ssl/record/recordmethod.h

   1 /*
   2  * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #ifndef OSSL_INTERNAL_RECORDMETHOD_H
  11 # define OSSL_INTERNAL_RECORDMETHOD_H
  12 # pragma once
  13
  14 # include <openssl/ssl.h>
  15
  16 /*
  17  * We use the term "record" here to refer to a packet of data. Records are
  18  * typically protected via a cipher and MAC, or an AEAD cipher (although not
  19  * always). This usage of the term record is consistent with the TLS concept.
  20  * In QUIC the term "record" is not used but it is analogous to the QUIC term
  21  * "packet". The interface in this file applies to all protocols that protect
  22  * records/packets of data, i.e. (D)TLS and QUIC. The term record is used to
  23  * refer to both contexts.
  24  */
  25
  26 /*
  27  * An OSSL_RECORD_METHOD is a protcol specific method which provides the
  28  * functions for reading and writing records for that protocol. Which
  29  * OSSL_RECORD_METHOD to use for a given protocol is defined by the SSL_METHOD.
  30  */
  31 typedef struct ossl_record_method_st OSSL_RECORD_METHOD;
  32
  33 /*
  34  * An OSSL_RECORD_LAYER is just an externally defined opaque pointer created by
  35  * the method
  36  */
  37 typedef struct ossl_record_layer_st OSSL_RECORD_LAYER;
  38
  39
  40 # define OSSL_RECORD_ROLE_CLIENT 0
  41 # define OSSL_RECORD_ROLE_SERVER 1
  42
  43 # define OSSL_RECORD_DIRECTION_READ  0
  44 # define OSSL_RECORD_DIRECTION_WRITE 1
  45
  46 /*
  47  * Protection level. For <= TLSv1.2 only "NONE" and "APPLICATION" are used.
  48  */
  49 # define OSSL_RECORD_PROTECTION_LEVEL_NONE        0
  50 # define OSSL_RECORD_PROTECTION_LEVEL_EARLY       1
  51 # define OSSL_RECORD_PROTECTION_LEVEL_HANDSHAKE   2
  52 # define OSSL_RECORD_PROTECTION_LEVEL_APPLICATION 3
  53
  54 # define OSSL_RECORD_RETURN_SUCCESS           1
  55 # define OSSL_RECORD_RETURN_RETRY             0
  56 # define OSSL_RECORD_RETURN_NON_FATAL_ERR    -1
  57 # define OSSL_RECORD_RETURN_FATAL            -2
  58 # define OSSL_RECORD_RETURN_EOF              -3
  59
  60 /*
  61  * Template for creating a record. A record consists of the |type| of data it
  62  * will contain (e.g. alert, handshake, application data, etc) along with a
  63  * buffer of payload data in |buf| of length |buflen|.
  64  */
  65 struct ossl_record_template_st {
  66     int type;
  67     unsigned int version;
  68     const unsigned char *buf;
  69     size_t buflen;
  70 };
  71
  72 typedef struct ossl_record_template_st OSSL_RECORD_TEMPLATE;
  73
  74 /*
  75  * Rather than a "method" approach, we could make this fetchable - Should we?
  76  * There could be some complexity in finding suitable record layer implementations
  77  * e.g. we need to find one that matches the negotiated protocol, cipher,
  78  * extensions, etc. The selection_cb approach given above doesn't work so well
  79  * if unknown third party providers with OSSL_RECORD_METHOD implementations are
  80  * loaded.
  81  */
  82
  83 /*
  84  * If this becomes public API then we will need functions to create and
  85  * free an OSSL_RECORD_METHOD, as well as functions to get/set the various
  86  * function pointers....unless we make it fetchable.
  87  */
  88 struct ossl_record_method_st {
  89     /*
  90      * Create a new OSSL_RECORD_LAYER object for handling the protocol version
  91      * set by |vers|. |role| is 0 for client and 1 for server. |direction|
  92      * indicates either read or write. |level| is the protection level as
  93      * described above. |settings| are mandatory settings that will cause the
  94      * new() call to fail if they are not understood (for example to require
  95      * Encrypt-Then-Mac support). |options| are optional settings that will not
  96      * cause the new() call to fail if they are not understood (for example
  97      * whether to use "read ahead" or not).
  98      *
  99      * The BIO in |transport| is the BIO for the underlying transport layer.
 100      * Where the direction is "read", then this BIO will only ever be used for
 101      * reading data. Where the direction is "write", then this BIO will only
 102      * every be used for writing data.
 103      *
 104      * An SSL object will always have at least 2 OSSL_RECORD_LAYER objects in
 105      * force at any one time (one for reading and one for writing). In some
 106      * protocols more than 2 might be used (e.g. in DTLS for retransmitting
 107      * messages from an earlier epoch).
