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
9 .\" all source code copies of any software which is or includes a copy or
10 .\" modification of this software.
12 .\" THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
13 .\" IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
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20 .Dd September 19, 2007
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 a 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_AES_CBC
180 .It Dv CRYPTO_BLF_CBC
181 .It Dv CRYPTO_CAMELLIA_CBC
182 .It Dv CRYPTO_CAST_CBC
183 .It Dv CRYPTO_DES_CBC
184 .It Dv CRYPTO_3DES_CBC
185 .It Dv CRYPTO_SKIPJACK_CBC
187 .It Dv CRYPTO_MD5_HMAC
188 .It Dv CRYPTO_MD5_KPDK
189 .It Dv CRYPTO_RIPEMD160_HMAC
191 .It Dv CRYPTO_SHA1_HMAC
192 .It Dv CRYPTO_SHA1_KPDK
193 .It Dv CRYPTO_SHA2_256_HMAC
194 .It Dv CRYPTO_SHA2_384_HMAC
195 .It Dv CRYPTO_SHA2_512_HMAC
196 .It Dv CRYPTO_NULL_HMAC
197 .It Dv CRYPTO_NULL_CBC
200 Specifies the length of the key in bits, for variable-size key
203 Specifies how many bytes from the calculated hash should be copied back.
206 Contains the key to be used with the algorithm.
208 Contains an explicit initialization vector (IV), if it does not prefix
210 This field is ignored during initialization.
211 If no IV is explicitly passed (see below on details), a random IV is used
212 by the device driver processing the request.
214 Contains a pointer to another
217 Multiple such structures may be linked to establish multi-algorithm sessions
219 is an example consumer of such a feature).
224 structure and its contents will not be modified by the framework (or
226 Subsequent requests for processing that use the
227 SID returned will avoid the cost of re-initializing the hardware (in
228 essence, SID acts as an index in the session cache of the driver).
230 .Fn crypto_freesession
231 is called with the SID returned by
232 .Fn crypto_newsession
233 to disestablish the session.
236 is called to process a request.
237 The various fields in the
240 .Bl -tag -width ".Va crp_callback"
244 Indicates the total length in bytes of the buffer to be processed.
246 On return, contains the total length of the result.
247 For symmetric crypto operations, this will be the same as the input length.
248 This will be used if the framework needs to allocate a new
249 buffer for the result (or for re-formatting the input).
251 This routine is invoked upon completion of the request, whether
253 It is invoked through the
256 If the request was not successful, an error code is set in the
259 It is the responsibility of the callback routine to set the appropriate
263 Contains the error type, if any errors were encountered, or zero if
264 the request was successfully processed.
267 error code is returned, the SID has changed (and has been recorded in the
270 The consumer should record the new SID and use it in all subsequent requests.
271 In this case, the request may be re-submitted immediately.
272 This mechanism is used by the framework to perform
273 session migration (move a session from one driver to another, because
274 of availability, performance, or other considerations).
276 Note that this field only makes sense when examined by
277 the callback routine specified in
279 Errors are returned to the invoker of
281 only when enough information is not present to call the callback
282 routine (i.e., if the pointer passed is
284 or if no callback routine was specified).
286 Is a bitmask of flags associated with this request.
287 Currently defined flags are:
288 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
289 .It Dv CRYPTO_F_IMBUF
290 The buffer pointed to by
294 The buffer pointed to by
300 Must return data in the same place.
301 .It Dv CRYPTO_F_BATCH
302 Batch operation if possible.
303 .It Dv CRYPTO_F_CBIMM
304 Do callback immediately instead of doing it from a dedicated kernel thread.
307 .It Dv CRYPTO_F_CBIFSYNC
308 Do callback immediately if operation is synchronous.
311 Points to the input buffer.
312 On return (when the callback is invoked),
313 it contains the result of the request.
314 The input buffer may be an mbuf
315 chain or a contiguous buffer,
319 This is passed through the crypto framework untouched and is
320 intended for the invoking application's use.
