tor/src/feature/hs/hs_descriptor.h

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2019-01-16 18:33:22 +01:00
/* Copyright (c) 2016-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file hs_descriptor.h
* \brief Header file for hs_descriptor.c
**/
#ifndef TOR_HS_DESCRIPTOR_H
#define TOR_HS_DESCRIPTOR_H
#include <stdint.h>
#include "core/or/or.h"
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#include "trunnel/ed25519_cert.h" /* needed for trunnel */
#include "feature/nodelist/torcert.h"
/* Trunnel */
struct link_specifier_t;
/** The earliest descriptor format version we support. */
#define HS_DESC_SUPPORTED_FORMAT_VERSION_MIN 3
/** The latest descriptor format version we support. */
#define HS_DESC_SUPPORTED_FORMAT_VERSION_MAX 3
/** Default lifetime of a descriptor in seconds. The valus is set at 3 hours
* which is 180 minutes or 10800 seconds. */
#define HS_DESC_DEFAULT_LIFETIME (3 * 60 * 60)
/** Maximum lifetime of a descriptor in seconds. The value is set at 12 hours
* which is 720 minutes or 43200 seconds. */
#define HS_DESC_MAX_LIFETIME (12 * 60 * 60)
/** Lifetime of certificate in the descriptor. This defines the lifetime of the
* descriptor signing key and the cross certification cert of that key. It is
* set to 54 hours because a descriptor can be around for 48 hours and because
* consensuses are used after the hour, add an extra 6 hours to give some time
* for the service to stop using it. */
#define HS_DESC_CERT_LIFETIME (54 * 60 * 60)
/** Length of the salt needed for the encrypted section of a descriptor. */
#define HS_DESC_ENCRYPTED_SALT_LEN 16
/** Length of the KDF output value which is the length of the secret key,
* the secret IV and MAC key length which is the length of H() output. */
#define HS_DESC_ENCRYPTED_KDF_OUTPUT_LEN \
CIPHER256_KEY_LEN + CIPHER_IV_LEN + DIGEST256_LEN
/** Pad plaintext of superencrypted data section before encryption so that its
* length is a multiple of this value. */
#define HS_DESC_SUPERENC_PLAINTEXT_PAD_MULTIPLE 10000
/** Maximum length in bytes of a full hidden service descriptor. */
#define HS_DESC_MAX_LEN 50000 /* 50kb max size */
/** Key length for the descriptor symmetric encryption. As specified in the
* protocol, we use AES-256 for the encrypted section of the descriptor. The
* following is the length in bytes and the bit size. */
#define HS_DESC_ENCRYPTED_KEY_LEN CIPHER256_KEY_LEN
#define HS_DESC_ENCRYPTED_BIT_SIZE (HS_DESC_ENCRYPTED_KEY_LEN * 8)
/** Length of each components in the auth client section in the descriptor. */
#define HS_DESC_CLIENT_ID_LEN 8
#define HS_DESC_DESCRIPTOR_COOKIE_LEN 16
#define HS_DESC_COOKIE_KEY_LEN 32
#define HS_DESC_COOKIE_KEY_BIT_SIZE (HS_DESC_COOKIE_KEY_LEN * 8)
#define HS_DESC_ENCRYPED_COOKIE_LEN HS_DESC_DESCRIPTOR_COOKIE_LEN
/** The number of auth client entries in the descriptor must be the multiple
* of this constant. */
#define HS_DESC_AUTH_CLIENT_MULTIPLE 16
/** Type of authentication in the descriptor. */
typedef enum {
HS_DESC_AUTH_ED25519 = 1
} hs_desc_auth_type_t;
/** Error code when decoding a descriptor. */
typedef enum {
/* The configured client authorization for the requested .onion address
* failed to decode the descriptor. */
HS_DESC_DECODE_BAD_CLIENT_AUTH = -6,
/* The requested .onion address requires a client authorization. */
HS_DESC_DECODE_NEED_CLIENT_AUTH = -5,
/* Error during decryption of the encrypted layer. */
HS_DESC_DECODE_ENCRYPTED_ERROR = -4,
/* Error during decryption of the super encrypted layer. */
HS_DESC_DECODE_SUPERENC_ERROR = -3,
/* Error while decoding the plaintext section. */
HS_DESC_DECODE_PLAINTEXT_ERROR = -2,
/* Generic error. */
HS_DESC_DECODE_GENERIC_ERROR = -1,
/* Decoding a descriptor was successful. */
HS_DESC_DECODE_OK = 0,
} hs_desc_decode_status_t;
/** Introduction point information located in a descriptor. */
typedef struct hs_desc_intro_point_t {
/** Link specifier(s) which details how to extend to the relay. This list
* contains link_specifier_t objects. It MUST have at least one. */
smartlist_t *link_specifiers;
/** Onion key of the introduction point used to extend to it for the ntor
* handshake. */
curve25519_public_key_t onion_key;
/** Authentication key used to establish the introduction point circuit and
* cross-certifies the blinded public key for the replica thus signed by
* the blinded key and in turn signs it. */
tor_cert_t *auth_key_cert;
/** Encryption key for the "ntor" type. */
curve25519_public_key_t enc_key;
/** Certificate cross certifying the descriptor signing key by the encryption
