From patchwork Thu Jun 17 23:51:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 12329855 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E346EC49EA2 for ; Thu, 17 Jun 2021 23:51:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8ED2600D1 for ; Thu, 17 Jun 2021 23:51:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232347AbhFQXyA (ORCPT ); Thu, 17 Jun 2021 19:54:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231497AbhFQXx7 (ORCPT ); Thu, 17 Jun 2021 19:53:59 -0400 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E225C061767 for ; Thu, 17 Jun 2021 16:51:50 -0700 (PDT) Received: by mail-pl1-x631.google.com with SMTP id h12so3763386plf.4 for ; Thu, 17 Jun 2021 16:51:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LSGNn97SOZER5HbEMTzSBnn3cAj23nXQA/KZwmR95/E=; b=HlNcy4a/psBVA0WVEMlG1iHMejxNwmETL9Tv8aTY9I/5JZoiIMWf3LCwQ/G3pWNi+4 4q13ruSb66vwwKD9KhCFMbL/xWOq+API5DphzuA2ESft3Us05nU0/4dO++lI4Q9SJF2i 2ZLh+f3ad6H8LzMsuhAea9NV2ZQtoaWO9ORrYXE42SBTpopKqTyHOY79rzE8gEomEQ5N +CHdqXz9S/YDvdNF3k24FByhN5BLbd3r7jiaoRB5aUpN0XF8Cm3R1DiewxoJV171kv7A TTqEsqJ5Sxqw+1hSYYaFHMOHcp3nQzpgvNCqjCARTYQUJppeO7mI9Xzn0EcK+Cn34t8c fqQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=LSGNn97SOZER5HbEMTzSBnn3cAj23nXQA/KZwmR95/E=; b=hh5HS3c0X37MJtyL/Kb8YwONGM7S1uXMEsn2vO46dakvjmYCHL3hlneKNELxYIa9NH R8ZfPKd2Wq+IrbyStTnIGzSy80EXH1azXKW49N2wx4lRbgn7GnGyokRDEauqw4DNETac eFPXXxghD4KGL6WfufBu+NW3b8sEBUtA8tc+qKI8c3fYEeT5UFs3criZPePJq2crNOPc yokY51mI0yOWnqYnyyFJN9fV1P3bwbcb4CxgaB/2U6WltAWHxjcm32oqFSdAI/Zqgn0D gsjT7g+l7QCb5fs7mbKj5qwII0ZAZRLVl83Ql6RV4rwBqYRpivzttRve7Olkoem5gJ0a Y9yg== X-Gm-Message-State: AOAM532M86U3QEAd6RRqdrKpd9D9+3xFUDeHA4rYe3XrXGBO/+T2hoNK YTKxw47KxylTzreICxQo97VwkA== X-Google-Smtp-Source: ABdhPJyevOLO1ohJ+DlEjg8E72npcSqm9zxCSCI8hO3y7hzAoR89SokKt/1VQg+/bqjMD/J3u/1OTw== X-Received: by 2002:a17:90a:4a8f:: with SMTP id f15mr6503975pjh.76.1623973910066; Thu, 17 Jun 2021 16:51:50 -0700 (PDT) Received: from relinquished.tfbnw.net ([2620:10d:c090:400::5:2f0e]) by smtp.gmail.com with ESMTPSA id a187sm6087517pfb.66.2021.06.17.16.51.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Jun 2021 16:51:49 -0700 (PDT) From: Omar Sandoval To: linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, Al Viro Cc: Linus Torvalds , linux-api@vger.kernel.org, kernel-team@fb.com Subject: [PATCH RESEND x3 v9 2/9] fs: add O_ALLOW_ENCODED open flag Date: Thu, 17 Jun 2021 16:51:25 -0700 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Omar Sandoval The upcoming RWF_ENCODED operation introduces some security concerns: 1. Compressed writes will pass arbitrary data to decompression algorithms in the kernel. 2. Compressed reads can leak truncated/hole punched data. Therefore, we need to require privilege for RWF_ENCODED. It's not possible to do the permissions checks at the time of the read or write because, e.g., io_uring submits IO from a worker thread. So, add an open flag which requires CAP_SYS_ADMIN. It can also be set and cleared with fcntl(). The flag is not cleared in any way on fork or exec. Note that the usual issue that unknown open flags are ignored doesn't really matter for O_ALLOW_ENCODED; if the kernel doesn't support O_ALLOW_ENCODED, then it doesn't support RWF_ENCODED, either. Reviewed-by: Josef Bacik Signed-off-by: Omar Sandoval --- arch/alpha/include/uapi/asm/fcntl.h | 1 + arch/parisc/include/uapi/asm/fcntl.h | 1 + arch/sparc/include/uapi/asm/fcntl.h | 1 + fs/fcntl.c | 10 ++++++++-- fs/namei.c | 4 ++++ include/linux/fcntl.h | 2 +- include/uapi/asm-generic/fcntl.h | 4 ++++ 7 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/alpha/include/uapi/asm/fcntl.h b/arch/alpha/include/uapi/asm/fcntl.h index 50bdc8e8a271..391e0d112e41 100644 --- a/arch/alpha/include/uapi/asm/fcntl.h +++ b/arch/alpha/include/uapi/asm/fcntl.h @@ -34,6 +34,7 @@ #define O_PATH 040000000 #define __O_TMPFILE 0100000000 +#define O_ALLOW_ENCODED 0200000000 #define F_GETLK 7 #define F_SETLK 8 diff --git a/arch/parisc/include/uapi/asm/fcntl.h b/arch/parisc/include/uapi/asm/fcntl.h index 03dee816cb13..0feb31faaefa 100644 --- a/arch/parisc/include/uapi/asm/fcntl.h +++ b/arch/parisc/include/uapi/asm/fcntl.h @@ -19,6 +19,7 @@ #define O_PATH 020000000 #define __O_TMPFILE 040000000 +#define O_ALLOW_ENCODED 0100000000 #define F_GETLK64 8 #define F_SETLK64 9 diff --git a/arch/sparc/include/uapi/asm/fcntl.h b/arch/sparc/include/uapi/asm/fcntl.h index 67dae75e5274..ac3e8c9cb32c 100644 --- a/arch/sparc/include/uapi/asm/fcntl.h +++ b/arch/sparc/include/uapi/asm/fcntl.h @@ -37,6 +37,7 @@ #define O_PATH 0x1000000 #define __O_TMPFILE 0x2000000 +#define O_ALLOW_ENCODED 0x8000000 #define F_GETOWN 5 /* for sockets. */ #define F_SETOWN 6 /* for sockets. */ diff --git a/fs/fcntl.c b/fs/fcntl.c index dfc72f15be7f..eca4eb008194 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -31,7 +31,8 @@ #include #include -#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) +#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME | \ + O_ALLOW_ENCODED) static int setfl(int fd, struct file * filp, unsigned long arg) { @@ -50,6 +51,11 @@ static int setfl(int fd, struct file * filp, unsigned long arg) if (!inode_owner_or_capable(file_mnt_user_ns(filp), inode)) return -EPERM; + /* O_ALLOW_ENCODED can only be set by superuser */ + if ((arg & O_ALLOW_ENCODED) && !(filp->f_flags & O_ALLOW_ENCODED) && + !capable(CAP_SYS_ADMIN)) + return -EPERM; + /* required for strict SunOS emulation */ if (O_NONBLOCK != O_NDELAY) if (arg & O_NDELAY) @@ -1043,7 +1049,7 @@ static int __init fcntl_init(void) * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY * is defined as O_NONBLOCK on some platforms and not on others. */ - BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != + BUILD_BUG_ON(22 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32( (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | __FMODE_EXEC | __FMODE_NONOTIFY)); diff --git a/fs/namei.c b/fs/namei.c index 79b0ff9b151e..b05f121b3947 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2997,6 +2997,10 @@ static int may_open(struct user_namespace *mnt_userns, const struct path *path, if (flag & O_NOATIME && !inode_owner_or_capable(mnt_userns, inode)) return -EPERM; + /* O_ALLOW_ENCODED can only be set by superuser */ + if ((flag & O_ALLOW_ENCODED) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + return 0; } diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index 766fcd973beb..2cd6a9185d4c 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -10,7 +10,7 @@ (O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC | \ O_APPEND | O_NDELAY | O_NONBLOCK | __O_SYNC | O_DSYNC | \ FASYNC | O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | \ - O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE) + O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE | O_ALLOW_ENCODED) /* List of all valid flags for the how->upgrade_mask argument: */ #define VALID_UPGRADE_FLAGS \ diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h index 9dc0bf0c5a6e..75321c7a66ac 100644 --- a/include/uapi/asm-generic/fcntl.h +++ b/include/uapi/asm-generic/fcntl.h @@ -89,6 +89,10 @@ #define __O_TMPFILE 020000000 #endif +#ifndef O_ALLOW_ENCODED +#define O_ALLOW_ENCODED 040000000 +#endif + /* a horrid kludge trying to make sure that this will fail on old kernels */ #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) #define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT)