286 lines
12 KiB
C
286 lines
12 KiB
C
/* Copyright (c) 2016-2017, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file hs_descriptor.h
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* \brief Header file for hs_descriptor.c
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**/
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#ifndef TOR_HS_DESCRIPTOR_H
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#define TOR_HS_DESCRIPTOR_H
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#include <stdint.h>
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#include "or.h"
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#include "address.h"
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#include "container.h"
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#include "crypto.h"
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#include "crypto_ed25519.h"
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#include "ed25519_cert.h" /* needed for trunnel */
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#include "torcert.h"
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/* Trunnel */
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struct link_specifier_t;
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/* The earliest descriptor format version we support. */
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#define HS_DESC_SUPPORTED_FORMAT_VERSION_MIN 3
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/* The latest descriptor format version we support. */
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#define HS_DESC_SUPPORTED_FORMAT_VERSION_MAX 3
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/* Default lifetime of a descriptor in seconds. The valus is set at 3 hours
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* which is 180 minutes or 10800 seconds. */
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#define HS_DESC_DEFAULT_LIFETIME (3 * 60 * 60)
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/* Maximum lifetime of a descriptor in seconds. The value is set at 12 hours
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* which is 720 minutes or 43200 seconds. */
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#define HS_DESC_MAX_LIFETIME (12 * 60 * 60)
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/* Lifetime of certificate in the descriptor. This defines the lifetime of the
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* descriptor signing key and the cross certification cert of that key. It is
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* set to 54 hours because a descriptor can be around for 48 hours and because
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* consensuses are used after the hour, add an extra 6 hours to give some time
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* for the service to stop using it. */
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#define HS_DESC_CERT_LIFETIME (54 * 60 * 60)
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/* Length of the salt needed for the encrypted section of a descriptor. */
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#define HS_DESC_ENCRYPTED_SALT_LEN 16
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/* Length of the secret input needed for the KDF construction which derives
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* the encryption key for the encrypted data section of the descriptor. This
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* adds up to 68 bytes being the blinded key, hashed subcredential and
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* revision counter. */
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#define HS_DESC_ENCRYPTED_SECRET_INPUT_LEN \
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ED25519_PUBKEY_LEN + DIGEST256_LEN + sizeof(uint64_t)
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/* Length of the KDF output value which is the length of the secret key,
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* the secret IV and MAC key length which is the length of H() output. */
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#define HS_DESC_ENCRYPTED_KDF_OUTPUT_LEN \
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CIPHER256_KEY_LEN + CIPHER_IV_LEN + DIGEST256_LEN
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/* Pad plaintext of superencrypted data section before encryption so that its
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* length is a multiple of this value. */
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#define HS_DESC_SUPERENC_PLAINTEXT_PAD_MULTIPLE 10000
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/* Maximum length in bytes of a full hidden service descriptor. */
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#define HS_DESC_MAX_LEN 50000 /* 50kb max size */
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/* Key length for the descriptor symmetric encryption. As specified in the
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* protocol, we use AES-256 for the encrypted section of the descriptor. The
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* following is the length in bytes and the bit size. */
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#define HS_DESC_ENCRYPTED_KEY_LEN CIPHER256_KEY_LEN
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#define HS_DESC_ENCRYPTED_BIT_SIZE (HS_DESC_ENCRYPTED_KEY_LEN * 8)
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/* Type of authentication in the descriptor. */
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typedef enum {
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HS_DESC_AUTH_ED25519 = 1
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} hs_desc_auth_type_t;
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/* Link specifier object that contains information on how to extend to the
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* relay that is the address, port and handshake type. */
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typedef struct hs_desc_link_specifier_t {
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/* Indicate the type of link specifier. See trunnel ed25519_cert
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* specification. */
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uint8_t type;
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/* It must be one of these types, can't be more than one. */
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union {
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/* IP address and port of the relay use to extend. */
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tor_addr_port_t ap;
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/* Legacy identity. A 20-byte SHA1 identity fingerprint. */
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uint8_t legacy_id[DIGEST_LEN];
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/* ed25519 identity. A 32-byte key. */
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uint8_t ed25519_id[ED25519_PUBKEY_LEN];
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} u;
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} hs_desc_link_specifier_t;
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/* Introduction point information located in a descriptor. */
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typedef struct hs_desc_intro_point_t {
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/* Link specifier(s) which details how to extend to the relay. This list
