diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst | 51 | ||||
| -rw-r--r-- | net/ipv6/addrconf.c | 2 | ||||
| -rw-r--r-- | net/ipv6/ndisc.c | 29 |
3 files changed, 55 insertions, 27 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index b31601405c54..1c3897a4e60f 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -2483,27 +2483,36 @@ drop_unsolicited_na - BOOLEAN By default this is turned off. -accept_untracked_na - BOOLEAN - Add a new neighbour cache entry in STALE state for routers on receiving a - neighbour advertisement (either solicited or unsolicited) with target - link-layer address option specified if no neighbour entry is already - present for the advertised IPv6 address. Without this knob, NAs received - for untracked addresses (absent in neighbour cache) are silently ignored. - - This is as per router-side behaviour documented in RFC9131. - - This has lower precedence than drop_unsolicited_na. - - This will optimize the return path for the initial off-link communication - that is initiated by a directly connected host, by ensuring that - the first-hop router which turns on this setting doesn't have to - buffer the initial return packets to do neighbour-solicitation. - The prerequisite is that the host is configured to send - unsolicited neighbour advertisements on interface bringup. - This setting should be used in conjunction with the ndisc_notify setting - on the host to satisfy this prerequisite. - - By default this is turned off. +accept_untracked_na - INTEGER + Define behavior for accepting neighbor advertisements from devices that + are absent in the neighbor cache: + + - 0 - (default) Do not accept unsolicited and untracked neighbor + advertisements. + + - 1 - Add a new neighbor cache entry in STALE state for routers on + receiving a neighbor advertisement (either solicited or unsolicited) + with target link-layer address option specified if no neighbor entry + is already present for the advertised IPv6 address. Without this knob, + NAs received for untracked addresses (absent in neighbor cache) are + silently ignored. + + This is as per router-side behavior documented in RFC9131. + + This has lower precedence than drop_unsolicited_na. + + This will optimize the return path for the initial off-link + communication that is initiated by a directly connected host, by + ensuring that the first-hop router which turns on this setting doesn't + have to buffer the initial return packets to do neighbor-solicitation. + The prerequisite is that the host is configured to send unsolicited + neighbor advertisements on interface bringup. This setting should be + used in conjunction with the ndisc_notify setting on the host to + satisfy this prerequisite. + + - 2 - Extend option (1) to add a new neighbor cache entry only if the + source IP address is in the same subnet as an address configured on + the interface that received the neighbor advertisement. enhanced_dad - BOOLEAN Include a nonce option in the IPv6 neighbor solicitation messages used for diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 88becb037eb6..6ed807b6c647 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -7042,7 +7042,7 @@ static const struct ctl_table addrconf_sysctl[] = { .data = &ipv6_devconf.accept_untracked_na, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec_minmax, + .proc_handler = proc_dointvec, .extra1 = (void *)SYSCTL_ZERO, .extra2 = (void *)SYSCTL_ONE, }, diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index cd84cbdac0a2..98453693e400 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -967,6 +967,25 @@ out: in6_dev_put(idev); } +static int accept_untracked_na(struct net_device *dev, struct in6_addr *saddr) +{ + struct inet6_dev *idev = __in6_dev_get(dev); + + switch (idev->cnf.accept_untracked_na) { + case 0: /* Don't accept untracked na (absent in neighbor cache) */ + return 0; + case 1: /* Create new entries from na if currently untracked */ + return 1; + case 2: /* Create new entries from untracked na only if saddr is in the + * same subnet as an address configured on the interface that + * received the na + */ + return !!ipv6_chk_prefix(saddr, dev); + default: + return 0; + } +} + static void ndisc_recv_na(struct sk_buff *skb) { struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb); @@ -1061,11 +1080,11 @@ static void ndisc_recv_na(struct sk_buff *skb) * Note that we don't do a (daddr == all-routers-mcast) check. */ new_state = msg->icmph.icmp6_solicited ? NUD_REACHABLE : NUD_STALE; - if (!neigh && lladdr && - idev && idev->cnf.forwarding && - idev->cnf.accept_untracked_na) { - neigh = neigh_create(&nd_tbl, &msg->target, dev); - new_state = NUD_STALE; + if (!neigh && lladdr && idev && idev->cnf.forwarding) { + if (accept_untracked_na(dev, saddr)) { + neigh = neigh_create(&nd_tbl, &msg->target, dev); + new_state = NUD_STALE; + } } if (neigh && !IS_ERR(neigh)) { |