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* tcp: Fix comment to tcp_sock_consume()Stefano Brivio2023-10-041-1/+1
| | | | | | | | | Note that tcp_sock_consume() doesn't update ACK sequence counters anymore. Fixes: cc6d8286d104 ("tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timer") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* cppcheck: Work around bug in cppcheck 2.12.0David Gibson2023-10-041-0/+7
| | | | | | | | | cppcheck 2.12.0 (and maybe some other versions) things this if condition is always true, which is demonstrably not true. Work around the bug for now. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* cppcheck: Make many pointers constDavid Gibson2023-10-041-9/+9
| | | | | | | | | Newer versions of cppcheck (as of 2.12.0, at least) added a warning for pointers which could be declared to point at const data, but aren't. Based on that, make many pointers throughout the codebase const. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Use incremental rather than all-at-once siphash functionsDavid Gibson2023-09-301-22/+10
| | | | | | | | | | | | | | | | | | We have a bunch of variants of the siphash functions for different data sizes. The callers, in tcp.c, need to pack the various values they want to hash into a temporary structure, then call the appropriate version. We can avoid the copy into the temporary by directly using the incremental siphash functions. The length specific hash functions also have an undocumented constraint that the data pointer they take must, in fact, be aligned to avoid unaligned accesses, which may cause crashes on some architectures. So, prefer the incremental approach and remove the length-specific functions. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* siphash: Make siphash functions consistently return 64-bit resultsDavid Gibson2023-09-301-3/+4
| | | | | | | | | | | | | | Some of the siphas_*b() functions return 64-bit results, others 32-bit results, with no obvious pattern. siphash_32b() also appears to do this incorrectly - taking the 64-bit hash value and simply returning it truncated, rather than folding the two halves together. Since SipHash proper is defined to give a 64-bit hash, make all of them return 64-bit results. In the one caller which needs a 32-bit value, tcp_seq_init() do the fold down to 32-bits ourselves. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Consolidate and improve workarounds for clang-tidy issue 58992David Gibson2023-09-271-7/+1
| | | | | | | | | | | | | | | | | | | | | We have several workarounds for a clang-tidy bug where the checker doesn't recognize that a number of system calls write to - and therefore initialise - a socket address. We can't neatly use a suppression, because the bogus warning shows up some time after the actual system call, when we access a field of the socket address which clang-tidy erroneously thinks is uninitialised. Consolidate these workarounds into one place by using macros to implement wrappers around affected system calls which add a memset() of the sockaddr to silence clang-tidy. This removes the need for the individual memset() workarounds at the callers - and the somewhat longwinded explanatory comments. We can then use a #define to not include the hack in "real" builds, but only consider it for clang-tidy. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Avoid shadowing index(3)David Gibson2023-09-271-7/+7
| | | | | | | | | | | | | | | | | A classic gotcha of the standard C library is that its unwise to call any variable 'index' because it will shadow the standard string library function index(3). This can cause warnings from cppcheck amongst others, and it also means that if the variable is removed you tend to get confusing type errors (or sometimes nothing at all) instead of a nice simple "name is not defined" error. Strictly speaking this only occurs if <string.h> is included, but that is so common that as a rule it's best to just avoid it always. We have a number of places which hit this trap, so rename variables and parameters to avoid it. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Always send an ACK segment once the handshake is completedStefano Brivio2023-09-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The reporter is running a SMTP server behind pasta, and the client waits for the server's banner before sending any data. In turn, the server waits for our ACK after sending SYN,ACK, which never comes. If we use the ACK_IF_NEEDED indication to tcp_send_flag(), given that there's no pending data, we delay sending the ACK segment at the end of the three-way handshake until we have some data to send to the server. This was actually intended, as I thought we would lower the latency for new connections, but we can't assume that the client will start sending data first (SMTP is the typical example where this doesn't happen). And, trying out this patch with SSH (where the client starts sending data first), the reporter actually noticed we have a lower latency by forcing an ACK right away. Comparing a capture before the patch: 13:07:14.007704 IP 10.1.2.1.42056 > 10.1.2.140.1234: Flags [S], seq 1797034836, win 65535, options [mss 4096,nop,wscale 7], length 0 13:07:14.007769 IP 10.1.2.140.1234 > 10.1.2.1.42056: Flags [S.], seq 2297052481, ack 1797034837, win 