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author | Stefano Brivio <sbrivio@redhat.com> | 2021-04-29 16:59:20 +0200 |
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committer | Stefano Brivio <sbrivio@redhat.com> | 2021-04-29 17:15:26 +0200 |
commit | 605af213c5e0fa047f6d8caef5bcef61a0987c8d (patch) | |
tree | 45615e603964adee64bfecdc40e119bd33d77859 /icmp.c | |
parent | 50bcddabc9e2c0dbd313a61cda1606045a67a8de (diff) | |
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udp: Connection tracking for ephemeral, local ports, and related fixes
As we support UDP forwarding for packets that are sent to local
ports, we actually need some kind of connection tracking for UDP.
While at it, this commit introduces a number of vaguely related fixes
for issues observed while trying this out. In detail:
- implement an explicit, albeit minimalistic, connection tracking
for UDP, to allow usage of ephemeral ports by the guest and by
the host at the same time, by binding them dynamically as needed,
and to allow mapping address changes for packets with a loopback
address as destination
- set the guest MAC address whenever we receive a packet from tap
instead of waiting for an ARP request, and set it to broadcast on
start, otherwise DHCPv6 might not work if all DHCPv6 requests time
out before the guest starts talking IPv4
- split context IPv6 address into address we assign, global or site
address seen on tap, and link-local address seen on tap, and make
sure we use the addresses we've seen as destination (link-local
choice depends on source address). Similarly, for IPv4, split into
address we assign and address we observe, and use the address we
observe as destination
- introduce a clock_gettime() syscall right after epoll_wait() wakes
up, so that we can remove all the other ones and pass the current
timestamp to tap and socket handlers -- this is additionally needed
by UDP to time out bindings to ephemeral ports and mappings between
loopback address and a local address
- rename sock_l4_add() to sock_l4(), no semantic changes intended
- include <arpa/inet.h> in passt.c before kernel headers so that we
can use <netinet/in.h> macros to check IPv6 address types, and
remove a duplicate <linux/ip.h> inclusion
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Diffstat (limited to 'icmp.c')
-rw-r--r-- | icmp.c | 13 |
1 files changed, 9 insertions, 4 deletions
@@ -38,8 +38,10 @@ * @c: Execution context * @s: File descriptor number for socket * @events: epoll events bitmap + * @now: Current timestamp, unused */ -void icmp_sock_handler(struct ctx *c, int s, uint32_t events) +void icmp_sock_handler(struct ctx *c, int s, uint32_t events, + struct timespec *now) { struct in6_addr a6 = { .s6_addr = { 0, 0, 0, 0, 0, 0, 0, 0, @@ -51,6 +53,7 @@ void icmp_sock_handler(struct ctx *c, int s, uint32_t events) ssize_t n; (void)events; + (void)now; n = recvfrom(s, buf, sizeof(buf), MSG_DONTWAIT, (struct sockaddr *)&sr, &slen); @@ -79,13 +82,15 @@ void icmp_sock_handler(struct ctx *c, int s, uint32_t events) * @af: Address family, AF_INET or AF_INET6 * @msg: Input message * @count: Message count (always 1 for ICMP) + * @now: Current timestamp, unused * * Return: count of consumed packets (always 1, even if malformed) */ int icmp_tap_handler(struct ctx *c, int af, void *addr, - struct tap_msg *msg, int count) + struct tap_msg *msg, int count, struct timespec *now) { (void)count; + (void)now; if (af == AF_INET) { struct icmphdr *ih = (struct icmphdr *)msg[0].l4h; @@ -138,10 +143,10 @@ int icmp_sock_init(struct ctx *c) c->icmp.fd_min = INT_MAX; c->icmp.fd_max = 0; - if (c->v4 && (c->icmp.s4 = sock_l4_add(c, 4, IPPROTO_ICMP, 0)) < 0) + if (c->v4 && (c->icmp.s4 = sock_l4(c, AF_INET, IPPROTO_ICMP, 0)) < 0) return -1; - if (c->v6 && (c->icmp.s6 = sock_l4_add(c, 6, IPPROTO_ICMPV6, 0)) < 0) + if (c->v6 && (c->icmp.s6 = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, 0)) < 0) return -1; return 0; |