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* contains hs_desc_link_specifier_t object. It MUST have at least one. */
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smartlist_t *link_specifiers;
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/* Onion key of the introduction point used to extend to it for the ntor
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* handshake. */
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curve25519_public_key_t onion_key;
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/* Authentication key used to establish the introduction point circuit and
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* cross-certifies the blinded public key for the replica thus signed by
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* the blinded key and in turn signs it. */
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tor_cert_t *auth_key_cert;
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/* Encryption key for the "ntor" type. */
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curve25519_public_key_t enc_key;
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/* Certificate cross certifying the descriptor signing key by the encryption
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* curve25519 key. This certificate contains the signing key and is of type
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* CERT_TYPE_CROSS_HS_IP_KEYS [0B]. */
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tor_cert_t *enc_key_cert;
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/* (Optional): If this introduction point is a legacy one that is version <=
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* 0.2.9.x (HSIntro=3), we use this extra key for the intro point to be able
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* to relay the cells to the service correctly. */
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struct {
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/* RSA public key. */
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crypto_pk_t *key;
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/* Cross certified cert with the descriptor signing key (RSA->Ed). Because
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* of the cross certification API, we need to keep the certificate binary
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* blob and its length in order to properly encode it after. */
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struct {
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uint8_t *encoded;
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size_t len;
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} cert;
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} legacy;
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/* True iff the introduction point has passed the cross certification. Upon
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* decoding an intro point, this must be true. */
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unsigned int cross_certified : 1;
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} hs_desc_intro_point_t;
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/* The encrypted data section of a descriptor. Obviously the data in this is
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* in plaintext but encrypted once encoded. */
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typedef struct hs_desc_encrypted_data_t {
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/* Bitfield of CREATE2 cell supported formats. The only currently supported
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* format is ntor. */
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unsigned int create2_ntor : 1;
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/* A list of authentication types that a client must at least support one
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* in order to contact the service. Contains NULL terminated strings. */
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smartlist_t *intro_auth_types;
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/* Is this descriptor a single onion service? */
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unsigned int single_onion_service : 1;
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/* A list of intro points. Contains hs_desc_intro_point_t objects. */
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smartlist_t *intro_points;
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} hs_desc_encrypted_data_t;
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/* Plaintext data that is unencrypted information of the descriptor. */
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typedef struct hs_desc_plaintext_data_t {
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/* Version of the descriptor format. Spec specifies this field as a
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* positive integer. */
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uint32_t version;
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/* The lifetime of the descriptor in seconds. */
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uint32_t lifetime_sec;
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/* Certificate with the short-term ed22519 descriptor signing key for the
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* replica which is signed by the blinded public key for that replica. */
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tor_cert_t *signing_key_cert;
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/* Signing public key which is used to sign the descriptor. Same public key
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* as in the signing key certificate. */
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ed25519_public_key_t signing_pubkey;
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/* Blinded public key used for this descriptor derived from the master
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* identity key and generated for a specific replica number. */
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ed25519_public_key_t blinded_pubkey;
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/* Revision counter is incremented at each upload, regardless of whether
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* the descriptor has changed. This avoids leaking whether the descriptor
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* has changed. Spec specifies this as a 8 bytes positive integer. */
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uint64_t revision_counter;
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/* Decoding only: The b64-decoded superencrypted blob from the descriptor */
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uint8_t *superencrypted_blob;
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/* Decoding only: Size of the superencrypted_blob */
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size_t superencrypted_blob_size;
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} hs_desc_plaintext_data_t;
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/* Service descriptor in its decoded form. */
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typedef struct hs_descriptor_t {
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/* Contains the plaintext part of the descriptor. */
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hs_desc_plaintext_data_t plaintext_data;
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/* The following contains what's in the encrypted part of the descriptor.
