| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Eric Biggers | 2381 | 79.13% | 62 | 73.81% |
| Jaegeuk Kim | 237 | 7.88% | 9 | 10.71% |
| Daniel Walter | 130 | 4.32% | 1 | 1.19% |
| Satya Tangirala | 123 | 4.09% | 1 | 1.19% |
| Daniel Rosenberg | 73 | 2.43% | 1 | 1.19% |
| Josef Whiter | 18 | 0.60% | 1 | 1.19% |
| Tianjia Zhang | 17 | 0.56% | 1 | 1.19% |
| Nathan Huckleberry | 10 | 0.33% | 1 | 1.19% |
| Artem B. Bityutskiy | 6 | 0.20% | 2 | 2.38% |
| David Gstir | 5 | 0.17% | 1 | 1.19% |
| Chao Yu | 5 | 0.17% | 1 | 1.19% |
| Xiubo Li | 2 | 0.07% | 1 | 1.19% |
| Theodore Y. Ts'o | 1 | 0.03% | 1 | 1.19% |
| Greg Kroah-Hartman | 1 | 0.03% | 1 | 1.19% |
| Total | 3009 | 84 |
// SPDX-License-Identifier: GPL-2.0 /* * Key setup facility for FS encryption support. * * Copyright (C) 2015, Google, Inc. * * Originally written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar. * Heavily modified since then. */ #include <crypto/skcipher.h> #include <linux/random.h> #include "fscrypt_private.h" struct fscrypt_mode fscrypt_modes[] = { [FSCRYPT_MODE_AES_256_XTS] = { .friendly_name = "AES-256-XTS", .cipher_str = "xts(aes)", .keysize = 64, .security_strength = 32, .ivsize = 16, .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_256_XTS, }, [FSCRYPT_MODE_AES_256_CTS] = { .friendly_name = "AES-256-CBC-CTS", .cipher_str = "cts(cbc(aes))", .keysize = 32, .security_strength = 32, .ivsize = 16, }, [FSCRYPT_MODE_AES_128_CBC] = { .friendly_name = "AES-128-CBC-ESSIV", .cipher_str = "essiv(cbc(aes),sha256)", .keysize = 16, .security_strength = 16, .ivsize = 16, .blk_crypto_mode = BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV, }, [FSCRYPT_MODE_AES_128_CTS] = { .friendly_name = "AES-128-CBC-CTS", .cipher_str = "cts(cbc(aes))", .keysize = 16, .security_strength = 16, .ivsize = 16, }, [FSCRYPT_MODE_SM4_XTS] = { .friendly_name = "SM4-XTS", .cipher_str = "xts(sm4)", .keysize = 32, .security_strength = 16, .ivsize = 16, .blk_crypto_mode = BLK_ENCRYPTION_MODE_SM4_XTS, }, [FSCRYPT_MODE_SM4_CTS] = { .friendly_name = "SM4-CBC-CTS", .cipher_str = "cts(cbc(sm4))", .keysize = 16, .security_strength = 16, .ivsize = 16, }, [FSCRYPT_MODE_ADIANTUM] = { .friendly_name = "Adiantum", .cipher_str = "adiantum(xchacha12,aes)", .keysize = 32, .security_strength = 32, .ivsize = 32, .blk_crypto_mode = BLK_ENCRYPTION_MODE_ADIANTUM, }, [FSCRYPT_MODE_AES_256_HCTR2] = { .friendly_name = "AES-256-HCTR2", .cipher_str = "hctr2(aes)", .keysize = 32, .security_strength = 32, .ivsize = 32, }, }; static DEFINE_MUTEX(fscrypt_mode_key_setup_mutex); static struct fscrypt_mode * select_encryption_mode(const union fscrypt_policy *policy, const struct inode *inode) { BUILD_BUG_ON(ARRAY_SIZE(fscrypt_modes) != FSCRYPT_MODE_MAX + 1); if (S_ISREG(inode->i_mode)) return &fscrypt_modes[fscrypt_policy_contents_mode(policy)]; if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) return &fscrypt_modes[fscrypt_policy_fnames_mode(policy)]; WARN_ONCE(1, "fscrypt: filesystem tried to load encryption info for inode %lu, which is not encryptable (file type %d)\n", inode->i_ino, (inode->i_mode & S_IFMT)); return ERR_PTR(-EINVAL); } /* Create a symmetric cipher object for the given encryption mode and key */ static struct crypto_skcipher * fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key, const struct inode *inode) { struct crypto_skcipher *tfm; int err; tfm = crypto_alloc_skcipher(mode->cipher_str, 0, 0); if (IS_ERR(tfm)) { if (PTR_ERR(tfm) == -ENOENT) { fscrypt_warn(inode, "Missing crypto API support for %s (API name: \"%s\")", mode->friendly_name, mode->cipher_str); return ERR_PTR(-ENOPKG); } fscrypt_err(inode, "Error allocating '%s' transform: %ld", mode->cipher_str, PTR_ERR(tfm)); return tfm; } if (!xchg(&mode->logged_cryptoapi_impl, 1)) { /* * fscrypt performance can vary greatly depending on which * crypto algorithm