October 2025 - dev

[PATCH v3 0/6] Test and linter fixups
by David Gibson 08 Oct '25

08 Oct '25

Before starting to convert testcases to use tunbridge, I wanted to add linting for the Python test scripts. While doing that I discovered a new crop of cppcheck and clang-tidy false positives, and a Makefile bug. Here's a batch of fixes. I didn't manage to get through the whole testsuite with this. I keep getting hangs on rampstream_out, which I *think* are unrelated. v3: * Delete mypy's cache on make clean v2: * Actually understood why exetool was being deleted, and fixed it properly. David Gibson (6): clang-tidy: Suppress redundant expression warning cppcheck: Suppress the suppression of a suppression cppcheck: Suppress a buggy cppcheck warning cppcheck: Suppress variable scope warnings in dhcpv6() test: Don't delete exetool on make clean test: Add linting of Python test scripts dhcpv6.c | 8 ++++++++ linux_dep.h | 2 +- tcp.c | 5 +++++ test/Makefile | 20 ++++++++++++++++---- test/build/build.py | 5 +++-- test/build/static_checkers.sh | 6 +++++- vhost_user.c | 1 + 7 files changed, 39 insertions(+), 8 deletions(-) -- 2.51.0

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[PATCH] isolation: keep CAP_DAC_OVERRIDE initially
by Cole Robinson 08 Oct '25

08 Oct '25

Reproducer that I'd expect to work $ cd $HOME $ sudo passt --runas $UID --socket foo.sock Failed to bind UNIX domain socket: Permission denied A more practical example is for libguestfs apps when run as user=root. + libguestfs connects to libvirt qemu:///system + libvirt qemu:///system defaults to user=qemu. + chowns passt runtime dir to user=qemu + libguestfs instead requests the VM run as user=root + patches in progress but we are blocked by this issue + passt is launched as root, but can't open socket in passt dir. Obviously libvirt needs improvements too. But it seems like this is a defect as well. Signed-off-by: Cole Robinson <crobinso(a)redhat.com> --- isolation.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/isolation.c b/isolation.c index bbcd23b..b25f349 100644 --- a/isolation.c +++ b/isolation.c @@ -188,6 +188,9 @@ void isolate_initial(int argc, char **argv) * We have to keep CAP_SETUID and CAP_SETGID at this stage, so * that we can switch user away from root. * + * CAP_DAC_OVERRIDE may be required for socket setup when combined + * with --runas. + * * We have to keep some capabilities for the --netns-only case: * - CAP_SYS_ADMIN, so that we can setns() to the netns. * - Keep CAP_NET_ADMIN, so that we can configure interfaces @@ -198,7 +201,7 @@ void isolate_initial(int argc, char **argv) * isolate_prefork(). */ keep = BIT(CAP_NET_BIND_SERVICE) | BIT(CAP_SETUID) | BIT(CAP_SETGID) | - BIT(CAP_SYS_ADMIN) | BIT(CAP_NET_ADMIN); + BIT(CAP_SYS_ADMIN) | BIT(CAP_NET_ADMIN) | BIT(CAP_DAC_OVERRIDE); /* Since Linux 5.12, if we want to update /proc/self/uid_map to create * a mapping from UID 0, which only happens with pasta spawning a child -- 2.51.0

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[PATCH v2 0/6] Refactor epoll handling in preparation for multithreading
by Laurent Vivier 07 Oct '25

07 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 epollfd field in flow_common. This serves dual purposes: tracking registration status (EPOLLFD_INVALID = not registered) and identifying the owning epoll instance. The epollfd field is 8 bits, limiting values to 0-254 (255 = EPOLLFD_INVALID). 5. Apply this pattern consistently across all protocol handlers (TCP, ICMP, UDP), storing the managing epollfd in each flow's common structure. These changes make epoll 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 Laurent Vivier (6): 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 epollfd in flow_common icmp: Use epollfd from flow_common structure udp: Use epollfd from flow_common structure Makefile | 22 +++++++++++----------- epoll_ctl.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ epoll_ctl.h | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ flow.c | 36 +++++++++++++++++++++++++++++------- flow.h | 10 +++++++++- icmp.c | 23 +++++++++++++++-------- passt.c | 2 +- passt.h | 34 ---------------------------------- pasta.c | 7 +++---- pif.c | 32 +++++++++++++++++++++++++------- repair.c | 14 +++++--------- tap.c | 15 +++++---------- tcp.c | 38 +++++++++++++++++++------------------- tcp_conn.h | 8 +------- tcp_splice.c | 25 ++++++++++++------------- udp.c | 2 +- udp_flow.c | 23 +++++++++++++++++++---- util.c | 28 ++-------------------------- util.h | 6 ++++-- vhost_user.c | 14 +++++--------- vu_common.c | 2 +- 21 files changed, 263 insertions(+), 174 deletions(-) create mode 100644 epoll_ctl.c create mode 100644 epoll_ctl.h -- 2.50.1

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[PATCH 0/3] RFC: Preview of tunbridge based tests
by David Gibson 02 Oct '25

