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platform: better handle ip route replace for ignored routes

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We don't cache certain routes, for example based on the protocol. This is
a performance optimization to ignore routes that we usually don't care
about.

Still, if the user does `ip route replace` with such a route, then we
need to pass it to nmp_cache_update_netlink_route(), so that we can
properly remove the replaced route.

Knowing which route was replaces might be impossible, as our cache does
not contain all routes. Likely all that nmp_cache_update_netlink_route()
can to is to set "resync_required" for NLM_F_REPLACE. But for that it
should see the object first.

This also means, if we ever write a BPF filter to filter out messages
that contain NLM_F_REPLACE, because that would lead to cache inconsistencies.
This commit is contained in:
Thomas Haller 2022-11-18 18:00:33 +01:00
parent c64053e6e6
commit 854f2cc1fc
No known key found for this signature in database
GPG key ID: 29C2366E4DFC5728
4 changed files with 19 additions and 20 deletions
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1
src/core/platform/nm-fake-platform.c
View file

@ -1232,6 +1232,7 @@ ip_route_add(NMPlatform *platform, NMPNlmFlags flags, NMPObject *obj_stack)
obj,
FALSE,
nlmsgflags,
TRUE,
&obj_old,
&obj_new,
&obj_replace,

34
src/libnm-platform/nm-linux-platform.c
View file

@ -5308,7 +5308,7 @@ ip_route_get_lock_flag(const NMPlatformIPRoute *route)
}
static gboolean
ip_route_ignored_protocol(const NMPlatformIPRoute *route)
ip_route_is_alive(const NMPlatformIPRoute *route)
{
guint8 prot;
@ -5320,12 +5320,18 @@ ip_route_ignored_protocol(const NMPlatformIPRoute *route)
nm_assert(nmp_utils_ip_config_source_from_rtprot(prot) == route->rt_source);
/* We ignore all routes outside a certain subest of rtm_protocol. NetworkManager
* itself wouldn't configure those, so they are always configured by somebody
* external. We thus ignore them to avoid the overhead that processing them brings.
* For example, the BGP daemon "bird" might configure a huge number of RTPROT_BIRD routes. */
if (prot > RTPROT_STATIC && !NM_IN_SET(prot, RTPROT_DHCP, RTPROT_RA)) {
/* We ignore certain rtm_protocol, because NetworkManager would only ever
* configure certain protocols. Other routes are not configured by NetworkManager
* and we don't track them in the platform cache.
*
* This is to help with the performance overhead of a huge number of
* routes, for example with the bird BGP software, that adds routes
* with RTPROT_BIRD protocol. */
return FALSE;
}
return prot > RTPROT_STATIC && !NM_IN_SET(prot, RTPROT_DHCP, RTPROT_RA);
return TRUE;
}
/* Copied and modified from libnl3's build_route_msg() and rtnl_route_build_msg(). */
@ -7829,6 +7835,7 @@ _rtnl_handle_msg(NMPlatform *platform, const struct nl_msg_lite *msg)
gboolean resync_required = FALSE;
gboolean only_dirty = FALSE;
gboolean is_ipv6;
gboolean route_is_alive;
/* IPv4 routes that are a response to RTM_GETROUTE must have
* the cloned flag while IPv6 routes don't have to. */
@ -7858,24 +7865,13 @@ _rtnl_handle_msg(NMPlatform *platform, const struct nl_msg_lite *msg)
}
}
if (ip_route_ignored_protocol(NMP_OBJECT_CAST_IP_ROUTE(obj))) {
/* We ignore certain rtm_protocol, because NetworkManager would only ever
* configure certain protocols. Other routes were not added by NetworkManager
* and we don't need to track them in the platform cache.
*
* This is to help with the performance overhead of a huge number of
* routes, for example with the bird BGP software, that adds routes
* with RTPROT_BIRD protocol.
*
* Even if this is a IPv6 multipath route, we abort (parse_nlmsg_iter). There
* is nothing for us to do. */
return;
}
route_is_alive = ip_route_is_alive(NMP_OBJECT_CAST_IP_ROUTE(obj));
cache_op = nmp_cache_update_netlink_route(cache,
obj,
is_dump,
msghdr->nlmsg_flags,
route_is_alive,
&obj_old,
&obj_new,
&obj_replace,

3
src/libnm-platform/nmp-object.c
View file

@ -2959,6 +2959,7 @@ nmp_cache_update_netlink_route(NMPCache *cache,
NMPObject *obj_hand_over,
gboolean is_dump,
guint16 nlmsgflags,
gboolean route_is_alive,
const NMPObject **out_obj_old,
const NMPObject **out_obj_new,
const NMPObject **out_obj_replace,
@ -2990,7 +2991,7 @@ nmp_cache_update_netlink_route(NMPCache *cache,
NM_SET_OUT(out_obj_old, nmp_object_ref(nm_dedup_multi_entry_get_obj(entry_old)));
is_alive = nmp_object_is_alive(obj_hand_over);
is_alive = route_is_alive && nmp_object_is_alive(obj_hand_over);
if (!entry_old) {
if (is_alive) {

1
src/libnm-platform/nmp-object.h
View file

@ -973,6 +973,7 @@ NMPCacheOpsType nmp_cache_update_netlink_route(NMPCache *cache,
NMPObject *obj_hand_over,
gboolean is_dump,
guint16 nlmsgflags,
gboolean route_is_alive,
const NMPObject **out_obj_old,
const NMPObject **out_obj_new,
const NMPObject **out_obj_replace,