- dev - passt

[PATCH 3/3] test: Add test for builds with -DNDEBUG
by David Gibson 15 May '26

15 May '26

Since bc872d91765d we omit assert()s if the NDEBUG preprocessor symbol is defined, as is the case with the standard library assert(3). However, none of our tests verify that we can actually build that way. Add an extra test to test/build/build.py tto verify this. Fixes: bc872d91765d ("treewide: Spell ASSERT() as assert()") Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- test/build/build.py | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/test/build/build.py b/test/build/build.py index eeee5acc..59de014a 100755 --- a/test/build/build.py +++ b/test/build/build.py @@ -77,6 +77,20 @@ for bin in BINARIES: exeter.register('make_all', test_make, 'all', BINARIES) +(a)exeter.test +def test_ndebug() -> None: + """Test build with -NDEBUG + + Tests that we can build all binaries with -DNDEBUG (warnings are + expected, though). Doesn't test that they actually work. + """ + + with clone_sources(): + sh('make all CPPFLAGS="-DNDEBUG" CFLAGS="-w"') + for b in BINARIES: + assert Path(b).exists(), f"{b} wasn't made" + + @exeter.test def test_install_uninstall() -> None: """Test `make install` and `make uninstall` -- 2.54.0

1 0

[PATCH] ndp: Suppress Coverity false positive for random()
by Laurent Vivier 14 May '26

14 May '26

Coverity flags the random() call in ndp_timer() with the dont_call checker, warning that it should not be used for security-related applications. This is a false positive: random() is used here to jitter the interval between unsolicited Router Advertisements as required by RFC 4861, to prevent synchronisation between routers on a link. No cryptographic strength is needed. Suppress the warning with an inline Coverity annotation. Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- ndp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/ndp.c b/ndp.c index 1f2bcb0cc7ea..614932ac5829 100644 --- a/ndp.c +++ b/ndp.c @@ -441,6 +441,7 @@ void ndp_timer(const struct ctx *c, const struct timespec *now) * again, it's close enough for our purposes. */ interval = min_rtr_adv_interval + + /* coverity[dont_call:FALSE] */ random() % (max_rtr_adv_interval - min_rtr_adv_interval); if (!next_ra) -- 2.54.0

3 2

[PATCH v3 00/10] vhost-user: Preparatory series for multiple iovec entries per virtqueue element
by Laurent Vivier 14 May '26

14 May '26

Currently, the vhost-user path assumes each virtqueue element contains exactly one iovec entry covering the entire frame. This assumption breaks as some virtio-net drivers (notably iPXE) provide descriptors where the vnet header and the frame payload are in separate buffers, resulting in two iovec entries per virtqueue element. This series refactors the vhost-user data path so that frame lengths, header sizes, and padding are tracked and passed explicitly rather than being derived from iovec sizes. This decoupling is a prerequisite for correctly handling padding of multi-buffer frames. The changes in this series can be split in 3 groups: - New iov helpers (patches 1-2): iov_memset() and iov_memcpy() operate across iovec boundaries. These are needed by the final patch to pad and copy frame data when a frame spans multiple iovec entries. - Structural refactoring (patches 3-5): Move vnethdr setup into vu_flush(), separate virtqueue management from socket I/O in the UDP path, and pass iov arrays explicitly instead of using file-scoped state. These changes make it possible to pass explicit frame lengths through the stack, which is required to pad frames independently of iovec layout. - Explicit length passing throughout the stack (patches 6-10): Thread explicit L4, L2, frame, and data lengths through checksum, pcap, vu_flush(), and tcp_fill_headers(), replacing lengths that were previously derived from iovec sizes. With lengths tracked explicitly, the final patch can centralise Ethernet frame padding into vu_collect() and a new vu_pad() helper that correctly pads frames spanning multiple iovec entries. v3: - csum_udp4()/csum_udp6()/udp_vu_csum receive payload length (dlen) rather than l4len - Add a length parameter to write_remainder() and use it in pcap_frame() v2: - Rename iov_memcopy() to iov_memcpy() and use clearer parameter names - Use clearer code in pcap_frame() - Add braces around bodies in pcap.c and tcp_vu.c for style consistency - Extract l2len variable in tap_add_packet() and tcp_vu_send_flag() to avoid repeating the same expression - Fix indentation alignment of iov_skip_bytes() arguments in tcp_vu_c - Introduce fill_size variable in vu_flush() - Reposition comment for ETH_ZLEN in vu_collect() Laurent Vivier (10): iov: Introduce iov_memset() iov: Add iov_memcpy() to copy data between iovec arrays vu_common: Move vnethdr setup into vu_flush() udp_vu: Move virtqueue management from udp_vu_sock_recv() to its caller udp_vu: Pass iov explicitly to helpers instead of using file-scoped array checksum: Pass explicit L4 length to checksum functions pcap: Pass explicit L2 length to pcap_iov() vu_common: Pass explicit frame length to vu_flush() tcp: Pass explicit data length to tcp_fill_headers() vhost-user: Centralise Ethernet frame padding in vu_collect() and vu_pad() checksum.c | 43 +++++++----- checksum.h | 6 +- iov.c | 78 ++++++++++++++++++++++ iov.h | 5 ++ pcap.c | 28 +++++--- pcap.h | 2 +- tap.c | 10 +-- tcp.c | 14 ++-- tcp_buf.c | 3 +- tcp_internal.h | 2 +- tcp_vu.c | 66 ++++++++++--------- udp.c | 5 +- udp_vu.c | 173 +++++++++++++++++++++++++------------------------ util.c | 31 +++++++-- util.h | 3 +- vu_common.c | 58 ++++++++++------- vu_common.h | 5 +- 17 files changed, 338 insertions(+), 194 deletions(-) -- 2.53.0

