.\" $NetBSD: crypto.4,v 1.25.8.1 2019/09/02 16:39:20 martin Exp $ .\" .\" Copyright (c) 2008 The NetBSD Foundation, Inc. .\" All rights reserved. .\" .\" This code is derived from software contributed to The NetBSD Foundation .\" by Coyote Point Systems, Inc. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS .\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED .\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .\" .\" .\" Copyright (c) 2004 .\" Jonathan Stone . All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY Jonathan Stone AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL Jonathan Stone OR THE VOICES IN HIS HEAD .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF .\" THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd January 27, 2014 .Dt CRYPTO 4 .Os .Sh NAME .Nm crypto , .Nm swcrypto .Nd user-mode access to hardware-accelerated cryptography .Sh SYNOPSIS .Cd "hifn* at pci? dev ? function ?" .Cd "ubsec* at pci? dev ? function ?" .Pp .Cd pseudo-device crypto .Cd pseudo-device swcrypto .Pp .In sys/ioctl.h .In sys/time.h .In crypto/cryptodev.h .Sh DESCRIPTION The .Nm driver gives user-mode applications access to hardware-accelerated cryptographic transforms, as implemented by the .Xr opencrypto 9 in-kernel interface. .Pp The .Cm swcrypto driver is a software-only implementation of the .Xr opencrypto 9 interface, and must be included to use the interface without hardware acceleration. .Pp The .Pa /dev/crypto special device provides an .Xr ioctl 2 based interface. User-mode applications should open the special device, then issue .Xr ioctl 2 calls on the descriptor. User-mode access to .Pa /dev/crypto is generally controlled by three .Xr sysctl 8 variables, .Ic kern.usercrypto , .Ic kern.userasymcrypto , and .Ic kern.cryptodevallowsoft . See .Xr sysctl 7 for additional details. .Pp The .Nm device provides two distinct modes of operation: one mode for symmetric-keyed cryptographic requests, and a second mode for both asymmetric-key (public-key/private-key) requests, and for modular arithmetic (for Diffie-Hellman key exchange and other cryptographic protocols). The two modes are described separately below. .Sh THEORY OF OPERATION Regardless of whether symmetric-key or asymmetric-key operations are to be performed, use of the device requires a basic series of steps: .Pp .Bl -enum .It Open a file descriptor for the device. See .Xr open 2 . .It If any symmetric operation will be performed, create one session, with .Dv CIOCGSESSION , or multiple sessions, with .Dv CIOCNGSESSION . Most applications will require at least one symmetric session. Since cipher and MAC keys are tied to sessions, many applications will require more. Asymmetric operations do not use sessions. .It Submit requests, synchronously with .Dv CIOCCRYPT (symmetric) or .Dv CIOCKEY (asymmetric) or asynchronously with .Dv CIOCNCRYPTM (symmetric) or .Dv CIOCNFKEYM (asymmetric). The asynchronous interface allows multiple requests to be submitted in one call if the user so desires. .It If the asynchronous interface is used, wait for results with .Xr select 2 or .Xr poll 2 , then collect them with .Dv CIOCNCRYPTRET (a particular request) or .Dv CIOCNCRYPTRETM (multiple requests). .It Destroy one session with .Dv CIOCFSESSION or many at once with .Dv CIOCNFSESSION . .It Close the device with .Xr close 2 . .El .Sh SYMMETRIC-KEY OPERATION The symmetric-key operation mode provides a context-based API to traditional symmetric-key encryption (or privacy) algorithms, or to keyed and unkeyed one-way hash (HMAC and MAC) algorithms. The symmetric-key mode also permits fused operation, where the hardware performs both a privacy algorithm and an integrity-check algorithm in a single pass over the data: either a fused encrypt/HMAC-generate operation, or a fused HMAC-verify/decrypt operation. .Pp To use symmetric mode, you must first create a session specifying the algorithm(s) and key(s) to use; then issue encrypt or decrypt requests against the session. .Ss Symmetric-key privacy algorithms Contingent upon device drivers for installed cryptographic hardware registering with .Xr opencrypto 9 , as providers of a