From mboxrd@z Thu Jan 1 00:00:00 1970 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 50F4EC25B7D for ; Wed, 16 Aug 2023 21:08:10 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.a=rsa-sha256 header.s=google header.b=ZzbqonGa; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4RR1204DF3z3cTW for ; Thu, 17 Aug 2023 07:08:08 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.a=rsa-sha256 header.s=google header.b=ZzbqonGa; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=chromium.org (client-ip=2607:f8b0:4864:20::532; helo=mail-pg1-x532.google.com; envelope-from=keescook@chromium.org; receiver=lists.ozlabs.org) Received: from mail-pg1-x532.google.com (mail-pg1-x532.google.com [IPv6:2607:f8b0:4864:20::532]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4RR10y5ZYKz3cJm for ; Thu, 17 Aug 2023 07:07:13 +1000 (AEST) Received: by mail-pg1-x532.google.com with SMTP id 41be03b00d2f7-5656a5c6721so3709485a12.1 for ; Wed, 16 Aug 2023 14:07:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1692220029; x=1692824829; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=r3Yx/ofvM8SKQSiO3tHzoOQnNC0JboOEN9yZBTokARA=; b=ZzbqonGaOBv1EZxtYkwzcNc/Pza7vRjEHIfgAoe2wtMO4uUVRTZDOnNVhtsQKZGD+e Mfakd4mq9tKyJNO9S0XpGOUmbgB09a8EPzJNB5LhIeqQAA67c6KLpe5RE55XZyvNFdlA rjRwK8P6umzK3/QTZma3kszvAnRVjPePnXxkk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692220029; x=1692824829; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=r3Yx/ofvM8SKQSiO3tHzoOQnNC0JboOEN9yZBTokARA=; b=Na0LXAtXGRBQMzO3JDOnnfhr3JZTOC7TWRQZtwMpH1+XtANfCeib6A5GTWbJS/X0Qf 97tLj4061qZm51m4MyXKK4eE9DuurvamhA9BeAsAVX5TLCD2A9ZMDBftE8doZvuRiZAH 89TWgIgHV0/i+xvZueYgIr7bp014UEyeh8lOelz+CtWYbWRju/YagRatmZuWklsveq5G Tt5/KEvSSVxK6PQ0y84si30wCCaFW8CtX1rF5qbw5s9r++5zVUrySs30pyzS4aPFtQr7 XTl3EbZAEte7yamDmT8GBXYX09miNVs63F2rvYFwEpV79KZ1QA9rnDEbFthJDEmWkfBm xvTw== X-Gm-Message-State: AOJu0Yxut4afz6RWYEmqiRSfjgd7ASyRHP4Vgz5WVvVCWD+2qlGV2WJf 2UUNc/J0uVE9NFAFyC7ZH6HcJQ== X-Google-Smtp-Source: AGHT+IGtyVYYg0njIa2w4f4XfQY20e85rwgXh3WhXGv6SkwlDP1zqM0PSyoWql9zf4cbOAdyz6C0fw== X-Received: by 2002:a05:6a20:1444:b0:132:cd2d:16fd with SMTP id a4-20020a056a20144400b00132cd2d16fdmr4020731pzi.38.1692220029384; Wed, 16 Aug 2023 14:07:09 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id j20-20020aa783d4000000b00682c864f35bsm11916050pfn.140.2023.08.16.14.07.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Aug 2023 14:07:08 -0700 (PDT) Date: Wed, 16 Aug 2023 14:07:08 -0700 From: Kees Cook To: nathanl@linux.ibm.com Subject: Re: [PATCH v2] powerpc/rtas_flash: allow user copy to flash block cache objects Message-ID: <202308161407.48AAE65CB@keescook> References: <20230810-rtas-flash-vs-hardened-usercopy-v2-1-dcf63793a938@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230810-rtas-flash-vs-hardened-usercopy-v2-1-dcf63793a938@linux.ibm.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Aug 10, 2023 at 10:37:55PM -0500, Nathan Lynch via B4 Relay wrote: > From: Nathan Lynch > > With hardened usercopy enabled (CONFIG_HARDENED_USERCOPY=y), using the > /proc/powerpc/rtas/firmware_update interface to prepare a system > firmware update yields a BUG(): > > kernel BUG at mm/usercopy.c:102! > Oops: Exception in kernel mode, sig: 5 [#1] > LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries > Modules linked in: > CPU: 0 PID: 2232 Comm: dd Not tainted 6.5.0-rc3+ #2 > Hardware name: IBM,8408-E8E POWER8E (raw) 0x4b0201 0xf000004 of:IBM,FW860.50 (SV860_146) hv:phyp pSeries > NIP: c0000000005991d0 LR: c0000000005991cc CTR: 0000000000000000 > REGS: c0000000148c76a0 TRAP: 0700 Not tainted (6.5.0-rc3+) > MSR: 8000000000029033 CR: 24002242 XER: 0000000c > CFAR: c0000000001fbd34 IRQMASK: 0 > [ ... GPRs omitted ... ] > NIP [c0000000005991d0] usercopy_abort+0xa0/0xb0 > LR [c0000000005991cc] usercopy_abort+0x9c/0xb0 > Call Trace: > [c0000000148c7940] [c0000000005991cc] usercopy_abort+0x9c/0xb0 (unreliable) > [c0000000148c79b0] [c000000000536814] __check_heap_object+0x1b4/0x1d0 > [c0000000148c79f0] [c000000000599080] __check_object_size+0x2d0/0x380 > [c0000000148c7a30] [c000000000045ed4] rtas_flash_write+0xe4/0x250 > [c0000000148c7a80] [c00000000068a0fc] proc_reg_write+0xfc/0x160 > [c0000000148c7ab0] [c0000000005a381c] vfs_write+0xfc/0x4e0 > [c0000000148c7b70] [c0000000005a3e10] ksys_write+0x90/0x160 > [c0000000148c7bc0] [c00000000002f2c8] system_call_exception+0x178/0x320 > [c0000000148c7e50] [c00000000000d520] system_call_common+0x160/0x2c4 > --- interrupt: c00 at 0x7fff9f17e5e4 > > The blocks of the firmware image are copied directly from user memory > to objects allocated from flash_block_cache, so flash_block_cache must > be created using kmem_cache_create_usercopy() to mark it safe for user > access. > > Fixes: 6d07d1cd300f ("usercopy: Restrict non-usercopy caches to size 0") > Signed-off-by: Nathan Lynch Reviewed-by: Kees Cook -- Kees Cook