- dev - passt

[PATCH] tcp: Properly remove sockets from epoll loop when connection is closed
by David Gibson 13 Nov '25

13 Nov '25

Most of the handling for closing a TCP connectin is in conn_event_do() when it receives a 'CLOSED' event. We specifically check for this case and, correctly, remove the connection from the flow hash table. However, we also bypass the call tp tcp_epoll_ctl() which is not correct. By skipping tcp_epoll_ctl() we skip it's specific handling of the CLOSED event, which includes removing the TCP socket from epoll. If we somehow get an event on such a stale socket, we'll get a stale flow reference. That flow slot might have been re-used, leading to to a crash in conn_at_sidx(). Fixes: b86afe3559c0 ("tcp: Don't defer hash table removal") Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- tcp.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/tcp.c b/tcp.c index e91c0cf5..3202d338 100644 --- a/tcp.c +++ b/tcp.c @@ -694,12 +694,13 @@ void conn_event_do(const struct ctx *c, struct tcp_tap_conn *conn, flow_dbg(conn, "%s", num == -1 ? "CLOSED" : tcp_event_str[num]); - if (event == CLOSED) - flow_hash_remove(c, TAP_SIDX(conn)); - else if ((event == TAP_FIN_RCVD) && !(conn->events & SOCK_FIN_RCVD)) + if ((event == TAP_FIN_RCVD) && !(conn->events & SOCK_FIN_RCVD)) { conn_flag(c, conn, ACTIVE_CLOSE); - else + } else { + if (event == CLOSED) + flow_hash_remove(c, TAP_SIDX(conn)); tcp_epoll_ctl(c, conn); + } if (CONN_HAS(conn, SOCK_FIN_SENT | TAP_FIN_ACKED)) tcp_timer_ctl(conn); -- 2.51.1

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[PATCH v7 0/5] Retry SYNs for inbound connections
by Yumei Huang 10 Nov '25

10 Nov '25

When a client connects, SYN would be sent to guest only once. If the guest is not connected or ready at that time, the connection will be reset in 10s. These patches introduce the SYN retry mechanism using the similar backoff timeout as linux kernel. Also update the data retransmission timeout using the backoff timeout. v7: - Update read_file() and read_file_integer() - Rename tcp_syn_params_init() to tcp_get_rto_params() - Modify the implementation of the timeout assignment - Add a patch to clamp the retry timeout Yumei Huang (5): tcp: Rename "retrans" to "retries" util: Introduce read_file() and read_file_integer() function tcp: Resend SYN for inbound connections tcp: Update data retransmission timeout tcp: Clamp the retry timeout tcp.c | 86 ++++++++++++++++++++++++++++++++++++++++++------------ tcp.h | 6 ++++ tcp_conn.h | 12 ++++---- util.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ util.h | 2 ++ 5 files changed, 168 insertions(+), 24 deletions(-) -- 2.49.0

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Re: [PATCH v2] contrib/selinux: use regex instead of SELinux template
by Stefano Brivio 06 Nov '25

06 Nov '25

On Wed, 05 Nov 2025 03:28:22 -0700 Max Chernoff <git(a)maxchernoff.ca> wrote: > Hi Stefano, > > On Tue, 2025-11-04 at 22:13 +0100, Stefano Brivio wrote: > > Max, thanks for testing and reviewing, I took the liberty to translate > > your comments into Tested-by: and Reviewed-by: tags as they clearly > > seemed to indicate that. > > Ah, thanks for that! I'm still fairly new to the patch-on-a-mailing-list > workflow, so is there something that I should have done differently? We use pretty much the same tags as the Linux kernel does: https://docs.kernel.org/process/submitting-patches.html#using-reported-by-t… (except we only use Link:, not Closes:) which are nice because they're machine-readable, so one could use, say, for instance, a script like: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scr… to Cc: you automatically on a patch if you often reviewed or tested the code or file affected by it. So, here, you could have simply replied with: Reviewed-by: Max Chernoff <git(a)maxchernoff.ca> Tested-by: Max Chernoff <git(a)maxchernoff.ca> to unequivocally state what you did with that submission. Now, passt is small enough that we don't really have much of a use for that at the moment, but it still sounds like a good idea in general, also to future-proof things. It's also small enough that I can add / fix tags as I merge patches without much fuss. And yes, this should also be added to the new CONTRIBUTING.md file, I have a growing list of small items to add and I'll do that in a batch at some point. :) -- Stefano

