0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 1) // SPDX-License-Identifier: GPL-2.0
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 2) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 3) * Key setup for v1 encryption policies
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 4) *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 5) * Copyright 2015, 2019 Google LLC
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 6) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 7)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 8) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 9) * This file implements compatibility functions for the original encryption
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 10) * policy version ("v1"), including:
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 11) *
f592efe735a29 (Eric Biggers 2020-01-20 14:31:58 -0800 12) * - Deriving per-file encryption keys using the AES-128-ECB based KDF
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 13) * (rather than the new method of using HKDF-SHA512)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 14) *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 15) * - Retrieving fscrypt master keys from process-subscribed keyrings
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 16) * (rather than the new method of using a filesystem-level keyring)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 17) *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 18) * - Handling policies with the DIRECT_KEY flag set using a master key table
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 19) * (rather than the new method of implementing DIRECT_KEY with per-mode keys
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 20) * managed alongside the master keys in the filesystem-level keyring)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 21) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 22)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 23) #include <crypto/algapi.h>
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 24) #include <crypto/skcipher.h>
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 25) #include <keys/user-type.h>
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 26) #include <linux/hashtable.h>
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 27) #include <linux/scatterlist.h>
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 28)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 29) #include "fscrypt_private.h"
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 30)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 31) /* Table of keys referenced by DIRECT_KEY policies */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 32) static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 33) static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 34)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 35) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 36) * v1 key derivation function. This generates the derived key by encrypting the
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 37) * master key with AES-128-ECB using the nonce as the AES key. This provides a
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 38) * unique derived key with sufficient entropy for each inode. However, it's
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 39) * nonstandard, non-extensible, doesn't evenly distribute the entropy from the
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 40) * master key, and is trivially reversible: an attacker who compromises a
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 41) * derived key can "decrypt" it to get back to the master key, then derive any
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 42) * other key. For all new code, use HKDF instead.
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 43) *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 44) * The master key must be at least as long as the derived key. If the master
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 45) * key is longer, then only the first 'derived_keysize' bytes are used.
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 46) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 47) static int derive_key_aes(const u8 *master_key,
1d6217a4f9905 (Eric Biggers 2020-07-08 14:57:22 -0700 48) const u8 nonce[FSCRYPT_FILE_NONCE_SIZE],
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 49) u8 *derived_key, unsigned int derived_keysize)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 50) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 51) int res = 0;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 52) struct skcipher_request *req = NULL;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 53) DECLARE_CRYPTO_WAIT(wait);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 54) struct scatterlist src_sg, dst_sg;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 55) struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 56)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 57) if (IS_ERR(tfm)) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 58) res = PTR_ERR(tfm);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 59) tfm = NULL;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 60) goto out;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 61) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 62) crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
9dad5feb49a5c (Eric Biggers 2020-09-16 21:11:32 -0700 63) req = skcipher_request_alloc(tfm, GFP_KERNEL);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 64) if (!req) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 65) res = -ENOMEM;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 66) goto out;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 67) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 68) skcipher_request_set_callback(req,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 69) CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 70) crypto_req_done, &wait);
1d6217a4f9905 (Eric Biggers 2020-07-08 14:57:22 -0700 71) res = crypto_skcipher_setkey(tfm, nonce, FSCRYPT_FILE_NONCE_SIZE);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 72) if (res < 0)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 73) goto out;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 74)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 75) sg_init_one(&src_sg, master_key, derived_keysize);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 76) sg_init_one(&dst_sg, derived_key, derived_keysize);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 77) skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 78) NULL);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 79) res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 80) out:
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 81) skcipher_request_free(req);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 82) crypto_free_skcipher(tfm);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 83) return res;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 84) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 85)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 86) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 87) * Search the current task's subscribed keyrings for a "logon" key with
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 88) * description prefix:descriptor, and if found acquire a read lock on it and
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 89) * return a pointer to its validated payload in *payload_ret.
