In fecb1b65b1 ("log: Don't prefix message with timestamp on --debug
if it's a continuation"), I fixed this for --debug on standard error,
but not for log files: if messages are continuations, they shouldn't
be prefixed by timestamp and severity.
Otherwise, we'll print stuff like this:
0.0028: ERROR: Receive error on guest connection, reset0.0028: ERROR: : Bad file descriptor
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
On some systems source fortification is enabled whenever code
optimization is enabled (e.g. with -O2). Since code fortification
is explicitly enabled too (with possibly different value than the
system wants, there are three levels [1]), distros are required
to patch our Makefile, e.g. [2].
Detect whether fortification is not already enabled and enable it
explicitly only if really needed.
1: https://www.gnu.org/software/libc/manual/html_node/Source-Fortification.html
2: edfeb8763a
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
When we forward "all" ports (-t all or -u all), or use an exclude-only
range, we don't actually forward *all* ports - that wouln't leave local
ports to use for outgoing connections. Rather we forward all non-ephemeral
ports - those that won't be used for outgoing connections or datagrams.
Currently we assume the range of ephemeral ports is that recommended by
RFC 6335, 49152-65535. However, that's not the range used by default on
Linux, 32768-60999 but configurable with the net.ipv4.ip_local_port_range
sysctl.
We can't really know what range the guest will consider ephemeral, but if
it differs too much from the host it's likely to cause problems we can't
avoid anyway. So, using the host's ephemeral range is a better guess than
using the RFC 6335 range.
Therefore, add logic to probe the host's ephemeral range, falling back to
the RFC 6335 range if that fails. This has the bonus advantage of
reducing the number of ports bound by -t all -u all on most Linux machines
thereby reducing kernel memory usage. Specifically this reduces kernel
memory usage with -t all -u all from ~380MiB to ~289MiB.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
When using -t all, -u all or exclude-only ranges, we'll attempt to forward
all non-ephemeral port numbers, including port 0. However, this won't work
as intended: bind() treats a zero port not as literal port 0, but as
"pick a port for me". Because of the special meaning of port 0, we mostly
outright exclude it in our handling.
Do the same for setting up forwards, not attempting to forward for port 0.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
"Ephemeral" ports are those which the kernel may allocate as local
port numbers for outgoing connections or datagrams. Because of that,
they're generally not good choices for listening servers to bind to.
Thefore when using -t all, -u all or exclude-only ranges, we map only
non-ephemeral ports. Our logic for this is a bit rigid though: we
assume the ephemeral ports are always a fixed range at the top of the
port number space. We also assume PORT_EPHEMERAL_MIN is a multiple of
8, or we won't set the forward bitmap correctly.
Make the logic in conf.c more flexible, using a helper moved into
fwd.[ch], although we don't change which ports we consider ephemeral
(yet).
The new handling is undoubtedly more computationally expensive, but
since it's a once-off operation at start off, I don't think it really
matters.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Avoid excess lines on wide terminals, but make sure we don't fail if
we can't fetch the number of columns for any reason, as it's not a
fundamental feature and we don't want to break anything with it.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Platforms like Linux allow IPv6 sockets to listen for IPv4 connections as
well as native IPv6 connections. By doing this we halve the number of
listening sockets we need (assuming passt/pasta is listening on the same
ports for IPv4 and IPv6). When forwarding many ports (e.g. -u all) this
can significantly reduce the amount of kernel memory that passt consumes.
We've used such dual stack sockets for TCP since 8e914238b "tcp: Use dual
stack sockets for port forwarding when possible". Add similar support for
UDP "listening" sockets. Since UDP sockets don't use as much kernel memory
as TCP sockets this isn't as big a saving, but it's still significant.
When forwarding all TCP and UDP ports for both IPv4 & IPv6 (-t all -u all),
this reduces kernel memory usage from ~522 MiB to ~380MiB (kernel version
6.10.6 on Fedora 40, x86_64).