65480, options [mss 65480,nop,wscale 7], length 0 13:07:14.008462 IP 10.1.2.1.42056 > 10.1.2.140.1234: Flags [.], seq 1:22, ack 1, win 65535, length 21 13:07:14.008496 IP 10.1.2.140.1234 > 10.1.2.1.42056: Flags [.], ack 22, win 512, length 0 13:07:14.011799 IP 10.1.2.140.1234 > 10.1.2.1.42056: Flags [P.], seq 1:515, ack 22, win 512, length 514 and after: 13:10:26.165364 IP 10.1.2.1.59508 > 10.1.2.140.1234: Flags [S], seq 4165939595, win 65535, options [mss 4096,nop,wscale 7], length 0 13:10:26.165391 IP 10.1.2.140.1234 > 10.1.2.1.59508: Flags [S.], seq 985607380, ack 4165939596, win 65480, options [mss 65480,nop,wscale 7], length 0 13:10:26.165418 IP 10.1.2.1.59508 > 10.1.2.140.1234: Flags [.], ack 1, win 512, length 0 13:10:26.165683 IP 10.1.2.1.59508 > 10.1.2.140.1234: Flags [.], seq 1:22, ack 1, win 512, length 21 13:10:26.165698 IP 10.1.2.140.1234 > 10.1.2.1.59508: Flags [.], ack 22, win 512, length 0 13:10:26.167107 IP 10.1.2.140.1234 > 10.1.2.1.59508: Flags [P.], seq 1:515, ack 22, win 512, length 514 the latency between the initial SYN segment and the first data transmission actually decreases from 792µs to 334µs. This is not statistically relevant as we have a single measurement, but it can't be that bad, either. Reported-by: cr3bs (from IRC) Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Correct handling of FIN,ACK followed by SYNDavid Gibson2023-09-081-1/+1
| | | | | | | | | | | | | | | | | | | | When the guest tries to establish a connection, it could give up on it by sending a FIN,ACK instead of a plain ACK to our SYN,ACK. It could then make a new attempt to establish a connection with the same addresses and ports with a new SYN. Although it's unlikely, it could send the 2nd SYN very shortly after the FIN,ACK resulting in both being received in the same batch of packets from the tap interface. Currently, we don't handle that correctly, when we receive a FIN,ACK on a not fully established connection we discard the remaining packets in the batch, and so will never process the 2nd SYN. Correct this by returning 1 from tcp_tap_handler() in this case, so we'll just consume the FIN,ACK and continue to process the rest of the batch. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Consolidate paths where we initiate reset on tap interfaceDavid Gibson2023-09-081-22/+25
| | | | | | | | | | | | | | | | | | | There are a number of conditions where we will issue a TCP RST in response to something unexpected we received from the tap interface. These occur in both tcp_data_from_tap() and tcp_tap_handler(). In tcp_tap_handler() use a 'goto out of line' technique to consolidate all these paths into one place. For the tcp_data_from_tap() cases use a negative return code and direct that to the same path in tcp_tap_handler(), its caller. In this case we want to discard all remaining packets in the batch we have received: even if they're otherwise good, they'll be invalidated when the guest receives the RST we're sending. This is subtly different from the case where we *receive* an RST, where we could in theory get a new SYN immediately afterwards. Clarify that with a common on the now common reset path. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Correctly handle RST followed rapidly by SYNDavid Gibson2023-09-081-2/+2
| | | | | | | | | | | | | | | | | Although it's unlikely in practice, the guest could theoretically reset one TCP connection then immediately start a new one with the same addressses and ports, such that we get an RST then a SYN in the same batch of received packets in tcp_tap_handler(). We don't correctly handle that unlikely case, because when we receive the RST, we discard any remaining packets in the batch so we'd never see the SYN. This could happen in either tcp_tap_handler() or tcp_data_from_tap(). Correct that by returning 1, so that the caller will continue calling tcp_tap_handler() on subsequent packets allowing us to process any subsequent SYN. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Return consumed packet count from tcp_data_from_tap()David Gibson2023-09-081-10/+15
| | | | | | | | | | Currently tcp_data_from_tap() is assumed to consume all packets remaining in the packet pool it is given. However there are some edge cases where that's not correct. In preparation for fixing those, change it to return a count of packets consumed and use that in its caller. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Never hash match closed connectionsDavid Gibson2023-09-081-1/+1
| | | | | | | | | | | | | | | >From a practical point of view, when a TCP connection ends, whether by FIN or by RST, we set the CLOSED event, then some time later we remove the connection from the hash table and clean it up. However, from a protocol point of view, once it's closed, it's gone, and any new packets with matching addresses and ports are either forming a new connection, or are invalid packets to discard. Enforce these semantics in the TCP hash logic by never hash matching closed connections. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Remove some redundant packet_get() operationsDavid Gibson2023-09-081-10/+4