3 21

[PATCH v8 0/3] vhost-user,udp: Handle multiple iovec entries per virtqueue element
by Laurent Vivier 13 May '26

13 May '26

Some virtio-net drivers (notably iPXE) provide descriptors where the vnet header and the frame payload are in separate buffers, resulting in two iovec entries per virtqueue element. Currently, the RX (host to guest) path assumes a single iovec per element, which triggers: ASSERTION FAILED in virtqueue_map_desc (virtio.c:403): num_sg < max_num_sg This series reworks the UDP vhost-user receive path to support multiple iovec entries per element, fixing the iPXE crash. This series only addresses the UDP path. TCP vhost-user will be updated to use multi-iov elements in a subsequent series. Based-on: 20260416155721.3807225-1-lvivier(a)redhat.com v8: - Add Reviewed-by from David for 1/3 and 2/3 - Remove VLA to use fixed size (VIRTQUEUE_MAX_SIZE) - Rename udp_frame to datagram - Use sizeof(uh) instead of sizeof(struct udphdr) - Push back uh in memory in udp_vu_csum() v7: - In udp_vu_sock_to_tap(), introduce iov_still_needed variable - Fix iov_tail @data doc comments in udp_vu_prepare()/udp_vu_csum() - Don't rewrap the virtio checksum comment in udp_update_hdr6() - Add NULL check for uh in udp_vu_csum() v6: - Rebased on top of [PATCH 00/10] vhost-user: Preparatory series for multiple iovec entries per virtqueue element v5: - This version doesn't change the padding system regarding v4, it's a complex task that will be addressed in another version - reorder patches and add new patches - remove IOV_PUT_HEADER()/with_header() and introduce IOV_PUSH_HEADER() - don't use the iov_tail to provide the headers to the functions - move vu_set_vnethdr() to vu_flush(), extract vu_queue_notify() - move vu_flush() inside loop in tcp_vu_data_from_sock() to flush data by frame and not by full data length v4: - rebase - replace ASSERT() by assert() v3: - include the series "Decouple iovec management from virtqueues elements" - because of this series, drop: "vu_common: Accept explicit iovec counts in vu_set_element()" "vu_common: Accept explicit iovec count per element in vu_init_elem()" "vu_common: Prepare to use multibuffer with guest RX" "vhost-user,udp: Use 2 iovec entries per element" - drop "vu_common: Pass iov_tail to vu_set_vnethdr()" as the specs insures a buffer is big enough to contain vnet header - introduce "with_header()" and merge "udp: Pass iov_tail to udp_update_hdr4()/udp_update_hdr6()" and "udp_vu: Use iov_tail in udp_vu_prepare()" to use it v2: - add iov_truncate(), iov_memset() - remove iov_tail_truncate() and iov_tail_zero_end() - manage 802.3 minimum frame size Laurent Vivier (3): udp_vu: Allow virtqueue elements with multiple iovec entries iov: Introduce IOV_PUSH_HEADER() macro udp: Pass iov_tail to udp_update_hdr4()/udp_update_hdr6() iov.c | 22 ++++++++++ iov.h | 11 +++++ udp.c | 70 ++++++++++++++++------------- udp_internal.h | 4 +- udp_vu.c | 116 ++++++++++++++++++++++++++----------------------- 5 files changed, 135 insertions(+), 88 deletions(-) -- 2.53.0

3 8

[PATCH v3 04/12] Makefile: Remove unhelpful $(HEADERS) variable
by David Gibson 12 May '26

12 May '26

Confusingly HEADERS is not headers that are shared between our various binaries. Rather it's just the (non generated) headers for passt, plus seccomp.h. This isn't particularly useful, just open code it in the handful of places we need it. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- Makefile | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/Makefile b/Makefile index 88c8a15a..ff442fa2 100644 --- a/Makefile +++ b/Makefile @@ -50,14 +50,13 @@ SRCS = $(PASST_SRCS) $(QRAP_SRCS) $(PASST_REPAIR_SRCS) $(PESTO_SRCS) MANPAGES = passt.1 pasta.1 pesto.1 qrap.1 passt-repair.1 -PASST_HEADERS = arch.h arp.h bitmap.h checksum.h common.h conf.h dhcp.h \ - dhcpv6.h epoll_ctl.h flow.h fwd.h fwd_rule.h flow_table.h icmp.h \ - icmp_flow.h inany.h iov.h ip.h isolation.h lineread.h log.h migrate.h \ - ndp.h netlink.h packet.h passt.h pasta.h pcap.h pesto.h pif.h repair.h \ - serialise.h siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h \ - tcp_splice.h tcp_vu.h udp.h udp_flow.h udp_internal.h udp_vu.h util.h \ - vhost_user.h virtio.h vu_common.h -HEADERS = $(PASST_HEADERS) seccomp.h +PASST_HEADERS = arch.h arp.h bitmap.h checksum.h conf.h dhcp.h dhcpv6.h \ + epoll_ctl.h flow.h fwd.h fwd_rule.h flow_table.h icmp.h icmp_flow.h \ + inany.h iov.h ip.h isolation.h lineread.h log.h migrate.h ndp.h \ + netlink.h packet.h passt.h pasta.h pcap.h pif.h repair.h serialise.h \ + siphash.h tap.h tcp.h tcp_buf.h tcp_conn.h tcp_internal.h tcp_splice.h \ + tcp_vu.h udp.h udp_flow.h udp_internal.h udp_vu.h util.h vhost_user.h \ + virtio.h vu_common.h C := \#include <sys/random.h>\nint main(){int a=getrandom(0, 0, 0);} ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0) @@ -103,10 +102,10 @@ seccomp_pesto.h: seccomp.sh $(PESTO_SRCS) $(BASEBIN): %: $(CC) $(FLAGS) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) $(filter %.c,$^) -o $@ -passt: $(PASST_SRCS) $(HEADERS) +passt: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h passt.avx2: FLAGS += -Ofast -mavx2 -ftree-vectorize -funroll-loops -passt.avx2: $(PASST_SRCS) $(HEADERS) +passt.avx2: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h pasta.avx2 pasta.1 pasta: pasta%: passt% ln -sf $< $@ @@ -202,7 +201,7 @@ CPPCHECK_FLAGS = --std=c11 --error-exitcode=1 --enable=all --force \ --suppress=unusedStructMember \ -D CPPCHECK_6936 -cppcheck: $(PASST_SRCS) $(HEADERS) +cppcheck: $(PASST_SRCS) $(PASST_HEADERS) seccomp.h $(CPPCHECK) $(CPPCHECK_FLAGS) \ $(filter -D%,$(FLAGS) $(CFLAGS) $(CPPFLAGS)) $^ \ $^ -- 2.54.0

