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Date: Mon, 19 Oct 2020 20:57:31 -0600 From: David Ahern <dsahern@...il.com> To: Vincent Bernat <vincent@...nat.ch>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Jonathan Corbet <corbet@....net>, netdev@...r.kernel.org, Andy Gospodarek <andy@...yhouse.net> Subject: Re: [PATCH net-next v1] net: evaluate net.conf.ipvX.all.ignore_routes_with_linkdown [ fix Andy's address ] On 10/17/20 6:50 AM, Vincent Bernat wrote: > Introduced in 0eeb075fad73, the "ignore_routes_with_linkdown" sysctl > ignores a route whose interface is down. It is provided as a > per-interface sysctl. However, while a "all" variant is exposed, it > was a noop since it was never evaluated. We use the usual "or" logic > for this kind of sysctls. > > Tested with: > > ip link add type veth # veth0 + veth1 > ip link add type veth # veth1 + veth2 > ip link set up dev veth0 > ip link set up dev veth1 # link-status paired with veth0 > ip link set up dev veth2 > ip link set up dev veth3 # link-status paired with veth2 > > # First available path > ip -4 addr add 203.0.113.${uts#H}/24 dev veth0 > ip -6 addr add 2001:db8:1::${uts#H}/64 dev veth0 > > # Second available path > ip -4 addr add 192.0.2.${uts#H}/24 dev veth2 > ip -6 addr add 2001:db8:2::${uts#H}/64 dev veth2 > > # More specific route through first path > ip -4 route add 198.51.100.0/25 via 203.0.113.254 # via veth0 > ip -6 route add 2001:db8:3::/56 via 2001:db8:1::ff # via veth0 > > # Less specific route through second path > ip -4 route add 198.51.100.0/24 via 192.0.2.254 # via veth2 > ip -6 route add 2001:db8:3::/48 via 2001:db8:2::ff # via veth2 > > # H1: enable on "all" > # H2: enable on "veth0" > for v in ipv4 ipv6; do > case $uts in > H1) > sysctl -qw net.${v}.conf.all.ignore_routes_with_linkdown=1 > ;; > H2) > sysctl -qw net.${v}.conf.veth0.ignore_routes_with_linkdown=1 > ;; > esac > done > > set -xe > # When veth0 is up, best route is through veth0 > ip -o route get 198.51.100.1 | grep -Fw veth0 > ip -o route get 2001:db8:3::1 | grep -Fw veth0 > > # When veth0 is down, best route should be through veth2 on H1/H2, > # but on veth0 on H2 > ip link set down dev veth1 # down veth0 > ip route show > [ $uts != H3 ] || ip -o route get 198.51.100.1 | grep -Fw veth0 > [ $uts != H3 ] || ip -o route get 2001:db8:3::1 | grep -Fw veth0 > [ $uts = H3 ] || ip -o route get 198.51.100.1 | grep -Fw veth2 > [ $uts = H3 ] || ip -o route get 2001:db8:3::1 | grep -Fw veth2 > > Without this patch, the two last lines would fail on H1 (the one using > the "all" sysctl). With the patch, everything succeeds as expected. > > Also document the sysctl in `ip-sysctl.rst`. > > Fixes: 0eeb075fad73 ("net: ipv4 sysctl option to ignore routes when nexthop link is down") > Signed-off-by: Vincent Bernat <vincent@...nat.ch> > --- > Documentation/networking/ip-sysctl.rst | 3 +++ > include/linux/inetdevice.h | 2 +- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst > index 837d51f9e1fa..fb6e4658fd4f 100644 > --- a/Documentation/networking/ip-sysctl.rst > +++ b/Documentation/networking/ip-sysctl.rst > @@ -1552,6 +1552,9 @@ igmpv3_unsolicited_report_interval - INTEGER > > Default: 1000 (1 seconds) > > +ignore_routes_with_linkdown - BOOLEAN > + Ignore routes whose link is down when performing a FIB lookup. > + > promote_secondaries - BOOLEAN > When a primary IP address is removed from this interface > promote a corresponding secondary IP address instead of > diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h > index 3515ca64e638..3bbcddd22df8 100644 > --- a/include/linux/inetdevice.h > +++ b/include/linux/inetdevice.h > @@ -126,7 +126,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev) > IN_DEV_ORCONF((in_dev), ACCEPT_REDIRECTS))) > > #define IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) \ > - IN_DEV_CONF_GET((in_dev), IGNORE_ROUTES_WITH_LINKDOWN) > + IN_DEV_ORCONF((in_dev), IGNORE_ROUTES_WITH_LINKDOWN) > > #define IN_DEV_ARPFILTER(in_dev) IN_DEV_ORCONF((in_dev), ARPFILTER) > #define IN_DEV_ARP_ACCEPT(in_dev) IN_DEV_ORCONF((in_dev), ARP_ACCEPT) >
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