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38 .Nd symmetric cryptographic operations
40 .In opencrypto/cryptodev.h
42 .Fn crypto_dispatch "struct cryptop *crp"
44 .Fn crypto_destroyreq "struct cryptop *crp"
46 .Fn crypto_freereq "struct cryptop *crp"
47 .Ft "struct cryptop *"
48 .Fn crypto_getreq "crypto_session_t cses" "int how"
50 .Fn crypto_initreq "crypto_session_t cses" "int how"
52 .Fn crypto_use_buf "struct cryptop *crp" "void *buf" "int len"
54 .Fn crypto_use_mbuf "struct cryptop *crp" "struct mbuf *m"
56 .Fn crypto_use_uio "struct cryptop *crp" "struct uio *uio"
58 .Fn crypto_use_output_buf "struct cryptop *crp" "void *buf" "int len"
60 .Fn crypto_use_output_mbuf "struct cryptop *crp" "struct mbuf *m"
62 .Fn crypto_use_output_uio "struct cryptop *crp" "struct uio *uio"
64 Each symmetric cryptographic operation in the kernel is described by
67 and is associated with an active session.
69 Requests can either be allocated dynamically or use caller-supplied
71 Dynamically allocated requests should be allocated by
75 once the request has completed.
76 Requests using caller-supplied storage should be initialized by
78 at the start of each operation and destroyed by
80 once the request has completed.
87 is a reference to an active session.
93 and should be set to either
98 Once a request has been initialized,
99 the caller should set fields in the structure to describe
100 request-specific parameters.
101 Unused fields should be left as-is.
104 passes a crypto request to the driver attached to the request's session.
105 If there are errors in the request's fields, this function may return
106 an error to the caller.
107 If errors are encountered while servicing the request, they will instead
108 be reported to the request's callback function
113 Note that a request's callback function may be invoked before
117 Once a request has signaled completion by invoking its callback function,
118 it should be freed via
119 .Fn crypto_destroyreq
123 Cryptographic operations include several fields to describe the request.
125 Requests can either specify a single data buffer that is modified in place
138 Note that separate input and output buffers are not supported for compression
141 All requests must have a valid
143 initialized by one of the following functions:
144 .Bl -tag -width "Fn crypto_use_mbuf"
145 .It Fn crypto_use_buf
151 .It Fn crypto_use_mbuf
152 Uses the network memory buffer
155 .It Fn crypto_use_uio
156 Uses the scatter/gather list
161 One of the following functions should be used to initialize
163 for requests that use separate input and output buffers:
164 .Bl -tag -width "Fn crypto_use_output_mbuf"
165 .It Fn crypto_use_output_buf
170 as the output buffer.
171 .It Fn crypto_use_output_mbuf
172 Uses the network memory buffer
174 as the output buffer.
175 .It Fn crypto_use_output_uio
176 Uses the scatter/gather list
178 as the output buffer.
181 Each request describes one or more regions in the data buffers.
182 Each region is described by an offset relative to the start of a
183 data buffer and a length.
184 The length of some regions is the same for all requests belonging to
186 Those lengths are set in the session parameters of the associated
188 All requests must define a payload region.
189 Other regions are only required for specific session modes.
191 For requests with separate input and output data buffers,
192 the AAD, IV, and payload regions are always defined as regions in the
194 and a separate payload output region is defined to hold the output of
195 encryption or decryption in the output buffer.
196 The digest region describes a region in the input data buffer for
197 requests that verify an existing digest.
198 For requests that compute a digest,
199 the digest region describes a region in the output data buffer.
200 Note that the only data written to the output buffer is the encryption
201 or decryption result and any computed digest.
202 AAD and IV regions are not copied from the input buffer into the output
203 buffer but are only used as inputs.
