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* flow, tcp: Generalise connection typesDavid Gibson2023-12-041-17/+7
| | | | | | | | | | | | Currently TCP connections use a 1-bit selector, 'spliced', to determine the rest of the contents of the structure. We want to generalise the TCP connection table to other types of flows in other protocols. Make a start on this by replacing the tcp_conn_common structure with a new flow_common structure with an enum rather than a simple boolean indicating the type of flow. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't use TCP_WINDOW_CLAMPDavid Gibson2023-11-101-4/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On the L2 tap side, we see TCP headers and know the TCP window that the ultimate receiver is advertising. In order to avoid unnecessary buffering within passt/pasta (or by the kernel on passt/pasta's behalf) we attempt to advertise that window back to the original sock-side sender using TCP_WINDOW_CLAMP. However, TCP_WINDOW_CLAMP just doesn't work like this. Prior to kernel commit 3aa7857fe1d7 ("tcp: enable mid stream window clamp"), it simply had no effect on established sockets. After that commit, it does affect established sockets but doesn't behave the way we need: * It appears to be designed only to shrink the window, not to allow it to re-expand. * More importantly, that commit has a serious bug where if the setsockopt() is made when the existing kernel advertised window for the socket happens to be zero, it will now become locked at zero, stopping any further data from being received on the socket. Since this has never worked as intended, simply remove it. It might be possible to re-implement the intended behaviour by manipulating SO_RCVBUF, so we leave a comment to that effect. This kernel bug is the underlying cause of both the linked passt bug and the linked podman bug. We attempted to fix this before with passt commit d3192f67 ("tcp: Force TCP_WINDOW_CLAMP before resetting STALLED flag"). However while that commit masked the bug for some cases, it didn't really address the problem. Fixes: d3192f67c492 ("tcp: Force TCP_WINDOW_CLAMP before resetting STALLED flag") Link: https://github.com/containers/podman/issues/20170 Link: https://bugs.passt.top/show_bug.cgi?id=74 Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp_splice: Rename sides of connection from a/b to 0/1David Gibson2023-11-071-26/+19
| | | | | | | | | | | | | Each spliced connection has two mostly, although not entirely, symmetric sides. We currently call those "a" and "b" and have different fields in the connection structure for each one. We can better exploit that symmetry if we use two element arrays rather thatn separately named fields. Do that in the places we can, and for the others change the "a"/"b" terminology to 0/1 to match. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* cppcheck: Make many pointers constDavid Gibson2023-10-041-1/+1
| | | | | | | | | 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>
* tcp: Move in_epoll flag out of common connection structureDavid Gibson2023-08-221-2/+4
| | | | | | | | | | | | | | | | | | | 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: More precise terms for addresses and portsDavid Gibson2023-08-221-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* epoll: Generalize epoll_ref to cover things other than socketsDavid Gibson2023-08-131-2/+2
| | | | | | | | | | | | | | 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>
* 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>
* Fix definitions of SOCKET_MAX, TCP_MAX_CONNSStefano Brivio2023-02-271-1/+1
| | | | | | | | ...and, given that I keep getting this wrong, add a convenience macro, MAX_FROM_BITS(). 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 Gibson2023-02-141-0/+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 Gibson2023-02-141-0/+1
| | | | | | | | | | | | | | 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 Gibson2023-02-141-2/+8
| | | | | | | | | | | | | | | | | 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: Pass union tcp_conn pointer to destroy and splice timer functionsStefano Brivio2022-11-251-2/+2
| | | | | | | | | | | | The pointers are actually the same, but we later pass the container union to tcp_table_compact(), which might zero the size of the whole union, and this confuses Coverity Scan. Given that we have pointers to the container union to start with, just pass those instead, all the way down to tcp_table_compact(). Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* inany: Helper functions for handling addresses which could be IPv4 or IPv6David Gibson2022-11-251-13/+2
| | | | | | | | | | | | | | struct tcp_conn stores an address which could be IPv6 or IPv4 using a union. We can do this without an additional tag by encoding IPv4 addresses as IPv4-mapped IPv6 addresses. This approach is useful wider than the specific place in tcp_conn, so expose a new 'union inany_addr' like this from a new inany.h. Along with that create a number of helper functions to make working with these "inany" addresses easier. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Don't store hash bucket in connection structuresDavid Gibson2022-11-251-5/+0
| | | | | | | | | | | | | | | Currently when we insert a connection into the hash table, we store its bucket number so we can find it when removing entries. However, we can recompute the hash value from other contents of the structure so we don't need to store it. This brings the size of tcp_tap_conn down to 64 bytes again, which means it will fit in a single cacheline on common machines. This change also removes a non-obvious constraint that the hash table have less than twice TCP_MAX_CONNS buckets, because of the way TCP_HASH_BUCKET_BITS was constructed. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Unify the IN_EPOLL flagDavid Gibson2022-11-251-10/+10
| | | | | | | | | | | | There is very little common between the tcp_tap_conn and tcp_splice_conn structures. However, both do have an IN_EPOLL flag which has the same meaning in each case, though it's stored in a different location. Simplify things slightly by moving this bit into the common header of the two structures. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Partially unify tcp_timer() and tcp_splice_timer()David Gibson2022-11-251-0/+3
| | | | | | | | | | These two functions scan all the non-splced and spliced connections respectively and perform timed updates on them. Avoid scanning the now unified table twice, by having tcp_timer scan it once calling the relevant per-connection function for each one. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Unify tcp_defer_handler and tcp_splice_defer_handler()David Gibson2022-11-251-0/+1
| | | | | | | | | | | These two functions each step through non-spliced and spliced connections respectively and clean up entries for closed connections. To avoid scanning the connection table twice, we merge these into a single function which scans the unified table and performs the appropriate sort of cleanup action on each one. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Unify spliced and non-spliced connection tablesDavid Gibson2022-11-251-0/+6
| | | | | | | | | | | | | | | | | | | | | | | Currently spliced and non-spliced connections are stored in completely separate tables, so there are completely independent limits on the number of spliced and non-spliced connections. This is a bit counter-intuitive. More importantly, the fact that the tables are separate prevents us from unifying some other logic between the two cases. So, merge these two tables into one, using the 'c.spliced' common field to distinguish between them when necessary. For now we keep a common limit of 128k connections, whether they're spliced or non-spliced, which means we save memory overall. If necessary we could increase this to a 256k or higher total, which would cost memory but give some more flexibility. For now, the code paths which need to step through all extant connections are still separate for the two cases, just skipping over entries which aren't for them. We'll improve that in later patches. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Add connection union typeDavid Gibson2022-11-251-0/+30
| | | | | | | | | | | | | | | | Currently, the tables for spliced and non-spliced connections are entirely separate, with different types in different arrays. We want to unify them. As a first step, create a union type which can represent either a spliced or non-spliced connection. For them to be distinguishable, the individual types need to have a common header added, with a bit indicating which type this structure is. This comes at the cost of increasing the size of tcp_tap_conn to over one (64 byte) cacheline. This isn't ideal, but it makes things simpler for now and we'll re-optimize this later. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tcp: Move connection state structures into a shared headerDavid Gibson2022-11-251-0/+168
Currently spliced and non-spliced connections use completely independent tracking structures. We want to unify these, so as a preliminary step move the definitions for both variants into a new tcp_conn.h header, shared by tcp.c and tcp_splice.c. This requires renaming some #defines with the same name but different meanings between the two cases. In the process we correct some places that are slightly out of sync between the comments and the code for various event bit names. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>