1.\" $OpenBSD: crypto.9,v 1.19 2002/07/16 06:31:57 angelos Exp $ 2.\" 3.\" The author of this manual page is Angelos D. Keromytis (angelos@cis.upenn.edu) 4.\" 5.\" Copyright (c) 2000, 2001 Angelos D. Keromytis 6.\" 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. 11.\" 12.\" THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR 13.\" IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY 14.\" REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE 15.\" MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR 16.\" PURPOSE. 17.\" 18.\" $FreeBSD$ 19.\" 20.Dd July 10, 2015 21.Dt CRYPTO 9 22.Os 23.Sh NAME 24.Nm crypto 25.Nd API for cryptographic services in the kernel 26.Sh SYNOPSIS 27.In opencrypto/cryptodev.h 28.Ft int32_t 29.Fn crypto_get_driverid device_t int 30.Ft 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 *" 32.Ft int 33.Fn crypto_kregister uint32_t int uint32_t "int \*[lp]*\*[rp]\*[lp]void *, struct cryptkop *\*[rp]" "void *" 34.Ft int 35.Fn crypto_unregister uint32_t int 36.Ft int 37.Fn crypto_unregister_all uint32_t 38.Ft void 39.Fn crypto_done "struct cryptop *" 40.Ft void 41.Fn crypto_kdone "struct cryptkop *" 42.Ft int 43.Fn crypto_find_driver "const char *" 44.Ft int 45.Fn crypto_newsession "uint64_t *" "struct cryptoini *" int 46.Ft int 47.Fn crypto_freesession uint64_t 48.Ft int 49.Fn crypto_dispatch "struct cryptop *" 50.Ft int 51.Fn crypto_kdispatch "struct cryptkop *" 52.Ft int 53.Fn crypto_unblock uint32_t int 54.Ft "struct cryptop *" 55.Fn crypto_getreq int 56.Ft void 57.Fn crypto_freereq void 58.Bd -literal 59#define CRYPTO_SYMQ 0x1 60#define CRYPTO_ASYMQ 0x2 61 62#define EALG_MAX_BLOCK_LEN 16 63 64struct cryptoini { 65 int cri_alg; 66 int cri_klen; 67 int cri_mlen; 68 caddr_t cri_key; 69 uint8_t cri_iv[EALG_MAX_BLOCK_LEN]; 70 struct cryptoini *cri_next; 71}; 72 73struct cryptodesc { 74 int crd_skip; 75 int crd_len; 76 int crd_inject; 77 int crd_flags; 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; 84}; 85 86struct cryptop { 87 TAILQ_ENTRY(cryptop) crp_next; 88 uint64_t crp_sid; 89 int crp_ilen; 90 int crp_olen; 91 int crp_etype; 92 int crp_flags; 93 caddr_t crp_buf; 94 caddr_t crp_opaque; 95 struct cryptodesc *crp_desc; 96 int (*crp_callback) (struct cryptop *); 97 caddr_t crp_mac; 98}; 99 100struct crparam { 101 caddr_t crp_p; 102 u_int crp_nbits; 103}; 104 105#define CRK_MAXPARAM 8 106 107struct cryptkop { 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 */ 113 uint32_t krp_hid; 114 struct crparam krp_param[CRK_MAXPARAM]; 115 int (*krp_callback)(struct cryptkop *); 116}; 117.Ed 118.Sh DESCRIPTION 119.Nm 120is a framework for drivers of cryptographic hardware to register with 121the kernel so 122.Dq consumers 123(other kernel subsystems, and 124users through the 125.Pa /dev/crypto 126device) are able to make use of it. 127Drivers register with the framework the algorithms they support, 128and provide entry points (functions) the framework may call to 129establish, use, and tear down sessions. 130Sessions are used to cache cryptographic information in a particular driver 131(or associated hardware), so initialization is not needed with every request. 132Consumers of cryptographic services pass a set of 133descriptors that instruct the framework (and the drivers registered 134with it) of the operations that should be applied on the data (more 135than one cryptographic operation can be requested). 136.Pp 137Keying operations are supported as well. 138Unlike the symmetric operators described above, 139these sessionless commands perform mathematical operations using 140input and output parameters. 141.Pp 142Since the consumers may not be associated with a process, drivers may 143not 144.Xr sleep 9 . 145The same holds for the framework. 146Thus, a callback mechanism is used 147to notify a consumer that a request has been completed (the 148callback is specified by the consumer on a per-request basis). 149The callback is invoked by the framework whether the request was 150successfully completed or not. 151An error indication is provided in the latter case. 152A specific error code, 153.Er EAGAIN , 154is used to indicate that a session number has changed and that the 155request may be re-submitted immediately with the new session number. 156Errors are only returned to the invoking function if not 157enough information to call the callback is available (meaning, there 158was a fatal error in verifying the arguments). 