1 .\" $OpenBSD: crypto.9,v 1.19 2002/07/16 06:31:57 angelos Exp $
3 .\" The author of this manual page is Angelos D. Keromytis (angelos@cis.upenn.edu)
5 .\" Copyright (c) 2000, 2001 Angelos D. Keromytis
7 .\" Permission to use, copy, and modify this software with or without fee
8 .\" is hereby granted, provided that this entire notice is included in
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10 .\" modification of this software.
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25 .Nd API for cryptographic services in the kernel
27 .In opencrypto/cryptodev.h
29 .Fn crypto_get_driverid u_int8_t
31 .Fn crypto_register u_int32_t int u_int16_t u_int32_t "int \*[lp]*\*[rp]\*[lp]void *, u_int32_t *, struct cryptoini *\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, u_int64_t\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, struct cryptop *\*[rp]" "void *"
33 .Fn crypto_kregister u_int32_t int u_int32_t "int \*[lp]*\*[rp]\*[lp]void *, struct cryptkop *\*[rp]" "void *"
35 .Fn crypto_unregister u_int32_t int
37 .Fn crypto_unregister_all u_int32_t
39 .Fn crypto_done "struct cryptop *"
41 .Fn crypto_kdone "struct cryptkop *"
43 .Fn crypto_newsession "u_int64_t *" "struct cryptoini *" int
45 .Fn crypto_freesession u_int64_t
47 .Fn crypto_dispatch "struct cryptop *"
49 .Fn crypto_kdispatch "struct cryptkop *"
51 .Fn crypto_unblock u_int32_t int
52 .Ft "struct cryptop *"
55 .Fn crypto_freereq void
57 #define CRYPTO_SYMQ 0x1
58 #define CRYPTO_ASYMQ 0x2
60 #define EALG_MAX_BLOCK_LEN 16
67 u_int8_t cri_iv[EALG_MAX_BLOCK_LEN];
68 struct cryptoini *cri_next;
76 struct cryptoini CRD_INI;
77 #define crd_iv CRD_INI.cri_iv
78 #define crd_key CRD_INI.cri_key
79 #define crd_alg CRD_INI.cri_alg
80 #define crd_klen CRD_INI.cri_klen
81 struct cryptodesc *crd_next;
85 TAILQ_ENTRY(cryptop) crp_next;
93 struct cryptodesc *crp_desc;
94 int (*crp_callback) (struct cryptop *);
103 #define CRK_MAXPARAM 8
106 TAILQ_ENTRY(cryptkop) krp_next;
107 u_int krp_op; /* ie. CRK_MOD_EXP or other */
108 u_int krp_status; /* return status */
109 u_short krp_iparams; /* # of input parameters */
110 u_short krp_oparams; /* # of output parameters */
112 struct crparam krp_param[CRK_MAXPARAM];
113 int (*krp_callback)(struct cryptkop *);
118 is a framework for drivers of cryptographic hardware to register with
121 (other kernel subsystems, and
124 device) are able to make use of it.
125 Drivers register with the framework the algorithms they support,
126 and provide entry points (functions) the framework may call to
127 establish, use, and tear down sessions.
128 Sessions are used to cache cryptographic information in a particular driver
129 (or associated hardware), so initialization is not needed with every request.
130 Consumers of cryptographic services pass a set of
131 descriptors that instruct the framework (and the drivers registered
132 with it) of the operations that should be applied on the data (more
133 than one cryptographic operation can be requested).
135 Keying operations are supported as well.
136 Unlike the symmetric operators described above,
137 these sessionless commands perform mathematical operations using
138 input and output parameters.
140 Since the consumers may not be associated with a process, drivers may
143 The same holds for the framework.
144 Thus, a callback mechanism is used
145 to notify a consumer that a request has been completed (the
146 callback is specified by the consumer on an per-request basis).
147 The callback is invoked by the framework whether the request was
148 successfully completed or not.
149 An error indication is provided in the latter case.
150 A specific error code,
152 is used to indicate that a session number has changed and that the
153 request may be re-submitted immediately with the new session number.
154 Errors are only returned to the invoking function if not
155 enough information to call the callback is available (meaning, there
156 was a fatal error in verifying the arguments).
