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228542ddc6
Currently, if a non-SYN TCP packet arrives which doesn't match any existing connection, we simply ignore it. However RFC 9293, section 3.10.7.1 says we should respond with an RST to a non-SYN, non-RST packet that's for a CLOSED (i.e. non-existent) connection. This can arise in practice with migration, in cases where some error means we have to discard a connection. We destroy the connection with tcp_rst() in that case, but because the guest is stopped, we may not be able to deliver the RST packet on the tap interface immediately. This change ensures an RST will be sent if the guest tries to use the connection again. A similar situation can arise if a passt/pasta instance is killed or crashes, but is then replaced with another attached to the same guest. This can leave the guest with stale connections that the new passt instance isn't aware of. It's better to send an RST so the guest knows quickly these are broken, rather than letting them linger until they time out. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
85 lines
3 KiB
C
85 lines
3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later
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* Copyright (c) 2021 Red Hat GmbH
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* Author: Stefano Brivio <sbrivio@redhat.com>
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*/
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#ifndef TAP_H
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#define TAP_H
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#define ETH_HDR_INIT(proto) { .h_proto = htons_constant(proto) }
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/**
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* struct tap_hdr - tap backend specific headers
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* @vnet_len: Frame length (for qemu socket transport)
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*/
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struct tap_hdr {
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uint32_t vnet_len;
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} __attribute__((packed));
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/**
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* tap_hdr_iov() - struct iovec for a tap header
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* @c: Execution context
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* @taph: Pointer to tap specific header buffer
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*
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* Returns: A struct iovec covering the correct portion of @taph to use as the
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* tap specific header in the current configuration.
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*/
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static inline struct iovec tap_hdr_iov(const struct ctx *c,
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struct tap_hdr *thdr)
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{
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return (struct iovec){
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.iov_base = thdr,
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.iov_len = c->mode == MODE_PASST ? sizeof(*thdr) : 0,
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};
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}
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/**
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* tap_hdr_update() - Update the tap specific header for a frame
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* @taph: Tap specific header buffer to update
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* @l2len: Frame length (including L2 headers)
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*/
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static inline void tap_hdr_update(struct tap_hdr *thdr, size_t l2len)
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{
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if (thdr)
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thdr->vnet_len = htonl(l2len);
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}
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void *tap_push_l2h(const struct ctx *c, void *buf, uint16_t proto);
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void *tap_push_ip4h(struct iphdr *ip4h, struct in_addr src,
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struct in_addr dst, size_t l4len, uint8_t proto);
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void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
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struct in_addr dst, in_port_t dport,
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const void *in, size_t dlen);
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void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
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const void *in, size_t l4len);
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const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
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const struct in6_addr *src);
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void *tap_push_ip6h(struct ipv6hdr *ip6h,
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const struct in6_addr *src, const struct in6_addr *dst,
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size_t l4len, uint8_t proto, uint32_t flow);
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void tap_udp6_send(const struct ctx *c,
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const struct in6_addr *src, in_port_t sport,
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const struct in6_addr *dst, in_port_t dport,
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uint32_t flow, void *in, size_t dlen);
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void tap_icmp6_send(const struct ctx *c,
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const struct in6_addr *src, const struct in6_addr *dst,
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const void *in, size_t l4len);
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void tap_send_single(const struct ctx *c, const void *data, size_t l2len);
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size_t tap_send_frames(const struct ctx *c, const struct iovec *iov,
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size_t bufs_per_frame, size_t nframes);
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void eth_update_mac(struct ethhdr *eh,
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const unsigned char *eth_d, const unsigned char *eth_s);
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void tap_listen_handler(struct ctx *c, uint32_t events);
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void tap_handler_pasta(struct ctx *c, uint32_t events,
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const struct timespec *now);
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void tap_handler_passt(struct ctx *c, uint32_t events,
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const struct timespec *now);
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int tap_sock_unix_open(char *sock_path);
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void tap_sock_reset(struct ctx *c);
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void tap_sock_update_pool(void *base, size_t size);
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void tap_backend_init(struct ctx *c);
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void tap_flush_pools(void);
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void tap_handler(struct ctx *c, const struct timespec *now);
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void tap_add_packet(struct ctx *c, ssize_t l2len, char *p);
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#endif /* TAP_H */
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