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| author | xu xin <xu.xin16@zte.com.cn> | 2024-05-14 20:11:02 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2024-05-16 19:31:15 -0700 |
| commit | bb487272380d120295e955ad8acfcbb281b57642 (patch) | |
| tree | d9ce1d19cca011360b783e4571f949851cf1ca14 /net/ipv6 | |
| parent | 988af276360bc555c7685d5a607d4da0588616d9 (diff) | |
| download | linux-bb487272380d120295e955ad8acfcbb281b57642.tar.gz linux-bb487272380d120295e955ad8acfcbb281b57642.tar.bz2 linux-bb487272380d120295e955ad8acfcbb281b57642.zip | |
net/ipv6: Fix route deleting failure when metric equals 0
Problem
=========
After commit 67f695134703 ("ipv6: Move setting default metric for routes"),
we noticed that the logic of assigning the default value of fc_metirc
changed in the ioctl process. That is, when users use ioctl(fd, SIOCADDRT,
rt) with a non-zero metric to add a route, then they may fail to delete a
route with passing in a metric value of 0 to the kernel by ioctl(fd,
SIOCDELRT, rt). But iproute can succeed in deleting it.
As a reference, when using iproute tools by netlink to delete routes with
a metric parameter equals 0, like the command as follows:
ip -6 route del fe80::/64 via fe81::5054:ff:fe11:3451 dev eth0 metric 0
the user can still succeed in deleting the route entry with the smallest
metric.
Root Reason
===========
After commit 67f695134703 ("ipv6: Move setting default metric for routes"),
When ioctl() pass in SIOCDELRT with a zero metric, rtmsg_to_fib6_config()
will set a defalut value (1024) to cfg->fc_metric in kernel, and in
ip6_route_del() and the line 4074 at net/ipv3/route.c, it will check by
if (cfg->fc_metric && cfg->fc_metric != rt->fib6_metric)
continue;
and the condition is true and skip the later procedure (deleting route)
because cfg->fc_metric != rt->fib6_metric. But before that commit,
cfg->fc_metric is still zero there, so the condition is false and it
will do the following procedure (deleting).
Solution
========
In order to keep a consistent behaviour across netlink() and ioctl(), we
should allow to delete a route with a metric value of 0. So we only do
the default setting of fc_metric in route adding.
CC: stable@vger.kernel.org # 5.4+
Fixes: 67f695134703 ("ipv6: Move setting default metric for routes")
Co-developed-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240514201102055dD2Ba45qKbLlUMxu_DTHP@zte.com.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/route.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index c43b0616742e..bbc2a0dd9314 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -4445,7 +4445,7 @@ static void rtmsg_to_fib6_config(struct net *net, .fc_table = l3mdev_fib_table_by_index(net, rtmsg->rtmsg_ifindex) ? : RT6_TABLE_MAIN, .fc_ifindex = rtmsg->rtmsg_ifindex, - .fc_metric = rtmsg->rtmsg_metric ? : IP6_RT_PRIO_USER, + .fc_metric = rtmsg->rtmsg_metric, .fc_expires = rtmsg->rtmsg_info, .fc_dst_len = rtmsg->rtmsg_dst_len, .fc_src_len = rtmsg->rtmsg_src_len, @@ -4475,6 +4475,9 @@ int ipv6_route_ioctl(struct net *net, unsigned int cmd, struct in6_rtmsg *rtmsg) rtnl_lock(); switch (cmd) { case SIOCADDRT: + /* Only do the default setting of fc_metric in route adding */ + if (cfg.fc_metric == 0) + cfg.fc_metric = IP6_RT_PRIO_USER; err = ip6_route_add(&cfg, GFP_KERNEL, NULL); break; case SIOCDELRT: |