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Message-Id: <1456428368-41527-2-git-send-email-jaegeuk@kernel.org>
Date: Thu, 25 Feb 2016 11:25:59 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net, tytso@....edu
Cc: Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 01/10] fs crypto: add basic definitions for per-file encryption
This patch adds definitions for per-file encryption used by ext4 and f2fs.
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
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..d8f57cf 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
+#ifdef 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..b0aed92
--- /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 <linux/key.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/bio.h>
+#include <linux/dcache.h>
+#include <uapi/linux/fs.h>
+
+#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 {
+ char format;
+ char contents_encryption_mode;
+ char filenames_encryption_mode;
+ char flags;
+ char master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
+ char 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;
+ char raw[FS_MAX_KEY_SIZE];
+ __u32 size;
+} __packed;
+
+struct fscrypt_info {
+ char ci_data_mode;
+ char ci_filename_mode;
+ char ci_flags;
+ struct crypto_ablkcipher *ci_ctfm;
+ struct key *ci_keyring_key;
+ char 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 */
+ };
+ char flags; /* Flags */
+ char 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)
+{
+#ifdef 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)
+{
+#ifdef 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..1d26276 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 {
+ char version;
+ char contents_encryption_mode;
+ char filenames_encryption_mode;
+ char flags;
+ char 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
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