* [PATCH] netlink: Drop point-to-point peer information when we copy addresses
@ 2024-04-11 22:18 Stefano Brivio
2024-04-23 1:02 ` David Gibson
0 siblings, 1 reply; 3+ messages in thread
From: Stefano Brivio @ 2024-04-11 22:18 UTC (permalink / raw)
To: passt-dev
If the template host interface is of type tun, and it's configured
with a point-to-point peer address (that's what happens for example
with openvpn and '--topology net30'), pasta will copy the peer
information onto the namespace interface.
But the namespace interface is not actually a point-to-point tunnel,
and we won't resolve the peer address via ARP either, so we have
to drop this information to get the expected behaviour (traffic
regularly sent over our tap interface).
Link: https://github.com/containers/podman/issues/22320
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
netlink.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/netlink.c b/netlink.c
index 89c0641..73aaa4b 100644
--- a/netlink.c
+++ b/netlink.c
@@ -792,8 +792,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
seq = nl_send(s_src, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
nl_foreach_oftype(nh, status, s_src, buf, seq, RTM_NEWADDR) {
+ struct rtattr *rta, *rta_local = NULL;
struct ifaddrmsg *ifa;
- struct rtattr *rta;
size_t na;
ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
@@ -804,12 +804,33 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
ifa->ifa_index = ifi_dst;
+ for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
+ rta = RTA_NEXT(rta, na)) {
+ if (rta->rta_type == IFA_LOCAL) {
+ rta_local = rta;
+ break;
+ }
+ }
+
for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
rta = RTA_NEXT(rta, na)) {
/* Strip label and expiry (cacheinfo) information */
if (rta->rta_type == IFA_LABEL ||
rta->rta_type == IFA_CACHEINFO)
rta->rta_type = IFA_UNSPEC;
+
+ /* Different values for IFA_ADDRESS and IFA_LOCAL mean
+ * that IFA_LOCAL is the locally configured address, and
+ * IFA_ADDRESS is the peer address for a point-to-point
+ * interface. But our namespace interface isn't really a
+ * point-to-point tunnel, and we can't resolve that peer
+ * address via ARP: simply drop it, and keep the local
+ * address.
+ */
+ if (rta->rta_type == IFA_ADDRESS && rta_local) {
+ memcpy(RTA_DATA(rta), RTA_DATA(rta_local),
+ RTA_PAYLOAD(rta));
+ }
}
rc = nl_do(s_dst, nh, RTM_NEWADDR,
--
@@ -792,8 +792,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
seq = nl_send(s_src, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
nl_foreach_oftype(nh, status, s_src, buf, seq, RTM_NEWADDR) {
+ struct rtattr *rta, *rta_local = NULL;
struct ifaddrmsg *ifa;
- struct rtattr *rta;
size_t na;
ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
@@ -804,12 +804,33 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
ifa->ifa_index = ifi_dst;
+ for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
+ rta = RTA_NEXT(rta, na)) {
+ if (rta->rta_type == IFA_LOCAL) {
+ rta_local = rta;
+ break;
+ }
+ }
+
for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
rta = RTA_NEXT(rta, na)) {
/* Strip label and expiry (cacheinfo) information */
if (rta->rta_type == IFA_LABEL ||
rta->rta_type == IFA_CACHEINFO)
rta->rta_type = IFA_UNSPEC;
+
+ /* Different values for IFA_ADDRESS and IFA_LOCAL mean
+ * that IFA_LOCAL is the locally configured address, and
+ * IFA_ADDRESS is the peer address for a point-to-point
+ * interface. But our namespace interface isn't really a
+ * point-to-point tunnel, and we can't resolve that peer
+ * address via ARP: simply drop it, and keep the local
+ * address.
+ */
+ if (rta->rta_type == IFA_ADDRESS && rta_local) {
+ memcpy(RTA_DATA(rta), RTA_DATA(rta_local),
+ RTA_PAYLOAD(rta));
+ }
}
rc = nl_do(s_dst, nh, RTM_NEWADDR,
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] netlink: Drop point-to-point peer information when we copy addresses
2024-04-11 22:18 [PATCH] netlink: Drop point-to-point peer information when we copy addresses Stefano Brivio
@ 2024-04-23 1:02 ` David Gibson
2024-04-23 8:09 ` Stefano Brivio
0 siblings, 1 reply; 3+ messages in thread
From: David Gibson @ 2024-04-23 1:02 UTC (permalink / raw)
To: Stefano Brivio; +Cc: passt-dev
[-- Attachment #1: Type: text/plain, Size: 2883 bytes --]
On Fri, Apr 12, 2024 at 12:18:00AM +0200, Stefano Brivio wrote:
> If the template host interface is of type tun, and it's configured
> with a point-to-point peer address (that's what happens for example
> with openvpn and '--topology net30'), pasta will copy the peer
> information onto the namespace interface.
>
> But the namespace interface is not actually a point-to-point tunnel,
> and we won't resolve the peer address via ARP either, so we have
> to drop this information to get the expected behaviour (traffic
> regularly sent over our tap interface).
