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
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8 .\" is hereby granted, provided that this entire notice is included in
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25 .Nd API for cryptographic services in the kernel
27 .In opencrypto/cryptodev.h
29 .Fn crypto_get_driverid uint8_t
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_newsession "uint64_t *" "struct cryptoini *" int
45 .Fn crypto_freesession uint64_t
47 .Fn crypto_dispatch "struct cryptop *"
49 .Fn crypto_kdispatch "struct cryptkop *"
51 .Fn crypto_unblock uint32_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 uint8_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_128_NIST_GMAC
179 .It Dv CRYPTO_AES_192_NIST_GMAC
180 .It Dv CRYPTO_AES_256_NIST_GMAC
181 .It Dv CRYPTO_AES_CBC
182 .It Dv CRYPTO_AES_ICM
183 .It Dv CRYPTO_AES_NIST_GCM_16
184 .It Dv CRYPTO_AES_NIST_GMAC
185 .It Dv CRYPTO_AES_XTS
187 .It Dv CRYPTO_BLF_CBC
188 .It Dv CRYPTO_CAMELLIA_CBC
189 .It Dv CRYPTO_CAST_CBC
190 .It Dv CRYPTO_DEFLATE_COMP
191 .It Dv CRYPTO_DES_CBC
192 .It Dv CRYPTO_3DES_CBC
194 .It Dv CRYPTO_MD5_HMAC
195 .It Dv CRYPTO_MD5_KPDK
196 .It Dv CRYPTO_NULL_HMAC
197 .It Dv CRYPTO_NULL_CBC
198 .It Dv CRYPTO_RIPEMD160_HMAC
200 .It Dv CRYPTO_SHA1_HMAC
201 .It Dv CRYPTO_SHA1_KPDK
202 .It Dv CRYPTO_SHA2_256_HMAC
203 .It Dv CRYPTO_SHA2_384_HMAC
204 .It Dv CRYPTO_SHA2_512_HMAC
205 .It Dv CRYPTO_SKIPJACK_CBC
208 Specifies the length of the key in bits, for variable-size key
211 Specifies how many bytes from the calculated hash should be copied back.
214 Contains the key to be used with the algorithm.
216 Contains an explicit initialization vector (IV), if it does not prefix
218 This field is ignored during initialization
219 .Pq Nm crypto_newsession .
220 If no IV is explicitly passed (see below on details), a random IV is used
221 by the device driver processing the request.
223 Contains a pointer to another
226 Multiple such structures may be linked to establish multi-algorithm sessions
228 is an example consumer of such a feature).
233 structure and its contents will not be modified by the framework (or
235 Subsequent requests for processing that use the
236 SID returned will avoid the cost of re-initializing the hardware (in
237 essence, SID acts as an index in the session cache of the driver).
239 .Fn crypto_freesession
240 is called with the SID returned by
241 .Fn crypto_newsession
242 to disestablish the session.
245 is called to process a request.
246 The various fields in the
249 .Bl -tag -width ".Va crp_callback"
253 Indicates the total length in bytes of the buffer to be processed.
255 On return, contains the total length of the result.
256 For symmetric crypto operations, this will be the same as the input length.
257 This will be used if the framework needs to allocate a new
258 buffer for the result (or for re-formatting the input).
260 This routine is invoked upon completion of the request, whether
262 It is invoked through the
265 If the request was not successful, an error code is set in the
268 It is the responsibility of the callback routine to set the appropriate
272 Contains the error type, if any errors were encountered, or zero if
273 the request was successfully processed.
276 error code is returned, the SID has changed (and has been recorded in the
279 The consumer should record the new SID and use it in all subsequent requests.
280 In this case, the request may be re-submitted immediately.
281 This mechanism is used by the framework to perform
282 session migration (move a session from one driver to another, because
283 of availability, performance, or other considerations).
285 Note that this field only makes sense when examined by
286 the callback routine specified in
288 Errors are returned to the invoker of
290 only when enough information is not present to call the callback
291 routine (i.e., if the pointer passed is
293 or if no callback routine was specified).
295 Is a bitmask of flags associated with this request.
296 Currently defined flags are:
297 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
298 .It Dv CRYPTO_F_IMBUF
299 The buffer pointed to by
303 The buffer pointed to by
308 .It Dv CRYPTO_F_BATCH
309 Batch operation if possible.
310 .It Dv CRYPTO_F_CBIMM
311 Do callback immediately instead of doing it from a dedicated kernel thread.
314 .It Dv CRYPTO_F_CBIFSYNC
315 Do callback immediately if operation is synchronous.
318 Points to the input buffer.
319 On return (when the callback is invoked),
320 it contains the result of the request.
