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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15 .\" MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
25 .Nd API for cryptographic services in the kernel
27 .In opencrypto/cryptodev.h
29 .Fn crypto_get_driverid device_t int
31 .Fn crypto_register uint32_t int uint16_t uint32_t "int \*[lp]*\*[rp]\*[lp]void *, uint32_t *, struct cryptoini *\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, uint64_t\*[rp]" "int \*[lp]*\*[rp]\*[lp]void *, struct cryptop *\*[rp]" "void *"
33 .Fn crypto_kregister uint32_t int uint32_t "int \*[lp]*\*[rp]\*[lp]void *, struct cryptkop *\*[rp]" "void *"
35 .Fn crypto_unregister uint32_t int
37 .Fn crypto_unregister_all uint32_t
39 .Fn crypto_done "struct cryptop *"
41 .Fn crypto_kdone "struct cryptkop *"
43 .Fn crypto_find_driver "const char *"
45 .Fn crypto_newsession "uint64_t *" "struct cryptoini *" int
47 .Fn crypto_freesession uint64_t
49 .Fn crypto_dispatch "struct cryptop *"
51 .Fn crypto_kdispatch "struct cryptkop *"
53 .Fn crypto_unblock uint32_t int
54 .Ft "struct cryptop *"
57 .Fn crypto_freereq void
59 #define CRYPTO_SYMQ 0x1
60 #define CRYPTO_ASYMQ 0x2
62 #define EALG_MAX_BLOCK_LEN 16
69 uint8_t cri_iv[EALG_MAX_BLOCK_LEN];
70 struct cryptoini *cri_next;
78 struct cryptoini CRD_INI;
79 #define crd_iv CRD_INI.cri_iv
80 #define crd_key CRD_INI.cri_key
81 #define crd_alg CRD_INI.cri_alg
82 #define crd_klen CRD_INI.cri_klen
83 struct cryptodesc *crd_next;
87 TAILQ_ENTRY(cryptop) crp_next;
95 struct cryptodesc *crp_desc;
96 int (*crp_callback) (struct cryptop *);
105 #define CRK_MAXPARAM 8
108 TAILQ_ENTRY(cryptkop) krp_next;
109 u_int krp_op; /* ie. CRK_MOD_EXP or other */
110 u_int krp_status; /* return status */
111 u_short krp_iparams; /* # of input parameters */
112 u_short krp_oparams; /* # of output parameters */
114 struct crparam krp_param[CRK_MAXPARAM];
115 int (*krp_callback)(struct cryptkop *);
120 is a framework for drivers of cryptographic hardware to register with
123 (other kernel subsystems, and
126 device) are able to make use of it.
127 Drivers register with the framework the algorithms they support,
128 and provide entry points (functions) the framework may call to
129 establish, use, and tear down sessions.
130 Sessions are used to cache cryptographic information in a particular driver
131 (or associated hardware), so initialization is not needed with every request.
132 Consumers of cryptographic services pass a set of
133 descriptors that instruct the framework (and the drivers registered
134 with it) of the operations that should be applied on the data (more
135 than one cryptographic operation can be requested).
137 Keying operations are supported as well.
138 Unlike the symmetric operators described above,
139 these sessionless commands perform mathematical operations using
140 input and output parameters.
142 Since the consumers may not be associated with a process, drivers may
145 The same holds for the framework.
146 Thus, a callback mechanism is used
147 to notify a consumer that a request has been completed (the
148 callback is specified by the consumer on a per-request basis).
149 The callback is invoked by the framework whether the request was
150 successfully completed or not.
151 An error indication is provided in the latter case.
152 A specific error code,
154 is used to indicate that a session number has changed and that the
155 request may be re-submitted immediately with the new session number.
156 Errors are only returned to the invoking function if not
157 enough information to call the callback is available (meaning, there
158 was a fatal error in verifying the arguments).
159 For session initialization and teardown there is no callback mechanism used.
162 .Fn crypto_find_driver
163 function may be called to return the specific id of the provided name.
164 If the specified driver could not be found, the returned id is -1.
167 .Fn crypto_newsession
168 routine is called by consumers of cryptographic services (such as the
170 stack) that wish to establish a new session with the framework.
171 The second argument contains all the necessary information for
172 the driver to establish the session.
173 The third argument is either a specific driver id, or one or both
175 .Dv CRYPTOCAP_F_HARDWARE ,
176 to select hardware devices,
178 .Dv CRYPTOCAP_F_SOFTWARE ,
179 to select software devices.