implementation is used. Help people debug * performance problems by logging the ->cra_driver_name the * first time a mode is used. */ pr_info("fscrypt: %s using implementation \"%s\"\n", mode->friendly_name, crypto_skcipher_driver_name(tfm)); } if (WARN_ON_ONCE(crypto_skcipher_ivsize(tfm) != mode->ivsize)) { err = -EINVAL; goto err_free_tfm; } crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize); if (err) goto err_free_tfm; return tfm; err_free_tfm: crypto_free_skcipher(tfm); return ERR_PTR(err); } /* * Prepare the crypto transform object or blk-crypto key in @prep_key, given the * raw key, encryption mode (@ci->ci_mode), flag indicating which encryption * implementation (fs-layer or blk-crypto) will be used (@ci->ci_inlinecrypt), * and IV generation method (@ci->ci_policy.flags). */ int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key, const u8 *raw_key, const struct fscrypt_inode_info *ci) { struct crypto_skcipher *tfm; if (fscrypt_using_inline_encryption(ci)) return fscrypt_prepare_inline_crypt_key(prep_key, raw_key, ci); tfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key, ci->ci_inode); if (IS_ERR(tfm)) return PTR_ERR(tfm); /* * 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. */ smp_store_release(&prep_key->tfm, tfm); return 0; } /* Destroy a crypto transform object and/or blk-crypto key. */ void fscrypt_destroy_prepared_key(struct super_block *sb, struct fscrypt_prepared_key *prep_key) { crypto_free_skcipher(prep_key->tfm); fscrypt_destroy_inline_crypt_key(sb, prep_key); memzero_explicit(prep_key, sizeof(*prep_key)); } /* Given a per-file encryption key, set up the file's crypto transform object */ int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci, const u8 *raw_key) { ci->ci_owns_key = true; return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci); } static int setup_per_mode_enc_key(struct fscrypt_inode_info *ci, struct fscrypt_master_key *mk, struct fscrypt_prepared_key *keys, u8 hkdf_context, bool include_fs_uuid) { const struct inode *inode = ci->ci_inode; const struct super_block *sb = inode->i_sb; struct fscrypt_mode *mode = ci->ci_mode; const u8 mode_num = mode - fscrypt_modes; struct fscrypt_prepared_key *prep_key; u8 mode_key[FSCRYPT_MAX_KEY_SIZE]; u8 hkdf_info[sizeof(mode_num) + sizeof(sb->s_uuid)]; unsigned int hkdf_infolen = 0; int err; if (WARN_ON_ONCE(mode_num > FSCRYPT_MODE_MAX)) return -EINVAL; prep_key = &keys[mode_num]; if (fscrypt_is_key_prepared(prep_key, ci)) { ci->ci_enc_key = *prep_key; return 0; } mutex_lock(&fscrypt_mode_key_setup_mutex); if (fscrypt_is_key_prepared(prep_key, ci)) goto done_unlock; BUILD_BUG_ON(sizeof(mode_num) != 1); BUILD_BUG_ON(sizeof(sb->s_uuid) != 16); BUILD_BUG_ON(sizeof(hkdf_info) != 17); hkdf_info[hkdf_infolen++] = mode_num; if (include_fs_uuid) { memcpy(&hkdf_info[hkdf_infolen], &sb->s_uuid, sizeof(sb->s_uuid)); hkdf_infolen += sizeof(sb->s_uuid); } err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, hkdf_context, hkdf_info, hkdf_infolen, mode_key, mode->keysize); if (err) goto out_unlock; err = fscrypt_prepare_key(prep_key, mode_key, ci); memzero_explicit(mode_key, mode->keysize); if (err) goto out_unlock; done_unlock: ci->ci_enc_key = *prep_key; err = 0; out_unlock: mutex_unlock(&fscrypt_mode_key_setup_mutex); return err; } /* * Derive a SipHash key from the given fscrypt master key and the given * application-specific information string. * * Note that the KDF produces a byte array, but the SipHash APIs expect the key * as a pair of 64-bit words. Therefore, on big endian CPUs we have to do an * endianness swap in order to get the same results as on little endian CPUs. */ static int fscrypt_derive_siphash_key(const struct fscrypt_master_key *mk, u8 context, const u8 *info, unsigned int infolen, siphash_key_t *key) { int err; err = fscrypt_hkdf_expand(&mk->mk_secret.hkdf, context, info, infolen, (u8 *)key, sizeof(*key)); if (err) return err; BUILD_BUG_ON(sizeof(*key) != 16); BUILD_BUG_ON(ARRAY_SIZE(key->key) != 2); le64_to_cpus(&key->key[0]); le64_to_cpus(&key->key[1]); return 0; } int fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci, const struct fscrypt_master_key *mk) { int err; err = fscrypt_derive_siphash_key(mk, HKDF_CONTEXT_DIRHASH_KEY, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE, &ci->ci_dirhash_key); if (err) return err; ci->ci_dirhash_key_initialized = true; return 0; } void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci, const struct fscrypt_master_key *mk) { WARN_ON_ONCE(ci->ci_inode->i_ino == 0); WARN_ON_ONCE(!mk->mk_ino_hash_key_initialized); ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino, &mk->mk_ino_hash_key); } static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_inode_info *ci, struct fscrypt_master_key *mk) { int err; err = setup_per_mode_enc_key(ci, mk, mk->mk_iv_ino_lblk_32_keys, HKDF_CONTEXT_IV_INO_LBLK_32_KEY, true); if (err) return err; /* pairs with smp_store_release() below */ if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) { mutex_lock(&fscrypt_mode_key_setup_mutex); if (mk->mk_ino_hash_key_initialized) goto unlock; err = fscrypt_derive_siphash_key(mk, HKDF_CONTEXT_INODE_HASH_KEY, NULL, 0, &mk->mk_ino_hash_key); if (err) goto unlock; /* pairs with smp_load_acquire() above */ smp_store_release(&mk->mk_ino_hash_key_initialized, true); unlock: mutex_unlock(&fscrypt_mode_key_setup_mutex); if (err) return err; } /* * New inodes may not have an inode number assigned yet. * Hashing their inode number is delayed until later. */ if (ci->ci_inode->i_ino) fscrypt_hash_inode_number(ci, mk); return 0; } static int fscrypt_setup_v2_file_key(struct fscrypt_inode_info *ci, struct fscrypt_master_key *mk, bool need_dirhash_key) { int err; 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. */ 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. */ 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; } /* * Check whether the size of the given master key (@mk) is appropriate for the * encryption settings which a particular file will use (@ci). * * If the file uses a v1 encryption policy, then the master key must be at least * as long as the derived key, as this is a requirement of the v1 KDF. * * Otherwise, the KDF can accept any size key, so we enforce a slightly looser * requirement: we require that the size of the master key be at least the * maximum security strength of any algorithm whose key will be derived from it * (but in practice we only need to consider @ci->ci_mode, since any other * possible subkeys such as DIRHASH and INODE_HASH will never increase the * required key size over @ci->ci_mode). This allows AES-256-XTS keys to be * derived from a 256-bit master key, which is cryptographically sufficient, * rather than requiring a 512-bit master key which is unnecessarily long. (We * still allow 512-bit master keys if the user chooses to use them, though.) */ static bool fscrypt_valid_master_key_size(const struct fscrypt_master_key *mk, const struct fscrypt_inode_info *ci) { unsigned int min_keysize; if (ci->ci_policy.version == FSCRYPT_POLICY_V1) min_keysize = ci->ci_mode->keysize; else min_keysize = ci->ci_mode->security_strength; if (mk->mk_secret.size < min_keysize) { fscrypt_warn(NULL, "key with %s %*phN is too short (got %u bytes, need %u+ bytes)", master_key_spec_type(&mk->mk_spec), master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u, mk->mk_secret.size, min_keysize); return false; } return true; } /* * 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 it is * returned in *mk_ret with its semaphore read-locked. This is needed to ensure * that only one task links the fscrypt_inode_info into ->mk_decrypted_inodes * (as multiple tasks may race to create an