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Merge branch 'ipv6-report-why-a-route-was-deleted-in-rtm_delroute'

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Yuyang Huang says:

====================
ipv6: report why a route was deleted in RTM_DELROUTE

When the kernel deletes an IPv6 route on its own, the RTM_DELROUTE
notification does not say why. User space cannot tell a route that
expired from one the router explicitly withdrew, yet the two call for
different reactions: an expired RA route means the router failed to
refresh it in time, which points at a misconfigured or unreliable
router and may warrant action such as disabling IPv6 on that network,
while a zero-lifetime withdrawal is normal, RFC-compliant operation.

This is a general problem for any consumer device running Linux,
especially on Wi-Fi networks, where multicast delivery is not
guaranteed (e.g. frames can be lost around DTIM for clients in power
save mode). The motivating case is Android: the userspace NetworkStack
process listens on RTMGRP_IPV6_ROUTE and today treats any loss of the
IPv6 default route as "router lost". To avoid the device repeatedly
gaining and losing IPv6 connectivity on a badly configured network,
when it detects the device is on a dual-stack network with working
IPv4 connectivity, it defensively clears accept_ra_defrtr and restarts
IPv6, so user space apps stop using broken global IPv6 connectivity
while link-local IPv6 keeps working. That reaction is wrong if the
route was withdrawn by a zero-lifetime RA (some ISPs do this
intentionally for reconfiguration) - with accept_ra_defrtr off, IPv6
never recovers once the router advertises again. It is the right
reaction if the route genuinely expired, since the router failed to
refresh it in time.

Fixing this in user space is not practical: RTM_NEWROUTE carries the
initial route lifetime (in rta_cacheinfo), but the kernel does not
resend it when a later RA refreshes the lifetime. So distinguishing
the cause of an RTM_DELROUTE from user space would mean opening a raw
socket, listening to RAs, and tracking lifetimes independently,
duplicating logic the kernel already has. Sending RTM_NEWROUTE on
every RA lifetime refresh was also considered, but that would be
spammy and is technically wrong, since a lifetime update does not add
a new route.

This series proposes RTA_DEL_REASON instead: it tells user space why
the route was deleted so it can react accordingly. In the Android
case, NetworkStack would defensively disable global IPv6 only on
RT_DEL_REASON_EXPIRED, and take no action on
RT_DEL_REASON_RA_WITHDRAWN, since that is RFC-compliant behavior.

Patches 1 to 6 add RTA_DEL_REASON and enum rt_del_reason to the
rtnetlink uAPI, thread the reason from the kernel-initiated IPv6
deletion paths down to the RTM_DELROUTE notification, and record the
cause: RT_DEL_REASON_EXPIRED for routes garbage collected after their
RTF_EXPIRES lifetime ran out, and RT_DEL_REASON_RA_WITHDRAWN for
default routes, prefix routes and RFC 4191 route information routes
withdrawn by Router Advertisements. Patches 1 to 5 are no-ops on the
wire; the attribute first appears in patch 6. The route addition path
is not touched.

Patches 7 to 9 extend the rt-route Netlink spec with the route
notifications and their multicast groups, split the newroute and
delroute request attribute lists out of the shared getroute reply
list, and add the new attribute and its enum.

Only kernel-initiated deletions that user space cannot otherwise
explain are attributed. User-requested deletions are self-explanatory
to the requester, so they carry no reason; the UAPI documents that
absence and RT_DEL_REASON_UNSPEC must be treated identically, which
keeps the door open for attributing more paths (nexthop removal
cascades, device removal) later.

