/* SPDX-License-Identifier: GPL-2.0 */ /* * fscrypt_private.h * * Copyright (C) 2015, Google, Inc. * * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar. * Heavily modified since then. */ #ifndef _FSCRYPT_PRIVATE_H #define _FSCRYPT_PRIVATE_H #include <linux/fscrypt.h> #include <linux/siphash.h> #include <crypto/hash.h> #include <linux/blk-crypto.h> #define CONST_STRLEN(str) … #define FSCRYPT_FILE_NONCE_SIZE … /* * Minimum size of an fscrypt master key. Note: a longer key will be required * if ciphers with a 256-bit security strength are used. This is just the * absolute minimum, which applies when only 128-bit encryption is used. */ #define FSCRYPT_MIN_KEY_SIZE … #define FSCRYPT_CONTEXT_V1 … #define FSCRYPT_CONTEXT_V2 … /* Keep this in sync with include/uapi/linux/fscrypt.h */ #define FSCRYPT_MODE_MAX … struct fscrypt_context_v1 { … }; struct fscrypt_context_v2 { … }; /* * fscrypt_context - the encryption context of an inode * * This is the on-disk equivalent of an fscrypt_policy, stored alongside each * encrypted file usually in a hidden extended attribute. It contains the * fields from the fscrypt_policy, in order to identify the encryption algorithm * and key with which the file is encrypted. It also contains a nonce that was * randomly generated by fscrypt itself; this is used as KDF input or as a tweak * to cause different files to be encrypted differently. */ fscrypt_context; /* * Return the size expected for the given fscrypt_context based on its version * number, or 0 if the context version is unrecognized. */ static inline int fscrypt_context_size(const union fscrypt_context *ctx) { … } /* Check whether an fscrypt_context has a recognized version number and size */ static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx, int ctx_size) { … } /* Retrieve the context's nonce, assuming the context was already validated */ static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx) { … } fscrypt_policy; /* * Return the size expected for the given fscrypt_policy based on its version * number, or 0 if the policy version is unrecognized. */ static inline int fscrypt_policy_size(const union fscrypt_policy *policy) { … } /* Return the contents encryption mode of a valid encryption policy */ static inline u8 fscrypt_policy_contents_mode(const union fscrypt_policy *policy) { … } /* Return the filenames encryption mode of a valid encryption policy */ static inline u8 fscrypt_policy_fnames_mode(const union fscrypt_policy *policy) { … } /* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */ static inline u8 fscrypt_policy_flags(const union fscrypt_policy *policy) { … } static inline int fscrypt_policy_v2_du_bits(const struct fscrypt_policy_v2 *policy, const struct inode *inode) { … } static inline int fscrypt_policy_du_bits(const union fscrypt_policy *policy, const struct inode *inode) { … } /* * For encrypted symlinks, the ciphertext length is stored at the beginning * of the string in little-endian format. */ struct fscrypt_symlink_data { … } __packed; /** * struct fscrypt_prepared_key - a key prepared for actual encryption/decryption * @tfm: crypto API transform object * @blk_key: key for blk-crypto * * Normally only one of the fields will be non-NULL. */ struct fscrypt_prepared_key { … }; /* * fscrypt_inode_info - the "encryption key" for an inode * * When an encrypted file's key is made available, an instance of this struct is * allocated and stored in ->i_crypt_info. Once created, it remains until the * inode is evicted. */ struct fscrypt_inode_info { … }; fscrypt_direction_t; /* crypto.c */ extern struct kmem_cache *fscrypt_inode_info_cachep; int fscrypt_initialize(struct super_block *sb); int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci, fscrypt_direction_t rw, u64 index, struct page *src_page, struct page *dest_page, unsigned int len, unsigned int offs, gfp_t gfp_flags); struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags); void __printf(3, 4) __cold fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...); #define fscrypt_warn(inode, fmt, ...) … #define fscrypt_err(inode, fmt, ...) … #define FSCRYPT_MAX_IV_SIZE … fscrypt_iv; void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index, const struct fscrypt_inode_info *ci); /* * Return the number of bits used by the maximum file data unit index that is * possible on the given filesystem, using the given log2 data unit size. */ static inline int fscrypt_max_file_dun_bits(const struct super_block *sb, int du_bits) { … } /* fname.c */ bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, u32 orig_len, u32 max_len, u32 *encrypted_len_ret); /* hkdf.c */ struct fscrypt_hkdf { … }; int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key, unsigned int master_key_size); /* * The list of contexts in which fscrypt uses HKDF. These values are used as * the first byte of the HKDF application-specific info string to guarantee that * info strings are never repeated between contexts. This ensures that all HKDF * outputs are unique and cryptographically isolated, i.e. knowledge of one * output doesn't reveal another. */ #define HKDF_CONTEXT_KEY_IDENTIFIER … #define HKDF_CONTEXT_PER_FILE_ENC_KEY … #define HKDF_CONTEXT_DIRECT_KEY … #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY … #define HKDF_CONTEXT_DIRHASH_KEY … #define HKDF_CONTEXT_IV_INO_LBLK_32_KEY … #define HKDF_CONTEXT_INODE_HASH_KEY … int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context, const u8 *info, unsigned int infolen, u8 *okm, unsigned int okmlen); void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf); /* inline_crypt.c */ #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci); static inline bool fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) { … } int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, const u8 *raw_key, const struct fscrypt_inode_info *ci); void fscrypt_destroy_inline_crypt_key(struct super_block *sb, struct fscrypt_prepared_key *prep_key); /* * Check whether the crypto transform or blk-crypto key has been allocated in * @prep_key, depending on which encryption implementation the file will use. */ static inline bool fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, const struct fscrypt_inode_info *ci) { … } #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ static inline int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci) { return 0; } static inline bool fscrypt_using_inline_encryption(const struct fscrypt_inode_info *ci) { return false; } static inline int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, const u8 *raw_key, const struct fscrypt_inode_info *ci) { WARN_ON_ONCE(1); return -EOPNOTSUPP; } static inline void fscrypt_destroy_inline_crypt_key(struct super_block *sb, struct fscrypt_prepared_key *prep_key) { } static inline bool fscrypt_is_key_prepared(struct fscrypt_prepared_key *prep_key, const struct fscrypt_inode_info *ci) { return smp_load_acquire(&prep_key->tfm) != NULL; } #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ /* keyring.c */ /* * fscrypt_master_key_secret - secret key material of an in-use master key */ struct fscrypt_master_key_secret { … } __randomize_layout; /* * fscrypt_master_key - an in-use master key * * This represents a master encryption key which has been added to the * filesystem. There are three high-level states that a key can be in: * * FSCRYPT_KEY_STATUS_PRESENT * Key is fully usable; it can be used to unlock inodes that are encrypted * with it (this includes being able to create new inodes). ->mk_present * indicates whether the key is in this state. ->mk_secret exists, the key * is in the keyring, and ->mk_active_refs > 0 due to ->mk_present. * * FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED * Removal of this key has been initiated, but some inodes that were * unlocked with it are still in-use. Like ABSENT, ->mk_secret is wiped, * and the key can no longer be used to unlock inodes. Unlike ABSENT, the * key is still in the keyring; ->mk_decrypted_inodes is nonempty; and * ->mk_active_refs > 0, being equal to the size of ->mk_decrypted_inodes. * * This state transitions to ABSENT if ->mk_decrypted_inodes becomes empty, * or to PRESENT if FS_IOC_ADD_ENCRYPTION_KEY is called again for this key. * * FSCRYPT_KEY_STATUS_ABSENT * Key is fully removed. The key is no longer in the keyring, * ->mk_decrypted_inodes is empty, ->mk_active_refs == 0, ->mk_secret is * wiped, and the key can no longer be used to unlock inodes. */ struct fscrypt_master_key { … } __randomize_layout; static inline const char *master_key_spec_type( const struct fscrypt_key_specifier *spec) { … } static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec) { … } void fscrypt_put_master_key(struct fscrypt_master_key *mk); void fscrypt_put_master_key_activeref(struct super_block *sb, struct fscrypt_master_key *mk); struct fscrypt_master_key * fscrypt_find_master_key(struct super_block *sb, const struct fscrypt_key_specifier *mk_spec); int fscrypt_get_test_dummy_key_identifier( u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); int fscrypt_add_test_dummy_key(struct super_block *sb, struct fscrypt_key_specifier *key_spec); int fscrypt_verify_key_added(struct super_block *sb, const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]); int __init fscrypt_init_keyring(void); /* keysetup.c */ struct fscrypt_mode { … }; extern struct fscrypt_mode fscrypt_modes[]; int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, const u8 *raw_key, const struct fscrypt_inode_info *ci); void fscrypt_destroy_prepared_key(struct super_block *sb, struct fscrypt_prepared_key *prep_key); int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci, const u8 *raw_key); int fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci, const struct fscrypt_master_key *mk); void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci, const struct fscrypt_master_key *mk); int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported); /** * fscrypt_require_key() - require an inode's encryption key * @inode: the inode we need the key for * * If the inode is encrypted, set up its encryption key if not already done. * Then require that the key be present and return -ENOKEY otherwise. * * No locks are needed, and the key will live as long as the struct inode --- so * it won't go away from under you. * * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code * if a problem occurred while setting up the encryption key. */ static inline int fscrypt_require_key(struct inode *inode) { … } /* keysetup_v1.c */ void fscrypt_put_direct_key(struct fscrypt_direct_key *dk); int fscrypt_setup_v1_file_key(struct fscrypt_inode_info *ci, const u8 *raw_master_key); int fscrypt_setup_v1_file_key_via_subscribed_keyrings( struct fscrypt_inode_info *ci); /* policy.c */ bool fscrypt_policies_equal(const union fscrypt_policy *policy1, const union fscrypt_policy *policy2); int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy, struct fscrypt_key_specifier *key_spec); const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb); bool fscrypt_supported_policy(const union fscrypt_policy *policy_u, const struct inode *inode); int fscrypt_policy_from_context(union fscrypt_policy *policy_u, const union fscrypt_context *ctx_u, int ctx_size); const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir); #endif /* _FSCRYPT_PRIVATE_H */
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