1.\" Copyright (c) 2020, Chelsio Inc 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions are met: 5.\" 6.\" 1. Redistributions of source code must retain the above copyright notice, 7.\" this list of conditions and the following disclaimer. 8.\" 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" 3. Neither the name of the Chelsio Inc nor the names of its 14.\" contributors may be used to endorse or promote products derived from 15.\" this software without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27.\" POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" * Other names and brands may be claimed as the property of others. 30.\" 31.\" $FreeBSD$ 32.\" 33.Dd February 11, 2022 34.Dt CRYPTO_BUFFER 9 35.Os 36.Sh NAME 37.Nm crypto_buffer 38.Nd symmetric cryptographic request buffers 39.Sh SYNOPSIS 40.In opencrypto/cryptodev.h 41.Ft int 42.Fo crypto_apply 43.Fa "struct cryptop *crp" 44.Fa "int off" 45.Fa "int len" 46.Fa "int (*f)(void *, void *, u_int)" 47.Fa "void *arg" 48.Fc 49.Ft int 50.Fo crypto_apply_buf 51.Fa "struct crypto_buffer *cb" 52.Fa "int off" 53.Fa "int len" 54.Fa "int (*f)(void *, void *, u_int)" 55.Fa "void *arg" 56.Fc 57.Ft void * 58.Fo crypto_buffer_contiguous_subsegment 59.Fa "struct crypto_buffer *cb" 60.Fa "size_t skip" 61.Fa "size_t len" 62.Fc 63.Ft size_t 64.Fn crypto_buffer_len "struct crypto_buffer *cb" 65.Ft void * 66.Fo crypto_contiguous_subsegment 67.Fa "struct cryptop *crp" 68.Fa "size_t skip" 69.Fa "size_t len" 70.Fc 71.Ft void 72.Fo crypto_cursor_init 73.Fa "struct crypto_buffer_cursor *cc" 74.Fa "const struct crypto_buffer *cb" 75.Fc 76.Ft void 77.Fn crypto_cursor_advance "struct crypto_buffer_cursor *cc" "size_t amount" 78.Ft void 79.Fo crypto_cursor_copyback 80.Fa "struct crypto_buffer_cursor *cc" 81.Fa "int size" 82.Fa "const void *src" 83.Fc 84.Ft void 85.Fo crypto_cursor_copydata 86.Fa "struct crypto_buffer_cursor *cc" 87.Fa "int size" 88.Fa "void *dst" 89.Fc 90.Ft void 91.Fo crypto_cursor_copydata_noadv 92.Fa "struct crypto_buffer_cursor *cc" 93.Fa "int size" 94.Fa "void *dst" 95.Fc 96.Ft void * 97.Fn crypto_cursor_segment "struct crypto_buffer_cursor *cc" "size_t *len" 98.Ft void 99.Fo crypto_cursor_copy 100.Fa "const struct crypto_buffer_cursor *fromc" 101.Fa "struct crypto_buffer_cursor *toc" 102.Fc 103.Ft bool 104.Fn CRYPTO_HAS_OUTPUT_BUFFER "struct cryptop *crp" 105.Sh DESCRIPTION 106Symmetric cryptographic requests use data buffers to describe the data to 107be modified. 108Requests can either specify a single data buffer whose contents are modified 109in place, 110or requests may specify separate data buffers for input and output. 111.Vt struct crypto_buffer 112provides an abstraction that permits cryptographic requests to operate on 113different types of buffers. 114.Vt struct crypto_cursor 115allows cryptographic drivers to iterate over a data buffer. 116.Pp 117.Fn CRYPTO_HAS_OUTPUT_BUFFER 118returns true if 119.Fa crp 120uses separate buffers for input and output and false if 121.Fa crp 122uses a single buffer. 123.Pp 124.Fn crypto_buffer_len 125returns the length of data buffer 126.Fa cb 127in bytes. 128.Pp 129.Fn crypto_apply_buf 130invokes a caller-supplied function 131to a region of the data buffer 132.Fa cb . 133The function 134.Fa f 135is called one or more times. 136For each invocation, 137the first argument to 138.Fa f 139is the value of 140.Fa arg 141passed to 142.Fn crypto_apply_buf . 143The second and third arguments to 144.Fa f 145are a pointer and length to a segment of the buffer mapped into the kernel. 146The function is called enough times to cover the 147.Fa len 148bytes of the data buffer which starts at an offset 149.Fa off . 150If any invocation of 151.Fa f 152returns a non-zero value, 153.Fn crypto_apply_buf 154immediately returns that value without invoking 155.Fa f 156on any remaining segments of the region, 157otherwise 158.Fn crypto_apply_buf 159returns the value from the final call to 160.Fa f . 161.Fn crypto_apply 162invokes the callback 163.Fa f 164on a region of the input data buffer for 165.Fa crp . 166.Pp 167.Fn crypto_buffer_contiguous_subsegment 168attempts to locate a single, virtually-contiguous segment of the data buffer 169.Fa cb . 170The segment must be 171.Fa len 172bytes long and start at an offset of 173.Fa skip 174bytes. 175If a segment is found, 176a pointer to the start of the segment is returned. 177Otherwise, 178.Dv NULL 179is returned. 