>
> Link: https://github.com/containers/podman/issues/22320
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> ---
> netlink.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/netlink.c b/netlink.c
> index 89c0641..73aaa4b 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -792,8 +792,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
>
> seq = nl_send(s_src, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
> nl_foreach_oftype(nh, status, s_src, buf, seq, RTM_NEWADDR) {
> + struct rtattr *rta, *rta_local = NULL;
> struct ifaddrmsg *ifa;
> - struct rtattr *rta;
> size_t na;
>
> ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
> @@ -804,12 +804,33 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
>
> ifa->ifa_index = ifi_dst;
>
> + for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
> + rta = RTA_NEXT(rta, na)) {
> + if (rta->rta_type == IFA_LOCAL) {
> + rta_local = rta;
> + break;
> + }
> + }
> +
> for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
> rta = RTA_NEXT(rta, na)) {
> /* Strip label and expiry (cacheinfo) information */
> if (rta->rta_type == IFA_LABEL ||
> rta->rta_type == IFA_CACHEINFO)
> rta->rta_type = IFA_UNSPEC;
> +
> + /* Different values for IFA_ADDRESS and IFA_LOCAL mean
> + * that IFA_LOCAL is the locally configured address, and
> + * IFA_ADDRESS is the peer address for a point-to-point
> + * interface. But our namespace interface isn't really a
> + * point-to-point tunnel, and we can't resolve that peer
> + * address via ARP: simply drop it, and keep the local
> + * address.
Could we just unconditionally remove IFA_ADDRESS properties (by
setting them to IFA_UNSPEC)? That we we could avoid having two passes
through the attributes.
> + */
> + if (rta->rta_type == IFA_ADDRESS && rta_local) {
> + memcpy(RTA_DATA(rta), RTA_DATA(rta_local),
> + RTA_PAYLOAD(rta));
> + }
> }
>
> rc = nl_do(s_dst, nh, RTM_NEWADDR,
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] netlink: Drop point-to-point peer information when we copy addresses
2024-04-23 1:02 ` David Gibson
@ 2024-04-23 8:09 ` Stefano Brivio
0 siblings, 0 replies; 3+ messages in thread
From: Stefano Brivio @ 2024-04-23 8:09 UTC (permalink / raw)
To: David Gibson; +Cc: passt-dev
On Tue, 23 Apr 2024 11:02:43 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:
> On Fri, Apr 12, 2024 at 12:18:00AM +0200, Stefano Brivio wrote:
> > If the template host interface is of type tun, and it's configured
> > with a point-to-point peer address (that's what happens for example
> > with openvpn and '--topology net30'), pasta will copy the peer
> > information onto the namespace interface.
> >
> > But the namespace interface is not actually a point-to-point tunnel,
> > and we won't resolve the peer address via ARP either, so we have
> > to drop this information to get the expected behaviour (traffic
> > regularly sent over our tap interface).
> >
> > Link: https://github.com/containers/podman/issues/22320
> > Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> > ---
> > netlink.c | 23 ++++++++++++++++++++++-
> > 1 file changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/netlink.c b/netlink.c
> > index 89c0641..73aaa4b 100644
> > --- a/netlink.c
> > +++ b/netlink.c
> > @@ -792,8 +792,8 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
> >
> > seq = nl_send(s_src, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
> > nl_foreach_oftype(nh, status, s_src, buf, seq, RTM_NEWADDR) {
> > + struct rtattr *rta, *rta_local = NULL;
> > struct ifaddrmsg *ifa;
> > - struct rtattr *rta;
> > size_t na;
> >
> > ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
> > @@ -804,12 +804,33 @@ int nl_addr_dup(int s_src, unsigned int ifi_src,
> >
> > ifa->ifa_index = ifi_dst;
> >
> > + for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
> > + rta = RTA_NEXT(rta, na)) {
> > + if (rta->rta_type == IFA_LOCAL) {
> > + rta_local = rta;
> > + break;
> > + }
> > + }
> > +
> > for (rta = IFA_RTA(ifa), na = IFA_PAYLOAD(nh); RTA_OK(rta, na);
> > rta = RTA_NEXT(rta, na)) {
> > /* Strip label and expiry (cacheinfo) information */
> > if (rta->rta_type == IFA_LABEL ||
> > rta->rta_type == IFA_CACHEINFO)
> > rta->rta_type = IFA_UNSPEC;
> > +
> > + /* Different values for IFA_ADDRESS and IFA_LOCAL mean
> > + * that IFA_LOCAL is the locally configured address, and
> > + * IFA_ADDRESS is the peer address for a point-to-point
> > + * interface. But our namespace interface isn't really a
> > + * point-to-point tunnel, and we can't resolve that peer
> > + * address via ARP: simply drop it, and keep the local
> > + * address.
>
> Could we just unconditionally remove IFA_ADDRESS properties (by
> setting them to IFA_UNSPEC)? That we we could avoid having two passes
> through the attributes.
Ah, thanks, that sounds better, but I haven't tried it yet. By the way,
this patch doesn't fix the issue:
https://github.com/containers/podman/issues/22320#issuecomment-2051279807
so I think we need something on top of this, but I'm not sure yet what.
Other than tweaking routes, another idea might be to adjust the netmask
here.
--
Stefano
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-04-23 8:09 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-11 22:18 [PATCH] netlink: Drop point-to-point peer information when we copy addresses Stefano Brivio
2024-04-23 1:02 ` David Gibson
2024-04-23 8:09 ` Stefano Brivio
Code repositories for project(s) associated with this public inbox
https://passt.top/passt
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for IMAP folder(s).