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e6f6d0c9bc
crypto(9) functions can now be used on buffers composed of an array of vm_page_t structures, such as those stored in an unmapped struct bio. It requires the running to kernel to support the direct memory map, so not all architectures can use it. Reviewed by: markj, kib, jhb, mjg, mat, bcr (manpages) MFC after: 1 week Sponsored by: Axcient Differential Revision: https://reviews.freebsd.org/D25671
327 lines
8.3 KiB
Groff
327 lines
8.3 KiB
Groff
.\" Copyright (c) 2020, Chelsio Inc
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright notice,
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.\" this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" 3. Neither the name of the Chelsio Inc nor the names of its
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.\" contributors may be used to endorse or promote products derived from
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.\" this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" * Other names and brands may be claimed as the property of others.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 12, 2020
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.Dt CRYPTO_BUFFER 9
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.Os
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.Sh NAME
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.Nm crypto_buffer
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.Nd symmetric cryptographic request buffers
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.Sh SYNOPSIS
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.In opencrypto/cryptodev.h
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.Ft int
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.Fo crypto_apply
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.Fa "struct cryptop *crp"
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.Fa "int off"
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.Fa "int len"
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.Fa "int (*f)(void *, void *, u_int)"
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.Fa "void *arg"
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.Fc
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.Ft int
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.Fo crypto_apply_buf
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.Fa "struct crypto_buffer *cb"
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.Fa "int off"
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.Fa "int len"
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.Fa "int (*f)(void *, void *, u_int)"
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.Fa "void *arg"
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.Fc
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.Ft void *
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.Fo crypto_buffer_contiguous_subsegment
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.Fa "struct crypto_buffer *cb"
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.Fa "size_t skip"
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.Fa "size_t len"
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.Fc
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.Ft size_t
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.Fn crypto_buffer_len "struct crypto_buffer *cb"
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.Ft void *
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.Fo crypto_contiguous_subsegment
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.Fa "struct cryptop *crp"
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.Fa "size_t skip"
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.Fa "size_t len"
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.Fc
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.Ft void
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.Fo crypto_cursor_init
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.Fa "struct crypto_buffer_cursor *cc"
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.Fa "const struct crypto_buffer *cb"
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.Fc
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.Ft void
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.Fn crypto_cursor_advance "struct crypto_buffer_cursor *cc" "size_t amount"
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.Ft void
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.Fo crypto_cursor_copyback
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.Fa "struct crypto_buffer_cursor *cc"
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.Fa "int size"
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.Fa "const void *src"
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.Fc
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.Ft void
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.Fo crypto_cursor_copydata
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.Fa "struct crypto_buffer_cursor *cc"
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.Fa "int size"
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.Fa "void *dst"
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.Fc
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.Ft void
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.Fo crypto_cursor_copydata_noadv
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.Fa "struct crypto_buffer_cursor *cc"
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.Fa "int size"
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.Fa "void *dst"
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.Fc
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.Ft void *
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.Fn crypto_cursor_segbase "struct crypto_buffer_cursor *cc"
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.Ft size_t
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.Fn crypto_cursor_seglen "struct crypto_buffer_cursor *cc"
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.Ft bool
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.Fn CRYPTO_HAS_OUTPUT_BUFFER "struct cryptop *crp"
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.Sh DESCRIPTION
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Symmetric cryptographic requests use data buffers to describe the data to
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be modified.
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Requests can either specify a single data buffer whose contents are modified
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in place,
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or requests may specify separate data buffers for input and output.
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.Vt struct crypto_buffer
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provides an abstraction that permits cryptographic requests to operate on
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different types of buffers.
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.Vt struct crypto_cursor
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allows cryptographic drivers to iterate over a data buffer.
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.Pp
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.Fn CRYPTO_HAS_OUTPUT_BUFFER
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returns true if
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.Fa crp
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uses separate buffers for input and output and false if
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.Fa crp
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uses a single buffer.
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.Pp
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.Fn crypto_buffer_len
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returns the length of data buffer
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.Fa cb
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in bytes.
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.Pp
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.Fn crypto_apply_buf
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invokes a caller-supplied function
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to a region of the data buffer
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.Fa cb .
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The function
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.Fa f
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is called one or more times.
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For each invocation,
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the first argument to
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.Fa f
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is the value of
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.Fa arg
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passed to
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.Fn crypto_apply_buf .
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The second and third arguments to
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.Fa f
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are a pointer and length to a segment of the buffer mapped into the kernel.
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The function is called enough times to cover the
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.Fa len
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bytes of the data buffer which starts at an offset
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.Fa off .
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If any invocation of
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.Fa f
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returns a non-zero value,
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.Fn crypto_apply_buf
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immediately returns that value without invoking
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.Fa f
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on any remaining segments of the region,
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otherwise
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.Fn crypto_apply_buf
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returns the value from the final call to
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.Fa f .
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.Fn crypto_apply
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invokes the callback
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.Fa f
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on a region of the input data buffer for
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.Fa crp .
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.Pp
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.Fn crypto_buffer_contiguous_subsegment
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attempts to locate a single, virtually-contiguous segment of the data buffer
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.Fa cb .