322 This is a linked list of descriptors.
323 Each descriptor provides
324 information about what type of cryptographic operation should be done
326 The various fields are:
327 .Bl -tag -width ".Va crd_inject"
329 The field where IV should be provided when the
330 .Dv CRD_F_IV_EXPLICIT
334 .Dv CRD_F_KEY_EXPLICIT
337 points to a buffer with encryption or authentication key.
340 Must be the same as the one given at newsession time.
346 The offset in the input buffer where processing should start.
348 How many bytes, after
352 Offset from the beginning of the buffer to insert any results.
353 For encryption algorithms, this is where the initialization vector
354 (IV) will be inserted when encrypting or where it can be found when
355 decrypting (subject to
357 For MAC algorithms, this is where the result of the keyed hash will be
360 The following flags are defined:
363 For encryption algorithms, this bit is set when encryption is required
364 (when not set, decryption is performed).
365 .It Dv CRD_F_IV_PRESENT
366 For encryption algorithms, this bit is set when the IV already
367 precedes the data, so the
369 value will be ignored and no IV will be written in the buffer.
370 Otherwise, the IV used to encrypt the packet will be written
371 at the location pointed to by
373 The IV length is assumed to be equal to the blocksize of the
374 encryption algorithm.
375 Some applications that do special
377 such as the half-IV mode in
379 can use this flag to indicate that the IV should not be written on the packet.
380 This flag is typically used in conjunction with the
381 .Dv CRD_F_IV_EXPLICIT
383 .It Dv CRD_F_IV_EXPLICIT
384 For encryption algorithms, this bit is set when the IV is explicitly
385 provided by the consumer in the
388 Otherwise, for encryption operations the IV is provided for by
389 the driver used to perform the operation, whereas for decryption
390 operations it is pointed to by the
393 This flag is typically used when the IV is calculated
395 by the consumer, and does not precede the data (some
397 configurations, and the encrypted swap are two such examples).
398 .It Dv CRD_F_KEY_EXPLICIT
399 For encryption and authentication (MAC) algorithms, this bit is set when the key
400 is explicitly provided by the consumer in the
402 field for the given operation.
403 Otherwise, the key is taken at newsession time from the
407 For compression algorithms, this bit is set when compression is required (when
408 not set, decompression is performed).
413 structure will not be modified by the framework or the device drivers.
414 Since this information accompanies every cryptographic
415 operation request, drivers may re-initialize state on-demand
416 (typically an expensive operation).
417 Furthermore, the cryptographic
418 framework may re-route requests as a result of full queues or hardware
419 failure, as described above.
421 Point to the next descriptor.
422 Linked operations are useful in protocols such as
424 where multiple cryptographic transforms may be applied on the same
432 structure with a linked list of as many
434 structures as were specified in the argument passed to it.
437 deallocates a structure
441 structures linked to it.
442 Note that it is the responsibility of the
443 callback routine to do the necessary cleanups associated with the
449 is called to perform a keying operation.
450 The various fields in the
453 .Bl -tag -width ".Va krp_callback'
455 Operation code, such as
461 variable indicates whether lower level reasons
462 for operation failure.
464 Number if input parameters to the specified operation.
465 Note that each operation has a (typically hardwired) number of such parameters.
467 Number if output parameters from the specified operation.
468 Note that each operation has a (typically hardwired) number of such parameters.
470 An array of kernel memory blocks containing the parameters.
472 Identifier specifying which low-level driver is being used.
474 Callback called on completion of a keying operation.
478 .Fn crypto_get_driverid ,
479 .Fn crypto_register ,
480 .Fn crypto_kregister ,
481 .Fn crypto_unregister ,
485 routines are used by drivers that provide support for cryptographic
486 primitives to register and unregister with the kernel crypto services
488 Drivers must first use the
489 .Fn crypto_get_driverid
490 function to acquire a driver identifier, specifying the
492 as an argument (normally 0, but software-only drivers should specify
493 .Dv CRYPTOCAP_F_SOFTWARE ) .
494 For each algorithm the driver supports, it must then call
495 .Fn crypto_register .
496 The first two arguments are the driver and algorithm identifiers.
497 The next two arguments specify the largest possible operator length (in bits,
498 important for public key operations) and flags for this algorithm.