 108      *
 109      * The created OSSL_RECORD_LAYER object is stored in *ret on success (or
 110      * NULL otherwise). The return value will be one of
 111      * OSSL_RECORD_RETURN_SUCCESS, OSSL_RECORD_RETURN_FATAL or
 112      * OSSL_RECORD_RETURN_NON_FATAL. A non-fatal return means that creation of
 113      * the record layer has failed because it is unsuitable, but an alternative
 114      * record layer can be tried instead.
 115      */
 116
 117     /*
 118      * If we eventually make this fetchable then we will need to use something
 119      * other than EVP_CIPHER. Also mactype would not be a NID, but a string. For
 120      * now though, this works.
 121      */
 122     int (*new_record_layer)(OSSL_LIB_CTX *libctx,
 123                             const char *propq, int vers,
 124                             int role, int direction,
 125                             int level,
 126                             uint16_t epoch,
 127                             unsigned char *key,
 128                             size_t keylen,
 129                             unsigned char *iv,
 130                             size_t ivlen,
 131                             unsigned char *mackey,
 132                             size_t mackeylen,
 133                             const EVP_CIPHER *ciph,
 134                             size_t taglen,
 135                             int mactype,
 136                             const EVP_MD *md,
 137                             const SSL_COMP *comp,
 138                             BIO *prev,
 139                             BIO *transport,
 140                             BIO *next,
 141                             BIO_ADDR *local,
 142                             BIO_ADDR *peer,
 143                             const OSSL_PARAM *settings,
 144                             const OSSL_PARAM *options,
 145                             const OSSL_DISPATCH *fns,
 146                             void *cbarg,
 147                             OSSL_RECORD_LAYER **ret);
 148     int (*free)(OSSL_RECORD_LAYER *rl);
 149
 150     int (*reset)(OSSL_RECORD_LAYER *rl); /* Is this needed? */
 151
 152     /* Returns 1 if we have unprocessed data buffered or 0 otherwise */
 153     int (*unprocessed_read_pending)(OSSL_RECORD_LAYER *rl);
 154
 155     /*
 156      * Returns 1 if we have processed data buffered that can be read or 0 otherwise
 157      * - not necessarily app data
 158      */
 159     int (*processed_read_pending)(OSSL_RECORD_LAYER *rl);
 160
 161     /*
 162      * The amount of processed app data that is internally bufferred and
 163      * available to read
 164      */
 165     size_t (*app_data_pending)(OSSL_RECORD_LAYER *rl);
 166
 167     int (*write_pending)(OSSL_RECORD_LAYER *rl);
 168
 169     /*
 170      * Find out the maximum amount of plaintext data that the record layer is
 171      * prepared to write in a single record. When calling write_records it is
 172      * the caller's responsibility to ensure that no record template exceeds
 173      * this maximum when calling write_records.
 174      */
 175     size_t (*get_max_record_len)(OSSL_RECORD_LAYER *rl);
 176
 177     /*
 178      * Find out the maximum number of records that the record layer is prepared
 179      * to process in a single call to write_records. It is the caller's
 180      * responsibility to ensure that no call to write_records exceeds this
 181      * number of records. |type| is the type of the records that the caller
 182      * wants to write, and |buflen| is the total amount of data that it wants
 183      * to send. |maxfrag| is the maximum allowed fragment size based on user
 184      * configuration, or TLS parameter negotiation. |*preffrag| contains on
 185      * entry the default fragment size that will actually be used based on user
 186      * configuration. This will always be less than or equal to |maxfrag|. On
 187      * exit the record layer may update this to an alternative fragment size to
 188      * be used. This must always be less than or equal to |maxfrag|.
 189      */
 190     size_t (*get_max_records)(OSSL_RECORD_LAYER *rl, int type, size_t buflen,
 191                               size_t maxfrag, size_t *preffrag);
 192
 193     /*
 194      * Write |numtempl| records from the array of record templates pointed to
 195      * by |templates|. Each record should be no longer than the value returned
 196      * by get_max_record_len(), and there should be no more records than the
 197      * value returned by get_max_records().
 198      * Where possible the caller will attempt to ensure that all records are the
 199      * same length, except the last record. This may not always be possible so
 200      * the record method implementation should not rely on this being the case.
 201      * In the event of a retry the caller should call retry_write_records()
 202      * to try again. No more calls to write_records() should be attempted until
 203      * retry_write_records() returns success.
 204      * Buffers allocated for the record templates can be freed immediately after
 205      * write_records() returns - even in the case a retry.