159For session initialization and teardown there is no callback mechanism used. 160.Pp 161The 162.Fn crypto_find_driver 163function may be called to return the specific id of the provided name. 164If the specified driver could not be found, the returned id is -1. 165.Pp 166The 167.Fn crypto_newsession 168routine is called by consumers of cryptographic services (such as the 169.Xr ipsec 4 170stack) that wish to establish a new session with the framework. 171The second argument contains all the necessary information for 172the driver to establish the session. 173The third argument is either a specific driver id, or one or both 174of 175.Dv CRYPTOCAP_F_HARDWARE , 176to select hardware devices, 177or 178.Dv CRYPTOCAP_F_SOFTWARE , 179to select software devices. 180If both are specified, a hardware device will be returned 181before a software device will be. 182On success, the value pointed to by the first argument will be the 183Session IDentifier (SID). 184The various fields in the 185.Vt cryptoini 186structure are: 187.Bl -tag -width ".Va cri_next" 188.It Va cri_alg 189Contains an algorithm identifier. 190Currently supported algorithms are: 191.Pp 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 201.It Dv CRYPTO_ARC4 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 208.It Dv CRYPTO_MD5 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 214.It Dv CRYPTO_SHA1 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 221.El 222.It Va cri_klen 223Specifies the length of the key in bits, for variable-size key 224algorithms. 225.It Va cri_mlen 226Specifies how many bytes from the calculated hash should be copied back. 2270 means entire hash. 228.It Va cri_key 229Contains the key to be used with the algorithm. 230.It Va cri_iv 231Contains an explicit initialization vector (IV), if it does not prefix 232the data. 233This field is ignored during initialization 234.Pq Nm crypto_newsession . 235If no IV is explicitly passed (see below on details), a random IV is used 236by the device driver processing the request. 237.It Va cri_next 238Contains a pointer to another 239.Vt cryptoini 240structure. 241Multiple such structures may be linked to establish multi-algorithm sessions 242.Xr ( ipsec 4 243is an example consumer of such a feature). 244.El 245.Pp 246The 247.Vt cryptoini 248structure and its contents will not be modified by the framework (or 249the drivers used). 250Subsequent requests for processing that use the 251SID returned will avoid the cost of re-initializing the hardware (in 252essence, SID acts as an index in the session cache of the driver). 253.Pp 254.Fn crypto_freesession 255is called with the SID returned by 256.Fn crypto_newsession 257to disestablish the session. 258.Pp 259.Fn crypto_dispatch 260is called to process a request. 261The various fields in the 262.Vt cryptop 263structure are: 264.Bl -tag -width ".Va crp_callback" 265.It Va crp_sid 266Contains the SID. 267.It Va crp_ilen 268Indicates the total length in bytes of the buffer to be processed. 269.It Va crp_olen 270On return, contains the total length of the result. 271For symmetric crypto operations, this will be the same as the input length. 272This will be used if the framework needs to allocate a new 273buffer for the result (or for re-formatting the input). 274.It Va crp_callback 275This routine is invoked upon completion of the request, whether 276successful or not. 277It is invoked through the 278.Fn crypto_done 279routine. 280If the request was not successful, an error code is set in the 281.Va crp_etype 282field. 283It is the responsibility of the callback routine to set the appropriate 284.Xr spl 9 285level. 286.It Va crp_etype 287Contains the error type, if any errors were encountered, or zero if 288the request was successfully processed. 289If the 290.Er EAGAIN 291error code is returned, the SID has changed (and has been recorded in the 292.Va crp_sid 293field). 294The consumer should record the new SID and use it in all subsequent requests. 295In this case, the request may be re-submitted immediately. 296This mechanism is used by the framework to perform 297session migration (move a session from one driver to another, because 298of availability, performance, or other considerations). 299.Pp 300Note that this field only makes sense when examined by 301the callback routine specified in 302.Va crp_callback . 303Errors are returned to the invoker of 304.Fn crypto_process 305only when enough information is not present to call the callback 306routine (i.e., if the pointer passed is 307.Dv NULL 308or if no callback routine was specified). 