180 If both are specified, a hardware device will be returned
181 before a software device will be.
182 On success, the value pointed to by the first argument will be the
183 Session IDentifier (SID).
184 The various fields in the
187 .Bl -tag -width ".Va cri_next"
189 Contains an algorithm identifier.
190 Currently supported algorithms are:
192 .Bl -tag -width ".Dv CRYPTO_RIPEMD160_HMAC" -compact
193 .It Dv CRYPTO_AES_128_NIST_GMAC
194 .It Dv CRYPTO_AES_192_NIST_GMAC
195 .It Dv CRYPTO_AES_256_NIST_GMAC
196 .It Dv CRYPTO_AES_CBC
197 .It Dv CRYPTO_AES_ICM
198 .It Dv CRYPTO_AES_NIST_GCM_16
199 .It Dv CRYPTO_AES_NIST_GMAC
200 .It Dv CRYPTO_AES_XTS
202 .It Dv CRYPTO_BLF_CBC
203 .It Dv CRYPTO_CAMELLIA_CBC
204 .It Dv CRYPTO_CAST_CBC
205 .It Dv CRYPTO_DEFLATE_COMP
206 .It Dv CRYPTO_DES_CBC
207 .It Dv CRYPTO_3DES_CBC
209 .It Dv CRYPTO_MD5_HMAC
210 .It Dv CRYPTO_MD5_KPDK
211 .It Dv CRYPTO_NULL_HMAC
212 .It Dv CRYPTO_NULL_CBC
213 .It Dv CRYPTO_RIPEMD160_HMAC
215 .It Dv CRYPTO_SHA1_HMAC
216 .It Dv CRYPTO_SHA1_KPDK
217 .It Dv CRYPTO_SHA2_256_HMAC
218 .It Dv CRYPTO_SHA2_384_HMAC
219 .It Dv CRYPTO_SHA2_512_HMAC
220 .It Dv CRYPTO_SKIPJACK_CBC
223 Specifies the length of the key in bits, for variable-size key
226 Specifies how many bytes from the calculated hash should be copied back.
229 Contains the key to be used with the algorithm.
231 Contains an explicit initialization vector (IV), if it does not prefix
233 This field is ignored during initialization
234 .Pq Nm crypto_newsession .
235 If no IV is explicitly passed (see below on details), a random IV is used
236 by the device driver processing the request.
238 Contains a pointer to another
241 Multiple such structures may be linked to establish multi-algorithm sessions
243 is an example consumer of such a feature).
248 structure and its contents will not be modified by the framework (or
250 Subsequent requests for processing that use the
251 SID returned will avoid the cost of re-initializing the hardware (in
252 essence, SID acts as an index in the session cache of the driver).
254 .Fn crypto_freesession
255 is called with the SID returned by
256 .Fn crypto_newsession
257 to disestablish the session.
260 is called to process a request.
261 The various fields in the
264 .Bl -tag -width ".Va crp_callback"
268 Indicates the total length in bytes of the buffer to be processed.
270 On return, contains the total length of the result.
271 For symmetric crypto operations, this will be the same as the input length.
272 This will be used if the framework needs to allocate a new
273 buffer for the result (or for re-formatting the input).
275 This routine is invoked upon completion of the request, whether
277 It is invoked through the
280 If the request was not successful, an error code is set in the
283 It is the responsibility of the callback routine to set the appropriate
287 Contains the error type, if any errors were encountered, or zero if
288 the request was successfully processed.
291 error code is returned, the SID has changed (and has been recorded in the
294 The consumer should record the new SID and use it in all subsequent requests.
295 In this case, the request may be re-submitted immediately.
296 This mechanism is used by the framework to perform
297 session migration (move a session from one driver to another, because
298 of availability, performance, or other considerations).
300 Note that this field only makes sense when examined by
301 the callback routine specified in
303 Errors are returned to the invoker of
305 only when enough information is not present to call the callback
306 routine (i.e., if the pointer passed is
308 or if no callback routine was specified).
310 Is a bitmask of flags associated with this request.
311 Currently defined flags are:
312 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
313 .It Dv CRYPTO_F_IMBUF
314 The buffer pointed to by
318 The buffer pointed to by
323 .It Dv CRYPTO_F_BATCH
324 Batch operation if possible.
325 .It Dv CRYPTO_F_CBIMM
326 Do callback immediately instead of doing it from a dedicated kernel thread.
329 .It Dv CRYPTO_F_CBIFSYNC
330 Do callback immediately if operation is synchronous (that the driver
336 Points to the input buffer.
337 On return (when the callback is invoked),
338 it contains the result of the request.
