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Diffstat (limited to 'daemon/tls.h')
| -rw-r--r-- | daemon/tls.h | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/daemon/tls.h b/daemon/tls.h new file mode 100644 index 0000000..8417bf0 --- /dev/null +++ b/daemon/tls.h @@ -0,0 +1,230 @@ +/* Copyright (C) 2016 American Civil Liberties Union (ACLU) + * SPDX-License-Identifier: GPL-3.0-or-later +*/ + +#pragma once + +#include <uv.h> +#include <gnutls/gnutls.h> +#include <libknot/packet/pkt.h> +#include "lib/defines.h" +#include "lib/generic/array.h" +#include "lib/generic/trie.h" +#include "lib/utils.h" + +#define MAX_TLS_PADDING KR_EDNS_PAYLOAD +#define TLS_MAX_UNCORK_RETRIES 100 + +/* rfc 5476, 7.3 - handshake Protocol overview + * https://tools.ietf.org/html/rfc5246#page-33 + * Message flow for a full handshake (only mandatory messages) + * ClientHello --------> + ServerHello + <-------- ServerHelloDone + ClientKeyExchange + Finished --------> + <-------- Finished + * + * See also https://blog.cloudflare.com/keyless-ssl-the-nitty-gritty-technical-details/ + * So it takes 2 RTT. + * As we use session tickets, there are additional messages, add one RTT mode. + */ + #define TLS_MAX_HANDSHAKE_TIME (KR_CONN_RTT_MAX * 3) + +/** Transport session (opaque). */ +struct session; + +struct tls_ctx; +struct tls_client_ctx; +struct tls_credentials { + int count; + char *tls_cert; + char *tls_key; + gnutls_certificate_credentials_t credentials; + time_t valid_until; + char *ephemeral_servicename; +}; + + +#define TLS_SHA256_RAW_LEN 32 /* gnutls_hash_get_len(GNUTLS_DIG_SHA256) */ +/** Required buffer length for pin_sha256, including the zero terminator. */ +#define TLS_SHA256_BASE64_BUFLEN (((TLS_SHA256_RAW_LEN * 8 + 4) / 6) + 3 + 1) + +#if GNUTLS_VERSION_NUMBER >= 0x030400 + #define TLS_CAN_USE_PINS 1 +#else + #define TLS_CAN_USE_PINS 0 +#endif + + +/** TLS authentication parameters for a single address-port pair. */ +typedef struct { + uint32_t refs; /**< Reference count; consider TLS sessions in progress. */ + bool insecure; /**< Use no authentication. */ + const char *hostname; /**< Server name for SNI and certificate check, lowercased. */ + array_t(const char *) ca_files; /**< Paths to certificate files; not really used. */ + array_t(const uint8_t *) pins; /**< Certificate pins as raw unterminated strings.*/ + gnutls_certificate_credentials_t credentials; /**< CA creds. in gnutls format. */ + gnutls_datum_t session_data; /**< Session-resumption data gets stored here. */ +} tls_client_param_t; +/** Holds configuration for TLS authentication for all potential servers. + * Special case: NULL pointer also means empty. */ +typedef trie_t tls_client_params_t; + +/** Get a pointer-to-pointer to TLS auth params. + * If it didn't exist, it returns NULL (if !do_insert) or pointer to NULL. */ +tls_client_param_t ** tls_client_param_getptr(tls_client_params_t **params, + const struct sockaddr *addr, bool do_insert); + +/** Get a pointer to TLS auth params or NULL. */ +static inline tls_client_param_t * + tls_client_param_get(tls_client_params_t *params, const struct sockaddr *addr) +{ + tls_client_param_t **pe = tls_client_param_getptr(¶ms, addr, false); + return pe ? *pe : NULL; +} + +/** Allocate and initialize the structure (with ->ref = 1). */ +tls_client_param_t * tls_client_param_new(); +/** Reference-counted free(); any inside data is freed alongside. */ +void tls_client_param_unref(tls_client_param_t *entry); + +int tls_client_param_remove(tls_client_params_t *params, const struct sockaddr *addr); +/** Free TLS authentication parameters. */ +void tls_client_params_free(tls_client_params_t *params); + + +struct worker_ctx; +struct qr_task; +struct network; +struct engine; + +typedef enum tls_client_hs_state { + TLS_HS_NOT_STARTED = 0, + TLS_HS_IN_PROGRESS, + TLS_HS_DONE, + TLS_HS_CLOSING, + TLS_HS_LAST +} tls_hs_state_t; + +typedef int (*tls_handshake_cb) (struct session *session, int status); + + +struct tls_common_ctx { + bool client_side; + gnutls_session_t tls_session; + tls_hs_state_t handshake_state; + struct session *session; + /* for