[linux-block.git] / fs / crypto / fscrypt_private.h

/* 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

#define FSCRYPT_CONTEXT_V1	1
#define FSCRYPT_CONTEXT_V2	2

struct fscrypt_context_v1 {
	u8 version; /* FSCRYPT_CONTEXT_V1 */
	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];
};

struct fscrypt_context_v2 {
	u8 version; /* FSCRYPT_CONTEXT_V2 */
	u8 contents_encryption_mode;
	u8 filenames_encryption_mode;
	u8 flags;
	u8 __reserved[4];
	u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};

/**
 * 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.
 */
union fscrypt_context {
	u8 version;
	struct fscrypt_context_v1 v1;
	struct fscrypt_context_v2 v2;
};

/*
 * 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)
{
	switch (ctx->version) {
	case FSCRYPT_CONTEXT_V1:
		BUILD_BUG_ON(sizeof(ctx->v1) != 28);
		return sizeof(ctx->v1);
	case FSCRYPT_CONTEXT_V2:
		BUILD_BUG_ON(sizeof(ctx->v2) != 40);
		return sizeof(ctx->v2);
	}
	return 0;
}

#undef fscrypt_policy
union fscrypt_policy {
	u8 version;
	struct fscrypt_policy_v1 v1;
	struct fscrypt_policy_v2 v2;
};

/*
 * 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)
{
	switch (policy->version) {
	case FSCRYPT_POLICY_V1:
		return sizeof(policy->v1);
	case FSCRYPT_POLICY_V2:
		return sizeof(policy->v2);
	}
	return 0;
}

/* Return the contents encryption mode of a valid encryption policy */
static inline u8
fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
{
	switch (policy->version) {
	case FSCRYPT_POLICY_V1:
		return policy->v1.contents_encryption_mode;
	case FSCRYPT_POLICY_V2:
		return policy->v2.contents_encryption_mode;
	}
	BUG();
}

/* Return the filenames encryption mode of a valid encryption policy */
static inline u8
fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
{
	switch (policy->version) {
	case FSCRYPT_POLICY_V1:
		return policy->v1.filenames_encryption_mode;
	case FSCRYPT_POLICY_V2:
		return policy->v2.filenames_encryption_mode;
	}
	BUG();
}

/* Return the flags (FSCRYPT_POLICY_FLAG*) of a valid encryption policy */
static inline u8
fscrypt_policy_flags(const union fscrypt_policy *policy)
{
	switch (policy->version) {
	case FSCRYPT_POLICY_V1:
		return policy->v1.flags;
	case FSCRYPT_POLICY_V2:
		return policy->v2.flags;
	}
	BUG();
}

static inline bool
fscrypt_is_direct_key_policy(const union fscrypt_policy *policy)
{
	return fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAG_DIRECT_KEY;
}

/**
 * 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;

	/* True if the key should be freed when this fscrypt_info is freed */
	bool ci_owns_key;

	/*
	 * Encryption mode used for this inode.  It corresponds to either the
	 * contents or filenames encryption 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;

	/* The encryption policy used by this inode */
	union fscrypt_policy ci_policy;

	/* This inode's nonce, copied from the fscrypt_context */
	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
};

typedef enum {
	FS_DECRYPT = 0,
	FS_ENCRYPT,
} fscrypt_direction_t;

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);

/* hkdf.c */

struct fscrypt_hkdf {
	struct crypto_shash *hmac_tfm;
};

extern 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	1
#define HKDF_CONTEXT_PER_FILE_KEY	2
#define HKDF_CONTEXT_DIRECT_KEY		3
#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4

extern int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context,
			       const u8 *info, unsigned int infolen,
			       u8 *okm, unsigned int okmlen);

extern void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);

/* keyring.c */

/*
 * fscrypt_master_key_secret - secret key material of an in-use master key
 */
struct fscrypt_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 fscrypt_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[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 (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 fscrypt_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 fscrypt_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 fscrypt_key_specifier		mk_spec;

	/*
	 * Keyring which contains a key of type 'key_type_fscrypt_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 ->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;

	/* Crypto API transforms for DIRECT_KEY policies, allocated on-demand */
	struct crypto_skcipher	*mk_direct_tfms[__FSCRYPT_MODE_MAX + 1];

