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* pasta: correctly exit when execvp() failsPaul Holzinger2023-02-121-1/+1
| | | | | | | | | | | | | By default clone() will create a child that does not send SIGCHLD when the child exits. The caller has to specifiy the SIGNAL it should get in the flag bitmask. see clone(2) under "The child termination signal" This fixes the problem where pasta would not exit when the execvp() call failed, i.e. when the command does not exists. Signed-off-by: Paul Holzinger <pholzing@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pasta: do not leak netlink sock into childPaul Holzinger2023-02-121-2/+2
| | | | | | | | | | | | | | When spawning a child command with pasta command... pasta should not leak fds that it opened. Only the fds that were already open should be given to the child. Run `pasta --config-net -- ls -l /proc/self/fd` from a terminal where only stdin/out/err are open. The fd 3 was opend by ls to read the /proc/self/fd dir. But fd 5 is the netlink socket that was opend in pasta. To prevent such a leak we will open the socket with SOCK_CLOEXEC. Signed-off-by: Paul Holzinger <pholzing@redhat.com> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* Make assertions actually usefulDavid Gibson2023-02-127-20/+32
| | | | | | | | | | | | | | | | | | 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>
* tap: Send frames after the first one in tap_send_frames_pasta()Stefano Brivio2023-02-121-1/+2
| | | | | | | ...instead of repeatedly sending out the first one in iov. Fixes: e21ee41ac35a ("tcp: Combine two parts of pasta tap send path together") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pasta: Wait for tap to be set up before spawning commandStefano Brivio2023-02-123-1/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adapted from a patch by Paul Holzinger: when pasta spawns a command, operating without a pre-existing user and network namespace, it needs to wait for the tap device to be configured and its handler ready, before the command is actually executed. Otherwise, something like: pasta --config-net nslookup passt.top usually fails as the nslookup command is issued before the network interface is ready. We can't adopt a simpler approach based on SIGSTOP and SIGCONT here: the child runs in a separate PID namespace, so it can't send SIGSTOP to itself as the kernel sees the child as init process and blocks the delivery of the signal. We could send SIGSTOP from the parent, but this wouldn't avoid the possible condition where the child isn't ready to wait for it when the parent sends it, also raised by Paul -- and SIGSTOP can't be blocked, so it can never be pending. Use SIGUSR1 instead: mask it before clone(), so that the child starts with it blocked, and can safely wait for it. Once the parent is ready, it sends SIGUSR1 to the child. If SIGUSR1 is sent before the child is waiting for it, the kernel will queue it for us, because it's blocked. Reported-by: Paul Holzinger <pholzing@redhat.com> Fixes: 1392bc5ca002 ("Allow pasta to take a command to execute") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Use tap_send_frames()David Gibson2023-01-234-166/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To send frames on the tap interface, the UDP uses a fairly complicated two level batching. First multiple frames are gathered into a single "message" for the qemu stream socket, then multiple messages are send with sendmmsg(). We now have tap_send_frames() which already deals with sending a number of frames, including batching and handling partial sends. Use that to considerably simplify things. This does make a couple of behavioural changes: * We used to split messages to keep them under 32kiB (except when a single frame was longer than that). The comments claim this is needed to stop qemu from closing the connection, but we don't have any equivalent logic for TCP. I wasn't able to reproduce the problem with this series, although it was apparently easy to reproduce earlier. My suspicion is that there was never an inherent need to keep messages small, however with larger messages (and default kernel buffer sizes) the chances of needing more than one resend for partial send()s is greatly increased. We used not to correctly handle that case of multiple resends, but now we do. * Previously when we got a partial send on UDP, we would resend the remainder of the entire "message", including multiple frames. The common code now only resends the remainder of a single frame, simply dropping any frames which weren't even partially sent. This is what TCP always did and is probably a better idea for UDP too. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* tap: Improve handling of partial frame sendsDavid Gibson2023-01-231-13/+36