499 The last four arguments must be provided in the first call to
501 and are ignored in all subsequent calls.
502 They are pointers to three
503 driver-provided functions that the framework may call to establish new
504 cryptographic context with the driver, free already established
505 context, and ask for a request to be processed (encrypt, decrypt,
506 etc.); and an opaque parameter to pass when calling each of these routines.
507 .Fn crypto_unregister
508 is called by drivers that wish to withdraw support for an algorithm.
509 The two arguments are the driver and algorithm identifiers, respectively.
510 Typically, drivers for
512 crypto cards that are being ejected will invoke this routine for all
513 algorithms supported by the card.
514 .Fn crypto_unregister_all
515 will unregister all algorithms registered by a driver
516 and the driver will be disabled (no new sessions will be allocated on
517 that driver, and any existing sessions will be migrated to other
519 The same will be done if all algorithms associated with a driver are
520 unregistered one by one.
522 The calling convention for the three driver-supplied routines is:
527 .Fn \*[lp]*newsession\*[rp] "void *" "u_int32_t *" "struct cryptoini *" ;
530 .Fn \*[lp]*freesession\*[rp] "void *" "u_int64_t" ;
533 .Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ;
536 .Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ;
539 On invocation, the first argument to
540 all routines is an opaque data value supplied when the algorithm
542 .Fn crypto_register .
543 The second argument to
545 contains the driver identifier obtained via
546 .Fn crypto_get_driverid .
547 On successful return, it should contain a driver-specific session
549 The third argument is identical to that of
550 .Fn crypto_newsession .
554 routine takes as arguments the opaque data value and the SID
555 (which is the concatenation of the
556 driver identifier and the driver-specific session identifier).
557 It should clear any context associated with the session (clear hardware
558 registers, memory, etc.).
562 routine is invoked with a request to perform crypto processing.
563 This routine must not block, but should queue the request and return
565 Upon processing the request, the callback routine should be invoked.
566 In case of an unrecoverable error, the error indication must be placed in the
571 When the request is completed, or an error is detected, the
573 routine should invoke
575 Session migration may be performed, as mentioned previously.
577 In case of a temporary resource exhaustion, the
581 in which case the crypto services will requeue the request, mark the driver
584 and stop submitting requests for processing.
585 The driver is then responsible for notifying the crypto services
586 when it is again able to process requests through the
589 This simple flow control mechanism should only be used for short-lived
590 resource exhaustion as it causes operations to be queued in the crypto
592 Doing so is preferable to returning an error in such cases as
593 it can cause network protocols to degrade performance by treating the
594 failure much like a lost packet.
598 routine is invoked with a request to perform crypto key processing.
599 This routine must not block, but should queue the request and return
601 Upon processing the request, the callback routine should be invoked.
602 In case of an unrecoverable error, the error indication must be placed in the
607 When the request is completed, or an error is detected, the
609 routine should invoked
612 .Fn crypto_register ,
613 .Fn crypto_kregister ,
614 .Fn crypto_unregister ,
615 .Fn crypto_newsession ,
616 .Fn crypto_freesession ,
619 return 0 on success, or an error code on failure.
620 .Fn crypto_get_driverid
621 returns a non-negative value on error, and \-1 on failure.
623 returns a pointer to a
631 if its argument or the callback function was
634 The callback is provided with an error code in case of failure, in the
638 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
639 .It Pa sys/opencrypto/crypto.c
640 most of the framework code
647 The cryptographic framework first appeared in
650 .An "Angelos D. Keromytis" Aq angelos@openbsd.org .
652 The framework currently assumes that all the algorithms in a
653 .Fn crypto_newsession
654 operation must be available by the same driver.
655 If that is not the case, session initialization will fail.
657 The framework also needs a mechanism for determining which driver is
658 best for a specific set of algorithms associated with a session.
659 Some type of benchmarking is in order here.
661 Multiple instances of the same algorithm in the same session are not
663 Note that 3DES is considered one algorithm (and not three
665 Thus, 3DES and DES could be mixed in the same request.