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ipv6ll: don't regenerate the address when it's removed externally

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Currently if the IPv6 link-local address is removed after it passed
DAD, NetworkManager tries to generate a new link-local address. If
this fails, which is always the case for EUI64, ipv6ll is considered
as failed and the connection can go down (depending on may-fail).

This is particularly bad for virtual interfaces because if somebody
removes the link-local address, the activation can fail and destroy
the interface, breaking all services that require it. Also, it's a
change in behavior introduced in 1.36.0.

It seems that a better approach here is to re-add the address that was
removed externally.

[bgalvani@redhat.com: since the branch is missing commit 7ca95cee15
('platform: always reconfigure IP routes even if removed externally'),
we need to set flag NM_L3CFG_CONFIG_FLAGS_FORCE_ONCE when committing
the address, otherwise it's not re-added]

Fixes: aa070fb821 ('core: add NML3IPv6LL helper')
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1622
(cherry picked from commit 53ba9f4701)
(cherry picked from commit 2976e4c3b7)
This commit is contained in:
Beniamino Galvani 2023-05-11 13:32:13 +02:00
parent f6f1a44559
commit 4a13b5f522
1 changed files with 22 additions and 12 deletions
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34
src/core/nm-l3-ipv6ll.c
View file

@ -391,7 +391,7 @@ _pladdr_find_ll(NML3IPv6LL *self, gboolean *out_cur_addr_failed)
/*****************************************************************************/
static void
_lladdr_handle_changed(NML3IPv6LL *self)
_lladdr_handle_changed(NML3IPv6LL *self, gboolean force_commit)
{
const NML3ConfigData *l3cd;
gboolean changed = FALSE;
@ -420,7 +420,9 @@ _lladdr_handle_changed(NML3IPv6LL *self)
NM_DNS_PRIORITY_DEFAULT_NORMAL,
NM_L3_ACD_DEFEND_TYPE_ALWAYS,
0,
NM_L3CFG_CONFIG_FLAGS_NONE,
/* Even if the address was removed from platform, it must
* be re-added, hence FORCE_ONCE. */
NM_L3CFG_CONFIG_FLAGS_FORCE_ONCE,
NM_L3_CONFIG_MERGE_FLAGS_NONE))
changed = TRUE;
} else {
@ -434,7 +436,7 @@ _lladdr_handle_changed(NML3IPv6LL *self)
self->l3cfg_commit_handle,
"ipv6ll");
if (changed)
if (changed || force_commit)
nm_l3cfg_commit_on_idle_schedule(self->l3cfg, NM_L3_CFG_COMMIT_TYPE_AUTO);
if (!self->emit_changed_idle_source) {
@ -515,6 +517,7 @@ _check(NML3IPv6LL *self)
const NMPlatformIP6Address *pladdr;
char sbuf[INET6_ADDRSTRLEN];
gboolean cur_addr_failed;
gboolean restarted = FALSE;
struct in6_addr lladdr;
pladdr = _pladdr_find_ll(self, &cur_addr_failed);
@ -526,14 +529,14 @@ _check(NML3IPv6LL *self)
if (_set_cur_lladdr_obj(self, NM_L3_IPV6LL_STATE_DAD_IN_PROGRESS, pladdr)) {
_LOGT("changed: waiting for address %s to complete DAD",
_nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
_lladdr_handle_changed(self);
_lladdr_handle_changed(self, FALSE);
}
return;
}
if (_set_cur_lladdr_obj(self, NM_L3_IPV6LL_STATE_READY, pladdr)) {
_LOGT("changed: address %s is ready", _nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
_lladdr_handle_changed(self);
_lladdr_handle_changed(self, FALSE);
}
return;
}
@ -543,11 +546,17 @@ _check(NML3IPv6LL *self)
* Prematurely abort DAD to generate a new address below. */
nm_assert(
NM_IN_SET(self->state, NM_L3_IPV6LL_STATE_DAD_IN_PROGRESS, NM_L3_IPV6LL_STATE_READY));
if (self->state == NM_L3_IPV6LL_STATE_DAD_IN_PROGRESS)
_LOGT("changed: address %s did not complete DAD",
_nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
else {
if (cur_addr_failed) {
/* On DAD failure, we always try to regenerate a new address. */
_LOGT("changed: address %s failed", _nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
} else {
_LOGT("changed: address %s is gone", _nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
/* When the address is removed, we always try to re-add it. */
nm_clear_g_source_inst(&self->wait_for_addr_source);
lladdr = self->cur_lladdr;
restarted = TRUE;
goto commit;
}
/* reset the state here, so that we are sure that the following
@ -569,19 +578,20 @@ _check(NML3IPv6LL *self)
if (_set_cur_lladdr_bin(self, NM_L3_IPV6LL_STATE_DAD_FAILED, NULL)) {
_LOGW("changed: no IPv6 link local address to retry after Duplicate Address Detection "
"failures (back off)");
_lladdr_handle_changed(self);
_lladdr_handle_changed(self, FALSE);
}
return;
}
commit:
/* we give NML3Cfg 2 seconds to configure the address on the interface. We
* thus very soon expect to see this address configured (and kernel started DAD).
* If that does not happen within timeout, we assume that this address failed DAD. */
self->wait_for_addr_source = nm_g_timeout_add_source(2000, _wait_for_addr_timeout_cb, self);
if (_set_cur_lladdr_bin(self, NM_L3_IPV6LL_STATE_DAD_IN_PROGRESS, &lladdr)) {
if (_set_cur_lladdr_bin(self, NM_L3_IPV6LL_STATE_DAD_IN_PROGRESS, &lladdr) || restarted) {
_LOGT("changed: starting DAD for address %s",
_nm_utils_inet6_ntop(&self->cur_lladdr, sbuf));
_lladdr_handle_changed(self);
_lladdr_handle_changed(self, restarted);
}
return;
}