Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756575AbcCBScD (ORCPT ); Wed, 2 Mar 2016 13:32:03 -0500 Received: from mail.kernel.org ([198.145.29.136]:48333 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756244AbcCBSbx (ORCPT ); Wed, 2 Mar 2016 13:31:53 -0500 From: Jaegeuk Kim To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, tytso@mit.edu Cc: Jaegeuk Kim Subject: [PATCH 01/10] fs crypto: add basic definitions for per-file encryption Date: Wed, 2 Mar 2016 10:31:09 -0800 Message-Id: <1456943478-11107-2-git-send-email-jaegeuk@kernel.org> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> References: <1456943478-11107-1-git-send-email-jaegeuk@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8379 Lines: 319 This patch adds definitions for per-file encryption used by ext4 and f2fs. Signed-off-by: Jaegeuk Kim --- include/linux/fs.h | 8 ++ include/linux/fscrypto.h | 239 +++++++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/fs.h | 18 ++++ 3 files changed, 265 insertions(+) create mode 100644 include/linux/fscrypto.h diff --git a/include/linux/fs.h b/include/linux/fs.h index ae68100..28fc121 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -53,6 +53,8 @@ struct swap_info_struct; struct seq_file; struct workqueue_struct; struct iov_iter; +struct fscrypt_info; +struct fscrypt_operations; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -678,6 +680,10 @@ struct inode { struct hlist_head i_fsnotify_marks; #endif +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) + struct fscrypt_info *i_crypt_info; +#endif + void *i_private; /* fs or device private pointer */ }; @@ -1323,6 +1329,8 @@ struct super_block { #endif const struct xattr_handler **s_xattr; + const struct fscrypt_operations *s_cop; + struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */ struct list_head s_mounts; /* list of mounts; _not_ for fs use */ struct block_device *s_bdev; diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h new file mode 100644 index 0000000..4d83f08 --- /dev/null +++ b/include/linux/fscrypto.h @@ -0,0 +1,239 @@ +/* + * General per-file encryption definition + * + * Copyright (C) 2015, Google, Inc. + * + * Written by Michael Halcrow, 2015. + * Modified by Jaegeuk Kim, 2015. + */ + +#ifndef _LINUX_FSCRYPTO_H +#define _LINUX_FSCRYPTO_H + +#include +#include +#include +#include +#include +#include + +#define FS_KEY_DERIVATION_NONCE_SIZE 16 +#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1 + +#define FS_POLICY_FLAGS_PAD_4 0x00 +#define FS_POLICY_FLAGS_PAD_8 0x01 +#define FS_POLICY_FLAGS_PAD_16 0x02 +#define FS_POLICY_FLAGS_PAD_32 0x03 +#define FS_POLICY_FLAGS_PAD_MASK 0x03 +#define FS_POLICY_FLAGS_VALID 0x03 + +/* Encryption algorithms */ +#define FS_ENCRYPTION_MODE_INVALID 0 +#define FS_ENCRYPTION_MODE_AES_256_XTS 1 +#define FS_ENCRYPTION_MODE_AES_256_GCM 2 +#define FS_ENCRYPTION_MODE_AES_256_CBC 3 +#define FS_ENCRYPTION_MODE_AES_256_CTS 4 + +/** + * Encryption context for inode + * + * Protector format: + * 1 byte: Protector format (1 = this version) + * 1 byte: File contents encryption mode + * 1 byte: File names encryption mode + * 1 byte: Flags + * 8 bytes: Master Key descriptor + * 16 bytes: Encryption Key derivation nonce + */ +struct fscrypt_context { + u8 format; + u8 contents_encryption_mode; + u8 filenames_encryption_mode; + u8 flags; + u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; + u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE]; +} __packed; + +/* Encryption parameters */ +#define FS_XTS_TWEAK_SIZE 16 +#define FS_AES_128_ECB_KEY_SIZE 16 +#define FS_AES_256_GCM_KEY_SIZE 32 +#define FS_AES_256_CBC_KEY_SIZE 32 +#define FS_AES_256_CTS_KEY_SIZE 32 +#define FS_AES_256_XTS_KEY_SIZE 64 +#define FS_MAX_KEY_SIZE 64 + +#define FS_KEY_DESC_PREFIX "fscrypt:" +#define FS_KEY_DESC_PREFIX_SIZE 8 + +/* This is passed in from userspace into the kernel keyring */ +struct fscrypt_key { + u32 mode; + u8 raw[FS_MAX_KEY_SIZE]; + u32 size; +} __packed; + +struct fscrypt_info { + u8 ci_data_mode; + u8 ci_filename_mode; + u8 ci_flags; + struct crypto_ablkcipher *ci_ctfm; + struct key *ci_keyring_key; + u8 ci_master_key[FS_KEY_DESCRIPTOR_SIZE]; +}; + +#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001 +#define FS_WRITE_PATH_FL 0x00000002 + +struct fscrypt_ctx { + union { + struct { + struct page *bounce_page; /* Ciphertext page */ + struct page *control_page; /* Original page */ + } w; + struct { + struct bio *bio; + struct