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736 lines
22 KiB
736 lines
22 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* Key setup facility for FS encryption support. |
|
* |
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* Copyright (C) 2015, Google, Inc. |
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* |
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* Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar. |
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* Heavily modified since then. |
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*/ |
|
|
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#include <crypto/skcipher.h> |
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#include <linux/key.h> |
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#include <linux/random.h> |
|
|
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#include "fscrypt_private.h" |
|
|
|
struct fscrypt_mode fscrypt_modes[] = { |
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[FSCRYPT_MODE_AES_256_XTS] = { |
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.friendly_name = "AES-256-XTS", |
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.cipher_str = "xts(aes)", |
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.keysize = 64, |
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.ivsize = 16, |
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS, |
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}, |
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[FSCRYPT_MODE_AES_256_CTS] = { |
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.friendly_name = "AES-256-CTS-CBC", |
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.cipher_str = "cts(cbc(aes))", |
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.keysize = 32, |
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.ivsize = 16, |
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}, |
|
[FSCRYPT_MODE_AES_128_CBC] = { |
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.friendly_name = "AES-128-CBC-ESSIV", |
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.cipher_str = "essiv(cbc(aes),sha256)", |
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.keysize = 16, |
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.ivsize = 16, |
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV, |
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}, |
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[FSCRYPT_MODE_AES_128_CTS] = { |
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.friendly_name = "AES-128-CTS-CBC", |
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.cipher_str = "cts(cbc(aes))", |
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.keysize = 16, |
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.ivsize = 16, |
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}, |
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[FSCRYPT_MODE_ADIANTUM] = { |
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.friendly_name = "Adiantum", |
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.cipher_str = "adiantum(xchacha12,aes)", |
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.keysize = 32, |
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.ivsize = 32, |
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.blk_crypto_mode = BLK_ENCRYPTION_MODE_ADIANTUM, |
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}, |
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}; |
|
|
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static DEFINE_MUTEX(fscrypt_mode_key_setup_mutex); |
|
|
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static struct fscrypt_mode * |
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select_encryption_mode(const union fscrypt_policy *policy, |
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const struct inode *inode) |
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{ |
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BUILD_BUG_ON(ARRAY_SIZE(fscrypt_modes) != FSCRYPT_MODE_MAX + 1); |
|
|
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if (S_ISREG(inode->i_mode)) |
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return &fscrypt_modes[fscrypt_policy_contents_mode(policy)]; |
|
|
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if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) |
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return &fscrypt_modes[fscrypt_policy_fnames_mode(policy)]; |
|
|
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WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n", |
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inode->i_ino, (inode->i_mode & S_IFMT)); |
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return ERR_PTR(-EINVAL); |