given algorithm, some or all of the following symmetric-key privacy algorithms may be available: .Pp .Bl -tag -compact -width CRYPTO_RIPEMD160_HMAC -offset indent .It CRYPTO_DES_CBC .It CRYPTO_3DES_CBC .It CRYPTO_BLF_CBC .It CRYPTO_CAST_CBC .It CRYPTO_SKIPJACK_CBC .It CRYPTO_AES_CBC .It CRYPTO_ARC4 .El .Ss Integrity-check operations Contingent upon hardware support, some or all of the following keyed one-way hash algorithms may be available: .Pp .Bl -tag -compact -width CRYPTO_RIPEMD160_HMAC -offset indent .It CRYPTO_RIPEMD160_HMAC .It CRYPTO_MD5_KPDK .It CRYPTO_SHA1_KPDK .It CRYPTO_MD5_HMAC .It CRYPTO_SHA1_HMAC .It CRYPTO_SHA2_256_HMAC .It CRYPTO_SHA2_384_HMAC .It CRYPTO_SHA2_512_HMAC .It CRYPTO_MD5 .It CRYPTO_SHA1 .El .Pp The .Em CRYPTO_MD5 and .Em CRYPTO_SHA1 algorithms are actually unkeyed, but should be requested as symmetric-key hash algorithms with a zero-length key. .Ss IOCTL Request Descriptions .\" .Bl -tag -width CIOCKEY .\" .It Dv CRIOGET Fa int *fd This operation is deprecated and will be removed after .Nx 5.0 . It clones the fd argument to .Xr ioctl 2 , yielding a new file descriptor for the creation of sessions. Because the device now clones on open, this operation is unnecessary. .\" .It Dv CIOCGSESSION Fa struct session_op *sessp .Bd -literal struct session_op { u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */ u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */ u_int32_t keylen; /* cipher key */ void * key; int mackeylen; /* mac key */ void * mackey; u_int32_t ses; /* returns: ses # */ }; .Ed Create a new cryptographic session on a file descriptor for the device; that is, a persistent object specific to the chosen privacy algorithm, integrity algorithm, and keys specified in .Fa sessp . The special value 0 for either privacy or integrity is reserved to indicate that the indicated operation (privacy or integrity) is not desired for this session. .Pp Multiple sessions may be bound to a single file descriptor. The session ID returned in .Fa sessp->ses is supplied as a required field in the symmetric-operation structure .Fa crypt_op for future encryption or hashing requests. .Pp This implementation will never return a session ID of 0 for a successful creation of a session, which is a .Nx extension. .Pp For non-zero symmetric-key privacy algorithms, the privacy algorithm must be specified in .Fa sessp->cipher , the key length in .Fa sessp->keylen , and the key value in the octets addressed by .Fa sessp->key . .Pp For keyed one-way hash algorithms, the one-way hash must be specified in .Fa sessp->mac , the key length in .Fa sessp->mackey , and the key value in the octets addressed by .Fa sessp->mackeylen . .\" .Pp Support for a specific combination of fused privacy and integrity-check algorithms depends on whether the underlying hardware supports that combination. Not all combinations are supported by all hardware, even if the hardware supports each operation as a stand-alone non-fused operation. .It Dv CIOCNGSESSION Fa struct crypt_sgop *sgop .Bd -literal struct crypt_sgop { size_t count; /* how many */ struct session_n_op * sessions; /* where to get them */ }; struct session_n_op { u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */ u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */ u_int32_t keylen; /* cipher key */ void * key; u_int32_t mackeylen; /* mac key */ void * mackey; u_int32_t ses; /* returns: session # */ int status; }; .Ed Create one or more sessions. Takes a counted array of .Fa session_n_op structures in .Fa sgop . For each requested session (array element n), the session number is returned in .Fa sgop->sessions[n].ses and the status for that session creation in .Fa sgop->sessions[n].status . .