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Ts'o" , Jaegeuk Kim , Ilya Dryomov , linux-fscrypt@vger.kernel.org, ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, =?utf-8?q?Lu?= =?utf-8?q?=C3=ADs_Henriques?= Subject: [PATCH v3 1/3] fscrypt: new helper function - fscrypt_prepare_lookup_partial() Date: Thu, 16 Mar 2023 18:14:11 +0000 Message-Id: <20230316181413.26916-2-lhenriques@suse.de> In-Reply-To: <20230316181413.26916-1-lhenriques@suse.de> References: <20230316181413.26916-1-lhenriques@suse.de> MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1760549641754308869?= X-GMAIL-MSGID: =?utf-8?q?1760549641754308869?= This patch introduces a new helper function which can be used both in lookups and in atomic_open operations by filesystems that want to handle filename encryption and no-key dentries themselves. The reason for this function to be used in atomic open is that this operation can act as a lookup if handed a dentry that is negative. And in this case we may need to set DCACHE_NOKEY_NAME. Signed-off-by: Luís Henriques --- fs/crypto/hooks.c | 37 +++++++++++++++++++++++++++++++++++++ include/linux/fscrypt.h | 7 +++++++ 2 files changed, 44 insertions(+) diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c index 7b8c5a1104b5..4bebdeaadc52 100644 --- a/fs/crypto/hooks.c +++ b/fs/crypto/hooks.c @@ -117,6 +117,43 @@ int __fscrypt_prepare_readdir(struct inode *dir) } EXPORT_SYMBOL_GPL(__fscrypt_prepare_readdir); +/** + * fscrypt_prepare_lookup_partial() - prepare lookup without filenames handling + * @dir: inode of parent directory + * @dentry: dentry to lookup + * + * This function can be used by filesystems that want/need to handle filename + * encryption and no-key name encoding themselves, and thus aren't able to use + * function fscrypt_prepare_lookup(). + + * This helper can be called from lookup and atomic open operations. It will + * try to set the encryption info on the in @dir if the key is available and, if + * it isn't, it will also set the @dentry as non-key. + * + * The reason it needs to get the encryption info before checking if the + * directory has the encryption key is because the key may be available but the + * encryption info isn't yet set (maybe due to a drop_caches). The regular open + * path will use fscrypt_prepare_lookup(), but if a filesystem can't use this + * function (because it handles the filename encryption and no-key dentries) the + * atomic_open requires a different approach. + * + * Return: 0 on success, or an error code if fscrypt_get_encryption_info() + * fails. + */ +int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry) +{ + int err = fscrypt_get_encryption_info(dir, true); + + if (!err && !fscrypt_has_encryption_key(dir)) { + spin_lock(&dentry->d_lock); + dentry->d_flags |= DCACHE_NOKEY_NAME; + spin_unlock(&dentry->d_lock); + } + + return err; +} +EXPORT_SYMBOL_GPL(fscrypt_prepare_lookup_partial); + int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr) { if (attr->ia_valid & ATTR_SIZE) diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 4f5f8a651213..d9a94cd56cda 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -362,6 +362,7 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry, int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry, struct fscrypt_name *fname); int __fscrypt_prepare_readdir(struct inode *dir); +int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry); int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr); int fscrypt_prepare_setflags(struct inode *inode, unsigned int oldflags, unsigned int flags); @@ -688,6 +689,12 @@ static inline int __fscrypt_prepare_readdir(struct inode *dir) return -EOPNOTSUPP; } +static inline int fscrypt_prepare_lookup_partial(struct inode *dir, + struct dentry *dentry) +{ + return -EOPNOTSUPP; +} + static inline int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr) {