work_struct work; + } r; + struct list_head free_list; /* Free list */ + }; + u8 flags; /* Flags */ + u8 mode; /* Encryption mode for tfm */ +}; + +struct fscrypt_completion_result { + struct completion completion; + int res; +}; + +#define DECLARE_FS_COMPLETION_RESULT(ecr) \ + struct fscrypt_completion_result ecr = { \ + COMPLETION_INITIALIZER((ecr).completion), 0 } + +static inline int fscrypt_key_size(int mode) +{ + switch (mode) { + case FS_ENCRYPTION_MODE_AES_256_XTS: + return FS_AES_256_XTS_KEY_SIZE; + case FS_ENCRYPTION_MODE_AES_256_GCM: + return FS_AES_256_GCM_KEY_SIZE; + case FS_ENCRYPTION_MODE_AES_256_CBC: + return FS_AES_256_CBC_KEY_SIZE; + case FS_ENCRYPTION_MODE_AES_256_CTS: + return FS_AES_256_CTS_KEY_SIZE; + default: + BUG(); + } + return 0; +} + +#define FS_FNAME_NUM_SCATTER_ENTRIES 4 +#define FS_CRYPTO_BLOCK_SIZE 16 +#define FS_FNAME_CRYPTO_DIGEST_SIZE 32 + +/** + * For encrypted symlinks, the ciphertext length is stored at the beginning + * of the string in little-endian format. + */ +struct fscrypt_symlink_data { + __le16 len; + char encrypted_path[1]; +} __packed; + +/** + * This function is used to calculate the disk space required to + * store a filename of length l in encrypted symlink format. + */ +static inline u32 fscrypt_symlink_data_len(u32 l) +{ + if (l < FS_CRYPTO_BLOCK_SIZE) + l = FS_CRYPTO_BLOCK_SIZE; + return (l + sizeof(struct fscrypt_symlink_data) - 1); +} + +struct fscrypt_str { + unsigned char *name; + u32 len; +}; + +struct fscrypt_name { + const struct qstr *usr_fname; + struct fscrypt_str disk_name; + u32 hash; + u32 minor_hash; + struct fscrypt_str crypto_buf; +}; + +#define FSTR_INIT(n, l) { .name = n, .len = l } +#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len) +#define fname_name(p) ((p)->disk_name.name) +#define fname_len(p) ((p)->disk_name.len) + +/* + * crypto opertions for filesystems + */ +struct fscrypt_operations { + int (*get_context)(struct inode *, void *, size_t); + int (*prepare_context)(struct inode *); + int (*set_context)(struct inode *, const void *, size_t, void *); + int (*dummy_context)(struct inode *); + bool (*is_encrypted)(struct inode *); + bool (*empty_dir)(struct inode *); + unsigned (*max_namelen)(struct inode *); +}; + +static inline bool fscrypt_dummy_context_enabled(struct inode *inode) +{ + if (inode->i_sb->s_cop->dummy_context && + inode->i_sb->s_cop->dummy_context(inode)) + return true; + return false; +} + +static inline bool fscrypt_valid_contents_enc_mode(u32 mode) +{ + return (mode == FS_ENCRYPTION_MODE_AES_256_XTS); +} + +static inline bool fscrypt_valid_filenames_enc_mode(u32 mode) +{ + return (mode == FS_ENCRYPTION_MODE_AES_256_CTS); +} + +static inline u32 fscrypt_validate_encryption_key_size(u32 mode, u32 size) +{ + if (size == fscrypt_key_size(mode)) + return size; + return 0; +} + +static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) +{ + if (str->len == 1 && str->name[0] == '.') + return true; + + if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.') + return true; + + return false; +} + +static inline struct page *fscrypt_control_page(struct page *page) +{ +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) + return ((struct fscrypt_ctx *)page_private(page))->w.control_page; +#else + WARN_ON_ONCE(1); + return ERR_PTR(-EINVAL); +#endif +} + +static inline int fscrypt_has_encryption_key(struct inode *inode) +{ +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) + return (inode->i_crypt_info != NULL); +#else + return 0; +#endif +} +#endif /* _LINUX_FSCRYPTO_H */ diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 149bec8..fd8b77e 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -247,6 +247,24 @@ struct fsxattr { #define FS_IOC_FSSETXATTR _IOW ('X', 32, struct fsxattr) /* + * File system encryption support + */ +/* Policy provided via an ioctl on the topmost directory */ +#define FS_KEY_DESCRIPTOR_SIZE 8 + +struct fscrypt_policy { + u8 version; + u8 contents_encryption_mode; + u8 filenames_encryption_mode; + u8 flags; + u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; +} __packed; + +#define FS_IOC_SET_ENCRYPTION_POLICY _IOR('f', 19, struct fscrypt_policy) +#define FS_IOC_GET_ENCRYPTION_PWSALT _IOW('f', 20, __u8[16]) +#define FS_IOC_GET_ENCRYPTION_POLICY _IOW('f', 21, struct fscrypt_policy) + +/* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) * * Note: for historical reasons, these flags were originally used and -- 2.6.3