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* 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>
* tcp: Split pool lookup from creating new sockets in tcp_conn_new_sock()David Gibson2023-02-141-25/+28
| | | | | | | | | | | | | | tcp_conn_new_sock() first looks for a socket in a pre-opened pool, then if that's empty creates a new socket in the init namespace. Both parts of this are duplicated in other places: the pool lookup logic is duplicated in tcp_splice_new(), and the socket opening logic is duplicated in tcp_sock_refill_pool(). Split the function into separate parts so we can remove both these duplications. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Move socket pool declarations aroundDavid Gibson2023-02-141-37/+4
| | | | | | | | | | | | | | | | | tcp_splice.c has some explicit extern declarations to access the socket pools. This is pretty dangerous - if we changed the type of these variables in tcp.c, we'd have tcp.c and tcp_splice.c using the same memory in different ways with no compiler error. So, move the extern declarations to tcp_conn.h so they're visible to both tcp.c and tcp_splice.c, but not the rest of pasta. In fact the pools for the guest namespace are necessarily only used by tcp_splice.c - we have no sockets on the guest side if we're not splicing. So move those declarations and the functions that deal exclusively with them to tcp_splice.c Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Split init and ns cases for tcp_sock_refill()David Gibson2023-02-141-32/+21
| | | | | | | | | | With the creation of the tcp_sock_refill_pool() helper, the ns==true and ns==false paths for tcp_sock_refill() now have almost nothing in common. Split the two versions into tcp_sock_refill_init() and tcp_sock_refill_ns() functions. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Make a helper to refill each socket poolDavid Gibson2023-02-141-30/+33
| | | | | | | | | | | | | | | tcp_sock_refill() contains two near-identical loops to refill the IPv4 and IPv6 socket pools. In addition, if we get an error on the IPv4 pool we exit early and won't attempt to refill the IPv6 pool. At least theoretically, these are independent from each other and there's value to filling up either pool without the other. So, there's no strong reason to give up on one because the other failed. Address both of these with a helper function 'tcp_sock_refill_pool()' to refill a single given pool. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Make assertions actually usefulDavid Gibson2023-02-121-5/+4
| | | | | | | | | | | | | | | | | | There are some places in passt/pasta which #include <assert.h> and make various assertions. If we hit these something has already gone wrong, but they're there so that we a useful message instead of cryptic misbehaviour if assumptions we thought were correct turn out not to be. Except.. the glibc implementation of assert() uses syscalls that aren't in our seccomp filter, so we'll get a SIGSYS before it actually prints the message. Work around this by adding our own ASSERT() implementation using our existing err() function to log the message, and an abort(). The abort() probably also won't work exactly right with seccomp, but once we've printed the message, dying with a SIGSYS works just as well as dying with a SIGABRT. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Reset ACK_FROM_TAP_DUE flag only as needed, update timerStefano Brivio2023-02-121-14/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | David reports that TCP transfers might stall, especially with smaller socket buffer sizes, because we reset the ACK_FROM_TAP_DUE flag, in tcp_tap_handler(), whenever we receive an ACK segment, regardless of its sequence number and the fact that we might still be waiting for one. This way, we might fail to re-transmit frames on ACK timeouts. We need, instead, to: - indicate with the @retrans field only re-transmissions for the same data sequences. If we make progress, it should be reset, given that it's used to abort a connection when we exceed a given number of re-transmissions for the same data - unset the ACK_FROM_TAP_DUE flag if and only if the acknowledged sequence is the same as the last one we sent, as suggested by David - keep it set otherwise, if progress was done but not all the data we sent was acknowledged, and update the expiration of the ACK timeout Add a new helper for these purposes, tcp_update_seqack_from_tap(). To extend the ACK timeout, the new helper sets the ACK_FROM_TAP_DUE flag, even if it was already set, and conn_flag_do() triggers a timer update. This part should be revisited at a later time, because, strictly speaking, ACK_FROM_TAP_DUE isn't a flag anymore. One possibility might be to introduce another connection attribute for events affecting timer deadlines. Reported-by: David Gibson <david@gibson.dropbear.id.au> Link: https://bugs.passt.top/show_bug.cgi?id=41 Suggested-by: David Gibson <david@gibson.dropbear.id.au> Fixes: be5bbb9b0681 ("tcp: Rework timers to use timerfd instead of periodic bitmap scan") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Use abstracted tap headerDavid Gibson2023-01-231-55/+30