	/*
	 * Crypto API transforms for filesystem-layer implementation of
	 * IV_INO_LBLK_64 policies, allocated on-demand.
	 */
	struct crypto_skcipher	*mk_iv_ino_lblk_64_tfms[__FSCRYPT_MODE_MAX + 1];

} __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 ->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 fscrypt_key_specifier *spec)
{
	switch (spec->type) {
	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
		return "descriptor";
	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
		return "identifier";
	}
	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;
	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
		return FSCRYPT_KEY_IDENTIFIER_SIZE;
	}
	return 0;
}

extern struct key *
fscrypt_find_master_key(struct super_block *sb,
			const struct fscrypt_key_specifier *mk_spec);

extern int fscrypt_verify_key_added(struct super_block *sb,
				    const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);

extern int __init fscrypt_init_keyring(void);

/* keysetup.c */

struct fscrypt_mode {
	const char *friendly_name;
	const char *cipher_str;
	int keysize;
	int ivsize;
	int logged_impl_name;
};

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);
/* policy.c */

extern bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
				   const union fscrypt_policy *policy2);
extern bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
				     const struct inode *inode);
extern int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
				       const union fscrypt_context *ctx_u,
				       int ctx_size);

#endif /* _FSCRYPT_PRIVATE_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
3325bea5 TT	2	/*
	3	* fscrypt_private.h
	4	*
	5	* Copyright (C) 2015, Google, Inc.
	6	*
3ec4f2a6 EB	7	* Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar.
3ec4f2a6 EB	8	* Heavily modified since then.
3325bea5 TT	9	*/
	10
	11	#ifndef _FSCRYPT_PRIVATE_H
	12	#define _FSCRYPT_PRIVATE_H
	13
734f0d24	14	#include <linux/fscrypt.h>
b7e7cf7a	15	#include <crypto/hash.h>
3325bea5	16
22d94f49 EB	17	#define CONST_STRLEN(str) (sizeof(str) - 1)
22d94f49 EB	18
11b8818e	19	#define FS_KEY_DERIVATION_NONCE_SIZE 16
cc4e0df0	20
22d94f49 EB	21	#define FSCRYPT_MIN_KEY_SIZE 16
22d94f49 EB	22
5dae460c EB	23	#define FSCRYPT_CONTEXT_V1 1
	24	#define FSCRYPT_CONTEXT_V2 2
	25
	26	struct fscrypt_context_v1 {
	27	u8 version; /* FSCRYPT_CONTEXT_V1 */
cc4e0df0 TT	28	u8 contents_encryption_mode;
	29	u8 filenames_encryption_mode;
	30	u8 flags;
3b6df59b	31	u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
cc4e0df0	32	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
5dae460c	33	};
cc4e0df0	34
5dae460c EB	35	struct fscrypt_context_v2 {
	36	u8 version; /* FSCRYPT_CONTEXT_V2 */
	37	u8 contents_encryption_mode;
	38	u8 filenames_encryption_mode;
	39	u8 flags;
	40	u8 __reserved[4];
	41	u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
	42	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	43	};
	44
	45	/**
	46	* fscrypt_context - the encryption context of an inode
	47	*
	48	* This is the on-disk equivalent of an fscrypt_policy, stored alongside each
	49	* encrypted file usually in a hidden extended attribute. It contains the
	50	* fields from the fscrypt_policy, in order to identify the encryption algorithm
	51	* and key with which the file is encrypted. It also contains a nonce that was
	52	* randomly generated by fscrypt itself; this is used as KDF input or as a tweak
	53	* to cause different files to be encrypted differently.
	54	*/
	55	union fscrypt_context {
	56	u8 version;
	57	struct fscrypt_context_v1 v1;
	58	struct fscrypt_context_v2 v2;
	59	};
	60
	61	/*
	62	* Return the size expected for the given fscrypt_context based on its version
	63	* number, or 0 if the context version is unrecognized.
	64	*/
