From patchwork Wed Mar 20 18:39:09 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10862407 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A25936C2 for ; Wed, 20 Mar 2019 18:40:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8802029BA0 for ; Wed, 20 Mar 2019 18:40:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7BE0C29E18; Wed, 20 Mar 2019 18:40:24 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham 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 E78C529BA0 for ; Wed, 20 Mar 2019 18:40:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbfCTSkX (ORCPT ); Wed, 20 Mar 2019 14:40:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:36558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727265AbfCTSkP (ORCPT ); Wed, 20 Mar 2019 14:40:15 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1173F2175B; Wed, 20 Mar 2019 18:40:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553107214; bh=+vU7rSc55LpXe0KhhD1OnU9UyCaQvdmdHhdtI2vPxAI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Em8aMCDX+SQHXQkctoEz2RFiEK6yg6BTx1PR+EC02wPpxsPhDWfyJrKUliE4IrUty ViCRdEbiv3evrzQFa1ZOagJn1SuWQ4wyy1m+yOs+WjqMXe5kPRijkcT3wpkwNJgYI7 PLp86dUKUd1Q5xupnOM2CBJuPttxXtCZjQKPf6z8= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: [PATCH v2 1/5] fscrypt: clean up and improve dentry revalidation Date: Wed, 20 Mar 2019 11:39:09 -0700 Message-Id: <20190320183913.12686-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.225.g810b269d1ac-goog In-Reply-To: <20190320183913.12686-1-ebiggers@kernel.org> References: <20190320183913.12686-1-ebiggers@kernel.org> MIME-Version: 1.0 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 Make various improvements to fscrypt dentry revalidation: - Don't try to handle the case where the per-directory key is removed, as this can't happen without the inode (and dentries) being evicted. - Flag ciphertext dentries rather than plaintext dentries, since it's ciphertext dentries that need the special handling. - Avoid doing unnecessary work for non-ciphertext dentries. - When revalidating ciphertext dentries, try to set up the directory's i_crypt_info to make sure the key is really still absent, rather than invalidating all negative dentries as the previous code did. An old comment suggested we can't do this for locking reasons, but AFAICT this comment was outdated and it actually works fine. Signed-off-by: Eric Biggers --- fs/crypto/crypto.c | 58 +++++++++++++++++++++-------------------- fs/crypto/hooks.c | 4 +-- include/linux/dcache.h | 2 +- include/linux/fscrypt.h | 6 ++--- 4 files changed, 35 insertions(+), 35 deletions(-) diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index 4dc788e3bc96b..3fc84bf2b1e52 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -313,45 +313,47 @@ int fscrypt_decrypt_page(const struct inode *inode, struct page *page, EXPORT_SYMBOL(fscrypt_decrypt_page); /* - * Validate dentries for encrypted directories to make sure we aren't - * potentially caching stale data after a key has been added or - * removed. + * Validate dentries in encrypted directories to make sure we aren't potentially + * caching stale dentries after a key has been added. */ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) { struct dentry *dir; - int dir_has_key, cached_with_key; + int err; + int valid; + + /* + * Plaintext names are always valid, since fscrypt doesn't support + * reverting to ciphertext names without evicting the directory's inode + * -- which implies eviction of the dentries in the directory. + */ + if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME)) + return 1; + + /* + * Ciphertext name; valid if the directory's key is still unavailable. + * + * Although fscrypt forbids rename() on ciphertext names, we still must + * use dget_parent() here rather than use ->d_parent directly. That's + * because a corrupted fs image may contain directory hard links, which + * the VFS handles by moving the directory's dentry tree in the dcache + * each time ->lookup() finds the directory and it already has a dentry + * elsewhere. Thus ->d_parent can be changing, and we must safely grab + * a reference to some ->d_parent to prevent it from being freed. + */ if (flags & LOOKUP_RCU) return -ECHILD; dir = dget_parent(dentry); - if (!IS_ENCRYPTED(d_inode(dir))) { - dput(dir); - return 