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The segment must be
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.Fa len
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bytes long and start at an offset of
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.Fa skip
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bytes.
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If a segment is found,
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a pointer to the start of the segment is returned.
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Otherwise,
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.Dv NULL
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is returned.
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.Fn crypto_contiguous_subsegment
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attempts to locate a single, virtually-contiguous segment in the input data
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buffer for
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.Fa crp .
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.Ss Data Buffers
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Data buffers are described by an instance of
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.Vt struct crypto buffer .
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The
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.Fa cb_type
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member contains the type of the data buffer.
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The following types are supported:
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.Bl -tag -width " CRYPTO_BUF_CONTIG"
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.It Dv CRYPTO_BUF_NONE
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An invalid buffer.
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Used to mark the output buffer when a crypto request uses a single data buffer.
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.It Dv CRYPTO_BUF_CONTIG
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An array of bytes mapped into the kernel's address space.
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.It Dv CRYPTO_BUF_UIO
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A scatter/gather list of kernel buffers as described in
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.Xr uio 9 .
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.It Dv CRYPTO_BUF_MBUF
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A network memory buffer as described in
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.Xr mbuf 9 .
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.It Dv CRYPTO_BUF_VMPAGE
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A scatter/gather list of
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.Vt vm_page_t
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structures describing pages in the kernel's address space.
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This buffer type is only available if
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.Dv CRYPTO_HAS_VMPAGE
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is true.
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.El
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.Pp
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The structure also contains the following type-specific fields:
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.Bl -tag -width " cb_vm_page_offset"
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.It Fa cb_buf
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A pointer to the start of a
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.Dv CRYPTO_BUF_CONTIG
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data buffer.
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.It Fa cb_buf_len
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The length of a
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.Dv CRYPTO_BUF_CONTIG
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data buffer
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.It Fa cb_mbuf
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A pointer to a
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.Vt struct mbuf
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for
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.Dv CRYPTO_BUF_MBUF .
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.It Fa cb_uio
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A pointer to a
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.Vt struct uio
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for
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.Dv CRYPTO_BUF_UIO .
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.It Fa cb_vm_page
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A pointer to an array of
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.Vt struct vm_page
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for
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.Dv CRYPTO_BUF_VMPAGE .
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.It Fa cb_vm_page_len
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The total amount of data included in the
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.Fa cb_vm_page
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array, in bytes.
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.It Fa cb_vm_page_offset
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Offset in bytes in the first page of
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.Fa cb_vm_page
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where valid data begins.
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.El
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.Ss Cursors
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Cursors provide a mechanism for iterating over a data buffer.
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They are primarily intended for use in software drivers which access data
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buffers via virtual addresses.
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.Pp
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.Fn crypto_cursor_init
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initializes the cursor
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.Fa cc
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to reference the start of the data buffer
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.Fa cb .
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.Pp
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.Fn crypto_cursor_advance
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advances the cursor
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.Fa amount
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bytes forward in the data buffer.
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.Pp
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.Fn crypto_cursor_copyback
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copies
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.Fa size
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bytes from the local buffer pointed to by
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.Fa src
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into the data buffer associated with
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.Fa cc .
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The bytes are written to the current position of
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.Fa cc ,
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and the cursor is then advanced by
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.Fa size
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bytes.
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.Pp
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.Fn crypto_cursor_copydata
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copies
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.Fa size
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bytes out of the data buffer associated with
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.Fa cc
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into a local buffer pointed to by
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.Fa dst .
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The bytes are read from the current position of
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.Fa cc ,
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and the cursor is then advanced by
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.Fa size
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bytes.
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.Pp
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.Fn crypto_cursor_copydata_noadv
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is similar to
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.Fn crypto_cursor_copydata
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except that it does not change the current position of
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.Fa cc .
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.Pp
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.Fn crypto_cursor_segbase
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and
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.Fn crypto_cursor_seglen
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return the start and length, respectively,
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of the virtually-contiguous segment at the current position of
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.Fa cc .
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.Sh RETURN VALUES
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.Fn crypto_apply
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and
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.Fn crypto_apply_buf
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return the return value from the caller-supplied callback function.
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.Pp
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.Fn crypto_buffer_contiguous_subsegment ,
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.Fn crypto_contiguous_subsegment ,
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and
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.Fn crypto_cursor_segbase ,
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return a pointer to a contiguous segment or
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.Dv NULL .
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.Pp
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.Fn crypto_buffer_len
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returns the length of a buffer in bytes.
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.Pp
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.Fn crypto_cursor_seglen
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returns the length in bytes of a contiguous segment.
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.Pp
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.Fn CRYPTO_HAS_OUTPUT_BUFFER
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returns true if the request uses a separate output buffer.
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.Sh SEE ALSO
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.Xr ipsec 4 ,
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.Xr bus_dma 9 ,
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.Xr crypto 7 ,
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.Xr crypto 9 ,
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.Xr crypto_request 9 ,
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.Xr crypto_driver 9 ,
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.Xr crypto_session 9 ,
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.Xr mbuf 9
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.Xr uio 9
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