* curve25519 key. This certificate contains the signing key and is of type
* CERT_TYPE_CROSS_HS_IP_KEYS [0B]. */
tor_cert_t *enc_key_cert;
/** (Optional): If this introduction point is a legacy one that is version <=
* 0.2.9.x (HSIntro=3), we use this extra key for the intro point to be able
* to relay the cells to the service correctly. */
struct {
/** RSA public key. */
crypto_pk_t *key;
/** Cross certified cert with the descriptor signing key (RSA->Ed). Because
* of the cross certification API, we need to keep the certificate binary
* blob and its length in order to properly encode it after. */
struct {
uint8_t *encoded;
size_t len;
} cert;
} legacy;
/** True iff the introduction point has passed the cross certification. Upon
* decoding an intro point, this must be true. */
unsigned int cross_certified : 1;
} hs_desc_intro_point_t;
/** Authorized client information located in a descriptor. */
typedef struct hs_desc_authorized_client_t {
/** An identifier that the client will use to identify which auth client
* entry it needs to use. */
uint8_t client_id[HS_DESC_CLIENT_ID_LEN];
/** An IV that is used to decrypt the encrypted descriptor cookie. */
uint8_t iv[CIPHER_IV_LEN];
/** An encrypted descriptor cookie that the client needs to decrypt to use
* it to decrypt the descriptor. */
uint8_t encrypted_cookie[HS_DESC_ENCRYPED_COOKIE_LEN];
} hs_desc_authorized_client_t;
/** The encrypted data section of a descriptor. Obviously the data in this is
* in plaintext but encrypted once encoded. */
typedef struct hs_desc_encrypted_data_t {
/** Bitfield of CREATE2 cell supported formats. The only currently supported
* format is ntor. */
unsigned int create2_ntor : 1;
/** A list of authentication types that a client must at least support one
* in order to contact the service. Contains NULL terminated strings. */
smartlist_t *intro_auth_types;
/** Is this descriptor a single onion service? */
unsigned int single_onion_service : 1;
/** A list of intro points. Contains hs_desc_intro_point_t objects. */
smartlist_t *intro_points;
} hs_desc_encrypted_data_t;
/** The superencrypted data section of a descriptor. Obviously the data in
* this is in plaintext but encrypted once encoded. */
typedef struct hs_desc_superencrypted_data_t {
/** This field contains ephemeral x25519 public key which is used by
* the encryption scheme in the client authorization. */
curve25519_public_key_t auth_ephemeral_pubkey;
/** A list of authorized clients. Contains hs_desc_authorized_client_t
* objects. */
smartlist_t *clients;
/** Decoding only: The b64-decoded encrypted blob from the descriptor */
uint8_t *encrypted_blob;
/** Decoding only: Size of the encrypted_blob */
size_t encrypted_blob_size;
} hs_desc_superencrypted_data_t;
/** Plaintext data that is unencrypted information of the descriptor. */
typedef struct hs_desc_plaintext_data_t {
/** Version of the descriptor format. Spec specifies this field as a
* positive integer. */
uint32_t version;
/** The lifetime of the descriptor in seconds. */
uint32_t lifetime_sec;
/** Certificate with the short-term ed22519 descriptor signing key for the
* replica which is signed by the blinded public key for that replica. */
tor_cert_t *signing_key_cert;
/** Signing public key which is used to sign the descriptor. Same public key
* as in the signing key certificate. */
ed25519_public_key_t signing_pubkey;
/** Blinded public key used for this descriptor derived from the master
* identity key and generated for a specific replica number. */
ed25519_public_key_t blinded_pubkey;
/** Revision counter is incremented at each upload, regardless of whether
* the descriptor has changed. This avoids leaking whether the descriptor
* has changed. Spec specifies this as a 8 bytes positive integer. */
uint64_t revision_counter;
/** Decoding only: The b64-decoded superencrypted blob from the descriptor */
uint8_t *superencrypted_blob;
/** Decoding only: Size of the superencrypted_blob */
size_t superencrypted_blob_size;
} hs_desc_plaintext_data_t;
/** Service descriptor in its decoded form. */
typedef struct hs_descriptor_t {
/** Contains the plaintext part of the descriptor. */
hs_desc_plaintext_data_t plaintext_data;
/** The following contains what's in the superencrypted part of the
* descriptor. It's only encrypted in the encoded version of the descriptor
* thus the data contained in that object is in plaintext. */
hs_desc_superencrypted_data_t superencrypted_data;
/** The following contains what's in the encrypted part of the descriptor.
