From patchwork Fri Sep 29 03:24:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 146405 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:cae8:0:b0:403:3b70:6f57 with SMTP id r8csp3754125vqu; Thu, 28 Sep 2023 20:25:52 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEe7Bptmk8uReIIeN0jy2xwuZUiHEgfsjAyrTip0rIl32Er3GC1o8ZGi0FzYpsOOXNHT40F X-Received: by 2002:a17:903:110e:b0:1c6:117b:7086 with SMTP id n14-20020a170903110e00b001c6117b7086mr3492713plh.5.1695957951965; Thu, 28 Sep 2023 20:25:51 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1695957951; cv=none; d=google.com; s=arc-20160816; b=XGS0DfR/nEdt9dAGky6xgZtjl3uwLp96sE7qaRua/Ekj3c5M1pV2DcAUtfoEfrOMws UcuU95eKC/hMJGNcZD/clJtVUv4R9Nmex9xK4j8NKTiLtdWRnGd4Y94ezehXIQHlwOwK DN+fUCZvEKsSKxuywYIvxlRTd2r64mwLIGBrRxs77hcWRbK7EBeiGMnRDZnASYFeW3E6 CIkRYsOy99v+VjWZ1anRp12Tjt3sl/dhCxgLKpkV7TpQRVm+h67fs7aqCLqBRIFyptVx WgeEPW/t683TbJiAGafYZ+koHCongQ3znGOLbr3/56/ah8pw9Ib5pqY0XtrWyb7g4roR HVKg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=1N2/5RenlXFMtuBqo/+f8Vcn16/Uj2Iw7MwFuqiNorY=; fh=uM8fZIJrIH8hFNh2+0CTuXQ2rc4vyoNeB2hYGvjxI3M=; b=wEyyJBlrO8ZY5xxPY8rRR8W04wDFbGFrCWbSJQMmrJtdkx6vbbWDzLZfdsXLUjqL38 gMv2PgNOTk5pXWiywFEbxr0vZrXMHZRq1bZpdq/PO4cizJOIMlepOs1mnK4ymTVfxVSN LGBI8u38eeZU1RFYK0k0mJcjff1QCz2rAlNafE5GSh3ujleMwq/fOIB/vZ38MPuLe/K0 odkD8r3qeP4BmQfNCFRYRjr2Xh1v1e32G7K5A+zfhuPQbSCmFDoY2NHlyYPymsGdGcJA wbZMIII4V5Ubxl4giKX532XBKgrSpbfP0Zmx1xp3jYRhfnxcg8nGUjKzFLsbgXEw0HWt AP9Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=gHYyAdOo; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from morse.vger.email (morse.vger.email. [2620:137:e000::3:1]) by mx.google.com with ESMTPS id j4-20020a170903028400b001c5c370d4d3si20965372plr.534.2023.09.28.20.25.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Sep 2023 20:25:51 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) client-ip=2620:137:e000::3:1; Authentication-Results: mx.google.com; dkim=pass header.i=@chromium.org header.s=google header.b=gHYyAdOo; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chromium.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id 5F5BC82C7B5A; Thu, 28 Sep 2023 20:25:37 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232694AbjI2DZO (ORCPT + 20 others); Thu, 28 Sep 2023 23:25:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232600AbjI2DYv (ORCPT ); Thu, 28 Sep 2023 23:24:51 -0400 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EC3B1B1 for ; Thu, 28 Sep 2023 20:24:43 -0700 (PDT) Received: by mail-pg1-x530.google.com with SMTP id 41be03b00d2f7-517ab9a4a13so9931669a12.1 for ; Thu, 28 Sep 2023 20:24:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1695957882; x=1696562682; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=1N2/5RenlXFMtuBqo/+f8Vcn16/Uj2Iw7MwFuqiNorY=; b=gHYyAdOoo9+Uq0fM+3FDoaZjk+aghJ6WPsGkXPszGftW8VjFFXzy5d93L9aLeFwAyd ni2RloEREBWicKL8qFOb2QZyUIzcTVsLW+9zzyU9fq5euZ9xVNh3PaRWTcV5nw//82Pq yL9rgN+tzJFgm0KSeoLGYfnpud/KR5kuELKag= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695957882; x=1696562682; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1N2/5RenlXFMtuBqo/+f8Vcn16/Uj2Iw7MwFuqiNorY=; b=nQygZyECE3sL9zFDdJ3Ot4Ylx6NshH/pWfsbXzrVmx8X601p8oCVDZrMWFDoWhh3bl IubMA5t9hXdH6hTmb6Xk6waYdxemYdXAs2xnZODXN2kKcgVGg3Qyd337cwrWzRnXSVid puxheqdd3qADMQvZhQsEyCiUb+7gB4JCK4+NpijoiWNxmiaqKpRw2o0ooPkEVaDiuOR6 kMgnoicIP3dO+Oun0eYCPC8TGAHaaVIJMiXoXQmFkBj5GktDvHxggMhqUhd9oUMYGO8T tftLaFpzhcZFNo+OSlaJ5aAzyjhoF3j9UC6a7x483DMwftcNBTmOaw30ZXRm3pCzsPp+ yBAw== X-Gm-Message-State: AOJu0Yzl6mM/7LvCPHgQzZbvBCWdtk9Gg4YA7DOpWTNESPL1DHMMAAm6 9H56atSaXZ7Ia+/5Uu0TW9xzoQ== X-Received: by 2002:a05:6a21:6d90:b0:162:d056:9f52 with SMTP id wl16-20020a056a216d9000b00162d0569f52mr2317143pzb.14.1695957882509; Thu, 28 Sep 2023 20:24:42 -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 d12-20020a17090a498c00b0026b3ed37ddcsm297774pjh.32.2023.09.28.20.24.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 Sep 2023 20:24:39 -0700 (PDT) From: Kees Cook To: Eric Biederman Cc: Kees Cook , Alexander Viro , Christian Brauner , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Sebastian Ott , =?utf-8?q?Thomas_Wei?= =?utf-8?q?=C3=9Fschuh?