fscrypt_inode_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_inode_info *ci, bool need_dirhash_key, struct fscrypt_master_key **mk_ret) { struct super_block *sb = ci->ci_inode->i_sb; struct fscrypt_key_specifier mk_spec; struct fscrypt_master_key *mk; int err; err = fscrypt_select_encryption_impl(ci); if (err) return err; err = fscrypt_policy_to_key_spec(&ci->ci_policy, &mk_spec); if (err) return err; mk = fscrypt_find_master_key(sb, &mk_spec); if (unlikely(!mk)) { const union fscrypt_policy *dummy_policy = fscrypt_get_dummy_policy(sb); /* * Add the test_dummy_encryption key on-demand. In principle, * it should be added at mount time. Do it here instead so that * the individual filesystems don't need to worry about adding * this key at mount time and cleaning up on mount failure. */ if (dummy_policy && fscrypt_policies_equal(dummy_policy, &ci->ci_policy)) { err = fscrypt_add_test_dummy_key(sb, &mk_spec); if (err) return err; mk = fscrypt_find_master_key(sb, &mk_spec); } } if (unlikely(!mk)) { if (ci->ci_policy.version != FSCRYPT_POLICY_V1) return -ENOKEY; /* * 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); } down_read(&mk->mk_sem); if (!mk->mk_present) { /* FS_IOC_REMOVE_ENCRYPTION_KEY has been executed on this key */ err = -ENOKEY; goto out_release_key; } if (!fscrypt_valid_master_key_size(mk, ci)) { 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_ONCE(1); err = -EINVAL; break; } if (err) goto out_release_key; *mk_ret = mk; return 0; out_release_key: up_read(&mk->mk_sem); fscrypt_put_master_key(mk); return err; } static void put_crypt_info(struct fscrypt_inode_info *ci) { struct fscrypt_master_key *mk; 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_inode->i_sb, &ci->ci_enc_key); mk = ci->ci_master_key; if (mk) { /* * 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 an incompletely removed key, then complete the * full removal of the key. */ spin_lock(&mk->mk_decrypted_inodes_lock); list_del(&ci->ci_master_key_link); spin_unlock(&mk->mk_decrypted_inodes_lock); fscrypt_put_master_key_activeref(ci->ci_inode->i_sb, mk); } memzero_explicit(ci, sizeof(*ci)); kmem_cache_free(fscrypt_inode_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_inode_info *crypt_info; struct fscrypt_mode *mode; struct fscrypt_master_key *mk = NULL; int res; res = fscrypt_initialize(inode->i_sb); if (res) return res; crypt_info = kmem_cache_zalloc(fscrypt_inode_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_ONCE(mode->ivsize > FSCRYPT_MAX_IV_SIZE); crypt_info->ci_mode = mode; crypt_info->ci_data_unit_bits = fscrypt_policy_du_bits(&crypt_info->ci_policy, inode); crypt_info->ci_data_units_per_block_bits = inode->i_blkbits - crypt_info->ci_data_unit_bits; res = setup_file_encryption_key(crypt_info, need_dirhash_key, &mk); 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_inode_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 (mk) { crypt_info->ci_master_key = mk; refcount_inc(&mk->mk_active_refs); 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 (mk) { up_read(&mk->mk_sem); fscrypt_put_master_key(mk); } 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 and ->i_blkbits 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_blkbits == 0)) return -EINVAL; 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_inode_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_inode_info *ci = fscrypt_get_inode_info(inode); /* * 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; /* * 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; /* * We can't take ->mk_sem here, since this runs in atomic context. * Therefore, ->mk_present can change concurrently, and our result may * 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 !READ_ONCE(ci->ci_master_key->mk_present); } EXPORT_SYMBOL_GPL(fscrypt_drop_inode);
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