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0eeb075fad
This feature is only enabled with the new per-interface or ipv4 global
sysctls called 'ignore_routes_with_linkdown'.
net.ipv4.conf.all.ignore_routes_with_linkdown = 0
net.ipv4.conf.default.ignore_routes_with_linkdown = 0
net.ipv4.conf.lo.ignore_routes_with_linkdown = 0
...
When the above sysctls are set, will report to userspace that a route is
dead and will no longer resolve to this nexthop when performing a fib
lookup. This will signal to userspace that the route will not be
selected. The signalling of a RTNH_F_DEAD is only passed to userspace
if the sysctl is enabled and link is down. This was done as without it
the netlink listeners would have no idea whether or not a nexthop would
be selected. The kernel only sets RTNH_F_DEAD internally if the
interface has IFF_UP cleared.
With the new sysctl set, the following behavior can be observed
(interface p8p1 is link-down):
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 dead linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1 dead linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
90.0.0.1 via 70.0.0.2 dev p7p1 src 70.0.0.1
cache
local 80.0.0.1 dev lo src 80.0.0.1
cache <local>
80.0.0.2 via 10.0.5.2 dev p9p1 src 10.0.5.15
cache
While the route does remain in the table (so it can be modified if
needed rather than being wiped away as it would be if IFF_UP was
cleared), the proper next-hop is chosen automatically when the link is
down. Now interface p8p1 is linked-up:
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
90.0.0.1 via 80.0.0.2 dev p8p1 src 80.0.0.1
cache
local 80.0.0.1 dev lo src 80.0.0.1
cache <local>
80.0.0.2 dev p8p1 src 80.0.0.1
cache
and the output changes to what one would expect.
If the sysctl is not set, the following output would be expected when
p8p1 is down:
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1 linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
Since the dead flag does not appear, there should be no expectation that
the kernel would skip using this route due to link being down.
v2: Split kernel changes into 2 patches, this actually makes a
behavioral change if the sysctl is set. Also took suggestion from Alex
to simplify code by only checking sysctl during fib lookup and
suggestion from Scott to add a per-interface sysctl.
v3: Code clean-ups to make it more readable and efficient as well as a
reverse path check fix.
v4: Drop binary sysctl
v5: Whitespace fixups from Dave
v6: Style changes from Dave and checkpatch suggestions
v7: One more checkpatch fixup
Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Signed-off-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
Acked-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
357 lines
8.8 KiB
C
357 lines
8.8 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Definitions for the Forwarding Information Base.
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*
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* Authors: A.N.Kuznetsov, <kuznet@ms2.inr.ac.ru>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _NET_IP_FIB_H
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#define _NET_IP_FIB_H
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#include <net/flow.h>
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#include <linux/seq_file.h>
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#include <linux/rcupdate.h>
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#include <net/fib_rules.h>
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#include <net/inetpeer.h>
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#include <linux/percpu.h>
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struct fib_config {
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u8 fc_dst_len;
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u8 fc_tos;
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u8 fc_protocol;
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u8 fc_scope;
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u8 fc_type;
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/* 3 bytes unused */
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u32 fc_table;
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__be32 fc_dst;
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__be32 fc_gw;
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int fc_oif;
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u32 fc_flags;
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u32 fc_priority;
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__be32 fc_prefsrc;
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struct nlattr *fc_mx;
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struct rtnexthop *fc_mp;
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int fc_mx_len;
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int fc_mp_len;
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u32 fc_flow;
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u32 fc_nlflags;
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struct nl_info fc_nlinfo;
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};
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struct fib_info;
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struct rtable;
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struct fib_nh_exception {
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struct fib_nh_exception __rcu *fnhe_next;
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int fnhe_genid;
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__be32 fnhe_daddr;
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u32 fnhe_pmtu;
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__be32 fnhe_gw;
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unsigned long fnhe_expires;
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struct rtable __rcu *fnhe_rth_input;
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struct rtable __rcu *fnhe_rth_output;
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unsigned long fnhe_stamp;
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};
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struct fnhe_hash_bucket {
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struct fib_nh_exception __rcu *chain;
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};
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#define FNHE_HASH_SHIFT 11
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#define FNHE_HASH_SIZE (1 << FNHE_HASH_SHIFT)
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#define FNHE_RECLAIM_DEPTH 5
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struct fib_nh {
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struct net_device *nh_dev;
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struct hlist_node nh_hash;
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struct fib_info *nh_parent;
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unsigned int nh_flags;
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unsigned char nh_scope;
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int nh_weight;
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int nh_power;
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#endif
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#ifdef CONFIG_IP_ROUTE_CLASSID
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__u32 nh_tclassid;
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#endif
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int nh_oif;
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__be32 nh_gw;
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__be32 nh_saddr;
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int nh_saddr_genid;
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struct rtable __rcu * __percpu *nh_pcpu_rth_output;
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struct rtable __rcu *nh_rth_input;
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struct fnhe_hash_bucket __rcu *nh_exceptions;
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};
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/*
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* This structure contains data shared by many of routes.