1 0

[PATCH v3 03/12] Makefile: Use common binary compilation rule
by David Gibson 12 May '26

12 May '26

Each of our binaries (passt, passt.avx2, qrap and passt-repair) has a separate Make rule instructing how to compile it, but they're all basically identical. Combine these all into a single pattern rule, just using different dependencies and variable overrides where necessary. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- Makefile | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/Makefile b/Makefile index d489a862..88c8a15a 100644 --- a/Makefile +++ b/Makefile @@ -76,9 +76,14 @@ docdir ?= $(datarootdir)/doc/passt mandir ?= $(datarootdir)/man man1dir ?= $(mandir)/man1 -BIN := passt pasta qrap passt-repair pesto +BASEBIN := passt qrap passt-repair pesto ifeq ($(TARGET_ARCH),x86_64) -BIN += passt.avx2 pasta.avx2 +BASEBIN += passt.avx2 +endif + +BIN = $(BASEBIN) pasta +ifeq ($(TARGET_ARCH),x86_64) +BIN += pasta.avx2 endif all: $(BIN) $(MANPAGES) docs @@ -95,27 +100,24 @@ seccomp_repair.h: seccomp.sh $(PASST_REPAIR_SRCS) seccomp_pesto.h: seccomp.sh $(PESTO_SRCS) @ ARCH="$(TARGET_ARCH)" CC="$(CC)" ./seccomp.sh seccomp_pesto.h $(PESTO_SRCS) +$(BASEBIN): %: + $(CC) $(FLAGS) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) $(filter %.c,$^) -o $@ + passt: $(PASST_SRCS) $(HEADERS) - $(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(PASST_SRCS) -o passt $(LDFLAGS) passt.avx2: FLAGS += -Ofast -mavx2 -ftree-vectorize -funroll-loops passt.avx2: $(PASST_SRCS) $(HEADERS) - $(CC) $(filter-out -O2,$(FLAGS)) $(CFLAGS) $(CPPFLAGS) \ - $(PASST_SRCS) -o passt.avx2 $(LDFLAGS) - -passt.avx2: passt pasta.avx2 pasta.1 pasta: pasta%: passt% ln -sf $< $@ +qrap: FLAGS += -DARCH=\"$(TARGET_ARCH)\" qrap: $(QRAP_SRCS) passt.h - $(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) -DARCH=\"$(TARGET_ARCH)\" $(QRAP_SRCS) -o qrap $(LDFLAGS) passt-repair: $(PASST_REPAIR_SRCS) seccomp_repair.h - $(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) $(PASST_REPAIR_SRCS) -o passt-repair $(LDFLAGS) +pesto: FLAGS += -DPESTO pesto: $(PESTO_SRCS) $(PESTO_HEADERS) seccomp_pesto.h - $(CC) $(FLAGS) $(CFLAGS) $(CPPFLAGS) -DPESTO $(PESTO_SRCS) -o pesto $(LDFLAGS) valgrind: EXTRA_SYSCALLS += rt_sigprocmask rt_sigtimedwait rt_sigaction \ rt_sigreturn getpid gettid kill clock_gettime \ -- 2.54.0

1 0

[PATCH 0/8] Fix assorted warnings
by David Gibson 12 May '26

12 May '26

With Fedora 44, I'm hitting a bunch of new warnings, one from the compiler, a few from cppcheck and many from clang-tidy. Fix them. David Gibson (8): netlink: erromsg should be const in nl_status() virtio: Reduce scope of variable conf: Fix not-actually-const parameter to conf_runas() and conf_ugid() clang-tidy: Squash inconsistent brace warnings in foreach macros clang-tidy: Suppress sscanf() warning harder packet, clang-tidy: Packet pool buffers are not NULL treewide: Make some additional variables static clang-tidy: Suppress some new unhelpful new warnings .clang-tidy | 11 +++++++++++ conf.c | 9 +++++---- flow.c | 2 ++ flow_table.h | 8 ++++++-- fwd.c | 3 ++- log.c | 2 +- netlink.c | 3 ++- packet.c | 2 ++ tcp.c | 6 +++--- tcp_buf.c | 4 ++-- virtio.c | 4 ++-- 11 files changed, 38 insertions(+), 16 deletions(-) -- 2.54.0