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} |
|
|
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/* Create a symmetric cipher object for the given encryption mode and key */ |
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static struct crypto_skcipher * |
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fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, |
|
const struct inode *inode) |
|
{ |
|
struct crypto_skcipher *tfm; |
|
int err; |
|
|
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tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0); |
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if (IS_ERR(tfm)) { |
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if (PTR_ERR(tfm) == -ENOENT) { |
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fscrypt_warn(inode, |
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"Missing crypto API support for %s (API name: \"%s\")", |
|
mode->friendly_name, mode->cipher_str); |
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return ERR_PTR(-ENOPKG); |
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} |
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fscrypt_err(inode, "Error allocating '%s' transform: %ld", |
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mode->cipher_str, PTR_ERR(tfm)); |
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return tfm; |
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} |
|
if (!xchg(&mode->logged_impl_name, 1)) { |
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/* |
|
* fscrypt performance can vary greatly depending on which |
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* crypto algorithm implementation is used. Help people debug |
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* performance problems by logging the ->cra_driver_name the |
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* first time a mode is used. |
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*/ |
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pr_info("fscrypt: %s using implementation \"%s\"\n", |
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mode->friendly_name, crypto_skcipher_driver_name(tfm)); |
|
} |
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if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) { |
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err = -EINVAL; |
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goto err_free_tfm; |
|
} |
|
crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); |
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err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize); |
|
if (err) |
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goto err_free_tfm; |
|
|
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return tfm; |
|
|
|
err_free_tfm: |
|
crypto_free_skcipher(tfm); |
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return ERR_PTR(err); |
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} |
|
|
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/* |
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* Prepare the crypto transform object or blk-crypto key in @prep_key, given the |
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* raw key, encryption mode, and flag indicating which encryption implementation |
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* (fs-layer or blk-crypto) will be used. |
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*/ |
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int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, |
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const u8 *raw_key, const struct fscrypt_info *ci) |
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{ |
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struct crypto_skcipher *tfm; |
|
|
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if (fscrypt_using_inline_encryption(ci)) |
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return fscrypt_prepare_inline_crypt_key(prep_key, raw_key, ci); |
|
|
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tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode); |
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if (IS_ERR(tfm)) |
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return PTR_ERR(tfm); |
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/* |
|
* Pairs with the smp_load_acquire() in fscrypt_is_key_prepared(). |
|
* I.e., here we publish ->tfm with a RELEASE barrier so that |
|
* concurrent tasks can ACQUIRE it. Note that this concurrency is only |
|
* possible for per-mode keys, not for per-file keys. |
|
*/ |
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smp_store_release(&prep_key->tfm, tfm); |
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return 0; |