339 The input buffer may be an mbuf
340 chain or a contiguous buffer,
344 This is passed through the crypto framework untouched and is
345 intended for the invoking application's use.
347 This is a linked list of descriptors.
348 Each descriptor provides
349 information about what type of cryptographic operation should be done
351 The various fields are:
352 .Bl -tag -width ".Va crd_inject"
355 .Dv CRD_F_IV_EXPLICIT
356 is set, this field contains the IV.
359 .Dv CRD_F_KEY_EXPLICIT
362 points to a buffer with encryption or authentication key.
365 Must be the same as the one given at newsession time.
371 The offset in the input buffer where processing should start.
373 How many bytes, after
379 field specifies an offset in bytes from the beginning of the buffer.
380 For encryption algorithms, this may be where the IV will be inserted
381 when encrypting or where the IV may be found for
382 decryption (subject to
384 For MAC algorithms, this is where the result of the keyed hash will be
387 The following flags are defined:
390 For encryption algorithms, this bit is set when encryption is required
391 (when not set, decryption is performed).
392 .It Dv CRD_F_IV_PRESENT
393 .\" This flag name has nothing to do w/ it's behavior, fix the name.
394 For encryption, if this bit is not set the IV used to encrypt the packet
395 will be written at the location pointed to by
397 The IV length is assumed to be equal to the blocksize of the
398 encryption algorithm.
399 For encryption, if this bit is set, nothing is done.
400 For decryption, this flag has no meaning.
401 Applications that do special
403 such as the half-IV mode in
405 can use this flag to indicate that the IV should not be written on the packet.
406 This flag is typically used in conjunction with the
407 .Dv CRD_F_IV_EXPLICIT
409 .It Dv CRD_F_IV_EXPLICIT
410 This bit is set when the IV is explicitly
411 provided by the consumer in the
414 Otherwise, for encryption operations the IV is provided for by
415 the driver used to perform the operation, whereas for decryption
416 operations the offset of the IV is provided by the
419 This flag is typically used when the IV is calculated
421 by the consumer, and does not precede the data (some
423 configurations, and the encrypted swap are two such examples).
424 .It Dv CRD_F_KEY_EXPLICIT
425 For encryption and authentication (MAC) algorithms, this bit is set when the key
426 is explicitly provided by the consumer in the
428 field for the given operation.
429 Otherwise, the key is taken at newsession time from the
432 As calculating the key schedule may take a while, it is recommended that often
433 used keys are given their own session.
435 For compression algorithms, this bit is set when compression is required (when
436 not set, decompression is performed).
441 structure will not be modified by the framework or the device drivers.
442 Since this information accompanies every cryptographic
443 operation request, drivers may re-initialize state on-demand
444 (typically an expensive operation).
445 Furthermore, the cryptographic
446 framework may re-route requests as a result of full queues or hardware
447 failure, as described above.
449 Point to the next descriptor.
450 Linked operations are useful in protocols such as
452 where multiple cryptographic transforms may be applied on the same
460 structure with a linked list of as many
462 structures as were specified in the argument passed to it.
465 deallocates a structure
469 structures linked to it.
470 Note that it is the responsibility of the
471 callback routine to do the necessary cleanups associated with the
477 is called to perform a keying operation.
478 The various fields in the
481 .Bl -tag -width ".Va krp_callback"
483 Operation code, such as
489 variable indicates whether lower level reasons
490 for operation failure.
492 Number if input parameters to the specified operation.
493 Note that each operation has a (typically hardwired) number of such parameters.
495 Number if output parameters from the specified operation.
496 Note that each operation has a (typically hardwired) number of such parameters.
498 An array of kernel memory blocks containing the parameters.
500 Identifier specifying which low-level driver is being used.
502 Callback called on completion of a keying operation.
506 .Fn crypto_get_driverid ,
507 .Fn crypto_register ,
508 .Fn crypto_kregister ,
509 .Fn crypto_unregister ,
513 routines are used by drivers that provide support for cryptographic
514 primitives to register and unregister with the kernel crypto services
517 Drivers must first use the
518 .Fn crypto_get_driverid
519 function to acquire a driver identifier, specifying the
523 .Dv CRYPTOCAP_F_SOFTWARE
525 .Dv CRYPTOCAP_F_HARDWARE
529 may also be specified, and should be specified if the driver does all of
530 it's operations synchronously.