| | | | | | | | | | | | Both tcp_data_from_tap() and tcp_tap_handler() call packet_get() to get the entire L4 packet length, then immediately call it again to check that the packet is long enough to include a TCP header. The features of packet_get() let us easily combine these together, we just need to adjust the length slightly, because we want the value to include the TCP header length. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, tap: Correctly advance through packets in tcp_tap_handler()David Gibson2023-09-081-13/+15
| | | | | | | | | | | | | | | | | | | | | | | | | In both tap4_handler() and tap6_handler(), once we've sorted incoming l3 packets into "sequences", we then step through all the packets in each TCP sequence calling tcp_tap_handler(). Or so it appears. In fact, tcp_tap_handler() doesn't take an index and always looks at packet 0 of the sequence, except when it calls tcp_data_from_tap() to process data packets. It appears to be written with the idea that the struct pool is a queue, from which it consumes packets as it processes them, but that's not how the pool data structure works - they are more like an array of packets. We only get away with this, because setup packets for TCP tend to come in separate batches (because we need to reply in between) and so we only get a bunch of packets for the same connection together when they're data packets (tcp_data_from_tap() has its own loop through packets). Correct this by adding an index parameter to tcp_tap_handler() and altering the loops in tap.c to step through the pool properly. Link: https://bugs.passt.top/show_bug.cgi?id=68 Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Remove broken pressure calculations for tcp_defer_handler()David Gibson2023-08-221-9/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | tcp_defer_handler() performs a potentially expensive linear scan of the connection table. So, to mitigate the cost of that we skip if if we're not under at least moderate pressure: either 30% of available connections or 30% (estimated) of available fds used. But, the calculation for this has been broken since it was introduced: we calculate "max_conns" based on c->tcp.conn_count, not TCP_MAX_CONNS, meaning we only exit early if conn_count is less than 30% of itself, i.e. never. If that calculation is "corrected" to be based on TCP_MAX_CONNS, it completely tanks the TCP CRR times for passt - from ~60ms to >1000ms on my laptop. My guess is that this is because in the case of many short lived connections, we're letting the table become much fuller before compacting it. That means that other places which perform a table scan now have to do much, much more. For the time being, simply remove the tests, since they're not doing anything useful. We can reintroduce them more carefully if we see a need for them. This also removes the only user of c->tcp.splice_conn_count, so that can be removed as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Move in_epoll flag out of common connection structureDavid Gibson2023-08-221-3/+3
| | | | | | | | | | | | | | | | | | | The in_epoll boolean is one of only two fields (currently) in the common structure shared between tap and spliced connections. It seems like it belongs there, because both tap and spliced connections use it, and it has roughly the same meaning. Roughly, however, isn't exactly: which fds this flag says are in the epoll varies between the two connection types, and are in type specific fields. So, it's only possible to meaningfully use this value locally in type specific code anyway. This common field is going to get in the way of more widespread generalisation of connection / flow tracking, so move it to separate fields in the tap and splice specific structures. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp: Don't pre-fill IPv4 destination address in headersDavid Gibson2023-08-221-7/+1
| | | | | | | | | | | | | | | | | Because packets sent on the tap interface will always be going to the guest/namespace, we more-or-less know what address they'll be going to. So we pre-fill this destination address in our header buffers for IPv4. We can't do the same for IPv6 because we could need either the global or link-local address for the guest. In future we're going to want more flexibility for the destination address, so this pre-filling will get in the way. Change the flow so we always fill in the IPv4 destination address for each packet, rather than prefilling it from proto_update_l2_buf(). In fact for TCP we already redundantly filled the destination for each packet anyway. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp: Don't include destination address in partially precomputed csumsDavid Gibson2023-08-221-40/+21
| | | | | | | | | | | | | | | | | | | | | | We partially prepopulate IP and TCP header structures including, amongst other things the destination address, which for IPv4 is always the known address of the guest/namespace. We partially precompute both the IPv4 header checksum and the TCP checksum based on this. In future we're going to want more flexibility with controlling the destination for IPv4 (as we already do for IPv6), so this precomputed value gets in the way. Therefore remove the IPv4 destination from the precomputed checksum and fold it into the checksum update when we actually send a packet. Doing this means we no longer need to recompute those partial sums when the destination address changes ({tcp,udp}_update_l2_buf()) and instead the computation can be moved to compile time. This means while we perform slightly more computations on each packet, we slightly reduce the amount of memory we need to access. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Consistent usage of ports in tcp_seq_init()David Gibson2023-08-221-2/+2