	65	static inline int fscrypt_context_size(const union fscrypt_context *ctx)
	66	{
	67	switch (ctx->version) {
	68	case FSCRYPT_CONTEXT_V1:
	69	BUILD_BUG_ON(sizeof(ctx->v1) != 28);
	70	return sizeof(ctx->v1);
	71	case FSCRYPT_CONTEXT_V2:
	72	BUILD_BUG_ON(sizeof(ctx->v2) != 40);
	73	return sizeof(ctx->v2);
	74	}
	75	return 0;
	76	}
	77
	78	#undef fscrypt_policy
	79	union fscrypt_policy {
	80	u8 version;
	81	struct fscrypt_policy_v1 v1;
	82	struct fscrypt_policy_v2 v2;
	83	};
	84
	85	/*
	86	* Return the size expected for the given fscrypt_policy based on its version
	87	* number, or 0 if the policy version is unrecognized.
	88	*/
	89	static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
	90	{
	91	switch (policy->version) {
	92	case FSCRYPT_POLICY_V1:
	93	return sizeof(policy->v1);
	94	case FSCRYPT_POLICY_V2:
	95	return sizeof(policy->v2);
	96	}
	97	return 0;
	98	}
99
100	/* Return the contents encryption mode of a valid encryption policy */
101	static inline u8
102	fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
103	{
104	switch (policy->version) {
105	case FSCRYPT_POLICY_V1:
106	return policy->v1.contents_encryption_mode;
107	case FSCRYPT_POLICY_V2:
108	return policy->v2.contents_encryption_mode;
109	}
110	BUG();
111	}
112
113	/* Return the filenames encryption mode of a valid encryption policy */
114	static inline u8
115	fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
116	{
117	switch (policy->version) {
118	case FSCRYPT_POLICY_V1:
119	return policy->v1.filenames_encryption_mode;
120	case FSCRYPT_POLICY_V2:
121	return policy->v2.filenames_encryption_mode;
122	}
123	BUG();
124	}
125
126	/* Return the flags (FSCRYPT_POLICY_FLAG) of a valid encryption policy /
127	static inline u8
128	fscrypt_policy_flags(const union fscrypt_policy *policy)
129	{
130	switch (policy->version) {
131	case FSCRYPT_POLICY_V1:
132	return policy->v1.flags;
133	case FSCRYPT_POLICY_V2:
134	return policy->v2.flags;
135	}
136	BUG();
137	}
138
139	static inline bool
140	fscrypt_is_direct_key_policy(const union fscrypt_policy *policy)
141	{
142	return fscrypt_policy_flags(policy) & FSCRYPT_POLICY_FLAG_DIRECT_KEY;
143	}
cc4e0df0	144
0eaab5b1 EB	145	/**
	146	* For encrypted symlinks, the ciphertext length is stored at the beginning
	147	* of the string in little-endian format.
	148	*/
	149	struct fscrypt_symlink_data {
	150	__le16 len;
	151	char encrypted_path[1];
	152	} __packed;
	153
cc4e0df0	154	/*
8094c3ce EB	155	* fscrypt_info - the "encryption key" for an inode
	156	*
	157	* When an encrypted file's key is made available, an instance of this struct is
	158	* allocated and stored in ->i_crypt_info. Once created, it remains until the
	159	* inode is evicted.
cc4e0df0 TT	160	*/
cc4e0df0 TT	161	struct fscrypt_info {
8094c3ce EB	162
	163	/* The actual crypto transform used for encryption and decryption */
	164	struct crypto_skcipher *ci_ctfm;
	165
b103fb76 EB	166	/* True if the key should be freed when this fscrypt_info is freed */
	167	bool ci_owns_key;
	168
8094c3ce	169	/*
5dae460c EB	170	* Encryption mode used for this inode. It corresponds to either the
5dae460c EB	171	* contents or filenames encryption mode, depending on the inode type.
8094c3ce EB	172	*/
	173	struct fscrypt_mode *ci_mode;
	174
59dc6a8e EB	175	/* Back-pointer to the inode */
	176	struct inode *ci_inode;
	177
b1c0ec35 EB	178	/*
	179	* The master key with which this inode was unlocked (decrypted). This
	180	* will be NULL if the master key was found in a process-subscribed
	181	* keyring rather than in the filesystem-level keyring.
	182	*/
	183	struct key *ci_master_key;
	184
	185	/*
	186	* Link in list of inodes that were unlocked with the master key.
	187	* Only used when ->ci_master_key is set.
	188	*/
	189	struct list_head ci_master_key_link;
	190
8094c3ce	191	/*
