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* treewide: Rename MAC address fields for clarityDavid Gibson2024-08-211-2/+2
| | | | | | | | | | | c->mac isn't a great name, because it doesn't say whose mac address it is and it's not necessarily obvious in all the contexts we use it. Since this is specifically the address that we (passt/pasta) use on the tap interface, rename it to "our_tap_mac". Rename the "mac_guest" field to "guest_mac" to be grammatically consistent. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Standardise variable names for various packet lengthsDavid Gibson2024-05-021-3/+3
| | | | | | | | | | | | | | | | | | At various points we need to track the lengths of a packet including or excluding various different sets of headers. We don't always use the same variable names for doing so. Worse in some places we use the same name for different things: e.g. tcp_fill_headers[46]() use ip_len for the length including the IP headers, but then tcp_send_flag() which calls it uses it to mean the IP payload length only. To improve clarity, standardise on these names: dlen: L4 protocol payload length ("data length") l4len: plen + length of L4 protocol header l3len: l4len + length of IPv4/IPv6 header l2len: l3len + length of L2 (ethernet) header Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap: Implement tap_send() "slow path" in terms of fast pathDavid Gibson2024-03-141-3/+1
| | | | | | | | | | | | | | | | Most times we send frames to the guest it goes via tap_send_frames(). However "slow path" protocols - ARP, ICMP, ICMPv6, DHCP and DHCPv6 - go via tap_send(). As well as being a semantic duplication, tap_send() contains at least one serious problem: it doesn't properly handle short sends, which can be fatal on the qemu socket connection, since frame boundaries will get out of sync. Rewrite tap_send() to call tap_send_frames(). While we're there, rename it tap_send_single() for clarity. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Relicense to GPL 2.0, or any later versionStefano Brivio2023-04-061-1/+1
| | | | | | | | | | | | | | | | | | | In practical terms, passt doesn't benefit from the additional protection offered by the AGPL over the GPL, because it's not suitable to be executed over a computer network. Further, restricting the distribution under the version 3 of the GPL wouldn't provide any practical advantage either, as long as the passt codebase is concerned, and might cause unnecessary compatibility dilemmas. Change licensing terms to the GNU General Public License Version 2, or any later version, with written permission from all current and past contributors, namely: myself, David Gibson, Laine Stump, Andrea Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* arp, tap, util: Don't use perror() after seccomp filter is installedStefano Brivio2022-11-161-2/+4
| | | | | | | | | | | | | | | If stderr is closed, after we fork to background, glibc's implementation of perror() will try to re-open it by calling dup(), upon which the seccomp filter causes the process to terminate, because dup() is not included in the list of allowed syscalls. Replace perror() calls that might happen after isolation_postfork(). We could probably replace all of them, but early ones need a bit more attention as we have to check whether log.c functions work in early stages. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tap: Remove unhelpeful vnet_pre optimization from tap_send()David Gibson2022-10-191-1/+1
| | | | | | | | | | | | | | | | Callers of tap_send() can optionally use a small optimization by adding extra space for the 4 byte length header used on the qemu socket interface. tap_ip_send() is currently the only user of this, but this is used only for "slow path" ICMP and DHCP packets, so there's not a lot of value to the optimization. Worse, having the two paths here complicates the interface and makes future cleanups difficult, so just remove it. I have some plans to bring back the optimization in a more general way in future, but for now it's just in the way. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Make substructures for IPv4 and IPv6 specific context informationDavid Gibson2022-07-301-1/+1
| | | | | | | | | | | | The context structure contains a batch of fields specific to IPv4 and to IPv6 connectivity. Split those out into a sub-structure. This allows the conf_ip4() and conf_ip6() functions, which take the entire context but touch very little of it, to be given more specific parameters, making it clearer what it affects without stepping through the code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
* treewide: Mark constant references as constStefano Brivio2022-03-291-1/+1
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* treewide: Packet abstraction with mandatory boundary checksStefano Brivio2022-03-291-24/+27
| | | | | | | | | | | | | | | | | | | | Implement a packet abstraction providing boundary and size checks based on packet descriptors: packets stored in a buffer can be queued into a pool (without storage of its own), and data can be retrieved referring to an index in the pool, specifying offset and length. Checks ensure data is not read outside the boundaries of buffer and descriptors, and that packets added to a pool are within the buffer range with valid offset and indices. This implies a wider rework: usage of the "queueing" part of the abstraction mostly affects tap_handler_{passt,pasta}() functions and their callees, while the "fetching" part affects all the guest or tap facing implementations: TCP, UDP, ICMP, ARP, NDP, DHCP and DHCPv6 handlers. Suggested-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* arp, dhcp: Fix strict aliasing warnings reported by gcc 4.9 with -OfastStefano Brivio2022-02-281-1/+2
