305 lines
8.1 KiB
C
305 lines
8.1 KiB
C
/* 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 <crypto/hash.h>
|
|
|
|
#define CONST_STRLEN(str) (sizeof(str) - 1)
|
|
|
|
#define FS_KEY_DERIVATION_NONCE_SIZE 16
|
|
|
|
#define FSCRYPT_MIN_KEY_SIZE 16
|
|
|
|
/**
|
|
* 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[FSCRYPT_KEY_DESCRIPTOR_SIZE];
|
|
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
|
|
} __packed;
|
|
|
|
#define FS_ENCRYPTION_CONTEXT_FORMAT_V1 1
|
|
|
|
/**
|
|
* 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;
|
|
|
|
/*
|
|
* fscrypt_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_info {
|
|
|
|
/* The actual crypto transform used for encryption and decryption */
|
|
struct crypto_skcipher *ci_ctfm;
|
|
|
|
/*
|
|
* Cipher for ESSIV IV generation. Only set for CBC contents
|
|
* encryption, otherwise is NULL.
|
|
*/
|
|
struct crypto_cipher *ci_essiv_tfm;
|
|
|
|
/*
|
|
* Encryption mode used for this inode. It corresponds to either
|
|
* ci_data_mode or ci_filename_mode, depending on the inode type.
|
|
*/
|
|
struct fscrypt_mode *ci_mode;
|
|
|
|
/* Back-pointer to the inode */
|
|
struct inode *ci_inode;
|
|
|
|
/*
|
|
* The master key with which this inode was unlocked (decrypted). This
|
|
* will be NULL if the master key was found in a process-subscribed
|
|
* keyring rather than in the filesystem-level keyring.
|
|
*/
|
|
struct key *ci_master_key;
|
|
|
|
/*
|
|
* Link in list of inodes that were unlocked with the master key.
|
|
* Only used when ->ci_master_key is set.
|
|
*/
|
|
struct list_head ci_master_key_link;
|
|
|
|
/*
|
|
* If non-NULL, then encryption is done using the master key directly
|
|
* and ci_ctfm will equal ci_direct_key->dk_ctfm.
|
|
*/
|
|
struct fscrypt_direct_key *ci_direct_key;
|
|
|
|
/* fields from the fscrypt_context */
|
|
u8 ci_data_mode;
|
|
u8 ci_filename_mode;
|
|
u8 ci_flags;
|
|
u8 ci_master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
|
|
u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
|
|
};
|
|
|
|
typedef enum {
|
|
FS_DECRYPT = 0,
|
|
FS_ENCRYPT,
|
|
} fscrypt_direction_t;
|
|
|
|
#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
|
|
|
|
static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
|
|
u32 filenames_mode)
|
|
{
|
|
if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
|
|
filenames_mode == FSCRYPT_MODE_AES_128_CTS)
|
|
return true;
|
|
|
|
if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
|
|
filenames_mode == FSCRYPT_MODE_AES_256_CTS)
|
|
return true;
|
|
|
|
if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
|
|
filenames_mode == FSCRYPT_MODE_ADIANTUM)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* crypto.c */
|
|
extern struct kmem_cache *fscrypt_info_cachep;
|
|
extern int fscrypt_initialize(unsigned int cop_flags);
|
|
extern int fscrypt_crypt_block(const struct inode *inode,
|
|
fscrypt_direction_t rw, u64 lblk_num,
|
|
struct page *src_page, struct page *dest_page,
|
|
unsigned int len, unsigned int offs,
|
|
gfp_t gfp_flags);
|
|
extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
|
|
extern const struct dentry_operations fscrypt_d_ops;
|
|
|
|
extern void __printf(3, 4) __cold
|
|
fscrypt_msg(const struct inode *inode, const char *level, const char *fmt, ...);
|
|
|
|
#define fscrypt_warn(inode, fmt, ...) \
|
|
fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
|
|
#define fscrypt_err(inode, fmt, ...) \
|
|
fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
|
|
|
|
#define FSCRYPT_MAX_IV_SIZE 32
|
|
|
|
union fscrypt_iv {
|
|
struct {
|
|
/* logical block number within the file */
|
|
__le64 lblk_num;
|
|
|
|
/* per-file nonce; only set in DIRECT_KEY mode */
|
|
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
|
|
};
|
|
u8 raw[FSCRYPT_MAX_IV_SIZE];
|
|
};
|
|
|
|
void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
|
|
const struct fscrypt_info *ci);
|
|
|
|
/* fname.c */
|
|
extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
|
|
u8 *out, unsigned int olen);
|
|
extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
|
|
u32 orig_len, u32 max_len,
|
|
u32 *encrypted_len_ret);
|
|
|
|
/* keyring.c */
|
|
|
|
/*
|
|
* fscrypt_master_key_secret - secret key material of an in-use master key
|
|
*/
|
|
struct fscrypt_master_key_secret {
|
|
|
|
/* Size of the raw key in bytes */
|
|
u32 size;
|
|
|
|
/* The raw key */
|
|
u8 raw[FSCRYPT_MAX_KEY_SIZE];
|
|
|
|
} __randomize_layout;
|
|
|
|
/*
|
|
* fscrypt_master_key - an in-use master key
|
|
*
|
|
* This represents a master encryption key which has been added to the
|
|
* filesystem and can be used to "unlock" the encrypted files which were
|
|
* encrypted with it.
