kernel.git/net/ipv4/route.c, branch linux-6.15.y

net: ipv4: fix incorrect MTU in broadcast routes

2025-08-20T16:36:04Z

[ Upstream commit 9e30ecf23b1b8f091f7d08b27968dea83aae7908 ] Currently, __mkroute_output overrules the MTU value configured for broadcast routes. This buggy behaviour can be reproduced with: ip link set dev eth1 mtu 9000 ip route del broadcast 192.168.0.255 dev eth1 proto kernel scope link src 192.168.0.2 ip route add broadcast 192.168.0.255 dev eth1 proto kernel scope link src 192.168.0.2 mtu 1500 The maximum packet size should be 1500, but it is actually 8000: ping -b 192.168.0.255 -s 8000 Fix __mkroute_output to allow MTU values to be configured for for broadcast routes (to support a mixed-MTU local-area-network). Signed-off-by: Oscar Maes Link: https://patch.msgid.link/20250710142714.12986-1-oscmaes92@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: dst: annotate data-races around dst->output

2025-08-15T10:16:27Z

[ Upstream commit 2dce8c52a98995c4719def6f88629ab1581c0b82 ] dst_dev_put() can overwrite dst->output while other cpus might read this field (for instance from dst_output()) Add READ_ONCE()/WRITE_ONCE() annotations to suppress potential issues. We will likely need RCU protection in the future. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-6-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: dst: annotate data-races around dst->input

2025-08-15T10:16:27Z

[ Upstream commit f1c5fd34891a1c242885f48c2e4dc52df180f311 ] dst_dev_put() can overwrite dst->input while other cpus might read this field (for instance from dst_input()) Add READ_ONCE()/WRITE_ONCE() annotations to suppress potential issues. We will likely need full RCU protection later. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv4/route: Use this_cpu_inc() for stats on PREEMPT_RT

2025-06-27T10:13:23Z

[ Upstream commit 1c0829788a6e6e165846b9bedd0b908ef16260b6 ] The statistics are incremented with raw_cpu_inc() assuming it always happens with bottom half disabled. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this is no longer true. Use this_cpu_inc() on PREEMPT_RT for the increment to not worry about preemption. Cc: David Ahern Signed-off-by: Sebastian Andrzej Siewior Link: https://patch.msgid.link/20250512092736.229935-4-bigeasy@linutronix.de Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

ipv4: use RCU protection in __ip_rt_update_pmtu()

2025-02-07T00:14:14Z

__ip_rt_update_pmtu() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: 2fbc6e89b2f1 ("ipv4: Update exception handling for multipath routes via same device") Fixes: 1de6b15a434c ("Namespaceify min_pmtu sysctl") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250205155120.1676781-8-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv4: use RCU protection in rt_is_expired()

2025-02-07T00:14:14Z

rt_is_expired() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: e84f84f27647 ("netns: place rt_genid into struct net") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-6-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv4: use RCU protection in ipv4_default_advmss()

2025-02-07T00:14:14Z

ipv4_default_advmss() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: 2e9589ff809e ("ipv4: Namespaceify min_adv_mss sysctl knob") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-5-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv4: Prepare inet_rtm_getroute() to .flowi4_tos conversion.

2025-01-17T00:52:29Z

Store rtm->rtm_tos in a dscp_t variable, which can then be used for setting fl4.flowi4_tos and also be passed as parameter of ip_route_input_rcu(). The .flowi4_tos field is going to be converted to dscp_t to ensure ECN bits aren't erroneously taken into account during route lookups. Having a dscp_t variable available will simplify that conversion, as we'll just have to drop the inet_dscp_to_dsfield() call. Note that we can't just convert rtm->rtm_tos to dscp_t because this structure is exported to user space. Signed-off-by: Guillaume Nault Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/7bc1c7dc47ad1393569095d334521fae59af5bc7.1736944951.git.gnault@redhat.com Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-01-16T18:34:59Z

Cross-merge networking fixes after downstream PR (net-6.13-rc8). Conflicts: drivers/net/ethernet/realtek/r8169_main.c 1f691a1fc4be ("r8169: remove redundant hwmon support") 152d00a91396 ("r8169: simplify setting hwmon attribute visibility") https://lore.kernel.org/20250115122152.760b4e8d@canb.auug.org.au Adjacent changes: drivers/net/ethernet/broadcom/bnxt/bnxt.c 152f4da05aee ("bnxt_en: add support for rx-copybreak ethtool command") f0aa6a37a3db ("eth: bnxt: always recalculate features after XDP clearing, fix null-deref") drivers/net/ethernet/intel/ice/ice_type.h 50327223a8bb ("ice: add lock to protect low latency interface") dc26548d729e ("ice: Fix quad registers read on E825") Signed-off-by: Jakub Kicinski

ipv4: route: fix drop reason being overridden in ip_route_input_slow

2025-01-10T02:03:24Z

When jumping to 'martian_destination' a drop reason is always set but that label falls-through the 'e_nobufs' one, overriding the value. The behavior was introduced by the mentioned commit. The logic went from, goto martian_destination; ... martian_destination: ... e_inval: err = -EINVAL; goto out; e_nobufs: err = -ENOBUFS; goto out; to, reason = ...; goto martian_destination; ... martian_destination: ... e_nobufs: reason = SKB_DROP_REASON_NOMEM; goto out; A 'goto out' is clearly missing now after 'martian_destination' to avoid overriding the drop reason. Fixes: 5b92112acd8e ("net: ip: make ip_route_input_slow() return drop reasons") Reported-by: Sabrina Dubroca Cc: Menglong Dong Signed-off-by: Antoine Tenart Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250108165725.404564-1-atenart@kernel.org Signed-off-by: Jakub Kicinski