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*/
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struct fib_info {
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struct hlist_node fib_hash;
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struct hlist_node fib_lhash;
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struct net *fib_net;
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int fib_treeref;
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atomic_t fib_clntref;
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unsigned int fib_flags;
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unsigned char fib_dead;
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unsigned char fib_protocol;
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unsigned char fib_scope;
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unsigned char fib_type;
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__be32 fib_prefsrc;
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u32 fib_priority;
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u32 *fib_metrics;
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#define fib_mtu fib_metrics[RTAX_MTU-1]
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#define fib_window fib_metrics[RTAX_WINDOW-1]
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#define fib_rtt fib_metrics[RTAX_RTT-1]
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#define fib_advmss fib_metrics[RTAX_ADVMSS-1]
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int fib_nhs;
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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int fib_power;
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#endif
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struct rcu_head rcu;
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struct fib_nh fib_nh[0];
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#define fib_dev fib_nh[0].nh_dev
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};
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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struct fib_rule;
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#endif
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struct fib_table;
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struct fib_result {
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unsigned char prefixlen;
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unsigned char nh_sel;
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unsigned char type;
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unsigned char scope;
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u32 tclassid;
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struct fib_info *fi;
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struct fib_table *table;
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struct hlist_head *fa_head;
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};
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struct fib_result_nl {
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__be32 fl_addr; /* To be looked up*/
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u32 fl_mark;
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unsigned char fl_tos;
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unsigned char fl_scope;
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unsigned char tb_id_in;
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unsigned char tb_id; /* Results */
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unsigned char prefixlen;
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unsigned char nh_sel;
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unsigned char type;
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unsigned char scope;
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int err;
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};
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#ifdef CONFIG_IP_ROUTE_MULTIPATH
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#define FIB_RES_NH(res) ((res).fi->fib_nh[(res).nh_sel])
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#else /* CONFIG_IP_ROUTE_MULTIPATH */
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#define FIB_RES_NH(res) ((res).fi->fib_nh[0])
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#endif /* CONFIG_IP_ROUTE_MULTIPATH */
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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#define FIB_TABLE_HASHSZ 256
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#else
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#define FIB_TABLE_HASHSZ 2
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#endif
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__be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh);
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#define FIB_RES_SADDR(net, res) \
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((FIB_RES_NH(res).nh_saddr_genid == \
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atomic_read(&(net)->ipv4.dev_addr_genid)) ? \
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FIB_RES_NH(res).nh_saddr : \
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fib_info_update_nh_saddr((net), &FIB_RES_NH(res)))
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#define FIB_RES_GW(res) (FIB_RES_NH(res).nh_gw)
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#define FIB_RES_DEV(res) (FIB_RES_NH(res).nh_dev)
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#define FIB_RES_OIF(res) (FIB_RES_NH(res).nh_oif)
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#define FIB_RES_PREFSRC(net, res) ((res).fi->fib_prefsrc ? : \
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FIB_RES_SADDR(net, res))
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struct fib_table {
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struct hlist_node tb_hlist;
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u32 tb_id;
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int tb_default;
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int tb_num_default;
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struct rcu_head rcu;
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unsigned long *tb_data;
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unsigned long __data[0];
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};
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int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
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struct fib_result *res, int fib_flags);
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int fib_table_insert(struct fib_table *, struct fib_config *);
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int fib_table_delete(struct fib_table *, struct fib_config *);
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int fib_table_dump(struct fib_table *table, struct sk_buff *skb,
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struct netlink_callback *cb);
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int fib_table_flush(struct fib_table *table);
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struct fib_table *fib_trie_unmerge(struct fib_table *main_tb);
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void fib_table_flush_external(struct fib_table *table);
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void fib_free_table(struct fib_table *tb);
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#ifndef CONFIG_IP_MULTIPLE_TABLES
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#define TABLE_LOCAL_INDEX (RT_TABLE_LOCAL & (FIB_TABLE_HASHSZ - 1))
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#define TABLE_MAIN_INDEX (RT_TABLE_MAIN & (FIB_TABLE_HASHSZ - 1))
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static inline struct fib_table *fib_get_table(struct net *net, u32 id)
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{
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struct hlist_node *tb_hlist;
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struct hlist_head *ptr;
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ptr = id == RT_TABLE_LOCAL ?