| | | | | | | | | | | | | | | | | | | In passt mode, when writing frames to the qemu socket, we might get a short send. If we ignored this and carried on, the qemu socket would get out of sync, because the bytes we actually sent wouldn't correspond to the length header we already sent. tap_send_frames_passt() handles that by doing a a blocking send to complete the message, but it has a few flaws: * We only attempt to resend once: although it's unlikely in practice, nothing prevents the blocking send() from also being short * We print a debug error if send() returns non-zero.. but send() returns the number of bytes sent, so we actually want it to return the length of the remaining data. Correct those flaws and also be a bit more thorough about reporting problems here. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Use abstracted tap headerDavid Gibson2023-01-232-62/+24
| | | | | | | | | Update the UDP 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>
* tap: Use different io vector bases depending on tap typeDavid Gibson2023-01-232-5/+6
| | | | | | | | | | | | | Currently tap_send_frames() expects the frames it is given to include the vnet_len field, even in pasta mode which doesn't use it (although it need not be initialized in that case). To match, tap_iov_base() and tap_iov_len() construct the frame in that way. This will inconvenience future changes, so alter things to set the buffers to include just the frame needed by the tap backend type. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> 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>
* tap: Add "tap headers" abstractionDavid Gibson2023-01-232-0/+66
| | | | | | | | | | | | | | | | Currently both the TCP and UDP code need to deal in various places with the details of the L2 headers, and also the tap-specific "vnet_len" header. This makes abstracting the tap interface to new backends (e.g. vhost-user or tun) more difficult. To improve this abstraction, create a new 'tap_hdr' structure which represents both L2 (always Ethernet at the moment, but might be vary in future) and any additional tap specific headers (such as the qemu socket's vnet_len field). Provide helper functions and macros to initialize, update and use it. 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 Gibson2023-01-233-15/+8
| | | | | | | | | 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 Gibson2023-01-232-23/+16
| | | | | | | | | | 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>
* util: Introduce hton*_constant() in place of #ifdefsDavid Gibson2023-01-232-63/+24
| | | | | | | | | | | We have several places where we have fairly ugly #ifdefs on __BYTE_ORDER where we need network order values in a constant expression (so we can't use htons() or htonl()). We can do this more cleanly by using a single __BYTE_ORDER ifdef to define htons_constant() and htonl_constant() macros, then using those in all the other places. 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 Gibson2023-01-233-81/+89
| | | | | | | | | | 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>
* tcp: Combine two parts of passt tap send path togetherDavid Gibson2023-01-231-8/+12
| | | | | | | | | | | tcp_l2_buf_flush() open codes the "primary" send of message to the passt tap interface, but calls tcp_l2_buf_flush_part() to handle the case of a short send. Combine these two passt-specific operations into tcp_l2_buf_flush_passt() which is a little cleaner and will enable furrther cleanups. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pcap: Replace pcapm() with pcap_multiple()David Gibson2023-01-233-11/+12
| | | | | | | | | | | | | | | | | | pcapm() captures multiple frames from a msghdr, however the only thing it cares about in the msghdr is the list of buffers, where it assumes there is one frame to capture per buffer. That's what we want for its single caller but it's not the only obvious choice here (one frame per msghdr would arguably make more sense in isolation). In addition pcapm() has logic that only makes sense in the context of the passt specific path its called from: it skips the first 4 bytes of each buffer, because those have the qemu vnet_len rather than the frame proper. Make this clearer by replacing pcapm() with pcap_multiple() which more explicitly takes one struct iovec per frame, and parameterizes how much of each buffer to skip (i.e. the offset of the frame within the buffer). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* pcap: Introduce pcap_frame() helperDavid Gibson2023-01-231-38/+38
| | | | | | | | | | | | pcap(), pcapm() and pcapmm() duplicate some code, for the actual writing to the capture file. The purpose of pcapm() and pcapmm() not calling pcap() seems to be to avoid repeatedly calling gettimeofday() and to avoid printing errors for every packet in a batch if there's a problem. We can accomplish that while still sharing code by adding a new helper which takes the packet timestamp as a parameter. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Don't use separate sockets to listen for spliced packetsDavid Gibson2023-01-131-40/+13
