Commit a828daab authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: rename fscrypt_master_key to fscrypt_direct_key 



In preparation for introducing a filesystem-level keyring which will
contain fscrypt master keys, rename the existing 'struct
fscrypt_master_key' to 'struct fscrypt_direct_key'.  This is the
structure in the existing table of master keys that's maintained to
deduplicate the crypto transforms for v1 DIRECT_KEY policies.

I've chosen to keep this table as-is rather than make it automagically
add/remove the keys to/from the filesystem-level keyring, since that
would add a lot of extra complexity to the filesystem-level keyring.

Reviewed-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 59dc6a8e

fs/crypto/fscrypt_private.h

+3 −4
Original line number Diff line number Diff line
@@ -77,11 +77,10 @@ struct fscrypt_info { 
	struct inode *ci_inode;



	/*

	 * If non-NULL, then this inode uses a master key directly rather than a

	 * derived key, and ci_ctfm will equal ci_master_key->mk_ctfm.

	 * Otherwise, this inode uses a derived key.

	 * If non-NULL, then encryption is done using the master key directly

	 * and ci_ctfm will equal ci_direct_key->dk_ctfm.

	 */

	struct fscrypt_master_key *ci_master_key;

	struct fscrypt_direct_key *ci_direct_key;



	/* fields from the fscrypt_context */

	u8 ci_data_mode;

fs/crypto/keyinfo.c

+65 −65
Original line number Diff line number Diff line
@@ -21,8 +21,8 @@ 
static struct crypto_shash *essiv_hash_tfm;



/* Table of keys referenced by DIRECT_KEY policies */

static DEFINE_HASHTABLE(fscrypt_master_keys, 6); /* 6 bits = 64 buckets */

static DEFINE_SPINLOCK(fscrypt_master_keys_lock);

static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */

static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);



/*

 * Key derivation function.  This generates the derived key by encrypting the
@@ -273,46 +273,46 @@ err_free_tfm: 
}



/* Master key referenced by DIRECT_KEY policy */

struct fscrypt_master_key {

	struct hlist_node mk_node;

	refcount_t mk_refcount;

	const struct fscrypt_mode *mk_mode;

	struct crypto_skcipher *mk_ctfm;

	u8 mk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];

	u8 mk_raw[FSCRYPT_MAX_KEY_SIZE];

struct fscrypt_direct_key {

	struct hlist_node		dk_node;

	refcount_t			dk_refcount;

	const struct fscrypt_mode	*dk_mode;

	struct crypto_skcipher		*dk_ctfm;

	u8				dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];

	u8				dk_raw[FSCRYPT_MAX_KEY_SIZE];

};



static void free_master_key(struct fscrypt_master_key *mk)

static void free_direct_key(struct fscrypt_direct_key *dk)

{

	if (mk) {

		crypto_free_skcipher(mk->mk_ctfm);

		kzfree(mk);

	if (dk) {

		crypto_free_skcipher(dk->dk_ctfm);

		kzfree(dk);

	}

}



static void put_master_key(struct fscrypt_master_key *mk)

static void put_direct_key(struct fscrypt_direct_key *dk)

{

	if (!refcount_dec_and_lock(&mk->mk_refcount, &fscrypt_master_keys_lock))

	if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))

		return;

	hash_del(&mk->mk_node);

	spin_unlock(&fscrypt_master_keys_lock);

	hash_del(&dk->dk_node);

	spin_unlock(&fscrypt_direct_keys_lock);



	free_master_key(mk);

	free_direct_key(dk);

}



/*

 * Find/insert the given master key into the fscrypt_master_keys table.  If

 * found, it is returned with elevated refcount, and 'to_insert' is freed if

 * non-NULL.  If not found, 'to_insert' is inserted and returned if it's

 * non-NULL; otherwise NULL is returned.

 * Find/insert the given key into the fscrypt_direct_keys table.  If found, it

 * is returned with elevated refcount, and 'to_insert' is freed if non-NULL.  If

 * not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise

 * NULL is returned.

 */

static struct fscrypt_master_key *

find_or_insert_master_key(struct fscrypt_master_key *to_insert,

static struct fscrypt_direct_key *

find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,

			  const u8 *raw_key, const struct fscrypt_mode *mode,

			  const struct fscrypt_info *ci)

{

	unsigned long hash_key;

	struct fscrypt_master_key *mk;

	struct fscrypt_direct_key *dk;



	/*

	 * Careful: to avoid potentially leaking secret key bytes via timing
@@ -323,60 +323,60 @@ find_or_insert_master_key(struct fscrypt_master_key *to_insert, 
	BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);

	memcpy(&hash_key, ci->ci_master_key_descriptor, sizeof(hash_key));



	spin_lock(&fscrypt_master_keys_lock);

	hash_for_each_possible(fscrypt_master_keys, mk, mk_node, hash_key) {

		if (memcmp(ci->ci_master_key_descriptor, mk->mk_descriptor,

	spin_lock(&fscrypt_direct_keys_lock);

	hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {

		if (memcmp(ci->ci_master_key_descriptor, dk->dk_descriptor,

			   FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)

			continue;

		if (mode != mk->mk_mode)

		if (mode != dk->dk_mode)

			continue;

		if (crypto_memneq(raw_key, mk->mk_raw, mode->keysize))

		if (crypto_memneq(raw_key, dk->dk_raw, mode->keysize))

			continue;