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} |
|
|
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/* Destroy a crypto transform object and/or blk-crypto key. */ |
|
void fscrypt_destroy_prepared_key(struct fscrypt_prepared_key *prep_key) |
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{ |
|
crypto_free_skcipher(prep_key->tfm); |
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fscrypt_destroy_inline_crypt_key(prep_key); |
|
} |
|
|
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/* Given a per-file encryption key, set up the file's crypto transform object */ |
|
int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key) |
|
{ |
|
ci->ci_owns_key = true; |
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return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci); |
|
} |
|
|
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static int setup_per_mode_enc_key(struct fscrypt_info *ci, |
|
struct fscrypt_master_key *mk, |
|
struct fscrypt_prepared_key *keys, |
|
u8 hkdf_context, bool include_fs_uuid) |
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{ |
|
const struct inode *inode = ci->ci_inode; |
|
const struct super_block *sb = inode->i_sb; |
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struct fscrypt_mode *mode = ci->ci_mode; |
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const u8 mode_num = mode - fscrypt_modes; |
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struct fscrypt_prepared_key *prep_key; |
|
u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; |
|
u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; |
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unsigned int hkdf_infolen = 0; |
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int err; |
|
|
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if (WARN_ON(mode_num > FSCRYPT_MODE_MAX)) |
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return -EINVAL; |
|
|
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prep_key = &keys[mode_num]; |
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if (fscrypt_is_key_prepared(prep_key, ci)) { |
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ci->ci_enc_key = *prep_key; |
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return 0; |
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} |
|
|
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mutex_lock(&fscrypt_mode_key_setup_mutex); |
|
|
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if (fscrypt_is_key_prepared(prep_key, ci)) |
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goto done_unlock; |
|
|
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BUILD_BUG_ON(sizeof(mode_num) != 1); |
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BUILD_BUG_ON(sizeof(sb->s_uuid) != 16); |
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BUILD_BUG_ON(sizeof(hkdf_info) != 17); |
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hkdf_info[hkdf_infolen++] = mode_num; |
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if (include_fs_uuid) { |
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memcpy(&hkdf_info[hkdf_infolen], &sb->s_uuid, |
|
sizeof(sb->s_uuid)); |
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hkdf_infolen += sizeof(sb->s_uuid); |
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} |
|
err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, |
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hkdf_context, hkdf_info, hkdf_infolen, |
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mode_key, mode->keysize); |
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if (err) |
|
goto out_unlock; |
|
err = fscrypt_prepare_key(prep_key, mode_key, ci); |
|
memzero_explicit(mode_key, mode->keysize); |
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if (err) |
|
goto out_unlock; |
|
done_unlock: |
|
ci->ci_enc_key = *prep_key; |
|
err = 0; |
|
out_unlock: |
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mutex_unlock(&fscrypt_mode_key_setup_mutex); |
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return err; |
|
} |
|
|
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int fscrypt_derive_dirhash_key(struct fscrypt_info *ci, |
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const struct fscrypt_master_key *mk) |
|
{ |
|
int err; |
|
|
|
err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, HKDF_CONTEXT_DIRHASH_KEY, |
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ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE, |
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(u8 *)&ci->ci_dirhash_key, |
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sizeof(ci->ci_dirhash_key)); |
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if (err) |
