1 /* 2 * Copyright 2022-2025 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 protocol 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 #define OSSL_RECORD_ROLE_CLIENT 0 40 #define OSSL_RECORD_ROLE_SERVER 1 41 42 #define OSSL_RECORD_DIRECTION_READ 0 43 #define OSSL_RECORD_DIRECTION_WRITE 1 44 45 #define OSSL_RECORD_RETURN_SUCCESS 1 46 #define OSSL_RECORD_RETURN_RETRY 0 47 #define OSSL_RECORD_RETURN_NON_FATAL_ERR -1 48 #define OSSL_RECORD_RETURN_FATAL -2 49 #define OSSL_RECORD_RETURN_EOF -3 50 51 /* 52 * Template for creating a record. A record consists of the |type| of data it 53 * will contain (e.g. alert, handshake, application data, etc) along with a 54 * buffer of payload data in |buf| of length |buflen|. 55 */ 56 struct ossl_record_template_st { 57 unsigned char type; 58 unsigned int version; 59 const unsigned char *buf; 60 size_t buflen; 61 }; 62 63 typedef struct ossl_record_template_st OSSL_RECORD_TEMPLATE; 64 65 /* 66 * Rather than a "method" approach, we could make this fetchable - Should we? 67 * There could be some complexity in finding suitable record layer implementations 68 * e.g. we need to find one that matches the negotiated protocol, cipher, 69 * extensions, etc. The selection_cb approach given above doesn't work so well 70 * if unknown third party providers with OSSL_RECORD_METHOD implementations are 71 * loaded. 72 */ 73 74 /* 75 * If this becomes public API then we will need functions to create and 76 * free an OSSL_RECORD_METHOD, as well as functions to get/set the various 77 * function pointers....unless we make it fetchable. 78 */ 79 struct ossl_record_method_st { 80 /* 81 * Create a new OSSL_RECORD_LAYER object for handling the protocol version 82 * set by |vers|. |role| is 0 for client and 1 for server. |direction| 83 * indicates either read or write. |level| is the protection level as 84 * described above. |settings| are mandatory settings that will cause the 85 * new() call to fail if they are not understood (for example to require 86 * Encrypt-Then-Mac support). |options| are optional settings that will not 87 * cause the new() call to fail if they are not understood (for example 88 * whether to use "read ahead" or not). 89 * 90 * The BIO in |transport| is the BIO for the underlying transport layer. 91 * Where the direction is "read", then this BIO will only ever be used for 92 * reading data. Where the direction is "write", then this BIO will only 93 * every be used for writing data. 94 * 95 * An SSL object will always have at least 2 OSSL_RECORD_LAYER objects in 96 * force at any one time (one for reading and one for writing). In some 97 * protocols more than 2 might be used (e.g. in DTLS for retransmitting 98 * messages from an earlier epoch). 99 * 100 * The created OSSL_RECORD_LAYER object is stored in *ret on success (or 101 * NULL otherwise). The return value will be one of 102 * OSSL_RECORD_RETURN_SUCCESS, OSSL_RECORD_RETURN_FATAL or 103 * OSSL_RECORD_RETURN_NON_FATAL. A non-fatal return means that creation of 104 * the record layer has failed because it is unsuitable, but an alternative 105 * record layer can be tried instead. 106 */ 107 108 /* 109 * If we eventually make this fetchable then we will need to use something 110 * other than EVP_CIPHER. Also mactype would not be a NID, but a string. For 111 * now though, this works. 112 */ 113 int (*new_record_layer)(OSSL_LIB_CTX *libctx, 114 const char *propq, int vers, 115 int role, int direction, 116 int level, 117 uint16_t epoch, 118 unsigned char *secret, 119 size_t secretlen, 120 unsigned char *key, 121 size_t keylen, 122 unsigned char *iv, 123 size_t ivlen, 124 unsigned char *mackey, 125 size_t mackeylen, 126 const EVP_CIPHER *ciph, 127 size_t taglen, 128 int mactype, 129 const EVP_MD *md, 130 COMP_METHOD *comp, 131 const EVP_MD *kdfdigest, 132 BIO *prev, 133 BIO *transport, 134 BIO *next, 135 BIO_ADDR *local, 136 BIO_ADDR *peer, 137 const OSSL_PARAM *settings, 138 