* It's only encrypted in the encoded version of the descriptor thus the
* data contained in that object is in plaintext. */
hs_desc_encrypted_data_t encrypted_data;
/** Subcredentials of a service, used by the client and service to decrypt
* the encrypted data. */
uint8_t subcredential[DIGEST256_LEN];
} hs_descriptor_t;
/** Return true iff the given descriptor format version is supported. */
static inline int
hs_desc_is_supported_version(uint32_t version)
{
if (version < HS_DESC_SUPPORTED_FORMAT_VERSION_MIN ||
version > HS_DESC_SUPPORTED_FORMAT_VERSION_MAX) {
return 0;
}
return 1;
}
/* Public API. */
void hs_descriptor_free_(hs_descriptor_t *desc);
#define hs_descriptor_free(desc) \
FREE_AND_NULL(hs_descriptor_t, hs_descriptor_free_, (desc))
void hs_desc_plaintext_data_free_(hs_desc_plaintext_data_t *desc);
#define hs_desc_plaintext_data_free(desc) \
FREE_AND_NULL(hs_desc_plaintext_data_t, hs_desc_plaintext_data_free_, (desc))
void hs_desc_superencrypted_data_free_(hs_desc_superencrypted_data_t *desc);
#define hs_desc_superencrypted_data_free(desc) \
FREE_AND_NULL(hs_desc_superencrypted_data_t, \
hs_desc_superencrypted_data_free_, (desc))
void hs_desc_encrypted_data_free_(hs_desc_encrypted_data_t *desc);
#define hs_desc_encrypted_data_free(desc) \
FREE_AND_NULL(hs_desc_encrypted_data_t, hs_desc_encrypted_data_free_, (desc))
void hs_descriptor_clear_intro_points(hs_descriptor_t *desc);
MOCK_DECL(int,
hs_desc_encode_descriptor,(const hs_descriptor_t *desc,
const ed25519_keypair_t *signing_kp,
const uint8_t *descriptor_cookie,
char **encoded_out));
int hs_desc_decode_descriptor(const char *encoded,
const uint8_t *subcredential,
const curve25519_secret_key_t *client_auth_sk,
hs_descriptor_t **desc_out);
int hs_desc_decode_plaintext(const char *encoded,
hs_desc_plaintext_data_t *plaintext);
int hs_desc_decode_superencrypted(const hs_descriptor_t *desc,
hs_desc_superencrypted_data_t *desc_out);
int hs_desc_decode_encrypted(const hs_descriptor_t *desc,
const curve25519_secret_key_t *client_auth_sk,
hs_desc_encrypted_data_t *desc_out);
size_t hs_desc_obj_size(const hs_descriptor_t *data);
size_t hs_desc_plaintext_obj_size(const hs_desc_plaintext_data_t *data);
hs_desc_intro_point_t *hs_desc_intro_point_new(void);
void hs_desc_intro_point_free_(hs_desc_intro_point_t *ip);
#define hs_desc_intro_point_free(ip) \
FREE_AND_NULL(hs_desc_intro_point_t, hs_desc_intro_point_free_, (ip))
void hs_desc_authorized_client_free_(hs_desc_authorized_client_t *client);
#define hs_desc_authorized_client_free(client) \
FREE_AND_NULL(hs_desc_authorized_client_t, \
hs_desc_authorized_client_free_, (client))
hs_desc_authorized_client_t *hs_desc_build_fake_authorized_client(void);
void hs_desc_build_authorized_client(const uint8_t *subcredential,
const curve25519_public_key_t *
client_auth_pk,
const curve25519_secret_key_t *
auth_ephemeral_sk,
const uint8_t *descriptor_cookie,
hs_desc_authorized_client_t *client_out);
void hs_desc_plaintext_data_free_contents(hs_desc_plaintext_data_t *desc);
void hs_desc_superencrypted_data_free_contents(
hs_desc_superencrypted_data_t *desc);
void hs_desc_encrypted_data_free_contents(hs_desc_encrypted_data_t *desc);
#ifdef HS_DESCRIPTOR_PRIVATE
/* Encoding. */
STATIC char *encode_link_specifiers(const smartlist_t *specs);
STATIC size_t build_plaintext_padding(const char *plaintext,
size_t plaintext_len,
uint8_t **padded_out);
/* Decoding. */
STATIC smartlist_t *decode_link_specifiers(const char *encoded);
STATIC hs_desc_intro_point_t *decode_introduction_point(
const hs_descriptor_t *desc,
const char *text);
STATIC int encrypted_data_length_is_valid(size_t len);
STATIC int cert_is_valid(tor_cert_t *cert, uint8_t type,
const char *log_obj_type);
STATIC int desc_sig_is_valid(const char *b64_sig,
const ed25519_public_key_t *signing_pubkey,
const char *encoded_desc, size_t encoded_len);
MOCK_DECL(STATIC size_t, decrypt_desc_layer,(const hs_descriptor_t *desc,
const uint8_t *descriptor_cookie,
bool is_superencrypted_layer,
char **decrypted_out));
#endif /* defined(HS_DESCRIPTOR_PRIVATE) */
#endif /* !defined(TOR_HS_DESCRIPTOR_H) */