Patch 10 adds selftests covering all three producer paths: a
GC-expired route, and a default route + PIO prefix route + RIO route
advertised and then withdrawn by hand-crafted RAs over a raw ICMPv6
socket (no external RA tool needed), plus a check that user-requested
deletions carry no attribute. The notifications are decoded with YNL,
which also exercises the rt-route spec additions.
====================

Link: https://patch.msgid.link/20260808005642.26901-1-sigefriedhyy@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Paolo Abeni 2026-08-13 12:30:29 +02:00
commit 2f886609bd
11 changed files with 375 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

85
Documentation/netlink/specs/rt-route.yaml
View File

@ -78,6 +78,27 @@ definitions:
-
name: rta-used
type: u32
-
name: del-reason
type: enum
name-prefix: rt-del-reason-
enum-name: rt-del-reason
doc: |
Why the kernel deleted a route. New causes may be appended. The
value space is family-agnostic, a value is never reinterpreted
per address family.
entries:
-
name: unspec
doc: The deletion path does not record a cause.
-
name: expired
doc: The RTF_EXPIRES lifetime ran out and the route was garbage
collected.
-
name: ra-withdrawn
doc: A Router Advertisement withdrew the route with a zero
lifetime.
attribute-sets:
-
@ -185,6 +206,18 @@ attribute-sets:
type: u32
byte-order: big-endian
display-hint: hex
-
name: del-reason
type: u32
enum: del-reason
doc: |
Emitted only on RTM_DELROUTE notifications, and only when the
deletion path records a cause. An absent attribute means
either an older kernel or a deletion path that does not
record its cause, consumers must treat absent and unspec
identically. Currently only IPv6 deletion paths record a
cause. The attribute is notification-only, the kernel rejects
it in requests.
-
name: metrics
name-prefix: rtax-
@ -299,6 +332,7 @@ operations:
- dport
- nh-id
- flowlabel
- del-reason
dump:
request:
value: 26
@ -313,7 +347,35 @@ operations:
do:
request:
value: 24
attributes: *all-route-attrs
attributes: &route-req-attrs
- dst
- src
- iif
- oif
- gateway
- priority
- prefsrc
- metrics
- multipath
- flow
- cacheinfo
- table
- mark
- mfc-stats
- via
- newdst
- pref
- encap-type
- encap
- expires
- pad
- uid
- ttl-propagate
- ip-proto
- sport
- dport
- nh-id
- flowlabel
-
name: delroute
doc: Delete an existing route
@ -321,4 +383,23 @@ operations:
do:
request:
value: 25
attributes: *all-route-attrs
attributes: *route-req-attrs
-
name: newroute-ntf
doc: Notification about a created route.
value: 24
notify: getroute
-
name: delroute-ntf
doc: Notification about a deleted route.
value: 25
notify: getroute
mcast-groups:
list:
-
name: rtnlgrp-ipv4-route
value: 7
-
name: rtnlgrp-ipv6-route
value: 11

5
include/net/ip6_fib.h
View File

@ -468,7 +468,8 @@ void fib6_clean_all_skip_notify(struct net *net,
int fib6_add(struct fib6_node *root, struct fib6_info *rt,
struct nl_info *info, struct netlink_ext_ack *extack);
int fib6_del(struct fib6_info *rt, struct nl_info *info);
int fib6_del(struct fib6_info *rt, struct nl_info *info,
enum rt_del_reason del_reason);
static inline
void rt6_get_prefsrc(const struct rt6_info *rt, struct in6_addr *addr)
@ -532,6 +533,8 @@ static inline void fib6_rt_update(struct net *net, struct fib6_info *rt,
#endif
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int flags);
void inet6_rt_del_notify(struct fib6_info *rt, struct nl_info *info,
enum rt_del_reason del_reason);
void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
unsigned long now);

2
include/net/ip6_route.h
View File

@ -126,6 +126,8 @@ int ipv6_route_ioctl(struct net *net, unsigned int cmd,
int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
struct netlink_ext_ack *extack);
int ip6_ins_rt(struct net *net, struct fib6_info *f6i);
int ip6_del_rt_reason(struct net *net, struct fib6_info *f6i,
enum rt_del_reason del_reason);
#if IS_ENABLED(CONFIG_IPV6)
int ip6_del_rt(struct net *net, struct fib6_info *f6i, bool skip_notify);
#else