| | | | | | | | | | | | | | | In tcp_seq_init() the meaning of "src" and "dst" isn't really clear since it's used for connections in both directions. However, these values are just feeding a hash, so as long as we're consistent and include all the information we want, it doesn't really matter. Oddly, for the "src" side we supply the (tap side) forwarding address but the (tap side) endpoint port. This again doesn't really matter, but it's confusing. So swap this with dstport, so "src" is always forwarding and "dst" is always endpoint. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: More precise terms for addresses and portsDavid Gibson2023-08-221-46/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | In a number of places the comments and variable names we use to describe addresses and ports are ambiguous. It's not sufficient to describe a port as "tap-facing" or "socket-facing", because on both the tap side and the socket side there are two ports for the two ends of the connection. Similarly, "local" and "remote" aren't particularly helpful, because it's not necessarily clear whether we're talking from the point of view of the guest/namespace, the host, or passt itself. This patch makes a number of changes to be more precise about this. It introduces two new terms in aid of this: A "forwarding" address (or port) refers to an address which is local from the point of view of passt itself. That is a source address for traffic sent by passt, whether it's to the guest via the tap interface or to a host on the internet via a socket. The "endpoint" address (or port) is the reverse: a remote address from passt's point of view, the destination address for traffic sent by passt. Between them the "side" (either tap/guest-facing or sock/host-facing) and forwarding vs. endpoint unambiguously describes which address or port we're talking about. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap: Pass source address to protocol handler functionsDavid Gibson2023-08-221-11/+17
| | | | | | | | | | | The tap code passes the IPv4 or IPv6 destination address of packets it receives to the protocol specific code. Currently that protocol code doesn't use the source address, but we want it to in future. So, in preparation, pass the IPv4/IPv6 source address of tap packets to those functions as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* epoll: Split handling of listening TCP sockets into their own handlerDavid Gibson2023-08-131-29/+22
| | | | | | | | | | | | | | | | | tcp_sock_handler() handles both listening TCP sockets, and connected TCP sockets, but what it needs to do in those cases has essentially nothing in common. Therefore, give listening sockets their own epoll_type value and dispatch directly to their own handler from the top level. Furthermore, the two handlers need essentially entirely different information from the reference: we re-(ab)used the index field in the tcp_epoll_ref to indicate the port for the listening socket, but that's not the same meaning. So, switch listening sockets to their own reference type which we can lay out as we please. That lets us remove the listen and outbound fields from the normal (connected) tcp_epoll_ref, reducing it to just the connection table index. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* epoll: Split handling of TCP timerfds into its own handler functionDavid Gibson2023-08-131-11/+4
| | | | | | | | | | | | tcp_sock_handler() actually handles several different types of fd events. This includes timerfds that aren't sockets at all. The handling of these has essentially nothing in common with the other cases. So, give the TCP timers there own epoll_type value and dispatch directly to their handler. This also means we can remove the timer field from tcp_epoll_ref, the information it encoded is now implicit in the epoll_type value. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* epoll: Generalize epoll_ref to cover things other than socketsDavid Gibson2023-08-131-11/+11
| | | | | | | | | | | | | | The epoll_ref type includes fields for the IP protocol of a socket, and the socket fd. However, we already have a few things in the epoll which aren't protocol sockets, and we may have more in future. Rename these fields to an abstract "fd type" and file descriptor for more generality. Similarly, rather than using existing IP protocol numbers for the type, introduce our own number space. For now these just correspond to the supported protocols, but we'll expand on that in future. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Use C11 anonymous members to make poll refs less verbose to useDavid Gibson2023-08-041-23/+23
| | | | | | | | | | | | union epoll_ref has a deeply nested set of structs and unions to let us subdivide it into the various different fields we want. This means that referencing elements can involve an awkward long string of intermediate fields. Using C11 anonymous structs and unions lets us do this less clumsily. 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>