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
The 's' variable is always redundant with either 'r4' or 'r6', so remove
it.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We've already gotten rid of most of the IPv4/IPv6 specific data structures
in udp.c by merging them with each other. One significant one remains:
udp[46]_mh_recv. This was a bit awkward to remove because of a subtle
interaction. We initialise the msg_namelen fields to represent the total
size we have for a socket address, but when we receive into the arrays
those are modified to the actual length of the sockaddr we received.
That meant that naively merging the arrays meant that if we received IPv4
datagrams, then IPv6 datagrams, the addresses for the latter would be
truncated. In this patch address that by resetting the received
msg_namelen as soon as we've found a flow for the datagram. Finding the
flow is the only thing that might use the actual sockaddr length, although
we in fact don't need it for the time being.
This also removes the last use of the 'v6' field from udp_listen_epoll_ref,
so remove that as well.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Some distributions already have OpenSSH 9.8, which introduces split
sshd/sshd-session binaries, and there we need to copy the binary from
the host, which can be /usr/libexec/openssh/sshd-session (Fedora
Rawhide), /usr/lib/ssh/sshd-session (Arch Linux),
/usr/lib/openssh/sshd-session (Debian), and possibly other paths.
Add at least those three, and, if we don't find sshd-session, assume
we don't need it: it could very well be an older version of OpenSSH,
as reported by David for Fedora 40, or perhaps another daemon (would
Dropbear even work? I'm not sure).
Reported-by: David Gibson <david@gibson.dropbear.id.au>
Fixes: d6817b3930 ("test/passt.mbuto: Install sshd-session OpenSSH's split process")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Seen with krun: we get a file descriptor via --fd, but we close it and
happily use the same number for TCP files.
The issue is that if we also get other options before --fd, with
arguments, getopt_long() stops parsing them because it sees them as
non-option values.
Use the - modifier at the beginning of optstring (before :, which is
needed to avoid printing errors) instead of +, which means we'll
continue parsing after finding unrelated option values, but
getopt_long() won't reorder them anyway: they'll be passed with option
value '1', which we can ignore.
By the way, we also need to add : after F in the optstring, so that
we're able to parse the option when given as short name as well.
Now that we change the parsing mode between close_open_files() and
conf(), we need to reset optind to 0, not to 1, whenever we call
getopt_long() again in conf(), so that the internal initialisation
of getopt_long() evaluating GNU extensions is re-triggered.
Link: https://github.com/slp/krun/issues/17#issuecomment-2294943828
Fixes: baccfb95ce ("conf: Stop parsing options at first non-option argument")
Fixes: 09603cab28 ("passt, util: Close any open file that the parent might have leaked")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Mostly packages we now need to run Podman-based tests.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
These system calls are needed after the conversion of time_t to 64-bit
types on 32-bit architectures.
Tested by running some transfer tests with passt and pasta on Debian
Bookworm (glibc 2.36) and Trixie (glibc 2.39), running on armv6l.
Suggested-by: Faidon Liambotis <paravoid@debian.org>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1078981
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
musl, as of 1.2.5, and glibc < 2.34 don't ship a (trivial)
close_range() implementation. This will probably be added to musl
soon, by the way:
https://www.openwall.com/lists/musl/2024/08/01/9
Add a weakly-aliased implementation, if it's supported by the kernel.
If it's not supported (< 5.9), use a no-op fallback. Looping over 2^31
file descriptors calling close() on them is probably not a good idea.
Reported-by: lemmi <lemmi@nerd2nerd.org>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
For some reason, this is reported only with musl, and older glibc
versions (2.31, at least).
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Some architectures, including i686, actually have a recv() system
call, not just a recvfrom(), and we need to cover the recv() with
MSG_TRUNC into a NULL buffer for them as well.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
OpenSSH now ships a per-session binary, sshd-session, with sshd
acting as mere listener. It's typically not found in $PATH, so specify
the whole path at which it's commonly installed in $PROGS.
Link: https://www.openssh.com/releasenotes.html#9.8p1
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
It's qemu-system-i386, but uname -m reports i686. I didn't test i486
and i586.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
I haven't tested i386 for a long time (after playing with some
openSUSE i586 image a couple of years ago). It turns out that a number
of system calls we actually need were denied by the seccomp filter,
and not even basic functionality works.
