[people/ms/linux.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 <linux/siphash.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;
}

/* 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)
{
	return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx);
}

/* Retrieve the context's nonce, assuming the context was already validated */
static inline const u8 *fscrypt_context_nonce(const union fscrypt_context *ctx)
{
	switch (ctx->version) {
	case FSCRYPT_CONTEXT_V1:
		return ctx->v1.nonce;
	case FSCRYPT_CONTEXT_V2:
		return ctx->v2.nonce;
	}
	WARN_ON(1);
	return NULL;
}

#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();
}

/*
 * 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;

	/*
	 * This inode's hash key for filenames.  This is a 128-bit SipHash-2-4
	 * key.  This is only set for directories that use a keyed dirhash over
	 * the plaintext filenames -- currently just casefolded directories.
	 */
	siphash_key_t ci_dirhash_key;
	bool ci_dirhash_key_initialized;

	/* 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];

	/* Hashed inode number.  Only set for IV_INO_LBLK_32 */
	u32 ci_hashed_ino;
};

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

/* crypto.c */
extern struct kmem_cache *fscrypt_info_cachep;
int fscrypt_initialize(unsigned int cop_flags);
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);
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, ...)		\
	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 */
int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
			  u8 *out, unsigned int olen);
bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
				  u32 max_len, u32 *encrypted_len_ret);
extern const struct dentry_operations fscrypt_d_ops;

/* hkdf.c */

struct fscrypt_hkdf {
	struct crypto_shash *hmac_tfm;
};

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_ENC_KEY	2
#define HKDF_CONTEXT_DIRECT_KEY		3
#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY	4
#define HKDF_CONTEXT_DIRHASH_KEY	5
#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY	6
#define HKDF_CONTEXT_INODE_HASH_KEY	7

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);

/* 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;

	/*
	 * Per-mode encryption keys for the various types of encryption policies
	 * that use them.  Allocated and derived on-demand.
	 */
	struct crypto_skcipher *mk_direct_keys[__FSCRYPT_MODE_MAX + 1];
	struct crypto_skcipher *mk_iv_ino_lblk_64_keys[__FSCRYPT_MODE_MAX + 1];
	struct crypto_skcipher *mk_iv_ino_lblk_32_keys[__FSCRYPT_MODE_MAX + 1];

	/* Hash key for inode numbers.  Initialized only when needed. */
	siphash_key_t		mk_ino_hash_key;
	bool			mk_ino_hash_key_initialized;

} __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;
}

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

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

extern struct fscrypt_mode fscrypt_modes[];

struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
						  const u8 *raw_key,
						  const struct inode *inode);

int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key);

int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
			       const struct fscrypt_master_key *mk);

/* keysetup_v1.c */

void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);

int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
			      const u8 *raw_master_key);

int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);

/* policy.c */

bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
			    const union fscrypt_policy *policy2);
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);