205 The following regions are defined:
206 .Bl -column "Payload Output" "Input/Output"
207 .It Sy Region Ta Sy Buffer Ta Sy Description
209 Embedded Additional Authenticated Data
212 .It Payload Ta Input Ta
213 Data to encrypt, decrypt, compress, or decompress
214 .It Payload Output Ta Output Ta
215 Encrypted or decrypted data
216 .It Digest Ta Input/Output Ta
217 Authentication digest, hash, or tag
219 .Bl -column "Payload Output" ".Fa crp_payload_output_start"
220 .It Sy Region Ta Sy Start Ta Sy Length
221 .It AAD Ta Fa crp_aad_start Ta Fa crp_aad_length
222 .It IV Ta Fa crp_iv_start Ta Fa csp_ivlen
223 .It Payload Ta Fa crp_payload_start Ta Fa crp_payload_length
224 .It Payload Output Ta Fa crp_payload_output_start Ta Fa crp_payload_length
225 .It Digest Ta Fa crp_digest_start Ta Fa csp_auth_mlen
228 Requests are permitted to operate on only a subset of the data buffer.
230 requests from IPsec operate on network packets that include headers not
231 used as either additional authentication data (AAD) or payload data.
232 .Ss Request Operations
233 All requests must specify the type of operation to perform in
235 Available operations depend on the session's mode.
237 Compression requests support the following operations:
238 .Bl -tag -width CRYPTO_OP_DECOMPRESS
239 .It Dv CRYPTO_OP_COMPRESS
240 Compress the data in the payload region of the data buffer.
241 .It Dv CRYPTO_OP_DECOMPRESS
242 Decompress the data in the payload region of the data buffer.
245 Cipher requests support the following operations:
246 .Bl -tag -width CRYPTO_OP_DECRYPT
247 .It Dv CRYPTO_OP_ENCRYPT
248 Encrypt the data in the payload region of the data buffer.
249 .It Dv CRYPTO_OP_DECRYPT
250 Decrypt the data in the payload region of the data buffer.
253 Digest requests support the following operations:
254 .Bl -tag -width CRYPTO_OP_COMPUTE_DIGEST
255 .It Dv CRYPTO_OP_COMPUTE_DIGEST
256 Calculate a digest over the payload region of the data buffer
257 and store the result in the digest region.
258 .It Dv CRYPTO_OP_VERIFY_DIGEST
259 Calculate a digest over the payload region of the data buffer.
260 Compare the calculated digest to the existing digest from the digest region.
261 If the digests match,
262 complete the request successfully.
263 If the digests do not match,
264 fail the request with
268 AEAD and Encrypt-then-Authenticate requests support the following
270 .Bl -tag -width CRYPTO_OP
271 .It Dv CRYPTO_OP_ENCRYPT | Dv CRYPTO_OP_COMPUTE_DIGEST
272 Encrypt the data in the payload region of the data buffer.
273 Calculate a digest over the AAD and payload regions and store the
274 result in the data buffer.
275 .It Dv CRYPTO_OP_DECRYPT | Dv CRYPTO_OP_VERIFY_DIGEST
276 Calculate a digest over the AAD and payload regions of the data buffer.
277 Compare the calculated digest to the existing digest from the digest region.
278 If the digests match,
279 decrypt the payload region.
280 If the digests do not match,
281 fail the request with
285 AEAD and Encrypt-then-Authenticate requests may optionally include
286 Additional Authenticated Data.
287 AAD may either be supplied in the AAD region of the input buffer or
288 as a single buffer pointed to by
292 always indicates the amount of AAD in bytes.
293 .Ss Request IV and/or Nonce
294 Some cryptographic operations require an IV or nonce as an input.
295 An IV may be stored either in the IV region of the data buffer or in
298 the IV is assumed to be stored in the IV region.
299 If the IV is stored in
301 .Dv CRYPTO_F_IV_SEPARATE
306 should be left as zero.
308 Requests that store part, but not all, of the IV in the data buffer should
309 store the partial IV in the data buffer and pass the full IV separately in
311 .Ss Request and Callback Scheduling
312 The crypto framework provides multiple methods of scheduling the dispatch
313 of requests to drivers along with the processing of driver callbacks.
314 Requests use flags in
316 to select the desired scheduling methods.
