Viewing: llcrypt_private.h
/* SPDX-License-Identifier: GPL-2.0 */
/*
* llcrypt_private.h
*
* Copyright (C) 2015, Google, Inc.
*
* Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
* Heavily modified since then.
*/
/*
* Linux commit 219d54332a09
* tags/v5.4
*/
#ifndef _LLCRYPT_PRIVATE_H
#define _LLCRYPT_PRIVATE_H
#include <lustre_compat/linux/llcrypt.h>
#include <lustre_compat/linux/mm.h>
#include <linux/libcfs/libcfs_debug.h>
#include <linux/libcfs/libcfs_private.h>
#include <crypto/hash.h>
#include <lustre_disk.h>
#include <uapi/linux/lustre/lgss.h>
#ifndef CRYPTO_TFM_REQ_FORBID_WEAK_KEYS
#define CRYPTO_TFM_REQ_FORBID_WEAK_KEYS CRYPTO_TFM_REQ_WEAK_KEY
#endif
#define llcrypt_info(inode) ((struct llcrypt_info *)(inode)->i_private)
#define llcrypt_info_nocast(inode) ((inode)->i_private)
#define CONST_STRLEN(str) (sizeof(str) - 1)
#define FS_KEY_DERIVATION_NONCE_SIZE 16
#define LLCRYPT_MIN_KEY_SIZE 16
#define LLCRYPT_CONTEXT_V1 1
#define LLCRYPT_CONTEXT_V2 2
struct llcrypt_context_v1 {
u8 version; /* LLCRYPT_CONTEXT_V1 */
u8 contents_encryption_mode;
u8 filenames_encryption_mode;
u8 flags;
u8 master_key_descriptor[LLCRYPT_KEY_DESCRIPTOR_SIZE];
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};
struct llcrypt_context_v2 {
u8 version; /* LLCRYPT_CONTEXT_V2 */
u8 contents_encryption_mode;
u8 filenames_encryption_mode;
u8 flags;
u8 __reserved[4];
u8 master_key_identifier[LLCRYPT_KEY_IDENTIFIER_SIZE];
u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};
/**
* llcrypt_context - the encryption context of an inode
*
* This is the on-disk equivalent of an llcrypt_policy, stored alongside each
* encrypted file usually in a hidden extended attribute. It contains the
* fields from the llcrypt_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 llcrypt itself; this is used as KDF input or as a tweak
* to cause different files to be encrypted differently.
*/
union llcrypt_context {
u8 version;
struct llcrypt_context_v1 v1;
struct llcrypt_context_v2 v2;
};
/*
* Return the size expected for the given llcrypt_context based on its version
* number, or 0 if the context version is unrecognized.
*/
static inline int llcrypt_context_size(const union llcrypt_context *ctx)
{
switch (ctx->version) {
case LLCRYPT_CONTEXT_V1:
BUILD_BUG_ON(sizeof(ctx->v1) != 28);
return sizeof(ctx->v1);
case LLCRYPT_CONTEXT_V2:
BUILD_BUG_ON(sizeof(ctx->v2) != 40);
return sizeof(ctx->v2);
}
return 0;
}
#undef llcrypt_policy
union llcrypt_policy {
u8 version;
struct llcrypt_policy_v1 v1;
struct llcrypt_policy_v2 v2;
};
/*
* Return the size expected for the given llcrypt_policy based on its version
* number, or 0 if the policy version is unrecognized.
*/
static inline int llcrypt_policy_size(const union llcrypt_policy *policy)
{
switch (policy->version) {
case LLCRYPT_POLICY_V1:
return sizeof(policy->v1);
case LLCRYPT_POLICY_V2:
return sizeof(policy->v2);
}
return 0;
}
/* Return the contents encryption mode of a valid encryption policy */
static inline u8
llcrypt_policy_contents_mode(const union llcrypt_policy *policy)
{
switch (policy->version) {
case LLCRYPT_POLICY_V1:
return policy->v1.contents_encryption_mode;
case LLCRYPT_POLICY_V2:
return policy->v2.contents_encryption_mode;
}
BUG();
}
/* Return the filenames encryption mode of a valid encryption policy */
static inline u8
llcrypt_policy_fnames_mode(const union llcrypt_policy *policy)
{
switch (policy->version) {
case LLCRYPT_POLICY_V1:
return policy->v1.filenames_encryption_mode;
case LLCRYPT_POLICY_V2:
return policy->v2.filenames_encryption_mode;
}
BUG();
}
/* Return the flags (LLCRYPT_POLICY_FLAG*) of a valid encryption policy */
static inline u8
llcrypt_policy_flags(const union llcrypt_policy *policy)
{
switch (policy->version) {
case LLCRYPT_POLICY_V1:
return policy->v1.flags;
case LLCRYPT_POLICY_V2:
return policy->v2.flags;
}
BUG();
}
static inline bool
llcrypt_is_direct_key_policy(const union llcrypt_policy *policy)
{
return llcrypt_policy_flags(policy) & LLCRYPT_POLICY_FLAG_DIRECT_KEY;
}
/**
* For encrypted symlinks, the ciphertext length is stored at the beginning
* of the string in little-endian format.