const OSSL_PARAM *options, 139 const OSSL_DISPATCH *fns, 140 void *cbarg, 141 void *rlarg, 142 OSSL_RECORD_LAYER **ret); 143 int (*free)(OSSL_RECORD_LAYER *rl); 144 145 /* Returns 1 if we have unprocessed data buffered or 0 otherwise */ 146 int (*unprocessed_read_pending)(OSSL_RECORD_LAYER *rl); 147 148 /* 149 * Returns 1 if we have processed data buffered that can be read or 0 otherwise 150 * - not necessarily app data 151 */ 152 int (*processed_read_pending)(OSSL_RECORD_LAYER *rl); 153 154 /* 155 * The amount of processed app data that is internally buffered and 156 * available to read 157 */ 158 size_t (*app_data_pending)(OSSL_RECORD_LAYER *rl); 159 160 /* 161 * Find out the maximum number of records that the record layer is prepared 162 * to process in a single call to write_records. It is the caller's 163 * responsibility to ensure that no call to write_records exceeds this 164 * number of records. |type| is the type of the records that the caller 165 * wants to write, and |len| is the total amount of data that it wants 166 * to send. |maxfrag| is the maximum allowed fragment size based on user 167 * configuration, or TLS parameter negotiation. |*preffrag| contains on 168 * entry the default fragment size that will actually be used based on user 169 * configuration. This will always be less than or equal to |maxfrag|. On 170 * exit the record layer may update this to an alternative fragment size to 171 * be used. This must always be less than or equal to |maxfrag|. 172 */ 173 size_t (*get_max_records)(OSSL_RECORD_LAYER *rl, uint8_t type, size_t len, 174 size_t maxfrag, size_t *preffrag); 175 176 /* 177 * Write |numtempl| records from the array of record templates pointed to 178 * by |templates|. Each record should be no longer than the value returned 179 * by get_max_record_len(), and there should be no more records than the 180 * value returned by get_max_records(). 181 * Where possible the caller will attempt to ensure that all records are the 182 * same length, except the last record. This may not always be possible so 183 * the record method implementation should not rely on this being the case. 184 * In the event of a retry the caller should call retry_write_records() 185 * to try again. No more calls to write_records() should be attempted until 186 * retry_write_records() returns success. 187 * Buffers allocated for the record templates can be freed immediately after 188 * write_records() returns - even in the case a retry. 189 * The record templates represent the plaintext payload. The encrypted 190 * output is written to the |transport| BIO. 191 * Returns: 192 * 1 on success 193 * 0 on retry 194 * -1 on failure 195 */ 196 int (*write_records)(OSSL_RECORD_LAYER *rl, OSSL_RECORD_TEMPLATE *templates, 197 size_t numtempl); 198 199 /* 200 * Retry a previous call to write_records. The caller should continue to 201 * call this until the function returns with success or failure. After 202 * each retry more of the data may have been incrementally sent. 203 * Returns: 204 * 1 on success 205 * 0 on retry 206 * -1 on failure 207 */ 208 int (*retry_write_records)(OSSL_RECORD_LAYER *rl); 209 210 /* 211 * Read a record and return the record layer version and record type in 212 * the |rversion| and |type| parameters. |*data| is set to point to a 213 * record layer buffer containing the record payload data and |*datalen| 214 * is filled in with the length of that data. The |epoch| and |seq_num| 215 * values are only used if DTLS has been negotiated. In that case they are 216 * filled in with the epoch and sequence number from the record. 217 * An opaque record layer handle for the record is returned in |*rechandle| 218 * which is used in a subsequent call to |release_record|. The buffer must 219 * remain available until all the bytes from record are released via one or 220 * more release_record calls. 