321 The input buffer may be an mbuf
322 chain or a contiguous buffer,
326 This is passed through the crypto framework untouched and is
327 intended for the invoking application's use.
329 This is a linked list of descriptors.
330 Each descriptor provides
331 information about what type of cryptographic operation should be done
333 The various fields are:
334 .Bl -tag -width ".Va crd_inject"
336 The field where IV should be provided when the
337 .Dv CRD_F_IV_EXPLICIT
341 .Dv CRD_F_KEY_EXPLICIT
344 points to a buffer with encryption or authentication key.
347 Must be the same as the one given at newsession time.
353 The offset in the input buffer where processing should start.
355 How many bytes, after
359 Offset from the beginning of the buffer to insert any results.
360 For encryption algorithms, this is where the initialization vector
361 (IV) will be inserted when encrypting or where it can be found when
362 decrypting (subject to
364 For MAC algorithms, this is where the result of the keyed hash will be
367 The following flags are defined:
370 For encryption algorithms, this bit is set when encryption is required
371 (when not set, decryption is performed).
372 .It Dv CRD_F_IV_PRESENT
373 For encryption, this bit is set when the IV already
374 precedes the data, so the
376 value will be ignored and no IV will be written in the buffer.
377 Otherwise, the IV used to encrypt the packet will be written
378 at the location pointed to by
380 The IV length is assumed to be equal to the blocksize of the
381 encryption algorithm.
382 Applications that do special
384 such as the half-IV mode in
386 can use this flag to indicate that the IV should not be written on the packet.
387 This flag is typically used in conjunction with the
388 .Dv CRD_F_IV_EXPLICIT
390 .It Dv CRD_F_IV_EXPLICIT
391 For encryption algorithms, this bit is set when the IV is explicitly
392 provided by the consumer in the
395 Otherwise, for encryption operations the IV is provided for by
396 the driver used to perform the operation, whereas for decryption
397 operations it is pointed to by the
400 This flag is typically used when the IV is calculated
402 by the consumer, and does not precede the data (some
404 configurations, and the encrypted swap are two such examples).
405 .It Dv CRD_F_KEY_EXPLICIT
406 For encryption and authentication (MAC) algorithms, this bit is set when the key
407 is explicitly provided by the consumer in the
409 field for the given operation.
410 Otherwise, the key is taken at newsession time from the
413 As calculating the key schedule may take a while, it is recommended that often
414 used keys are given their own session.
416 For compression algorithms, this bit is set when compression is required (when
417 not set, decompression is performed).
422 structure will not be modified by the framework or the device drivers.
423 Since this information accompanies every cryptographic
424 operation request, drivers may re-initialize state on-demand
425 (typically an expensive operation).
426 Furthermore, the cryptographic
427 framework may re-route requests as a result of full queues or hardware
428 failure, as described above.
430 Point to the next descriptor.
431 Linked operations are useful in protocols such as
433 where multiple cryptographic transforms may be applied on the same
441 structure with a linked list of as many
443 structures as were specified in the argument passed to it.
446 deallocates a structure
450 structures linked to it.
451 Note that it is the responsibility of the
452 callback routine to do the necessary cleanups associated with the
458 is called to perform a keying operation.
459 The various fields in the
462 .Bl -tag -width ".Va krp_callback"
464 Operation code, such as
470 variable indicates whether lower level reasons
471 for operation failure.
473 Number if input parameters to the specified operation.
474 Note that each operation has a (typically hardwired) number of such parameters.
476 Number if output parameters from the specified operation.
477 Note that each operation has a (typically hardwired) number of such parameters.
479 An array of kernel memory blocks containing the parameters.
481 Identifier specifying which low-level driver is being used.
483 Callback called on completion of a keying operation.
487 .Fn crypto_get_driverid ,
488 .Fn crypto_register ,
489 .Fn crypto_kregister ,
490 .Fn crypto_unregister ,
494 routines are used by drivers that provide support for cryptographic
495 primitives to register and unregister with the kernel crypto services
497 Drivers must first use the
498 .Fn crypto_get_driverid
499 function to acquire a driver identifier, specifying the
501 as an argument (normally 0, but software-only drivers should specify
502 .Dv CRYPTOCAP_F_SOFTWARE ) .