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 90) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 91) static struct key *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 92) find_and_lock_process_key(const char *prefix,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 93) const u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE],
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 94) unsigned int min_keysize,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 95) const struct fscrypt_key **payload_ret)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 96) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 97) char *description;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 98) struct key *key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 99) const struct user_key_payload *ukp;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 100) const struct fscrypt_key *payload;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 101)
9dad5feb49a5c (Eric Biggers 2020-09-16 21:11:32 -0700 102) description = kasprintf(GFP_KERNEL, "%s%*phN", prefix,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 103) FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 104) if (!description)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 105) return ERR_PTR(-ENOMEM);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 106)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 107) key = request_key(&key_type_logon, description, NULL);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 108) kfree(description);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 109) if (IS_ERR(key))
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 110) return key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 111)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 112) down_read(&key->sem);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 113) ukp = user_key_payload_locked(key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 114)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 115) if (!ukp) /* was the key revoked before we acquired its semaphore? */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 116) goto invalid;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 117)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 118) payload = (const struct fscrypt_key *)ukp->data;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 119)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 120) if (ukp->datalen != sizeof(struct fscrypt_key) ||
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 121) payload->size < 1 || payload->size > FSCRYPT_MAX_KEY_SIZE) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 122) fscrypt_warn(NULL,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 123) "key with description '%s' has invalid payload",
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 124) key->description);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 125) goto invalid;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 126) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 127)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 128) if (payload->size < min_keysize) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 129) fscrypt_warn(NULL,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 130) "key with description '%s' is too short (got %u bytes, need %u+ bytes)",
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 131) key->description, payload->size, min_keysize);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 132) goto invalid;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 133) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 134)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 135) *payload_ret = payload;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 136) return key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 137)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 138) invalid:
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 139) up_read(&key->sem);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 140) key_put(key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 141) return ERR_PTR(-ENOKEY);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 142) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 143)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 144) /* Master key referenced by DIRECT_KEY policy */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 145) struct fscrypt_direct_key {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 146) struct hlist_node dk_node;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 147) refcount_t dk_refcount;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 148) const struct fscrypt_mode *dk_mode;
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 149) struct fscrypt_prepared_key dk_key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 150) u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 151) u8 dk_raw[FSCRYPT_MAX_KEY_SIZE];
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 152) };
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 153)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 154) static void free_direct_key(struct fscrypt_direct_key *dk)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 155) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 156) if (dk) {
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 157) fscrypt_destroy_prepared_key(&dk->dk_key);
453431a54934d (Waiman Long 2020-08-06 23:18:13 -0700 158) kfree_sensitive(dk);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 159) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 160) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 161)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 162) void fscrypt_put_direct_key(struct fscrypt_direct_key *dk)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 163) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 164) if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 165) return;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 166) hash_del(&dk->dk_node);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 167) spin_unlock(&fscrypt_direct_keys_lock);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 168)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 169) free_direct_key(dk);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 170) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 171)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 172) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 173) * Find/insert the given key into the fscrypt_direct_keys table. If found, it
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 174) * is returned with elevated refcount, and 'to_insert' is freed if non-NULL. If
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 175) * not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 176) * NULL is returned.
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 177) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 178) static struct fscrypt_direct_key *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 179) find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 180) const u8 *raw_key, const struct fscrypt_info *ci)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 181) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 182) unsigned long hash_key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 183) struct fscrypt_direct_key *dk;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 184)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 185) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 186) * Careful: to avoid potentially leaking secret key bytes via timing
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 187) * information, we must key the hash table by descriptor rather than by
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 188) * raw key, and use crypto_memneq() when comparing raw keys.
