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* dhcpv6: Drop bogus option length test while checking for not-on-link IA_NAStefano Brivio2021-07-261-4/+1
| | | | | | | | | | | dhcpv6_opt() already reflects consumed bytes on the remaining length, and that we're not exceeding the message length. At this point, the remaining length is usually zero. While at it, drop a useless __packed__ attribute that triggers a gcc warning. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add PASTA mode, major reworkStefano Brivio2021-07-171-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PASTA (Pack A Subtle Tap Abstraction) provides quasi-native host connectivity to an otherwise disconnected, unprivileged network and user namespace, similarly to slirp4netns. Given that the implementation is largely overlapping with PASST, no separate binary is built: 'pasta' (and 'passt4netns' for clarity) both link to 'passt', and the mode of operation is selected depending on how the binary is invoked. Usage example: $ unshare -rUn # echo $$ 1871759 $ ./pasta 1871759 # From another terminal # udhcpc -i pasta0 2>/dev/null # ping -c1 pasta.pizza PING pasta.pizza (64.190.62.111) 56(84) bytes of data. 64 bytes from 64.190.62.111 (64.190.62.111): icmp_seq=1 ttl=255 time=34.6 ms --- pasta.pizza ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 34.575/34.575/34.575/0.000 ms # ping -c1 spaghetti.pizza PING spaghetti.pizza(2606:4700:3034::6815:147a (2606:4700:3034::6815:147a)) 56 data bytes 64 bytes from 2606:4700:3034::6815:147a (2606:4700:3034::6815:147a): icmp_seq=1 ttl=255 time=29.0 ms --- spaghetti.pizza ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 0ms rtt min/avg/max/mdev = 28.967/28.967/28.967/0.000 ms This entails a major rework, especially with regard to the storage of tracked connections and to the semantics of epoll(7) references. Indexing TCP and UDP bindings merely by socket proved to be inflexible and unsuitable to handle different connection flows: pasta also provides Layer-2 to Layer-2 socket mapping between init and a separate namespace for local connections, using a pair of splice() system calls for TCP, and a recvmmsg()/sendmmsg() pair for UDP local bindings. For instance, building on the previous example: # ip link set dev lo up # iperf3 -s $ iperf3 -c ::1 -Z -w 32M -l 1024k -P2 | tail -n4 [SUM] 0.00-10.00 sec 52.3 GBytes 44.9 Gbits/sec 283 sender [SUM] 0.00-10.43 sec 52.3 GBytes 43.1 Gbits/sec receiver iperf Done. epoll(7) references now include a generic part in order to demultiplex data to the relevant protocol handler, using 24 bits for the socket number, and an opaque portion reserved for usage by the single protocol handlers, in order to track sockets back to corresponding connections and bindings. A number of fixes pertaining to TCP state machine and congestion window handling are also included here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* dhcp, ndp, dhcpv6: Support for multiple DNS servers, search listStefano Brivio2021-05-211-9/+96
| | | | | | | | | | | Add support for a variable amount of DNS servers, including zero, from /etc/resolv.conf, in DHCP, NDP and DHCPv6 implementations. Introduce support for domain search list for DHCP (RFC 3397), NDP (RFC 8106), and DHCPv6 (RFC 3646), also sourced from /etc/resolv.conf. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Connection tracking for ephemeral, local ports, and related fixesStefano Brivio2021-04-291-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* dhcpv6: Don't pass DNS option, it already comes from SLAACStefano Brivio2021-04-221-5/+0
| | | | | | | | | | | | It looks like some versions of ISC's IPv6 dhclient not only discard the DNS Recursive Name Server option if other options (Domain Search List? FQDN?) are absent, but they also drop existing entries configured via SLAAC from /etc/resolv.conf. Don't pass option 23 until I figure this out, it's anyway redundant as we pass DNS information via SLAAC (RFC 8106). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* dhcpv6: Subtract option length before returning one optionStefano Brivio2021-04-221-1/+2
| | | | | | | | dhcpv6_opt() needs to subtract option length _before_ returning, so that callers can conveniently pass the remaining length on subsequent calls. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* dhcpv6: Fix REPLY messages with NotOnLink status codeStefano Brivio2021-04-211-9/+19
| | | | | | | | | | | | The NotOnLink status code needs to be appended to the existing IA content, because if we omit the requested addresses in the reply, ISC's dhclient handles it as a NoAddrsAvail response. Also fix length accounting (we would send a bunch of zeroes after the IA otherwise), and print an informational message with the requested address, if it's not appropriate for the link. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Introduce a DHCPv6 serverStefano Brivio2021-04-131-0/+502
This implementation, similarly to the IPv4 DHCP one, hands out a single address, which is the same as the upstream address for the host. This avoids the need for address translation as long as the client runs a DHCPv6 client. The NDP "Managed" flag is now set in Router Advertisements. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>