157 For session initialization and teardown there is no callback mechanism used.
160 .Fn crypto_newsession
161 routine is called by consumers of cryptographic services (such as the
163 stack) that wish to establish a new session with the framework.
164 On success, the first argument will contain the Session Identifier (SID).
165 The second argument contains all the necessary information for
166 the driver to establish the session.
167 The third argument indicates whether a
168 hardware driver (1) should be used or not (0).
169 The various fields in the
172 .Bl -tag -width ".Va cri_next"
174 Contains an algorithm identifier.
175 Currently supported algorithms are:
177 .Bl -tag -width ".Dv CRYPTO_RIPEMD160_HMAC" -compact
178 .It Dv CRYPTO_DES_CBC
179 .It Dv CRYPTO_3DES_CBC
180 .It Dv CRYPTO_BLF_CBC
181 .It Dv CRYPTO_CAST_CBC
182 .It Dv CRYPTO_SKIPJACK_CBC
183 .It Dv CRYPTO_MD5_HMAC
184 .It Dv CRYPTO_SHA1_HMAC
185 .It Dv CRYPTO_RIPEMD160_HMAC
186 .It Dv CRYPTO_MD5_KPDK
187 .It Dv CRYPTO_SHA1_KPDK
188 .It Dv CRYPTO_AES_CBC
192 .It Dv CRYPTO_SHA2_256_HMAC
193 .It Dv CRYPTO_SHA2_384_HMAC
194 .It Dv CRYPTO_SHA2_512_HMAC
195 .It Dv CRYPTO_NULL_HMAC
196 .It Dv CRYPTO_NULL_CBC
199 Specifies the length of the key in bits, for variable-size key
202 Specifies how many bytes from the calculated hash should be copied back.
205 Contains the key to be used with the algorithm.
207 Contains an explicit initialization vector (IV), if it does not prefix
209 This field is ignored during initialization.
210 If no IV is explicitly passed (see below on details), a random IV is used
211 by the device driver processing the request.
213 Contains a pointer to another
216 Multiple such structures may be linked to establish multi-algorithm sessions
218 is an example consumer of such a feature).
223 structure and its contents will not be modified by the framework (or
225 Subsequent requests for processing that use the
226 SID returned will avoid the cost of re-initializing the hardware (in
227 essence, SID acts as an index in the session cache of the driver).
229 .Fn crypto_freesession
230 is called with the SID returned by
231 .Fn crypto_newsession
232 to disestablish the session.
235 is called to process a request.
236 The various fields in the
239 .Bl -tag -width ".Va crp_callback"
243 Indicates the total length in bytes of the buffer to be processed.
245 On return, contains the total length of the result.
246 For symmetric crypto operations, this will be the same as the input length.
247 This will be used if the framework needs to allocate a new
248 buffer for the result (or for re-formatting the input).
250 This routine is invoked upon completion of the request, whether
252 It is invoked through the
255 If the request was not successful, an error code is set in the
258 It is the responsibility of the callback routine to set the appropriate
262 Contains the error type, if any errors were encountered, or zero if
263 the request was successfully processed.
266 error code is returned, the SID has changed (and has been recorded in the
269 The consumer should record the new SID and use it in all subsequent requests.
270 In this case, the request may be re-submitted immediately.
271 This mechanism is used by the framework to perform
272 session migration (move a session from one driver to another, because
273 of availability, performance, or other considerations).
275 Note that this field only makes sense when examined by
276 the callback routine specified in
278 Errors are returned to the invoker of
280 only when enough information is not present to call the callback
281 routine (i.e., if the pointer passed is
283 or if no callback routine was specified).
285 Is a bitmask of flags associated with this request.
286 Currently defined flags are:
287 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
288 .It Dv CRYPTO_F_IMBUF
289 The buffer pointed to by
293 The buffer pointed to by
299 Must return data in the same place.
300 .It Dv CRYPTO_F_BATCH
301 Batch operation if possible.
302 .It Dv CRYPTO_F_CBIMM
303 Do callback immediately instead of doing it from a dedicated kernel thread.
306 .It Dv CRYPTO_F_CBIFSYNC
307 Do callback immediately if operation is synchronous.
310 Points to the input buffer.
311 On return (when the callback is invoked),
312 it contains the result of the request.