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passt: new version 2026_05_07.1afd4ed available
by Stefano Brivio 08 May '26

08 May '26

The new version with tag 2026_05_07.1afd4ed includes the following changes: 1afd4ed hooks: Copy static build of pesto and related man page to server 82523bc fedora: Install pesto, its SELinux policy, and the man page from the spec file 5335770 selinux: Add file context and type enforcement for pesto b3b2632 apparmor: Add policy file for pesto 2692ef3 pesto, conf, fwd_rule: Add options and modes to add, delete, clear rules e371d34 fwd_rule: Fix static checkers warnings in fwd_rule_add() 4ff9887 conf, fwd: Allow switching to new rules received from pesto 7c5b1d7 pesto, conf: Send updated rules from pesto back to passt/pasta cbd58d6 pesto: Parse and add new rules from command line fa06768 pesto: Read current ruleset from passt/pasta and optionally display it 24c7ef9 inany: Prepare inany.[ch] for sharing with pesto tool c9f7ed1 ip: Prepare ip.[ch] for sharing with pesto tool ba3047a pesto: Expose list of pifs to pesto and display them f1d893c pesto, conf: Have pesto connect to passt and check versions 8ad7dd4 pesto, log: Share log.h (but not log.c) with pesto tool 02236db pesto: Introduce stub configuration tool 6cf93ed fwd_rule: Fix some format specifiers cbcd428 pif: Limit pif names to 128 bytes 393c87e fwd: Generalise fwd_rules_info() 279b679 fwd_rule: Move conflict checking back within fwd_rule_add() c0e0c2f fwd, conf: Move rule parsing code to fwd_rule.[ch] 21d565d fwd_rule: Move ephemeral port probing to fwd_rule.c 0aeda87 conf, fwd: Stricter rule checking in fwd_rule_add() a458719 tcp: Use SO_MEMINFO for accurate send buffer overhead accounting ec96f01 tcp: Handle errors from tcp_send_flag() a287375 fwd, conf: Add capabilities bits to each forwarding table 2230d5b conf: Don't pass raw commandline argument to conf_ports_spec() 0521f83 conf: Move SO_BINDTODEVICE workaround to conf_ports() 4e09ddf conf: Allow user-specified auto-scanned port forwarding ranges bf7eebc conf: Move "all" handling to port specifier 0a466eb doc: Rework man page description of port specifiers 831857e tcp: Replace send buffer boost with EPOLLOUT monitoring ea5a4bb conf: Rework checking for garbage after a range 42c49e8 conf: Rework stepping through chunks of port specifiers d62a552 conf: Don't be strict about exclusivity of forwarding mode b68cac0 fwd: Improve error handling in fwd_rule_add() 2bffb63 fwd_rule: Move rule conflict checking from fwd_rule_add() to caller 02742fa fwd: Split rule building from rule adding 2093b33 conf: Pass protocol explicitly to conf_ports_range_except() f9d9926 fwd_rule: Move forwarding rule formatting 438b0df fwd: Better split forwarding rule specification from associated sockets dbe0ba1 conf: Permit -[tTuU] all in pasta mode a47b6ac doc: Consolidate -[tu] option descriptions for passt and pasta 189a3c5 conf: Move first pass handling of -[TU] next to handling of -[tu] de8ebc5 conf: Simplify handling of default forwarding mode 4d8aa0a conf: Split parsing of port specifiers from the rest of -[tuTU] parsing 5ac9cf1 tap, tcp, udp: Use rate-limited logging 926f5b4 conf: use a single buffer for print formatting in conf_print() f758d93 log: Add rate-limiting macros for log messages 6dad076 fwd: Split forwarding rule specification from its implementation state 51eaaa7 bitmap: Split bitmap helper functions into their own module 93c3e35 ip: Define a bound for the string returned by ipproto_name() ed187c3 conf: Remove redundant warning when SO_BINDTODEVICE is unavailable 72e7162 conf: Move check for disabled interfaces earlier 9c37a48 conf: Move check for mapping port 0 to caller 66e26b9 conf: Don't bother complaining about overlapping excluded ranges 1f9ee4f fwd, conf: Expose ephemeral ports as bitmap rather than function 35c56c5 fwd: Allow FWD_DUAL_STACK_ANY flag to be passed directly to fwd_rule_add() 559d4dc fwd: Store forwarding tables indexed by (origin) pif 1f974cc fwd: Look up rule index in fwd_sync_one() 0dc9f20 fwd: Move selecting correct scan bitmap into fwd_sync_one() b7a4718 serialise: Add helpers for serialising unsigned integers 8081aa5 serialise: Split functions user for serialisation from util.c 41b0c7b vhost_user: Fix assorted minor cppcheck warnings e2794c7 fwd: Comparing rule can be const 57117e4 conf: runas can be const bc872d9 treewide: Spell ASSERT() as assert() 451fb76 vu_common: Move iovec management into vu_collect() f5391ae vu_handle_tx: Pass actual remaining out_sg capacity to vu_queue_pop() b9d076d