\" .It Dv CIOCCRYPT Fa struct crypt_op *cr_op .Bd -literal struct crypt_op { u_int32_t ses; u_int16_t op; /* e.g. COP_ENCRYPT */ u_int16_t flags; u_int len; void * src, *dst; void * mac; /* must be large enough for result */ void * iv; }; .Ed Request a symmetric-key (or hash) operation. The file descriptor argument to .Xr ioctl 2 must have been bound to a valid session. To encrypt, set .Fa cr_op->op to .Dv COP_ENCRYPT . To decrypt, set .Fa cr_op->op to .Dv COP_DECRYPT . The field .Fa cr_op->len supplies the length of the input buffer; the fields .Fa cr_op->src , .Fa cr_op->dst , .Fa cr_op->mac , .Fa cr_op->iv supply the addresses of the input buffer, output buffer, one-way hash, and initialization vector, respectively. .It Dv CIOCNCRYPTM Fa struct crypt_mop *cr_mop .Bd -literal struct crypt_mop { size_t count; /* how many */ struct crypt_n_op * reqs; /* where to get them */ }; struct crypt_n_op { u_int32_t ses; u_int16_t op; /* e.g. COP_ENCRYPT */ u_int16_t flags; u_int len; u_int32_t reqid; /* request id */ int status; /* accepted or not */ void *opaque; /* opaque pointer ret to user */ u_int32_t keylen; /* cipher key - optional */ void * key; u_int32_t mackeylen; /* mac key - optional */ void * mackey; void * src, * dst; void * mac; void * iv; }; .Ed This is the asynchronous version of CIOCCRYPT, which allows multiple symmetric-key (or hash) operations to be started (see CIOCRYPT above for the details for each operation). .Pp The .Fa cr_mop->count field specifies the number of operations provided in the cr_mop->reqs array. .Pp Each operation is assigned a unique request id returned in the .Fa cr_mop->reqs[n].reqid field. .Pp Each operation can accept an opaque value from the user to be passed back to the user when the operation completes (e.g., to track context for the request). The opaque field is .Fa cr_mop->reqs[n].opaque . .Pp If a problem occurs with starting any of the operations then that operation's .Fa cr_mop->reqs[n].status field is filled with the error code. The failure of an operation does not prevent the other operations from being started. .Pp The .Xr select 2 or .Xr poll 2 functions must be used on the device file descriptor to detect that some operation has completed; results are then retrieved with .Dv CIOCNCRYPTRETM . .Pp The .Fa key and .Fa mackey fields of the operation structure are currently unused. They are intended for use to immediately rekey an existing session before processing a new request. .It Dv CIOCFSESSION Fa u_int32_t *ses_id Destroys the /dev/crypto session associated with the file-descriptor argument. .It Dv CIOCNFSESSION Fa struct crypt_sfop *sfop .Bd -literal struct crypt_sfop { size_t count; u_int32_t *sesid; }; .Ed Destroys the .Fa sfop->count sessions specified by the .Fa sfop array of session identifiers. .El .\" .Sh ASYMMETRIC-KEY OPERATION .Ss Asymmetric-key algorithms Contingent upon hardware support, the following asymmetric (public-key/private-key; or key-exchange subroutine) operations may also be available: .Pp .Bl -column "CRK_DH_COMPUTE_KEY" "Input parameter" "Output parameter" -offset indent -compact .It Em "Algorithm" Ta "Input parameter" Ta "Output parameter" .It Em " " Ta "Count" Ta "Count" .It Dv CRK_MOD_EXP Ta 3 Ta 1 .It Dv CRK_MOD_EXP_CRT Ta 6 Ta 1 .It Dv CRK_MOD_ADD Ta 3 Ta 1 .It Dv CRK_MOD_ADDINV Ta 2 Ta 1 .It Dv CRK_MOD_SUB Ta 3 Ta 1 .It Dv CRK_MOD_MULT Ta 3 Ta 1 .It Dv CRK_MOD_MULTINV Ta 2 Ta 1 .It Dv CRK_MOD Ta 2 Ta 1 .It Dv CRK_DSA_SIGN Ta 5 Ta 2 .It Dv CRK_DSA_VERIFY Ta 7 Ta 0 .It Dv CRK_DH_COMPUTE_KEY Ta 3 Ta 1 .El .Pp See below for discussion of the input and output parameter counts. .Ss Asymmetric-key commands .Bl -tag -width CIOCKEY .It Dv CIOCASYMFEAT Fa int *feature_mask Returns a bitmask of supported asymmetric-key operations. Each of the above-listed asymmetric operations is present if and only if the bit position numbered by the code for that operation is set. For example, .Dv CRK_MOD_EXP is available if and only if the bit .Pq 1 << Dv CRK_MOD_EXP is set. .It Dv CIOCKEY Fa struct crypt_kop *kop .Bd -literal struct crypt_kop { u_int crk_op; /* e.g. CRK_MOD_EXP */ u_int crk_status; /* return status */ u_short crk_iparams; /* # of input params */ u_short crk_oparams; /* # of output params */ u_int crk_pad1; struct crparam crk_param[CRK_MAXPARAM]; }; /* Bignum parameter, in packed bytes. */ struct crparam { void * crp_p; u_int crp_nbits; }; .Ed Performs an asymmetric-key operation from the list above. The specific operation is supplied in .Fa kop->crk_op ; final status for the operation is returned in .Fa kop->crk_status . The number of input arguments