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Re: [PATCH] contrib/selinux: use regex instead of non-standard bash macro
by Stefano Brivio 05 Nov '25

05 Nov '25

Hi Danish, On Mon, 27 Oct 2025 14:19:14 +0530 Danish Prakash <contact(a)danishpraka.sh> wrote: > On 10/16/25 4:26 PM, Max Chernoff wrote: > > Hi Stefano, > > > > On Thu, 2025-10-16 at 10:21 +0200, Stefano Brivio wrote: > >> On Thu, 16 Oct 2025 13:10:41 +0530 > >> Danish Prakash <contact(a)danishpraka.sh> wrote: > >>> It might be possible to avoid using non-standard bash macro (%USERID), > > > > It's not a Bash macro, it's a SELinux template. This doesn't seem to be > > documented anywhere (which isn't terribly surprising with SELinux), but > > it's defined in this file: > > > > https://github.com/SELinuxProject/selinux/blob/ceb5b221/libsemanage/src/gen… > > Thanks Max, I wasn't aware of it being an SELinux template. > > > > >> I wonder if > >> Max remembers any reason why we couldn't do this in the first place. > > > > The Fedora SELinux policy always uses %{USERID}, and so I copied it from > > there: > > > > $ grep -RnF '%{USERID}' policy/ > > policy/modules/contrib/dbus.fc:29:/run/user/%{USERID}/bus -s gen_context(system_u:object_r:session_dbusd_tmp_t,s0) > > policy/modules/contrib/dbus.fc:30:/run/user/%{USERID}/dbus(/.*)? gen_context(system_u:object_r:session_dbusd_tmp_t,s0) > > policy/modules/contrib/dbus.fc:31:/run/user/%{USERID}/dbus-1(/.*)? gen_context(system_u:object_r:session_dbusd_tmp_t,s0) > > policy/modules/contrib/gnome.fc:25:/run/user/%{USERID}/\.orc(/.*)? gen_context(system_u:object_r:gstreamer_home_t,s0) > > policy/modules/contrib/gnome.fc:26:/run/user/%{USERID}/dconf(/.*)? gen_context(system_u:object_r:config_home_t,s0) > > policy/modules/contrib/gnome.fc:27:/run/user/%{USERID}/keyring.* gen_context(system_u:object_r:gkeyringd_tmp_t,s0) > > policy/modules/kernel/filesystem.fc:17:/run/user/%{USERID}/gvfs -d gen_context(system_u:object_r:fusefs_t,s0) > > policy/modules/kernel/filesystem.fc:18:/run/user/%{USERID}/gvfs/.* <<none>> > > policy/modules/system/userdomain.fc:38:/run/user/%{USERID} -d gen_context(system_u:object_r:user_tmp_t,s0) > > policy/modules/system/userdomain.fc:39:/run/user/%{USERID}/.+ <<none>> > > > > $ grep -RnF '[0-9]+' policy/ | grep -v /dev/ > > policy/modules/contrib/rpm.fc:52:/usr/bin/rhn_check-[0-9]+\.[0-9]+ -- gen_context(system_u:object_r:rpm_exec_t,s0) > > policy/modules/contrib/soundserver.fc:12:/run/yiff-[0-9]+\.pid -- gen_context(system_u:object_r:soundd_var_run_t,s0) > > policy/modules/kernel/devices.if:6958:## Allow read the hfi1_[0-9]+ devices > > > >>> diff --git a/contrib/fedora/passt.spec b/contrib/fedora/passt.spec > >>> index 663289f53d97..d1bcf4a74338 100644 > >>> --- a/contrib/fedora/passt.spec > >>> +++ b/contrib/fedora/passt.spec > >>> [...] > >> > >> At a glance, this looks like a better solution regardless of the > >> reported issue. It sounds too good to be true, though > > > > I agree that it looks like a good solution, which makes me wonder why > > the base SELinux policies don't do it that way. The containers SELinux > > policy appears to do things this way > > > > $ grep -RnF '[0-9]+' > > container_selinux.8:166: /run/user/[0-9]+/gvfs > > $ grep -RnF '%{USERID}'; echo $? > > 1 > > > > so it's probably (?) okay though. > > That's helpful, I guess we can go ahead with this. Stefano, Paul? Sure. But back to my question about the original problem... what was the original problem? :) Could it be something similar to: https://bugzilla.redhat.com/show_bug.cgi?id=2401764 ? In general, there are a bunch of current SELinux issues reported on Fedora/RHEL (and I assume they would be exactly the same on openSUSE/SLES): https://bugzilla.redhat.com/buglist.cgi?bug_status=__open__&columnlist=shor… and I'm trying to find out if this change might fix some of them. Most of those are stuff I didn't investigate yet. -- Stefano