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* It's only encrypted in the encoded version of the descriptor thus the
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* data contained in that object is in plaintext. */
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hs_desc_encrypted_data_t encrypted_data;
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/* Subcredentials of a service, used by the client and service to decrypt
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* the encrypted data. */
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uint8_t subcredential[DIGEST256_LEN];
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} hs_descriptor_t;
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/* Return true iff the given descriptor format version is supported. */
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static inline int
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hs_desc_is_supported_version(uint32_t version)
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{
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if (version < HS_DESC_SUPPORTED_FORMAT_VERSION_MIN ||
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version > HS_DESC_SUPPORTED_FORMAT_VERSION_MAX) {
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return 0;
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}
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return 1;
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}
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/* Public API. */
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void hs_descriptor_free_(hs_descriptor_t *desc);
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#define hs_descriptor_free(desc) \
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FREE_AND_NULL(hs_descriptor_t, hs_descriptor_free_, (desc))
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void hs_desc_plaintext_data_free_(hs_desc_plaintext_data_t *desc);
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#define hs_desc_plaintext_data_free(desc) \
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FREE_AND_NULL(hs_desc_plaintext_data_t, hs_desc_plaintext_data_free_, (desc))
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void hs_desc_encrypted_data_free_(hs_desc_encrypted_data_t *desc);
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#define hs_desc_encrypted_data_free(desc) \
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FREE_AND_NULL(hs_desc_encrypted_data_t, hs_desc_encrypted_data_free_, (desc))
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void hs_desc_link_specifier_free_(hs_desc_link_specifier_t *ls);
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#define hs_desc_link_specifier_free(ls) \
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FREE_AND_NULL(hs_desc_link_specifier_t, hs_desc_link_specifier_free_, (ls))
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hs_desc_link_specifier_t *hs_desc_link_specifier_new(
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const extend_info_t *info, uint8_t type);
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void hs_descriptor_clear_intro_points(hs_descriptor_t *desc);
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MOCK_DECL(int,
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hs_desc_encode_descriptor,(const hs_descriptor_t *desc,
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const ed25519_keypair_t *signing_kp,
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char **encoded_out));
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int hs_desc_decode_descriptor(const char *encoded,
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const uint8_t *subcredential,
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hs_descriptor_t **desc_out);
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int hs_desc_decode_plaintext(const char *encoded,
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hs_desc_plaintext_data_t *plaintext);
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int hs_desc_decode_encrypted(const hs_descriptor_t *desc,
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hs_desc_encrypted_data_t *desc_out);
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size_t hs_desc_obj_size(const hs_descriptor_t *data);
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size_t hs_desc_plaintext_obj_size(const hs_desc_plaintext_data_t *data);
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hs_desc_intro_point_t *hs_desc_intro_point_new(void);
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void hs_desc_intro_point_free_(hs_desc_intro_point_t *ip);
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#define hs_desc_intro_point_free(ip) \
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FREE_AND_NULL(hs_desc_intro_point_t, hs_desc_intro_point_free_, (ip))
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link_specifier_t *hs_desc_lspec_to_trunnel(
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const hs_desc_link_specifier_t *spec);
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#ifdef HS_DESCRIPTOR_PRIVATE
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/* Encoding. */
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STATIC char *encode_link_specifiers(const smartlist_t *specs);
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STATIC size_t build_plaintext_padding(const char *plaintext,
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size_t plaintext_len,
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uint8_t **padded_out);
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/* Decoding. */
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STATIC smartlist_t *decode_link_specifiers(const char *encoded);
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STATIC hs_desc_intro_point_t *decode_introduction_point(
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const hs_descriptor_t *desc,
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const char *text);
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STATIC int encrypted_data_length_is_valid(size_t len);
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STATIC int cert_is_valid(tor_cert_t *cert, uint8_t type,
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const char *log_obj_type);
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STATIC int desc_sig_is_valid(const char *b64_sig,
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const ed25519_public_key_t *signing_pubkey,
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const char *encoded_desc, size_t encoded_len);
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STATIC size_t decode_superencrypted(const char *message, size_t message_len,
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uint8_t **encrypted_out);
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STATIC void desc_plaintext_data_free_contents(hs_desc_plaintext_data_t *desc);
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MOCK_DECL(STATIC size_t, decrypt_desc_layer,(const hs_descriptor_t *desc,
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const uint8_t *encrypted_blob,
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size_t encrypted_blob_size,
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int is_superencrypted_layer,
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char **decrypted_out));
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#endif /* defined(HS_DESCRIPTOR_PRIVATE) */
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#endif /* !defined(TOR_HS_DESCRIPTOR_H) */
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