155 lines
4.4 KiB
C
155 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* SSH message parser.
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*
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* Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
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*/
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#ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H
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#define _SURFACE_AGGREGATOR_SSH_PARSER_H
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#include <linux/device.h>
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#include <linux/kfifo.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/surface_aggregator/serial_hub.h>
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/**
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* struct sshp_buf - Parser buffer for SSH messages.
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* @ptr: Pointer to the beginning of the buffer.
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* @len: Number of bytes used in the buffer.
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* @cap: Maximum capacity of the buffer.
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*/
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struct sshp_buf {
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u8 *ptr;
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size_t len;
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size_t cap;
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};
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/**
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* sshp_buf_init() - Initialize a SSH parser buffer.
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* @buf: The buffer to initialize.
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* @ptr: The memory backing the buffer.
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* @cap: The length of the memory backing the buffer, i.e. its capacity.
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*
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* Initializes the buffer with the given memory as backing and set its used
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* length to zero.
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*/
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static inline void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap)
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{
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buf->ptr = ptr;
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buf->len = 0;
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buf->cap = cap;
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}
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/**
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* sshp_buf_alloc() - Allocate and initialize a SSH parser buffer.
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* @buf: The buffer to initialize/allocate to.
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* @cap: The desired capacity of the buffer.
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* @flags: The flags used for allocating the memory.
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*
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* Allocates @cap bytes and initializes the provided buffer struct with the
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* allocated memory.
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*
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* Return: Returns zero on success and %-ENOMEM if allocation failed.
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*/
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static inline int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags)
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{
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u8 *ptr;
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ptr = kzalloc(cap, flags);
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if (!ptr)
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return -ENOMEM;
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sshp_buf_init(buf, ptr, cap);
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return 0;
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}
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/**
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* sshp_buf_free() - Free a SSH parser buffer.
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* @buf: The buffer to free.
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*
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* Frees a SSH parser buffer by freeing the memory backing it and then
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* resetting its pointer to %NULL and length and capacity to zero. Intended to
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* free a buffer previously allocated with sshp_buf_alloc().
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*/
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static inline void sshp_buf_free(struct sshp_buf *buf)
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{
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kfree(buf->ptr);
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buf->ptr = NULL;
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buf->len = 0;
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buf->cap = 0;
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}
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/**
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* sshp_buf_drop() - Drop data from the beginning of the buffer.
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* @buf: The buffer to drop data from.
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* @n: The number of bytes to drop.
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*
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* Drops the first @n bytes from the buffer. Re-aligns any remaining data to
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* the beginning of the buffer.
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*/
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static inline void sshp_buf_drop(struct sshp_buf *buf, size_t n)
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{
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memmove(buf->ptr, buf->ptr + n, buf->len - n);
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buf->len -= n;
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}
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/**
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* sshp_buf_read_from_fifo() - Transfer data from a fifo to the buffer.
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* @buf: The buffer to write the data into.
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* @fifo: The fifo to read the data from.
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*
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* Transfers the data contained in the fifo to the buffer, removing it from
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* the fifo. This function will try to transfer as much data as possible,
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* limited either by the remaining space in the buffer or by the number of
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* bytes available in the fifo.
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*
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* Return: Returns the number of bytes transferred.
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*/
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static inline size_t sshp_buf_read_from_fifo(struct sshp_buf *buf,
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struct kfifo *fifo)
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{
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size_t n;
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n = kfifo_out(fifo, buf->ptr + buf->len, buf->cap - buf->len);
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buf->len += n;
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return n;
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}
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/**
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* sshp_buf_span_from() - Initialize a span from the given buffer and offset.
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* @buf: The buffer to create the span from.
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* @offset: The offset in the buffer at which the span should start.
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* @span: The span to initialize (output).
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*
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* Initializes the provided span to point to the memory at the given offset in
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* the buffer, with the length of the span being capped by the number of bytes
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* used in the buffer after the offset (i.e. bytes remaining after the
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* offset).
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*
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* Warning: This function does not validate that @offset is less than or equal
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* to the number of bytes used in the buffer or the buffer capacity. This must
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* be guaranteed by the caller.
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*/
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static inline void sshp_buf_span_from(struct sshp_buf *buf, size_t offset,
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struct ssam_span *span)
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{
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span->ptr = buf->ptr + offset;
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span->len = buf->len - offset;
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}
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bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem);
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int sshp_parse_frame(const struct device *dev, const struct ssam_span *source,
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struct ssh_frame **frame, struct ssam_span *payload,
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size_t maxlen);
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int sshp_parse_command(const struct device *dev, const struct ssam_span *source,
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struct ssh_command **command,
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struct ssam_span *command_data);
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#endif /* _SURFACE_AGGREGATOR_SSH_PARSER_h */
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