*/
struct llcrypt_symlink_data {
__le16 len;
char encrypted_path[];
} __packed;
/*
* llcrypt_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 '(struct llcrypt_info *)inode->i_private'.
* Once created, it remains until the inode is evicted.
*/
struct llcrypt_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 the
* contents or filenames encryption mode, depending on the inode type.
*/
struct llcrypt_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 llcrypt_direct_key *ci_direct_key;
/* The encryption policy used by this inode */
union llcrypt_policy ci_policy;
/* This inode's nonce, copied from the llcrypt_context */
u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};
typedef enum {
FS_DECRYPT = 0,
FS_ENCRYPT,
} llcrypt_direction_t;
#define FS_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
static inline bool llcrypt_valid_enc_modes(u32 contents_mode,
u32 filenames_mode)
{
if (contents_mode == LLCRYPT_MODE_AES_128_CBC &&
(filenames_mode == LLCRYPT_MODE_AES_128_CTS ||
filenames_mode == LLCRYPT_MODE_NULL))
return true;
if (contents_mode == LLCRYPT_MODE_AES_256_XTS &&
(filenames_mode == LLCRYPT_MODE_AES_256_CTS ||
filenames_mode == LLCRYPT_MODE_NULL))
return true;
if (contents_mode == LLCRYPT_MODE_ADIANTUM &&
(filenames_mode == LLCRYPT_MODE_ADIANTUM ||
filenames_mode == LLCRYPT_MODE_NULL))
return true;
return false;
}
/* crypto.c */
enum llcrypt_crypto_engine_type {
LLCRYPT_ENGINE_INVALID = 0,
LLCRYPT_ENGINE_SYSTEM_DEFAULT = 1,
LLCRYPT_ENGINE_AES_NI = 2,
};
extern enum llcrypt_crypto_engine_type llcrypt_crypto_engine;
extern struct kmem_cache *llcrypt_info_cachep;
extern int llcrypt_initialize(unsigned int cop_flags);
extern int llcrypt_crypt_block(const struct inode *inode,
llcrypt_direction_t rw, u64 lblk_num,
struct folio *src_page, s32 spg,
struct folio *dest_page, s32 dpg,
size_t len, size_t offs,
gfp_t gfp_flags);
extern struct folio *llcrypt_alloc_bounce(gfp_t gfp_flags);
extern const struct dentry_operations llcrypt_d_ops;
extern void __printf(3, 4) __cold
llcrypt_msg(const struct inode *inode, int mask, const char *fmt, ...);
#define llcrypt_warn(inode, fmt, ...) \
llcrypt_msg((inode), D_SEC, fmt, ##__VA_ARGS__)
#define llcrypt_err(inode, fmt, ...) \
llcrypt_msg((inode), D_ERROR, fmt, ##__VA_ARGS__)
#define LLCRYPT_MAX_IV_SIZE 32
union llcrypt_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[LLCRYPT_MAX_IV_SIZE];
};
void llcrypt_generate_iv(union llcrypt_iv *iv, u64 lblk_num,
const struct llcrypt_info *ci);
/* fname.c */
extern int fname_encrypt(struct inode *inode, const struct qstr *iname,
u8 *out, unsigned int olen);
extern bool llcrypt_fname_encrypted_size(const struct inode *inode,
u32 orig_len, u32 max_len,
u32 *encrypted_len_ret);
/* hkdf.c */
struct llcrypt_hkdf {
struct crypto_shash *hmac_tfm;
};
extern int llcrypt_init_hkdf(struct llcrypt_hkdf *hkdf, const u8 *master_key,
unsigned int master_key_size);
/*
* The list of contexts in which llcrypt 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 1
#define HKDF_CONTEXT_PER_FILE_KEY 2
#define HKDF_CONTEXT_PER_MODE_KEY 3
extern int llcrypt_hkdf_expand(struct llcrypt_hkdf *hkdf, u8 context,
const u8 *info, unsigned int infolen,
u8 *okm, unsigned int okmlen);
extern void llcrypt_destroy_hkdf(struct llcrypt_hkdf *hkdf);
/* keyring.c */
/*
* llcrypt_master_key_secret - secret key material of an in-use master key
*/
struct llcrypt_master_key_secret {
/*
* For v2 policy keys: HKDF context keyed by this master key.