= , Pedro Falcato , Andrew Morton , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v4 5/6] binfmt_elf: Only report padzero() errors when PROT_WRITE Date: Thu, 28 Sep 2023 20:24:33 -0700 Message-Id: <20230929032435.2391507-5-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230929031716.it.155-kees@kernel.org> References: <20230929031716.it.155-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3206; i=keescook@chromium.org; h=from:subject; bh=jt1fmczJcOormxbVcL/G+gA6YgAS2bIpzH9lxZKP6J8=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlFkNyRwIKy/9+p28ZJ729vcNHK8Gg7yPfE0ByN 6nvj7/qVLeJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZRZDcgAKCRCJcvTf3G3A JjvTD/0efjaJu1+PNkM8NRGdk1dsGyZJ0dd4tY+8HW5FWR8J7niOASg788NVSLqFFUmdhaHRjmO Lj56b26Bw9GOyQXHYda5l7wqDTMXm6RIMUYBjTHTuUu3K8IYicpe/vidGvDuun74TWC6gT0TcQS JBtpkVYUzN9Quzlr+hjKY4YwSAMa+50O1SYTdUGqwmckLYkIpbbwVLAo7r/VX4KL73ojipa0uZL U4Z96HcimN4eOgUTJL+Z0t4VxznrtCujhN04154vNUcC1vzmWqEyPkrIaegDJh86UloTxqH/Esa mEVSbpK9HjAWKRRsvhfOPp2btfPm3150XfvwHXXipw4qVDOWOWYhb7tHCVoYriEG/H0nn5qroT1 PIRndidx60sCNBiIR++8QGxeZhVypD2rtBlFMJYxk8hREnuCOUIUakD1s4SmYoqYAa/N6j10yfn USW7wazw7KE0x/SHGyklD7+FJFIHi/dFaGRXo6PdpXd2O8m/Fnh82Px9LxMZldJtVxrwmm2YcUb AIegTgqbd3pR1GCUvhncdf3yEUBwywr6llI4pfc2Bpc4oznxAVKNeJoY5hIrwCbXVKuO54wkBIg dP9Sl+hc6k26DlLVynWraFAeBWkU+QBlgtEZI18h+WBXWKlb9zkdhbKOcrAovas3JG4CcT3Onsb u68NsqyzQBTv3nw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Thu, 28 Sep 2023 20:25:37 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1778340805275055700 X-GMAIL-MSGID: 1778340805275055700 Errors with padzero() should be caught unless we're expecting a pathological (non-writable) segment. Report -EFAULT only when PROT_WRITE is present. Additionally add some more documentation to padzero(), elf_map(), and elf_load(). Cc: Eric Biederman Cc: Alexander Viro Cc: Christian Brauner Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Suggested-by: Eric Biederman Signed-off-by: Kees Cook --- fs/binfmt_elf.c | 32 +++++++++++++++++++++++--------- 1 file changed, 23 insertions(+), 9 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index f8b4747f87ed..22027b0a5923 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -110,19 +110,19 @@ static struct linux_binfmt elf_format = { #define BAD_ADDR(x) (unlikely((unsigned long)(x) >= TASK_SIZE)) -/* We need to explicitly zero any fractional pages - after the data section (i.e. bss). This would - contain the junk from the file that should not - be in memory +/* + * We need to explicitly zero any trailing portion of the page that follows + * p_filesz when it ends before the page ends (e.g. bss), otherwise this + * memory will contain the junk from the file that should not be present. */ -static int padzero(unsigned long elf_bss) +static int padzero(unsigned long address) { unsigned long nbyte; - nbyte = ELF_PAGEOFFSET(elf_bss); + nbyte = ELF_PAGEOFFSET(address); if (nbyte) { nbyte = ELF_MIN_ALIGN - nbyte; - if (clear_user((void __user *) elf_bss, nbyte)) + if (clear_user((void __user *)address, nbyte)) return -EFAULT; } return 0; @@ -348,6 +348,11 @@ create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec, return 0; } +/* + * Map "eppnt->p_filesz" bytes from "filep" offset "eppnt->p_offset" + * into memory at "addr". (Note that p_filesz is rounded up to the + * next page, so any extra bytes from the file must be wiped.) + */ static unsigned long elf_map(struct file *filep, unsigned long addr, const struct elf_phdr *eppnt, int prot, int type, unsigned long total_size) @@ -387,6 +392,11 @@ static unsigned long elf_map(struct file *filep, unsigned long addr, return(map_addr); } +/* + * Map "eppnt->p_filesz" bytes from "filep" offset "eppnt->p_offset" + * into memory at "addr". Memory from "p_filesz" through "p_memsz" + * rounded up to the next page is zeroed. + */ static unsigned long elf_load(struct file *filep, unsigned long addr, const struct elf_phdr *eppnt, int prot, int type, unsigned long total_size) @@ -404,8 +414,12 @@ static unsigned long elf_load(struct file *filep, unsigned long addr, zero_end = map_addr + ELF_PAGEOFFSET(eppnt->p_vaddr) + eppnt->p_memsz; - /* Zero the end of the last mapped page */ - padzero(zero_start); + /* + * Zero the end of the last mapped page but ignore + * any errors if the segment isn't writable. + */ + if (padzero(zero_start) && (prot & PROT_WRITE)) + return -EFAULT; } } else { map_addr = zero_start = ELF_PAGESTART(addr);