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Drop <linux/ipv6.h> include, carry own ipv6hdr and opt_hdr definitionsStefano Brivio2022-01-261-2/+0
| | | | | | | This is the only remaining Linux-specific include -- drop it to avoid clang-tidy warnings and to make code more portable. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Fix build with gcc 7, use std=c99, enable some more Clang checkersStefano Brivio2021-10-211-9/+9
| | | | | | | | | | | | | | Unions and structs, you all have names now. Take the chance to enable bugprone-reserved-identifier, cert-dcl37-c, and cert-dcl51-cpp checkers in clang-tidy. Provide a ffsl() weak declaration using gcc built-in. Start reordering includes, but that's not enough for the llvm-include-order checker yet. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* arp: Don't resolve own, configured IPv4 addressStefano Brivio2021-09-011-0/+4
| | | | | | | DHCP clients might try to resolve the assigned address to check if it's already in use: don't resolve the configured IPv4 address. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* arp: Don't answer announcements from guest or namespaceStefano Brivio2021-09-011-0/+6
| | | | | | | Depending on the configuration, the host might have the same address. Don't answer them to avoid a duplicate IP address detection. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add PASTA mode, major reworkStefano Brivio2021-07-171-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* qrap: Connect to the first available instance of passt, probe via ARP requestStefano Brivio2021-05-211-14/+1
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Connection tracking for ephemeral, local ports, and related fixesStefano Brivio2021-04-291-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* passt: Assorted fixes from "fresh eyes" reviewStefano Brivio2021-02-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A bunch of fixes not worth single commits at this stage, notably: - make buffer, length parameter ordering consistent in ARP, DHCP, NDP handlers - strict checking of buffer, message and option length in DHCP handler (a malicious client could have easily crashed it) - set up forwarding for IPv4 and IPv6, and masquerading with nft for IPv4, from demo script - get rid of separate slow and fast timers, we don't save any overhead that way - stricter checking of buffer lengths as passed to tap handlers - proper dequeuing from qemu socket back-end: I accidentally trashed messages that were bundled up together in a single tap read operation -- the length header tells us what's the size of the next frame, but there's no apparent limit to the number of messages we get with one single receive - rework some bits of the TCP state machine, now passive and active connection closes appear to be robust -- introduce a new FIN_WAIT_1_SOCK_FIN state indicating a FIN_WAIT_1 with a FIN flag from socket - streamline TCP option parsing routine - track TCP state changes to stderr (this is temporary, proper debugging and syslogging support pending) - observe that multiplying a number by four might very well change its value, and this happens to be the case for the data offset from the TCP header as we check if it's the same as the total length to find out if it's a duplicated ACK segment - recent estimates suggest that the duration of a millisecond is closer to a million nanoseconds than a thousand of them, this trend is now reflected into the timespec_diff_ms() convenience routine Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: New design and implementation with native Layer 4 socketsStefano Brivio2021-02-161-3/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a reimplementation, partially building on the earlier draft, that uses L4 sockets (SOCK_DGRAM, SOCK_STREAM) instead of SOCK_RAW, providing L4-L2 translation functionality without requiring any security capability. Conceptually, this follows the design presented at: https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Networking.md The most significant novelty here comes from TCP and UDP translation layers. In particular, the TCP state and translation logic follows the intent of being minimalistic, without reimplementing a full TCP stack in either direction, and synchronising as much as possible the TCP dynamic and flows between guest and host kernel. Another important introduction concerns addressing, port translation and forwarding. The Layer 4 implementations now attempt to bind on all unbound ports, in order to forward connections in a transparent way. While at it: - the qemu 'tap' back-end can't be used as-is by qrap anymore, because of explicit checks now introduced in qemu to ensure that the corresponding file descriptor is actually a tap device. For this reason, qrap now operates on a 'socket' back-end type, accounting for and building the additional header reporting frame length - provide a demo script that sets up namespaces, addresses and routes, and starts the daemon. A virtual machine started in the network namespace, wrapped by qrap, will now directly interface with passt and communicate using Layer 4 sockets provided by the host kernel. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* passt: Add IPv6 and NDP support, further fixes for IPv4 CTStefano Brivio2021-02-161-0/+1
| | | | Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* merd: Rename to PASSTStefano Brivio2021-02-161-2/+2
| | | | | | Plug A Simple Socket Transport. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* merd: ARP and DHCP handlers, connection tracking fixesStefano Brivio2021-02-161-0/+82
With this, merd provides a fully functional IPv4 environment to guests, requiring a single capability, CAP_NET_RAW. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>