From patchwork Mon Oct 9 19:15:40 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 9994119 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9898660223 for ; Mon, 9 Oct 2017 19:19:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8CF50284AA for ; Mon, 9 Oct 2017 19:19:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 81FB0286BF; Mon, 9 Oct 2017 19:19:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.3 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1C6A6284AA for ; Mon, 9 Oct 2017 19:19:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754830AbdJITTb (ORCPT ); Mon, 9 Oct 2017 15:19:31 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:38333 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754788AbdJITTH (ORCPT ); Mon, 9 Oct 2017 15:19:07 -0400 Received: by mail-pf0-f195.google.com with SMTP id a7so29879454pfj.5; Mon, 09 Oct 2017 12:19:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=HTincmMaw22oTX97ih7Dn/E4P9ceZ7Ga51nD9JdQPxw=; b=sN8Y5j/YwdYu0VL0dbUbp/Zi3PTfQXHjDIUS1miXgarq88bD2mQStqVvJT+DQgeBr7 NOlBm4SLoDVgjVULmJUIY3ql7RTncs1HyQk1dvVojXRlCRQKuxi4XvluFQ08YC4OKVgM fiQ5P4E+uu8E9eMcYvufUN5BVRMV0BVDxAE1ds9aap1m7VsNlmdox5/U8CM+7boVJ/Nv roHNPEFTa2joMMCNpwkT+grtYHV7yJA6sG7lyT7k3RhWgsrPF7izSikaSW1Iv2Sujzj7 B9t43CuceTkZFHGbbqcUp++pSyZe6Cq892ng/UyNtjx+OfbIutJGELVr9ltGWAHu60s9 xw8g== 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; bh=HTincmMaw22oTX97ih7Dn/E4P9ceZ7Ga51nD9JdQPxw=; b=gNWTK8srutTX7vvaNJjcO7VBbcRcW4yFcvJLoMO9AOyyfocwhslOfqQWi1KG+HEDYl xbLqe2raZ7OFZL17f17TGnYMKUJ5RnwdCALwqlYGPMv6hR2ECyzEt18UPPfzkIv/QElj 4eKkdev4Mzm4K5hk/DUGgSnXIebhQ0FHjLx7aO1OYbXZlnmYebZ+uMggNRRu93c8o+5n VLwy1jKsoZSqRiqtQ7AzUlfbnpJubg9mJwfl0WDrvzEHXnnL9ekkztL4zcZxFbHxW/Fv p6IsaLrnNoprBLIQCOlM5wKAWZNq5cRVkw3vieOcbSJ4Dr+aOt+v0y5SC6wAcztuVK8e IzVA== X-Gm-Message-State: AMCzsaXAqrod0Jgx3YI/EJG/EXV3vd2Ksgrzla2IcDrqKkjliWc7qtxx JIFnIPibf5gNLjyvj+zAyYd+m3Xu X-Google-Smtp-Source: AOwi7QCP8kBJ+cC3LtzTVt91OJGDuuJgmh+MzGJkqGi90tpZOGOuLuxm1YSgEQxM84kXwno6rElXiA== X-Received: by 10.99.66.196 with SMTP id p187mr10105456pga.0.1507576746263; Mon, 09 Oct 2017 12:19:06 -0700 (PDT) Received: from ebiggers-linuxstation.kir.corp.google.com ([100.66.174.81]) by smtp.gmail.com with ESMTPSA id n29sm17039819pgf.44.2017.10.09.12.19.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 09 Oct 2017 12:19:05 -0700 (PDT) From: Eric Biggers To: linux-fscrypt@vger.kernel.org, "Theodore Y . Ts'o" Cc: Jaegeuk Kim , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, Eric Biggers Subject: [PATCH v2 07/11] fscrypt: new helper function - fscrypt_file_open() Date: Mon, 9 Oct 2017 12:15:40 -0700 Message-Id: <20171009191544.43656-8-ebiggers3@gmail.com> X-Mailer: git-send-email 2.14.2.920.gcf0c67979c-goog In-Reply-To: <20171009191544.43656-1-ebiggers3@gmail.com> References: <20171009191544.43656-1-ebiggers3@gmail.com> Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a helper function which prepares to open a regular file which may be encrypted. It handles setting up the file's encryption key, then checking that the file's encryption policy matches that of its parent directory (if the parent directory is encrypted). It may be set as the ->open() method or it can be called from another ->open() method. Acked-by: Dave Chinner Signed-off-by: Eric Biggers --- fs/crypto/Makefile | 2 +- fs/crypto/hooks.c | 49 +++++++++++++++++++++++++++++++++++++++++ include/linux/fscrypt_notsupp.h | 9 ++++++++ include/linux/fscrypt_supp.h | 3 +++ 4 files changed, 62 insertions(+), 1 deletion(-) create mode 100644 fs/crypto/hooks.c diff --git a/fs/crypto/Makefile b/fs/crypto/Makefile index 9f6607f17b53..cb496989a6b6 100644 --- a/fs/crypto/Makefile +++ b/fs/crypto/Makefile @@ -1,4 +1,4 @@ obj-$(CONFIG_FS_ENCRYPTION) += fscrypto.o -fscrypto-y := crypto.o fname.o policy.o keyinfo.o +fscrypto-y := crypto.o fname.o hooks.o keyinfo.o policy.o fscrypto-$(CONFIG_BLOCK) += bio.o diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c new file mode 100644 index 000000000000..069088e91ea9 --- /dev/null +++ b/fs/crypto/hooks.c @@ -0,0 +1,49 @@ +/* + * fs/crypto/hooks.c + * + * Encryption hooks for higher-level filesystem operations. + */ + +#include +#include "fscrypt_private.h" + +/** + * fscrypt_file_open - prepare to open a possibly-encrypted regular file + * @inode: the inode being opened + * @filp: the struct file being set up + * + * Currently, an encrypted regular file can only be opened if its encryption key + * is available; access to the raw encrypted contents is not supported. + * Therefore, we first set up the inode's encryption key (if not already done) + * and return an error if it's unavailable. + * + * We also verify that if the parent directory (from the path via which the file + * is being opened) is encrypted, then the inode being opened uses the same + * encryption policy. This is needed as part of the enforcement that all files + * in an encrypted directory tree use the same encryption policy, as a + * protection against certain types of offline attacks. Note that this check is + * needed even when opening an *unencrypted* file, since it's forbidden to have + * an unencrypted file in an encrypted directory. + * + * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code + */ +int fscrypt_file_open(struct inode *inode, struct file *filp) +{ + int err; + struct dentry *dir; + + err = fscrypt_require_key(inode); + if (err) + return err; + + dir = dget_parent(file_dentry(filp)); + if (IS_ENCRYPTED(d_inode(dir)) && + !fscrypt_has_permitted_context(d_inode(dir), inode)) { + pr_warn_ratelimited("fscrypt: inconsistent encryption contexts: %lu/%lu", + d_inode(dir)->i_ino, inode->i_ino); + err = -EPERM; + } + dput(dir); + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_file_open); diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h index 7b390e356f7f..162da6517ac4 100644 --- a/include/linux/fscrypt_notsupp.h +++ b/include/linux/fscrypt_notsupp.h @@ -177,4 +177,13 @@ static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, return -EOPNOTSUPP; } +/* hooks.c */ + +static inline int fscrypt_file_open(struct inode *inode, struct file *filp) +{ + if (IS_ENCRYPTED(inode)) + return -EOPNOTSUPP; + return 0; +} + #endif /* _LINUX_FSCRYPT_NOTSUPP_H */ diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h index 5a90e5ef4687..fd2f6decaee4 100644 --- a/include/linux/fscrypt_supp.h +++ b/include/linux/fscrypt_supp.h @@ -143,4 +143,7 @@ extern void fscrypt_pullback_bio_page(struct page **, bool); extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t, unsigned int); +/* hooks.c */ +extern int fscrypt_file_open(struct inode *inode, struct file *filp); + #endif /* _LINUX_FSCRYPT_SUPP_H */