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[RFC PATCH 0/3] Fill exceeding size of vhost-user buffers explicitly
by Stefano Brivio 05 Nov '25

05 Nov '25

While looking for a way to ensure inbound frames are padded to 60 bytes in vhost-user mode, I spotted the issue described in 1/3, which looks a bit too obvious to be true, so I'm sending this as RFC. Am I missing something there, or do we actually need to fix that? Stefano Brivio (3): vu_common: Stick to size of input buffer in vu_send_single() iov: Fix coding style of basic (non-IOV_TAIL) parts iov, vu_common: Make iov_from_buf() fill destination iov entirely iov.c | 116 +++++++++++++++++++++++++++------------------------- iov.h | 4 +- vu_common.c | 22 +++++----- 3 files changed, 74 insertions(+), 68 deletions(-) -- 2.43.0

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[PATCH 0/8] RFC: Cleanups to auto port scanning
by David Gibson 03 Nov '25

03 Nov '25

One of the trickiest parts of implementing the improved forwarding table is integrating it properly with automatic forwarding (-t auto etc.). Here are some preliminary cleanups to the automatic port scanning that will make the job a bit easier. David Gibson (8): icmp: Remove vestiges of ICMP timer tcp, udp, fwd: Run all port scanning from a single timer fwd: Consolidate scans (not rebinds) in fwd.c fwd: Move port exclusion handling from procfs_scan_listen() to callers fwd: Share port scanning logic between init and timer cases fwd: Check forwarding mode in fwd_scan_ports_*() rather than caller fwd: Update all port maps before applying exclusions tcp, udp: Don't exclude ports in {tcp,udp}_port_rebind() fwd.c | 107 ++++++++++++++++++++++++++++++++++++++------------------ fwd.h | 7 ++-- icmp.h | 2 -- passt.c | 8 ++--- tcp.c | 34 +++++++++--------- tcp.h | 3 +- udp.c | 31 ++++------------ udp.h | 4 +-- util.c | 23 ++++++++++++ util.h | 1 + 10 files changed, 129 insertions(+), 91 deletions(-) -- 2.51.0

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[PATCH v2 0/8] Cleanups to auto port scanning
by David Gibson 01 Nov '25

01 Nov '25

One of the trickiest parts of implementing the improved forwarding table is integrating it properly with automatic forwarding (-t auto etc.). Here are some preliminary cleanups to the automatic port scanning that will make the job a bit easier. v2: * Rename bitmap_andc() to bitmap_and_not() (4/8) * Fixed comment formatting error (4/8) * Updated commit message based on further information from Stefano (7,8/8) * All other patches unchanged, except for trivial rebase fixes David Gibson (8): icmp: Remove vestiges of ICMP timer tcp, udp, fwd: Run all port scanning from a single timer fwd: Consolidate scans (not rebinds) in fwd.c fwd: Move port exclusion handling from procfs_scan_listen() to callers fwd: Share port scanning logic between init and timer cases fwd: Check forwarding mode in fwd_scan_ports_*() rather than caller fwd: Update all port maps before applying exclusions tcp, udp: Don't exclude ports in {tcp,udp}_port_rebind() fwd.c | 107 ++++++++++++++++++++++++++++++++++++++------------------ fwd.h | 7 ++-- icmp.h | 2 -- passt.c | 8 ++--- tcp.c | 34 +++++++++--------- tcp.h | 3 +- udp.c | 31 ++++------------ udp.h | 4 +-- util.c | 24 +++++++++++++ util.h | 2 ++ 10 files changed, 131 insertions(+), 91 deletions(-) -- 2.51.0

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[PATCH 3/3] test: Re-implement pasta NDP tests using tunbridge & exeter
by David Gibson 31 Oct '25