309.It Va crp_flags 310Is a bitmask of flags associated with this request. 311Currently defined flags are: 312.Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC" 313.It Dv CRYPTO_F_IMBUF 314The buffer pointed to by 315.Va crp_buf 316is an mbuf chain. 317.It Dv CRYPTO_F_IOV 318The buffer pointed to by 319.Va crp_buf 320is an 321.Vt uio 322structure. 323.It Dv CRYPTO_F_BATCH 324Batch operation if possible. 325.It Dv CRYPTO_F_CBIMM 326Do callback immediately instead of doing it from a dedicated kernel thread. 327.It Dv CRYPTO_F_DONE 328Operation completed. 329.It Dv CRYPTO_F_CBIFSYNC 330Do callback immediately if operation is synchronous (that the driver 331specified the 332.Dv CRYPTOCAP_F_SYNC 333flag). 334.El 335.It Va crp_buf 336Points to the input buffer. 337On return (when the callback is invoked), 338it contains the result of the request. 339The input buffer may be an mbuf 340chain or a contiguous buffer, 341depending on 342.Va crp_flags . 343.It Va crp_opaque 344This is passed through the crypto framework untouched and is 345intended for the invoking application's use. 346.It Va crp_desc 347This is a linked list of descriptors. 348Each descriptor provides 349information about what type of cryptographic operation should be done 350on the input buffer. 351The various fields are: 352.Bl -tag -width ".Va crd_inject" 353.It Va crd_iv 354When the flag 355.Dv CRD_F_IV_EXPLICIT 356is set, this field contains the IV. 357.It Va crd_key 358When the 359.Dv CRD_F_KEY_EXPLICIT 360flag is set, the 361.Va crd_key 362points to a buffer with encryption or authentication key. 363.It Va crd_alg 364An algorithm to use. 365Must be the same as the one given at newsession time. 366.It Va crd_klen 367The 368.Va crd_key 369key length. 370.It Va crd_skip 371The offset in the input buffer where processing should start. 372.It Va crd_len 373How many bytes, after 374.Va crd_skip , 375should be processed. 376.It Va crd_inject 377The 378.Va crd_inject 379field specifies an offset in bytes from the beginning of the buffer. 380For encryption algorithms, this may be where the IV will be inserted 381when encrypting or where the IV may be found for 382decryption (subject to 383.Va crd_flags ) . 384For MAC algorithms, this is where the result of the keyed hash will be 385inserted. 386.It Va crd_flags 387The following flags are defined: 388.Bl -tag -width 3n 389.It Dv CRD_F_ENCRYPT 390For 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. 394For encryption, if this bit is not set the IV used to encrypt the packet 395will be written at the location pointed to by 396.Va crd_inject . 397The IV length is assumed to be equal to the blocksize of the 398encryption algorithm. 399For encryption, if this bit is set, nothing is done. 400For decryption, this flag has no meaning. 401Applications that do special 402.Dq "IV cooking" , 403such as the half-IV mode in 404.Xr ipsec 4 , 405can use this flag to indicate that the IV should not be written on the packet. 406This flag is typically used in conjunction with the 407.Dv CRD_F_IV_EXPLICIT 408flag. 409.It Dv CRD_F_IV_EXPLICIT 410This bit is set when the IV is explicitly 411provided by the consumer in the 412.Va crd_iv 413field. 414Otherwise, for encryption operations the IV is provided for by 415the driver used to perform the operation, whereas for decryption 416operations the offset of the IV is provided by the 417.Va crd_inject 418field. 419This flag is typically used when the IV is calculated 420.Dq "on the fly" 421by the consumer, and does not precede the data (some 422.Xr ipsec 4 423configurations, and the encrypted swap are two such examples). 424.It Dv CRD_F_KEY_EXPLICIT 425For encryption and authentication (MAC) algorithms, this bit is set when the key 426is explicitly provided by the consumer in the 427.Va crd_key 428field for the given operation. 429Otherwise, the key is taken at newsession time from the 430.Va cri_key 431field. 432As calculating the key schedule may take a while, it is recommended that often 433used keys are given their own session. 434.It Dv CRD_F_COMP 435For compression algorithms, this bit is set when compression is required (when 436not set, decompression is performed). 437.El 438.It Va CRD_INI 439This 440.Vt cryptoini 441structure will not be modified by the framework or the device drivers. 