532 For each algorithm the driver supports, it must then call
533 .Fn crypto_register .
534 The first two arguments are the driver and algorithm identifiers.
535 The next two arguments specify the largest possible operator length (in bits,
536 important for public key operations) and flags for this algorithm.
537 The last four arguments must be provided in the first call to
539 and are ignored in all subsequent calls.
540 They are pointers to three
541 driver-provided functions that the framework may call to establish new
542 cryptographic context with the driver, free already established
543 context, and ask for a request to be processed (encrypt, decrypt,
544 etc.); and an opaque parameter to pass when calling each of these routines.
546 .Fn crypto_unregister
547 is called by drivers that wish to withdraw support for an algorithm.
548 The two arguments are the driver and algorithm identifiers, respectively.
549 Typically, drivers for
551 crypto cards that are being ejected will invoke this routine for all
552 algorithms supported by the card.
553 .Fn crypto_unregister_all
554 will unregister all algorithms registered by a driver
555 and the driver will be disabled (no new sessions will be allocated on
556 that driver, and any existing sessions will be migrated to other
558 The same will be done if all algorithms associated with a driver are
559 unregistered one by one.
561 .Fn crypto_unregister_all
562 there will be no threads in either the newsession or freesession function
565 The calling convention for the three driver-supplied routines are:
570 .Fn \*[lp]*newsession\*[rp] "device_t" "uint32_t *" "struct cryptoini *" ;
573 .Fn \*[lp]*freesession\*[rp] "device_t" "uint64_t" ;
576 .Fn \*[lp]*process\*[rp] "device_t" "struct cryptop *" "int" ;
579 .Fn \*[lp]*kprocess\*[rp] "device_t" "struct cryptkop *" "int" ;
582 On invocation, the first argument to
586 .Fn crypto_get_driverid .
587 The second argument to
589 contains the driver identifier obtained via
590 .Fn crypto_get_driverid .
591 On successful return, it should contain a driver-specific session
593 The third argument is identical to that of
594 .Fn crypto_newsession .
598 routine takes as arguments the opaque data value and the SID
599 (which is the concatenation of the
600 driver identifier and the driver-specific session identifier).
601 It should clear any context associated with the session (clear hardware
602 registers, memory, etc.).
606 routine is invoked with a request to perform crypto processing.
607 This routine must not block or sleep, but should queue the request and return
608 immediately or process the request to completion.
609 In case of an unrecoverable error, the error indication must be placed in the
614 When the request is completed, or an error is detected, the
618 Session migration may be performed, as mentioned previously.
620 In case of a temporary resource exhaustion, the
624 in which case the crypto services will requeue the request, mark the driver
627 and stop submitting requests for processing.
628 The driver is then responsible for notifying the crypto services
629 when it is again able to process requests through the
632 This simple flow control mechanism should only be used for short-lived
633 resource exhaustion as it causes operations to be queued in the crypto
635 Doing so is preferable to returning an error in such cases as
636 it can cause network protocols to degrade performance by treating the
637 failure much like a lost packet.
641 routine is invoked with a request to perform crypto key processing.
642 This routine must not block, but should queue the request and return
644 Upon processing the request, the callback routine should be invoked.
645 In case of an unrecoverable error, the error indication must be placed in the
650 When the request is completed, or an error is detected, the
652 routine should invoked
655 .Fn crypto_register ,
656 .Fn crypto_kregister ,
657 .Fn crypto_unregister ,
658 .Fn crypto_newsession ,
659 .Fn crypto_freesession ,
662 return 0 on success, or an error code on failure.
663 .Fn crypto_get_driverid
664 returns a non-negative value on error, and \-1 on failure.
666 returns a pointer to a
674 if its argument or the callback function was
677 The callback is provided with an error code in case of failure, in the
681 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
682 .It Pa sys/opencrypto/crypto.c
683 most of the framework code
692 The cryptographic framework first appeared in
695 .An Angelos D. Keromytis Aq Mt angelos@openbsd.org .
697 The framework currently assumes that all the algorithms in a
698 .Fn crypto_newsession
699 operation must be available by the same driver.
700 If that is not the case, session initialization will fail.
702 The framework also needs a mechanism for determining which driver is
703 best for a specific set of algorithms associated with a session.
704 Some type of benchmarking is in order here.
706 Multiple instances of the same algorithm in the same session are not
708 Note that 3DES is considered one algorithm (and not three
710 Thus, 3DES and DES could be mixed in the same request.