319 can pass the request to the session's driver via three different methods:
322 The request is queued to a taskqueue backed by a pool of worker threads.
323 By default the pool is sized to provide one thread for each CPU.
324 Worker threads dequeue requests and pass them to the driver
327 The request is passed to the driver synchronously in the context of the
329 .Fn crypto_dispatch .
331 The request is queued to a queue of pending requests.
332 A single worker thread dequeues requests and passes them to the driver
336 To select the first method (taskqueue backed by multiple threads),
339 To always use the third method (queue to single worker thread),
342 If both flags are set,
345 If neither flag is set,
347 will first attempt the second method (invoke driver synchronously).
348 If the driver is blocked,
349 the request will be queued using the third method.
350 One caveat is that the first method is only used for requests using software
351 drivers which use host CPUs to process requests.
352 Requests whose session is associated with a hardware driver will ignore
356 to determine how requests should be scheduled.
358 In addition to bypassing synchronous dispatch in
359 .Fn crypto_dispatch ,
361 requests additional changes aimed at optimizing batches of requests to
363 When the worker thread processes a request with
365 it will search the pending request queue for any other requests for the same
367 including requests from different sessions.
368 If any other requests are present,
370 is passed to the driver's process method.
371 Drivers may use this to batch completion interrupts.
373 Callback function scheduling is simpler than request scheduling.
374 Callbacks can either be invoked synchronously from
376 or they can be queued to a pool of worker threads.
377 This pool of worker threads is also sized to provide one worker thread
378 for each CPU by default.
379 Note that a callback function invoked synchronously from
381 must follow the same restrictions placed on threaded interrupt handlers.
384 callbacks are invoked asynchronously by a worker thread.
388 the callback is always invoked synchronously from
391 .Dv CRYPTO_F_CBIFSYNC
393 the callback is invoked synchronously if the request was processed by a
394 software driver or asynchronously if the request was processed by a
397 If a request was scheduled to the taskqueue via
399 callbacks are always invoked asynchronously ignoring
402 .Dv CRYPTO_F_CBIFSYNC .
404 .Dv CRYPTO_F_ASYNC_KEEPORDER
405 may be set to ensure that callbacks for requests on a given session are
406 invoked in the same order that requests were queued to the session via
407 .Fn crypto_dispatch .
408 This flag is used by IPsec to ensure that decrypted network packets are
409 passed up the network stack in roughly the same order they were received.
411 .Ss Other Request Fields
412 In addition to the fields and flags enumerated above,
414 includes the following:
415 .Bl -tag -width crp_payload_length
417 A reference to the active session.
418 This is set when the request is created by
420 and should not be modified.
421 Drivers can use this to fetch driver-specific session state or
425 Either zero on success, or an error if a request fails.
426 Set by drivers prior to completing a request via
430 The following flags are available in addition to flags discussed previously:
431 .Bl -tag -width CRYPTO_F_DONE
437 This flag is not very useful and will likely be removed in the future.
438 It can only be safely checked from the callback routine at which point
441 .It Fa crp_cipher_key
442 Pointer to a request-specific encryption key.
443 If this value is not set,
444 the request uses the session encryption key.
446 Pointer to a request-specific authentication key.
447 If this value is not set,
448 the request uses the session authentication key.
451 This pointer permits users of the cryptographic framework to store
452 information about a request to be used in the callback.
455 This must point to a callback function of type
456 .Vt void (*)(struct cryptop *) .
457 The callback function should inspect
459 to determine the status of the completed operation.
460 It should also arrange for the request to be freed via
463 Used with compression and decompression requests to describe the updated
464 length of the payload region in the data buffer.
466 If a compression request increases the size of the payload,
467 then the data buffer is unmodified, the request completes successfully,
470 is set to the size the compressed data would have used.
471 Callers can compare this to the payload region length to determine if
472 the compressed data was discarded.
476 returns an error if the request contained invalid fields,
477 or zero if the request was valid.
479 returns a pointer to a new request structure on success,
484 can only be returned if
492 .Xr crypto_session 9 ,
496 Not all drivers properly handle mixing session and per-request keys
497 within a single session.
498 Consumers should either use a single key for a session specified in
499 the session parameters or always use per-request keys.