254 lines
6.3 KiB
C
254 lines
6.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* fscrypt_private.h
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*
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* Copyright (C) 2015, Google, Inc.
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*
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* Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
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* Heavily modified since then.
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*/
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#ifndef _FSCRYPT_PRIVATE_H
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#define _FSCRYPT_PRIVATE_H
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#include <linux/fscrypt.h>
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#include <crypto/hash.h>
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#define CONST_STRLEN(str) (sizeof(str) - 1)
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#define FS_KEY_DERIVATION_NONCE_SIZE 16
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#define FSCRYPT_MIN_KEY_SIZE 16
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/**
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* Encryption context for inode
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*
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* Protector format:
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* 1 byte: Protector format (1 = this version)
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* 1 byte: File contents encryption mode
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* 1 byte: File names encryption mode
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* 1 byte: Flags
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* 8 bytes: Master Key descriptor
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* 16 bytes: Encryption Key derivation nonce
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*/
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struct fscrypt_context {
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u8 format;
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u8 contents_encryption_mode;
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u8 filenames_encryption_mode;
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u8 flags;
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u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
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u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
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} __packed;
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#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
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/**
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* For encrypted symlinks, the ciphertext length is stored at the beginning
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* of the string in little-endian format.
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*/
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struct fscrypt_symlink_data {
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__le16 len;
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char encrypted_path[1];
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} __packed;
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/*
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* fscrypt_info - the "encryption key" for an inode
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*
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* When an encrypted file's key is made available, an instance of this struct is
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* allocated and stored in ->i_crypt_info. Once created, it remains until the
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* inode is evicted.
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*/
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struct fscrypt_info {
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/* The actual crypto transform used for encryption and decryption */
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struct crypto_skcipher *ci_ctfm;
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/*
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* Cipher for ESSIV IV generation. Only set for CBC contents
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* encryption, otherwise is NULL.
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*/
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struct crypto_cipher *ci_essiv_tfm;
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/*
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* Encryption mode used for this inode. It corresponds to either
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* ci_data_mode or ci_filename_mode, depending on the inode type.
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*/
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struct fscrypt_mode *ci_mode;
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/* Back-pointer to the inode */
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struct inode *ci_inode;
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/*
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* If non-NULL, then encryption is done using the master key directly
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* and ci_ctfm will equal ci_direct_key->dk_ctfm.
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*/
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struct fscrypt_direct_key *ci_direct_key;
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/* fields from the fscrypt_context */
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u8 ci_data_mode;
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u8 ci_filename_mode;
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u8 ci_flags;
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u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
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u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
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};
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typedef enum {
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FS_DECRYPT = 0,
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FS_ENCRYPT,
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} fscrypt_direction_t;
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#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
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static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
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u32 filenames_mode)
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{
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if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
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filenames_mode == FSCRYPT_MODE_AES_128_CTS)
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return true;
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if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
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filenames_mode == FSCRYPT_MODE_AES_256_CTS)
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return true;
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if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
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filenames_mode == FSCRYPT_MODE_ADIANTUM)
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return true;
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return false;
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}
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/* crypto.c */
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extern struct kmem_cache *fscrypt_info_cachep;
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extern int fscrypt_initialize(unsigned int cop_flags);
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extern int fscrypt_crypt_block(const struct inode *inode,
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fscrypt_direction_t rw, u64 lblk_num,
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struct page *src_page, struct page *dest_page,
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unsigned int len, unsigned int offs,
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gfp_t gfp_flags);
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extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
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extern const struct dentry_operations fscrypt_d_ops;
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extern void __printf(3, 4) __cold
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fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
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#define fscrypt_warn(inode, fmt, ...) \
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fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
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#define fscrypt_err(inode, fmt, ...) \
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fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
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#define FSCRYPT_MAX_IV_SIZE 32
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union fscrypt_iv {
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struct {
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/* logical block number within the file */
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__le64 lblk_num;
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/* per-file nonce; only set in DIRECT_KEY mode */
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u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
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};
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u8 raw[FSCRYPT_MAX_IV_SIZE];
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};
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void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
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const struct fscrypt_info *ci);
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/* fname.c */
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extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
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u8 *out, unsigned int olen);
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extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
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u32 orig_len, u32 max_len,
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u32 *encrypted_len_ret);
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/* keyring.c */
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/*
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* fscrypt_master_key_secret - secret key material of an in-use master key
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*/
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struct fscrypt_master_key_secret {
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/* Size of the raw key in bytes */
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u32 size;
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/* The raw key */
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u8 raw[FSCRYPT_MAX_KEY_SIZE];
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} __randomize_layout;
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/*
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* fscrypt_master_key - an in-use master key
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*
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* This represents a master encryption key which has been added to the
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* filesystem and can be used to "unlock" the encrypted files which were
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* encrypted with it.
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*/
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struct fscrypt_master_key {
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/* The secret key material */
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struct fscrypt_master_key_secret mk_secret;
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/* Arbitrary key descriptor which was assigned by userspace */
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struct fscrypt_key_specifier mk_spec;
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} __randomize_layout;
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static inline const char *master_key_spec_type(
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const struct fscrypt_key_specifier *spec)
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{
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switch (spec->type) {
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case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
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return "descriptor";
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}
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return "[unknown]";
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}
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static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
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{
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switch (spec->type) {
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case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
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return FSCRYPT_KEY_DESCRIPTOR_SIZE;
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}
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return 0;
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}
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extern struct key *
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fscrypt_find_master_key(struct super_block *sb,
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const struct fscrypt_key_specifier *mk_spec);
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extern int __init fscrypt_init_keyring(void);
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/* keysetup.c */
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struct fscrypt_mode {
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const char *friendly_name;
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const char *cipher_str;
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int keysize;
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int ivsize;
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bool logged_impl_name;
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bool needs_essiv;
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};
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static inline bool
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fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
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{
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return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
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}
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extern struct crypto_skcipher *
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fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
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const struct inode *inode);
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extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
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const u8 *derived_key);
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/* keysetup_v1.c */
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extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
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extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
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const u8 *raw_master_key);
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extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
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struct fscrypt_info *ci);
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#endif /* _FSCRYPT_PRIVATE_H */
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