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 #include <openssl/ssl.h>
  11
  12 /*
  13  * We use the term "record" here to refer to a packet of data. Records are
  14  * typically protected via a cipher and MAC, or an AEAD cipher (although not
  15  * always). This usage of the term record is consistent with the TLS concept.
  16  * In QUIC the term "record" is not used but it is analogous to the QUIC term
  17  * "packet". The interface in this file applies to all protocols that protect
  18  * records/packets of data, i.e. (D)TLS and QUIC. The term record is used to
  19  * refer to both contexts.
  20  */
  21
  22
  23 /*
  24  * Types of QUIC record layer;
  25  *
  26  * QUIC reuses the TLS handshake for agreeing secrets. An SSL object representing
  27  * a QUIC connection will have an additional SSL object internally representing
  28  * the TLS state of the QUIC handshake. This internal TLS is referred to as
  29  * QUIC-TLS in this file.
  30  * "Records" output from QUIC-TLS contains standard TLS handshake messages and
  31  * are *not* encrypted directly but are instead wrapped up in plaintext
  32  * CRYPTO frames. These CRYPTO frames could be collected together with other
  33  * QUIC frames into a single QUIC packet. The QUIC record layer will then
  34  * encrypt the whole packet.
  35  *
  36  * So we have:
  37  * QUIC-TLS record layer: outputs plaintext CRYPTO frames containing TLS
  38  *                        handshake messages only.
  39  * QUIC record layer: outputs encrypted packets which may contain CRYPTO frames
  40  *                    or any other type of QUIC frame.
  41  */
  42
  43 /*
  44  * An OSSL_RECORD_METHOD is a protcol specific method which provides the
  45  * functions for reading and writing records for that protocol. Which
  46  * OSSL_RECORD_METHOD to use for a given protocol is defined by the SSL_METHOD.
  47  */
  48 typedef struct ossl_record_method_st OSSL_RECORD_METHOD;
  49
  50 /*
  51  * An OSSL_RECORD_LAYER is just an externally defined opaque pointer created by
  52  * the method
  53  */
  54 typedef struct ossl_record_layer_st OSSL_RECORD_LAYER;
  55
  56
  57 #define OSSL_RECORD_ROLE_CLIENT 0
  58 #define OSSL_RECORD_ROLE_SERVER 1
  59
  60 #define OSSL_RECORD_DIRECTION_READ  0
  61 #define OSSL_RECORD_DIRECTION_WRITE 1
  62
  63 /*
  64  * Protection level. For <= TLSv1.2 only "NONE" and "APPLICATION" are used.
  65  */
  66 #define OSSL_RECORD_PROTECTION_LEVEL_NONE        0
  67 #define OSSL_RECORD_PROTECTION_LEVEL_EARLY       1
  68 #define OSSL_RECORD_PROTECTION_LEVEL_HANDSHAKE   2
  69 #define OSSL_RECORD_PROTECTION_LEVEL_APPLICATION 3
  70
  71
  72 #define OSSL_RECORD_RETURN_SUCCESS           1
  73 #define OSSL_RECORD_RETURN_RETRY             0
  74 #define OSSL_RECORD_RETURN_NON_FATAL_ERR    -1
  75 #define OSSL_RECORD_RETURN_FATAL            -2
  76 #define OSSL_RECORD_RETURN_EOF              -3
  77
  78 /*
  79  * Template for creating a record. A record consists of the |type| of data it
  80  * will contain (e.g. alert, handshake, application data, etc) along with an
  81  * array of buffers in |bufs| of size |numbufs|. There is a corresponding array
  82  * of buffer lengths in |buflens|. Concatenating all of the buffer data together
  83  * would give you the complete plaintext payload to be sent in a single record.
  84  */
  85 struct ossl_record_template_st {
  86     int type;
  87     void **bufs;
  88     size_t *buflens;
  89     size_t numbufs;
  90 };
  91
  92 typedef struct ossl_record_template_st OSSL_RECORD_TEMPLATE;
  93
  94 /*
  95  * Rather than a "method" approach, we could make this fetchable - Should we?
  96  * There could be some complexity in finding suitable record layer implementations
  97  * e.g. we need to find one that matches the negotiated protocol, cipher,
  98  * extensions, etc. The selection_cb approach given above doesn't work so well
  99  * if unknown third party providers with OSSL_RECORD_METHOD implementations are
 100  * loaded.