02 Oct '25

Here's a preliminary cut at some exeter+tunbridge based test cases. Specifically, this converts the pasta NDP tests from the existing framework. This is pretty unpolished at this stage, and obviously doesn't cover much. At this stage I'm looking less for detailed review and more for first impressions both of how the code looks for writing tests and how the logs appear when running. I think both have a lot of room for improvement, so I'd like to start incorporating feedback ASAP, hence this early version. David Gibson (3): test: Prepare for tunbridge based tests test: Add some missing quoting in exeter runner test: Re-implement pasta NDP tests using tunbridge & exeter test/.gitignore | 2 ++ test/Makefile | 19 ++++++++------ test/lib/exeter | 4 +-- test/pasta/dhcp | 5 ++++ test/pasta/ndp.py | 59 ++++++++++++++++++++++++++++++++++++++++++ test/run | 8 +++--- test/smoke/smoke.py | 26 +++++++++++++++++++ test/tasst/__init__.py | 14 ++++++++++ test/tasst/pasta.py | 40 ++++++++++++++++++++++++++++ 9 files changed, 164 insertions(+), 13 deletions(-) create mode 100755 test/pasta/ndp.py create mode 100755 test/smoke/smoke.py create mode 100644 test/tasst/__init__.py create mode 100644 test/tasst/pasta.py -- 2.51.0

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[PATCH 2/3] test: Add some missing quoting in exeter runner
by David Gibson 02 Oct '25

02 Oct '25

exeter() quoted ${__testid}, but in some places we use it there's an extra level of shell, which needs another layer of quoting. This breaks if testids include ';', which is quite common in exeter tests created as a composition/pipeline of two functions. Add the required extra quoting. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- test/lib/exeter | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/test/lib/exeter b/test/lib/exeter index 3b19beaa..530c6909 100644 --- a/test/lib/exeter +++ b/test/lib/exeter @@ -47,9 +47,9 @@ exeter() { [ ${CI} -eq 1 ] && video_link "${1}" for __testid in $($EXETOOL list -- "$@"); do - __desc="$($EXETOOL desc -- "$@" -- ${__testid})" + __desc="$($EXETOOL desc -- "$@" -- "${__testid}")" status_test_start "${__desc}" - context_run host "$@" "${__testid}" && status_test_ok || status_test_fail + context_run host "$* '${__testid}'" && status_test_ok || status_test_fail done cd .. -- 2.51.0

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[PATCH v3 4/6] cppcheck: Suppress variable scope warnings in dhcpv6()
by David Gibson 02 Oct '25

02 Oct '25

At least some cppcheck versions (2.18.3 for me) complain that the _storage variables in dhcpv6() could be reduced in scope. That's not actually the case, because although we don't reference the variables, we may touch their memory via pointers after the blocks in question. There's no reasonable way for cppcheck to determine that, though, so suppress its warnings. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- dhcpv6.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/dhcpv6.c b/dhcpv6.c index c1a27aba..e4df0db5 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -550,10 +550,18 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, { const struct opt_server_id *server_id = NULL; const struct opt_hdr *client_id = NULL; + /* The _storage variables can't be local to the blocks they're used in, + * because IOV_*_HEADER() may return pointers to them which are + * dereferenced afterwards. Since we don't have Rust-like lifetime + * tracking, cppcheck can't reasonably determine that, so we must + * suppress its warnings. */ + /* cppcheck-suppress [variableScope,unmatchedSuppression] */ struct opt_server_id server_id_storage; struct iov_tail opt, client_id_base; const struct opt_ia_na *ia = NULL; + /* cppcheck-suppress [variableScope,unmatchedSuppression] */ struct opt_hdr client_id_storage; + /* cppcheck-suppress [variableScope,unmatchedSuppression] */ struct opt_ia_na ia_storage; const struct in6_addr *src; struct msg_hdr mh_storage; -- 2.51.0

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[PATCH v3 2/6] cppcheck: Suppress the suppression of a suppression
by David Gibson 02 Oct '25

02 Oct '25

Apparently cppcheck 2.18.3 no longer trips the funcArgNamesDifferent warning on our (re-)definition of close_range(). So instead we get an unmatchedSuppression warning. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- linux_dep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux_dep.h b/linux_dep.h index 1d9e1669..89e590c8 100644 --- a/linux_dep.h +++ b/linux_dep.h @@ -142,7 +142,7 @@ struct tcp_info_linux { #endif __attribute__ ((weak)) -/* cppcheck-suppress funcArgNamesDifferent */ +/* cppcheck-suppress [funcArgNamesDifferent,unmatchedSuppression] */ int close_range(unsigned int first, unsigned int last, int flags) { return syscall(SYS_close_range, first, last, flags); } -- 2.51.0

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[PATCH v2 0/6] Test and linter fixups
by David Gibson 02 Oct '25

