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.Dd September 24, 2020 .Dt CRYPTO_BUFFER 9 .Os .Sh NAME .Nm crypto_buffer .Nd symmetric cryptographic request buffers .Sh SYNOPSIS n opencrypto/cryptodev.h .Ft int .Fo crypto_apply .Fa "struct cryptop *crp" .Fa "int off" .Fa "int len" .Fa "int (*f)(void *, void *, u_int)" .Fa "void *arg" .Fc .Ft int .Fo crypto_apply_buf .Fa "struct crypto_buffer *cb" .Fa "int off" .Fa "int len" .Fa "int (*f)(void *, void *, u_int)" .Fa "void *arg" .Fc .Ft void * .Fo crypto_buffer_contiguous_subsegment .Fa "struct crypto_buffer *cb" .Fa "size_t skip" .Fa "size_t len" .Fc .Ft size_t .Fn crypto_buffer_len "struct crypto_buffer *cb" .Ft void * .Fo crypto_contiguous_subsegment .Fa "struct cryptop *crp" .Fa "size_t skip" .Fa "size_t len" .Fc .Ft void .Fo crypto_cursor_init .Fa "struct crypto_buffer_cursor *cc" .Fa "const struct crypto_buffer *cb" .Fc .Ft void .Fn crypto_cursor_advance "struct crypto_buffer_cursor *cc" "size_t amount" .Ft void .Fo crypto_cursor_copyback .Fa "struct crypto_buffer_cursor *cc" .Fa "int size" .Fa "const void *src" .Fc .Ft void .Fo crypto_cursor_copydata .Fa "struct crypto_buffer_cursor *cc" .Fa "int size" .Fa "void *dst" .Fc .Ft void .Fo crypto_cursor_copydata_noadv .Fa "struct crypto_buffer_cursor *cc" .Fa "int size" .Fa "void *dst" .Fc .Ft void * .Fn crypto_cursor_segbase "struct crypto_buffer_cursor *cc" .Ft size_t .Fn crypto_cursor_seglen "struct crypto_buffer_cursor *cc" .Ft bool .Fn CRYPTO_HAS_OUTPUT_BUFFER "struct cryptop *crp" .Sh DESCRIPTION Symmetric cryptographic requests use data buffers to describe the data to be modified. Requests can either specify a single data buffer whose contents are modified in place, or requests may specify separate data buffers for input and output. .Vt struct crypto_buffer provides an abstraction that permits cryptographic requests to operate on different types of buffers. .Vt struct crypto_cursor allows cryptographic drivers to iterate over a data buffer.
p .Fn CRYPTO_HAS_OUTPUT_BUFFER returns true if .Fa crp uses separate buffers for input and output and false if .Fa crp uses a single buffer.
p .Fn crypto_buffer_len returns the length of data buffer .Fa cb in bytes.
p .Fn crypto_apply_buf invokes a caller-supplied function to a region of the data buffer .Fa cb . The function .Fa f is called one or more times. For each invocation, the first argument to .Fa f is the value of .Fa arg passed to .Fn crypto_apply_buf . The second and third arguments to .Fa f are a pointer and length to a segment of the buffer mapped into the kernel. The function is called enough times to cover the .Fa len bytes of the data buffer which starts at an offset .Fa off . If any invocation of .Fa f returns a non-zero value, .Fn crypto_apply_buf immediately returns that value without invoking .Fa f on any remaining segments of the region, otherwise .Fn crypto_apply_buf returns the value from the final call to .Fa f . .Fn crypto_apply invokes the callback .Fa f on a region of the input data buffer for .Fa crp .