0; - } - - spin_lock(&dentry->d_lock); - cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY; - spin_unlock(&dentry->d_lock); - dir_has_key = (d_inode(dir)->i_crypt_info != NULL); + err = fscrypt_get_encryption_info(d_inode(dir)); + valid = (d_inode(dir)->i_crypt_info == NULL); dput(dir); - /* - * If the dentry was cached without the key, and it is a - * negative dentry, it might be a valid name. We can't check - * if the key has since been made available due to locking - * reasons, so we fail the validation so ext4_lookup() can do - * this check. - * - * We also fail the validation if the dentry was created with - * the key present, but we no longer have the key, or vice versa. - */ - if ((!cached_with_key && d_is_negative(dentry)) || - (!cached_with_key && dir_has_key) || - (cached_with_key && !dir_has_key)) - return 0; - return 1; + if (err < 0) + return err; + + return valid; } const struct dentry_operations fscrypt_d_ops = { diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 56debb1fcf5eb..a9492f75bbe13 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -101,9 +101,9 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry) if (err) return err; - if (fscrypt_has_encryption_key(dir)) { + if (!fscrypt_has_encryption_key(dir)) { spin_lock(&dentry->d_lock); - dentry->d_flags |= DCACHE_ENCRYPTED_WITH_KEY; + dentry->d_flags |= DCACHE_ENCRYPTED_NAME; spin_unlock(&dentry->d_lock); } diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 60996e64c5798..9b3b75d3bd211 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -212,7 +212,7 @@ struct dentry_operations { #define DCACHE_MAY_FREE 0x00800000 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ -#define DCACHE_ENCRYPTED_WITH_KEY 0x02000000 /* dir is encrypted with a valid key */ +#define DCACHE_ENCRYPTED_NAME 0x02000000 /* Encrypted name (dir key was unavailable) */ #define DCACHE_OP_REAL 0x04000000 #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */ diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index e5194fc3983e9..5a0c3fee1ea2b 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -545,10 +545,8 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir, * filenames are presented in encrypted form. Therefore, we'll try to set up * the directory's encryption key, but even without it the lookup can continue. * - * To allow invalidating stale dentries if the directory's encryption key is - * added later, we also install a custom ->d_revalidate() method and use the - * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a - * plaintext name (flag set) or a ciphertext name (flag cleared). + * This also installs a custom ->d_revalidate() method which will invalidate the + * dentry if it was created without the key and the key is later added. * * Return: 0 on success, -errno if a problem occurred while setting up the * encryption key From patchwork Wed Mar 20 18:39:10 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10862403 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 322111515 for ; Wed, 20 Mar 2019 18:40:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 118BA29BA0 for ; Wed, 20 Mar 2019 18:40:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 05A1329E16; Wed, 20 Mar 2019 18:40:23 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham 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 9813F29BA0 for ; Wed, 20 Mar 2019 18:40:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727513AbfCTSkQ (ORCPT ); Wed, 20 Mar 2019 14:40:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:36580 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727271AbfCTSkQ (ORCPT ); Wed, 20 Mar 2019 14:40:16 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6FE002184D; Wed, 20 Mar 2019 18:40:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553107214; bh=gw7hzL2AWULkDpqnra8Btn4G36d3e2QHfPxFEHxuM+Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qye2SP4yuT5Mn/ZZSTmiWX1eRJQP2xdtgpmqL0MfroLwNJuTe0KmM5BHjAxFeQ6GS dueVl8MsoLVeMGaUZc3y+gRl9R5CqJltDFCcsy4uJBrCUYtZycfq/+HWHtxm1xO3X7 xODg9CUj76XYwKA0NZbwW9jxbvBq/M5BugWipLIE= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: [PATCH v2 2/5] fscrypt: fix race allowing rename() and link() of ciphertext dentries Date: Wed, 20 Mar 2019 11:39:10 -0700 Message-Id: <20190320183913.12686-3-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.225.g810b269d1ac-goog In-Reply-To: <20190320183913.12686-1-ebiggers@kernel.org> References: <20190320183913.12686-1-ebiggers@kernel.org> MIME-Version: 1.0 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 Close some race conditions where fscrypt allowed rename() and link() on ciphertext dentries that had been looked up just prior to the key being concurrently added. It's better to return -ENOKEY in this case. This avoids doing the nonsensical thing of encrypting the names a second time when searching for the actual on-disk dir entries. It also guarantees that DCACHE_ENCRYPTED_NAME dentries are never rename()d, so the dcache won't have support all possible combinations of moving DCACHE_ENCRYPTED_NAME around during __d_move(). Signed-off-by: Eric Biggers --- fs/crypto/hooks.c | 12 +++++++++++- include/linux/fscrypt.h | 9 +++++---- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index a9492f75bbe13..2e7498a821a48 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -49,7 +49,8 @@ int fscrypt_file_open(struct inode *inode, struct file *filp) } EXPORT_SYMBOL_GPL(fscrypt_file_open); -int __fscrypt_prepare_link(struct inode *inode, struct inode *dir) +int __fscrypt_prepare_link(struct inode *inode, struct inode *dir, + struct dentry *dentry) { int err; @@ -57,6 +58,10 @@ int __fscrypt_prepare_link(struct inode *inode, struct inode *dir) if (err) return err; + /* ... in case we looked up ciphertext name before key was added */ + if (dentry->d_flags & DCACHE_ENCRYPTED_NAME) + return -ENOKEY; + if (!fscrypt_has_permitted_context(dir, inode)) return -EXDEV; @@ -78,6 +83,11 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, if (err) return err; + /* ... in case we looked up ciphertext name(s) before key was added */ + if ((old_dentry->d_flags | new_dentry->d_flags) & + DCACHE_ENCRYPTED_NAME) + return -ENOKEY; + if (old_dir != new_dir) { if (IS_ENCRYPTED(new_dir) && !fscrypt_has_permitted_context(new_dir, diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 5a0c3fee1ea2b..4ad7a856e0f1c 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -214,7 +214,8 @@ extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t, /* hooks.c */ extern int fscrypt_file_open(struct inode *inode, struct file *filp); -extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir); +extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir, + struct dentry *dentry); extern int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, @@ -401,8 +402,8 @@ static inline int fscrypt_file_open(struct inode *inode, struct file *filp) return 0; } -static inline int __fscrypt_prepare_link(struct inode *inode, - struct inode *dir) +static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir, + struct dentry *dentry) { return -EOPNOTSUPP; } @@ -497,7 +498,7 @@ static inline int fscrypt_prepare_link(struct dentry *old_dentry, struct dentry *dentry) { if (IS_ENCRYPTED(dir)) - return __fscrypt_prepare_link(d_inode(old_dentry), dir); + return __fscrypt_prepare_link(d_inode(old_dentry), dir, dentry); return 0; } From patchwork Wed Mar 20 18:39:11 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10862391 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 70FC41515 for ; Wed, 20 Mar 2019 18:40:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 55C6329C2C for ; Wed, 20 Mar 2019 18:40:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 49C0A29E16; Wed, 20 Mar 2019 18:40:19 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham 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 C773529C2C for ; Wed, 20 Mar 2019 18:40:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727531AbfCTSkR (ORCPT ); Wed, 20 Mar 2019 14:40:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:36608 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727307AbfCTSkQ (ORCPT ); Wed, 20 Mar 2019 14:40:16 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CD93B21873; Wed, 20 Mar 2019 18:40:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553107215; bh=GVgaWnQRVDs7JRYe6xnoJZc6eiXCKyqXo6bHkLGC1Rk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0Y8/2ajXXylCpL94BCn1e/yyk7Dy9TuPTbDGiY3kRwbwE3ldpc1fNoGMtRj8w/boP S56eq7xpwINi4YBF4SduNyFX1FQNMh0TY9Rlc75/i647zHz/s68hEW2dKCTJcLZZay ULqAZ530hqJSJNLGGnuZOzF01ai2/kfpobmEKHHQ= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: [PATCH v2 3/5] fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory Date: Wed, 20 Mar 2019 11:39:11 -0700 Message-Id: <20190320183913.12686-4-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.225.g810b269d1ac-goog In-Reply-To: <20190320183913.12686-1-ebiggers@kernel.org> References: <20190320183913.12686-1-ebiggers@kernel.org> MIME-Version: 1.0 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 Make __d_move() clear DCACHE_ENCRYPTED_NAME on the source dentry. This is needed for when d_splice_alias() moves a directory's encrypted alias to its decrypted alias as a result of the encryption key being added. Otherwise, the decrypted alias will incorrectly be invalidated on the next lookup, causing problems such as unmounting a mount the user just mount()ed there. Note that we don't have to support arbitrary moves of this flag because fscrypt doesn't allow dentries with DCACHE_ENCRYPTED_NAME to be the source or target of a rename(). Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") Reported-by: Sarthak Kukreti Signed-off-by: Eric Biggers --- fs/dcache.c | 2 ++ include/linux/fscrypt.h | 16 ++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/fs/dcache.c b/fs/dcache.c index aac41adf47433..647e6ed426e20 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -2795,6 +2796,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target, list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); __d_rehash(dentry); fsnotify_update_flags(dentry); + fscrypt_handle_d_move(dentry); write_seqcount_end(&target->d_seq); write_seqcount_end(&dentry->d_seq); diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 4ad7a856e0f1c..39bd2619a3424 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -88,6 +88,18 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode) inode->i_sb->s_cop->dummy_context(inode); } +/* + * When d_splice_alias() moves a directory's encrypted alias to its decrypted + * alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME + * must be cleared. Note that we don't have to support arbitrary moves of this + * flag because fscrypt doesn't allow encrypted aliases to be the source or + * target of a rename(). + */ +static inline void fscrypt_handle_d_move(struct dentry *dentry) +{ + dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME; +} + /* crypto.c */ extern void fscrypt_enqueue_decrypt_work(struct work_struct *); extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t); @@ -243,6 +255,10 @@ static inline bool fscrypt_dummy_context_enabled(struct inode *inode) return false; } +static inline void fscrypt_handle_d_move(struct dentry *dentry) +{ +} + /* crypto.c */ static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work) { From patchwork Wed Mar 20 18:39:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10862397 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4C9961515 for ; Wed, 20 Mar 2019 18:40:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3CFD429E67 for ; Wed, 20 Mar 2019 18:40:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 312C329E3F; Wed, 20 Mar 2019 18:40:22 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI 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 D450D29BA0 for ; Wed, 20 Mar 2019 18:40:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727524AbfCTSkR (ORCPT ); Wed, 20 Mar 2019 14:40:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:36614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727499AbfCTSkQ (ORCPT ); Wed, 20 Mar 2019 14:40:16 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 37A1321841; Wed, 20 Mar 2019 18:40:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553107215; bh=QPdDcwv8QIQHVxEXZR8gR3cRzKCH9Mf22Cf6SiteznU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wVVDHm0uotjkjfN448/7q/NYGAclTe2c9aCMPtDz3xBWYQ1I4tqAfAMUu0syQxWp6 hiqp9xi0Wr7Sc5TzlpXB/4D2JchsoJF6uMNCfC+XhByuA+sbOHSIyQVH+u/y964RLk P1GoxbBTjV1z6a5W9PGbwRmc6NXa2V2VBRqql7pY= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: [PATCH v2 4/5] fscrypt: only set dentry_operations on ciphertext dentries Date: Wed, 20 Mar 2019 11:39:12 -0700 Message-Id: <20190320183913.12686-5-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.225.g810b269d1ac-goog In-Reply-To: <20190320183913.12686-1-ebiggers@kernel.org> References: <20190320183913.12686-1-ebiggers@kernel.org> MIME-Version: 1.0 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 Plaintext dentries are always valid, so only set fscrypt_d_ops on ciphertext dentries. Besides marginally improved