virtio: Pass iovec arrays as separate parameters to vu_queue_pop() 47e56fd pif: Remove unused PIF_NAMELEN b5e6ef4 doc: Fix formatting of (DEPRECATED) notes in man page 744d6df Makefile: Use $^ to avoid duplication in static checker rules 1b32bfe conf: Parse all forwarding options at the same time ea239bf conf: Don't defer handling of --dns option ee0e20e fwd: Always open /proc/net{tcp,tcp6,udp,udp6} in pasta mode d460ca3 fwd: Unify TCP and UDP forwarding tables bb2e4dd fwd: Split forwarding table from port scanning state d30e0b7 Fix misnamed field in struct ctx comments 4fa0076 fwd: Don't initialise unused port bitmaps d2438ef tcp: Remove stale description of port_to_tap field 0294fae conf, fwd: Make overall forwarding mode local to conf path 831e983 netlink: Allow NULL to be passed as addr parameter to nl_addr_get (again) 251e676 netlink: Return prefix length for IPv6 addresses in nl_addr_get() 045560c iov: Add iov_truncate() helper and use it in vu handlers 994bb76 tcp: Avoid comparison of expressions with different signedness in RTT_SET() ab77097 tcp: Avoid comparison of expressions with different signedness in tcp_timer_handler() 5766fe8 migrate: Rename v1 address functions to v2 for clarity 71a0d6c vu_common: Always set num_buffers in virtio-net header 685864d clang-tidy: Don't insist on #ifdef over #if defined() 9ee7805 fwd, pif: Replace with pif_sock_l4() with pif_listen() 7d0fe08 tcp: Use flow_foreach_of_type() in tcp_{keepalive,inactivity} adbf5c1 Add missing includes to headers d2f7c21 tcp: Send TCP keepalive segments after a period of tap-side inactivity a681e44 tcp: Extend tcp_send_flag() to send TCP keepalive segments 1820103 tcp: Re-introduce inactivity timeouts based on a clock algorithm e48ce41 tcp: Remove non-working activity timeout mechanism eb3babf tcp_vu, udp_vu: Fix comment headers for header length functions 66e5941 Fix build when HAS_GETRANDOM is undefined 8636c73 tcp_vu, udp_vu: Account for virtio net header in minimum frame size de5b694 tcp_vu: vu_pad() expects l2 length c320191 conf: Support CIDR notation for -a/--address option 02af38d virtio: Introduce VNET_HLEN macro for virtio net header length 812cdb8 tcp: Move tap header update out of tcp_fill_headers() bebafa7 udp: Split activity timeouts for UDP flows 036fb87 checksum: add VSX fast path for POWER8/POWER9 af7b81b migrate: Use forward table information to close() listening sockets 768baf4 tcp, tcp_splice: Check for failures of shutdown(2) 3581ded tcp: Eliminate FIN_TIMEOUT e992b14 tcp: Retransmit FINs like data segments e3f70c0 tcp_splice: Force TCP RST on abnormal close conditions cce94e9 tcp: Properly propagate tap-side RST to socket side 07390d1 doc: Add test program verifying socket RST behaviour 69ce8ee tcp: Add error checking for flow_epoll_set() in tcp_flow_migrate_target() https://passt.top/passt/log/?qt=range&q=2026_01_20.386b5f5..2026_05_07.1afd… Packages: - Alpine Linux: https://pkgs.alpinelinux.org/packages?name=passt - Arch Linux: https://www.archlinux.org/packages/extra/x86_64/passt/ https://archlinuxarm.org/packages/aarch64/passt https://archlinuxarm.org/packages/armv7h/passt - Chimera: https://pkgs.chimera-linux.org/packages?name=passt - Clear Linux: https://github.com/clearlinux-pkgs/passt/ - Copr (CentOS Stream, EPEL, Fedora, Mageia): https://copr.fedorainfracloud.org/coprs/sbrivio/passt/build/10433312/ permanent mirror: https://passt.top/builds/copr/0^20260507.g1afd4ed/ - Debian tracker: https://tracker.debian.org/pkg/passt - Fedora updates: https://bodhi.fedoraproject.org/updates/?packages=passt - Gentoo versions: https://packages.gentoo.org/packages/net-misc/passt - GNU Guix: https://packages.guix.gnu.org/packages/passt/ - Homebrew: https://formulae.brew.sh/formula/passt - NixOS: https://github.com/NixOS/nixpkgs/tree/nixos-unstable/pkgs/by-name/pa/passt - openSUSE: https://software.opensuse.org/package/passt - OpenMandriva: https://github.com/OpenMandrivaAssociation/passt/tree/master - PLD Linux: https://git.pld-linux.org/cgi-bin/gitweb.cgi?p=packages/passt.git - Solus: https://github.com/getsolus/packages/tree/main/packages/p/passt - Ubuntu tracker: https://launchpad.net/ubuntu/+source/passt - Void Linux: https://voidlinux.org/packages/?q=passt - Static builds: - Package for other RPM-based distributions, x86_64 only: https://passt.top/builds/latest/x86_64/passt-g1afd4ed-1.x86_64.rpm - x86_64 static binaries: https://passt.top/builds/latest/x86_64/ - Debian package, from x86_64 static build: https://passt.top/builds/latest/x86_64/passt_1afd4ed-1_all.deb -- Stefano