p .Fn crypto_buffer_contiguous_subsegment attempts to locate a single, virtually-contiguous segment of the data buffer .Fa cb . The segment must be .Fa len bytes long and start at an offset of .Fa skip bytes. If a segment is found, a pointer to the start of the segment is returned. Otherwise, .Dv NULL is returned. .Fn crypto_contiguous_subsegment attempts to locate a single, virtually-contiguous segment in the input data buffer for .Fa crp . .Ss Data Buffers Data buffers are described by an instance of .Vt struct crypto buffer . The .Fa cb_type member contains the type of the data buffer. The following types are supported: l -tag -width " CRYPTO_BUF_CONTIG" t Dv CRYPTO_BUF_NONE An invalid buffer. Used to mark the output buffer when a crypto request uses a single data buffer. t Dv CRYPTO_BUF_CONTIG An array of bytes mapped into the kernel's address space. t Dv CRYPTO_BUF_UIO A scatter/gather list of kernel buffers as described in .Xr uio 9 . t Dv CRYPTO_BUF_MBUF A network memory buffer as described in .Xr mbuf 9 . t Dv CRYPTO_BUF_VMPAGE A scatter/gather list of .Vt vm_page_t structures describing pages in the kernel's address space. This buffer type is only available if .Dv CRYPTO_HAS_VMPAGE is true. .El
p The structure also contains the following type-specific fields: l -tag -width " cb_vm_page_offset" t Fa cb_buf A pointer to the start of a .Dv CRYPTO_BUF_CONTIG data buffer. t Fa cb_buf_len The length of a .Dv CRYPTO_BUF_CONTIG data buffer t Fa cb_mbuf A pointer to a .Vt struct mbuf for .Dv CRYPTO_BUF_MBUF . t Fa cb_uio A pointer to a .Vt struct uio for .Dv CRYPTO_BUF_UIO . t Fa cb_vm_page A pointer to an array of .Vt struct vm_page for .Dv CRYPTO_BUF_VMPAGE . t Fa cb_vm_page_len The total amount of data included in the .Fa cb_vm_page array, in bytes. t Fa cb_vm_page_offset Offset in bytes in the first page of .Fa cb_vm_page where valid data begins. .El .Ss Cursors Cursors provide a mechanism for iterating over a data buffer. They are primarily intended for use in software drivers which access data buffers via virtual addresses.
p .Fn crypto_cursor_init initializes the cursor .Fa cc to reference the start of the data buffer .Fa cb .
p .Fn crypto_cursor_advance advances the cursor .Fa amount bytes forward in the data buffer.
p .Fn crypto_cursor_copyback copies .Fa size bytes from the local buffer pointed to by .Fa src into the data buffer associated with .Fa cc . The bytes are written to the current position of .Fa cc , and the cursor is then advanced by .Fa size bytes.
p .Fn crypto_cursor_copydata copies .Fa size bytes out of the data buffer associated with .Fa cc into a local buffer pointed to by .Fa dst . The bytes are read from the current position of .Fa cc , and the cursor is then advanced by .Fa size bytes.
p .Fn crypto_cursor_copydata_noadv is similar to .Fn crypto_cursor_copydata except that it does not change the current position of .Fa cc .
p .Fn crypto_cursor_segbase and .Fn crypto_cursor_seglen return the start and length, respectively, of the virtually-contiguous segment at the current position of .Fa cc . .Sh RETURN VALUES .Fn crypto_apply and .Fn crypto_apply_buf return the return value from the caller-supplied callback function.
p .Fn crypto_buffer_contiguous_subsegment , .Fn crypto_contiguous_subsegment , and .Fn crypto_cursor_segbase , return a pointer to a contiguous segment or .Dv NULL .
p .Fn crypto_buffer_len returns the length of a buffer in bytes.
p .Fn crypto_cursor_seglen returns the length in bytes of a contiguous segment.
p .Fn CRYPTO_HAS_OUTPUT_BUFFER returns true if the request uses a separate output buffer. .Sh SEE ALSO .Xr ipsec 4 , .Xr crypto 7 , .Xr bus_dma 9 , .Xr crypto 9 , .Xr crypto_driver 9 , .Xr crypto_request 9 , .Xr crypto_session 9 , .Xr mbuf 9 , .Xr uio 9 .Sh HISTORY The .Nm functions first appeared in .Fx 13 . .Sh AUTHORS The .Nm functions and this manual page were written by .An John Baldwin Aq Mt jhb@FreeBSD.org .