25
include/uapi/linux/rtnetlink.h
View File

@ -399,6 +399,7 @@ enum rtattr_type_t {
RTA_DPORT,
RTA_NH_ID,
RTA_FLOWLABEL,
RTA_DEL_REASON,
__RTA_MAX
};
@ -407,6 +408,30 @@ enum rtattr_type_t {
#define RTM_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct rtmsg))))
#define RTM_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct rtmsg))
/* RTA_DEL_REASON: why the kernel deleted the route. u32.
* Emitted only on RTM_DELROUTE notifications, and only when the deletion
* path records a cause. Absence means either an older kernel or a
* deletion path that does not (yet) record its cause - consumers must
* treat "absent" and "unspec" identically. New causes may be appended.
* Currently only IPv6 deletion paths record a cause.
*
* The attribute is notification-only: the kernel rejects it in
* requests, so a notification must not be echoed back verbatim.
*
* The value space is family-agnostic: a value must never be
* reinterpreted per address family. A cause that only one family can
* produce still gets its own value rather than reusing another
* family's.
*/
enum rt_del_reason {
RT_DEL_REASON_UNSPEC, /* cause not recorded */
RT_DEL_REASON_EXPIRED, /* RTF_EXPIRES lifetime ran out (GC) */
RT_DEL_REASON_RA_WITHDRAWN, /* zero-lifetime RA / PIO / RIO */
__RT_DEL_REASON_MAX
};
#define RT_DEL_REASON_MAX (__RT_DEL_REASON_MAX - 1)
/* RTM_MULTIPATH --- array of struct rtnexthop.
*
* "struct rtnexthop" describes all necessary nexthop information,

3
net/ipv6/addrconf.c
View File

@ -2874,7 +2874,8 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
if (rt) {
/* Autoconf prefix route */
if (valid_lft == 0) {
ip6_del_rt(net, rt, false);
ip6_del_rt_reason(net, rt,
RT_DEL_REASON_RA_WITHDRAWN);
rt = NULL;
} else {
table = rt->fib6_table;

14
net/ipv6/ip6_fib.c
View File

@ -1967,7 +1967,8 @@ static struct fib6_node *fib6_repair_tree(struct net *net,
}
static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
struct fib6_info __rcu **rtp, struct nl_info *info)
struct fib6_info __rcu **rtp, struct nl_info *info,
enum rt_del_reason del_reason)
{
struct fib6_info *leaf, *replace_rt = NULL;
struct fib6_walker *w;
@ -2056,13 +2057,14 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn,
call_fib6_entry_notifiers_replace(net, replace_rt);
}
if (!info->skip_notify)
inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
inet6_rt_del_notify(rt, info, del_reason);
fib6_info_release(rt);
}
/* Need to own table->tb6_lock */
int fib6_del(struct fib6_info *rt, struct nl_info *info)
int fib6_del(struct fib6_info *rt, struct nl_info *info,
enum rt_del_reason del_reason)
{
struct net *net = info->nl_net;
struct fib6_info __rcu **rtp;
@ -2091,7 +2093,7 @@ int fib6_del(struct fib6_info *rt, struct nl_info *info)
if (rt == cur) {
if (fib6_requires_src(cur))
fib6_routes_require_src_dec(info->nl_net);
fib6_del_route(table, fn, rtp, info);
fib6_del_route(table, fn, rtp, info, del_reason);
return 0;
}
rtp_next = &cur->fib6_next;
@ -2253,7 +2255,7 @@ static int fib6_clean_node(struct fib6_walker *w)
res = c->func(rt, c->arg);
if (res == -1) {
w->leaf = rt;
res = fib6_del(rt, &info);
res = fib6_del(rt, &info, RT_DEL_REASON_UNSPEC);
if (res) {
#if RT6_DEBUG >= 2
pr_debug("%s: del failed: rt=%p@%p err=%d\n",
@ -2401,7 +2403,7 @@ static void fib6_gc_table(struct net *net,
hlist_for_each_entry_safe(rt, n, &tb6->tb6_gc_hlist, gc_link)
if (fib6_age(rt, gc_args) == -1)
fib6_del(rt, &info);
fib6_del(rt, &info, RT_DEL_REASON_EXPIRED);
}
static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)