1 0

[PATCH v3] tcp: Use SO_MEMINFO for accurate send buffer overhead accounting
by Jon Maloy 07 May '26

07 May '26

The TCP window advertised to the guest/container must balance two competing needs: large enough to trigger kernel socket buffer auto-tuning, but not so large that sendmsg() partially fails, causing retransmissions. The current approach uses the difference (SNDBUF_GET() - SIOCOUTQ), but SNDBUF_GET() returns a scaled value that only roughly accounts for per-skb overhead. The clamped_scale approximation doesn't accurately track the actual per-segment overhead, which can lead to both excessive retransmissions and reduced throughput. We now introduce the use of SO_MEMINFO to obtain SK_MEMINFO_SNDBUF and SK_MEMINFO_WMEM_QUEUED from the kernel. The latter is presented in the kernel's own accounting units, i.e. including the sk_buff overhead, and matches exactly what the kernel's own sk_stream_memory_free() function is using. When data is queued and the overhead ratio is observable, we calculate the per-segment overhead as (wmem_queued - sendq) / num_segments, then determine how many additional segments should fit in the remaining buffer space, considering the calculated per-mss overhead. This approach treats segments as discrete quantities, and produces a more accurate estimate of available buffer space than a linear scaling factor does. When the ratio cannot be observed, e.g. because the queue is empty or we are in a transient state, we fall back to the existing clamped_scale calculation (scaling between 100% and 75% of buffer capacity). When SO_MEMINFO succeeds, we also use SK_MEMINFO_SNDBUF directly to set SNDBUF, avoiding a separate SO_SNDBUF getsockopt() call. If SO_MEMINFO is unavailable, we fall back to the pre-existing SNDBUF_GET() - SIOCOUTQ calculation. Link: https://bugs.passt.top/show_bug.cgi?id=138 Link: https://github.com/containers/podman/issues/28219 Signed-off-by: Jon Maloy <jmaloy(a)redhat.com> --- v2: Updated according to feedback from Stefano. Segment-based discrete overhead calculation instead of linear ratio. v3: Addressed Stefano's v2 feedback: - Extracted window calculation into tcp_wnd_from_sndbuf() - Use wmem_queued instead of SIOCOUTQ for fallback and SWS check --- tcp.c | 137 ++++++++++++++++++++++++++++++++++------------------- tcp_conn.h | 2 +- 2 files changed, 89 insertions(+), 50 deletions(-) diff --git a/tcp.c b/tcp.c index 43b8fdb..61160cf 100644 --- a/tcp.c +++ b/tcp.c @@ -295,6 +295,7 @@ #include <arpa/inet.h> #include <linux/sockios.h> +#include <linux/sock_diag.h> #include "checksum.h" #include "util.h" @@ -1017,6 +1018,90 @@ size_t tcp_fill_headers(const struct ctx *c, struct tcp_tap_conn *conn, return MAX(l3len + sizeof(struct ethhdr), ETH_ZLEN); } +/** + * tcp_wnd_from_sndbuf() - Calculate window from available send buffer space + * @s: Socket file descriptor + * @conn: Connection pointer + * @tinfo: tcp_info from kernel + * + * Return: window value to advertise, not scaled + */ +static uint32_t tcp_wnd_from_sndbuf(int s, struct tcp_tap_conn *conn, + const struct tcp_info_linux *tinfo) +{ + uint32_t rtt_ms_ceiling = DIV_ROUND_UP(tinfo->tcpi_rtt, 1000); + uint32_t mem[SK_MEMINFO_VARS]; + socklen_t mem_sl = sizeof(mem); + int mss = MSS_GET(conn); + uint32_t limit, sendq; + + if (ioctl(s, SIOCOUTQ, &sendq)) { + debug_perror("SIOCOUTQ on socket %i, assuming 0", s); + sendq = 0; + } + + if (getsockopt(s, SOL_SOCKET, SO_MEMINFO, &mem, &mem_sl)) { + tcp_get_sndbuf(conn); + + if (sendq > SNDBUF_GET(conn)) /* Due to memory pressure? */ + limit = 0; + else + limit = SNDBUF_GET(conn) - sendq; + } else { + uint32_t sndbuf = mem[SK_MEMINFO_SNDBUF]; + uint32_t wmemq = mem[SK_MEMINFO_WMEM_QUEUED]; + uint32_t scaled = clamped_scale(sndbuf, sndbuf, SNDBUF_SMALL, + SNDBUF_BIG, 75); + + SNDBUF_SET(conn, MIN(INT_MAX, scaled)); + + if (wmemq > sndbuf) { + limit = 0; + } else if (!sendq || !mss || wmemq <= sendq) { + limit = SNDBUF_GET(conn) - wmemq; + } else { + uint32_t used_segs = MAX(sendq / mss, 1); + uint32_t overhead = (wmemq - sendq) / used_segs; + uint32_t remaining = sndbuf - wmemq; + uint32_t avail_segs = remaining / (mss + overhead); + + limit = avail_segs * mss; + } + } + + /* If the sender uses mechanisms to prevent Silly Window + * Syndrome (SWS, described in RFC 813 Section 3) it's critical + * that, should the window ever become less than the MSS, we + * advertise a new value once it increases again to be above it. + * + * The mechanism to avoid SWS in the kernel is, implicitly, + * implemented by Nagle's algorithm (which was proposed after + * RFC 813). + * + * To this end, for simplicity, approximate a window value below + * the MSS to zero, as we already have mechanisms in place to + * force updates after the window becomes zero. This matches the + * suggestion from RFC 813, Section 4. + * + * But don't do this if, either: + * + * - there's nothing in the outbound queue: the size of the + * sending buffer is limiting us, and it won't increase if we + * don't send data, so there's no point in waiting, or + * + * - we haven't sent data in a while (somewhat arbitrarily, ten + * times the RTT), as that might indicate that the receiver + * will only process data in batches that are large enough, + * but we won't send enough to fill one because we're stuck + * with pending data in the outbound queue + */ + if (limit < (uint32_t)MSS_GET(conn) && sendq && + tinfo->tcpi_last_data_sent < rtt_ms_ceiling * 10) + limit = 0; + + return MIN(tinfo->tcpi_snd_wnd, limit); +} + /** * tcp_update_seqack_wnd() - Update ACK sequence and window to guest/tap * @c: Execution context @@ -1124,56 +1209,10 @@ int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn, } } - if ((conn->flags & LOCAL) || tcp_rtt_dst_low(conn)) { + if ((conn->flags & LOCAL) || tcp_rtt_dst_low(conn)) new_wnd_to_tap = tinfo->tcpi_snd_wnd; - } else { - unsigned rtt_ms_ceiling = DIV_ROUND_UP(tinfo->tcpi_rtt, 1000); - uint32_t sendq; - int limit; - - if (ioctl(s, SIOCOUTQ, &sendq)) { - debug_perror("SIOCOUTQ on socket %i, assuming 0", s); - sendq = 0; - } - tcp_get_sndbuf(conn); - - if ((int)sendq > SNDBUF_GET(conn)) /* Due to memory pressure? */ - limit = 0; - else - limit = SNDBUF_GET(conn) - (int)sendq; - - /* If the sender uses mechanisms to prevent Silly Window - * Syndrome (SWS, described in RFC 813 Section 3) it's critical - * that, should the window ever become less than the MSS, we - * advertise a new value once it increases again to be above it. - * - * The mechanism to avoid SWS in the kernel is, implicitly, - * implemented by Nagle's algorithm (which was proposed after - * RFC 813). - * - * To this end, for simplicity, approximate a window value below - * the MSS to zero, as we already have mechanisms in place to - * force updates after the window becomes zero. This matches the - * suggestion from RFC 813, Section 4. - * - * But don't do this if, either: - * - * - there's nothing in the outbound queue: the size of the - * sending buffer is limiting us, and it won't increase if we - * don't send data, so there's no point in waiting, or - * - * - we haven't sent data in a while (somewhat arbitrarily, ten - * times the RTT), as that might indicate that the receiver - * will only process data in batches that are large enough, - * but we won't send enough to fill one because we're stuck - * with pending data in the outbound queue - */ - if (limit < MSS_GET(conn) && sendq && - tinfo->tcpi_last_data_sent < rtt_ms_ceiling * 10) - limit = 0; - - new_wnd_to_tap = MIN((int)tinfo->tcpi_snd_wnd, limit); - } + else + new_wnd_to_tap = tcp_wnd_from_sndbuf(s, conn, tinfo); new_wnd_to_tap = MIN(new_wnd_to_tap, MAX_WINDOW); if (!(conn->events & ESTABLISHED)) diff --git a/tcp_conn.h b/tcp_conn.h index 6985426..9f5bee0 100644 --- a/tcp_conn.h +++ b/tcp_conn.h @@ -98,7 +98,7 @@ struct tcp_tap_conn { #define SNDBUF_BITS 24 unsigned int sndbuf :SNDBUF_BITS; #define SNDBUF_SET(conn, bytes) (conn->sndbuf = ((bytes) >> (32 - SNDBUF_BITS))) -#define SNDBUF_GET(conn) (conn->sndbuf << (32 - SNDBUF_BITS)) +#define SNDBUF_GET(conn) ((uint32_t)(conn->sndbuf << (32 - SNDBUF_BITS))) uint8_t seq_dup_ack_approx; -- 2.52.0

