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We verify that every packet we store in a pool (and every partial packet we retreive from it) has a length no longer than UINT16_MAX. This originated in the older packet pool implementation which stored packet lengths in a uint16_t. Now, that packets are represented by a struct iovec with its size_t length, this check serves only as a sanity / security check that we don't have some wildly out of range length due to a bug elsewhere. We have may reasons to (slightly) increase this limit in future, so in preparation, give this quantity an explicit name - PACKET_MAX_LEN. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
78 lines
2.3 KiB
C
78 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright (c) 2022 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#ifndef PACKET_H
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#define PACKET_H
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/* Maximum size of a single packet stored in pool, including headers */
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#define PACKET_MAX_LEN UINT16_MAX
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/**
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* struct pool - Generic pool of packets stored in a buffer
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* @buf: Buffer storing packet descriptors,
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* a struct vu_dev_region array for passt vhost-user mode
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* @buf_size: Total size of buffer,
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* 0 for passt vhost-user mode
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* @size: Number of usable descriptors for the pool
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* @count: Number of used descriptors for the pool
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* @pkt: Descriptors: see macros below
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*/
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struct pool {
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char *buf;
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size_t buf_size;
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size_t size;
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size_t count;
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struct iovec pkt[];
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};
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int vu_packet_check_range(void *buf, const char *ptr, size_t len);
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void packet_add_do(struct pool *p, size_t len, const char *start,
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const char *func, int line);
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void *packet_get_do(const struct pool *p, const size_t idx,
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size_t offset, size_t len, size_t *left,
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const char *func, int line);
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void pool_flush(struct pool *p);
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#define packet_add(p, len, start) \
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packet_add_do(p, len, start, __func__, __LINE__)
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#define packet_get(p, idx, offset, len, left) \
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packet_get_do(p, idx, offset, len, left, __func__, __LINE__)
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#define packet_get_try(p, idx, offset, len, left) \
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packet_get_do(p, idx, offset, len, left, NULL, 0)
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#define PACKET_POOL_DECL(_name, _size, _buf) \
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struct _name ## _t { \
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char *buf; \
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size_t buf_size; \
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size_t size; \
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size_t count; \
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struct iovec pkt[_size]; \
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}
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#define PACKET_POOL_INIT_NOCAST(_size, _buf, _buf_size) \
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{ \
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.buf_size = _buf_size, \
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.buf = _buf, \
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.size = _size, \
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}
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#define PACKET_POOL(name, size, buf, buf_size) \
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PACKET_POOL_DECL(name, size, buf) name = \
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PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
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#define PACKET_INIT(name, size, buf, buf_size) \
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(struct name ## _t) PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
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#define PACKET_POOL_NOINIT(name, size, buf) \
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PACKET_POOL_DECL(name, size, buf) name ## _storage; \
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static struct pool *name = (struct pool *)&name ## _storage
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#define PACKET_POOL_P(name, size, buf, buf_size) \
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PACKET_POOL(name ## _storage, size, buf, buf_size); \
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struct pool *name = (struct pool *)&name ## _storage
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#endif /* PACKET_H */
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