4
net/ipv6/ndisc.c
View File

@ -1362,7 +1362,9 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
defrtr_usr_metric = in6_dev->cnf.ra_defrtr_metric;
/* delete the route if lifetime is 0 or if metric needs change */
if (rt && (lifetime == 0 || rt->fib6_metric != defrtr_usr_metric)) {
ip6_del_rt(net, rt, false);
ip6_del_rt_reason(net, rt,
lifetime == 0 ? RT_DEL_REASON_RA_WITHDRAWN :
RT_DEL_REASON_UNSPEC);
rt = NULL;
}

75
net/ipv6/route.c
View File

@ -111,7 +111,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
struct fib6_info *rt, struct dst_entry *dst,
struct in6_addr *dest, struct in6_addr *src,
int iif, int type, u32 portid, u32 seq,
unsigned int flags);
unsigned int flags, enum rt_del_reason del_reason);
static struct rt6_info *rt6_find_cached_rt(const struct fib6_result *res,
const struct in6_addr *daddr,
const struct in6_addr *saddr);
@ -1020,7 +1020,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
gwaddr, dev);
if (rt && !lifetime) {
ip6_del_rt(net, rt, false);
ip6_del_rt_reason(net, rt, RT_DEL_REASON_RA_WITHDRAWN);
rt = NULL;
}
@ -3973,7 +3973,8 @@ int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
return err;
}
static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info)
static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info,
enum rt_del_reason del_reason)
{
struct net *net = info->nl_net;
struct fib6_table *table;
@ -3986,7 +3987,7 @@ static int __ip6_del_rt(struct fib6_info *rt, struct nl_info *info)
table = rt->fib6_table;
spin_lock_bh(&table->tb6_lock);
err = fib6_del(rt, info);
err = fib6_del(rt, info, del_reason);
spin_unlock_bh(&table->tb6_lock);
out:
@ -4001,7 +4002,15 @@ int ip6_del_rt(struct net *net, struct fib6_info *rt, bool skip_notify)
.skip_notify = skip_notify
};
return __ip6_del_rt(rt, &info);
return __ip6_del_rt(rt, &info, RT_DEL_REASON_UNSPEC);
}
int ip6_del_rt_reason(struct net *net, struct fib6_info *rt,
enum rt_del_reason del_reason)
{
struct nl_info info = { .nl_net = net };
return __ip6_del_rt(rt, &info, del_reason);
}
static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
@ -4028,7 +4037,8 @@ static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
if (rt6_fill_node(net, skb, rt, NULL,
NULL, NULL, 0, RTM_DELROUTE,
info->portid, seq, 0) < 0) {
info->portid, seq, 0,
RT_DEL_REASON_UNSPEC) < 0) {
kfree_skb(skb);
skb = NULL;
} else
@ -4064,13 +4074,13 @@ static int __ip6_del_rt_siblings(struct fib6_info *rt, struct fib6_config *cfg)
list_for_each_entry_safe(sibling, next_sibling,
&rt->fib6_siblings,
fib6_siblings) {
err = fib6_del(sibling, info);
err = fib6_del(sibling, info, RT_DEL_REASON_UNSPEC);
if (err)
goto out_unlock;
}
}
err = fib6_del(rt, info);
err = fib6_del(rt, info, RT_DEL_REASON_UNSPEC);
out_unlock:
spin_unlock_bh(&table->tb6_lock);
out_put:
@ -4196,7 +4206,8 @@ static int ip6_route_del(struct fib6_config *cfg,
if (!fib6_info_hold_safe(rt))
continue;
err = __ip6_del_rt(rt, &cfg->fc_nlinfo);
err = __ip6_del_rt(rt, &cfg->fc_nlinfo,
RT_DEL_REASON_UNSPEC);
break;
}
if (cfg->fc_nh_id)
@ -4215,7 +4226,8 @@ static int ip6_route_del(struct fib6_config *cfg,
/* if gateway was specified only delete the one hop */
if (cfg->fc_flags & RTF_GATEWAY)
err = __ip6_del_rt(rt, &cfg->fc_nlinfo);
err = __ip6_del_rt(rt, &cfg->fc_nlinfo,
RT_DEL_REASON_UNSPEC);
else
err = __ip6_del_rt_siblings(rt, cfg);
break;
@ -5739,6 +5751,7 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i)
+ nla_total_size(sizeof(struct rta_cacheinfo))
+ nla_total_size(TCP_CA_NAME_MAX) /* RTAX_CC_ALGO */
+ nla_total_size(1) /* RTA_PREF */
+ nla_total_size(4) /* RTA_DEL_REASON */
+ nexthop_len;
}
