[PATCH 2/2 net-next] ipv4: ipv4: handle devconf post-set actions on netlink updates
From: Fernando Fernandez Mancera <hidden>
Date: 2026-03-25 16:10:51
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
When IPv4 device configuration parameters are updated via netlink, the kernel currently only updates the value. This bypasses several post-modification actions that occur when these same parameters are updated via sysctl, such as flushing the routing cache or emitting RTM_NEWNETCONF notifications. This patch addresses the inconsistency by calling the devinet_conf_post_set() helper inside inet_set_link_af(). If a flush is required, we defer it until the netlink attribute parsing loop completes. This ensures consistent behavior and side-effects for devconf changes, regardless of whether they are initiated via sysctl or netlink. Signed-off-by: Fernando Fernandez Mancera <redacted> --- net/ipv4/devinet.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index c81bb948d59f..555f85139fb5 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c@@ -2128,11 +2128,16 @@ static int inet_validate_link_af(const struct net_device *dev, return 0; } +static bool devinet_conf_post_set(struct net *net, struct ipv4_devconf *cnf, + int attr, int new, int old, int index); + static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla, struct netlink_ext_ack *extack) { struct in_device *in_dev = __in_dev_get_rtnl(dev); struct nlattr *a, *tb[IFLA_INET_MAX+1]; + struct net *net = dev_net(dev); + bool flush_cache = false; int rem; if (!in_dev)
@@ -2142,8 +2147,17 @@ static int inet_set_link_af(struct net_device *dev, const struct nlattr *nla, return -EINVAL; if (tb[IFLA_INET_CONF]) { - nla_for_each_nested(a, tb[IFLA_INET_CONF], rem) - ipv4_devconf_set(in_dev, nla_type(a), nla_get_u32(a)); + nla_for_each_nested(a, tb[IFLA_INET_CONF], rem) { + int old_value = ipv4_devconf_get(in_dev, nla_type(a)); + int new_value = nla_get_u32(a); + + ipv4_devconf_set(in_dev, nla_type(a), new_value); + if (devinet_conf_post_set(net, &in_dev->cnf, nla_type(a), new_value, + old_value, dev->ifindex)) + flush_cache = true; + } + if (flush_cache) + rt_cache_flush(net); } return 0;
@@ -2507,6 +2521,10 @@ static bool devinet_conf_post_set(struct net *net, struct ipv4_devconf *cnf, return false; switch (attr) { + case IPV4_DEVCONF_FORWARDING: + if (new == 1) + return true; + break; case IPV4_DEVCONF_ROUTE_LOCALNET: case IPV4_DEVCONF_ACCEPT_LOCAL: if (new == 0)
--
2.53.0