a828daab EB	192	* If non-NULL, then encryption is done using the master key directly
a828daab EB	193	* and ci_ctfm will equal ci_direct_key->dk_ctfm.
8094c3ce	194	*/
a828daab	195	struct fscrypt_direct_key *ci_direct_key;
8094c3ce	196
5dae460c EB	197	/* The encryption policy used by this inode */
	198	union fscrypt_policy ci_policy;
	199
	200	/* This inode's nonce, copied from the fscrypt_context */
8094c3ce	201	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
cc4e0df0 TT	202	};
cc4e0df0 TT	203
58ae7468 RW	204	typedef enum {
	205	FS_DECRYPT = 0,
	206	FS_ENCRYPT,
	207	} fscrypt_direction_t;
	208
bb8179e5 EB	209	static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
	210	u32 filenames_mode)
	211	{
3b6df59b EB	212	if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
3b6df59b EB	213	filenames_mode == FSCRYPT_MODE_AES_128_CTS)
bb8179e5 EB	214	return true;
bb8179e5 EB	215
3b6df59b EB	216	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
3b6df59b EB	217	filenames_mode == FSCRYPT_MODE_AES_256_CTS)
bb8179e5 EB	218	return true;
bb8179e5 EB	219
3b6df59b EB	220	if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
3b6df59b EB	221	filenames_mode == FSCRYPT_MODE_ADIANTUM)
8094c3ce EB	222	return true;
8094c3ce EB	223
bb8179e5 EB	224	return false;
	225	}
	226
b98701df	227	/* crypto.c */
e4de782a	228	extern struct kmem_cache *fscrypt_info_cachep;
58ae7468	229	extern int fscrypt_initialize(unsigned int cop_flags);
f47fcbb2 EB	230	extern int fscrypt_crypt_block(const struct inode *inode,
	231	fscrypt_direction_t rw, u64 lblk_num,
	232	struct page src_page, struct page dest_page,
	233	unsigned int len, unsigned int offs,
	234	gfp_t gfp_flags);
d2d0727b	235	extern struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
54222025	236	extern const struct dentry_operations fscrypt_d_ops;
b98701df	237
544d08fd	238	extern void __printf(3, 4) __cold
886da8b3	239	fscrypt_msg(const struct inode inode, const char level, const char *fmt, ...);
544d08fd	240
886da8b3 EB	241	#define fscrypt_warn(inode, fmt, ...) \
	242	fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
	243	#define fscrypt_err(inode, fmt, ...) \
	244	fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
544d08fd	245
8094c3ce EB	246	#define FSCRYPT_MAX_IV_SIZE 32
	247
	248	union fscrypt_iv {
	249	struct {
	250	/* logical block number within the file */
	251	__le64 lblk_num;
	252
	253	/* per-file nonce; only set in DIRECT_KEY mode */
	254	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	255	};
	256	u8 raw[FSCRYPT_MAX_IV_SIZE];
	257	};
	258
	259	void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
	260	const struct fscrypt_info *ci);
	261
76e81d6d	262	/* fname.c */
50c961de EB	263	extern int fname_encrypt(struct inode inode, const struct qstr iname,
50c961de EB	264	u8 *out, unsigned int olen);
b9db0b4a EB	265	extern bool fscrypt_fname_encrypted_size(const struct inode *inode,
	266	u32 orig_len, u32 max_len,
	267	u32 *encrypted_len_ret);
76e81d6d	268
c1144c9b EB	269	/* hkdf.c */
	270
	271	struct fscrypt_hkdf {
	272	struct crypto_shash *hmac_tfm;
	273	};
	274
	275	extern int fscrypt_init_hkdf(struct fscrypt_hkdf hkdf, const u8 master_key,
	276	unsigned int master_key_size);
	277
5dae460c EB	278	/*
	279	* The list of contexts in which fscrypt uses HKDF. These values are used as
	280	* the first byte of the HKDF application-specific info string to guarantee that
	281	* info strings are never repeated between contexts. This ensures that all HKDF
	282	* outputs are unique and cryptographically isolated, i.e. knowledge of one
	283	* output doesn't reveal another.
	284	*/
	285	#define HKDF_CONTEXT_KEY_IDENTIFIER 1
	286	#define HKDF_CONTEXT_PER_FILE_KEY 2
b103fb76 EB	287	#define HKDF_CONTEXT_DIRECT_KEY 3