| | | | | | | | | | | | | | | Currently, when ports are forwarded inbound in pasta mode, we open two sockets for incoming traffic: one listens on the public IP address and will forward packets to the tuntap interface. The other listens on localhost and forwards via "splicing" (resending directly via sockets in the ns). Now that we've improved the logic about whether we "splice" any individual packet, we don't need this. Instead we can have a single socket bound to 0.0.0.0 or ::, marked as able to splice and udp_sock_handler() will deal with each packet as appropriate. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Decide whether to "splice" per datagram rather than per socketDavid Gibson2023-01-132-20/+34
| | | | | | | | | | | | | | | | | | | | | | | | Currently we have special sockets for receiving datagrams from locahost which can use the optimized "splice" path rather than going across the tap interface. We want to loosen this so that sockets can receive sockets that will be forwarded by both the spliced and non-spliced paths. To do this, we alter the meaning of the @splice bit in the reference to mean that packets receieved on this socket *can* be spliced, not that they *will* be spliced. They'll only actually be spliced if they come from 127.0.0.1 or ::1. We can't (for now) remove the splice bit entirely, unlike with TCP. Our gateway mapping means that if the ns initiates communication to the gw address, we'll translate that to target 127.0.0.1 on the host side. Reply packets will therefore have source address 127.0.0.1 when received on the host, but these need to go via the tap path where that will be translated back to the gateway address. We need the @splice bit to distinguish that case from packets going from localhost to a port mapped explicitly with -u which should be spliced. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Unify udp_sock_handler_splice() with udp_sock_handler()David Gibson2023-01-131-60/+34
| | | | | | | | | | | | | | These two functions now have a very similar structure, and their first part (calling recvmmsg()) is functionally identical. So, merge the two functions into one. This does have the side effect of meaning we no longer receive multiple packets at once for splice (we already didn't for tap). This does hurt throughput for small spliced packets, but improves it for large spliced packets and tap packets. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Pre-populate msg_names with local addressDavid Gibson2023-01-132-22/+25
| | | | | | | | | | | udp_splice_namebuf is now used only for spliced sending, and so it is only ever populated with the localhost address, either IPv4 or IPv6. So, replace the awkward initialization in udp_sock_handler_splice() with statically initialized versions for IPv4 and IPv6. We then just need to update the port number in udp_sock_handler_splice(). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Don't handle tap receive batch size calculation within a #defineDavid Gibson2023-01-131-3/+6
| | | | | | | | | | | | | | | UDP_MAX_FRAMES gives the maximum number of datagrams we'll ever handle as a batch for sizing our buffers and control structures. The subtly different UDP_TAP_FRAMES gives the maximum number of datagrams we'll actually try to receive at once for tap packets in the current configuration. This depends on the mode, meaning that the macro has a non-obvious dependency on the usual 'c' context variable being available. We only use it in one place, so it makes more sense to open code this. Add an explanatory comment while we're there. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Split receive from preparation and send in udp_sock_handler()David Gibson2023-01-131-27/+52
| | | | | | | | | | | The receive part of udp_sock_handler() and udp_sock_handler_splice() is now almost identical. In preparation for merging that, split the receive part of udp_sock_handler() from the part preparing and sending the frames for sending on the tap interface. The latter goes into a new udp_tap_send() function. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Split sending to passt tap interface into separate functionDavid Gibson2023-01-131-58/+72
| | | | | | | | | | | | | | The last part of udp_sock_handler() does the actual sending of frames to the tap interface. For pasta that's just a call to udp_tap_send_pasta() but for passt, it's moderately complex and open coded. For symmetry, move the passt send path into its own function, udp_tap_send_passt(). This will make it easier to abstract the tap interface in future (e.g. when we want to add vhost-user). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Move sending pasta tap frames to the end of udp_sock_handler()David Gibson2023-01-131-19/+42