180.Fn crypto_contiguous_subsegment 181attempts to locate a single, virtually-contiguous segment in the input data 182buffer for 183.Fa crp . 184.Ss Data Buffers 185Data buffers are described by an instance of 186.Vt struct crypto buffer . 187The 188.Fa cb_type 189member contains the type of the data buffer. 190The following types are supported: 191.Bl -tag -width " CRYPTO_BUF_CONTIG" 192.It Dv CRYPTO_BUF_NONE 193An invalid buffer. 194Used to mark the output buffer when a crypto request uses a single data buffer. 195.It Dv CRYPTO_BUF_CONTIG 196An array of bytes mapped into the kernel's address space. 197.It Dv CRYPTO_BUF_UIO 198A scatter/gather list of kernel buffers as described in 199.Xr uio 9 . 200.It Dv CRYPTO_BUF_MBUF 201A chain of network memory buffers as described in 202.Xr mbuf 9 . 203.It Dv CRYPTO_BUF_SINGLE_MBUF 204A single network memory buffer as described in 205.Xr mbuf 9 . 206.It Dv CRYPTO_BUF_VMPAGE 207A scatter/gather list of 208.Vt vm_page_t 209structures describing pages in the kernel's address space. 210This buffer type is only available if 211.Dv CRYPTO_HAS_VMPAGE 212is true. 213.El 214.Pp 215The structure also contains the following type-specific fields: 216.Bl -tag -width " cb_vm_page_offset" 217.It Fa cb_buf 218A pointer to the start of a 219.Dv CRYPTO_BUF_CONTIG 220data buffer. 221.It Fa cb_buf_len 222The length of a 223.Dv CRYPTO_BUF_CONTIG 224data buffer 225.It Fa cb_mbuf 226A pointer to a 227.Vt struct mbuf 228for 229.Dv CRYPTO_BUF_MBUF 230and 231.Dv CRYPTO_BUF_SINGLE_MBUF . 232.It Fa cb_uio 233A pointer to a 234.Vt struct uio 235for 236.Dv CRYPTO_BUF_UIO . 237.It Fa cb_vm_page 238A pointer to an array of 239.Vt struct vm_page 240for 241.Dv CRYPTO_BUF_VMPAGE . 242.It Fa cb_vm_page_len 243The total amount of data included in the 244.Fa cb_vm_page 245array, in bytes. 246.It Fa cb_vm_page_offset 247Offset in bytes in the first page of 248.Fa cb_vm_page 249where valid data begins. 250.El 251.Ss Cursors 252Cursors provide a mechanism for iterating over a data buffer. 253They are primarily intended for use in software drivers which access data 254buffers via virtual addresses. 255.Pp 256.Fn crypto_cursor_init 257initializes the cursor 258.Fa cc 259to reference the start of the data buffer 260.Fa cb . 261.Pp 262.Fn crypto_cursor_advance 263advances the cursor 264.Fa amount 265bytes forward in the data buffer. 266.Pp 267.Fn crypto_cursor_copyback 268copies 269.Fa size 270bytes from the local buffer pointed to by 271.Fa src 272into the data buffer associated with 273.Fa cc . 274The bytes are written to the current position of 275.Fa cc , 276and the cursor is then advanced by 277.Fa size 278bytes. 279.Pp 280.Fn crypto_cursor_copydata 281copies 282.Fa size 283bytes out of the data buffer associated with 284.Fa cc 285into a local buffer pointed to by 286.Fa dst . 287The bytes are read from the current position of 288.Fa cc , 289and the cursor is then advanced by 290.Fa size 291bytes. 292.Pp 293.Fn crypto_cursor_copydata_noadv 294is similar to 295.Fn crypto_cursor_copydata 296except that it does not change the current position of 297.Fa cc . 298.Pp 299.Fn crypto_cursor_segment 300returns the start of the virtually-contiguous segment at the current position of 301.Fa cc . 302The length of the segment is stored in 303.Fa len . 304.Sh RETURN VALUES 305.Fn crypto_apply 306and 307.Fn crypto_apply_buf 308return the return value from the caller-supplied callback function. 309.Pp 310.Fn crypto_buffer_contiguous_subsegment , 311.Fn crypto_contiguous_subsegment , 312and 313.Fn crypto_cursor_segment 314return a pointer to a contiguous segment or 315.Dv NULL . 316.Pp 317.Fn crypto_buffer_len 318returns the length of a buffer in bytes. 319.Pp 320.Fn crypto_cursor_seglen 321returns the length in bytes of a contiguous segment. 322.Pp 323.Fn crypto_cursor_copy 324makes a deep copy of the cursor 325.Fa fromc . 326The two copies do not share any state and can thus be used 327independently. 328.Pp 329.Fn CRYPTO_HAS_OUTPUT_BUFFER 330returns true if the request uses a separate output buffer. 331.Sh SEE ALSO 332.Xr ipsec 4 , 333.Xr crypto 7 , 334.Xr bus_dma 9 , 335.Xr crypto 9 , 336.Xr crypto_driver 9 , 337.Xr crypto_request 9 , 338.Xr crypto_session 9 , 339.Xr mbuf 9 , 340.Xr uio 9 341.Sh HISTORY 342The 343.Nm 344functions first appeared in 345.Fx 13 . 346.Sh AUTHORS 347The 348.Nm 349functions and this manual page were written by 350.An John Baldwin Aq Mt jhb@FreeBSD.org . 351