		/* using existing tfm with same (descriptor, mode, raw_key) */

		refcount_inc(&mk->mk_refcount);

		spin_unlock(&fscrypt_master_keys_lock);

		free_master_key(to_insert);

		return mk;

		refcount_inc(&dk->dk_refcount);

		spin_unlock(&fscrypt_direct_keys_lock);

		free_direct_key(to_insert);

		return dk;

	}

	if (to_insert)

		hash_add(fscrypt_master_keys, &to_insert->mk_node, hash_key);

	spin_unlock(&fscrypt_master_keys_lock);

		hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);

	spin_unlock(&fscrypt_direct_keys_lock);

	return to_insert;

}



/* Prepare to encrypt directly using the master key in the given mode */

static struct fscrypt_master_key *

fscrypt_get_master_key(const struct fscrypt_info *ci, struct fscrypt_mode *mode,

static struct fscrypt_direct_key *

fscrypt_get_direct_key(const struct fscrypt_info *ci, struct fscrypt_mode *mode,

		       const u8 *raw_key, const struct inode *inode)

{

	struct fscrypt_master_key *mk;

	struct fscrypt_direct_key *dk;

	int err;



	/* Is there already a tfm for this key? */

	mk = find_or_insert_master_key(NULL, raw_key, mode, ci);

	if (mk)

		return mk;

	dk = find_or_insert_direct_key(NULL, raw_key, mode, ci);

	if (dk)

		return dk;



	/* Nope, allocate one. */

	mk = kzalloc(sizeof(*mk), GFP_NOFS);

	if (!mk)

	dk = kzalloc(sizeof(*dk), GFP_NOFS);

	if (!dk)

		return ERR_PTR(-ENOMEM);

	refcount_set(&mk->mk_refcount, 1);

	mk->mk_mode = mode;

	mk->mk_ctfm = allocate_skcipher_for_mode(mode, raw_key, inode);

	if (IS_ERR(mk->mk_ctfm)) {

		err = PTR_ERR(mk->mk_ctfm);

		mk->mk_ctfm = NULL;

		goto err_free_mk;

	}

	memcpy(mk->mk_descriptor, ci->ci_master_key_descriptor,

	refcount_set(&dk->dk_refcount, 1);

	dk->dk_mode = mode;

	dk->dk_ctfm = allocate_skcipher_for_mode(mode, raw_key, inode);

	if (IS_ERR(dk->dk_ctfm)) {

		err = PTR_ERR(dk->dk_ctfm);

		dk->dk_ctfm = NULL;

		goto err_free_dk;

	}

	memcpy(dk->dk_descriptor, ci->ci_master_key_descriptor,

	       FSCRYPT_KEY_DESCRIPTOR_SIZE);

	memcpy(mk->mk_raw, raw_key, mode->keysize);

	memcpy(dk->dk_raw, raw_key, mode->keysize);



	return find_or_insert_master_key(mk, raw_key, mode, ci);

	return find_or_insert_direct_key(dk, raw_key, mode, ci);



err_free_mk:

	free_master_key(mk);

err_free_dk:

	free_direct_key(dk);

	return ERR_PTR(err);

}
@@ -455,22 +455,22 @@ static int setup_crypto_transform(struct fscrypt_info *ci, 
				  struct fscrypt_mode *mode,

				  const u8 *raw_key, const struct inode *inode)

{

	struct fscrypt_master_key *mk;

	struct fscrypt_direct_key *dk;

	struct crypto_skcipher *ctfm;

	int err;



	if (ci->ci_flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {

		mk = fscrypt_get_master_key(ci, mode, raw_key, inode);

		if (IS_ERR(mk))

			return PTR_ERR(mk);

		ctfm = mk->mk_ctfm;

		dk = fscrypt_get_direct_key(ci, mode, raw_key, inode);

		if (IS_ERR(dk))

			return PTR_ERR(dk);

		ctfm = dk->dk_ctfm;

	} else {

		mk = NULL;

		dk = NULL;

		ctfm = allocate_skcipher_for_mode(mode, raw_key, inode);

		if (IS_ERR(ctfm))

			return PTR_ERR(ctfm);

	}

	ci->ci_master_key = mk;

	ci->ci_direct_key = dk;

	ci->ci_ctfm = ctfm;



	if (mode->needs_essiv) {
@@ -494,8 +494,8 @@ static void put_crypt_info(struct fscrypt_info *ci) 
	if (!ci)

		return;



	if (ci->ci_master_key) {

		put_master_key(ci->ci_master_key);

	if (ci->ci_direct_key) {

		put_direct_key(ci->ci_direct_key);

	} else {

		crypto_free_skcipher(ci->ci_ctfm);

		crypto_free_cipher(ci->ci_essiv_tfm);

CRA Git | Maintained and supported by SUSTech CRA and CCSE