performance, this allows overlayfs to use an fscrypt-encrypted upperdir, provided that all the following are true: (1) The fscrypt encryption key is placed in the keyring before mounting overlayfs, and remains while the overlayfs is mounted. (2) The overlayfs workdir uses the same encryption policy. (3) No dentries for the ciphertext names of subdirectories have been created in the upperdir or workdir yet. (Since otherwise d_splice_alias() will reuse the old dentry with ->d_op set.) One potential use case is using an ephemeral encryption key to encrypt all files created or changed by a container, so that they can be securely erased ("crypto-shredded") after the container stops. Signed-off-by: Eric Biggers --- fs/crypto/hooks.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 2e7498a821a48..9d8910e86ee5d 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -115,9 +115,8 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry) spin_lock(&dentry->d_lock); dentry->d_flags |= DCACHE_ENCRYPTED_NAME; spin_unlock(&dentry->d_lock); + d_set_d_op(dentry, &fscrypt_d_ops); } - - d_set_d_op(dentry, &fscrypt_d_ops); return 0; } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); From patchwork Wed Mar 20 18:39:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10862399 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5A81517E0 for ; Wed, 20 Mar 2019 18:40:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 30D6229E16 for ; Wed, 20 Mar 2019 18:40:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1F97829E18; Wed, 20 Mar 2019 18:40:22 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham 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 10A5829C2C for ; Wed, 20 Mar 2019 18:40:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727537AbfCTSkT (ORCPT ); Wed, 20 Mar 2019 14:40:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:36620 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726812AbfCTSkR (ORCPT ); Wed, 20 Mar 2019 14:40:17 -0400 Received: from ebiggers-linuxstation.mtv.corp.google.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 963BF218A2; Wed, 20 Mar 2019 18:40:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553107215; bh=jEJ17DfyejGc8TI94VO3u5nCjiy43EqYCoVtJ5ZK1/0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vqrHZmW8JsWjo3WETOCU5/G7NY+mDXYDNWtjlMn5ZPfok64BD7AGrR5M5B45ckX8U 0uNbpwNs3K1BtVRrt4t1frNFnzRyxwMxpHaoILDn3gjAqgyD7Icw4K6FPD2zyZCh2L SOl1P/d+zpOfUDUMq8nXqOd/5MNczqLrvnQ71nVY= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-unionfs@vger.kernel.org, Sarthak Kukreti , Gao Xiang Subject: [PATCH v2 5/5] fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext Date: Wed, 20 Mar 2019 11:39:13 -0700 Message-Id: <20190320183913.12686-6-ebiggers@kernel.org> X-Mailer: git-send-email 2.21.0.225.g810b269d1ac-goog In-Reply-To: <20190320183913.12686-1-ebiggers@kernel.org> References: <20190320183913.12686-1-ebiggers@kernel.org> MIME-Version: 1.0 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 ->lookup() in an encrypted directory begins as follows: 1. fscrypt_prepare_lookup(): a. Try to load the directory's encryption key. b. If the key is unavailable, mark the dentry as a ciphertext name via d_flags. 2. fscrypt_setup_filename(): a. Try to load the directory's encryption key. b. If the key is available, encrypt the name (treated as a plaintext name) to get the on-disk name. Otherwise decode the name (treated as a ciphertext name) to get the on-disk name. But if the key is concurrently added, it may be found at (2a) but not at (1a). In this case, the dentry will be wrongly marked as a ciphertext name even though it was actually treated as plaintext. This will cause the dentry to be wrongly invalidated on the next lookup, potentially causing problems. For example, if the racy ->lookup() was part of sys_mount(), then the new mount will be detached when anything tries to access it. This is despite the mountpoint having a plaintext path, which should remain valid now that the key was added. Of course, this is only possible if there's a userspace race. Still, the additional kernel-side race is confusing and unexpected. Close the kernel-side race by changing fscrypt_prepare_lookup() to also set the on-disk filename (step 2b), consistent with the d_flags update. Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") Signed-off-by: Eric Biggers --- fs/crypto/fname.c | 1 + fs/crypto/hooks.c | 11 +++--- fs/ext4/ext4.h | 62 +++++++++++++++++++++++++-------- fs/ext4/namei.c | 76 ++++++++++++++++++++++++++++------------- fs/f2fs/namei.c | 17 +++++---- fs/ubifs/dir.c | 8 ++--- include/linux/fscrypt.h | 30 ++++++++++------ 7 files changed, 139 insertions(+), 66 deletions(-) diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 7ff40a73dbece..dea65c091f713 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -356,6 +356,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, } if (!lookup) return -ENOKEY; + fname->is_ciphertext_name = true; /* * We don't have the key and we are doing a lookup; decode the diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 9d8910e86ee5d..042d5b44f4ed9 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -104,20 +104,21 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, } EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename); -int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry) +int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, + struct fscrypt_name *fname) { - int err = fscrypt_get_encryption_info(dir); + int err = fscrypt_setup_filename(dir, &dentry->d_name, 1, fname); - if (err) + if (err && err != -ENOENT) return err; - if (!fscrypt_has_encryption_key(dir)) { + if (fname->is_ciphertext_name) { spin_lock(&dentry->d_lock); dentry->d_flags |= DCACHE_ENCRYPTED_NAME; spin_unlock(&dentry->d_lock); d_set_d_op(dentry, &fscrypt_d_ops); } - return 0; + return err; } EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup); diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 82ffdacdc7fac..e64a4ee96d30a 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2287,23 +2287,47 @@ extern unsigned ext4_free_clusters_after_init(struct super_block *sb, ext4_fsblk_t ext4_inode_to_goal_block(struct inode *); #ifdef CONFIG_FS_ENCRYPTION +static inline void ext4_fname_from_fscrypt_name(struct ext4_filename *dst, + const struct fscrypt_name *src) +{ + memset(dst, 0, sizeof(*dst)); + + dst->usr_fname = src->usr_fname; + dst->disk_name = src->disk_name; + dst->hinfo.hash = src->hash; + dst->hinfo.minor_hash = src->minor_hash; + dst->crypto_buf = src->crypto_buf; +} + static inline int ext4_fname_setup_filename(struct inode *dir, - const struct qstr *iname, - int lookup, struct ext4_filename *fname) + const struct qstr *iname, + int lookup, + struct ext4_filename *fname) { struct fscrypt_name name; int err; - memset(fname, 0, sizeof(struct ext4_filename)); - err = fscrypt_setup_filename(dir, iname, lookup, &name); + if (err) + return err; - fname->usr_fname = name.usr_fname; - fname->disk_name = name.disk_name; - fname->hinfo.hash = name.hash; - fname->hinfo.minor_hash = name.minor_hash; - fname->crypto_buf = name.crypto_buf; - return err; + ext4_fname_from_fscrypt_name(fname, &name); + return 0; +} + +static inline int ext4_fname_prepare_lookup(struct inode *dir, + struct dentry *dentry, + struct ext4_filename *fname) +{ + struct fscrypt_name name; + int err; + + err = fscrypt_prepare_lookup(dir, dentry, &name); + if (err) + return err; + + ext4_fname_from_fscrypt_name(fname, &name); + return 0; } static inline void ext4_fname_free_filename(struct ext4_filename *fname) @@ -2317,19 +2341,27 @@ static inline void ext4_fname_free_filename(struct ext4_filename *fname) fname->usr_fname = NULL; fname->disk_name.name = NULL; } -#else +#else /* !CONFIG_FS_ENCRYPTION */ static inline int ext4_fname_setup_filename(struct inode *dir, - const struct qstr *iname, - int lookup, struct ext4_filename *fname) + const struct qstr *iname, + int lookup, + struct ext4_filename *fname) { fname->usr_fname = iname; fname->disk_name.name = (unsigned char *) iname->name; fname->disk_name.len = iname->len; return 0; } -static inline void ext4_fname_free_filename(struct ext4_filename *fname) { } -#endif +static inline int ext4_fname_prepare_lookup(struct inode *dir, + struct dentry *dentry, + struct ext4_filename *fname) +{ + return ext4_fname_setup_filename(dir, &dentry->d_name, 1, fname); +} + +static inline void ext4_fname_free_filename(struct ext4_filename *fname) { } +#endif /* !CONFIG_FS_ENCRYPTION */ /* dir.c */ extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *, diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 980166a8122a6..3ba6f30db8d92 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1327,7 +1327,7 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block, } /* - * ext4_find_entry() + * __ext4_find_entry() * * finds an entry in the specified directory with the wanted name. It * returns the cache buffer in which the entry was found, and the entry @@ -1337,39 +1337,32 @@ static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block, * The returned buffer_head has ->b_count elevated. The caller is expected * to brelse() it when appropriate. */ -static struct buffer_head * ext4_find_entry (struct inode *dir, - const struct qstr *d_name, - struct ext4_dir_entry_2 **res_dir, - int *inlined) +static struct buffer_head *__ext4_find_entry(struct inode *dir, + struct ext4_filename *fname, + struct ext4_dir_entry_2 **res_dir, + int *inlined) { struct super_block *sb; struct buffer_head *bh_use[NAMEI_RA_SIZE]; struct buffer_head *bh, *ret = NULL; ext4_lblk_t start, block; - const u8 *name = d_name->name; + const u8 *name = fname->usr_fname->name; size_t ra_max = 0; /* Number of bh's in the readahead buffer, bh_use[] */ size_t ra_ptr = 0; /* Current index into readahead buffer */ ext4_lblk_t nblocks; int i, namelen, retval; - struct ext4_filename fname; *res_dir = NULL; sb = dir->i_sb; - namelen = d_name->len; + namelen = fname->usr_fname->len; if (namelen > EXT4_NAME_LEN) return NULL; - retval = ext4_fname_setup_filename(dir, d_name, 1, &fname); - if (retval == -ENOENT) - return NULL; - if (retval) - return ERR_PTR(retval); - if (ext4_has_inline_data(dir)) { int has_inline_data = 1; - ret = ext4_find_inline_entry(dir, &fname, res_dir, + ret = ext4_find_inline_entry(dir, fname, res_dir, &has_inline_data); if (has_inline_data) { if (inlined) @@ -1389,7 +1382,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir, goto restart; } if (is_dx(dir)) { - ret = ext4_dx_find_entry(dir, &fname, res_dir); + ret = ext4_dx_find_entry(dir, fname, res_dir); /* * On success, or if the error was file not found, * return. Otherwise, fall back to doing a search the @@ -1453,7 +1446,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir, goto cleanup_and_exit; } set_buffer_verified(bh); - i = search_dirblock(bh, dir, &fname, + i = search_dirblock(bh, dir, fname, block << EXT4_BLOCK_SIZE_BITS(sb), res_dir); if (i == 1) { EXT4_I(dir)->i_dir_start_lookup = block; @@ -1484,10 +1477,50 @@ static struct buffer_head * ext4_find_entry (struct inode *dir, /* Clean up the read-ahead blocks */ for (; ra_ptr < ra_max; ra_ptr++) brelse(bh_use[ra_ptr]); - ext4_fname_free_filename(&fname); return ret; } +static struct buffer_head *ext4_find_entry(struct inode *dir, + const struct qstr *d_name, + struct ext4_dir_entry_2 **res_dir, + int *inlined) +{ + int err; + struct ext4_filename fname; + struct buffer_head *bh; + + err = ext4_fname_setup_filename(dir, d_name, 1, &fname); + if (err == -ENOENT) + return NULL; + if (err) + return ERR_PTR(err); + + bh = __ext4_find_entry(dir, &fname, res_dir, inlined); + + ext4_fname_free_filename(&fname); + return bh; +} + +static struct buffer_head *ext4_lookup_entry(struct inode *dir, + struct dentry *dentry, + struct ext4_dir_entry_2 **res_dir) +{ + int err; + struct ext4_filename fname; + struct buffer_head *bh; + + err = ext4_fname_prepare_lookup(dir, dentry, &fname); + if (err == -ENOENT) + return NULL; + if (err) + return ERR_PTR(err); + + bh = __ext4_find_entry(dir, &fname, res_dir, NULL); + + ext4_fname_free_filename(&fname); + return bh; +} + static struct buffer_head * ext4_dx_find_entry(struct inode *dir, struct ext4_filename *fname, struct ext4_dir_entry_2 **res_dir) @@ -1546,16 +1579,11 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi struct inode *inode; struct ext4_dir_entry_2 *de; struct buffer_head *bh; - int err; - - err = fscrypt_prepare_lookup(dir, dentry, flags); - if (err) - return ERR_PTR(err); if (dentry->d_name.len > EXT4_NAME_LEN) return ERR_PTR(-ENAMETOOLONG); - bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL); + bh = ext4_lookup_entry(dir, dentry, &de); if (IS_ERR(bh)) return ERR_CAST(bh); inode = NULL; diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index f5e34e4670031..c3e8a901d47ac 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -436,19 +436,23 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry, nid_t ino = -1; int err = 0; unsigned int root_ino = F2FS_ROOT_INO(F2FS_I_SB(dir)); + struct fscrypt_name