31 Oct '25

Convert the pasta NDP tests from shell and our own DSL to Python using the exeter test protocol and tunbridge network simulation library. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- test/Makefile | 2 +- test/pasta/dhcp | 5 ++++ test/pasta/ndp.py | 59 ++++++++++++++++++++++++++++++++++++++++++ test/run | 6 +++-- test/tasst/__init__.py | 4 +++ test/tasst/pasta.py | 40 ++++++++++++++++++++++++++++ 6 files changed, 113 insertions(+), 3 deletions(-) create mode 100755 test/pasta/ndp.py create mode 100644 test/tasst/pasta.py diff --git a/test/Makefile b/test/Makefile index f66c7e7e..95e3d75e 100644 --- a/test/Makefile +++ b/test/Makefile @@ -67,7 +67,7 @@ ASSETS = $(DOWNLOAD_ASSETS) $(LOCAL_ASSETS) EXETER_SH = smoke/smoke.sh build/static_checkers.sh EXETER_PYPATH = exeter/py3:tunbridge/:. -EXETER_PYTHON = smoke/smoke.py build/build.py +EXETER_PYTHON = smoke/smoke.py build/build.py pasta/ndp.py EXETER_BATS = $(EXETER_SH:%=%.bats) $(EXETER_PYTHON:%=%.bats) BATS_FILES = $(EXETER_BATS) \ podman/test/system/505-networking-pasta.bats diff --git a/test/pasta/dhcp b/test/pasta/dhcp index e1c66be6..61279fbf 100644 --- a/test/pasta/dhcp +++ b/test/pasta/dhcp @@ -18,6 +18,11 @@ test Interface name nsout IFNAME ip -j link show | jq -rM '.[] | select(.link_type == "ether").ifname' check [ -n "__IFNAME__" ] +# Bring up the interface +ns ip link set dev __IFNAME__ up +# Wait for SLAAC & DAD to complete +ns while ! ip -j -6 addr show dev __IFNAME__ | jq -e '.[].addr_info.[] | select(.protocol == "kernel_ra")'; do sleep 0.1; done + test DHCP: address ns /sbin/dhclient -4 --no-pid __IFNAME__ nsout ADDR ip -j -4 addr show|jq -rM '.[] | select(.ifname == "__IFNAME__").addr_info[0].local' diff --git a/test/pasta/ndp.py b/test/pasta/ndp.py new file mode 100755 index 00000000..8c7ce31e --- /dev/null +++ b/test/pasta/ndp.py @@ -0,0 +1,59 @@ +#! /usr/bin/env python3 +# +# SPDX-License-Identifier: GPL-2.0-or-later +# +# test/pasta/ndp.py - pasta NDP functionality +# +# Copyright Red Hat +# Author: David Gibson <david(a)gibson.dropbear.id.au> + +import contextlib +import dataclasses +from typing import Iterator + +import exeter +import tunbridge +import tasst + + +(a)dataclasses.dataclass +class UnconfiguredScenario(exeter.Scenario): + """Tests for a pasta instance without --config-net""" + + host: tunbridge.Site + guest: tunbridge.Site + ifname: str + addr6: tunbridge.ip.AddrMask6 + gw6: tunbridge.ip.Addr6 + + @exeter.scenariotest + def test_ifname(self) -> None: + ifs = tunbridge.ip.ifs(self.guest) + exeter.assert_eq(set(ifs), {'lo', self.ifname}) + + @tunbridge.ndp.NdpScenario.subscenario + def test_ndp(self) -> tunbridge.ndp.NdpScenario: + tunbridge.ip.ifup(self.guest, self.ifname) + return tunbridge.ndp.NdpScenario(client=self.guest, + ifname=self.ifname, + network=self.addr6.network, + gateway=self.gw6) + + +(a)UnconfiguredScenario.test +(a)contextlib.contextmanager +def simh_pasta_setup() -> Iterator[UnconfiguredScenario]: + with (tunbridge.sample.simple_host('host') as simh, + tunbridge.sample.isolated('guest', simh.site) as guest): + assert simh.ip6 is not None + assert simh.gw6_ll is not None + with tasst.pasta.pasta(simh.site, guest): + yield UnconfiguredScenario(host=simh.site, + guest=guest, + ifname=simh.ifname, + addr6=simh.ip6, + gw6=simh.gw6_ll) + + +if __name__ == '__main__': + exeter.main() diff --git a/test/run b/test/run index 3872a56e..4f09d767 100755 --- a/test/run +++ b/test/run @@ -43,8 +43,10 @@ KERNEL=${KERNEL:-"/boot/vmlinuz-$(uname -r)"} COMMIT="$(git log --oneline --no-decorate -1)" -# Let exeter tests written in Python find their modules +# Let exeter tests written in Python find their modules and binaries to run export PYTHONPATH=${BASEPATH}/exeter/py3:${BASEPATH}/tunbridge:${BASEPATH} +export PASTA=${PASTA:-${BASEPATH}/../pasta} + . lib/util . lib/context @@ -75,8 +77,8 @@ run() { exeter build/build.py exeter build/static_checkers.sh + exeter pasta/ndp.py setup pasta - test pasta/ndp test pasta/dhcp test pasta/tcp test pasta/udp diff --git a/test/tasst/__init__.py b/test/tasst/__init__.py index fd4fe9a8..f5386b3a 100644 --- a/test/tasst/__init__.py +++ b/test/tasst/__init__.py @@ -8,3 +8,7 @@ # # Copyright Red Hat # Author: David Gibson <david(a)gibson.dropbear.id.au> + +from . import pasta + +__all__ = ['pasta'] diff --git a/test/tasst/pasta.py b/test/tasst/pasta.py new file mode 100644 index 00000000..91f59036 --- /dev/null +++ b/test/tasst/pasta.py @@ -0,0 +1,40 @@ +#! /usr/bin/env python3 +# +# SPDX-License-Identifier: GPL-2.0-or-later +# +# TASST - Test A Simple Socket Transport +# +# test/tasst/pasta.py - Helpers for seeting up pasta instances +# +# Copyright Red Hat +# Author: David Gibson <david(a)gibson.dropbear.id.au> + +import contextlib +import os +from typing import Iterator + +import tunbridge + + +(a)contextlib.contextmanager +def pasta(host: tunbridge.Site, guest: tunbridge.Site, *opts: str) \ + -> Iterator[tunbridge.site.SiteProcess]: + if tunbridge.unshare.parent(guest) is not host: + raise ValueError("pasta guest must be a namespace under host site") + + # This implies guest is a namespace site + assert isinstance(guest, tunbridge.unshare.NsenterSite) + + exe = os.environ['PASTA'] + + with host.tempdir() as piddir: + pidfile = os.path.join(piddir, 'pasta.pid') + cmd = [exe, '-f', '-P', pidfile] + list(opts) + [f'{guest.pid}'] + with host.bg(*cmd, stop=True) as pasta: + # Wait for the PID file to be written + pidstr = None + while not pidstr: + pidstr = host.readfile(pidfile, check=False) + pid = int(pidstr) + print(f'pasta started, host: {host}, guest: {guest}, pid: {pid}') + yield pasta -- 2.51.0