 206      * The record templates represent the plaintext payload. The encrypted
 207      * output is written to the |transport| BIO.
 208      * Returns:
 209      *  1 on success
 210      *  0 on retry
 211      * -1 on failure
 212      */
 213     int (*write_records)(OSSL_RECORD_LAYER *rl, OSSL_RECORD_TEMPLATE *templates,
 214                          size_t numtempl);
 215
 216     /*
 217      * Retry a previous call to write_records. The caller should continue to
 218      * call this until the function returns with success or failure. After
 219      * each retry more of the data may have been incrementally sent.
 220      * Returns:
 221      *  1 on success
 222      *  0 on retry
 223      * -1 on failure
 224      */
 225     int (*retry_write_records)(OSSL_RECORD_LAYER *rl);
 226
 227     /*
 228      * Read a record and return the record layer version and record type in
 229      * the |rversion| and |type| parameters. |*data| is set to point to a
 230      * record layer buffer containing the record payload data and |*datalen|
 231      * is filled in with the length of that data. The |epoch| and |seq_num|
 232      * values are only used if DTLS has been negotiated. In that case they are
 233      * filled in with the epoch and sequence number from the record.
 234      * An opaque record layer handle for the record is returned in |*rechandle|
 235      * which is used in a subsequent call to |release_record|. The buffer must
 236      * remain available until release_record is called.
 237      *
 238      * Internally the the OSSL_RECORD_METHOD the implementation may read/process
 239      * multiple records in one go and buffer them.
 240      */
 241     int (*read_record)(OSSL_RECORD_LAYER *rl, void **rechandle, int *rversion,
 242                       int *type, unsigned char **data, size_t *datalen,
 243                       uint16_t *epoch, unsigned char *seq_num);
 244     /*
 245      * Release a buffer associated with a record previously read with
 246      * read_record. Records are guaranteed to be released in the order that they
 247      * are read.
 248      */
 249     int (*release_record)(OSSL_RECORD_LAYER *rl, void *rechandle);
 250
 251     /*
 252      * In the event that a fatal error is returned from the functions above then
 253      * get_alert_code() can be called to obtain a more details identifier for
 254      * the error. In (D)TLS this is the alert description code.
 255      */
 256     int (*get_alert_code)(OSSL_RECORD_LAYER *rl);
 257
 258     /*
 259      * Update the transport BIO from the one originally set in the
 260      * new_record_layer call
 261      */
 262     int (*set1_bio)(OSSL_RECORD_LAYER *rl, BIO *bio);
 263
 264     /* Called when protocol negotiation selects a protocol version to use */
 265     int (*set_protocol_version)(OSSL_RECORD_LAYER *rl, int version);
 266
 267     /*
 268      * Whether we are allowed to receive unencrypted alerts, even if we might
 269      * otherwise expect encrypted records. Ignored by protocol versions where
 270      * this isn't relevant
 271      */
 272     void (*set_plain_alerts)(OSSL_RECORD_LAYER *rl, int allow);
 273
 274     /*
 275      * Called immediately after creation of the record layer if we are in a
 276      * first handshake. Also called at the end of the first handshake
 277      */
 278     void (*set_first_handshake)(OSSL_RECORD_LAYER *rl, int first);
 279
 280     /*
 281      * Set the maximum number of pipelines that the record layer should process.
 282      * The default is 1.
 283      */
 284     void (*set_max_pipelines)(OSSL_RECORD_LAYER *rl, size_t max_pipelines);
 285
 286     /*
 287      * Called to tell the record layer whether we are currently "in init" or
 288      * not. Default at creation of the record layer is "yes".
 289      */
 290     void (*set_in_init)(OSSL_RECORD_LAYER *rl, int in_init);
 291
 292     /*
 293      * Get a short or long human readable description of the record layer state
 294      */
 295     void (*get_state)(OSSL_RECORD_LAYER *rl, const char **shortstr,
 296                       const char **longstr);
 297
 298     /*
 299      * Set new options or modify ones that were originaly specified in the
 300      * new_record_layer call.
 301      */
 302     int (*set_options)(OSSL_RECORD_LAYER *rl, const OSSL_PARAM *options);
 303 };
 304
 305
 306 /* Standard built-in record methods */
 307 extern const OSSL_RECORD_METHOD ossl_tls_record_method;
 308 # ifndef OPENSSL_NO_KTLS
 309 extern const OSSL_RECORD_METHOD ossl_ktls_record_method;
 310 # endif
 311 extern const OSSL_RECORD_METHOD ossl_dtls_record_method;
 312
 313 #endif /* !defined(OSSL_INTERNAL_RECORDMETHOD_H) */