fname; trace_f2fs_lookup_start(dir, dentry, flags); - err = fscrypt_prepare_lookup(dir, dentry, flags); - if (err) - goto out; - if (dentry->d_name.len > F2FS_NAME_LEN) { err = -ENAMETOOLONG; goto out; } - de = f2fs_find_entry(dir, &dentry->d_name, &page); + err = fscrypt_prepare_lookup(dir, dentry, &fname); + if (err == -ENOENT) + goto out_splice; + if (err) + goto out; + de = __f2fs_find_entry(dir, &fname, &page); + fscrypt_free_filename(&fname); + if (!de) { if (IS_ERR(page)) { err = PTR_ERR(page); @@ -488,8 +492,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry, } out_splice: new = d_splice_alias(inode, dentry); - if (IS_ERR(new)) - err = PTR_ERR(new); + err = PTR_ERR_OR_ZERO(new); trace_f2fs_lookup_end(dir, dentry, ino, err); return new; out_iput: diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 5767b373a8ffb..b73de6d04fa3e 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -220,11 +220,9 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry, dbg_gen("'%pd' in dir ino %lu", dentry, dir->i_ino); - err = fscrypt_prepare_lookup(dir, dentry, flags); - if (err) - return ERR_PTR(err); - - err = fscrypt_setup_filename(dir, &dentry->d_name, 1, &nm); + err = fscrypt_prepare_lookup(dir, dentry, &nm); + if (err == -ENOENT) + return d_splice_alias(NULL, dentry); if (err) return ERR_PTR(err); diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 39bd2619a3424..c00b764d6b8c9 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -33,6 +33,7 @@ struct fscrypt_name { u32 hash; u32 minor_hash; struct fscrypt_str crypto_buf; + bool is_ciphertext_name; }; #define FSTR_INIT(n, l) { .name = n, .len = l } @@ -233,7 +234,8 @@ extern int __fscrypt_prepare_rename(struct inode *old_dir, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags); -extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry); +extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, + struct fscrypt_name *fname); extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len, unsigned int max_len, struct fscrypt_str *disk_link); @@ -347,7 +349,7 @@ static inline int fscrypt_setup_filename(struct inode *dir, if (IS_ENCRYPTED(dir)) return -EOPNOTSUPP; - memset(fname, 0, sizeof(struct fscrypt_name)); + memset(fname, 0, sizeof(*fname)); fname->usr_fname = iname; fname->disk_name.name = (unsigned char *)iname->name; fname->disk_name.len = iname->len; @@ -434,7 +436,8 @@ static inline int __fscrypt_prepare_rename(struct inode *old_dir, } static inline int __fscrypt_prepare_lookup(struct inode *dir, - struct dentry *dentry) + struct dentry *dentry, + struct fscrypt_name *fname) { return -EOPNOTSUPP; } @@ -555,25 +558,32 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir, * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory * @dir: directory being searched * @dentry: filename being looked up - * @flags: lookup flags + * @fname: (output) the name to use to search the on-disk directory * - * Prepare for ->lookup() in a directory which may be encrypted. Lookups can be - * done with or without the directory's encryption key; without the key, + * Prepare for ->lookup() in a directory which may be encrypted by determining + * the name that will actually be used to search the directory on-disk. Lookups + * can be done with or without the directory's encryption key; without the key, * filenames are presented in encrypted form. Therefore, we'll try to set up * the directory's encryption key, but even without it the lookup can continue. * * This also installs a custom ->d_revalidate() method which will invalidate the * dentry if it was created without the key and the key is later added. * - * Return: 0 on success, -errno if a problem occurred while setting up the - * encryption key + * Return: 0 on success; -ENOENT if key is unavailable but the filename isn't a + * correctly formed encoded ciphertext name, so a negative dentry should be + * created; or another -errno code. */ static inline int fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, - unsigned int flags) + struct fscrypt_name *fname) { if (IS_ENCRYPTED(dir)) - return __fscrypt_prepare_lookup(dir, dentry); + return __fscrypt_prepare_lookup(dir, dentry, fname); + + memset(fname, 0, sizeof(*fname)); + fname->usr_fname = &dentry->d_name; + fname->disk_name.name = (unsigned char *)dentry->d_name.name; + fname->disk_name.len = dentry->d_name.len; return 0; }