| | | | | | | | | | | | | | udp_sock_handler() has a surprising difference in flow between pasta and passt mode: For pasta we send each frame to the tap interface as we prepare it. For passt, though, we prepare all the frames, then send them with a single sendmmsg(). Alter the pasta path to also prepare all the frames, then send them at the end. We already have a suitable data structure for the passt case. This will make it easier to abstract out the tap backend difference in future. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* test/perf/pasta_tcp: Add host to namespace cases for traffic via tapStefano Brivio2023-01-051-0/+57
| | | | | | | | | | Similarly to UDP cases, these were missing as it wasn't clear, when the other tests were introduced, if using the global address of a namespace, from the host, should have resulted in connections being routed via the tap interface. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* tcp: Explicitly check option length field values in tcp_opt_get()Stefano Brivio2023-01-051-0/+4
| | | | | | | | | | | | | Reported by Coverity (CWE-606, Untrusted loop bound), and actually harmless because we'll exit the option-scanning loop if the remaining length is not enough for a new option, instead of reading past the header. In any case, it looks like a good idea to explicitly check for reasonable values of option lengths. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* test/perf/pasta_udp: Add host to namespace cases for traffic via tapStefano Brivio2023-01-051-0/+37
| | | | | | | | | | | | | | These were missing as it wasn't clear, when the other tests were introduced, if using the global address of a namespace, from the host, should have resulted in traffic being routed via the tap interface (as opposed to the loopback interface). We now clarified that's actually the case. Use same values and thresholds as the tests for loopback traffic, as throughput figures currently indicate there isn't much difference. Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
* udp: Factor out control structure management from udp_sock_fill_data_v[46]David Gibson2022-12-061-68/+50
| | | | | | | | | | | | | | | | | | | | The main purpose of udp_sock_fill_data_v[46]() is to construct the IP, UDP and other headers we'll need to forward data onto the tap interface. In addition they update the control structures (iovec and mmsghdr) we'll need to send the messages, and in the case of pasta actually sends it. This leads the control structure management and the send itself awkwardly split between udp_sock_fill_data_v[46]() and their caller udp_sock_handler(). In addition, this tail part of udp_sock_fill_datav[46] is essentially common between the IPv4 and IPv6 versions, apart from which control array we're working on. Clean this up by reducing these functions to just construct the headers and renaming them to udp_update_hdr[46]() accordingly. The control structure updates are now all in the caller, and common for IPv4 and IPv6. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Preadjust udp[46]_l2_iov_tap[].iov_base for pasta modeDavid Gibson2022-12-061-18/+18
| | | | | | | | | | | | | | | | | Currently, we always populate udp[46]_l2_iov_tap[].iov_base with the very start of the header buffers, including space for the qemu vnet_len tag suitable for passt mode. That's ok because we don't actually use these iovecs for pasta mode. However, we do know the mode in udp_sock[46]_iov_init() so adjust these to the beginning of the headers we'll actually need for the mode: including the vnet_len tag for passt, but excluding it for pasta. This allows a slightly nicer way to locate the right buffer to send in the pasta case, and will allow some additional cleanups later. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Better factor IPv4 and IPv6 paths in udp_sock_handler()David Gibson2022-12-061-22/+18
| | | | | | | | | | | | | | | Apart from which mh array they're operating on the recvmmsg() calls in udp_sock_handler() are identical between the IPv4 and IPv6 paths, as are some of the control structure updates. By using some local variables to refer to the IP version specific control arrays, make some more logic common between the IPv4 and IPv6 paths. As well as slightly reducing the code size, this makes it less likely that we'll accidentally use the IPv4 arrays in the IPv6 path or vice versa as we did in a recently fixed bug. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Fix incorrect use of IPv6 mh buffers in IPv4 pathDavid Gibson2022-12-061-4/+4