442Since this information accompanies every cryptographic 443operation request, drivers may re-initialize state on-demand 444(typically an expensive operation). 445Furthermore, the cryptographic 446framework may re-route requests as a result of full queues or hardware 447failure, as described above. 448.It Va crd_next 449Point to the next descriptor. 450Linked operations are useful in protocols such as 451.Xr ipsec 4 , 452where multiple cryptographic transforms may be applied on the same 453block of data. 454.El 455.El 456.Pp 457.Fn crypto_getreq 458allocates a 459.Vt cryptop 460structure with a linked list of as many 461.Vt cryptodesc 462structures as were specified in the argument passed to it. 463.Pp 464.Fn crypto_freereq 465deallocates a structure 466.Vt cryptop 467and any 468.Vt cryptodesc 469structures linked to it. 470Note that it is the responsibility of the 471callback routine to do the necessary cleanups associated with the 472opaque field in the 473.Vt cryptop 474structure. 475.Pp 476.Fn crypto_kdispatch 477is called to perform a keying operation. 478The various fields in the 479.Vt cryptkop 480structure are: 481.Bl -tag -width ".Va krp_callback" 482.It Va krp_op 483Operation code, such as 484.Dv CRK_MOD_EXP . 485.It Va krp_status 486Return code. 487This 488.Va errno Ns -style 489variable indicates whether lower level reasons 490for operation failure. 491.It Va krp_iparams 492Number if input parameters to the specified operation. 493Note that each operation has a (typically hardwired) number of such parameters. 494.It Va krp_oparams 495Number if output parameters from the specified operation. 496Note that each operation has a (typically hardwired) number of such parameters. 497.It Va krp_kvp 498An array of kernel memory blocks containing the parameters. 499.It Va krp_hid 500Identifier specifying which low-level driver is being used. 501.It Va krp_callback 502Callback called on completion of a keying operation. 503.El 504.Sh DRIVER-SIDE API 505The 506.Fn crypto_get_driverid , 507.Fn crypto_register , 508.Fn crypto_kregister , 509.Fn crypto_unregister , 510.Fn crypto_unblock , 511and 512.Fn crypto_done 513routines are used by drivers that provide support for cryptographic 514primitives to register and unregister with the kernel crypto services 515framework. 516.Pp 517Drivers must first use the 518.Fn crypto_get_driverid 519function to acquire a driver identifier, specifying the 520.Fa flags 521as an argument. 522One of 523.Dv CRYPTOCAP_F_SOFTWARE 524or 525.Dv CRYPTOCAP_F_HARDWARE 526must be specified. 527The 528.Dv CRYPTOCAP_F_SYNC 529may also be specified, and should be specified if the driver does all of 530it's operations synchronously. 531.Pp 532For each algorithm the driver supports, it must then call 533.Fn crypto_register . 534The first two arguments are the driver and algorithm identifiers. 535The next two arguments specify the largest possible operator length (in bits, 536important for public key operations) and flags for this algorithm. 537The last four arguments must be provided in the first call to 538.Fn crypto_register 539and are ignored in all subsequent calls. 540They are pointers to three 541driver-provided functions that the framework may call to establish new 542cryptographic context with the driver, free already established 543context, and ask for a request to be processed (encrypt, decrypt, 544etc.); and an opaque parameter to pass when calling each of these routines. 545.Pp 546.Fn crypto_unregister 547is called by drivers that wish to withdraw support for an algorithm. 548The two arguments are the driver and algorithm identifiers, respectively. 549Typically, drivers for 550PCMCIA 551crypto cards that are being ejected will invoke this routine for all 552algorithms supported by the card. 553.Fn crypto_unregister_all 554will unregister all algorithms registered by a driver 555and the driver will be disabled (no new sessions will be allocated on 556that driver, and any existing sessions will be migrated to other 557drivers). 558The same will be done if all algorithms associated with a driver are 559unregistered one by one. 560After a call to 561.Fn crypto_unregister_all 562there will be no threads in either the newsession or freesession function 563of the driver. 