Add some system calls that glibc started using with the 64-bit time
("t64") transition, see also:
https://wiki.debian.org/ReleaseGoals/64bit-time
that is: clock_gettime64, timerfd_gettime64, fcntl64, and
recvmmsg_time64.
Add further system calls that are needed regardless of time_t width,
that is, mmap2 (valgrind profile only), _llseek and sigreturn (common
outside x86_64), and socketcall (same as s390x).
I validated this against an almost full run of the test suite, with
just a few selected tests skipped. Fixes needed to run most tests on
i386/i686, and other assorted fixes for tests, are included in
upcoming patches.
Reported-by: Uroš Knupleš <uros@knuples.net>
Analysed-by: Faidon Liambotis <paravoid@debian.org>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1078981
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
The guest is usually assigned one of the host's IP addresses. That means
it can't access the host itself via its usual address. The
--map-host-loopback option (enabled by default with the gateway address)
allows the guest to contact the host. However, connections forwarded this
way appear on the host to have originated from the loopback interface,
which isn't always desirable.
Add a new --map-guest-addr option, which acts similarly but forwarded
connections will go to the host's external address, instead of loopback.
If '-a' is used, so the guest's address is not the same as the host's, this
will instead forward to whatever host-visible site is shadowed by the
guest's assigned address.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
fwd_nat_from_host() needs to adjust the source address for new flows coming
from an address which is not accessible to the guest. Currently we always
use our_tap_addr or our_tap_ll. However in cases where the address is
accessible to the guest via translation (i.e. via --map-host-loopback) then
it makes more sense to use that translation, rather than the fallback
mapping of our_tap_*.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Because the host and guest share the same IP address with passt/pasta, it's
not possible for the guest to directly address the host. Therefore we
allow packets from the guest going to a special "NAT to host" address to be
redirected to the host, appearing there as though they have both source and
destination address of loopback.
Currently that special address is always the address of the default
gateway (or none). That can be a problem if we want that gateway to be
addressable by the guest. Therefore, allow the special "NAT to host"
address to be overridden on the command line with a new --map-host-loopback
option.
In order to exercise and test it, update the passt_in_ns and perf
tests to use this option and give different mapping addresses for the
two layers of the environment.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In the TCP throughput tests, we adjust the guest's MTU in order to test
various packet sizes. Some of those are below 1280 which causes IPv6 to
be deconfigured on the guest interface. When we increase it above 1280
again, IPv6 is re-enabled and we get an address in the right prefix with
NDP, but we don't get exactly the expected address back - that's only
communicated with --config-net or DHCPv6.
With changes to how we handle NAT this can cause some of the IPv6 tests to
fail, because they don't use the address that passt/pasta expects, and the
guest doesn't initiate any traffic which allows us to learn what the new
address is.
Work around this by re-invoking dhclient -6 between adjusting the MTU and
running IPv6 test cases.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
The @gw fields in the ip4_ctx and ip6_ctx give the (host's) default
gateway. We use this for two quite distinct things: advertising the
gateway that the guest should use (via DHCP, NDP and/or --config-net)
and for a limited form of NAT. So that the guest can access services
on the host, we map the gateway address within the guest to the
loopback address on the host.
Using the gateway address for this isn't necessarily the best choice
for this purpose, certainly not for all circumstances. So, start off
by splitting the notion of these into two different values: @guest_gw
which is the gateway address the guest should use and @nat_host_loopback,
which is the guest visible address to remap to the host's loopback.
Usually nat_host_loopback will have the same value as guest_gw. However
when --no-map-gw is specified we leave them unspecified instead. This
means when we use nat_host_loopback, we don't need to separately check
c->no_map_gw to see if it's relevant.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
When sending frames to the guest over the tap link, we need a source MAC
address. Currently we take that from the MAC address of the main interface
on the host, but that doesn't actually make much sense:
* We can't preserve the real MAC address of packets from anywhere
external so there's no transparency case here
* In fact, it's confusingly different from how we handle IP addresses:
whereas we give the guest the same IP as the host, we're making the
host's MAC the one MAC that the guest *can't* use for itself.