313 The input buffer may be an mbuf
314 chain or a contiguous buffer,
318 This is passed through the crypto framework untouched and is
319 intended for the invoking application's use.
321 This is a linked list of descriptors.
322 Each descriptor provides
323 information about what type of cryptographic operation should be done
325 The various fields are:
326 .Bl -tag -width ".Va crd_inject"
328 The field where IV should be provided when the
329 .Dv CRD_F_IV_EXPLICIT
333 .Dv CRD_F_KEY_EXPLICIT
336 points to a buffer with encryption or authentication key.
339 Must be the same as the one given at newsession time.
345 The offset in the input buffer where processing should start.
347 How many bytes, after
351 Offset from the beginning of the buffer to insert any results.
352 For encryption algorithms, this is where the initialization vector
353 (IV) will be inserted when encrypting or where it can be found when
354 decrypting (subject to
356 For MAC algorithms, this is where the result of the keyed hash will be
359 The following flags are defined:
362 For encryption algorithms, this bit is set when encryption is required
363 (when not set, decryption is performed).
364 .It Dv CRD_F_IV_PRESENT
365 For encryption algorithms, this bit is set when the IV already
366 precedes the data, so the
368 value will be ignored and no IV will be written in the buffer.
369 Otherwise, the IV used to encrypt the packet will be written
370 at the location pointed to by
372 The IV length is assumed to be equal to the blocksize of the
373 encryption algorithm.
374 Some applications that do special
376 such as the half-IV mode in
378 can use this flag to indicate that the IV should not be written on the packet.
379 This flag is typically used in conjunction with the
380 .Dv CRD_F_IV_EXPLICIT
382 .It Dv CRD_F_IV_EXPLICIT
383 For encryption algorithms, this bit is set when the IV is explicitly
384 provided by the consumer in the
387 Otherwise, for encryption operations the IV is provided for by
388 the driver used to perform the operation, whereas for decryption
389 operations it is pointed to by the
392 This flag is typically used when the IV is calculated
394 by the consumer, and does not precede the data (some
396 configurations, and the encrypted swap are two such examples).
397 .It Dv CRD_F_KEY_EXPLICIT
398 For encryption and authentication (MAC) algorithms, this bit is set when the key
399 is explicitly provided by the consumer in the
401 field for the given operation.
402 Otherwise, the key is taken at newsession time from the
406 For compression algorithms, this bit is set when compression is required (when
407 not set, decompression is performed).
412 structure will not be modified by the framework or the device drivers.
413 Since this information accompanies every cryptographic
414 operation request, drivers may re-initialize state on-demand
415 (typically an expensive operation).
416 Furthermore, the cryptographic
417 framework may re-route requests as a result of full queues or hardware
418 failure, as described above.
420 Point to the next descriptor.
421 Linked operations are useful in protocols such as
423 where multiple cryptographic transforms may be applied on the same
431 structure with a linked list of as many
433 structures as were specified in the argument passed to it.
436 deallocates a structure
440 structures linked to it.
441 Note that it is the responsibility of the
442 callback routine to do the necessary cleanups associated with the
448 is called to perform a keying operation.
449 The various fields in the
452 .Bl -tag -width ".Va krp_callback'
454 Operation code, such as
460 variable indicates whether lower level reasons
461 for operation failure.
463 Number if input parameters to the specified operation.
464 Note that each operation has a (typically hardwired) number of such parameters.
466 Number if output parameters from the specified operation.
467 Note that each operation has a (typically hardwired) number of such parameters.
469 An array of kernel memory blocks containing the parameters.
471 Identifier specifying which low-level driver is being used.
473 Callback called on completion of a keying operation.
477 .Fn crypto_get_driverid ,
478 .Fn crypto_register ,
479 .Fn crypto_kregister ,
480 .Fn crypto_unregister ,
484 routines are used by drivers that provide support for cryptographic
485 primitives to register and unregister with the kernel crypto services
487 Drivers must first use the
488 .Fn crypto_get_driverid
489 function to acquire a driver identifier, specifying the
491 as an argument (normally 0, but software-only drivers should specify
492 .Dv CRYPTOCAP_F_SOFTWARE ) .