 101  */
 102
 103 /*
 104  * If this becomes public API then we will need functions to create and
 105  * free an OSSL_RECORD_METHOD, as well as functions to get/set the various
 106  * function pointers....unless we make it fetchable.
 107  */
 108 struct ossl_record_method_st {
 109     /*
 110      * Create a new OSSL_RECORD_LAYER object for handling the protocol version
 111      * set by |vers|. |role| is 0 for client and 1 for server. |direction|
 112      * indicates either read or write. |level| is the protection level as
 113      * described above. |settings| are mandatory settings that will cause the
 114      * new() call to fail if they are not understood (for example to require
 115      * Encrypt-Then-Mac support). |options| are optional settings that will not
 116      * cause the new() call to fail if they are not understood (for example
 117      * whether to use "read ahead" or not).
 118      *
 119      * The BIO in |transport| is the BIO for the underlying transport layer.
 120      * Where the direction is "read", then this BIO will only ever be used for
 121      * reading data. Where the direction is "write", then this BIO will only
 122      * every be used for writing data.
 123      *
 124      * An SSL object will always have at least 2 OSSL_RECORD_LAYER objects in
 125      * force at any one time (one for reading and one for writing). In some
 126      * protocols more than 2 might be used (e.g. in DTLS for retransmitting
 127      * messages from an earlier epoch).
 128      */
 129
 130     /*
 131      * TODO(RECLAYER): Will have to be something other than EVP_CIPHER if we
 132      * make this fetchable
 133      * TODO(RECLAYER): mactype should not be an int
 134      */
 135     OSSL_RECORD_LAYER *(*new_record_layer)(OSSL_LIB_CTX *libctx,
 136                                            const char *propq, int vers,
 137                                            int role, int direction,
 138                                            int level, unsigned char *key,
 139                                            size_t keylen,
 140                                            unsigned char *iv,
 141                                            size_t ivlen,
 142                                            unsigned char *mackey,
 143                                            size_t mackeylen,
 144                                            const EVP_CIPHER *ciph,
 145                                            size_t taglen,
 146                                            /* TODO(RECLAYER): This probably should not be an int */
 147                                            int mactype,
 148                                            const EVP_MD *md,
 149                                            const SSL_COMP *comp,
 150                                            BIO *transport, BIO_ADDR *local,
 151                                            BIO_ADDR *peer,
 152                                            const OSSL_PARAM *settings,
 153                                            const OSSL_PARAM *options,
 154                                            /* TODO(RECLAYER): Remove me */
 155                                            SSL_CONNECTION *s);
 156     void (*free)(OSSL_RECORD_LAYER *rl);
 157
 158     int (*reset)(OSSL_RECORD_LAYER *rl); /* Is this needed? */
 159
 160     /* Returns 1 if we have unprocessed data buffered or 0 otherwise */
 161     int (*unprocessed_read_pending)(OSSL_RECORD_LAYER *rl);
 162     /*
 163      * Returns 1 if we have processed data buffered that can be read or 0 otherwise
 164      * - not necessarily app data
 165      */
 166     int (*processed_read_pending)(OSSL_RECORD_LAYER *rl);
 167
 168     /*
 169      * The amount of processed app data that is internally bufferred and
 170      * available to read
 171      */
 172     size_t (*app_data_pending)(OSSL_RECORD_LAYER *rl);
 173
 174     int (*write_pending)(OSSL_RECORD_LAYER *rl);
 175
 176
 177     /*
 178      * Find out the maximum amount of plaintext data that the record layer is
 179      * prepared to write in a single record. When calling write_records it is
 180      * the caller's responsibility to ensure that no record template exceeds
 181      * this maximum when calling write_records.
 182      */
 183     size_t (*get_max_record_len)(OSSL_RECORD_LAYER *rl);
 184
 185     /*
 186      * Find out the maximum number of records that the record layer is prepared
 187      * to process in a single call to write_records. It is the caller's
 188      * responsibility to ensure that no call to write_records exceeds this
 189      * number of records.
 190      */
 191     size_t (*get_max_records)(OSSL_RECORD_LAYER *rl);
 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      * |allowance| is the maximum amount of "on-the-wire" data that is allowed
 199      * to be sent at the moment (including all QUIC headers, but excluding any
 200      * UDP/IP headers). After a successful or retry return |*sent| will
 201      * be updated with the amount of data that has been sent so far. In the case
 202      * of a retry this could be 0.