* tcp: Clear ACK_FROM_TAP_DUE also on unchanged ACK sequence from peerStefano Brivio2023-03-291-3/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit cc6d8286d104 ("tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timer"), we don't clear ACK_FROM_TAP_DUE whenever we process an ACK segment, but, more correctly, only if we're really not waiting for a further ACK segment, that is, only if the acknowledged sequence matches what we sent. In the new function implementing this, tcp_update_seqack_from_tap(), we also reset the retransmission counter and store the updated ACK sequence. Both should be done iff forward progress is acknowledged, implied by the fact that the new ACK sequence is greater than the one we previously stored. At that point, it looked natural to also include the statements that clear and set the ACK_FROM_TAP_DUE flag inside the same conditional block: if we're not making forward progress, the need for an ACK, or lack thereof, should remain unchanged. There might be cases where this isn't true, though: without the previous commit 4e73e9bd655c ("tcp: Don't special case the handling of the ack of a syn"), this would happen if a tap-side client initiated a connection, and the server didn't send any data. At that point we would never, in the established state of the connection, call tcp_update_seqack_from_tap() with reported forward progress. That issue itself is fixed by the previous commit, now, but clearing ACK_FROM_TAP_DUE only on ACK sequence progress doesn't really follow any logic. Clear the ACK_FROM_TAP_DUE flag regardless of reported forward progress. If we clear it when it's already unset, conn_flag() will do nothing with it. This doesn't fix any known functional issue, rather a conceptual one. Fixes: cc6d8286d104 ("tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timer") Reported-by: David Gibson <david@gibson.dropbear.id.au> Analysed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't special case the handling of the ack of a synDavid Gibson2023-03-291-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | TCP treats the SYN packets as though they occupied 1 byte in the logical data stream described by the sequence numbers. That is, the very first ACK (or SYN-ACK) each side sends should acknowledge a sequence number one greater than the initial sequence number given in the SYN or SYN-ACK it's responding to. In passt we were tracking that by advancing conn->seq_to_tap by one when we send a SYN or SYN-ACK (in tcp_send_flag()). However, we also initialized conn->seq_ack_from_tap, representing the acks we've already seen from the tap side, to ISN+1, meaning we treated it has having acknowledged the SYN before it actually did. There were apparently reasons for this in earlier versions, but it causes problems now. Because of this when we actually did receive the initial ACK or SYN-ACK, we wouldn't see the acknoweldged serial number as advancing, and so wouldn't clear the ACK_FROM_TAP_DUE flag. In most cases we'd get away because subsequent packets would clear the flag. However if one (or both) sides didn't send any data, the other side would (correctly) keep sending ISN+1 as the acknowledged sequence number, meaning we would never clear the ACK_FROM_TAP_DUE flag. That would mean we'd treat the connection as if we needed to retransmit (although we had 0 bytes to retransmit), and eventaully (after around 30s) reset the connection due to too many retransmits. Specifically this could cause the iperf3 throughput tests in the testsuite to fail if set for a long enough test period. Correct this by initializing conn->seq_ack_from_tap to the ISN and only advancing it when we actually get the first ACK (or SYN-ACK). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Clarify allowed state for tcp_data_from_tap()David Gibson2023-03-291-0/+5
| | | | | | | | | | | | | | Comments suggest that this should only be called for an ESTABLISHED connection. However, it's non-trivial to ascertain that from the actual control flow in the caller. Add an ASSERT() to make it very clear that this is only called in ESTABLISHED state. In fact, there were some circumstances where it could be called on a CLOSED connection. In a sense that is "established", but with that assert this does require specific (trivial) handling to avoid a spurious abort(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't reset ACK_TO_TAP_DUE on any ACK, reschedule timer as needed2023_03_21.1ee2f7cStefano Brivio2023-03-211-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is mostly symmetric with commit cc6d8286d104 ("tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timer"): we shouldn't reset the ACK_TO_TAP_DUE flag on any inbound ACK segment, but only once we acknowledge everything we received from the guest or the container. If we don't, a client might unnecessarily hold off further data, especially during slow start, and in general we won't converge to the usable bandwidth. This is very visible especially with traffic tests on links with non-negligible latency, such as in the reported issue. There, a public iperf3 server sometimes aborts the test due do what appears to be a low iperf3's --rcv-timeout (probably less than a second). Even if this doesn't happen, the throughput will converge to a fraction of the usable bandwidth. Clear ACK_TO_TAP_DUE if we acknowledged