZhDt+MVy3szn29KeX2t5XRIYKEu8= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=AsRZmg4F; spf=pass (imf19.hostedemail.com: domain of 3yuoVYwYKCBc38501E3BB381.zB985AHK-997Ixz7.BE3@flex--glider.bounces.google.com designates 209.85.218.73 as permitted sender) smtp.mailfrom=3yuoVYwYKCBc38501E3BB381.zB985AHK-997Ixz7.BE3@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662380748; a=rsa-sha256; cv=none; b=C2BmCsMFgWJFREAq7HJ+6MDoV6iFhSodUqxfoE/i1NWfKZ23KZ+PaKGG08BaijIbid9Y9/ 8Kw2iVH6WsD2n7MyUSL9xquYRiitK9JadLuZl42HPDJyehDVRBPgCGoSEN9e8rBI57Wclw ZSDUYTBFDGNnt2x5vYbu0w6eXHGCxGA= X-Rspam-User: X-Stat-Signature: 6h4fj5mpbeyqtgziw4gjpj5uyjhz6w9z X-Rspamd-Queue-Id: 20BE31A0055 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=AsRZmg4F; spf=pass (imf19.hostedemail.com: domain of 3yuoVYwYKCBc38501E3BB381.zB985AHK-997Ixz7.BE3@flex--glider.bounces.google.com designates 209.85.218.73 as permitted sender) smtp.mailfrom=3yuoVYwYKCBc38501E3BB381.zB985AHK-997Ixz7.BE3@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam04 X-HE-Tag: 1662380747-606307 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: To avoid false positives, KMSAN needs to unpoison the data copied from the userspace. To detect infoleaks - check the memory buffer passed to copy_to_user(). Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver --- v2: -- move implementation of kmsan_copy_to_user() here v5: -- simplify kmsan_copy_to_user() -- provide instrument_get_user() and instrument_put_user() v6: -- rebase after changing "x86: asm: instrument usercopy in get_user() and put_user()" Link: https://linux-review.googlesource.com/id/I43e93b9c02709e6be8d222342f1b044ac8bdbaaf --- include/linux/instrumented.h | 18 ++++++++++++----- include/linux/kmsan-checks.h | 19 ++++++++++++++++++ mm/kmsan/hooks.c | 38 ++++++++++++++++++++++++++++++++++++ 3 files changed, 70 insertions(+), 5 deletions(-) diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h index 9f1dba8f717b0..501fa84867494 100644 --- a/include/linux/instrumented.h +++ b/include/linux/instrumented.h @@ -2,7 +2,7 @@ /* * This header provides generic wrappers for memory access instrumentation that - * the compiler cannot emit for: KASAN, KCSAN. + * the compiler cannot emit for: KASAN, KCSAN, KMSAN. */ #ifndef _LINUX_INSTRUMENTED_H #define _LINUX_INSTRUMENTED_H @@ -10,6 +10,7 @@ #include #include #include +#include #include /** @@ -117,6 +118,7 @@ instrument_copy_to_user(void __user *to, const void *from, unsigned long n) { kasan_check_read(from, n); kcsan_check_read(from, n); + kmsan_copy_to_user(to, from, n, 0); } /** @@ -151,6 +153,7 @@ static __always_inline void instrument_copy_from_user_after(const void *to, const void __user *from, unsigned long n, unsigned long left) { + kmsan_unpoison_memory(to, n - left); } /** @@ -162,10 +165,14 @@ instrument_copy_from_user_after(const void *to, const void __user *from, * * @to destination variable, may not be address-taken */ -#define instrument_get_user(to) \ -({ \ +#define instrument_get_user(to) \ +({ \ + u64 __tmp = (u64)(to); \ + kmsan_unpoison_memory(&__tmp, sizeof(__tmp)); \ + to = __tmp; \ }) + /** * instrument_put_user() - add instrumentation to put_user()-like macros * @@ -177,8 +184,9 @@ instrument_copy_from_user_after(const void *to, const void __user *from, * @ptr userspace pointer to copy to * @size number of bytes to copy */ -#define instrument_put_user(from, ptr, size) \ -({ \ +#define instrument_put_user(from, ptr, size) \ +({ \ + kmsan_copy_to_user(ptr, &from, sizeof(from), 0); \ }) #endif /* _LINUX_INSTRUMENTED_H */ diff --git a/include/linux/kmsan-checks.h b/include/linux/kmsan-checks.h index a6522a0c28df9..c4cae333deec5 100644 --- a/include/linux/kmsan-checks.h +++ b/include/linux/kmsan-checks.h @@ -46,6 +46,21 @@ void kmsan_unpoison_memory(const void *address, size_t size); */ void kmsan_check_memory(const void *address, size_t size); +/** + * kmsan_copy_to_user() - Notify KMSAN about a data transfer to userspace. + * @to: destination address in the userspace. + * @from: source address in the kernel. + * @to_copy: number of bytes to copy. + * @left: number of bytes not copied. + * + * If this is a real userspace data transfer, KMSAN checks the bytes that were + * actually copied to ensure there was no information leak. If @to belongs to + * the kernel space (which is possible for compat syscalls), KMSAN just copies + * the metadata. + */ +void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy, + size_t left); + #else static inline void kmsan_poison_memory(const void *address, size_t size, @@ -58,6 +73,10 @@ static inline void kmsan_unpoison_memory(const void *address, size_t size) static inline void kmsan_check_memory(const void *address, size_t size) { } +static inline void kmsan_copy_to_user(void __user *to, const void *from, + size_t to_copy, size_t left) +{ +} #endif diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 6f3e64b0b61f8..5c0eb25d984d7 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -205,6 +205,44 @@ void kmsan_iounmap_page_range(unsigned long start, unsigned long end) kmsan_leave_runtime(); } +void kmsan_copy_to_user(void __user *to, const void *from, size_t to_copy, + size_t left) +{ + unsigned long ua_flags; + + if (!kmsan_enabled || kmsan_in_runtime()) + return; + /* + * At this point we've copied the memory already. It's hard to check it + * before copying, as the size of actually copied buffer is unknown. + */ + + /* copy_to_user() may copy zero bytes. No need to check. */ + if (!to_copy) + return; + /* Or maybe copy_to_user() failed to copy anything. */ + if (to_copy <= left) + return; + + ua_flags = user_access_save(); + if ((u64)to < TASK_SIZE) { + /* This is a user memory access, check it. */ + kmsan_internal_check_memory((void *)from, to_copy - left, to, + REASON_COPY_TO_USER); + } else { + /* Otherwise this is a kernel memory access. This happens when a + * compat syscall passes an argument allocated on the kernel + * stack to a real syscall. + * Don't check anything, just copy the shadow of the copied + * bytes. + */ + kmsan_internal_memmove_metadata((void *)to, (void *)from, + to_copy - left); + } + user_access_restore(ua_flags); +} +EXPORT_SYMBOL(kmsan_copy_to_user); + /* Functions from kmsan-checks.h follow. */ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags) {