* We already need a fallback case if the host doesn't have an Ethernet
like MAC (e.g. if it's connected via a point to point interface, such
as a wireguard VPN).
Change to just just use an arbitrary fixed MAC address - I've picked
9a:55:9a:55:9a:55. It's simpler and has the small advantage of making
the fact that passt/pasta is in use typically obvious from guest side
packet dumps. This can still, of course, be overridden with the -M option.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
ip4.gw conflates 3 conceptually different things, which (for now) have the
same value:
1. The router/gateway address as seen by the guest
2. An address to NAT to the host with --no-map-gw isn't specified
3. An address to use as source when nothing else makes sense
Case 3 occurs in two situations:
a) for our DHCP responses - since they come from passt internally there's
no naturally meaningful address for them to come from
b) for forwarded connections coming from an address that isn't guest
accessible (localhost or the guest's own address).
(b) occurs even with --no-map-gw, and the expected behaviour of forwarding
local connections requires it.
For IPv6 role (3) is now taken by ip6.our_tap_ll (which usually has the
same value as ip6.gw). For future flexibility we may want to make this
"address of last resort" different from the gateway address, so split them
logically for IPv4 as well.
Specifically, add a new ip4.our_tap_addr field for the address with this
role, and initialise it to ip4.gw for now. Unlike IPv6 where we can always
get a link-local address, we might not be able to get a (non 0.0.0.0)
address here (e.g. if the host is disconnected or only has a point to point
link with no gateway address). In that case we have to disable forwarding
of inbound connections with guest-inaccessible source addresses.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We usually avoid NAT, but in a few cases we need to apply address
translations. For inbound connections that happens for addresses which
make sense to the host but are either inaccessible, or mean a different
location from the guest's point of view.
Add some helper functions to determine such addresses, and use them in
fwd_nat_from_host(). In doing so clarify some of the reasons for the
logic. We'll also have further use for these helpers in future.
While we're there fix one unneccessary inconsistency between IPv4 and IPv6.
We always translated the guest's observed address, but for IPv4 we didn't
translate the guest's assigned address, whereas for IPv6 we did. Change
this to translate both in all cases for consistency.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In every place we use our_tap_ll, we only use it as a fallback if the
IPv6 gateway address is not link-local. We can avoid that conditional at
use time by doing it at initialisation of our_tap_ll instead.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Some are guest visible addresses and may not be valid on the host, others
are host visible addresses and may not be valid on the guest. Rearrange
and comment the ip[46]_ctx definitions to make it clearer which is which.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
c->ip6.addr_ll is not like c->ip6.addr. The latter is an address for the
guest, but the former is an address for our use on the tap link. Rename it
accordingly, to 'our_tap_ll'.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
When binding an IPv6 socket in sock_l4() we need to supply a scope id
if the address is link-local. We check for this by comparing the
given address to c->ip6.addr_ll. This is correct only by accident:
while c->ip6.addr_ll is typically set to the host interface's link
local address, the actual purpose of it is to provide a link local
address for passt's private use on the tap interface.
Instead set the scope id for any link-local address we're binding to.
We're going to need something and this is what makes sense for sockets
on the host. It doesn't make sense for PIF_SPLICE sockets, but those
should always have loopback, not link-local addresses.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Despite the names, addr_ll_seen does not relate to addr_ll the same
way addr_seen relates to addr. addr_ll_seen is an observed address
from the guest, whereas addr_ll is *our* link-local address for use on
the tap link when we can't use an external endpoint address. It's
used both for passt provided services (DHCPv6, NDP) and in some cases
for connections from addresses the guest can't access.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Although it's not 100% explicit in the man page, addresses given to
the --dns option are intended to be addresses as seen by the guest.
This differs from addresses taken from the host's /etc/resolv.conf,
which must be translated to guest accessible versions in some cases.
