passt/netlink.c, branch 2026_05_07.1afd4ed

treewide: Spell ASSERT() as assert()

2026-03-20T20:05:29+00:00

The standard library assert(3), at least with glibc, hits our seccomp
filter and dies with SIGSYS before it's able to print a message, making it
near useless.  Therefore, since 7a8ed9459dfe ("Make assertions actually
useful") we've instead used our own implementation, named ASSERT().

This makes our code look slightly odd though - ASSERT() has the same
overall effect as assert(), it's just a different implementation.  More
importantly this makes it awkward to share code between passt/pasta proper
and things that compile in a more typical environment.  We're going to want
that for our upcoming dynamic configuration tool.

Address this by overriding the standard library's assert() implementation
with our own, instead of giving ours its own name.

The standard assert() is supposed to be omitted if NDEBUG is defined,
which ours doesn't do.  Implement that as well, so ours doesn't
unexpectedly differ.  For the -DNDEBUG case we do this by *not* overriding
assert(), since it will be a no-op anyway.  This requires a few places to
add a #include  to let us compile (albeit with warnings) when
-DNDEBUG.

Signed-off-by: David Gibson 
[sbrivio: Fix some conflicts and missing conversions as a result of
 applying "vu_common: Move iovec management into vu_collect()" first]
Signed-off-by: Stefano Brivio

netlink: Allow NULL to be passed as addr parameter to nl_addr_get (again)

2026-03-11T21:11:30+00:00

A recent fix to nl_addr_get() unfortunately introduced a different problem.
251e676bd0bf removed a test if @addr was non-NULL.  conf_ip6() relied on
being able to pass NULL in order to update the link-local address without
updating the main address (because it was already set by the user).

This means that 'pasta -a 2001:db8::1' will SEGV.  Reverse the incorrect
part of the change to fix this.

Fixes: 251e676bd0bf ("netlink: Return prefix length for IPv6 addresses in nl_addr_get()")
Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

netlink: Return prefix length for IPv6 addresses in nl_addr_get()

2026-03-10T14:28:11+00:00

nl_addr_get() was not setting the prefix_len output parameter for
IPv6 addresses, only for IPv4. This meant callers always got 0 for
IPv6, forcing them to use a hardcoded default (64).

Fix by assigning *prefix_len even in the IPv6 case.

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

epoll_ctl: Extract epoll operations

2025-10-30T14:32:12+00:00

Centralize epoll_add() and epoll_del() helper functions into new
epoll_ctl.c/h files.

This also moves the union epoll_ref definition from passt.h to
epoll_ctl.h where it's more logically placed.

The new epoll_add() helper simplifies adding file descriptors to epoll
by taking an epoll_ref and events, handling error reporting
consistently across all call sites.

Signed-off-by: Laurent Vivier 
[sbrivio: Include epoll_ctl.h from netlink.c as it's now needed there]
Reviewed-by: David Gibson 
Signed-off-by: Stefano Brivio

fwd: Add cache table for ARP/NDP contents

2025-10-30T11:01:01+00:00

We add a cache table to keep track of the contents of the kernel ARP
and NDP tables. The table is fed from the just introduced netlink based
neigbour subscription function.

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

netlink: add subscription on changes in NDP/ARP table

2025-10-30T11:00:49+00:00

The solution to bug https://bugs.passt.top/show_bug.cgi?id=120
requires the ability to translate from an IP address to its
corresponding MAC address in cases where those are present in
the ARP or NDP tables.

To keep track of the contents of these tables we add a netlink
based neighbour subscription feature.

Signed-off-by: Jon Maloy 
Reviewed-by: David Gibson 
[sbrivio: Fix format modifier for ndm->ndm_state, reported by dwg]
Signed-off-by: Stefano Brivio

netlink: Don't require address to be global, just not link local

2025-09-30T10:03:39+00:00

nl_addr_get() will only pick up global IPv6 addresses (RT_SCOPE_UNIVERSE).
This is because link-local addresses aren't suitable.  However site-local
addresses (in the rare occassions they're used) would be fine for our
purposes.  In fact, anything wider than link scope is fine, so update the
check to reflect that.

Change the logic in the test scripts to match as well.

Reported-by: Xun Gu 
Link: https://bugs.passt.top/show_bug.cgi?id=122
Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

netlink: Drop nexthop state flags from routes we duplicate

2025-09-19T17:30:00+00:00

The kernel doesn't like those (EINVAL) on RTM_NEWROUTE, as they are
flags representing states, not configuration.

Link: https://github.com/containers/podman/discussions/27104
Signed-off-by: Stefano Brivio 
Reviewed-by: David Gibson 
Reviewed-by: Paul Holzinger

style: Add parentheses to function names in comments

2025-07-18T17:19:37+00:00

The commit updates the style of function comments by adding parentheses
to function names in the descriptions where they are missing.

Done with:

---------8<------ fix_function_name.awk ---------8<------
/^\/\*\*/ {
    check_next = 1;
    print $0
    next
}
check_next == 1 && / \* struct/ {
    check_next = 0
    print $0
    next
}
check_next == 1 && / \* enum/ {
    check_next = 0
    print $0
    next
}
check_next == 1 && /^ \* [^ (]* -/ {
   modified_line = gensub(/^ \* ([^ ]*) -(.*)$/, " * \\1() -\\2", "g", $0)
   print modified_line
   check_next = 0;
   next
}
{
    print $0
    check_next = 0
}
---------8<------ fix_function_name.awk ---------8<------

Then

for file in *.[ch]; do
    cp ${file} ${file}.tmp && \
    awk -f fix_function_name.awk ${file}.tmp > ${file}
done

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio

Correct various function comment headers

2025-06-04T10:32:04+00:00

This commit refines function comment headers for improved accuracy
and consistency. Key changes include:

- Corrected parameter/return descriptions (e.g., `logtime`, `__daemon`).
- Added missing and removed incorrect parameter documentation (e.g.,
  `tcp_vu_sock_recv`, `ndp`).
- Standardized comments to the `/** ... */` style for functions
  like `udp_flow_close` and `ns_enter`.
- Ensured function names in comments consistently use `()`.
- Addressed minor typos and updated comments for renamed functions.

Signed-off-by: Laurent Vivier 
Signed-off-by: Stefano Brivio