* For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
*/
struct llcrypt_hkdf hkdf;
/* Size of the raw key in bytes. Set even if ->raw isn't set. */
u32 size;
/* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
u8 raw[LLCRYPT_MAX_KEY_SIZE];
} __randomize_layout;
/*
* llcrypt_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 llcrypt_master_key {
/*
* The secret key material. After LL_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,
* LL_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
* LL_IOC_ADD_ENCRYPTION_KEY can add the secret again.
*
* Locking: protected by key->sem (outer) and mk_secret_sem (inner).
* The reason for two locks is that key->sem also protects modifying
* mk_users, which ranks it above the semaphore for the keyring key
* type, which is in turn above page faults (via keyring_read). But
* sometimes filesystems call llcrypt_get_encryption_info() from within
* a transaction, which ranks it below page faults. So we need a
* separate lock which protects mk_secret but not also mk_users.
*/
struct llcrypt_master_key_secret mk_secret;
struct rw_semaphore mk_secret_sem;
/*
* For v1 policy keys: an arbitrary key descriptor which was assigned by
* userspace (->descriptor).
*
* For v2 policy keys: a cryptographic hash of this key (->identifier).
*/
struct llcrypt_key_specifier mk_spec;
/*
* Keyring which contains a key of type 'key_type_llcrypt_user' for each
* user who has added this key. Normally each key will be added by just
* one user, but it's possible that multiple users share a key, and in
* that case we need to keep track of those users so that one user can't
* remove the key before the others want it removed too.
*
* This is NULL for v1 policy keys; those can only be added by root.
*
* Locking: in addition to this keyrings own semaphore, this is
* protected by the master key's key->sem, so we can do atomic
* search+insert. It can also be searched without taking any locks, but
* in that case the returned key may have already been removed.
*/
struct key *mk_users;
/*
* Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
* Once this goes to 0, the master key is removed from ->lsi_master_keys.
* The 'struct llcrypt_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;
/* Per-mode tfms for DIRECT_KEY policies, allocated on-demand */
struct crypto_skcipher *mk_mode_keys[__LLCRYPT_MODE_MAX + 1];
} __randomize_layout;
static inline bool
is_master_key_secret_present(const struct llcrypt_master_key_secret *secret)
{
/*
* The READ_ONCE() is only necessary for llcrypt_drop_inode() and
* llcrypt_key_describe(). These run in atomic context, so they can't
* take ->mk_secret_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 llcrypt_key_specifier *spec)
{
switch (spec->type) {
case LLCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
return "descriptor";
case LLCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
return "identifier";
}
return "[unknown]";
}
static inline int master_key_spec_len(const struct llcrypt_key_specifier *spec)
{
switch (spec->type) {
case LLCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
return LLCRYPT_KEY_DESCRIPTOR_SIZE;
case LLCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
return LLCRYPT_KEY_IDENTIFIER_SIZE;
}
return 0;
}
extern struct key *
llcrypt_find_master_key(struct super_block *sb,
const struct llcrypt_key_specifier *mk_spec);
extern int llcrypt_verify_key_added(struct super_block *sb,
const u8 identifier[LLCRYPT_KEY_IDENTIFIER_SIZE]);
extern int __init llcrypt_init_keyring(void);
extern void __exit llcrypt_exit_keyring(void);
/* keysetup.c */
struct llcrypt_mode {
const char *friendly_name;
const char *cipher_str;
const char *engine_aesni_str;
int keysize;
int ivsize;
bool logged_impl_name;
bool needs_essiv;
};
static inline bool
llcrypt_mode_supports_direct_key(const struct llcrypt_mode *mode)
{
return mode->ivsize >= offsetofend(union llcrypt_iv, nonce);
}
extern struct crypto_skcipher *
llcrypt_allocate_skcipher(struct llcrypt_mode *mode, const u8 *raw_key,
const struct inode *inode);
extern int llcrypt_set_derived_key(struct llcrypt_info *ci,
const u8 *derived_key);
/* keysetup_v1.c */
extern void llcrypt_put_direct_key(struct llcrypt_direct_key *dk);
extern int llcrypt_setup_v1_file_key(struct llcrypt_info *ci,
const u8 *raw_master_key);
extern int llcrypt_setup_v1_file_key_via_subscribed_keyrings(
struct llcrypt_info *ci);
/* policy.c */
extern bool llcrypt_policies_equal(const union llcrypt_policy *policy1,
const union llcrypt_policy *policy2);
extern bool llcrypt_supported_policy(const union llcrypt_policy *policy_u,
const struct inode *inode);
extern int llcrypt_policy_from_context(union llcrypt_policy *policy_u,
const union llcrypt_context *ctx_u,
int ctx_size);
#endif /* _LLCRYPT_PRIVATE_H */