Our implementation is currently inconsistent on this: when using
--dns-forward, you must usually also give --dns with the matching address,
which is meaningful only in the guest's address view. However if you give
--dns with a loopback addres, it will be translated like a host view
address.
Move the remapping logic for DNS addresses out of add_dns4() and add_dns6()
into add_dns_resolv() so that it is only applied for host nameserver
addresses, not for nameservers given explicitly with --dns.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
add_dns6() (but not add_dns4()) has a bug setting dns_match: it sets it to
the given address, rather than the gateway address. This is doubly wrong:
- We've just established the given address is a host loopback address
the guest can't access
- We've just set ip6.dns[] to tell the guest to use the gateway address,
so it won't use the dns_match address we're setting
Correct this to use the gateway address, like IPv4.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
get_dns() is already quite deeply nested, and future changes I have in
mind will add more complexity. Prepare for this by splitting out the
adding of a single nameserver to the configuration into its own function.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Every time we call add_dns[46] we need to first check if there's space in
the c->ip[46].dns array for the new entry. We might as well make that
check in add_dns[46]() itself.
In fact it looks like the calls in get_dns() had an off by one error, not
allowing the last entry of the array to be filled. So, that bug is also
fixed by the change.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
get_dns() counts the number of guest DNS servers it adds, and gives an
error if it couldn't add any. However, this count ignores the fact that
add_dns[46]() may in some cases *not* add an entry. Use the array indices
we're already tracking to get an accurate count.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Currently add_dns[46]() take a somewhat awkward double pointer to the
entry in the c->ip[46].dns array to update. It turns out to be easier to
work with indices into that array instead.
This diff does add some lines, but it's comments, and will allow some
future code reductions.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
We rely on C11 already, so we can use clearer and more type-checkable
struct assignment instead of mempcy() for copying IP addresses around.
This exposes some "pointer could be const" warnings from cppcheck, so
address those too.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
c->mac isn't a great name, because it doesn't say whose mac address it is
and it's not necessarily obvious in all the contexts we use it. Since this
is specifically the address that we (passt/pasta) use on the tap interface,
rename it to "our_tap_mac". Rename the "mac_guest" field to "guest_mac"
to be grammatically consistent.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
There are a couple of places where we somewhat messily open code formatting
an Ethernet like MAC address for display. Add an eth_ntop() helper for
this.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
The term "forwarding address" to indicate the local-to-passt address was
well-intentioned, but ends up being kinda confusing. As discussed on a
recent call, let's try "our" instead.
(While we're there correct an error in flow_initiate_af()s comments where
we referred to parameters by the wrong name).
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
As soon as we the kernel notifier for IPv6 address configuration
(addrconf_notify()) sees that we bring the target interface up
(NETDEV_UP), it will schedule duplicate address detection, so, by
itself, setting the nodad flag later is useless, because that won't
stop a detection that's already in progress.
However, if we disable neighbour solicitations with IFF_NOARP (which
is a misnomer for IPv6 interfaces, but there's no possibility of
mixing things up), the notifier will not trigger DAD, because it can't
be done, of course, without neighbour solicitations.
Set IFF_NOARP as we bring up the device, and drop it after we had a
chance to set the nodad attribute on the link.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
As soon as we bring up the interface, the Linux kernel will set up a
link-local address for it, so we can fetch it and start using right
away, if we need a link-local address to communicate to the container
before we see any traffic coming from it.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
It makes no sense for a container or a guest to try and perform
duplicate address detection for their link-local address, as we'll
anyway not relay neighbour solicitations with an unspecified source
address.
While they perform duplicate address detection, the link-local address
is not usable, which prevents us from bringing up especially
containers and communicate with them right away via IPv6.
This is not enough to prevent DAD and reach the container right away:
we'll need a couple more patches.
As we send NLM_F_REPLACE requests right away, while we still have to
read out other addresses on the same socket, we can't use nl_do():
keep track of the last sequence we sent (last address we changed), and
deal with the answers to those NLM_F_REPLACE requests in a separate
loop, later.
Link: https://github.com/containers/podman/pull/23561#discussion_r1711639663
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
