From 47f0bd5032106469827cf56c8b45bb9101112105 Mon Sep 17 00:00:00 2001 From: Jacques de Laval Date: Thu, 17 Feb 2022 16:02:02 +0100 Subject: net: Add new protocol attribute to IP addresses This patch adds a new protocol attribute to IPv4 and IPv6 addresses. Inspiration was taken from the protocol attribute of routes. User space applications like iproute2 can set/get the protocol with the Netlink API. The attribute is stored as an 8-bit unsigned integer. The protocol attribute is set by kernel for these categories: - IPv4 and IPv6 loopback addresses - IPv6 addresses generated from router announcements - IPv6 link local addresses User space may pass custom protocols, not defined by the kernel. Grouping addresses on their origin is useful in scenarios where you want to distinguish between addresses based on who added them, e.g. kernel vs. user space. Tagging addresses with a string label is an existing feature that could be used as a solution. Unfortunately the max length of a label is 15 characters, and for compatibility reasons the label must be prefixed with the name of the device followed by a colon. Since device names also have a max length of 15 characters, only -1 characters is guaranteed to be available for any origin tag, which is not that much. A reference implementation of user space setting and getting protocols is available for iproute2: https://github.com/westermo/iproute2/commit/9a6ea18bd79f47f293e5edc7780f315ea42ff540 Signed-off-by: Jacques de Laval Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20220217150202.80802-1-Jacques.De.Laval@westermo.com Signed-off-by: Jakub Kicinski --- include/linux/inetdevice.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/inetdevice.h') diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h index 674aeead6260..ead323243e7b 100644 --- a/include/linux/inetdevice.h +++ b/include/linux/inetdevice.h @@ -150,6 +150,7 @@ struct in_ifaddr { __be32 ifa_broadcast; unsigned char ifa_scope; unsigned char ifa_prefixlen; + unsigned char ifa_proto; __u32 ifa_flags; char ifa_label[IFNAMSIZ]; -- cgit v1.2.3 From e68c5dcf0aacc48a23cedcb3ce81b8c60837f48c Mon Sep 17 00:00:00 2001 From: Jaehee Park Date: Wed, 13 Jul 2022 16:40:47 -0700 Subject: net: ipv4: new arp_accept option to accept garp only if in-network In many deployments, we want the option to not learn a neighbor from garp if the src ip is not in the same subnet as an address configured on the interface that received the garp message. net.ipv4.arp_accept sysctl is currently used to control creation of a neigh from a received garp packet. This patch adds a new option '2' to net.ipv4.arp_accept which extends option '1' by including the subnet check. Signed-off-by: Jaehee Park Suggested-by: Roopa Prabhu Signed-off-by: Jakub Kicinski --- Documentation/networking/ip-sysctl.rst | 9 ++++++--- include/linux/inetdevice.h | 2 +- net/ipv4/arp.c | 24 ++++++++++++++++++++++-- 3 files changed, 29 insertions(+), 6 deletions(-) (limited to 'include/linux/inetdevice.h') diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 2b329042b38c..b31601405c54 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1633,12 +1633,15 @@ arp_notify - BOOLEAN or hardware address changes. == ========================================================== -arp_accept - BOOLEAN - Define behavior for gratuitous ARP frames who's IP is not - already present in the ARP table: +arp_accept - INTEGER + Define behavior for accepting gratuitous ARP (garp) frames from devices + that are not already present in the ARP table: - 0 - don't create new entries in the ARP table - 1 - create new entries in the ARP table + - 2 - create new entries only if the source IP address is in the same + subnet as an address configured on the interface that received the + garp message. Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on. diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h index ead323243e7b..ddb27fc0ee8c 100644 --- a/include/linux/inetdevice.h +++ b/include/linux/inetdevice.h @@ -131,7 +131,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev) 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) +#define IN_DEV_ARP_ACCEPT(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ACCEPT) #define IN_DEV_ARP_ANNOUNCE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE) #define IN_DEV_ARP_IGNORE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_IGNORE) #define IN_DEV_ARP_NOTIFY(in_dev) IN_DEV_MAXCONF((in_dev), ARP_NOTIFY) diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index af2f12ffc9ca..87c7e3fc5197 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -429,6 +429,26 @@ static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip) return !inet_confirm_addr(net, in_dev, sip, tip, scope); } +static int arp_accept(struct in_device *in_dev, __be32 sip) +{ + struct net *net = dev_net(in_dev->dev); + int scope = RT_SCOPE_LINK; + + switch (IN_DEV_ARP_ACCEPT(in_dev)) { + case 0: /* Don't create new entries from garp */ + return 0; + case 1: /* Create new entries from garp */ + return 1; + case 2: /* Create a neighbor in the arp table only if sip + * is in the same subnet as an address configured + * on the interface that received the garp message + */ + return !!inet_confirm_addr(net, in_dev, sip, 0, scope); + default: + return 0; + } +} + static int arp_filter(__be32 sip, __be32 tip, struct net_device *dev) { struct rtable *rt; @@ -868,12 +888,12 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb) n = __neigh_lookup(&arp_tbl, &sip, dev, 0); addr_type = -1; - if (n || IN_DEV_ARP_ACCEPT(in_dev)) { + if (n || arp_accept(in_dev, sip)) { is_garp = arp_is_garp(net, dev, &addr_type, arp->ar_op, sip, tip, sha, tha); } - if (IN_DEV_ARP_ACCEPT(in_dev)) { + if (arp_accept(in_dev, sip)) { /* Unsolicited ARP is not accepted by default. It is possible, that this option should be enabled for some devices (strip is candidate) -- cgit v1.2.3