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return err; |
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ci->ci_dirhash_key_initialized = true; |
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return 0; |
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} |
|
|
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void fscrypt_hash_inode_number(struct fscrypt_info *ci, |
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const struct fscrypt_master_key *mk) |
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{ |
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WARN_ON(ci->ci_inode->i_ino == 0); |
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WARN_ON(!mk->mk_ino_hash_key_initialized); |
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|
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ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino, |
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&mk->mk_ino_hash_key); |
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} |
|
|
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static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci, |
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struct fscrypt_master_key *mk) |
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{ |
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int err; |
|
|
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err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys, |
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HKDF_CONTEXT_IV_INO_LBLK_32_KEY, true); |
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if (err) |
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return err; |
|
|
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/* pairs with smp_store_release() below */ |
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if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) { |
|
|
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mutex_lock(&fscrypt_mode_key_setup_mutex); |
|
|
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if (mk->mk_ino_hash_key_initialized) |
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goto unlock; |
|
|
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err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, |
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HKDF_CONTEXT_INODE_HASH_KEY, NULL, 0, |
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(u8 *)&mk->mk_ino_hash_key, |
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sizeof(mk->mk_ino_hash_key)); |
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if (err) |
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goto unlock; |
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/* pairs with smp_load_acquire() above */ |
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smp_store_release(&mk->mk_ino_hash_key_initialized, true); |
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unlock: |
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mutex_unlock(&fscrypt_mode_key_setup_mutex); |
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if (err) |
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return err; |
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} |
|
|
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/* |
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* New inodes may not have an inode number assigned yet. |
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* Hashing their inode number is delayed until later. |
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*/ |
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if (ci->ci_inode->i_ino) |
|
fscrypt_hash_inode_number(ci, mk); |
|
return 0; |
|
} |
|
|
|
static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci, |
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struct fscrypt_master_key *mk, |
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bool need_dirhash_key) |
|
{ |
|
int err; |
|
|
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if (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) { |
|
/* |
|
* DIRECT_KEY: instead of deriving per-file encryption keys, the |
|
* per-file nonce will be included in all the IVs. But unlike |
|
* v1 policies, for v2 policies in this case we don't encrypt |
|
* with the master key directly but rather derive a per-mode |
|
* encryption key. This ensures that the master key is |
|
* consistently used only for HKDF, avoiding key reuse issues. |
|
*/ |
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err = setup_per_mode_enc_key(ci, mk, mk->mk_direct_keys, |
|
HKDF_CONTEXT_DIRECT_KEY, false); |
|
} else if (ci->ci_policy.v2.flags & |
|
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) { |
|
/* |
|
* IV_INO_LBLK_64: encryption keys are derived from (master_key, |