#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>
aa408f83	15	#include <linux/siphash.h>
b7e7cf7a	16	#include <crypto/hash.h>
3325bea5	17
22d94f49 EB	18	#define CONST_STRLEN(str) (sizeof(str) - 1)
22d94f49 EB	19
11b8818e	20	#define FS_KEY_DERIVATION_NONCE_SIZE 16
cc4e0df0	21
22d94f49 EB	22	#define FSCRYPT_MIN_KEY_SIZE 16
22d94f49 EB	23
5dae460c EB	24	#define FSCRYPT_CONTEXT_V1 1
	25	#define FSCRYPT_CONTEXT_V2 2
	26
	27	struct fscrypt_context_v1 {
	28	u8 version; /* FSCRYPT_CONTEXT_V1 */
cc4e0df0 TT	29	u8 contents_encryption_mode;
	30	u8 filenames_encryption_mode;
	31	u8 flags;
3b6df59b	32	u8 master_key_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
cc4e0df0	33	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
5dae460c	34	};
cc4e0df0	35
5dae460c EB	36	struct fscrypt_context_v2 {
	37	u8 version; /* FSCRYPT_CONTEXT_V2 */
	38	u8 contents_encryption_mode;
	39	u8 filenames_encryption_mode;
	40	u8 flags;
	41	u8 __reserved[4];
	42	u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
	43	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	44	};
	45
d2fe9754	46	/*
5dae460c EB	47	* fscrypt_context - the encryption context of an inode
	48	*
	49	* This is the on-disk equivalent of an fscrypt_policy, stored alongside each
	50	* encrypted file usually in a hidden extended attribute. It contains the
	51	* fields from the fscrypt_policy, in order to identify the encryption algorithm
	52	* and key with which the file is encrypted. It also contains a nonce that was
	53	* randomly generated by fscrypt itself; this is used as KDF input or as a tweak
	54	* to cause different files to be encrypted differently.
	55	*/
	56	union fscrypt_context {
	57	u8 version;
	58	struct fscrypt_context_v1 v1;
	59	struct fscrypt_context_v2 v2;
	60	};
	61
	62	/*
	63	* Return the size expected for the given fscrypt_context based on its version
	64	* number, or 0 if the context version is unrecognized.
	65	*/
	66	static inline int fscrypt_context_size(const union fscrypt_context *ctx)
	67	{
	68	switch (ctx->version) {
	69	case FSCRYPT_CONTEXT_V1:
	70	BUILD_BUG_ON(sizeof(ctx->v1) != 28);
	71	return sizeof(ctx->v1);
	72	case FSCRYPT_CONTEXT_V2:
	73	BUILD_BUG_ON(sizeof(ctx->v2) != 40);
	74	return sizeof(ctx->v2);
	75	}
	76	return 0;
	77	}
	78
e98ad464 EB	79	/* Check whether an fscrypt_context has a recognized version number and size */
	80	static inline bool fscrypt_context_is_valid(const union fscrypt_context *ctx,
	81	int ctx_size)
	82	{
	83	return ctx_size >= 1 && ctx_size == fscrypt_context_size(ctx);
	84	}
	85
	86	/* Retrieve the context's nonce, assuming the context was already validated */
	87	static inline const u8 fscrypt_context_nonce(const union fscrypt_context ctx)
	88	{
	89	switch (ctx->version) {
	90	case FSCRYPT_CONTEXT_V1:
	91	return ctx->v1.nonce;
	92	case FSCRYPT_CONTEXT_V2:
	93	return ctx->v2.nonce;
	94	}
	95	WARN_ON(1);
	96	return NULL;
	97	}
	98
5dae460c EB	99	#undef fscrypt_policy
	100	union fscrypt_policy {
	101	u8 version;
	102	struct fscrypt_policy_v1 v1;
	103	struct fscrypt_policy_v2 v2;
	104	};
	105
	106	/*
	107	* Return the size expected for the given fscrypt_policy based on its version
	108	* number, or 0 if the policy version is unrecognized.
	109	*/
	110	static inline int fscrypt_policy_size(const union fscrypt_policy *policy)
	111	{
	112	switch (policy->version) {
	113	case FSCRYPT_POLICY_V1:
	114	return sizeof(policy->v1);
	115	case FSCRYPT_POLICY_V2:
	116	return sizeof(policy->v2);
	117	}
	118	return 0;
	119	}
	120
	121	/* Return the contents encryption mode of a valid encryption policy */