| | | | | | | | | | | | | | | | | | | | | | udp_sock_handler() incorrectly uses udp6_l2_mh_tap[] on the IPv4 path. In fact this is harmless because this assignment is redundant (the 0th entry msg_hdr will always point to the 0th iov entry for both IPv4 and IPv6 and won't change). There is also an incorrect usage of udp6_l2_mh_tap[] in udp_sock_fill_data_v4. This one can cause real problems, because we'll use stale iov_len values if we send multiple messages to the qemu socket. Most of the time that will be relatively harmless - we're likely to either drop UDP packets, or send duplicates. However, if the stale iov_len we use ends up referencing an uninitialized buffer we could desynchronize the qemu stream socket. Correct both these bugs. The UDP6 path appears to be correct, but it does have some comments that incorrectly reference the IPv4 versions, so fix those as well. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Correct splice forwarding when receiving from multiple sourcesDavid Gibson2022-12-061-5/+14
| | | | | | | | | | | | | | | | | | | | | | | | | udp_sock_handler_splice() reads a whole batch of datagrams at once with recvmmsg(). It then forwards them all via a single socket on the other side, based on the source port. However, it's entirely possible that the datagrams in the set have different source ports, and thus ought to be forwarded via different sockets on the destination side. In fact this situation arises with the iperf -P4 throughput tests in our own test suite. AFAICT we only get away with this because iperf3 is strictly one way and doesn't send reply packets which would be misdirected because of the incorrect source ports. Alter udp_sock_handler_splice() to split the packets it receives into batches with the same source address and send each batch with a separate sendmmsg(). For now we only look for already contiguous batches, which means that if there are multiple active flows interleaved this is likely to degenerate to batches of size 1. For now this is the simplest way to correct the behaviour and we can try to optimize later. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Split send half of udp_sock_handler_splice() from the receive halfDavid Gibson2022-12-061-23/+53
| | | | | | | | | Move the part of udp_sock_handler_splice() concerned with sending out the datagrams into a new udp_splice_sendfrom() helper. This will make later cleanups easier. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Unify buffers for tap and splice pathsDavid Gibson2022-12-061-40/+31
| | | | | | | | | | | | | | | | | | | | | | We maintain a set of buffers for UDP packets to be forwarded via the tap interface in udp[46]_l2_buf. We then have a separate set of buffers for packets to be "spliced" in udp_splice_buf[]. However, we only use one of these at a time, so we can share the buffer space. For the receiving splice packets we can not only re-use the data buffers but also the udp[46]_l2_iov_sock and udp[46]_l2_mh_sock control structures. For sending the splice packets we keep the same data buffers, but we need specific control structures. We create udp[46]_iov_splice - we can't reuse udp_l2_iov_sock[] because we need to write iov_len as we're writing spliced packets, but the tap path expects iov_len to remain the same (it only uses it for receive). Likewise we create udp[46]_mh_splice with the mmsghdr structures for sending spliced packets. As well as needing to reference different iovs, these need to all reference udp_splice_namebuf instead of individual msg_name fields for each slot. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Add helper to extract port from a sockaddr_in or sockaddr_in6David Gibson2022-12-061-12/+14
| | | | | | | | | | udp_sock_handler_splice() has a somewhat clunky if to extract the port from a socket address which could be either IPv4 or IPv6. Future changes are going to make this even more clunky, so introduce a helper function to do this extraction. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Make UDP_SPLICE_FRAMES and UDP_TAP_FRAMES_MEM the same thingDavid Gibson2022-12-061-28/+27
| | | | | | | | | | These two constants have the same value, and there's not a lot of reason they'd ever need to be different. Future changes will further integrate the spliced and "tap" paths so that these need to be the same. So, merge them into UDP_MAX_FRAMES. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Simplify udp_sock_handler_spliceDavid Gibson2022-12-061-32/+15
| | | | | | | | Previous cleanups mean that we can now rework some complex ifs in udp_sock_handler_splice() into a simpler set. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Update UDP "connection" timestamps in both directionsDavid Gibson2022-12-061-2/+17