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[PATCH v11 00/23] Dynamic configuration update implementation
by Stefano Brivio 07 May '26

07 May '26

Changes in v11: * Drop debugging left-overs in 10/23, reported by Paul * In 9/23, don't declare argv as const argument for conf_pasta_ns(), because some versions of gcc (perhaps depending on the glibc version?), at least gcc 16.0.1 from Fedora Rawhide, are not happy with that. Suppress the cppcheck warning instead Changes in v10: * For some reason, changes in 9/23 now trigger seemingly unrelated, but valid, cppcheck warnings: fix them directly there * In 19/23, only consider exact matches for rules we're deleting, report an error if there are conflicts that are not exact matches. Further, address (other) comments by Laurent: a typo in the man page, a typo in a comment in fwd_rule_del(), and a serious issue in pesto's main where we would use the "inbound" table for -T / -U Changes in v9: * Rework Makefile changes and solve conflicts so that we can drop the dependency on "Improvements to static checker invocation" * In 8/23, drop the "experimental" note from the man page * In 10/23, switch to protocol version 1, add basil to the magic sauce * In 11/23, initialise struct pesto_pif_info sent by the server (details in commit message) * In 15/23, add description for -s / --show to pesto.1 as well * In 18/23, make comments about redundant checks more verbose * In 19/23, make it clear that tables handled by fwd_rule_del() can't refer to any open socket, add a TODO to fwd_rule_clear() in that sense as well, and use pif_conf_by_name() in pesto to find the table we need to clear * Add 19/23 to 23/23 (LSM policies, packaging stuff) to make pesto ready for shipping Changes in v8: * Implement --add, --delete, and --clear in 19/19, to add forwarding rules instead of replacing tables, delete existing rules, and explicitly clear tables * Address Laurent's comments for 15/19 and 17/19 * In 10/19, instead of passing SOCK_NONBLOCK to accept4(), explicitly set O_NONBLOCK on the listening socket. Using SOCK_NONBLOCK doesn't do what we want, as it results in setting O_NONBLOCK on the new socket rather than on the listening one * Note: 18/19 is left as it is, I didn't address pending comments yet * Note: this doesn't include yet changes for AppArmor and SELinux policies, as well as changes for the template Fedora spec file. I'm still working on them Changes in v7: * Addressed comments from Laurent in 6/18, 8/18, 9/18, 10/18, 11/18, 12/18, 14/18, 15/18 (details in commit messages of single patches, before my Signed-off-by) * Note: this doesn't include yet --add and --delete, I'm still working on that Changes in v6: * Addressed comments from Jon in 10/18, 11/18, 14/18, and 16/18 * Dodged all warnings from static checkers (Coverity Scan and clang-tidy) with changes in 10/18, 11/18, 16/18, and with a new patch, 18/18 * This does *not* include yet the implementation of --add and --delete switches for pesto as I originally intended, I'm rather far from being done with those. At the moment I just have a "mode selection" implementation for command line parsing but merging rules to / removing rules from / clearing the current table is something I barely started (and what I have at the moment isn't really valuable anyway) David wrote: --- Here's the next draft of dynamic configuration updates. This now can successfully update rules, though I've not tested it very extensively. Patches 1..8/18 are preliminary reworks that make sense even without pesto - feel free to apply if you're happy with them. I don't think the rest should be applied yet; we need to at least harden it so passt can't be blocked indefinitely by a client which sends a partial update then waits. Based on my earlier series reworking static checking invocation. TODO: - Don't allow a client which sends a partial configuration then blocks also block passt - Allow pesto to clear existing configuration, not just add - Allow pesto selectively delete existing rules, not just add Changes in v5: * If multiple clients connect at once, they're now blocked until the first one finishes, instead of later ones being discarded Changes in v4: * Merged with remainder of forward rule parsing rework series * Fix some bugs in rule checking pointed out by Laurent * Significantly cleaned up option parsing code * Changed from replacing all existing rules to adding new rules (clear and remove still TBD) * Somewhat simplified protocol (pif names and rules sent in a single pass) * pesto is now allocation free * Fixed commit message and style nits pointed out by Stefano Changes in v3: * Removed already applied ASSERT() rename * Renamed serialisation functions * Incorporated Stefano's extensions, reworked and fixed * Several additional cleanups / preliminary reworks Changes in v2: * Removed already applied cleanups * Reworked assert() patch to handle -DNDEBUG properly * Numerous extra patches: * Factored out serialisation helpers and use them for migration as well * Reworked to allow ip.[ch] and inany.[ch] to be shared with pesto * Reworks to share some forwarding rule datatypes with pesto * Implemented sending pif names and current ruleset to pesto --- David Gibson (17): conf, fwd: Stricter rule checking in fwd_rule_add() fwd_rule: Move ephemeral port probing to fwd_rule.c fwd, conf: Move rule parsing code to fwd_rule.[ch] fwd_rule: Move conflict checking back within fwd_rule_add() fwd: Generalise fwd_rules_info() pif: Limit pif names to 128 bytes fwd_rule: Fix some format specifiers pesto: Introduce stub configuration tool pesto, log: Share log.h (but not log.c) with pesto tool pesto, conf: Have pesto connect to passt and check versions pesto: Expose list of pifs to pesto and display them ip: Prepare ip.[ch] for sharing with pesto tool inany: Prepare inany.[ch] for sharing with pesto tool pesto: Read current ruleset from passt/pasta and optionally display it pesto: Parse and add new rules from command line pesto, conf: Send updated rules from pesto back to passt/pasta conf, fwd: Allow switching to new rules received from pesto Stefano Brivio (6): fwd_rule: Fix static checkers warnings in fwd_rule_add() pesto, conf, fwd_rule: Add options and modes to add, delete, clear rules apparmor: Add policy file for pesto selinux: Add file context and type enforcement for pesto fedora: Install pesto, its SELinux policy, and the man page from the spec file hooks: Copy static build of pesto and related man page to server .gitignore | 2 + Makefile | 35 +- common.h | 116 ++++++ conf.c | 696 ++++++++++++++------------------ conf.h | 2 + contrib/apparmor/usr.bin.pesto | 23 ++ contrib/fedora/passt.spec | 14 +- contrib/selinux/pesto.fc | 11 + contrib/selinux/pesto.te | 95 +++++ epoll_type.h | 4 + flow.c | 4 +- fwd.c | 169 ++------ fwd.h | 41 +- fwd_rule.c | 705 +++++++++++++++++++++++++++++++-- fwd_rule.h | 68 +++- hooks/pre-push | 1 + inany.c | 19 +- inany.h | 17 +- ip.c | 56 +-- ip.h | 4 +- lineread.c | 2 +- log.h | 53 ++- passt.1 | 5 + passt.c | 8 + passt.h | 8 + pasta.c | 4 +- pesto.1 | 275 +++++++++++++ pesto.c | 522 ++++++++++++++++++++++++ pesto.h | 54 +++ pif.c | 2 +- pif.h | 7 +- serialise.c | 7 + serialise.h | 1 + siphash.h | 13 + tap.c | 64 ++- util.h | 110 +---- 36 files changed, 2419 insertions(+), 798 deletions(-) create mode 100644 common.h create mode 100644 contrib/apparmor/usr.bin.pesto create mode 100644 contrib/selinux/pesto.fc create mode 100644 contrib/selinux/pesto.te create mode 100644 pesto.1 create mode 100644 pesto.c create mode 100644 pesto.h -- 2.43.0

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