|
* mode_num, filesystem_uuid), and inode number is included in |
|
* the IVs. This format is optimized for use with inline |
|
* encryption hardware compliant with the UFS standard. |
|
*/ |
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err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_64_keys, |
|
HKDF_CONTEXT_IV_INO_LBLK_64_KEY, |
|
true); |
|
} else if (ci->ci_policy.v2.flags & |
|
FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) { |
|
err = fscrypt_setup_iv_ino_lblk_32_key(ci, mk); |
|
} else { |
|
u8 derived_key[FSCRYPT_MAX_KEY_SIZE]; |
|
|
|
err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, |
|
HKDF_CONTEXT_PER_FILE_ENC_KEY, |
|
ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE, |
|
derived_key, ci->ci_mode->keysize); |
|
if (err) |
|
return err; |
|
|
|
err = fscrypt_set_per_file_enc_key(ci, derived_key); |
|
memzero_explicit(derived_key, ci->ci_mode->keysize); |
|
} |
|
if (err) |
|
return err; |
|
|
|
/* Derive a secret dirhash key for directories that need it. */ |
|
if (need_dirhash_key) { |
|
err = fscrypt_derive_dirhash_key(ci, mk); |
|
if (err) |
|
return err; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Find the master key, then set up the inode's actual encryption key. |
|
* |
|
* If the master key is found in the filesystem-level keyring, then the |
|
* corresponding 'struct key' is returned in *master_key_ret with its semaphore |
|
* read-locked. This is needed to ensure that only one task links the |
|
* fscrypt_info into ->mk_decrypted_inodes (as multiple tasks may race to create |
|
* an fscrypt_info for the same inode), and to synchronize the master key being |
|
* removed with a new inode starting to use it. |
|
*/ |
|
static int setup_file_encryption_key(struct fscrypt_info *ci, |
|
bool need_dirhash_key, |
|
struct key **master_key_ret) |
|
{ |
|
struct key *key; |
|
struct fscrypt_master_key *mk = NULL; |
|
struct fscrypt_key_specifier mk_spec; |
|
int err; |
|
|
|
err = fscrypt_select_encryption_impl(ci); |
|
if (err) |
|
return err; |
|
|
|
switch (ci->ci_policy.version) { |
|
case FSCRYPT_POLICY_V1: |
|
mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR; |
|
memcpy(mk_spec.u.descriptor, |
|
ci->ci_policy.v1.master_key_descriptor, |
|
FSCRYPT_KEY_DESCRIPTOR_SIZE); |
|
break; |
|
case FSCRYPT_POLICY_V2: |
|
mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER; |
|
memcpy(mk_spec.u.identifier, |
|
ci->ci_policy.v2.master_key_identifier, |
|
FSCRYPT_KEY_IDENTIFIER_SIZE); |
|
break; |
|
default: |
|
WARN_ON(1); |
|
return -EINVAL; |
|
} |
|
|
|
key = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec); |
|
if (IS_ERR(key)) { |
|
if (key != ERR_PTR(-ENOKEY) || |
|
ci->ci_policy.version != FSCRYPT_POLICY_V1) |
|
return PTR_ERR(key); |
|
|
|
/* |
|
* As a legacy fallback for v1 policies, search for the key in |
|
* the current task's subscribed keyrings too. Don't move this |
|
* to before the search of ->s_master_keys, since users |
|
* shouldn't be able to override filesystem-level keys. |
|
*/ |
|
return fscrypt_setup_v1_file_key_via_subscribed_keyrings(ci); |
|
} |
|
|
|
mk = key->payload.data[0]; |
|
down_read(&key->sem); |
|
|
|
/* Has the secret been removed (via FS_IOC_REMOVE_ENCRYPTION_KEY)? */ |
|
if (!is_master_key_secret_present(&mk->mk_secret)) { |
|
err = -ENOKEY; |
|
goto out_release_key; |
|
} |
|
|
|
/* |
|
* Require that the master key be at least as long as the derived key. |
|
* Otherwise, the derived key cannot possibly contain as much entropy as |
|
* that required by the encryption mode it will be used for. For v1 |
|
* policies it's also required for the KDF to work at all. |
|
*/ |
|
if (mk->mk_secret.size < ci->ci_mode->keysize) { |
|
fscrypt_warn(NULL, |
|
"key with %s %*phN is too short (got %u bytes, need %u+ bytes)", |
|
master_key_spec_type(&mk_spec), |
|
master_key_spec_len(&mk_spec), (u8 *)&mk_spec.u, |
|
mk->mk_secret.size, ci->ci_mode->keysize); |
|
err = -ENOKEY; |
|
goto out_release_key; |
|
} |
|
|
|
switch (ci->ci_policy.version) { |
|
case FSCRYPT_POLICY_V1: |
|
err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw); |
|
break; |
|
case FSCRYPT_POLICY_V2: |
|
err = fscrypt_setup_v2_file_key(ci, mk, need_dirhash_key); |
|
break; |
|
default: |
|
WARN_ON(1); |
|
err = -EINVAL; |
|
break; |
|
} |
|
if (err) |
|
goto out_release_key; |
|
|
|
*master_key_ret = key; |
|
return 0; |
|
|
|
out_release_key: |
|
up_read(&key->sem); |
|
key_put(key); |
|
return err; |
|
} |
|
|
|
static void put_crypt_info(struct fscrypt_info *ci) |
|
{ |
|
struct key *key; |
|
|
|
if (!ci) |
|
return; |
|
|
|
if (ci->ci_direct_key) |
|
fscrypt_put_direct_key(ci->ci_direct_key); |
|
else if (ci->ci_owns_key) |
|
fscrypt_destroy_prepared_key(&ci->ci_enc_key); |
|
|
|
key = ci->ci_master_key; |
|
if (key) { |