@ -5775,7 +5788,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
struct fib6_info *rt, struct dst_entry *dst,
struct in6_addr *dest, struct in6_addr *src,
int iif, int type, u32 portid, u32 seq,
unsigned int flags)
unsigned int flags, enum rt_del_reason del_reason)
{
struct rt6_info *rt6 = dst_rt6_info(dst);
struct rt6key *rt6_dst, *rt6_src;
@ -5954,6 +5967,10 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
if (rtnl_put_cacheinfo(skb, dst, 0, expires, dst ? dst->error : 0) < 0)
goto nla_put_failure;
if (del_reason != RT_DEL_REASON_UNSPEC &&
nla_put_u32(skb, RTA_DEL_REASON, del_reason))
goto nla_put_failure;
if (nla_put_u8(skb, RTA_PREF, IPV6_EXTRACT_PREF(rt6_flags)))
goto nla_put_failure;
@ -6055,7 +6072,8 @@ static int rt6_nh_dump_exceptions(struct fib6_nh *nh, void *arg)
&rt6_ex->rt6i->dst, NULL, NULL, 0,
RTM_NEWROUTE,
NETLINK_CB(dump->cb->skb).portid,
dump->cb->nlh->nlmsg_seq, w->flags);
dump->cb->nlh->nlmsg_seq, w->flags,
RT_DEL_REASON_UNSPEC);
if (err)
return err;
@ -6103,7 +6121,8 @@ int rt6_dump_route(struct fib6_info *rt, void *p_arg, unsigned int skip)
if (rt6_fill_node(net, arg->skb, rt, NULL, NULL, NULL,
0, RTM_NEWROUTE,
NETLINK_CB(arg->cb->skb).portid,
arg->cb->nlh->nlmsg_seq, flags)) {
arg->cb->nlh->nlmsg_seq, flags,
RT_DEL_REASON_UNSPEC)) {
return 0;
}
count++;
@ -6336,12 +6355,14 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
err = rt6_fill_node(net, skb, from, NULL, NULL, NULL,
iif, RTM_NEWROUTE,
NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq, 0);
nlh->nlmsg_seq, 0,
RT_DEL_REASON_UNSPEC);
else
err = rt6_fill_node(net, skb, from, dst, &fl6.daddr,
&fl6.saddr, iif, RTM_NEWROUTE,
NETLINK_CB(in_skb).portid,
nlh->nlmsg_seq, 0);
nlh->nlmsg_seq, 0,
RT_DEL_REASON_UNSPEC);
} else {
err = -ENETUNREACH;
}
@ -6357,8 +6378,9 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
return err;
}
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int nlm_flags)
static void __inet6_rt_notify(int event, struct fib6_info *rt,
struct nl_info *info, unsigned int nlm_flags,
enum rt_del_reason del_reason)
{
struct net *net = info->nl_net;
struct sk_buff *skb;
@ -6377,7 +6399,7 @@ void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
goto errout;
err = rt6_fill_node(net, skb, rt, NULL, NULL, NULL, 0,
event, info->portid, seq, nlm_flags);
event, info->portid, seq, nlm_flags, del_reason);
if (err < 0) {
kfree_skb(skb);
/* -EMSGSIZE implies needed space grew under us. */
@ -6398,6 +6420,18 @@ void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
rtnl_set_sk_err(net, RTNLGRP_IPV6_ROUTE, err);
}
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int nlm_flags)
{
__inet6_rt_notify(event, rt, info, nlm_flags, RT_DEL_REASON_UNSPEC);
}
void inet6_rt_del_notify(struct fib6_info *rt, struct nl_info *info,
enum rt_del_reason del_reason)
{
__inet6_rt_notify(RTM_DELROUTE, rt, info, 0, del_reason);
}
void fib6_rt_update(struct net *net, struct fib6_info *rt,
struct nl_info *info)
{
@ -6410,7 +6444,8 @@ void fib6_rt_update(struct net *net, struct fib6_info *rt,
goto errout;
err = rt6_fill_node(net, skb, rt, NULL, NULL, NULL, 0,
RTM_NEWROUTE, info->portid, seq, NLM_F_REPLACE);
RTM_NEWROUTE, info->portid, seq, NLM_F_REPLACE,
RT_DEL_REASON_UNSPEC);
if (err < 0) {
/* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
WARN_ON(err == -EMSGSIZE);
@ -6463,7 +6498,7 @@ void fib6_info_hw_flags_set(struct net *net, struct fib6_info *f6i,
}
err = rt6_fill_node(net, skb, f6i, NULL, NULL, NULL, 0, RTM_NEWROUTE, 0,
0, 0);
0, 0, RT_DEL_REASON_UNSPEC);
if (err < 0) {
/* -EMSGSIZE implies BUG in rt6_nlmsg_size() */
WARN_ON(err == -EMSGSIZE);