reading from the network */ + const uint8_t *buf; + ssize_t nread; + ssize_t consumed; + uint8_t recv_buf[16384]; + tls_handshake_cb handshake_cb; + struct worker_ctx *worker; + size_t write_queue_size; +}; + +struct tls_ctx { + /* + * Since pointer to tls_ctx needs to be casted + * to tls_ctx_common in some functions, + * this field must be always at first position + */ + struct tls_common_ctx c; + struct tls_credentials *credentials; +}; + +struct tls_client_ctx { + /* + * Since pointer to tls_client_ctx needs to be casted + * to tls_ctx_common in some functions, + * this field must be always at first position + */ + struct tls_common_ctx c; + tls_client_param_t *params; /**< It's reference-counted. */ +}; + +/*! Create an empty TLS context in query context */ +struct tls_ctx* tls_new(struct worker_ctx *worker); + +/*! Close a TLS context (call gnutls_bye()) */ +void tls_close(struct tls_common_ctx *ctx); + +/*! Release a TLS context */ +void tls_free(struct tls_ctx* tls); + +/*! Push new data to TLS context for sending */ +int tls_write(uv_write_t *req, uv_handle_t* handle, knot_pkt_t * pkt, uv_write_cb cb); + +/*! Unwrap incoming data from a TLS stream and pass them to TCP session. + * @return the number of newly-completed requests (>=0) or an error code + */ +ssize_t tls_process_input_data(struct session *s, const uint8_t *buf, ssize_t nread); + +/*! Set TLS certificate and key from files. */ +int tls_certificate_set(struct network *net, const char *tls_cert, const char *tls_key); + +/*! Borrow TLS credentials for context. */ +struct tls_credentials *tls_credentials_reserve(struct tls_credentials *tls_credentials); + +/*! Release TLS credentials for context (decrements refcount or frees). */ +int tls_credentials_release(struct tls_credentials *tls_credentials); + +/*! Free TLS credentials, must not be called if it holds positive refcount. */ +void tls_credentials_free(struct tls_credentials *tls_credentials); + +/*! Log DNS-over-TLS OOB key-pin form of current credentials: + * https://tools.ietf.org/html/rfc7858#appendix-A */ +void tls_credentials_log_pins(struct tls_credentials *tls_credentials); + +/*! Generate new ephemeral TLS credentials. */ +struct tls_credentials * tls_get_ephemeral_credentials(struct engine *engine); + +/*! Get TLS handshake state. */ +tls_hs_state_t tls_get_hs_state(const struct tls_common_ctx *ctx); + +/*! Set TLS handshake state. */ +int tls_set_hs_state(struct tls_common_ctx *ctx, tls_hs_state_t state); + + +/*! Allocate new client TLS context */ +struct tls_client_ctx *tls_client_ctx_new(tls_client_param_t *entry, + struct worker_ctx *worker); + +/*! Free client TLS context */ +void tls_client_ctx_free(struct tls_client_ctx *ctx); + +int tls_client_connect_start(struct tls_client_ctx *client_ctx, + struct session *session, + tls_handshake_cb handshake_cb); + +int tls_client_ctx_set_session(struct tls_client_ctx *ctx, struct session *session); + + +/* Session tickets, server side. Implementation in ./tls_session_ticket-srv.c */ + +/*! Opaque struct used by tls_session_ticket_* functions. */ +struct tls_session_ticket_ctx; + +/*! Suggested maximum reasonable secret length. */ +#define TLS_SESSION_TICKET_SECRET_MAX_LEN 1024 + +/*! Create a session ticket context and initialize it (secret gets copied inside). + * + * Passing zero-length secret implies using a random key, i.e. not synchronized + * between multiple instances. + * + * Beware that knowledge of the secret (if nonempty) breaks forward secrecy, + * so you should rotate the secret regularly and securely erase all past secrets. + * With TLS < 1.3 it's probably too risky to set nonempty secret. + */ +struct tls_session_ticket_ctx * tls_session_ticket_ctx_create( + uv_loop_t *loop, const char *secret, size_t secret_len); + +/*! Try to enable session tickets for a server session. */ +void tls_session_ticket_enable(struct tls_session_ticket_ctx *ctx, gnutls_session_t session); + +/*! Free all resources of the session ticket context. NULL is accepted as well. */ +void tls_session_ticket_ctx_destroy(struct tls_session_ticket_ctx *ctx); + |