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 189) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 190)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 191) BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 192) memcpy(&hash_key, ci->ci_policy.v1.master_key_descriptor,
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 193) sizeof(hash_key));
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 194)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 195) spin_lock(&fscrypt_direct_keys_lock);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 196) hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 197) if (memcmp(ci->ci_policy.v1.master_key_descriptor,
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 198) dk->dk_descriptor, FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 199) continue;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 200) if (ci->ci_mode != dk->dk_mode)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 201) continue;
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 202) if (!fscrypt_is_key_prepared(&dk->dk_key, ci))
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 203) continue;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 204) if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 205) continue;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 206) /* using existing tfm with same (descriptor, mode, raw_key) */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 207) refcount_inc(&dk->dk_refcount);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 208) spin_unlock(&fscrypt_direct_keys_lock);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 209) free_direct_key(to_insert);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 210) return dk;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 211) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 212) if (to_insert)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 213) hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 214) spin_unlock(&fscrypt_direct_keys_lock);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 215) return to_insert;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 216) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 217)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 218) /* Prepare to encrypt directly using the master key in the given mode */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 219) static struct fscrypt_direct_key *
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 220) fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 221) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 222) struct fscrypt_direct_key *dk;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 223) int err;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 224)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 225) /* Is there already a tfm for this key? */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 226) dk = find_or_insert_direct_key(NULL, raw_key, ci);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 227) if (dk)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 228) return dk;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 229)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 230) /* Nope, allocate one. */
9dad5feb49a5c (Eric Biggers 2020-09-16 21:11:32 -0700 231) dk = kzalloc(sizeof(*dk), GFP_KERNEL);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 232) if (!dk)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 233) return ERR_PTR(-ENOMEM);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 234) refcount_set(&dk->dk_refcount, 1);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 235) dk->dk_mode = ci->ci_mode;
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 236) err = fscrypt_prepare_key(&dk->dk_key, raw_key, ci);
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 237) if (err)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 238) goto err_free_dk;
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 239) memcpy(dk->dk_descriptor, ci->ci_policy.v1.master_key_descriptor,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 240) FSCRYPT_KEY_DESCRIPTOR_SIZE);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 241) memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 242)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 243) return find_or_insert_direct_key(dk, raw_key, ci);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 244)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 245) err_free_dk:
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 246) free_direct_key(dk);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 247) return ERR_PTR(err);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 248) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 249)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 250) /* v1 policy, DIRECT_KEY: use the master key directly */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 251) static int setup_v1_file_key_direct(struct fscrypt_info *ci,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 252) const u8 *raw_master_key)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 253) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 254) struct fscrypt_direct_key *dk;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 255)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 256) dk = fscrypt_get_direct_key(ci, raw_master_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 257) if (IS_ERR(dk))
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 258) return PTR_ERR(dk);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 259) ci->ci_direct_key = dk;
5fee36095cda4 (Satya Tangirala 2020-07-02 01:56:05 +0000 260) ci->ci_enc_key = dk->dk_key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 261) return 0;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 262) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 263)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 264) /* v1 policy, !DIRECT_KEY: derive the file's encryption key */
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 265) static int setup_v1_file_key_derived(struct fscrypt_info *ci,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 266) const u8 *raw_master_key)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 267) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 268) u8 *derived_key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 269) int err;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 270)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 271) /*
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 272) * This cannot be a stack buffer because it will be passed to the
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 273) * scatterlist crypto API during derive_key_aes().
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 274) */
9dad5feb49a5c (Eric Biggers 2020-09-16 21:11:32 -0700 275) derived_key = kmalloc(ci->ci_mode->keysize, GFP_KERNEL);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 276) if (!derived_key)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 277) return -ENOMEM;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 278)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 279) err = derive_key_aes(raw_master_key, ci->ci_nonce,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 280) derived_key, ci->ci_mode->keysize);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 281) if (err)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 282) goto out;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 283)
f592efe735a29 (Eric Biggers 2020-01-20 14:31:58 -0800 284) err = fscrypt_set_per_file_enc_key(ci, derived_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 285) out:
453431a54934d (Waiman Long 2020-08-06 23:18:13 -0700 286) kfree_sensitive(derived_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 287) return err;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 288) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 289)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 290) int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, const u8 *raw_master_key)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 291) {
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 292) if (ci->ci_policy.v1.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 293) return setup_v1_file_key_direct(ci, raw_master_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 294) else
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 295) return setup_v1_file_key_derived(ci, raw_master_key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 296) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 297)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 298) int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 299) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 300) struct key *key;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 301) const struct fscrypt_key *payload;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 302) int err;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 303)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 304) key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 305) ci->ci_policy.v1.master_key_descriptor,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 306) ci->ci_mode->keysize, &payload);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 307) if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 308) key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
5dae460c2292d (Eric Biggers 2019-08-04 19:35:47 -0700 309) ci->ci_policy.v1.master_key_descriptor,
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 310) ci->ci_mode->keysize, &payload);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 311) }
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 312) if (IS_ERR(key))
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 313) return PTR_ERR(key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 314)
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 315) err = fscrypt_setup_v1_file_key(ci, payload->raw);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 316) up_read(&key->sem);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 317) key_put(key);
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 318) return err;
0109ce76dd6e9 (Eric Biggers 2019-08-04 19:35:45 -0700 319) }
VisionFive2 Linux kernel
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