02 Oct '25

Before starting to convert testcases to use tunbridge, I wanted to add linting for the Python test scripts. While doing that I discovered a new crop of cppcheck and clang-tidy false positives, and a Makefile bug. Here's a batch of fixes. I didn't manage to get through the whole testsuite with this. I keep getting hangs on rampstream_out, which I *think* are unrelated. v2: * Actually understood why exetool was being deleted, and fixed it properly. David Gibson (6): test: Add linting of Python test scripts clang-tidy: Suppress redundant expression warning cppcheck: Suppress the suppression of a suppression cppcheck: Suppress a buggy cppcheck warning cppcheck: Suppress variable scope warnings in dhcpv6() test: Don't delete exetool on make clean dhcpv6.c | 8 ++++++++ linux_dep.h | 2 +- tcp.c | 5 +++++ test/Makefile | 19 +++++++++++++++---- test/build/build.py | 5 +++-- test/build/static_checkers.sh | 6 +++++- vhost_user.c | 1 + 7 files changed, 38 insertions(+), 8 deletions(-) -- 2.51.0

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[PATCH v2 3/6] cppcheck: Suppress the suppression of a suppression
by David Gibson 02 Oct '25

02 Oct '25

Apparently cppcheck 2.18.3 no longer trips the funcArgNamesDifferent warning on our (re-)definition of close_range(). So instead we get an unmatchedSuppression warning. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- linux_dep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux_dep.h b/linux_dep.h index 1d9e1669..89e590c8 100644 --- a/linux_dep.h +++ b/linux_dep.h @@ -142,7 +142,7 @@ struct tcp_info_linux { #endif __attribute__ ((weak)) -/* cppcheck-suppress funcArgNamesDifferent */ +/* cppcheck-suppress [funcArgNamesDifferent,unmatchedSuppression] */ int close_range(unsigned int first, unsigned int last, int flags) { return syscall(SYS_close_range, first, last, flags); } -- 2.51.0

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[PATCH v2 1/6] test: Add linting of Python test scripts
by David Gibson 02 Oct '25

02 Oct '25

We currently have one test moved to the new exeter based framwork written in Python. We plan to add many more, so add linting (flake8) and type checking (mypy) of those scripts. This can be invoked manually with "make flake8" or "make mypy" in test/, and is also added to the static checkers test set. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- test/Makefile | 14 +++++++++++++- test/build/build.py | 5 +++-- test/build/static_checkers.sh | 6 +++++- 3 files changed, 21 insertions(+), 4 deletions(-) diff --git a/test/Makefile b/test/Makefile index 49388276..61ccb075 100644 --- a/test/Makefile +++ b/test/Makefile @@ -8,6 +8,8 @@ BATS = bats -j $(shell nproc) EXETOOL = exeter/exetool/exetool WGET = wget -c +FLAKE8 = flake8 +MYPY = mypy --strict DEBIAN_IMGS = debian-8.11.0-openstack-amd64.qcow2 \ debian-10-nocloud-amd64.qcow2 \ @@ -65,11 +67,15 @@ LOCAL_ASSETS = mbuto.img mbuto.mem.img podman/bin/podman QEMU_EFI.fd \ ASSETS = $(DOWNLOAD_ASSETS) $(LOCAL_ASSETS) EXETER_PYPATH = exeter/py3 +EXETER_PYTHON = build/build.py EXETER_BATS = smoke/smoke.sh.bats \ - build/build.py.bats build/static_checkers.sh.bats + $(EXETER_PYTHON:%=%.bats) build/static_checkers.sh.bats BATS_FILES = $(EXETER_BATS) \ podman/test/system/505-networking-pasta.bats +# Python test code (for linters) +PYPKGS = $(EXETER_PYTHON) + CFLAGS = -Wall -Werror -Wextra -pedantic -std=c99 assets: $(ASSETS) @@ -128,6 +134,12 @@ medium.bin: big.bin: dd if=/dev/urandom bs=1M count=10 of=$@ +flake8: pull-exeter + PYTHONPATH=$(EXETER_PYPATH) $(FLAKE8) $(PYPKGS) + +mypy: pull-exeter + PYTHONPATH=$(EXETER_PYPATH) $(MYPY) $(PYPKGS) + $(EXETER_BATS): %.bats: % $(EXETOOL) PYTHONPATH=$(EXETER_PYPATH) $(EXETOOL) bats -- $< > $@ diff --git a/test/build/build.py b/test/build/build.py index e49287c9..e3de8305 100755 --- a/test/build/build.py +++ b/test/build/build.py @@ -18,11 +18,12 @@ import os from pathlib import Path import subprocess import tempfile -from typing import Iterable, Iterator +from typing import Iterator import exeter -def sh(cmd): + +def sh(cmd: str) -> None: """Run given command in a shell""" subprocess.run(cmd, shell=True) diff --git a/test/build/static_checkers.sh b/test/build/static_checkers.sh index 42806e79..228b99ae 100755 --- a/test/build/static_checkers.sh +++ b/test/build/static_checkers.sh @@ -21,6 +21,10 @@ exeter_set_description cppcheck "passt sources pass cppcheck" exeter_register clang_tidy make -C .. clang-tidy exeter_set_description clang_tidy "passt sources pass clang-tidy" -exeter_main "$@" +exeter_register flake8 make flake8 +exeter_set_description flake8 "passt tests in Python pass flake8" +exeter_register mypy make mypy +exeter_set_description mypy "passt tests in Python pass mypy --strict" +exeter_main "$@" -- 2.51.0

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