	122	static inline u8
	123	fscrypt_policy_contents_mode(const union fscrypt_policy *policy)
	124	{
	125	switch (policy->version) {
	126	case FSCRYPT_POLICY_V1:
	127	return policy->v1.contents_encryption_mode;
	128	case FSCRYPT_POLICY_V2:
	129	return policy->v2.contents_encryption_mode;
	130	}
	131	BUG();
	132	}
	133
	134	/* Return the filenames encryption mode of a valid encryption policy */
	135	static inline u8
	136	fscrypt_policy_fnames_mode(const union fscrypt_policy *policy)
	137	{
	138	switch (policy->version) {
	139	case FSCRYPT_POLICY_V1:
	140	return policy->v1.filenames_encryption_mode;
	141	case FSCRYPT_POLICY_V2:
	142	return policy->v2.filenames_encryption_mode;
	143	}
	144	BUG();
	145	}
	146
	147	/* Return the flags (FSCRYPT_POLICY_FLAG) of a valid encryption policy /
	148	static inline u8
	149	fscrypt_policy_flags(const union fscrypt_policy *policy)
	150	{
	151	switch (policy->version) {
	152	case FSCRYPT_POLICY_V1:
	153	return policy->v1.flags;
	154	case FSCRYPT_POLICY_V2:
	155	return policy->v2.flags;
	156	}
	157	BUG();
	158	}
	159
d2fe9754	160	/*
0eaab5b1 EB	161	* For encrypted symlinks, the ciphertext length is stored at the beginning
	162	* of the string in little-endian format.
	163	*/
	164	struct fscrypt_symlink_data {
	165	__le16 len;
	166	char encrypted_path[1];
	167	} __packed;
	168
cc4e0df0	169	/*
8094c3ce EB	170	* fscrypt_info - the "encryption key" for an inode
	171	*
	172	* When an encrypted file's key is made available, an instance of this struct is
	173	* allocated and stored in ->i_crypt_info. Once created, it remains until the
	174	* inode is evicted.
cc4e0df0 TT	175	*/
cc4e0df0 TT	176	struct fscrypt_info {
8094c3ce EB	177
	178	/* The actual crypto transform used for encryption and decryption */
	179	struct crypto_skcipher *ci_ctfm;
	180
b103fb76 EB	181	/* True if the key should be freed when this fscrypt_info is freed */
	182	bool ci_owns_key;
	183
8094c3ce	184	/*
5dae460c EB	185	* Encryption mode used for this inode. It corresponds to either the
5dae460c EB	186	* contents or filenames encryption mode, depending on the inode type.
8094c3ce EB	187	*/
	188	struct fscrypt_mode *ci_mode;
	189
59dc6a8e EB	190	/* Back-pointer to the inode */
	191	struct inode *ci_inode;
	192
b1c0ec35 EB	193	/*
	194	* The master key with which this inode was unlocked (decrypted). This
	195	* will be NULL if the master key was found in a process-subscribed
	196	* keyring rather than in the filesystem-level keyring.
	197	*/
	198	struct key *ci_master_key;
	199
	200	/*
	201	* Link in list of inodes that were unlocked with the master key.
	202	* Only used when ->ci_master_key is set.
	203	*/
	204	struct list_head ci_master_key_link;
	205
8094c3ce	206	/*
a828daab EB	207	* If non-NULL, then encryption is done using the master key directly
a828daab EB	208	* and ci_ctfm will equal ci_direct_key->dk_ctfm.
8094c3ce	209	*/
a828daab	210	struct fscrypt_direct_key *ci_direct_key;
8094c3ce	211
aa408f83 DR	212	/*
	213	* This inode's hash key for filenames. This is a 128-bit SipHash-2-4
	214	* key. This is only set for directories that use a keyed dirhash over
	215	* the plaintext filenames -- currently just casefolded directories.
	216	*/
	217	siphash_key_t ci_dirhash_key;
	218	bool ci_dirhash_key_initialized;
	219
5dae460c EB	220	/* The encryption policy used by this inode */
	221	union fscrypt_policy ci_policy;
	222
	223	/* This inode's nonce, copied from the fscrypt_context */
8094c3ce	224	u8 ci_nonce[FS_KEY_DERIVATION_NONCE_SIZE];
e3b1078b EB	225
	226	/* Hashed inode number. Only set for IV_INO_LBLK_32 */