|
struct fscrypt_master_key *mk = key->payload.data[0]; |
|
|
|
/* |
|
* Remove this inode from the list of inodes that were unlocked |
|
* with the master key. |
|
* |
|
* In addition, if we're removing the last inode from a key that |
|
* already had its secret removed, invalidate the key so that it |
|
* gets removed from ->s_master_keys. |
|
*/ |
|
spin_lock(&mk->mk_decrypted_inodes_lock); |
|
list_del(&ci->ci_master_key_link); |
|
spin_unlock(&mk->mk_decrypted_inodes_lock); |
|
if (refcount_dec_and_test(&mk->mk_refcount)) |
|
key_invalidate(key); |
|
key_put(key); |
|
} |
|
memzero_explicit(ci, sizeof(*ci)); |
|
kmem_cache_free(fscrypt_info_cachep, ci); |
|
} |
|
|
|
static int |
|
fscrypt_setup_encryption_info(struct inode *inode, |
|
const union fscrypt_policy *policy, |
|
const u8 nonce[FSCRYPT_FILE_NONCE_SIZE], |
|
bool need_dirhash_key) |
|
{ |
|
struct fscrypt_info *crypt_info; |
|
struct fscrypt_mode *mode; |
|
struct key *master_key = NULL; |
|
int res; |
|
|
|
res = fscrypt_initialize(inode->i_sb->s_cop->flags); |
|
if (res) |
|
return res; |
|
|
|
crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL); |
|
if (!crypt_info) |
|
return -ENOMEM; |
|
|
|
crypt_info->ci_inode = inode; |
|
crypt_info->ci_policy = *policy; |
|
memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE); |
|
|
|
mode = select_encryption_mode(&crypt_info->ci_policy, inode); |
|
if (IS_ERR(mode)) { |
|
res = PTR_ERR(mode); |
|
goto out; |
|
} |
|
WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE); |
|
crypt_info->ci_mode = mode; |
|
|
|
res = setup_file_encryption_key(crypt_info, need_dirhash_key, |
|
&master_key); |
|
if (res) |
|
goto out; |
|
|
|
/* |
|
* For existing inodes, multiple tasks may race to set ->i_crypt_info. |
|
* So use cmpxchg_release(). This pairs with the smp_load_acquire() in |
|
* fscrypt_get_info(). I.e., here we publish ->i_crypt_info with a |
|
* RELEASE barrier so that other tasks can ACQUIRE it. |
|
*/ |
|
if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) { |
|
/* |
|
* We won the race and set ->i_crypt_info to our crypt_info. |
|
* Now link it into the master key's inode list. |
|
*/ |
|
if (master_key) { |
|
struct fscrypt_master_key *mk = |
|
master_key->payload.data[0]; |
|
|
|
refcount_inc(&mk->mk_refcount); |
|
crypt_info->ci_master_key = key_get(master_key); |
|
spin_lock(&mk->mk_decrypted_inodes_lock); |
|
list_add(&crypt_info->ci_master_key_link, |
|
&mk->mk_decrypted_inodes); |
|
spin_unlock(&mk->mk_decrypted_inodes_lock); |
|
} |
|
crypt_info = NULL; |
|
} |
|
res = 0; |
|
out: |
|
if (master_key) { |
|
up_read(&master_key->sem); |
|
key_put(master_key); |
|
} |
|
put_crypt_info(crypt_info); |
|
return res; |
|
} |
|
|
|
/** |
|
* fscrypt_get_encryption_info() - set up an inode's encryption key |
|
* @inode: the inode to set up the key for. Must be encrypted. |
|
* @allow_unsupported: if %true, treat an unsupported encryption policy (or |
|
* unrecognized encryption context) the same way as the key |
|
* being unavailable, instead of returning an error. Use |
|
* %false unless the operation being performed is needed in |
|
* order for files (or directories) to be deleted. |
|
* |
|
* Set up ->i_crypt_info, if it hasn't already been done. |
|
* |
|
* Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe. So |
|
* generally this shouldn't be called from within a filesystem transaction. |
|
* |
|
* Return: 0 if ->i_crypt_info was set or was already set, *or* if the |
|
* encryption key is unavailable. (Use fscrypt_has_encryption_key() to |
|
* distinguish these cases.) Also can return another -errno code. |
|
*/ |
|
int fscrypt_get_encryption_info(struct inode *inode, bool allow_unsupported) |
|
{ |
|
int res; |
|
union fscrypt_context ctx; |
|
union fscrypt_policy policy; |
|
|
|
if (fscrypt_has_encryption_key(inode)) |
|
return 0; |
|
|
|
res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); |
|
if (res < 0) { |
|
if (res == -ERANGE && allow_unsupported) |
|
return 0; |
|
fscrypt_warn(inode, "Error %d getting encryption context", res); |
|
return res; |
|
} |
|
|
|
res = fscrypt_policy_from_context(&policy, &ctx, res); |
|
if (res) { |
|
if (allow_unsupported) |
|
return 0; |
|
fscrypt_warn(inode, |
|
"Unrecognized or corrupt encryption context"); |
|
return res; |
|
} |
|
|
|
if (!fscrypt_supported_policy(&policy, inode)) { |
|
if (allow_unsupported) |
|
return 0; |
|
return -EINVAL; |
|
} |
|
|
|
res = fscrypt_setup_encryption_info(inode, &policy, |
|
fscrypt_context_nonce(&ctx), |
|
IS_CASEFOLDED(inode) && |
|
S_ISDIR(inode->i_mode)); |
|
|
|
if (res == -ENOPKG && allow_unsupported) /* Algorithm unavailable? */ |
|
res = 0; |
|
if (res == -ENOKEY) |
|
res = 0; |
|
return res; |
|
} |
|
|
|
/** |
|
* fscrypt_prepare_new_inode() - prepare to create a new inode in a directory |
