From 2d300ce0b783ba74420052ed3a12010ac93bdb08 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 14 Apr 2025 20:20:21 +0300 Subject: [PATCH] net: fib_rules: Fix iif / oif matching on L3 master device Before commit 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices") it was possible to use FIB rules to match on a L3 domain. This was done by having a FIB rule match on iif / oif being a L3 master device. It worked because prior to the FIB rule lookup the iif / oif fields in the flow structure were reset to the index of the L3 master device to which the input / output device was enslaved to. The above scheme made it impossible to match on the original input / output device. Therefore, cited commit stopped overwriting the iif / oif fields in the flow structure and instead stored the index of the enslaving L3 master device in a new field ('flowi_l3mdev') in the flow structure. While the change enabled new use cases, it broke the original use case of matching on a L3 domain. Fix this by interpreting the iif / oif matching on a L3 master device as a match against the L3 domain. In other words, if the iif / oif in the FIB rule points to a L3 master device, compare the provided index against 'flowi_l3mdev' rather than 'flowi_{i,o}if'. Before cited commit, a FIB rule that matched on 'iif vrf1' would only match incoming traffic from devices enslaved to 'vrf1'. With the proposed change (i.e., comparing against 'flowi_l3mdev'), the rule would also match traffic originating from a socket bound to 'vrf1'. Avoid that by adding a new flow flag ('FLOWI_FLAG_L3MDEV_OIF') that indicates if the L3 domain was derived from the output interface or the input interface (when not set) and take this flag into account when evaluating the FIB rule against the flow structure. Avoid unnecessary checks in the data path by detecting that a rule matches on a L3 master device when the rule is installed and marking it as such. Tested using the following script [1]. Output before 40867d74c374 (v5.4.291): default dev dummy1 table 100 scope link default dev dummy1 table 200 scope link Output after 40867d74c374: default dev dummy1 table 300 scope link default dev dummy1 table 300 scope link Output with this patch: default dev dummy1 table 100 scope link default dev dummy1 table 200 scope link [1] #!/bin/bash ip link add name vrf1 up type vrf table 10 ip link add name dummy1 up master vrf1 type dummy sysctl -wq net.ipv4.conf.all.forwarding=1 sysctl -wq net.ipv4.conf.all.rp_filter=0 ip route add table 100 default dev dummy1 ip route add table 200 default dev dummy1 ip route add table 300 default dev dummy1 ip rule add prio 0 oif vrf1 table 100 ip rule add prio 1 iif vrf1 table 200 ip rule add prio 2 table 300 ip route get 192.0.2.1 oif dummy1 fibmatch ip route get 192.0.2.1 iif dummy1 from 198.51.100.1 fibmatch Fixes: 40867d74c374 ("net: Add l3mdev index to flow struct and avoid oif reset for port devices") Reported-by: hanhuihui Closes: https://lore.kernel.org/netdev/ec671c4f821a4d63904d0da15d604b75@huawei.com/ Signed-off-by: Ido Schimmel Acked-by: David Ahern Link: https://patch.msgid.link/20250414172022.242991-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski --- include/net/fib_rules.h | 2 ++ include/net/flow.h | 1 + include/net/l3mdev.h | 27 +++++++++++++++++++++++ net/core/fib_rules.c | 48 ++++++++++++++++++++++++++++++++++------- net/l3mdev/l3mdev.c | 4 +++- 5 files changed, 73 insertions(+), 9 deletions(-) diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h index 5927910ec06e5..6e68e359ad18c 100644 --- a/include/net/fib_rules.h +++ b/include/net/fib_rules.h @@ -45,6 +45,8 @@ struct fib_rule { struct fib_rule_port_range dport_range; u16 sport_mask; u16 dport_mask; + u8 iif_is_l3_master; + u8 oif_is_l3_master; struct rcu_head rcu; }; diff --git a/include/net/flow.h b/include/net/flow.h index 335bbc52171c1..2a3f0c42f0925 100644 --- a/include/net/flow.h +++ b/include/net/flow.h @@ -38,6 +38,7 @@ struct flowi_common { __u8 flowic_flags; #define FLOWI_FLAG_ANYSRC 0x01 #define FLOWI_FLAG_KNOWN_NH 0x02 +#define FLOWI_FLAG_L3MDEV_OIF 0x04 __u32 flowic_secid; kuid_t flowic_uid; __u32 flowic_multipath_hash; diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h index f7fe796e8429a..1eb8dad18f7e3 100644 --- a/include/net/l3mdev.h +++ b/include/net/l3mdev.h @@ -59,6 +59,20 @@ int l3mdev_ifindex_lookup_by_table_id(enum l3mdev_type l3type, struct net *net, int l3mdev_fib_rule_match(struct net *net, struct flowi *fl, struct fib_lookup_arg *arg); +static inline +bool l3mdev_fib_rule_iif_match(const struct flowi *fl, int iifindex) +{ + return !