4
tools/testing/selftests/net/lib/py/__init__.py
View File

@ -17,7 +17,7 @@ from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
wait_file, tool, tc
from .bpf import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
from .ynl import NlError, NlctrlFamily, YnlFamily, \
EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily
EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily, RtnlRouteFamily
from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, Netlink
__all__ = ["KSRC",
@ -34,4 +34,4 @@ __all__ = ["KSRC",
"NetdevSim", "NetdevSimDev",
"NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
"YnlFamily", "EthtoolFamily", "NetdevFamily", "RtnlFamily",
"NlctrlFamily", "RtnlAddrFamily", "Netlink"]
"NlctrlFamily", "RtnlAddrFamily", "RtnlRouteFamily", "Netlink"]

7
tools/testing/selftests/net/lib/py/ynl.py
View File

@ -29,7 +29,7 @@ except ModuleNotFoundError as e:
__all__ = [
"NlError", "NlPolicy", "Netlink", "YnlFamily", "SPEC_PATH",
"EthtoolFamily", "RtnlFamily", "RtnlAddrFamily",
"EthtoolFamily", "RtnlFamily", "RtnlAddrFamily", "RtnlRouteFamily",
"NetdevFamily", "NetshaperFamily", "NlctrlFamily", "DevlinkFamily",
"PSPFamily",
]
@ -54,6 +54,11 @@ class RtnlAddrFamily(YnlFamily):
super().__init__((SPEC_PATH / Path('rt-addr.yaml')).as_posix(),
schema='', recv_size=recv_size)
class RtnlRouteFamily(YnlFamily):
def __init__(self, recv_size=0):
super().__init__((SPEC_PATH / Path('rt-route.yaml')).as_posix(),
schema='', recv_size=recv_size)
class NetdevFamily(YnlFamily):
def __init__(self, recv_size=0):
super().__init__((SPEC_PATH / Path('netdev.yaml')).as_posix(),