b103fb76 EB	288	#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4
5dae460c	289
c1144c9b EB	290	extern int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context,
	291	const u8 *info, unsigned int infolen,
	292	u8 *okm, unsigned int okmlen);
	293
	294	extern void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
	295
22d94f49 EB	296	/* keyring.c */
	297
	298	/*
	299	* fscrypt_master_key_secret - secret key material of an in-use master key
	300	*/
	301	struct fscrypt_master_key_secret {
	302
5dae460c EB	303	/*
	304	* For v2 policy keys: HKDF context keyed by this master key.
	305	* For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
	306	*/
	307	struct fscrypt_hkdf hkdf;
	308
	309	/* Size of the raw key in bytes. Set even if ->raw isn't set. */
22d94f49 EB	310	u32 size;
22d94f49 EB	311
5dae460c	312	/* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
22d94f49 EB	313	u8 raw[FSCRYPT_MAX_KEY_SIZE];
	314
	315	} __randomize_layout;
	316
	317	/*
	318	* fscrypt_master_key - an in-use master key
	319	*
	320	* This represents a master encryption key which has been added to the
	321	* filesystem and can be used to "unlock" the encrypted files which were
	322	* encrypted with it.
	323	*/
	324	struct fscrypt_master_key {
	325
b1c0ec35 EB	326	/*
	327	* The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
	328	* executed, this is wiped and no new inodes can be unlocked with this
	329	* key; however, there may still be inodes in ->mk_decrypted_inodes
	330	* which could not be evicted. As long as some inodes still remain,
	331	* FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
	332	* FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
	333	*
23c688b5 EB	334	* Locking: protected by key->sem (outer) and mk_secret_sem (inner).
	335	* The reason for two locks is that key->sem also protects modifying
	336	* mk_users, which ranks it above the semaphore for the keyring key
	337	* type, which is in turn above page faults (via keyring_read). But
	338	* sometimes filesystems call fscrypt_get_encryption_info() from within
	339	* a transaction, which ranks it below page faults. So we need a
	340	* separate lock which protects mk_secret but not also mk_users.
b1c0ec35	341	*/
22d94f49	342	struct fscrypt_master_key_secret mk_secret;
23c688b5	343	struct rw_semaphore mk_secret_sem;
22d94f49	344
5dae460c EB	345	/*
	346	* For v1 policy keys: an arbitrary key descriptor which was assigned by
	347	* userspace (->descriptor).
	348	*
	349	* For v2 policy keys: a cryptographic hash of this key (->identifier).
	350	*/
22d94f49 EB	351	struct fscrypt_key_specifier mk_spec;
22d94f49 EB	352
23c688b5 EB	353	/*
	354	* Keyring which contains a key of type 'key_type_fscrypt_user' for each
	355	* user who has added this key. Normally each key will be added by just
	356	* one user, but it's possible that multiple users share a key, and in
	357	* that case we need to keep track of those users so that one user can't
	358	* remove the key before the others want it removed too.
	359	*
	360	* This is NULL for v1 policy keys; those can only be added by root.
	361	*
	362	* Locking: in addition to this keyrings own semaphore, this is
	363	* protected by the master key's key->sem, so we can do atomic
	364	* search+insert. It can also be searched without taking any locks, but
	365	* in that case the returned key may have already been removed.
	366	*/
	367	struct key *mk_users;
	368
b1c0ec35 EB	369	/*
	370	* Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
	371	* Once this goes to 0, the master key is removed from ->s_master_keys.
	372	* The 'struct fscrypt_master_key' will continue to live as long as the
	373	* 'struct key' whose payload it is, but we won't let this reference
	374	* count rise again.
	375	*/
	376	refcount_t mk_refcount;
	377
	378	/*