	227	u32 ci_hashed_ino;
cc4e0df0 TT	228	};
cc4e0df0 TT	229
58ae7468 RW	230	typedef enum {
	231	FS_DECRYPT = 0,
	232	FS_ENCRYPT,
	233	} fscrypt_direction_t;
	234
b98701df	235	/* crypto.c */
e4de782a	236	extern struct kmem_cache *fscrypt_info_cachep;
60700902 EB	237	int fscrypt_initialize(unsigned int cop_flags);
	238	int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
	239	u64 lblk_num, struct page *src_page,
	240	struct page *dest_page, unsigned int len,
	241	unsigned int offs, gfp_t gfp_flags);
	242	struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags);
	243
	244	void __printf(3, 4) __cold
886da8b3	245	fscrypt_msg(const struct inode inode, const char level, const char *fmt, ...);
544d08fd	246
886da8b3 EB	247	#define fscrypt_warn(inode, fmt, ...) \
	248	fscrypt_msg((inode), KERN_WARNING, fmt, ##__VA_ARGS__)
	249	#define fscrypt_err(inode, fmt, ...) \
	250	fscrypt_msg((inode), KERN_ERR, fmt, ##__VA_ARGS__)
544d08fd	251
8094c3ce EB	252	#define FSCRYPT_MAX_IV_SIZE 32
	253
	254	union fscrypt_iv {
	255	struct {
	256	/* logical block number within the file */
	257	__le64 lblk_num;
	258
	259	/* per-file nonce; only set in DIRECT_KEY mode */
	260	u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE];
	261	};
	262	u8 raw[FSCRYPT_MAX_IV_SIZE];
	263	};
	264
	265	void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
	266	const struct fscrypt_info *ci);
	267
76e81d6d	268	/* fname.c */
60700902 EB	269	int fscrypt_fname_encrypt(const struct inode inode, const struct qstr iname,
	270	u8 *out, unsigned int olen);
	271	bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
	272	u32 max_len, u32 *encrypted_len_ret);
2ebdef6d	273	extern const struct dentry_operations fscrypt_d_ops;
76e81d6d	274
c1144c9b EB	275	/* hkdf.c */
	276
	277	struct fscrypt_hkdf {
	278	struct crypto_shash *hmac_tfm;
	279	};
	280
60700902 EB	281	int fscrypt_init_hkdf(struct fscrypt_hkdf hkdf, const u8 master_key,
60700902 EB	282	unsigned int master_key_size);
c1144c9b	283
5dae460c EB	284	/*
	285	* The list of contexts in which fscrypt uses HKDF. These values are used as
	286	* the first byte of the HKDF application-specific info string to guarantee that
	287	* info strings are never repeated between contexts. This ensures that all HKDF
	288	* outputs are unique and cryptographically isolated, i.e. knowledge of one
	289	* output doesn't reveal another.
	290	*/
	291	#define HKDF_CONTEXT_KEY_IDENTIFIER 1
f592efe7	292	#define HKDF_CONTEXT_PER_FILE_ENC_KEY 2
b103fb76 EB	293	#define HKDF_CONTEXT_DIRECT_KEY 3
b103fb76 EB	294	#define HKDF_CONTEXT_IV_INO_LBLK_64_KEY 4
aa408f83	295	#define HKDF_CONTEXT_DIRHASH_KEY 5
e3b1078b EB	296	#define HKDF_CONTEXT_IV_INO_LBLK_32_KEY 6
e3b1078b EB	297	#define HKDF_CONTEXT_INODE_HASH_KEY 7
5dae460c	298
60700902 EB	299	int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
	300	const u8 *info, unsigned int infolen,
	301	u8 *okm, unsigned int okmlen);
c1144c9b	302
60700902	303	void fscrypt_destroy_hkdf(struct fscrypt_hkdf *hkdf);
c1144c9b	304
22d94f49 EB	305	/* keyring.c */
	306
	307	/*
	308	* fscrypt_master_key_secret - secret key material of an in-use master key
	309	*/
	310	struct fscrypt_master_key_secret {
	311
5dae460c EB	312	/*
	313	* For v2 policy keys: HKDF context keyed by this master key.
	314	* For v1 policy keys: not set (hkdf.hmac_tfm == NULL).
	315	*/
	316	struct fscrypt_hkdf hkdf;
	317
	318	/* Size of the raw key in bytes. Set even if ->raw isn't set. */
22d94f49 EB	319	u32 size;
22d94f49 EB	320
5dae460c	321	/* For v1 policy keys: the raw key. Wiped for v2 policy keys. */
