From a7e53531234dc206bb75abb5305a72665dd4d75d Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Wed, 4 Mar 2015 15:02:44 -0800 Subject: fib_trie: Make fib_table rcu safe The fib_table was wrapped in several places with an rcu_read_lock/rcu_read_unlock however after looking over the code I found several spots where the tables were being accessed as just standard pointers without any protections. This change fixes that so that all of the proper protections are in place when accessing the table to take RCU replacement or removal of the table into account. Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- include/net/ip_fib.h | 70 +++++++++++++++++++++++++++++------------------- include/net/netns/ipv4.h | 7 ++--- 2 files changed, 46 insertions(+), 31 deletions(-) (limited to 'include') diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index cba4b7c32935..825cb2800908 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -185,6 +185,7 @@ struct fib_table { u32 tb_id; int tb_default; int tb_num_default; + struct rcu_head rcu; unsigned long tb_data[0]; }; @@ -206,12 +207,16 @@ void fib_free_table(struct fib_table *tb); static inline struct fib_table *fib_get_table(struct net *net, u32 id) { + struct hlist_node *tb_hlist; struct hlist_head *ptr; ptr = id == RT_TABLE_LOCAL ? &net->ipv4.fib_table_hash[TABLE_LOCAL_INDEX] : &net->ipv4.fib_table_hash[TABLE_MAIN_INDEX]; - return hlist_entry(ptr->first, struct fib_table, tb_hlist); + + tb_hlist = rcu_dereference_rtnl(hlist_first_rcu(ptr)); + + return hlist_entry(tb_hlist, struct fib_table, tb_hlist); } static inline struct fib_table *fib_new_table(struct net *net, u32 id) @@ -222,15 +227,19 @@ static inline struct fib_table *fib_new_table(struct net *net, u32 id) static inline int fib_lookup(struct net *net, const struct flowi4 *flp, struct fib_result *res) { - int err = -ENETUNREACH; + struct fib_table *tb; + int err; rcu_read_lock(); - if (!fib_table_lookup(fib_get_table(net, RT_TABLE_LOCAL), flp, res, - FIB_LOOKUP_NOREF) || - !fib_table_lookup(fib_get_table(net, RT_TABLE_MAIN), flp, res, - FIB_LOOKUP_NOREF)) - err = 0; + for (err = 0; !err; err = -ENETUNREACH) { + tb = fib_get_table(net, RT_TABLE_LOCAL); + if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF)) + break; + tb = fib_get_table(net, RT_TABLE_MAIN); + if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF)) + break; + } rcu_read_unlock(); @@ -249,28 +258,33 @@ int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res); static inline int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res) { - if (!net->ipv4.fib_has_custom_rules) { - int err = -ENETUNREACH; - - rcu_read_lock(); - - res->tclassid = 0; - if ((net->ipv4.fib_local && - !fib_table_lookup(net->ipv4.fib_local, flp, res, - FIB_LOOKUP_NOREF)) || - (net->ipv4.fib_main && - !fib_table_lookup(net->ipv4.fib_main, flp, res, - FIB_LOOKUP_NOREF)) || - (net->ipv4.fib_default && - !fib_table_lookup(net->ipv4.fib_default, flp, res, - FIB_LOOKUP_NOREF))) - err = 0; - - rcu_read_unlock(); - - return err; + struct fib_table *tb; + int err; + + if (net->ipv4.fib_has_custom_rules) + return __fib_lookup(net, flp, res); + + rcu_read_lock(); + + res->tclassid = 0; + + for (err = 0; !err; err = -ENETUNREACH) { + tb = rcu_dereference_rtnl(net->ipv4.fib_local); + if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF)) + break; + + tb = rcu_dereference_rtnl(net->ipv4.fib_main); + if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF)) + break; + + tb = rcu_dereference_rtnl(net->ipv4.fib_default); + if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF)) + break; } - return __fib_lookup(net, flp, res); + + rcu_read_unlock(); + + return err; } #endif /* CONFIG_IP_MULTIPLE_TABLES */ diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 1b26c6c3fd7c..db1db158a00e 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -7,6 +7,7 @@ #include #include +#include struct tcpm_hash_bucket; struct ctl_table_header; @@ -38,9 +39,9 @@ struct netns_ipv4 { #ifdef CONFIG_IP_MULTIPLE_TABLES struct fib_rules_ops *rules_ops; bool fib_has_custom_rules; - struct fib_table *fib_local; - struct fib_table *fib_main; - struct fib_table *fib_default; + struct fib_table __rcu *fib_local; + struct fib_table __rcu *fib_main; + struct fib_table __rcu *fib_default; #endif #ifdef CONFIG_IP_ROUTE_CLASSID int fib_num_tclassid_users; -- cgit v1.2.3