| 1 |
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| 2 | |
| 3 | * SSH message parser.
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| 4 | *
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| 5 | * Copyright (C) 2019-2022 Maximilian Luz <[email protected]>
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| 6 |
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| 7 |
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| 8 | #ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H
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| 9 | #define _SURFACE_AGGREGATOR_SSH_PARSER_H
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| 10 |
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| 11 | #include <linux/device.h>
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| 12 | #include <linux/kfifo.h>
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| 13 | #include <linux/slab.h>
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| 14 | #include <linux/types.h>
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| 15 |
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| 16 | #include <linux/surface_aggregator/serial_hub.h>
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| 17 |
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| 18 | |
| 19 | * struct sshp_buf - Parser buffer for SSH messages.
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| 20 | * @ptr: Pointer to the beginning of the buffer.
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| 21 | * @len: Number of bytes used in the buffer.
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| 22 | * @cap: Maximum capacity of the buffer.
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| 23 |
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| 24 | struct sshp_buf {
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| 25 | u8 *ptr;
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| 26 | size_t len;
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| 27 | size_t cap;
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| 28 | };
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| 29 |
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| 30 | |
| 31 | * sshp_buf_init() - Initialize a SSH parser buffer.
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| 32 | * @buf: The buffer to initialize.
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| 33 | * @ptr: The memory backing the buffer.
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| 34 | * @cap: The length of the memory backing the buffer, i.e. its capacity.
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| 35 | *
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| 36 | * Initializes the buffer with the given memory as backing and set its used
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| 37 | * length to zero.
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| 38 |
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| 39 | static inline void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap)
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| 40 | {
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| 41 | buf->ptr = ptr;
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| 42 | buf->len = 0;
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| 43 | buf->cap = cap;
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| 44 | }
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| 45 |
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| 46 | |
| 47 | * sshp_buf_alloc() - Allocate and initialize a SSH parser buffer.
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| 48 | * @buf: The buffer to initialize/allocate to.
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| 49 | * @cap: The desired capacity of the buffer.
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| 50 | * @flags: The flags used for allocating the memory.
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| 51 | *
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| 52 | * Allocates @cap bytes and initializes the provided buffer struct with the
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| 53 | * allocated memory.
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| 54 | *
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| 55 | * Return: Returns zero on success and %-ENOMEM if allocation failed.
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| 56 |
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| 57 | static inline int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags)
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| 58 | {
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| 59 | u8 *ptr;
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| 60 |
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| 61 | ptr = kzalloc(cap, flags);
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| 62 | if (!ptr)
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| 63 | return -ENOMEM;
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| 64 |
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| 65 | sshp_buf_init(buf, ptr, cap);
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| 66 | return 0;
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| 67 | }
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| 68 |
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| 69 | |
| 70 | * sshp_buf_free() - Free a SSH parser buffer.
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| 71 | * @buf: The buffer to free.
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| 72 | *
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| 73 | * Frees a SSH parser buffer by freeing the memory backing it and then
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| 74 | * resetting its pointer to %NULL and length and capacity to zero. Intended to
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| 75 | * free a buffer previously allocated with sshp_buf_alloc().
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| 76 |
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| 77 | static inline void sshp_buf_free(struct sshp_buf *buf)
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| 78 | {
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| 79 | kfree(buf->ptr);
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| 80 | buf->ptr = NULL;
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| 81 | buf->len = 0;
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| 82 | buf->cap = 0;
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| 83 | }
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| 84 |
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| 85 | |
| 86 | * sshp_buf_drop() - Drop data from the beginning of the buffer.
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| 87 | * @buf: The buffer to drop data from.
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| 88 | * @n: The number of bytes to drop.
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| 89 | *
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| 90 | * Drops the first @n bytes from the buffer. Re-aligns any remaining data to
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| 91 | * the beginning of the buffer.
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| 92 |
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| 93 | static inline void sshp_buf_drop(struct sshp_buf *buf, size_t n)
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| 94 | {
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| 95 | memmove(buf->ptr, buf->ptr + n, buf->len - n);
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| 96 | buf->len -= n;
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| 97 | }
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| 98 |
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| 99 | |
| 100 | * sshp_buf_read_from_fifo() - Transfer data from a fifo to the buffer.
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| 101 | * @buf: The buffer to write the data into.
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| 102 | * @fifo: The fifo to read the data from.
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| 103 | *
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| 104 | * Transfers the data contained in the fifo to the buffer, removing it from
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| 105 | * the fifo. This function will try to transfer as much data as possible,
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| 106 | * limited either by the remaining space in the buffer or by the number of
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| 107 | * bytes available in the fifo.
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| 108 | *
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| 109 | * Return: Returns the number of bytes transferred.
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| 110 |
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| 111 | static inline size_t sshp_buf_read_from_fifo(struct sshp_buf *buf,
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| 112 | struct kfifo *fifo)
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| 113 | {
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| 114 | size_t n;
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| 115 |
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| 116 | n = kfifo_out(fifo, buf->ptr + buf->len, buf->cap - buf->len);
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| 117 | buf->len += n;
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| 118 |
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| 119 | return n;
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| 120 | }
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| 121 |
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| 122 | |
| 123 | * sshp_buf_span_from() - Initialize a span from the given buffer and offset.
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| 124 | * @buf: The buffer to create the span from.
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| 125 | * @offset: The offset in the buffer at which the span should start.
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| 126 | * @span: The span to initialize (output).
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| 127 | *
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| 128 | * Initializes the provided span to point to the memory at the given offset in
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| 129 | * the buffer, with the length of the span being capped by the number of bytes
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| 130 | * used in the buffer after the offset (i.e. bytes remaining after the
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| 131 | * offset).
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| 132 | *
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| 133 | * Warning: This function does not validate that @offset is less than or equal
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| 134 | * to the number of bytes used in the buffer or the buffer capacity. This must
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| 135 | * be guaranteed by the caller.
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| 136 |
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| 137 | static inline void sshp_buf_span_from(struct sshp_buf *buf, size_t offset,
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| 138 | struct ssam_span *span)
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| 139 | {
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| 140 | span->ptr = buf->ptr + offset;
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| 141 | span->len = buf->len - offset;
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| 142 | }
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| 143 |
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| 144 | bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem);
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| 145 |
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| 146 | int sshp_parse_frame(const struct device *dev, const struct ssam_span *source,
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| 147 | struct ssh_frame **frame, struct ssam_span *payload,
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| 148 | size_t maxlen);
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| 149 |
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| 150 | int sshp_parse_command(const struct device *dev, const struct ssam_span *source,
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| 151 | struct ssh_command **command,
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| 152 | struct ssam_span *command_data);
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| 153 |
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| 154 | #endif
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