	379	* List of inodes that were unlocked using this key. This allows the
	380	* inodes to be evicted efficiently if the key is removed.
	381	*/
	382	struct list_head mk_decrypted_inodes;
	383	spinlock_t mk_decrypted_inodes_lock;
	384
b103fb76 EB	385	/* Crypto API transforms for DIRECT_KEY policies, allocated on-demand */
	386	struct crypto_skcipher *mk_direct_tfms[__FSCRYPT_MODE_MAX + 1];
	387
	388	/*
	389	* Crypto API transforms for filesystem-layer implementation of
	390	* IV_INO_LBLK_64 policies, allocated on-demand.
	391	*/
	392	struct crypto_skcipher *mk_iv_ino_lblk_64_tfms[__FSCRYPT_MODE_MAX + 1];
5dae460c	393
22d94f49 EB	394	} __randomize_layout;
22d94f49 EB	395
b1c0ec35 EB	396	static inline bool
	397	is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
	398	{
	399	/*
	400	* The READ_ONCE() is only necessary for fscrypt_drop_inode() and
	401	* fscrypt_key_describe(). These run in atomic context, so they can't
23c688b5 EB	402	* take ->mk_secret_sem and thus 'secret' can change concurrently which
	403	* would be a data race. But they only need to know whether the secret
	404	* was present at the time of check, so READ_ONCE() suffices.
b1c0ec35 EB	405	*/
	406	return READ_ONCE(secret->size) != 0;
	407	}
	408
22d94f49 EB	409	static inline const char *master_key_spec_type(
	410	const struct fscrypt_key_specifier *spec)
	411	{
	412	switch (spec->type) {
	413	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
	414	return "descriptor";
5dae460c EB	415	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
5dae460c EB	416	return "identifier";
22d94f49 EB	417	}
	418	return "[unknown]";
	419	}
	420
	421	static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
	422	{
	423	switch (spec->type) {
	424	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
	425	return FSCRYPT_KEY_DESCRIPTOR_SIZE;
5dae460c EB	426	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
5dae460c EB	427	return FSCRYPT_KEY_IDENTIFIER_SIZE;
22d94f49 EB	428	}
	429	return 0;
	430	}
	431
	432	extern struct key *
	433	fscrypt_find_master_key(struct super_block *sb,
	434	const struct fscrypt_key_specifier *mk_spec);
	435
5ab7189a EB	436	extern int fscrypt_verify_key_added(struct super_block *sb,
	437	const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
	438
22d94f49 EB	439	extern int __init fscrypt_init_keyring(void);
22d94f49 EB	440
feed8258	441	/* keysetup.c */
8094c3ce EB	442
	443	struct fscrypt_mode {
	444	const char *friendly_name;
	445	const char *cipher_str;
	446	int keysize;
	447	int ivsize;
ff73c2c0	448	int logged_impl_name;
8094c3ce EB	449	};
8094c3ce EB	450
3ec4f2a6 EB	451	static inline bool
	452	fscrypt_mode_supports_direct_key(const struct fscrypt_mode *mode)
	453	{
	454	return mode->ivsize >= offsetofend(union fscrypt_iv, nonce);
	455	}
	456
0109ce76 EB	457	extern struct crypto_skcipher *
	458	fscrypt_allocate_skcipher(struct fscrypt_mode mode, const u8 raw_key,
	459	const struct inode *inode);
	460
	461	extern int fscrypt_set_derived_key(struct fscrypt_info *ci,
	462	const u8 *derived_key);
	463
	464	/* keysetup_v1.c */
	465
	466	extern void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
	467
	468	extern int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
	469	const u8 *raw_master_key);
	470
	471	extern int fscrypt_setup_v1_file_key_via_subscribed_keyrings(
	472	struct fscrypt_info *ci);
5dae460c EB	473	/* policy.c */
	474
	475	extern bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
	476	const union fscrypt_policy *policy2);
	477	extern bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
	478	const struct inode *inode);
	479	extern int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
	480	const union fscrypt_context *ctx_u,
	481	int ctx_size);
0109ce76	482
3325bea5	483	#endif /* _FSCRYPT_PRIVATE_H */