22d94f49 EB	322	u8 raw[FSCRYPT_MAX_KEY_SIZE];
	323
	324	} __randomize_layout;
	325
	326	/*
	327	* fscrypt_master_key - an in-use master key
	328	*
	329	* This represents a master encryption key which has been added to the
	330	* filesystem and can be used to "unlock" the encrypted files which were
	331	* encrypted with it.
	332	*/
	333	struct fscrypt_master_key {
	334
b1c0ec35 EB	335	/*
	336	* The secret key material. After FS_IOC_REMOVE_ENCRYPTION_KEY is
	337	* executed, this is wiped and no new inodes can be unlocked with this
	338	* key; however, there may still be inodes in ->mk_decrypted_inodes
	339	* which could not be evicted. As long as some inodes still remain,
	340	* FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
	341	* FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
	342	*
23c688b5 EB	343	* Locking: protected by key->sem (outer) and mk_secret_sem (inner).
	344	* The reason for two locks is that key->sem also protects modifying
	345	* mk_users, which ranks it above the semaphore for the keyring key
	346	* type, which is in turn above page faults (via keyring_read). But
	347	* sometimes filesystems call fscrypt_get_encryption_info() from within
	348	* a transaction, which ranks it below page faults. So we need a
	349	* separate lock which protects mk_secret but not also mk_users.
b1c0ec35	350	*/
22d94f49	351	struct fscrypt_master_key_secret mk_secret;
23c688b5	352	struct rw_semaphore mk_secret_sem;
22d94f49	353
5dae460c EB	354	/*
	355	* For v1 policy keys: an arbitrary key descriptor which was assigned by
	356	* userspace (->descriptor).
	357	*
	358	* For v2 policy keys: a cryptographic hash of this key (->identifier).
	359	*/
22d94f49 EB	360	struct fscrypt_key_specifier mk_spec;
22d94f49 EB	361
23c688b5 EB	362	/*
	363	* Keyring which contains a key of type 'key_type_fscrypt_user' for each
	364	* user who has added this key. Normally each key will be added by just
	365	* one user, but it's possible that multiple users share a key, and in
	366	* that case we need to keep track of those users so that one user can't
	367	* remove the key before the others want it removed too.
	368	*
	369	* This is NULL for v1 policy keys; those can only be added by root.
	370	*
	371	* Locking: in addition to this keyrings own semaphore, this is
	372	* protected by the master key's key->sem, so we can do atomic
	373	* search+insert. It can also be searched without taking any locks, but
	374	* in that case the returned key may have already been removed.
	375	*/
	376	struct key *mk_users;
	377
b1c0ec35 EB	378	/*
	379	* Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
	380	* Once this goes to 0, the master key is removed from ->s_master_keys.
	381	* The 'struct fscrypt_master_key' will continue to live as long as the
	382	* 'struct key' whose payload it is, but we won't let this reference
	383	* count rise again.
	384	*/
	385	refcount_t mk_refcount;
	386
	387	/*
	388	* List of inodes that were unlocked using this key. This allows the
	389	* inodes to be evicted efficiently if the key is removed.
	390	*/
	391	struct list_head mk_decrypted_inodes;
	392	spinlock_t mk_decrypted_inodes_lock;
	393
b103fb76	394	/*
e3b1078b EB	395	* Per-mode encryption keys for the various types of encryption policies
e3b1078b EB	396	* that use them. Allocated and derived on-demand.
b103fb76	397	*/
e3b1078b EB	398	struct crypto_skcipher *mk_direct_keys[__FSCRYPT_MODE_MAX + 1];
	399	struct crypto_skcipher *mk_iv_ino_lblk_64_keys[__FSCRYPT_MODE_MAX + 1];