564.Pp 565The calling convention for the three driver-supplied routines are: 566.Pp 567.Bl -item -compact 568.It 569.Ft int 570.Fn \*[lp]*newsession\*[rp] "device_t" "uint32_t *" "struct cryptoini *" ; 571.It 572.Ft int 573.Fn \*[lp]*freesession\*[rp] "device_t" "uint64_t" ; 574.It 575.Ft int 576.Fn \*[lp]*process\*[rp] "device_t" "struct cryptop *" "int" ; 577.It 578.Ft int 579.Fn \*[lp]*kprocess\*[rp] "device_t" "struct cryptkop *" "int" ; 580.El 581.Pp 582On invocation, the first argument to 583all routines is the 584.Fa device_t 585that was provided to 586.Fn crypto_get_driverid . 587The second argument to 588.Fn newsession 589contains the driver identifier obtained via 590.Fn crypto_get_driverid . 591On successful return, it should contain a driver-specific session 592identifier. 593The third argument is identical to that of 594.Fn crypto_newsession . 595.Pp 596The 597.Fn freesession 598routine takes as arguments the opaque data value and the SID 599(which is the concatenation of the 600driver identifier and the driver-specific session identifier). 601It should clear any context associated with the session (clear hardware 602registers, memory, etc.). 603.Pp 604The 605.Fn process 606routine is invoked with a request to perform crypto processing. 607This routine must not block or sleep, but should queue the request and return 608immediately or process the request to completion. 609In case of an unrecoverable error, the error indication must be placed in the 610.Va crp_etype 611field of the 612.Vt cryptop 613structure. 614When the request is completed, or an error is detected, the 615.Fn process 616routine must invoke 617.Fn crypto_done . 618Session migration may be performed, as mentioned previously. 619.Pp 620In case of a temporary resource exhaustion, the 621.Fn process 622routine may return 623.Er ERESTART 624in which case the crypto services will requeue the request, mark the driver 625as 626.Dq blocked , 627and stop submitting requests for processing. 628The driver is then responsible for notifying the crypto services 629when it is again able to process requests through the 630.Fn crypto_unblock 631routine. 632This simple flow control mechanism should only be used for short-lived 633resource exhaustion as it causes operations to be queued in the crypto 634layer. 635Doing so is preferable to returning an error in such cases as 636it can cause network protocols to degrade performance by treating the 637failure much like a lost packet. 638.Pp 639The 640.Fn kprocess 641routine is invoked with a request to perform crypto key processing. 642This routine must not block, but should queue the request and return 643immediately. 644Upon processing the request, the callback routine should be invoked. 645In case of an unrecoverable error, the error indication must be placed in the 646.Va krp_status 647field of the 648.Vt cryptkop 649structure. 650When the request is completed, or an error is detected, the 651.Fn kprocess 652routine should invoked 653.Fn crypto_kdone . 654.Sh RETURN VALUES 655.Fn crypto_register , 656.Fn crypto_kregister , 657.Fn crypto_unregister , 658.Fn crypto_newsession , 659.Fn crypto_freesession , 660and 661.Fn crypto_unblock 662return 0 on success, or an error code on failure. 663.Fn crypto_get_driverid 664returns a non-negative value on error, and \-1 on failure. 665.Fn crypto_getreq 666returns a pointer to a 667.Vt cryptop 668structure and 669.Dv NULL 670on failure. 671.Fn crypto_dispatch 672returns 673.Er EINVAL 674if its argument or the callback function was 675.Dv NULL , 676and 0 otherwise. 677The callback is provided with an error code in case of failure, in the 678.Va crp_etype 679field. 680.Sh FILES 681.Bl -tag -width ".Pa sys/opencrypto/crypto.c" 682.It Pa sys/opencrypto/crypto.c 683most of the framework code 684.El 685.Sh SEE ALSO 686.Xr crypto 4 , 687.Xr ipsec 4 , 688.Xr crypto 7 , 689.Xr malloc 9 , 690.Xr sleep 9 691.Sh HISTORY 692The cryptographic framework first appeared in 693.Ox 2.7 694and was written by 695.An Angelos D. Keromytis Aq Mt angelos@openbsd.org . 696.Sh BUGS 697The framework currently assumes that all the algorithms in a 698.Fn crypto_newsession 699operation must be available by the same driver. 700If that is not the case, session initialization will fail. 701.Pp 702The framework also needs a mechanism for determining which driver is 703best for a specific set of algorithms associated with a session. 704Some type of benchmarking is in order here. 705.Pp 706Multiple instances of the same algorithm in the same session are not 707supported. 708Note that 3DES is considered one algorithm (and not three 709instances of DES). 710Thus, 3DES and DES could be mixed in the same request. 711