static int validate_user_key(struct fscrypt_info *crypt_info, struct fscrypt_context *ctx, u8 *raw_key, u8 *prefix, int prefix_size) { u8 *full_key_descriptor; struct key *keyring_key; struct fscrypt_key *master_key; const struct user_key_payload *ukp; int full_key_len = prefix_size + (FS_KEY_DESCRIPTOR_SIZE * 2) + 1; int res; full_key_descriptor = kmalloc(full_key_len, GFP_NOFS); if (!full_key_descriptor) return -ENOMEM; memcpy(full_key_descriptor, prefix, prefix_size); sprintf(full_key_descriptor + prefix_size, "%*phN", FS_KEY_DESCRIPTOR_SIZE, ctx->master_key_descriptor); full_key_descriptor[full_key_len - 1] = '\0'; keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL); kfree(full_key_descriptor); if (IS_ERR(keyring_key)) return PTR_ERR(keyring_key); if (keyring_key->type != &key_type_logon) { printk_once(KERN_WARNING "%s: key type must be logon\n", __func__); res = -ENOKEY; goto out; } down_read(&keyring_key->sem); ukp = user_key_payload(keyring_key); if (ukp->datalen != sizeof(struct fscrypt_key)) { res = -EINVAL; up_read(&keyring_key->sem); goto out; } master_key = (struct fscrypt_key *)ukp->data; BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); if (master_key->size != FS_AES_256_XTS_KEY_SIZE) { printk_once(KERN_WARNING "%s: key size incorrect: %d\n", __func__, master_key->size); res = -ENOKEY; up_read(&keyring_key->sem); goto out; } res = derive_key_aes(ctx->nonce, master_key->raw, raw_key); up_read(&keyring_key->sem); if (res) goto out; crypt_info->ci_keyring_key = keyring_key; return 0; out: key_put(keyring_key); return res; }
static int validate_user_key(struct fscrypt_info *crypt_info, struct fscrypt_context *ctx, u8 *raw_key, const char *prefix, int min_keysize) { char *description; struct key *keyring_key; struct fscrypt_key *master_key; const struct user_key_payload *ukp; int res; description = kasprintf(GFP_NOFS, "%s%*phN", prefix, FS_KEY_DESCRIPTOR_SIZE, ctx->master_key_descriptor); if (!description) return -ENOMEM; keyring_key = request_key(&key_type_logon, description, NULL); kfree(description); if (IS_ERR(keyring_key)) return PTR_ERR(keyring_key); down_read(&keyring_key->sem); if (keyring_key->type != &key_type_logon) { printk_once(KERN_WARNING "%s: key type must be logon\n", __func__); res = -ENOKEY; goto out; } ukp = user_key_payload_locked(keyring_key); if (!ukp) { /* key was revoked before we acquired its semaphore */ res = -EKEYREVOKED; goto out; } if (ukp->datalen != sizeof(struct fscrypt_key)) { res = -EINVAL; goto out; } master_key = (struct fscrypt_key *)ukp->data; BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); if (master_key->size < min_keysize || master_key->size > FS_MAX_KEY_SIZE || master_key->size % AES_BLOCK_SIZE != 0) { printk_once(KERN_WARNING "%s: key size incorrect: %d\n", __func__, master_key->size); res = -ENOKEY; goto out; } res = derive_key_aes(ctx->nonce, master_key, raw_key); out: up_read(&keyring_key->sem); key_put(keyring_key); return res; }
int get_crypt_info(struct inode *inode) { struct fscrypt_info *crypt_info; u8 full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE + (FS_KEY_DESCRIPTOR_SIZE * 2) + 1]; struct key *keyring_key = NULL; struct fscrypt_key *master_key; struct fscrypt_context ctx; struct user_key_payload *ukp; struct crypto_ablkcipher *ctfm; const char *cipher_str; u8 raw_key[FS_MAX_KEY_SIZE]; u8 mode; int res; res = fscrypt_initialize(); if (res) return res; if (!inode->i_sb->s_cop->get_context) return -EOPNOTSUPP; retry: crypt_info = ACCESS_ONCE(inode->i_crypt_info); if (crypt_info) { if (!crypt_info->ci_keyring_key || key_validate(crypt_info->ci_keyring_key) == 0) return 0; fscrypt_put_encryption_info(inode, crypt_info); goto retry; } res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); if (res < 0) { if (!fscrypt_dummy_context_enabled(inode)) return res; ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS; ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS; ctx.flags = 0; } else if (res != sizeof(ctx)) { return -EINVAL; } res = 0; crypt_info = kmem_cache_alloc(fscrypt_info_cachep, GFP_NOFS); if (!crypt_info) return -ENOMEM; crypt_info->ci_flags = ctx.flags; crypt_info->ci_data_mode = ctx.contents_encryption_mode; crypt_info->ci_filename_mode = ctx.filenames_encryption_mode; crypt_info->ci_ctfm = NULL; crypt_info->ci_keyring_key = NULL; memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor, sizeof(crypt_info->ci_master_key)); if (S_ISREG(inode->i_mode)) mode = crypt_info->ci_data_mode; else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) mode = crypt_info->ci_filename_mode; else BUG(); switch (mode) { case FS_ENCRYPTION_MODE_AES_256_XTS: cipher_str = "xts(aes)"; break; case FS_ENCRYPTION_MODE_AES_256_CTS: cipher_str = "cts(cbc(aes))"; break; default: printk_once(KERN_WARNING "%s: unsupported key mode %d (ino %u)\n", __func__, mode, (unsigned) inode->i_ino); res = -ENOKEY; goto out; } if (fscrypt_dummy_context_enabled(inode)) { memset(raw_key, 0x42, FS_AES_256_XTS_KEY_SIZE); goto got_key; } memcpy(full_key_descriptor, FS_KEY_DESC_PREFIX, FS_KEY_DESC_PREFIX_SIZE); sprintf(full_key_descriptor + FS_KEY_DESC_PREFIX_SIZE, "%*phN", FS_KEY_DESCRIPTOR_SIZE, ctx.master_key_descriptor); full_key_descriptor[FS_KEY_DESC_PREFIX_SIZE + (2 * FS_KEY_DESCRIPTOR_SIZE)] = '\0'; keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL); if (IS_ERR(keyring_key)) { res = PTR_ERR(keyring_key); keyring_key = NULL; goto out; } crypt_info->ci_keyring_key = keyring_key; if (keyring_key->type != &key_type_logon) { printk_once(KERN_WARNING "%s: key type must be logon\n", __func__); res = -ENOKEY; goto out; } down_read(&keyring_key->sem); ukp = ((struct user_key_payload *)keyring_key->payload.data); if (ukp->datalen != sizeof(struct fscrypt_key)) { res = -EINVAL; up_read(&keyring_key->sem); goto out; } master_key = (struct fscrypt_key *)ukp->data; BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); if (master_key->size != FS_AES_256_XTS_KEY_SIZE) { printk_once(KERN_WARNING "%s: key size incorrect: %d\n", __func__, master_key->size); res = -ENOKEY; up_read(&keyring_key->sem); goto out; } res = derive_key_aes(ctx.nonce, master_key->raw, raw_key); up_read(&keyring_key->sem); if (res) goto out; got_key: ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0); if (!ctfm || IS_ERR(ctfm)) { res = ctfm ? PTR_ERR(ctfm) : -ENOMEM; printk(KERN_DEBUG "%s: error %d (inode %u) allocating crypto tfm\n", __func__, res, (unsigned) inode->i_ino); goto out; } crypt_info->ci_ctfm = ctfm; crypto_ablkcipher_clear_flags(ctfm, ~0); crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm), CRYPTO_TFM_REQ_WEAK_KEY); res = crypto_ablkcipher_setkey(ctfm, raw_key, fscrypt_key_size(mode)); if (res) goto out; memzero_explicit(raw_key, sizeof(raw_key)); if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) != NULL) { put_crypt_info(crypt_info); goto retry; } return 0; out: if (res == -ENOKEY) res = 0; put_crypt_info(crypt_info); memzero_explicit(raw_key, sizeof(raw_key)); return res; }