From 834d97843e3bca86f17cc517885f54f3433427b2 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Thu, 17 Apr 2025 17:03:53 -0700 Subject: [PATCH] ipv6: Protect fib6_link_table() with spinlock. We will get rid of RTNL from RTM_NEWROUTE and SIOCADDRT. If the request specifies a new table ID, fib6_new_table() is called to create a new routing table. Two concurrent requests could specify the same table ID, so we need a lock to protect net->ipv6.fib_table_hash[h]. Let's add a spinlock to protect the hash bucket linkage. Signed-off-by: Kuniyuki Iwashima Acked-by: Paolo Abeni Link: https://patch.msgid.link/20250418000443.43734-13-kuniyu@amazon.com Signed-off-by: Paolo Abeni --- include/net/netns/ipv6.h | 1 + net/ipv6/ip6_fib.c | 26 +++++++++++++++++++++----- 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h index 5f2cfd84570ae..47dc70d8100a4 100644 --- a/include/net/netns/ipv6.h +++ b/include/net/netns/ipv6.h @@ -72,6 +72,7 @@ struct netns_ipv6 { struct rt6_statistics *rt6_stats; struct timer_list ip6_fib_timer; struct hlist_head *fib_table_hash; + spinlock_t fib_table_hash_lock; struct fib6_table *fib6_main_tbl; struct list_head fib6_walkers; rwlock_t fib6_walker_lock; diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index bf727149fdece..79b672f3fc532 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -249,19 +249,33 @@ static struct fib6_table *fib6_alloc_table(struct net *net, u32 id) struct fib6_table *fib6_new_table(struct net *net, u32 id) { - struct fib6_table *tb; + struct fib6_table *tb, *new_tb; if (id == 0) id = RT6_TABLE_MAIN; + tb = fib6_get_table(net, id); if (tb) return tb; - tb = fib6_alloc_table(net, id); - if (tb) - fib6_link_table(net, tb); + new_tb = fib6_alloc_table(net, id); + if (!new_tb) + return NULL; + + spin_lock_bh(&net->ipv6.fib_table_hash_lock); + + tb = fib6_get_table(net, id); + if (unlikely(tb)) { + spin_unlock_bh(&net->ipv6.fib_table_hash_lock); + kfree(new_tb); + return tb; + } - return tb; + fib6_link_table(net, new_tb); + + spin_unlock_bh(&net->ipv6.fib_table_hash_lock); + + return new_tb; } EXPORT_SYMBOL_GPL(fib6_new_table); @@ -2423,6 +2437,8 @@ static int __net_init fib6_net_init(struct net *net) if (!net->ipv6.fib_table_hash) goto out_rt6_stats; + spin_lock_init(&net->ipv6.fib_table_hash_lock); + net->ipv6.fib6_main_tbl = kzalloc(sizeof(*net->ipv6.fib6_main_tbl), GFP_KERNEL); if (!net->ipv6.fib6_main_tbl) -- 2.39.5