and the number of output arguments is specified in .Fa kop->crk_iparams and .Fa kop->crk_iparams , respectively. The field .Fa crk_param[] must be filled in with exactly .Fa kop->crk_iparams + kop->crk_oparams arguments, each encoded as a .Fa struct crparam (address, bitlength) pair. .Pp The semantics of these arguments are currently undocumented. .It Dv CIOCNFKEYM Fa struct crypt_mkop *mkop .Bd -literal struct crypt_mkop { size_t count; /* how many */ struct crypt_n_op * reqs; /* where to get them */ }; struct crypt_n_kop { u_int crk_op; /* e.g. CRK_MOD_EXP */ u_int crk_status; /* accepted or not */ u_short crk_iparams; /* # of input params */ u_short crk_oparams; /* # of output params */ u_int32_t crk_reqid; /* request id */ struct crparam crk_param[CRK_MAXPARAM]; void *crk_opaque; /* opaque pointer ret to user */ }; .Ed This is the asynchronous version of .Dv CIOCKEY , which starts one or more key operations. See .Dv CIOCNCRYPTM above and .Dv CIOCNCRYPTRETM below for descriptions of the .Fa mkop>count , .Fa mkop>reqs , .Fa mkop>reqs[n].crk_reqid , .Fa mkop>reqs[n].crk_status , and .Fa mkop>reqs[n].crk_opaque fields of the argument structure, and result retrieval. .El .Ss Asynchronous status commands When requests are submitted with the .Dv CIOCNCRYPTM or .Dv CIOCNFKEYM commands, result retrieval is asynchronous (the submit ioctls return immediately). Use the .Xr select 2 or .Xr poll 2 functions to determine when the file descriptor has completed operations ready to be retrieved. .Bl -tag -width CIOCKEY .It Dv CIOCNCRYPTRET Fa struct crypt_result *cres .Bd -literal struct crypt_result { u_int32_t reqid; /* request ID */ u_int32_t status; /* 0 if successful */ void * opaque; /* pointer from user */ }; .Ed Check for the status of the request specified by .Fa cres->reqid . This requires a linear search through all completed requests and should be used with extreme care if the number of requests pending on this file descriptor may be large. .Pp The .Fa cres->status field is set as follows: .Bl -tag -width EINPROGRESS .It 0 The request has completed, and its results have been copied out to the original .Fa crypt_n_op or .Fa crypt_n_kop structure used to start the request. The copyout occurs during this ioctl, so the calling process must be the process that started the request. .It EINPROGRESS The request has not yet completed. .It EINVAL The request was not found. .El .Pp Other values indicate a problem during the processing of the request. .It Dv CIOCNCRYPTRETM Fa struct cryptret_t *cret .Bd -literal struct cryptret { size_t count; /* space for how many */ struct crypt_result * results; /* where to put them */ }; .Ed Retrieve a number of completed requests. This ioctl accepts a count and an array (each array element is a .Fa crypt_result_t structure as used by .Dv CIOCNCRYPTRET above) and fills the array with up to .Fa cret->count results of completed requests. .Pp This ioctl fills in the .Fa cret->results[n].reqid field , so that the request which has completed may be identified by the application. Note that the results may include requests submitted both as symmetric and asymmetric operations. .El .Sh SEE ALSO .Xr hifn 4 , .Xr ubsec 4 , .Xr opencrypto 9 .Sh HISTORY The .Nm driver is derived from a version which appeared in .Fx 4.8 , which in turn is based on code which appeared in .Ox 3.2 . .Pp The "new API" for asynchronous operation with multiple basic operations per system call (the "N" ioctl variants) was contributed by Coyote Point Systems, Inc. and first appeared in .Nx 5.0 . .Sh BUGS Error checking and reporting is weak. .Pp The values specified for symmetric-key key sizes to .Dv CIOCGSESSION must exactly match the values expected by .Xr opencrypto 9 . The output buffer and MAC buffers supplied to .Dv CIOCCRYPT must follow whether privacy or integrity algorithms were specified for session: if you request a .No non- Ns Dv NULL algorithm, you must supply a suitably-sized buffer. .Pp The scheme for passing arguments for asymmetric requests is baroque. .Pp The naming inconsistency between .Dv CRIOGET and the various .Dv CIOC Ns \&* names is an unfortunate historical artifact.