|
* @dir: a possibly-encrypted directory |
|
* @inode: the new inode. ->i_mode must be set already. |
|
* ->i_ino doesn't need to be set yet. |
|
* @encrypt_ret: (output) set to %true if the new inode will be encrypted |
|
* |
|
* If the directory is encrypted, set up its ->i_crypt_info in preparation for |
|
* encrypting the name of the new file. Also, if the new inode will be |
|
* encrypted, set up its ->i_crypt_info and set *encrypt_ret=true. |
|
* |
|
* This isn't %GFP_NOFS-safe, and therefore it should be called before starting |
|
* any filesystem transaction to create the inode. For this reason, ->i_ino |
|
* isn't required to be set yet, as the filesystem may not have set it yet. |
|
* |
|
* This doesn't persist the new inode's encryption context. That still needs to |
|
* be done later by calling fscrypt_set_context(). |
|
* |
|
* Return: 0 on success, -ENOKEY if the encryption key is missing, or another |
|
* -errno code |
|
*/ |
|
int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode, |
|
bool *encrypt_ret) |
|
{ |
|
const union fscrypt_policy *policy; |
|
u8 nonce[FSCRYPT_FILE_NONCE_SIZE]; |
|
|
|
policy = fscrypt_policy_to_inherit(dir); |
|
if (policy == NULL) |
|
return 0; |
|
if (IS_ERR(policy)) |
|
return PTR_ERR(policy); |
|
|
|
if (WARN_ON_ONCE(inode->i_mode == 0)) |
|
return -EINVAL; |
|
|
|
/* |
|
* Only regular files, directories, and symlinks are encrypted. |
|
* Special files like device nodes and named pipes aren't. |
|
*/ |
|
if (!S_ISREG(inode->i_mode) && |
|
!S_ISDIR(inode->i_mode) && |
|
!S_ISLNK(inode->i_mode)) |
|
return 0; |
|
|
|
*encrypt_ret = true; |
|
|
|
get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE); |
|
return fscrypt_setup_encryption_info(inode, policy, nonce, |
|
IS_CASEFOLDED(dir) && |
|
S_ISDIR(inode->i_mode)); |
|
} |
|
EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode); |
|
|
|
/** |
|
* fscrypt_put_encryption_info() - free most of an inode's fscrypt data |
|
* @inode: an inode being evicted |
|
* |
|
* Free the inode's fscrypt_info. Filesystems must call this when the inode is |
|
* being evicted. An RCU grace period need not have elapsed yet. |
|
*/ |
|
void fscrypt_put_encryption_info(struct inode *inode) |
|
{ |
|
put_crypt_info(inode->i_crypt_info); |
|
inode->i_crypt_info = NULL; |
|
} |
|
EXPORT_SYMBOL(fscrypt_put_encryption_info); |
|
|
|
/** |
|
* fscrypt_free_inode() - free an inode's fscrypt data requiring RCU delay |
|
* @inode: an inode being freed |
|
* |
|
* Free the inode's cached decrypted symlink target, if any. Filesystems must |
|
* call this after an RCU grace period, just before they free the inode. |
|
*/ |
|
void fscrypt_free_inode(struct inode *inode) |
|
{ |
|
if (IS_ENCRYPTED(inode) && S_ISLNK(inode->i_mode)) { |
|
kfree(inode->i_link); |
|
inode->i_link = NULL; |
|
} |
|
} |
|
EXPORT_SYMBOL(fscrypt_free_inode); |
|
|
|
/** |
|
* fscrypt_drop_inode() - check whether the inode's master key has been removed |
|
* @inode: an inode being considered for eviction |
|
* |
|
* Filesystems supporting fscrypt must call this from their ->drop_inode() |
|
* method so that encrypted inodes are evicted as soon as they're no longer in |
|
* use and their master key has been removed. |
|
* |
|
* Return: 1 if fscrypt wants the inode to be evicted now, otherwise 0 |
|
*/ |
|
int fscrypt_drop_inode(struct inode *inode) |
|
{ |
|
const struct fscrypt_info *ci = fscrypt_get_info(inode); |
|
const struct fscrypt_master_key *mk; |
|
|
|
/* |
|
* If ci is NULL, then the inode doesn't have an encryption key set up |
|
* so it's irrelevant. If ci_master_key is NULL, then the master key |
|
* was provided via the legacy mechanism of the process-subscribed |
|
* keyrings, so we don't know whether it's been removed or not. |
|
*/ |
|
if (!ci || !ci->ci_master_key) |
|
return 0; |
|
mk = ci->ci_master_key->payload.data[0]; |
|
|
|
/* |
|
* With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes |
|
* protected by the key were cleaned by sync_filesystem(). But if |
|
* userspace is still using the files, inodes can be dirtied between |
|
* then and now. We mustn't lose any writes, so skip dirty inodes here. |
|
*/ |
|
if (inode->i_state & I_DIRTY_ALL) |
|
return 0; |
|
|
|
/* |
|
* Note: since we aren't holding the key semaphore, the result here can |
|
* immediately become outdated. But there's no correctness problem with |
|
* unnecessarily evicting. Nor is there a correctness problem with not |
|
* evicting while iput() is racing with the key being removed, since |
|
* then the thread removing the key will either evict the inode itself |
|
* or will correctly detect that it wasn't evicted due to the race. |
|
*/ |
|
return !is_master_key_secret_present(&mk->mk_secret); |
|
} |
|
EXPORT_SYMBOL_GPL(fscrypt_drop_inode);
|
|
|