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[PATCH v5 0/7] Refactor epoll handling in preparation for multithreading
by Laurent Vivier 30 Oct '25

30 Oct '25

This series refactors how epoll file descriptors are managed throughout the codebase in preparation for introducing multithreading support. Currently, passt uses a single global epollfd accessed through the context structure. With multithreading, each thread will need its own epollfd managing its subset of flows. The key changes are: 1. Centralize epoll management by extracting helper functions into a new epoll_ctl.c/h module and moving union epoll_ref from passt.h to its more logical location in epoll_ctl.h. 2. Simplify epoll_del() to take the epollfd directly rather than extracting it from the context structure, reducing coupling between epoll operations and the global context. 3. Move epoll registration out of sock_l4_sa() into protocol-specific code, giving callers explicit control over which epoll instance manages each socket. 4. Replace the boolean in_epoll flag in TCP connections with an epollid (epoll identifier) field in flow_common. This serves dual purposes: tracking registration status (EPOLLFD_ID_INVALID = not registered) and identifying which epoll instance manages the flow. An epoll ID to epoll fd mapping allows retrieving the actual epoll file descriptor. The epollid field is 8 bits, limiting values to 0-254 (255 = EPOLLFD_ID_INVALID). 5. Apply this pattern consistently across all protocol handlers (TCP, ICMP, UDP), storing the managing epoll ID in each flow's common structure. 6. Extract the event loop processing logic into a separate passt_worker() function, preparing the structure for future threading where this will become a worker thread callback. These changes make epoll instance ownership explicit in the flow tracking system, enabling flows to be managed by different epoll instances, a prerequisite for per-thread epollfd design in upcoming multithreading work. Changes since v1: - New patch: "epoll_ctl: Extract epoll operations" - centralizes epoll helpers into a dedicated module and relocates union epoll_ref from passt.h to epoll_ctl.h - Changed epollfd type in flow_common from int to 8-bit bitfield to avoid exceeding cacheline size threshold - Added flow_epollfd_valid() helper to check epoll registration status - Added flow_set_epollfd() helper to set the epoll instance for a flow Changes since v2: - Renamed field in flow_common from epollfd to threadnb (thread number) to better reflect that flows are now associated with threads rather than directly with epoll file descriptors - Introduced thread-to-epollfd mapping via threadnb_to_epollfd[] array in flow.c, providing an indirection layer between threads and their epoll instances - Renamed/refactored helper functions: - flow_set_epollfd() -> flow_epollfd_set() - now takes thread number and epollfd parameters - Added flow_epollfd_get() - retrieves the epoll fd for a flow's thread - flow_epollfd_valid() - now checks threadnb instead of epollfd - Updated constants: replaced EPOLLFD_* with FLOW_THREADNB_* equivalents (e.g., EPOLLFD_INVALID -> FLOW_THREADNB_INVALID) - Applied thread-based pattern consistently across TCP, ICMP, and UDP Changes since v3: - Change warn() by err() in epoll_add() - Renamed flow_epollfd_valid() to flow_in_epoll(), flow_epollfd_get() to flow_epollfd(). - Added flow_thread_register() to register an epollfd to a thread number, and called it from main() to register c->epollfd for thread 0 (main loop) - Replaced flow_epollfd_set() by flow_thread_set() to set the thread number of a flow. - Added new patch: "passt: Move main event loop processing into passt_worker()" Changes since v4: - Renamed field in flow_common from threadnb to epollid (epoll identifier) to better reflect the abstraction - flows are associated with an epoll instance identifier rather than specifically a thread number - Renamed mapping array from threadnb_to_epollfd[] to epoll_id_to_fd[] - Renamed/refactored helper functions: - flow_thread_set() -> flow_epollid_set() - sets the epoll ID - flow_thread_register() -> flow_epollid_register() - registers the epollfd for a given epoll ID - Added flow_epollid_clear() - explicitly clears the epoll ID - Updated constants: replaced FLOW_THREADNB_* with EPOLLFD_ID_* equivalents (e.g., FLOW_THREADNB_INVALID -> EPOLLFD_ID_INVALID, FLOW_THREADNB_MAX -> EPOLLFD_ID_MAX) - Added EPOLLFD_ID_DEFAULT constant for the default (main loop) epoll instance - Clarified that EPOLLFD_ID_BITS limits the number of epoll instances, not threads (though initially there will be one epoll instance per thread) Laurent Vivier (7): util: Simplify epoll_del() interface to take epollfd directly epoll_ctl: Extract epoll operations util: Move epoll registration out of sock_l4_sa() tcp, flow: Replace per-connection in_epoll flag with an epollid in flow_common icmp: Use epoll instance management for ICMP flows udp: Use epoll instance management for UDP flows passt: Move main event loop processing into passt_worker() Makefile | 22 +++---- epoll_ctl.c | 45 ++++++++++++++ epoll_ctl.h | 51 ++++++++++++++++ flow.c | 71 +++++++++++++++++++--- flow.h | 15 ++++- icmp.c | 23 +++++--- passt.c | 163 ++++++++++++++++++++++++++++----------------------- passt.h | 34 ----------- pasta.c | 7 +-- pif.c | 32 +++++++--- repair.c | 18 +++--- tap.c | 15 ++--- tcp.c | 46 +++++++++------ tcp_conn.h | 8 +-- tcp_splice.c | 26 ++++---- udp.c | 2 +- udp_flow.c | 23 ++++++-- util.c | 28 +-------- util.h | 6 +- vhost_user.c | 14 ++--- vu_common.c | 2 +- 21 files changed, 403 insertions(+), 248 deletions(-) create mode 100644 epoll_ctl.c create mode 100644 epoll_ctl.h -- 2.51.0

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[PATCH v15 0/9] Use true MAC address of LAN local remote hosts
by Jon Maloy 30 Oct '25