221 * 222 * Internally the OSSL_RECORD_METHOD implementation may read/process 223 * multiple records in one go and buffer them. 224 */ 225 int (*read_record)(OSSL_RECORD_LAYER *rl, void **rechandle, int *rversion, 226 uint8_t *type, const unsigned char **data, size_t *datalen, 227 uint16_t *epoch, unsigned char *seq_num); 228 /* 229 * Release length bytes from a buffer associated with a record previously 230 * read with read_record. Once all the bytes from a record are released, the 231 * whole record and its associated buffer is released. Records are 232 * guaranteed to be released in the order that they are read. 233 */ 234 int (*release_record)(OSSL_RECORD_LAYER *rl, void *rechandle, size_t length); 235 236 /* 237 * In the event that a fatal error is returned from the functions above then 238 * get_alert_code() can be called to obtain a more details identifier for 239 * the error. In (D)TLS this is the alert description code. 240 */ 241 int (*get_alert_code)(OSSL_RECORD_LAYER *rl); 242 243 /* 244 * Update the transport BIO from the one originally set in the 245 * new_record_layer call 246 */ 247 int (*set1_bio)(OSSL_RECORD_LAYER *rl, BIO *bio); 248 249 /* Called when protocol negotiation selects a protocol version to use */ 250 int (*set_protocol_version)(OSSL_RECORD_LAYER *rl, int version); 251 252 /* 253 * Whether we are allowed to receive unencrypted alerts, even if we might 254 * otherwise expect encrypted records. Ignored by protocol versions where 255 * this isn't relevant 256 */ 257 void (*set_plain_alerts)(OSSL_RECORD_LAYER *rl, int allow); 258 259 /* 260 * Called immediately after creation of the record layer if we are in a 261 * first handshake. Also called at the end of the first handshake 262 */ 263 void (*set_first_handshake)(OSSL_RECORD_LAYER *rl, int first); 264 265 /* 266 * Set the maximum number of pipelines that the record layer should process. 267 * The default is 1. 268 */ 269 void (*set_max_pipelines)(OSSL_RECORD_LAYER *rl, size_t max_pipelines); 270 271 /* 272 * Called to tell the record layer whether we are currently "in init" or 273 * not. Default at creation of the record layer is "yes". 274 */ 275 void (*set_in_init)(OSSL_RECORD_LAYER *rl, int in_init); 276 277 /* 278 * Get a short or long human readable description of the record layer state 279 */ 280 void (*get_state)(OSSL_RECORD_LAYER *rl, const char **shortstr, 281 const char **longstr); 282 283 /* 284 * Set new options or modify ones that were originally specified in the 285 * new_record_layer call. 286 */ 287 int (*set_options)(OSSL_RECORD_LAYER *rl, const OSSL_PARAM *options); 288 289 const COMP_METHOD *(*get_compression)(OSSL_RECORD_LAYER *rl); 290 291 /* 292 * Set the maximum fragment length to be used for the record layer. This 293 * will override any previous value supplied for the "max_frag_len" 294 * setting during construction of the record layer. 295 */ 296 void (*set_max_frag_len)(OSSL_RECORD_LAYER *rl, size_t max_frag_len); 297 298 /* 299 * The maximum expansion in bytes that the record layer might add while 300 * writing a record 301 */ 302 size_t (*get_max_record_overhead)(OSSL_RECORD_LAYER *rl); 303 304 /* 305 * Increment the record sequence number 306 */ 307 int (*increment_sequence_ctr)(OSSL_RECORD_LAYER *rl); 308 309 /* 310 * Allocate read or write buffers. Does nothing if already allocated. 311 * Assumes default buffer length and 1 pipeline. 312 */ 313 int (*alloc_buffers)(OSSL_RECORD_LAYER *rl); 314 315 /* 316 * Free read or write buffers. Fails if there is pending read or write 317 * data. Buffers are automatically reallocated on next read/write. 318 */ 319 int (*free_buffers)(OSSL_RECORD_LAYER *rl); 320 }; 321 322 /* Standard built-in record methods */ 323 extern const OSSL_RECORD_METHOD ossl_tls_record_method; 324 #ifndef OPENSSL_NO_KTLS 325 extern const OSSL_RECORD_METHOD ossl_ktls_record_method; 326 #endif 327 extern const OSSL_RECORD_METHOD ossl_dtls_record_method; 328 329 #endif /* !defined(OSSL_INTERNAL_RECORDMETHOD_H) */ 330