everything, set it if we didn't, and reschedule the timer in case the flag is still set as the timer expires. While at it, decrease the ACK timer interval to 10ms. A 50ms interval is short enough for any bandwidth-delay product I had in mind (local connections, or non-local connections with limited bandwidth), but here I am, testing 1gbps transfers to a peer with 100ms RTT. Indeed, we could eventually make the timer interval dependent on the current window and estimated bandwidth-delay product, but at least for the moment being, 10ms should be long enough to avoid any measurable syscall overhead, yet usable for any real-world application. Reported-by: Lukas Mrtvy <lukas.mrtvy@gmail.com> Link: https://bugs.passt.top/show_bug.cgi?id=44 Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: When a connection flag it set, don't negate it for debug printStefano Brivio2023-03-211-1/+1
| | | | | | | | | Fix a copy and paste typo I added in commit 5474bc5485d8 ("tcp, tcp_splice: Get rid of false positive CWE-394 Coverity warning from fls()") and --debug altogether. Fixes: 5474bc5485d8 ("tcp, tcp_splice: Get rid of false positive CWE-394 Coverity warning from fls()") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Fix false positive if cppcheck doesn't give a false positiveDavid Gibson2023-03-211-1/+1
| | | | | | | | | | | | | | | da46fdac "tcp: Suppress knownConditionTrueFalse cppcheck false positive" introduced a suppression to work around a cppcheck bug causing a false positive warning. However, the suppression will itself cause a spurious unmatchedSuppression warning if used with a version of cppcheck from before the bug was introduced. That includes the packaged version of cppcheck in Fedora. Suppress the unmatchedSuppression as well. Fixes: da46fdac3605 ("tcp: Suppress knownConditionTrueFalse cppcheck false positive") Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Work around weird false positives with cppcheck-2.9.1David Gibson2023-03-211-1/+1
| | | | | | | | | | | | | | | | | | Commit 89e38f55 "treewide: Fix header includes to build with musl" added extra #includes to work with musl. Unfortunately with the cppcheck version I'm using (cppcheck-2.9-1.fc37.x86_64 in Fedora 37) this causes weird false positives: specifically cppcheck seems to hit a #error in <bits/unistd.h> complaining about including it directly instead of via <unistd.h> (which is not something we're doing). I have no idea why that would be happening; but I'm guessing it has to be a bug in the cpp implementation in that cppcheck version. In any case, it's possible to work around this by moving the include of <unistd.h> before the include of <signal.h>. So, do that. Fixes: 89e38f55405d ("treewide: Fix header includes to build with musl") Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pasta: fix tcp port forwarding in auto modePaul Holzinger2023-03-211-5/+5
| | | | | | | | | | | | | | The logic in tcp_timer() was inverted. fwd_out should expose the host ports in the ns. Therfore it must read the ports on the host and then bind them in the netns. The same for fwd_in which checks ports in the ns and then exposes them on the host. Note that this only fixes tcp ports, udp does not seems to work at all right now with the auto mode. Signed-off-by: Paul Holzinger <pholzing@redhat.com> Fixes: 1128fa03fe73 ("Improve types and names for port forwarding configuration") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Clamp MSS value when queueing data to tap, also for pastaStefano Brivio2023-03-091-14/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tom reports that a pattern of repated ~1 MiB chunks downloads over NNTP over TLS, on Podman 4.4 using pasta as network back-end, results in pasta taking one full CPU thread after a while, and the download never succeeds. On that setup, we end up re-sending the same frame over and over, with a consistent 65 534 bytes size, and never get an acknowledgement from the tap-side client. This only happens for the default MTU value (65 520 bytes) or for values that are slightly smaller than that (down to 64 499 bytes). We hit this condition because the MSS value we use in tcp_data_from_sock(), only in pasta mode, is simply clamped to USHRT_MAX, and not to the actual size of the buffers we pre-cooked for sending, which is a bit less than that. It looks like we got away with it until commit 0fb7b2b9080a ("tap: Use different io vector bases depending on tap type") fixed the setting of iov_len. Luckily, since it's pasta, we're queueing up to two frames at a time, so the worst that can happen is a badly segmented TCP stream: we always have some space at the tail of the buffer. Clamp the MSS value to the appropriate maximum given by struct tcp{4,6}_buf_data_t, no matter if we're running in pasta or passt mode. While at it, fix the comments to those structs to reflect the current struct size. This is not really relevant for any further calculation or consideration, but it's convenient to know while debugging this kind of issues. Thanks to Tom for reporting the issue in a very detailed way and for providing a test setup. Reported-by: Tom Mombourquette <tom@devnode.com> Link: https://github.com/containers/podman/issues/17703 Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp, udp: Fix partial success return codes in {tcp,udp}_sock_init()Stefano Brivio2023-03-091-12/+9
