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![Eric W. Biederman](/assets/img/avatar_default.png)
When I was fixing issues with unregisgtering tables under /proc/sys/net/ipv6/neigh by adding a mount point it appears I missed a critical ordering issue, in the ipv6 initialization. I had not realized that ipv6_sysctl_register is called at the very end of the ipv6 initialization and in particular after we call neigh_sysctl_register from ndisc_init. "neigh" needs to be initialized in ipv6_static_sysctl_register which is the first ipv6 table to initialized, and definitely before ndisc_init. This removes the weirdness of duplicate tables while still providing a "neigh" mount point which prevents races in sysctl unregistering. This was initially reported at https://bugzilla.kernel.org/show_bug.cgi?id=31232 Reported-by: sunkan@zappa.cx Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
176 lines
3.5 KiB
C
176 lines
3.5 KiB
C
/*
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* sysctl_net_ipv6.c: sysctl interface to net IPV6 subsystem.
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*
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* Changes:
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* YOSHIFUJI Hideaki @USAGI: added icmp sysctl table.
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*/
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#include <linux/mm.h>
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#include <linux/sysctl.h>
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#include <linux/in6.h>
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#include <linux/ipv6.h>
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#include <linux/slab.h>
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#include <net/ndisc.h>
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#include <net/ipv6.h>
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#include <net/addrconf.h>
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#include <net/inet_frag.h>
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static struct ctl_table empty[1];
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static ctl_table ipv6_static_skeleton[] = {
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{
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.procname = "neigh",
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.maxlen = 0,
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.mode = 0555,
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.child = empty,
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},
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{ }
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};
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static ctl_table ipv6_table_template[] = {
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{
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.procname = "route",
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.maxlen = 0,
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.mode = 0555,
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.child = ipv6_route_table_template
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},
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{
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.procname = "icmp",
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.maxlen = 0,
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.mode = 0555,
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.child = ipv6_icmp_table_template
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},
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{
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.procname = "bindv6only",
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.data = &init_net.ipv6.sysctl.bindv6only,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{ }
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};
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static ctl_table ipv6_rotable[] = {
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{
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.procname = "mld_max_msf",
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.data = &sysctl_mld_max_msf,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{ }
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};
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struct ctl_path net_ipv6_ctl_path[] = {
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{ .procname = "net", },
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{ .procname = "ipv6", },
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{ },
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};
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EXPORT_SYMBOL_GPL(net_ipv6_ctl_path);
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static int __net_init ipv6_sysctl_net_init(struct net *net)
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{
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struct ctl_table *ipv6_table;
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struct ctl_table *ipv6_route_table;
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struct ctl_table *ipv6_icmp_table;
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int err;
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err = -ENOMEM;
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ipv6_table = kmemdup(ipv6_table_template, sizeof(ipv6_table_template),
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GFP_KERNEL);
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if (!ipv6_table)
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goto out;
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ipv6_route_table = ipv6_route_sysctl_init(net);
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if (!ipv6_route_table)
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goto out_ipv6_table;
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ipv6_table[0].child = ipv6_route_table;
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ipv6_icmp_table = ipv6_icmp_sysctl_init(net);
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if (!ipv6_icmp_table)
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goto out_ipv6_route_table;
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ipv6_table[1].child = ipv6_icmp_table;
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ipv6_table[2].data = &net->ipv6.sysctl.bindv6only;
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net->ipv6.sysctl.table = register_net_sysctl_table(net, net_ipv6_ctl_path,
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ipv6_table);
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if (!net->ipv6.sysctl.table)
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goto out_ipv6_icmp_table;
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err = 0;
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out:
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return err;
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out_ipv6_icmp_table:
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kfree(ipv6_icmp_table);
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out_ipv6_route_table:
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kfree(ipv6_route_table);
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out_ipv6_table:
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kfree(ipv6_table);
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goto out;
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}
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static void __net_exit ipv6_sysctl_net_exit(struct net *net)
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{
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struct ctl_table *ipv6_table;
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struct ctl_table *ipv6_route_table;
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struct ctl_table *ipv6_icmp_table;
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ipv6_table = net->ipv6.sysctl.table->ctl_table_arg;
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ipv6_route_table = ipv6_table[0].child;
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ipv6_icmp_table = ipv6_table[1].child;
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unregister_net_sysctl_table(net->ipv6.sysctl.table);
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kfree(ipv6_table);
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kfree(ipv6_route_table);
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kfree(ipv6_icmp_table);
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}
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static struct pernet_operations ipv6_sysctl_net_ops = {
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.init = ipv6_sysctl_net_init,
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.exit = ipv6_sysctl_net_exit,
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};
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static struct ctl_table_header *ip6_header;
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int ipv6_sysctl_register(void)
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{
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int err = -ENOMEM;
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ip6_header = register_net_sysctl_rotable(net_ipv6_ctl_path, ipv6_rotable);
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if (ip6_header == NULL)
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goto out;
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err = register_pernet_subsys(&ipv6_sysctl_net_ops);
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if (err)
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goto err_pernet;
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out:
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return err;
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err_pernet:
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unregister_net_sysctl_table(ip6_header);
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goto out;
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}
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void ipv6_sysctl_unregister(void)
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{
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unregister_net_sysctl_table(ip6_header);
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unregister_pernet_subsys(&ipv6_sysctl_net_ops);
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}
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static struct ctl_table_header *ip6_base;
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int ipv6_static_sysctl_register(void)
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{
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ip6_base = register_sysctl_paths(net_ipv6_ctl_path, ipv6_static_skeleton);
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if (ip6_base == NULL)
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return -ENOMEM;
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return 0;
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}
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void ipv6_static_sysctl_unregister(void)
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{
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unregister_net_sysctl_table(ip6_base);
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}
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