	400	struct crypto_skcipher *mk_iv_ino_lblk_32_keys[__FSCRYPT_MODE_MAX + 1];
	401
	402	/* Hash key for inode numbers. Initialized only when needed. */
	403	siphash_key_t mk_ino_hash_key;
	404	bool mk_ino_hash_key_initialized;
5dae460c	405
22d94f49 EB	406	} __randomize_layout;
22d94f49 EB	407
b1c0ec35 EB	408	static inline bool
	409	is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
	410	{
	411	/*
	412	* The READ_ONCE() is only necessary for fscrypt_drop_inode() and
	413	* fscrypt_key_describe(). These run in atomic context, so they can't
23c688b5 EB	414	* take ->mk_secret_sem and thus 'secret' can change concurrently which
	415	* would be a data race. But they only need to know whether the secret
	416	* was present at the time of check, so READ_ONCE() suffices.
b1c0ec35 EB	417	*/
	418	return READ_ONCE(secret->size) != 0;
	419	}
	420
22d94f49 EB	421	static inline const char *master_key_spec_type(
	422	const struct fscrypt_key_specifier *spec)
	423	{
	424	switch (spec->type) {
	425	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
	426	return "descriptor";
5dae460c EB	427	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
5dae460c EB	428	return "identifier";
22d94f49 EB	429	}
	430	return "[unknown]";
	431	}
	432
	433	static inline int master_key_spec_len(const struct fscrypt_key_specifier *spec)
	434	{
	435	switch (spec->type) {
	436	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
	437	return FSCRYPT_KEY_DESCRIPTOR_SIZE;
5dae460c EB	438	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
5dae460c EB	439	return FSCRYPT_KEY_IDENTIFIER_SIZE;
22d94f49 EB	440	}
	441	return 0;
	442	}
	443
60700902	444	struct key *
22d94f49 EB	445	fscrypt_find_master_key(struct super_block *sb,
	446	const struct fscrypt_key_specifier *mk_spec);
	447
cdeb21da EB	448	int fscrypt_add_test_dummy_key(struct super_block *sb,
	449	struct fscrypt_key_specifier *key_spec);
	450
60700902 EB	451	int fscrypt_verify_key_added(struct super_block *sb,
60700902 EB	452	const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
5ab7189a	453
60700902	454	int __init fscrypt_init_keyring(void);
22d94f49	455
feed8258	456	/* keysetup.c */
8094c3ce EB	457
	458	struct fscrypt_mode {
	459	const char *friendly_name;
	460	const char *cipher_str;
	461	int keysize;
	462	int ivsize;
ff73c2c0	463	int logged_impl_name;
8094c3ce EB	464	};
8094c3ce EB	465
85af90e5	466	extern struct fscrypt_mode fscrypt_modes[];
3ec4f2a6	467
60700902 EB	468	struct crypto_skcipher fscrypt_allocate_skcipher(struct fscrypt_mode mode,
	469	const u8 *raw_key,
	470	const struct inode *inode);
0109ce76	471
60700902	472	int fscrypt_set_per_file_enc_key(struct fscrypt_info ci, const u8 raw_key);
0109ce76	473
60700902 EB	474	int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
60700902 EB	475	const struct fscrypt_master_key *mk);
aa408f83	476
0109ce76 EB	477	/* keysetup_v1.c */
0109ce76 EB	478
60700902	479	void fscrypt_put_direct_key(struct fscrypt_direct_key *dk);
0109ce76	480
60700902 EB	481	int fscrypt_setup_v1_file_key(struct fscrypt_info *ci,
	482	const u8 *raw_master_key);
	483
	484	int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci);
0109ce76	485
5dae460c EB	486	/* policy.c */
5dae460c EB	487
60700902 EB	488	bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
	489	const union fscrypt_policy *policy2);
	490	bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
	491	const struct inode *inode);
	492	int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
	493	const union fscrypt_context *ctx_u,
	494	int ctx_size);
0109ce76	495
3325bea5	496	#endif /* _FSCRYPT_PRIVATE_H */