30 Oct '25

Bug #120 asks us to use the true MAC addresses of LAN local remote hosts, since some programs need this information. These commits introduces this for ARP, NDP, UDP, TCP and ICMP. --- v3: Updated according to feedback from Stefano and David: - Made the ARP/NDP lookup call filter out the requested address by itself, qualified by the index if the template interface - Moved the flow specific MAC address from struct flowside to struct flow_common. v4: - Updated according to feedback from David and Stefan - Added a cache table for ARP/NDP table contents v5: - Updated according to feedback from David and Stefan - Added cache table entries to FIFO/LRU queue - New criteria for when to consult ARP/NDP v6: - Simplified and merged mac cache table commits - Other changes after feedback from David. v7: - Fixes in patch #2 based on feedback from David and Stefano. v8: - Redesigned netlink and cache table part to be based on a subscription model. v8: - Small fix to patch #2 so that we cover the case when a MAC addess for a host has changed. - Added a commit where we send a gratuitous ARP/ unsolicitated NA to the guest when a new host is added to the neighbour cache table. v10: - Some fixes after feedback from David Gibson - Reordered: Moved patch #9 to position #3. - Added synchronization step between ARP/NDP table contents and the neigbour table at initialization. This reduces the number of "false" ARP/NDP replies drastically, but not completly. - (Next step could be to scan over the flow table and update affeced entries when we receive a MAC address update.) v11: - Corrected the gratuitous ARP implementation to use the "ARP Announcement" model instead of the "Gratuitous ARP reply" model. v12: - Updated based on feedback from David and Stefano - Added special handling of default GW and loopback addresses. v13: - Updated based on discussion with David and Stefano - Conceptually moved to only considering guest-side visible addresss. A lot of things became simpler and clearer through this change. Thank you, David. - Introduced a 'permanent' flag in the special entries representing addessed mapping to own host and conditionally the guest gw. This flag indicates those entries cannot be altered by possible remote hosts shadowed by these addresses. Suggested by Stefano. - Reordered patch ##4 and 5, since #5 cannot work correctly for NDP unsolicited NA until #4 is in place. - Added a new commit #2 to get later access to the flag no_map_gw. It was wrong to call fwd_neigh_table_init() from inside conf(), it has to be done in main() after random_init() and tap_backend_init(). v14: - Some fixes after feedback from David Gibson, notably - Moved the call to nat_inbound() from fwd.c to netlink.c - Added RFC quotes to explain the format of ARP announce messages. v15: - More fixes, after feedback and discussions. Notably: - Added a secondary lookup in fwd_neigh_mac_get(), so that we respond with the guest GW's MAC address in case the primary lookup fails. - Removed guest_gw IP address as 'blocker' entry in the neighbor table. It is ok to let the host GW MAC address go through if the GW addresses match, and even when they don't we found it isn't needed. - Removed previous patch #2 about no_map_gw, since the change it introduced only was needed by the the functionality we just removed as described above. Jon Maloy (9): netlink: add subscription on changes in NDP/ARP table fwd: Add cache table for ARP/NDP contents arp/ndp: respond with true MAC address of LAN local remote hosts arp/ndp: send ARP announcement / unsolicited NA when neigbour entry added flow: add MAC address of LAN local remote hosts to flow udp: forward external source MAC address through tap interface tcp: forward external source MAC address through tap interface tap: change signature of function tap_push_l2h() icmp: let icmp use mac address from flowside structure arp.c | 59 +++++++++++++- arp.h | 2 + epoll_type.h | 2 + flow.c | 2 + flow.h | 2 + fwd.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++ fwd.h | 7 ++ icmp.c | 8 +- inany.c | 1 + ndp.c | 16 +++- ndp.h | 1 + netlink.c | 208 +++++++++++++++++++++++++++++++++++++++++++++++- netlink.h | 4 + passt.c | 17 ++-- passt.h | 3 +- pasta.c | 2 +- tap.c | 24 +++--- tap.h | 7 +- tcp.c | 20 ++++- tcp.h | 2 +- tcp_buf.c | 37 ++++----- tcp_internal.h | 4 +- tcp_vu.c | 5 +- udp.c | 57 ++++++++----- udp.h | 2 +- util.h | 2 + 26 files changed, 623 insertions(+), 83 deletions(-) -- 2.50.1

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