January 2026 - dev

[PATCH] apparmor: Allow reading TCP RTO sysctl parameters
by Stefano Brivio 08 Jan '26

08 Jan '26

From: Martin Pitt <mpitt(a)redhat.com> Since commits 3dde0e07804e ("tcp: Update data retransmission timeout") and 1a834879a2f7 ("tcp: Clamp the retry timeout") from 2025-12-02, passt reads additional TCP-related sysctl parameters from /proc to configure retransmission timeout behavior: - /proc/sys/net/ipv4/tcp_syn_retries - /proc/sys/net/ipv4/tcp_syn_linear_timeouts - /proc/sys/net/ipv4/tcp_rto_max_ms These are read by tcp_get_rto_params() during initialization. Adjust the AppArmor profile accordingly. Link: https://bugzilla.redhat.com/show_bug.cgi?id=2426863 Link: https://github.com/cockpit-project/bots/pull/8568 Fixes: 3dde0e07804e ("tcp: Update data retransmission timeout") Fixes: 1a834879a2f7 ("tcp: Clamp the retry timeout") Signed-off-by: Martin Pitt <mpitt(a)redhat.com> [sbrivio: Minor formatting change, changed commit references] Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com> --- Martin, I took the liberty to add a newline around the lines you're adding so that we need a single comment and everything is aligned. I also changed the format of commit references to what we typically use, which is inspired by the preferred format for kernel submissions, I used this one-liner: git show -s --abbrev=12 --pretty=format:"Fixes: %h (\"%s\")" "${SHA}" which actually belongs to CONTRIBUTING.md, cf. page 1241 of my to-do book. contrib/apparmor/abstractions/passt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/contrib/apparmor/abstractions/passt b/contrib/apparmor/abstractions/passt index 43fd63f..25b2ea8 100644 --- a/contrib/apparmor/abstractions/passt +++ b/contrib/apparmor/abstractions/passt @@ -36,6 +36,10 @@ @{PROC}/sys/net/ipv4/ip_local_port_range r, # fwd_probe_ephemeral() + @{PROC}/sys/net/ipv4/tcp_syn_retries r, # tcp_get_rto_params(), tcp.c + @{PROC}/sys/net/ipv4/tcp_syn_linear_timeouts r, + @{PROC}/sys/net/ipv4/tcp_rto_max_ms r, + network netlink raw, # nl_sock_init_do(), netlink.c network inet stream, # tcp.c -- 2.43.0

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[PATCH v3 01/14] inany: Extend inany_ntop() to treat NULL as a fully unspecified address
by David Gibson 08 Jan '26

08 Jan '26

In a number of places we're using a convention that a NULL inany represents a dual-stack unspecified address, that is one which includes both 0.0.0.0 and ::. Extend inany_ntop() to handle that convention, representing it as "*". Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- inany.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/inany.c b/inany.c index 7680439d..87a4d8b6 100644 --- a/inany.c +++ b/inany.c @@ -22,7 +22,7 @@ const union inany_addr inany_loopback4 = INANY_INIT4(IN4ADDR_LOOPBACK_INIT); const union inany_addr inany_any4 = INANY_INIT4(IN4ADDR_ANY_INIT); /** inany_ntop - Convert an IPv[46] address to text format - * @src: IPv[46] address + * @src: IPv[46] address (NULL for unspecified) * @dst: output buffer, minimum INANY_ADDRSTRLEN bytes * @size: size of buffer at @dst * @@ -30,9 +30,12 @@ const union inany_addr inany_any4 = INANY_INIT4(IN4ADDR_ANY_INIT); */ const char *inany_ntop(const union inany_addr *src, char *dst, socklen_t size) { - const struct in_addr *v4 = inany_v4(src); + const struct in_addr *v4; + + if (!src) + return strncpy(dst, "*", size); - if (v4) + if ((v4 = inany_v4(src))) return inet_ntop(AF_INET, v4, dst, size); return inet_ntop(AF_INET6, &src->a6, dst, size); -- 2.52.0

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[PATCH] udp_flow: remove unneeded epoll_ref indirection
by Laurent Vivier 08 Jan '26