| | | | | | | | | | | | The comments say we should return 0 on partial success, and an error code on complete failure. Rationale: if the user configures a port forwarding, and we succeed to bind that port for IPv4 or IPv6 only, that might actually be what the user intended. Adjust the two functions to reflect the comments. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp, udp, util: Pass socket creation errors all the way upStefano Brivio2023-03-091-10/+12
| | | | | | | | | ...starting from sock_l4(), pass negative error (errno) codes instead of -1. They will only be used in two commits from now, no functional changes intended here. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* treewide: Fix header includes to build with muslChris Kuhn2023-03-091-0/+1
| | | | | | | | | | | | | | | Roughly inspired from a patch by Chris Kuhn: fix up includes so that we can build against musl: glibc is more lenient as headers generally include a larger amount of other headers. Compared to the original patch, I only included what was needed directly in C files, instead of adding blanket includes in local header files. It's a bit more involved, but more consistent with the current (not ideal) situation. Reported-by: Chris Kuhn <kuhnchris+github@kuhnchris.eu> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* conf, icmp, tcp, udp: Add options to bind to outbound address and interfaceStefano Brivio2023-03-091-0/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I didn't notice earlier: libslirp (and slirp4netns) supports binding outbound sockets to specific IPv4 and IPv6 addresses, to force the source addresse selection. If we want to claim feature parity, we should implement that as well. Further, Podman supports specifying outbound interfaces as well, but this is simply done by resolving the primary address for an interface when the network back-end is started. However, since kernel version 5.7, commit c427bfec18f2 ("net: core: enable SO_BINDTODEVICE for non-root users"), we can actually bind to a specific interface name, which doesn't need to be validated in advance. Implement -o / --outbound ADDR to bind to IPv4 and IPv6 addresses, and --outbound-if4 and --outbound-if6 to bind IPv4 and IPv6 sockets to given interfaces. Given that it probably makes little sense to select addresses and routes from interfaces different than the ones given for outbound sockets, also assign those as "template" interfaces, by default, unless explicitly overridden by '-i'. For ICMP and UDP, we call sock_l4() to open outbound sockets, as we already needed to bind to given ports or echo identifiers, and we can bind() a socket only once: there, pass address (if any) and interface (if any) for the existing bind() and setsockopt() calls. For TCP, in general, we wouldn't otherwise bind sockets. Add a specific helper to do that. For UDP outbound sockets, we need to know if the final destination of the socket is a loopback address, before we decide whether it makes sense to bind the socket at all: move the block mangling the address destination before the creation of the socket in the IPv4 path. This was already the case for the IPv6 path. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Avoid (theoretical) resource leak (CWE-772) Coverity warningStefano Brivio2023-02-271-0/+3
| | | | | | | | | | If tcp_timer_ctl() gets a socket number greater than SOCKET_MAX (2 ^ 24), we return error but we don't close the socket. This is a rather formal issue given that, at least on Linux, socket numbers are monotonic and we're in general not allowed to open so many sockets. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Avoid false (but convoluted) positive Coverity CWE-476 warningStefano Brivio2023-02-271-1/+1
| | | | | | | | | | | | | | | If there are no TCP options in the header, tcp_tap_handler() will pass the corresponding pointer, fetched via packet_get(), as NULL to tcp_conn_from_sock_finish(), which in turn indirectly calls tcp_opt_get(). If there are no options, tcp_opt_get() will stop right away because the option length is indicated as zero. However, if the logic is complicated enough to follow for static checkers, adding an explicit check against NULL in tcp_opt_get() is probably a good idea. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp, tcp_splice: Get rid of false positive CWE-394 Coverity warning from fls()Stefano Brivio2023-02-271-4/+8
| | | | | | | | | | | | | | We use the return value of fls() as array index for debug strings. While fls() can return -1 (if no bit is set), Coverity Scan doesn't see that we're first checking the return value of another fls() call with the same bitmask, before using it. Call fls() once, store its return value, check it, and use the stored value as array index. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* treewide: Disable gcc strict aliasing rules as needed, drop workaroundsStefano Brivio2023-02-271-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recently, commit 4ddbcb9c0c55 ("tcp: Disable optimisations for tcp_hash()") worked around yet another issue we hit with gcc 12 and '-flto -O2': some stores affecting the input data to siphash_20b() were omitted altogether, and tcp_hash() wouldn't get the correct hash for incoming connections. Digging further into this revealed that, at least according to gcc's interpretation of C99 aliasing rules, passing pointers to functions with different types compared to the effective type of the object (for example, a uint8_t pointer to an anonymous struct, as it happens in tcp_hash()), doesn't guarantee that stores are not reordered across the function call. This means that, in general, our checksum and hash functions might not see parts of input data that was intended to be provided by callers. Not even switching from uint8_t to character types, which should be appropriate here, according to C99 (ISO/IEC 9899, TC3, draft N1256), section 6.5, "Expressions", paragraph 7: An object shall have its stored value accessed only by an lvalue expression that has one of the following types: [...] — a character type. does the trick. I guess this is also subject to interpretation: casting passed pointers to character types, and then using those as different types, might still violate (dubious) aliasing rules. Disable gcc strict aliasing rules for potentially affected functions, which, in turn, disables gcc's Type-Based Alias Analysis (TBAA) optimisations based on those function arguments. Drop the existing workarounds. Also the (seemingly?) bogus 'maybe-uninitialized' warning on the tcp_tap_handler() > tcp_hash() > siphash_20b() path goes away with -fno-strict-aliasing on siphash_20b(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Suppress knownConditionTrueFalse cppcheck false positiveStefano Brivio2023-02-271-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | cppcheck 2.10 reports: tcp.c:1815:12: style: Condition 'wnd>prev_scaled' is always false [knownConditionTrueFalse] if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) || ^ tcp.c:1808:8: note: Assignment 'wnd=((1<<(16+8))<(wnd))?(1<<(16+8)):(wnd)', assigned value is less than 1 wnd = MIN(MAX_WINDOW, wnd); ^ tcp.c:1811:19: note: Assuming condition is false if (prev_scaled == wnd) ^ tcp.c:1815:12: note: Condition 'wnd>prev_scaled' is always false if ((wnd > prev_scaled && wnd * 99 / 100 < prev_scaled) || ^ but this is not actually the case: wnd is typically greater than 1, and might very well be greater than prev_scaled as well. I bisected this down to cppcheck commit b4d455df487c ("Fix 11349: FP negativeIndex for clamped array index (#4627)") and reported findings at https://github.com/danmar/cppcheck/pull/4627. Suppress the warning for the moment being. Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Disable optimisations for tcp_hash()2023_02_22.4ddbcb9Stefano Brivio2023-02-221-0/+3
| | | | | | | | | | I'm not sure if we're breaking some aliasing rule here, but with gcc 12.2.1 on x86_64 and -flto, the siphash_20b() call in tcp_hash() doesn't see the connection address -- it gets all zeroes instead. Fix this temporarily by disabling optimisations for this tcp_hash(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Remove 'zero_len' goto from tcp_data_from_sockDavid Gibson2023-02-161-14/+12
| | | | | | | | | | This goto exists purely to move this exception case out of line. Although that does make the "normal" path a little clearer, it comes at the cost of not knowing how where control will flow after jumping to the zero_len label. The exceptional case isn't that long, so just put it inline. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Remove 'recvmsg' goto from tcp_data_from_sockDavid Gibson2023-02-161-6/+5
| | | | | | | This goto can be handled just as simply and more clearly with a do while. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* conf, tcp, udp: Exit if we fail to bind sockets for all given portsStefano Brivio2023-02-161-7/+18
| | | | | | | | | | | | | | passt supports ranges of forwarded ports as well as 'all' for TCP and UDP, so it might be convenient to proceed if we fail to bind only some of the desired ports. But if we fail to bind even a single port for a given specification, we're clearly, unexpectedly, conflicting with another network service. In that case, report failure and exit. Reported-by: Yalan Zhang <yalzhang@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Improve handling of fallback if socket pool is empty on new spliceDavid Gibson2023-02-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | When creating a new spliced connection, we need to get a socket in the other ns from the originating one. To avoid excessive ns switches we usually get these from a pool refilled on a timer. However, if the pool runs out we need a fallback. Currently that's done by passing -1 as the socket to tcp_splice_connnect() and running it in the target ns. This means that tcp_splice_connect() itself needs to have different cases depending on whether it's given an existing socket or not, which is a separate concern from what it's mostly doing. We change it to require a suitable open socket to be passed in, and ensuring in the caller that we have one. This requires adding the fallback paths to the caller, tcp_splice_new(). We use slightly different approaches for a socket in the init ns versus the guest ns. This also means that we no longer need to run tcp_splice_connect() itself in the guest ns, which allows us to remove a bunch of boilerplate code. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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