|
|
*/
|
|
struct fscrypt_master_key {
|
|
|
|
/*
|
|
* The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
|
|
* executed, this is wiped and no new inodes can be unlocked with this
|
|
* key; however, there may still be inodes in ->mk_decrypted_inodes
|
|
* which could not be evicted. As long as some inodes still remain,
|
|
* FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
|
|
* FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
|
|
*
|
|
* Locking: protected by key->sem.
|
|
*/
|
|
struct fscrypt_master_key_secret mk_secret;
|
|
|
|
/* Arbitrary key descriptor which was assigned by userspace */
|
|
struct fscrypt_key_specifier mk_spec;
|
|
|
|
/*
|
|
* Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
|
|
* Once this goes to 0, the master key is removed from ->s_master_keys.
|
|
* The 'struct fscrypt_master_key' will continue to live as long as the
|
|
* 'struct key' whose payload it is, but we won't let this reference
|
|
* count rise again.
|
|
*/
|
|
refcount_t mk_refcount;
|
|
|
|
/*
|
|
* List of inodes that were unlocked using this key. This allows the
|
|
* inodes to be evicted efficiently if the key is removed.
|
|
*/
|
|
struct list_head mk_decrypted_inodes;
|
|
spinlock_t mk_decrypted_inodes_lock;
|
|
|
|
} __randomize_layout;
|
|
|
|
static inline bool
|
|
is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
|
|
{
|
|
/*
|
|
* The READ_ONCE() is only necessary for fscrypt_drop_inode() and
|
|
* fscrypt_key_describe(). These run in atomic context, so they can't
|
|
* take key->sem and thus 'secret' can change concurrently which would
|
|
* be a data race. But they only need to know whether the secret *was*
|
|
* present at the time of check, so READ_ONCE() suffices.
|
|
*/
|
|
return READ_ONCE(secret->size) != 0;
|
|
}
|
|
|
|
static inline const char *master_key_spec_type(
|
|
const struct fscrypt_key_specifier *spec)
|
|
{
|
|
switch (spec->type) {
|
|
case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
|
|
return "descriptor";
|
|
}
|
|
return "[unknown]";
|
|
}
|
|
|
|
static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
|
|
{
|
|
switch (spec->type) {
|
|
case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
|
|
return FSCRYPT_KEY_DESCRIPTOR_SIZE;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
extern struct key *
|
|
fscrypt_find_master_key(struct super_block *sb,
|
|
const struct fscrypt_key_specifier *mk_spec);
|
|
|
|
extern int __init fscrypt_init_keyring(void);
|
|
|
|
/* keysetup.c */
|
|
|
|
struct fscrypt_mode {
|
|
const char *friendly_name;
|
|
const char *cipher_str;
|
|
int keysize;
|
|
int ivsize;
|
|
bool logged_impl_name;
|
|
bool needs_essiv;
|
|
};
|
|
|
|
static inline bool
|
|
fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
|
|
{
|
|
return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
|
|
}
|
|
|
|
extern struct crypto_skcipher *
|
|
fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
|
|
const struct inode *inode);
|
|
|
|
extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
|
|
const u8 *derived_key);
|
|
|
|
/* keysetup_v1.c */
|
|
|
|
extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
|
|
|
|
extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
|
|
const u8 *raw_master_key);
|
|
|
|
extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
|
|
struct fscrypt_info *ci);
|
|
|
|
#endif /* _FSCRYPT_PRIVATE_H */
|