08 Jan '26

The fref union was used to convert flow_sidx_t to uint32_t for assignment to ref.data. This is unnecessary since epoll_ref already contains a flowside member of type flow_sidx_t, so we can assign directly. This aligns with how icmp.c and other callers assign flow_sidx_t to epoll_ref. Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- udp_flow.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/udp_flow.c b/udp_flow.c index 8907f2f72741..0ba788060db7 100644 --- a/udp_flow.c +++ b/udp_flow.c @@ -74,10 +74,6 @@ static int udp_flow_sock(const struct ctx *c, { const struct flowside *side = &uflow->f.side[sidei]; uint8_t pif = uflow->f.pif[sidei]; - union { - flow_sidx_t sidx; - uint32_t data; - } fref = { .sidx = FLOW_SIDX(uflow, sidei) }; union epoll_ref ref; int rc; int s; @@ -89,7 +85,7 @@ static int udp_flow_sock(const struct ctx *c, } ref.type = EPOLL_TYPE_UDP; - ref.data = fref.data; + ref.flowside = FLOW_SIDX(uflow, sidei); ref.fd = s; flow_epollid_set(&uflow->f, EPOLLFD_ID_DEFAULT); -- 2.52.0

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[PATCH v2 0/5] Fixes for Fedora 43
by David Gibson 07 Jan '26

07 Jan '26

While away, I updated my laptop to Fedora 43. Naturally a bunch of things in the passt tests broke. First there were the usual breakages due to a new static checker version (also one real bug). Then several other problems. Changes in v2: * Trivial whitespace fix from Laurent * Used more natural array iteration in 2/5 (suggested by Laurent) * Added Laurent's R-b tags David Gibson (5): util: Be more defensive about buffer overruns in read_file() migrate: Don't use terminator element for versions[] array treewide: Don't rely on terminator records in ip[46].dns arrays test: Handle Operating System Command escapes in terminal output test: Include sshd-auth in mbuto guest image conf.c | 8 ++++++-- dhcp.c | 4 +++- dhcpv6.c | 4 +++- migrate.c | 8 ++++---- ndp.c | 4 +++- passt.h | 4 ++-- test/lib/term | 4 ++-- test/passt.mbuto | 6 ++++++ util.c | 2 +- 9 files changed, 30 insertions(+), 14 deletions(-) -- 2.52.0

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[PATCH v3 1/5] util: Be more defensive about buffer overruns in read_file()
by David Gibson 07 Jan '26

07 Jan '26

clang-21.1.7 complains about read_file(), thinking that total_read might come to exceed buf_size, leading to an out of bounds access at the end of the function. In fact, the semantics of read()'s return mean this can't ever happen. But we already have to check for the total_read == buf_size case, so it's basically free to change it to >= and suppress the error. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> Reviewed-by: Laurent Vivier <lvivier(a)redhat.com> --- util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/util.c b/util.c index 27303950..a48f727c 100644 --- a/util.c +++ b/util.c @@ -715,7 +715,7 @@ static ssize_t read_file(const char *path, char *buf, size_t buf_size) close(fd); - if (total_read == buf_size) { + if (total_read >= buf_size) { buf[buf_size - 1] = '\0'; return -ENOBUFS; } -- 2.52.0

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[PATCH] udp_vu: Discard datagrams when RX virtqueue is not usable
by Laurent Vivier 07 Jan '26

07 Jan '26

During vhost-user device initialization, UDP datagrams may arrive on listening sockets before the guest has enabled the RX virtqueue. When this happens, udp_vu_sock_recv() returns 0 without consuming the datagram from the socket. The caller, udp_sock_fwd(), uses a while loop with udp_peek_addr() to process pending datagrams. Since the datagram remains in the socket buffer, udp_peek_addr() keeps returning data available, causing a busy loop with 100% CPU usage. Add an early check for virtqueue readiness in udp_vu_sock_to_tap(), mirroring tcp_vu_data_from_sock(). When the queue is not enabled or not started, explicitly discard the datagram with recvmsg() and return. The caller will drain remaining datagrams through repeated calls. Fixes: 28997fcb29b5 ("vhost-user: add vhost-user") Link: https://bugs.passt.top/show_bug.cgi?id=185 Signed-off-by: Laurent Vivier <lvivier(a)redhat.com> --- udp_vu.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/udp_vu.c b/udp_vu.c index c30dcf97698f..67f4ee619bfb 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -211,6 +211,17 @@ void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx) struct vu_virtq *vq = &vdev->vq[VHOST_USER_RX_QUEUE]; int i; + if (!vu_queue_enabled(vq) || !vu_queue_started(vq)) { + struct msghdr msg = { 0 }; + + debug("Got UDP packet, but RX virtqueue not usable yet"); + + if (recvmsg(s, &msg, MSG_DONTWAIT) < 0) + debug_perror("Failed to discard datagram"); + + return; + } + for (i = 0; i < n; i++) { ssize_t dlen; int iov_used; -- 2.52.0

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[PATCH v2 2/5] migrate: Don't use terminator element for versions[] array
by David Gibson 07 Jan '26