(fl->flowi_flags & FLOWI_FLAG_L3MDEV_OIF) && + fl->flowi_l3mdev == iifindex; +} + +static inline +bool l3mdev_fib_rule_oif_match(const struct flowi *fl, int oifindex) +{ + return fl->flowi_flags & FLOWI_FLAG_L3MDEV_OIF && + fl->flowi_l3mdev == oifindex; +} + void l3mdev_update_flow(struct net *net, struct flowi *fl); int l3mdev_master_ifindex_rcu(const struct net_device *dev); @@ -327,6 +341,19 @@ int l3mdev_fib_rule_match(struct net *net, struct flowi *fl, { return 1; } + +static inline +bool l3mdev_fib_rule_iif_match(const struct flowi *fl, int iifindex) +{ + return false; +} + +static inline +bool l3mdev_fib_rule_oif_match(const struct flowi *fl, int oifindex) +{ + return false; +} + static inline void l3mdev_update_flow(struct net *net, struct flowi *fl) { diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c index 4bc64d912a1c0..7af302080a660 100644 --- a/net/core/fib_rules.c +++ b/net/core/fib_rules.c @@ -257,6 +257,24 @@ static int nla_put_port_range(struct sk_buff *skb, int attrtype, return nla_put(skb, attrtype, sizeof(*range), range); } +static bool fib_rule_iif_match(const struct fib_rule *rule, int iifindex, + const struct flowi *fl) +{ + u8 iif_is_l3_master = READ_ONCE(rule->iif_is_l3_master); + + return iif_is_l3_master ? l3mdev_fib_rule_iif_match(fl, iifindex) : + fl->flowi_iif == iifindex; +} + +static bool fib_rule_oif_match(const struct fib_rule *rule, int oifindex, + const struct flowi *fl) +{ + u8 oif_is_l3_master = READ_ONCE(rule->oif_is_l3_master); + + return oif_is_l3_master ? l3mdev_fib_rule_oif_match(fl, oifindex) : + fl->flowi_oif == oifindex; +} + static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops, struct flowi *fl, int flags, struct fib_lookup_arg *arg) @@ -264,11 +282,11 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops, int iifindex, oifindex, ret = 0; iifindex = READ_ONCE(rule->iifindex); - if (iifindex && (iifindex != fl->flowi_iif)) + if (iifindex && !fib_rule_iif_match(rule, iifindex, fl)) goto out; oifindex = READ_ONCE(rule->oifindex); - if (oifindex && (oifindex != fl->flowi_oif)) + if (oifindex && !fib_rule_oif_match(rule, oifindex, fl)) goto out; if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask) @@ -736,16 +754,20 @@ static int fib_nl2rule_rtnl(struct fib_rule *nlrule, struct net_device *dev; dev = __dev_get_by_name(nlrule->fr_net, nlrule->iifname); - if (dev) + if (dev) { nlrule->iifindex = dev->ifindex; + nlrule->iif_is_l3_master = netif_is_l3_master(dev); + } } if (tb[FRA_OIFNAME]) { struct net_device *dev; dev = __dev_get_by_name(nlrule->fr_net, nlrule->oifname); - if (dev) + if (dev) { nlrule->oifindex = dev->ifindex; + nlrule->oif_is_l3_master = netif_is_l3_master(dev); + } } return 0; @@ -1336,11 +1358,17 @@ static void attach_rules(struct list_head *rules, struct net_device *dev) list_for_each_entry(rule, rules, list) { if (rule->iifindex == -1 && - strcmp(dev->name, rule->iifname) == 0) + strcmp(dev->name, rule->iifname) == 0) { WRITE_ONCE(rule->iifindex, dev->ifindex); + WRITE_ONCE(rule->iif_is_l3_master, + netif_is_l3_master(dev)); + } if (rule->oifindex == -1 && - strcmp(dev->name, rule->oifname) == 0) + strcmp(dev->name, rule->oifname) == 0) { WRITE_ONCE(rule->oifindex, dev->ifindex); + WRITE_ONCE(rule->oif_is_l3_master, + netif_is_l3_master(dev)); + } } } @@ -1349,10 +1377,14 @@ static void detach_rules(struct list_head *rules, struct net_device *dev) struct fib_rule *rule; list_for_each_entry(rule, rules, list) { - if (rule->iifindex == dev->ifindex) + if (rule->iifindex == dev->ifindex) { WRITE_ONCE(rule->iifindex, -1); - if (rule->oifindex == dev->ifindex) + WRITE_ONCE(rule->iif_is_l3_master, false); + } + if (rule->oifindex == dev->ifindex) { WRITE_ONCE(rule->oifindex, -1); + WRITE_ONCE(rule->oif_is_l3_master, false); + } } } diff --git a/net/l3mdev/l3mdev.c b/net/l3mdev/l3mdev.c index ca10916340b09..5432a5f2dfc8a 100644 --- a/net/l3mdev/l3mdev.c +++ b/net/l3mdev/l3mdev.c @@ -277,8 +277,10 @@ void l3mdev_update_flow(struct net *net, struct flowi *fl) if (fl->flowi_oif) { dev = dev_get_by_index_rcu(net, fl->flowi_oif); if (dev) { - if (!fl->flowi_l3mdev) + if (!fl->flowi_l3mdev) { fl->flowi_l3mdev = l3mdev_master_ifindex_rcu(dev); + fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF; + } /* oif set to L3mdev directs lookup to its table; * reset to avoid oif match in fib_lookup