187
tools/testing/selftests/net/rtnetlink.py
View File

@ -5,7 +5,9 @@ import socket
import struct
import time
from lib.py import bkg, ip, ksft_exit, ksft_run, ksft_eq, ksft_ge, ksft_true, KsftSkipEx
from lib.py import CmdExitFailure, NetNS, NetNSEnter, RtnlAddrFamily
from lib.py import ksft_not_in, ksft_not_none
from lib.py import CmdExitFailure, NetNS, NetNSEnter, RtnlAddrFamily, RtnlRouteFamily
from lib.py import defer
IPV4_ALL_HOSTS_MULTICAST = b'\xe0\x00\x00\x01'
IPV4_TEST_MULTICAST = b'\xef\x01\x01\x01'
@ -134,8 +136,189 @@ def ipv4_devconf_notify() -> None:
ksft_true(f"inet {ifname} forwarding on" in cmd_obj.stdout,
f"No 'forwarding on' notificiation found for interface {ifname}")
def _rtnl_route_subscribe(ns):
with NetNSEnter(str(ns)):
rtnl = RtnlRouteFamily()
defer(rtnl.close)
rtnl.ntf_subscribe("rtnlgrp-ipv6-route")
return rtnl
def _wait_route_ntf(rtnl, name, dst_len, dst=None, deadline=10):
"""Return the attrs of the first matching notification, None on timeout."""
for msg in rtnl.poll_ntf(duration=deadline):
if msg['name'] != name:
continue
attrs = msg['msg']
if attrs['rtm-dst-len'] != dst_len:
continue
if dst is not None and attrs.get('dst') != dst:
continue
return attrs
return None
def _collect_route_ntfs(rtnl, name, want, deadline=10):
"""Gather attrs of matching notifications, keyed by (dst_len, dst)."""
seen = {}
for msg in rtnl.poll_ntf(duration=deadline):
if msg['name'] != name:
continue
attrs = msg['msg']
key = (attrs['rtm-dst-len'], attrs.get('dst'))
if key in want:
seen[key] = attrs
if len(seen) == len(want):
break
return seen
def _write_ipv6_sysctl(name, value):
with open(f"/proc/sys/net/ipv6/{name}", "w") as f:
f.write(f"{value}\n")
def ipv6_route_del_reason_expired() -> None:
"""An expired route reports RTA_DEL_REASON == expired."""
with NetNS() as ns:
rtnl = _rtnl_route_subscribe(ns)
with NetNSEnter(str(ns)):
_write_ipv6_sysctl("route/gc_interval", 2)
ip("link add name dummy1 type dummy", ns=str(ns))
ip("link set dev dummy1 up", ns=str(ns))
ip("-6 route add 2001:db8:2::/64 dev dummy1 expires 2", ns=str(ns))
attrs = _wait_route_ntf(rtnl, 'delroute-ntf', 64, '2001:db8:2::',
deadline=15)
ksft_not_none(attrs, "no RTM_DELROUTE for the expired route")
if attrs is not None:
ksft_eq(attrs.get('del-reason'), 'expired')
def _send_ra(sock, ifindex, lifetime, rio=None, pio=None):
"""The kernel fills in the ICMPv6 checksum on raw ICMPv6 sockets."""
# type, code, cksum, hop limit, flags, router lifetime,
# reachable time, retrans timer
ra = struct.pack('!BBHBBHII', 134, 0, 0, 64, 0, lifetime, 0, 0)
if rio is not None:
prefix, plen, rio_lifetime = rio
# RFC 4191 route information option, /64 prefix (8 bytes)
ra += struct.pack('!BBBBI', 24, 2, plen, 0, rio_lifetime)
ra += socket.inet_pton(socket.AF_INET6, prefix)[:8]
if pio is not None:
prefix, plen, valid_lft = pio
# RFC 4861 prefix information option, on-link only (L set, A clear)
ra += struct.pack('!BBBBIII', 3, 4, plen, 0x80, valid_lft, 0, 0)
ra += socket.inet_pton(socket.AF_INET6, prefix)
sock.sendto(ra, ('ff02::1', 0, 0, ifindex))
def _ra_router_sock(ns_r, ifname):
with NetNSEnter(str(ns_r)):
sock = socket.socket(socket.AF_INET6, socket.SOCK_RAW,
socket.IPPROTO_ICMPV6)
sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, 255)
defer(sock.close)
return sock, socket.if_nametoindex(ifname)
def _ra_advertise_routes(rtnl, sock, ifindex, want, **ra_opts):
"""
Sending fails with EADDRNOTAVAIL while the router's link-local
address is still tentative. addrconf_dad_start() only queues
addrconf_dad_work(), and IFA_F_TENTATIVE is cleared when that work
item runs, so retry until it does.
"""
seen = {}
for _ in range(10):
try:
_send_ra(sock, ifindex, **ra_opts)
except OSError:
time.sleep(0.2)
continue
seen.update(_collect_route_ntfs(rtnl, 'newroute-ntf',
want - set(seen.keys()), deadline=2))
if len(seen) == len(want):
break
return seen
def ipv6_route_del_reason_ra_withdrawn() -> None:
"""
Routes withdrawn by a zero-lifetime RA (router lifetime, RFC 4861
PIO, RFC 4191 RIO) report RTA_DEL_REASON == ra-withdrawn.
"""
# (rtm-dst-len, dst); the default route carries no RTA_DST
routes = {(0, None), (64, '2001:db8:6::'), (64, '2001:db8:5::')}
with NetNS() as ns_h, NetNS() as ns_r:
ip(f"link add veth0 netns {ns_h} type veth peer name veth1 netns {ns_r}")
with NetNSEnter(str(ns_h)):
_write_ipv6_sysctl("conf/veth0/accept_ra", 2)
_write_ipv6_sysctl("conf/veth0/forwarding", 0)
try:
_write_ipv6_sysctl("conf/veth0/accept_ra_rt_info_max_plen", 64)
except FileNotFoundError:
raise KsftSkipEx("no CONFIG_IPV6_ROUTE_INFO")
with NetNSEnter(str(ns_r)):
# skip the DAD probe so the router's link-local source only
# has to wait for addrconf_dad_work() to clear IFA_F_TENTATIVE
_write_ipv6_sysctl("conf/veth1/accept_dad", 0)
ip("link set dev veth0 up", ns=str(ns_h))
ip("link set dev veth1 up", ns=str(ns_r))
rtnl = _rtnl_route_subscribe(ns_h)
sock, ifindex = _ra_router_sock(ns_r, "veth1")
seen = _ra_advertise_routes(rtnl, sock, ifindex, routes,
lifetime=1800,
rio=('2001:db8:5::', 64, 600),
pio=('2001:db8:6::', 64, 600))
ksft_eq(set(seen), routes, "not all RA routes were installed")
if set(seen) != routes:
return
_send_ra(sock, ifindex, 0, rio=('2001:db8:5::', 64, 0),
pio=('2001:db8:6::', 64, 0))
seen = _collect_route_ntfs(rtnl, 'delroute-ntf', routes)
for key in routes:
attrs = seen.get(key)
ksft_not_none(attrs, f"no RTM_DELROUTE for {key}")
if attrs is not None:
ksft_eq(attrs.get('del-reason'), 'ra-withdrawn')
def ipv6_route_del_reason_absent() -> None:
"""
A deletion path that records no cause (here a userspace request)
must not carry RTA_DEL_REASON at all.
"""
with NetNS() as ns:
rtnl = _rtnl_route_subscribe(ns)
ip("link add name dummy1 type dummy", ns=str(ns))
ip("link set dev dummy1 up", ns=str(ns))
ip("-6 route add 2001:db8:1::/64 dev dummy1", ns=str(ns))
ip("-6 route del 2001:db8:1::/64 dev dummy1", ns=str(ns))
attrs = _wait_route_ntf(rtnl, 'delroute-ntf', 64, '2001:db8:1::')
ksft_not_none(attrs, "no RTM_DELROUTE for 2001:db8:1::/64")
if attrs is not None:
ksft_not_in('del-reason', attrs,
"user deletion must not carry del-reason")
def main() -> None:
ksft_run([dump_mcaddr_check, dump_mcaddr6_check, ipv4_devconf_notify])
ksft_run([dump_mcaddr_check, dump_mcaddr6_check, ipv4_devconf_notify,
ipv6_route_del_reason_expired,
ipv6_route_del_reason_ra_withdrawn,
ipv6_route_del_reason_absent])
ksft_exit()
if __name__ == "__main__":