493 For each algorithm the driver supports, it must then call
494 .Fn crypto_register .
495 The first two arguments are the driver and algorithm identifiers.
496 The next two arguments specify the largest possible operator length (in bits,
497 important for public key operations) and flags for this algorithm.
498 The last four arguments must be provided in the first call to
500 and are ignored in all subsequent calls.
501 They are pointers to three
502 driver-provided functions that the framework may call to establish new
503 cryptographic context with the driver, free already established
504 context, and ask for a request to be processed (encrypt, decrypt,
505 etc.); and an opaque parameter to pass when calling each of these routines.
506 .Fn crypto_unregister
507 is called by drivers that wish to withdraw support for an algorithm.
508 The two arguments are the driver and algorithm identifiers, respectively.
509 Typically, drivers for
511 crypto cards that are being ejected will invoke this routine for all
512 algorithms supported by the card.
513 .Fn crypto_unregister_all
514 will unregister all algorithms registered by a driver
515 and the driver will be disabled (no new sessions will be allocated on
516 that driver, and any existing sessions will be migrated to other
518 The same will be done if all algorithms associated with a driver are
519 unregistered one by one.
521 The calling convention for the three driver-supplied routines is:
526 .Fn \*[lp]*newsession\*[rp] "void *" "u_int32_t *" "struct cryptoini *" ;
529 .Fn \*[lp]*freesession\*[rp] "void *" "u_int64_t" ;
532 .Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ;
535 .Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ;
538 On invocation, the first argument to
539 all routines is an opaque data value supplied when the algorithm
541 .Fn crypto_register .
542 The second argument to
544 contains the driver identifier obtained via
545 .Fn crypto_get_driverid .
546 On successful return, it should contain a driver-specific session
548 The third argument is identical to that of
549 .Fn crypto_newsession .
553 routine takes as arguments the opaque data value and the SID
554 (which is the concatenation of the
555 driver identifier and the driver-specific session identifier).
556 It should clear any context associated with the session (clear hardware
557 registers, memory, etc.).
561 routine is invoked with a request to perform crypto processing.
562 This routine must not block, but should queue the request and return
564 Upon processing the request, the callback routine should be invoked.
565 In case of an unrecoverable error, the error indication must be placed in the
570 When the request is completed, or an error is detected, the
572 routine should invoke
574 Session migration may be performed, as mentioned previously.
576 In case of a temporary resource exhaustion, the
580 in which case the crypto services will requeue the request, mark the driver
583 and stop submitting requests for processing.
584 The driver is then responsible for notifying the crypto services
585 when it is again able to process requests through the
588 This simple flow control mechanism should only be used for short-lived
589 resource exhaustion as it causes operations to be queued in the crypto
591 Doing so is preferable to returning an error in such cases as
592 it can cause network protocols to degrade performance by treating the
593 failure much like a lost packet.
597 routine is invoked with a request to perform crypto key processing.
598 This routine must not block, but should queue the request and return
600 Upon processing the request, the callback routine should be invoked.
601 In case of an unrecoverable error, the error indication must be placed in the
606 When the request is completed, or an error is detected, the
608 routine should invoked
611 .Fn crypto_register ,
612 .Fn crypto_kregister ,
613 .Fn crypto_unregister ,
614 .Fn crypto_newsession ,
615 .Fn crypto_freesession ,
618 return 0 on success, or an error code on failure.
619 .Fn crypto_get_driverid
620 returns a non-negative value on error, and \-1 on failure.
622 returns a pointer to a
630 if its argument or the callback function was
633 The callback is provided with an error code in case of failure, in the
637 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
638 .It Pa sys/opencrypto/crypto.c
639 most of the framework code
646 The cryptographic framework first appeared in
649 .An "Angelos D. Keromytis" Aq angelos@openbsd.org .
651 The framework currently assumes that all the algorithms in a
652 .Fn crypto_newsession
653 operation must be available by the same driver.
654 If that is not the case, session initialization will fail.
656 The framework also needs a mechanism for determining which driver is
657 best for a specific set of algorithms associated with a session.
658 Some type of benchmarking is in order here.
660 Multiple instances of the same algorithm in the same session are not
662 Note that 3DES is considered one algorithm (and not three
664 Thus, 3DES and DES could be mixed in the same request.