| | | | | | | | | | | | | | | | | | | | | A UDP pseudo-connection between port A in the init namespace and port B in the pasta guest namespace involves two sockets: udp_splice_init[v6][B] and udp_splice_ns[v6][A]. The socket which originated this "connection" will be permanent but the other one will be closed on a timeout. When we get a packet from the originating socket, we update the timeout on the other socket, but we don't do the same when we get a reply packet from the other socket. However any activity on the "connection" probably indicates that it's still in use. Without this we could incorrectly time out a "connection" if it's using a protocol which involves a single initiating packet, but which then gets continuing replies from the target. Correct this by updating the timeout on both sockets for a packet in either direction. This also updates the timestamps for the permanent originating sockets which is unnecessary, but harmless. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Don't explicitly track originating socket for spliced "connections"David Gibson2022-12-061-61/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | When we look up udp_splice_to_ns[][].orig_sock in udp_sock_handler_splice() we're finding the socket on which the originating packet for the "connection" was received on. However, we don't specifically need this socket to be the originating one - we just need one that's bound to the the source port of this reply packet in the init namespace. We can look this up in udp_splice_to_init[v6][src].target_sock, whose defining characteristic is exactly that. The same applies with init and ns swapped. In practice, of course, the port we locate this way will always be the originating port, since we couldn't have started this "connection" if it wasn't. Change this, and we no longer need the @orig_sock field at all. That leaves just @target_sock which we rename to simply @sock. The whole udp_splice_flow structure now more represents a single bound port than a "flow" per se, so rename and recomment it accordingly. Likewise the udp_splice_to_{ns,init} names are now misleading, since the ports in those maps are used in both directions. Rename them to udp_splice_{ns,init} indicating the location where the described socket is bound. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Re-use fixed bound sockets for packet forwarding when possibleDavid Gibson2022-12-061-9/+13
| | | | | | | | | | | | | | | | | | | | | | When we look up udp_splice_to_ns[v6][src].target_sock in udp_sock_handler_splice, all we really require of the socket is that it be bound to port src in the pasta guest namespace. Similarly for udp_splice_to_init but bound in the init namespace. Usually these sockets are created temporarily by udp_splice_connect() and cleaned up by udp_timer(). However, depending on the -u and -U options its possible we have a permanent socket bound to the relevant port created by udp_sock_init(). If such a socket exists, we could use it instead of creating a temporary one. In fact we *must* use it, because we'll fail trying to bind() a temporary one to the same port. So allow this, store permanently bound sockets into udp_splice_to_{ns,init} in udp_sock_init(). These won't get incorrectly removed by the timer because we don't put a corresponding entry in the udp_act[] structure which directs the timer what to clean up. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Don't create double sockets for -U portDavid Gibson2022-12-061-18/+14
| | | | | | | | | | | | | | | | | | For each IP version udp_socket() has 3 possible calls to sock_l4(). One is for the "non-spliced" bound socket in the init namespace, one for the "spliced" bound socket in the init namespace and one for the "spliced" bound socket in the pasta namespace. However when this is called to create a socket in the pasta namspeace there is a logic error which causes it to take the path for the init side spliced socket as well as the ns socket. This essentially tries to create two identical sockets on the ns side. Unsurprisingly the second bind() call fails according to strace. Correct this to only attempt to open one socket within the ns. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
* udp: Split splice field in udp_epoll_ref into (mostly) independent bitsDavid Gibson2022-12-063-35/+35
| | | | | | | | | | | | | | | | | | | The @splice field in union udp_epoll_ref can have a number of values for different types of "spliced" packet flows. Split it into several single bit fields with more or less independent meanings. The new @splice field is just a boolean indicating whether the socket is associated with a spliced flow, making it identical to the @splice fiend in tcp_epoll_ref. The new bit @orig, indicates whether this is a socket which can originate new udp packet flows (created with -u or -U) or a socket created on the fly to handle reply socket. @ns indicates whether the socket lives in the init namespace or the pasta namespace. Making these bits more orthogonal to each other will simplify some future cleanups. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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