503 For each algorithm the driver supports, it must then call
504 .Fn crypto_register .
505 The first two arguments are the driver and algorithm identifiers.
506 The next two arguments specify the largest possible operator length (in bits,
507 important for public key operations) and flags for this algorithm.
508 The last four arguments must be provided in the first call to
510 and are ignored in all subsequent calls.
511 They are pointers to three
512 driver-provided functions that the framework may call to establish new
513 cryptographic context with the driver, free already established
514 context, and ask for a request to be processed (encrypt, decrypt,
515 etc.); and an opaque parameter to pass when calling each of these routines.
516 .Fn crypto_unregister
517 is called by drivers that wish to withdraw support for an algorithm.
518 The two arguments are the driver and algorithm identifiers, respectively.
519 Typically, drivers for
521 crypto cards that are being ejected will invoke this routine for all
522 algorithms supported by the card.
523 .Fn crypto_unregister_all
524 will unregister all algorithms registered by a driver
525 and the driver will be disabled (no new sessions will be allocated on
526 that driver, and any existing sessions will be migrated to other
528 The same will be done if all algorithms associated with a driver are
529 unregistered one by one.
531 The calling convention for the three driver-supplied routines is:
536 .Fn \*[lp]*newsession\*[rp] "void *" "uint32_t *" "struct cryptoini *" ;
539 .Fn \*[lp]*freesession\*[rp] "void *" "uint64_t" ;
542 .Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ;
545 .Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ;
548 On invocation, the first argument to
549 all routines is an opaque data value supplied when the algorithm
551 .Fn crypto_register .
552 The second argument to
554 contains the driver identifier obtained via
555 .Fn crypto_get_driverid .
556 On successful return, it should contain a driver-specific session
558 The third argument is identical to that of
559 .Fn crypto_newsession .
563 routine takes as arguments the opaque data value and the SID
564 (which is the concatenation of the
565 driver identifier and the driver-specific session identifier).
566 It should clear any context associated with the session (clear hardware
567 registers, memory, etc.).
571 routine is invoked with a request to perform crypto processing.
572 This routine must not block, but should queue the request and return
574 Upon processing the request, the callback routine should be invoked.
575 In case of an unrecoverable error, the error indication must be placed in the
580 When the request is completed, or an error is detected, the
582 routine should invoke
584 Session migration may be performed, as mentioned previously.
586 In case of a temporary resource exhaustion, the
590 in which case the crypto services will requeue the request, mark the driver
593 and stop submitting requests for processing.
594 The driver is then responsible for notifying the crypto services
595 when it is again able to process requests through the
598 This simple flow control mechanism should only be used for short-lived
599 resource exhaustion as it causes operations to be queued in the crypto
601 Doing so is preferable to returning an error in such cases as
602 it can cause network protocols to degrade performance by treating the
603 failure much like a lost packet.
607 routine is invoked with a request to perform crypto key processing.
608 This routine must not block, but should queue the request and return
610 Upon processing the request, the callback routine should be invoked.
611 In case of an unrecoverable error, the error indication must be placed in the
616 When the request is completed, or an error is detected, the
618 routine should invoked
621 .Fn crypto_register ,
622 .Fn crypto_kregister ,
623 .Fn crypto_unregister ,
624 .Fn crypto_newsession ,
625 .Fn crypto_freesession ,
628 return 0 on success, or an error code on failure.
629 .Fn crypto_get_driverid
630 returns a non-negative value on error, and \-1 on failure.
632 returns a pointer to a
640 if its argument or the callback function was
643 The callback is provided with an error code in case of failure, in the
647 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
648 .It Pa sys/opencrypto/crypto.c
649 most of the framework code
658 The cryptographic framework first appeared in
661 .An Angelos D. Keromytis Aq Mt angelos@openbsd.org .
663 The framework currently assumes that all the algorithms in a
664 .Fn crypto_newsession
665 operation must be available by the same driver.
666 If that is not the case, session initialization will fail.
668 The framework also needs a mechanism for determining which driver is
669 best for a specific set of algorithms associated with a session.
670 Some type of benchmarking is in order here.
672 Multiple instances of the same algorithm in the same session are not
674 Note that 3DES is considered one algorithm (and not three
676 Thus, 3DES and DES could be mixed in the same request.