| | | | | | | | | Update the TCP code to use the tap layer abstractions for initializing and updating the L2 and lower headers. This will make adding other tap backends in future easier. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Consolidate calculation of total frame sizeDavid Gibson2023-01-231-19/+16
| | | | | | | | | | | | | tcp_l2_buf_fill_headers() returns the size of the generated frame including the ethernet header. The caller then adds on the size of the vnet_len field to get the total frame size to be passed to the tap device. Outside the tap code, though, we never care about the ethernet header size only the final total size we need to put into an iovec. So, consolidate the total frame size calculation within tcp_l2_buf_fill_headers(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Remove redundant and incorrect initialization from *_iov_init()David Gibson2023-01-231-6/+2
| | | | | | | | | | tcp_sock[46]_iov_init() initialize the length of each iovec buffer to MSS_DEFAULT. That will always be overwritten before use in tcp_data_to_tap, so it's redundant. It also wasn't correct, because it didn't correctly account for the header lengths in all cases. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* util: Parameterize ethernet header initializer macroDavid Gibson2023-01-231-4/+4
| | | | | | | | | We have separate IPv4 and IPv6 versions of a macro to construct an initializer for ethernet headers. However, now that we have htons_constant it's easy to simply paramterize this with the ethernet protocol number. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp, udp: Use named field initializers in iov_init functionsDavid Gibson2023-01-231-14/+12
| | | | | | | | | | Both the TCP and UDP iov_init functions have some large structure literals defined in "field order" style. These are pretty hard to read since it's not obvious what value corresponds to what field. Use named field style initializers instead to make this clearer. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap, tcp: Move tap send path to tap.cDavid Gibson2023-01-231-81/+4
| | | | | | | | | | The functions which do the final steps of sending TCP packets on through the tap interface - tcp_l2_buf_flush*() - no longer have anything that's actually specific to TCP in them, other than comments and names. Move them all to tap.c. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Combine two parts of pasta tap send path togetherDavid Gibson2023-01-231-22/+18
| | | | | | | | | | | tcp_l2_buf_flush() open codes the loop across each frame in a group, but but calls tcp_l2_buf_write_one() to send each frame to the pasta tuntap device. Combine these two pasta-specific operations into tcp_l2_buf_flush_pasta() which is a little cleaner and will enable further cleanups. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Improve interface to tcp_l2_buf_flush()David Gibson2023-01-231-37/+26
| | | | | | | | | | Currently this takes a msghdr, but the only thing we actually care about in there is the io vector. Make it take an io vector directly. We also have a weird side effect of zeroing @buf_used. Just pass this by value and zero it in the caller instead. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't compute total bytes in a message until we need itDavid Gibson2023-01-231-35/+18
| | | | | | | | | | | | | | | | | | | tcp[46]_l2_buf_bytes keep track of the total number of bytes we have queued to send to the tap interface. tcp_l2_buf_flush_passt() uses this to determine if sendmsg() has sent all the data we requested, or whether we need to resend a trailing portion. However, the logic for finding where we're up to in the case of a short sendmsg() can equally well tell whether we've had one at all, without knowing the total number in advance. This does require an extra loop after each sendmsg(), but it's doing simple arithmetic on values we've already been accessing, and it leads to overall simpler code. tcp[46]_l2_flags_buf_bytes were being calculated, but never used for anything, so simply remove them. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 06:11:38 +0000