passt/tcp.c, branch podman23739

flow, treewide: Promote priority of selected flow-linked messages

2026-06-09T02:28:20+00:00

Most of out flow specific log messages are debug level for fear of flooding
the logs, even when they report real error conditions that might be off
significance.

Now that we have the mechanisms for log message rate limiting, we can do
better.  Promote many flow related messages to warning or error level, with
rate limiting.  While we're there add ratelimiting to a handful of existing
warning or error level messages.

They general heuristic is to promote messages that report a failure which
is not something that should be triggered by the guest doing something
weird.  This mostly means failures from socket operations we expect to be
legitimate.

Adding the ratelimiting means plumbing the 'now' timestamp through much
more of the code, hence the large churn.

Signed-off-by: David Gibson

flow: Safer errno handling in flowside_connect() callers

2026-06-09T02:18:40+00:00

flowside_connect() behaves much like connect(2) itself, returning -1 on
error with errno set to the error code.  One of the callers, in
udp_flow_sock(), uses the errno code with flow_dbg_perror() *after* it's
called epoll_del() and close() either of which could clobber errno.

Change flowside_connect() to use the more regular convention for internal
functions: return a negative errno code on error, rather than just -1.
Save it in the callers and use that rather than raw errno to print the
message.

Signed-off-by: David Gibson

flow: Regularise flow specific logging helpers

2026-06-09T02:18:40+00:00

flow.h has a collection of logging helpers that automatically include
information about a specific flow.  Which variants are present are a bit
ad-hoc, based on what we happened to want use (e.g. there are no
LOG_WARNING level versions, at present).  There's also a rather awkward
and only occasionally used flow_log_details_() helper to print additional
log messages with more details of the flow (basically its addresses).
It's particularly awkward to try to combine that with ratelimiting.

Re-organise this to be based around a flow_log__() internal helper, which
has bool parameters to include strerror() / perror information and/or
the extra details.  Add wrapper macros for all combinations of perror,
ratelimiting and DEBUG/WARNING/ERR priorities.

Be a little more consistent about parameter order between the various
functions / macros / wrappers while we're at it.

Signed-off-by: David Gibson

passt, tcp: Inline CALL_PROTO_HANDLER() and merge tcp_timer()

2026-06-04T04:45:09+00:00

Since 260075bde769 ("tcp, udp, fwd: Run all port scanning from a
single timer"), CALL_PROTO_HANDLER() has only one user (tcp), so
inline it at the call site and remove the macro.

Merge tcp_timer() into tcp_defer_handler(), moving the timer interval
check there, matching the pattern used by flow_defer_handler() and
fwd_scan_ports_timer().

The weak declaration and null check for tcp_defer_handler are also
dropped as the function is always defined.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

tcp: Don't leak sockets on error paths

2026-05-27T08:17:42+00:00

tcp_listen_handler() has several error paths that will cancel the creation
of a new flow, after having accept()ed an incoming socket connection.
Coverity pointed out that in those cases we leak the new socket.  Correct
this by properly closing the socket.  Make sure to also set SO_LINGER so
that the peer will get an RST.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

tcp, tcp_splice: Make helper for setting SO_LINGER socket option

2026-05-27T08:17:18+00:00

Both spliced and non-spliced TCP in some cases set the SO_LINGER socket
option in order to to force a TCP RST on a socket side connection.  In each
case we open code the setsockopt() logic.  We're shortly going to add
another place that needs this, so move the setsockopt() and error handling
logic into a shared helper.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

tcp: Encode checksum computation flags in a single parameter

2026-05-26T10:17:10+00:00

tcp_fill_headers() takes a pointer to a previously computed IPv4 header
checksum to avoid recalculating it when the payload length doesn't
change, and a separate bool to skip TCP checksum computation.

Replace both parameters with a single uint32_t csum_flags that encodes:
- IP4_CSUM (bit 31): compute IPv4 header checksum from scratch
- TCP_CSUM (bit 30): compute TCP checksum
- IP4_CMASK (low 16 bits): cached IPv4 header checksum value

When IP4_CSUM is not set, the cached checksum is extracted from the low
16 bits.  This is cleaner than the pointer-based approach, and also
avoids a potential dangling pointer issue: a subsequent patch makes
tcp_fill_headers() access ip4h via with_header(), which scopes it to a
temporary variable, so a pointer to ip4h->check would become invalid
after the with_header() block.

Suggested-by: David Gibson 
Signed-off-by: Laurent Vivier 
Reviewed-by: Jon Maloy 
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

tcp: Pass explicit data length to tcp_fill_headers()

2026-05-19T23:21:51+00:00

tcp_fill_headers() computed the TCP payload length from iov_tail_size(),
but with vhost-user multibuffer frames, the iov_tail will be larger than
the actual data.  Pass the data length explicitly so that IP total
length, pseudo-header, and checksum computations use the correct value.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Reviewed-by: Jon Maloy 
Signed-off-by: Stefano Brivio

checksum: Pass explicit L4 length to checksum functions

2026-05-19T23:21:38+00:00

The iov_tail passed to csum_iov_tail() may contain padding or trailing
data beyond the actual L4 payload.  Rather than relying on
iov_tail_size() to determine how many bytes to checksum, pass the
length explicitly so that only the relevant payload bytes are included
in the checksum computation.

Signed-off-by: Laurent Vivier 
Reviewed-by: David Gibson 
Reviewed-by: Jon Maloy 
Signed-off-by: Stefano Brivio

treewide: Make some additional variables static

2026-05-11T22:04:08+00:00

Mark a number of extra variables local to a single module as static.

Signed-off-by: David Gibson 
Reviewed-by: Laurent Vivier 
Signed-off-by: Stefano Brivio