cc65f31250
An n-sized pool, or a pool with n entries, doesn't include index n, only up to n - 1. I'm not entirely sure this sanity check actually covers any practical case, but I spotted this while debugging a hang in tap4_handler() (possibly due to malformed sequence entries from qemu). Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
137 lines
3.4 KiB
C
137 lines
3.4 KiB
C
// SPDX-License-Identifier: AGPL-3.0-or-later
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/* PASST - Plug A Simple Socket Transport
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* for qemu/UNIX domain socket mode
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*
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* PASTA - Pack A Subtle Tap Abstraction
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* for network namespace/tap device mode
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*
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* packet.c - Packet abstraction: add packets to pool, flush, get packet data
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*
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* Copyright (c) 2020-2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#include <limits.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <netinet/ip6.h>
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#include "packet.h"
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#include "util.h"
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#include "log.h"
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/**
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* packet_add_do() - Add data as packet descriptor to given pool
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* @p: Existing pool
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* @len: Length of new descriptor
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* @start: Start of data
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* @func: For tracing: name of calling function, NULL means no trace()
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* @line: For tracing: caller line of function call
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*/
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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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{
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size_t index = p->count;
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if (index >= p->size) {
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trace("add packet index %lu to pool with size %lu, %s:%i",
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index, p->size, func, line);
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return;
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}
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if (start < p->buf) {
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trace("add packet start %p before buffer start %p, %s:%i",
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start, p->buf, func, line);
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return;
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}
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if (start + len > p->buf + p->buf_size) {
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trace("add packet start %p, length: %lu, buffer end %p, %s:%i",
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start, len, p->buf + p->buf_size, func, line);
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return;
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}
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if (len > UINT16_MAX) {
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trace("add packet length %lu, %s:%i", len, func, line);
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return;
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}
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#if UINTPTR_MAX == UINT64_MAX
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if ((uintptr_t)start - (uintptr_t)p->buf > UINT32_MAX) {
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trace("add packet start %p, buffer start %p, %s:%i",
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start, p->buf, func, line);
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return;
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}
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#endif
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p->pkt[index].offset = start - p->buf;
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p->pkt[index].len = len;
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p->count++;
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}
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/**
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* packet_get_do() - Get data range from packet descriptor from given pool
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* @p: Packet pool
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* @index: Index of packet descriptor in pool
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* @offset: Offset of data range in packet descriptor
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* @len: Length of desired data range
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* @left: Length of available data after range, set on return, can be NULL
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* @func: For tracing: name of calling function, NULL means no trace()
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* @line: For tracing: caller line of function call
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*
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* Return: pointer to start of data range, NULL on invalid range or descriptor
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*/
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void *packet_get_do(const struct pool *p, size_t index, size_t offset,
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size_t len, size_t *left, const char *func, int line)
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{
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if (index >= p->size || index >= p->count) {
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if (func) {
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trace("packet %lu from pool size: %lu, count: %lu, "
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"%s:%i", index, p->size, p->count, func, line);
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}
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return NULL;
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}
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if (len > UINT16_MAX || len + offset > UINT32_MAX) {
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if (func) {
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trace("packet data length %lu, offset %lu, %s:%i",
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len, offset, func, line);
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}
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return NULL;
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}
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if (p->pkt[index].offset + len + offset > p->buf_size) {
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if (func) {
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trace("packet offset plus length %lu from size %lu, "
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"%s:%i", p->pkt[index].offset + len + offset,
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p->buf_size, func, line);
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}
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return NULL;
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}
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if (len + offset > p->pkt[index].len) {
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if (func) {
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trace("data length %lu, offset %lu from length %u, "
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"%s:%i", len, offset, p->pkt[index].len,
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func, line);
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}
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return NULL;
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}
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if (left)
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*left = p->pkt[index].len - offset - len;
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return p->buf + p->pkt[index].offset + offset;
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}
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/**
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* pool_flush() - Flush a packet pool
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* @p: Pointer to packet pool
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*/
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void pool_flush(struct pool *p)
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{
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p->count = 0;
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}
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