 203      * Where possible the caller will attempt to ensure that all records are the
 204      * same length, except the last record. This may not always be possible so
 205      * the record method implementation should not rely on this being the case.
 206      * In the event of a retry the caller should call retry_write_records()
 207      * to try again. No more calls to write_records() should be attempted until
 208      * retry_write_records() returns success.
 209      * Buffers allocated for the record templates can be freed immediately after
 210      * write_records() returns - even in the case a retry.
 211      * The record templates represent the plaintext payload. The encrypted
 212      * output is written to the |transport| BIO.
 213      * Returns:
 214      *  1 on success
 215      *  0 on retry
 216      * -1 on failure
 217      */
 218     int (*write_records)(OSSL_RECORD_LAYER *rl, OSSL_RECORD_TEMPLATE **templates,
 219                          size_t numtempl, size_t allowance, size_t *sent);
 220
 221     /*
 222      * Retry a previous call to write_records. The caller should continue to
 223      * call this until the function returns with success or failure. After
 224      * each retry more of the data may have been incrementally sent. |allowance|
 225      * is the amount of "on-the-wire" data that is allowed to be sent at the
 226      * moment. After a successful or retry return |*sent| will
 227      * be updated with the amount of data that has been sent by this call to
 228      * retry_write_records().
 229      * Returns:
 230      *  1 on success
 231      *  0 on retry
 232      * -1 on failure
 233      */
 234     int (*retry_write_records)(OSSL_RECORD_LAYER *rl, size_t allowance,
 235                                size_t *sent);
 236
 237     /*
 238      * Read a record and return the record layer version and record type in
 239      * the |rversion| and |type| parameters. |*data| is set to point to a
 240      * record layer buffer containing the record payload data and |*datalen|
 241      * is filled in with the length of that data. The |epoch| and |seq_num|
 242      * values are only used if DTLS has been negotiated. In that case they are
 243      * filled in with the epoch and sequence number from the record.
 244      * An opaque record layer handle for the record is returned in |*rechandle|
 245      * which is used in a subsequent call to |release_record|. The buffer must
 246      * remain available until release_record is called.
 247      *
 248      * Internally the the OSSL_RECORD_METHOD the implementation may read/process
 249      * multiple records in one go and buffer them.
 250      */
 251     int (*read_record)(OSSL_RECORD_LAYER *rl, void **rechandle, int *rversion,
 252                       int *type, unsigned char **data, size_t *datalen,
 253                       uint16_t *epoch, unsigned char *seq_num,
 254                       /* TODO(RECLAYER): Remove me */ SSL_CONNECTION *s);
 255     /*
 256      * Release a buffer associated with a record previously read with
 257      * read_record. Records are guaranteed to be released in the order that they
 258      * are read.
 259      */
 260     int (*release_record)(OSSL_RECORD_LAYER *rl, void *rechandle);
 261
 262     /*
 263      * In the event that a fatal error is returned from the functions above then
 264      * get_alert_code() can be called to obtain a more details identifier for
 265      * the error. In (D)TLS this is the alert description code.
 266      */
 267     int (*get_alert_code)(OSSL_RECORD_LAYER *rl);
 268
 269     /*
 270      * Update the transport BIO from the one originally set in the
 271      * new_record_layer call
 272      */
 273     int (*set1_bio)(OSSL_RECORD_LAYER *rl, BIO *bio);
 274
 275     /*
 276      * TODO(RECLAYER): Remove these. These function pointers are temporary hacks
 277      * during the record layer refactoring. They need to be removed before the
 278      * refactor is complete.
 279      */
 280     int (*read_n)(OSSL_RECORD_LAYER *rl, size_t n, size_t max, int extend,
 281                   int clearold, size_t *readbytes);
 282     SSL3_BUFFER *(*get0_rbuf)(OSSL_RECORD_LAYER *rl);
 283     unsigned char *(*get0_packet)(OSSL_RECORD_LAYER *rl);
 284     void (*set0_packet)(OSSL_RECORD_LAYER *rl, unsigned char *packet,
 285                         size_t packetlen);
 286     size_t (*get_packet_length)(OSSL_RECORD_LAYER *rl);
 287     void (*reset_packet_length)(OSSL_RECORD_LAYER *rl);
 288 };
 289
 290
 291 /* Standard built-in record methods */
 292 extern const OSSL_RECORD_METHOD ossl_tls_record_method;
 293 extern const OSSL_RECORD_METHOD ossl_dtls_record_method;