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&net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX] :
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&net->ipv4.fib_table_hash[TABLE_MAIN_INDEX];
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tb_hlist = rcu_dereference_rtnl(hlist_first_rcu(ptr));
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return hlist_entry(tb_hlist, struct fib_table, tb_hlist);
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}
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static inline struct fib_table *fib_new_table(struct net *net, u32 id)
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{
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return fib_get_table(net, id);
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}
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static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
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struct fib_result *res, unsigned int flags)
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{
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struct fib_table *tb;
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int err = -ENETUNREACH;
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rcu_read_lock();
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tb = fib_get_table(net, RT_TABLE_MAIN);
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if (tb && !fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF))
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err = 0;
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rcu_read_unlock();
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return err;
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}
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#else /* CONFIG_IP_MULTIPLE_TABLES */
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int __net_init fib4_rules_init(struct net *net);
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void __net_exit fib4_rules_exit(struct net *net);
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struct fib_table *fib_new_table(struct net *net, u32 id);
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struct fib_table *fib_get_table(struct net *net, u32 id);
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int __fib_lookup(struct net *net, struct flowi4 *flp,
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struct fib_result *res, unsigned int flags);
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static inline int fib_lookup(struct net *net, struct flowi4 *flp,
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struct fib_result *res, unsigned int flags)
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{
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struct fib_table *tb;
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int err;
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flags |= FIB_LOOKUP_NOREF;
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if (net->ipv4.fib_has_custom_rules)
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return __fib_lookup(net, flp, res, flags);
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rcu_read_lock();
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res->tclassid = 0;
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for (err = 0; !err; err = -ENETUNREACH) {
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tb = rcu_dereference_rtnl(net->ipv4.fib_main);
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if (tb && !fib_table_lookup(tb, flp, res, flags))
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break;
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tb = rcu_dereference_rtnl(net->ipv4.fib_default);
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if (tb && !fib_table_lookup(tb, flp, res, flags))
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break;
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}
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rcu_read_unlock();
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return err;
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}
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#endif /* CONFIG_IP_MULTIPLE_TABLES */
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/* Exported by fib_frontend.c */
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extern const struct nla_policy rtm_ipv4_policy[];
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void ip_fib_init(void);
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__be32 fib_compute_spec_dst(struct sk_buff *skb);
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int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
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u8 tos, int oif, struct net_device *dev,
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struct in_device *idev, u32 *itag);
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void fib_select_default(struct fib_result *res);
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#ifdef CONFIG_IP_ROUTE_CLASSID
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static inline int fib_num_tclassid_users(struct net *net)
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{
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return net->ipv4.fib_num_tclassid_users;
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}
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#else
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static inline int fib_num_tclassid_users(struct net *net)
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{
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return 0;
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}
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#endif
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int fib_unmerge(struct net *net);
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void fib_flush_external(struct net *net);
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/* Exported by fib_semantics.c */
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int ip_fib_check_default(__be32 gw, struct net_device *dev);
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int fib_sync_down_dev(struct net_device *dev, unsigned long event);
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int fib_sync_down_addr(struct net *net, __be32 local);
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int fib_sync_up(struct net_device *dev, unsigned int nh_flags);
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void fib_select_multipath(struct fib_result *res);
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/* Exported by fib_trie.c */
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void fib_trie_init(void);
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struct fib_table *fib_trie_table(u32 id, struct fib_table *alias);
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static inline void fib_combine_itag(u32 *itag, const struct fib_result *res)
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{
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#ifdef CONFIG_IP_ROUTE_CLASSID
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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u32 rtag;
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#endif
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*itag = FIB_RES_NH(*res).nh_tclassid<<16;
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#ifdef CONFIG_IP_MULTIPLE_TABLES
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rtag = res->tclassid;
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if (*itag == 0)
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*itag = (rtag<<16);
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*itag |= (rtag>>16);
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#endif
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#endif
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}
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void free_fib_info(struct fib_info *fi);
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static inline void fib_info_put(struct fib_info *fi)
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{
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if (atomic_dec_and_test(&fi->fib_clntref))
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free_fib_info(fi);
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}
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#ifdef CONFIG_PROC_FS
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int __net_init fib_proc_init(struct net *net);
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void __net_exit fib_proc_exit(struct net *net);
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#else
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static inline int fib_proc_init(struct net *net)
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{
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return 0;
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}
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static inline void fib_proc_exit(struct net *net)
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{
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}
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#endif
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#endif /* _NET_FIB_H */
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