07 Jan '26

When scanning the versions[] array we use a dummy entry to detect when we're finished. Use ARRAY_SIZE() instead, which is almost as easy, a little safer, and doesn't cause clang-tidy 21.1.7 to complain. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> Reviewed-by: Laurent Vivier <lvivier(a)redhat.com> --- migrate.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/migrate.c b/migrate.c index 48d63a07..a70ea7b7 100644 --- a/migrate.c +++ b/migrate.c @@ -123,7 +123,6 @@ static const struct migrate_version versions[] = { * MSS and omitted timestamps, which meant it usually wouldn't work. * Therefore we don't attempt to support compatibility with it. */ - { 0 }, }; /* Current encoding version */ @@ -180,6 +179,7 @@ static const struct migrate_version *migrate_target_read_header(int fd) const struct migrate_version *v; struct migrate_header h; uint32_t id, compat_id; + unsigned i; if (read_all_buf(fd, &h, sizeof(h))) return NULL; @@ -196,9 +196,9 @@ static const struct migrate_version *migrate_target_read_header(int fd) return NULL; } - for (v = versions; v->id; v++) - if (v->id <= id && v->id >= compat_id) - return v; + for (i = 0; i < ARRAY_SIZE(versions); v++) + if (versions[i].id <= id && versions[i].id >= compat_id) + return &versions[i]; errno = ENOTSUP; err("Unsupported device state version: %u", id); -- 2.52.0

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[PATCH v2 1/5] util: Be more defensive about buffer overruns in read_file()
by David Gibson 07 Jan '26

07 Jan '26

clang-21.1.7 complains about read_file(), thinking that total_read might come to exceed buf_size, leading to an out of bounds access at the end of the function. In fact, the semantics of read()'s return mean this can't ever happen. But we already have to check for the total_read == buf_size case, so it's basically free to change it to >= and suppress the error. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> Reviewed-by: Laurent Vivier <lvivier(a)redhat.com> --- util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/util.c b/util.c index 27303950..a48f727c 100644 --- a/util.c +++ b/util.c @@ -715,7 +715,7 @@ static ssize_t read_file(const char *path, char *buf, size_t buf_size) close(fd); - if (total_read == buf_size) { + if (total_read >= buf_size) { buf[buf_size - 1] = '\0'; return -ENOBUFS; } -- 2.52.0

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[PATCH 0/5] Fixes for Fedora 43 (or other bitrot)
by David Gibson 07 Jan '26

07 Jan '26

While away, I updated my laptop to Fedora 43. Naturally a bunch of things in the passt tests broke. First there were the usual breakages due to a new static checker version (also one real bug). Then several other problems. David Gibson (5): util: Be more defensive about buffer overruns in read_file() migrate: Don't use terminator element for versions[] array treewide: Don't rely on terminator records in ip[46].dns arrays test: Handle Operating System Command escapes in terminal output test: Include sshd-auth in mbuto guest image conf.c | 8 ++++++-- dhcp.c | 4 +++- dhcpv6.c | 4 +++- migrate.c | 3 +-- ndp.c | 4 +++- passt.h | 4 ++-- test/lib/term | 4 ++-- test/passt.mbuto | 6 ++++++ util.c | 2 +- 9 files changed, 27 insertions(+), 12 deletions(-) -- 2.52.0

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[PATCH 2/2] fwd: Minor cleanup to fwd_nat_from_splice()
by David Gibson 06 Jan '26

06 Jan '26

The order we do things in this function is slightly odd, and we have a redundant assignment to tgt->oport. Remove that, and re-order for clarity. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- fwd.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/fwd.c b/fwd.c index 9b701ad0..961c533f 100644 --- a/fwd.c +++ b/fwd.c @@ -660,13 +660,15 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto, return PIF_NONE; } + /* Preserve the src & dest (loopback) addresses */ + tgt->oaddr = ini->eaddr; tgt->eaddr = ini->oaddr; - /* Preserve the specific loopback address used, but let the kernel pick - * a source port on the target side - */ - tgt->oaddr = ini->eaddr; + /* Let the kernel pick a host side source port */ tgt->oport = 0; + if (proto == IPPROTO_UDP) + /* But for UDP preserve the source port */ + tgt->oport = ini->eport; tgt->eport = ini->oport; if (proto == IPPROTO_TCP) @@ -674,12 +676,6 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto, else if (proto == IPPROTO_UDP) tgt->eport += c->udp.fwd_out.delta[tgt->eport]; - /* Let the kernel pick a host side source port */ - tgt->oport = 0; - if (proto == IPPROTO_UDP) - /* But for UDP preserve the source port */ - tgt->oport = ini->eport; - return PIF_HOST; } -- 2.52.0

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