From f8f2eb9de69a1119117d198547c13d7a1123a5a9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Apr 2024 09:51:04 +0000 Subject: neighbour: add RCU protection to neigh_tables[] In order to remove RTNL protection from neightbl_dump_info() and neigh_dump_info() later, we need to add RCU protection to neigh_tables[]. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/neighbour.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 47d07b122f7a..ccb770539f1a 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -1771,7 +1771,7 @@ static void neigh_parms_destroy(struct neigh_parms *parms) static struct lock_class_key neigh_table_proxy_queue_class; -static struct neigh_table *neigh_tables[NEIGH_NR_TABLES] __read_mostly; +static struct neigh_table __rcu *neigh_tables[NEIGH_NR_TABLES] __read_mostly; void neigh_table_init(int index, struct neigh_table *tbl) { @@ -1828,13 +1828,19 @@ void neigh_table_init(int index, struct neigh_table *tbl) tbl->last_flush = now; tbl->last_rand = now + tbl->parms.reachable_time * 20; - neigh_tables[index] = tbl; + rcu_assign_pointer(neigh_tables[index], tbl); } EXPORT_SYMBOL(neigh_table_init); +/* + * Only called from ndisc_cleanup(), which means this is dead code + * because we no longer can unload IPv6 module. + */ int neigh_table_clear(int index, struct neigh_table *tbl) { - neigh_tables[index] = NULL; + RCU_INIT_POINTER(neigh_tables[index], NULL); + synchronize_rcu(); + /* It is not clean... Fix it to unload IPv6 module safely */ cancel_delayed_work_sync(&tbl->managed_work); cancel_delayed_work_sync(&tbl->gc_work); @@ -1866,10 +1872,10 @@ static struct neigh_table *neigh_find_table(int family) switch (family) { case AF_INET: - tbl = neigh_tables[NEIGH_ARP_TABLE]; + tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ARP_TABLE]); break; case AF_INET6: - tbl = neigh_tables[NEIGH_ND_TABLE]; + tbl = rcu_dereference_rtnl(neigh_tables[NEIGH_ND_TABLE]); break; } @@ -2333,7 +2339,7 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh, ndtmsg = nlmsg_data(nlh); for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) { - tbl = neigh_tables[tidx]; + tbl = rcu_dereference_rtnl(neigh_tables[tidx]); if (!tbl) continue; if (ndtmsg->ndtm_family && tbl->family != ndtmsg->ndtm_family) @@ -2521,7 +2527,7 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) { struct neigh_parms *p; - tbl = neigh_tables[tidx]; + tbl = rcu_dereference_rtnl(neigh_tables[tidx]); if (!tbl) continue; @@ -2881,7 +2887,7 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb) s_t = cb->args[0]; for (t = 0; t < NEIGH_NR_TABLES; t++) { - tbl = neigh_tables[t]; + tbl = rcu_dereference_rtnl(neigh_tables[t]); if (!tbl) continue; @@ -3145,14 +3151,15 @@ int neigh_xmit(int index, struct net_device *dev, const void *addr, struct sk_buff *skb) { int err = -EAFNOSUPPORT; + if (likely(index < NEIGH_NR_TABLES)) { struct neigh_table *tbl; struct neighbour *neigh; - tbl = neigh_tables[index]; - if (!tbl) - goto out; rcu_read_lock(); + tbl = rcu_dereference(neigh_tables[index]); + if (!tbl) + goto out_unlock; if (index == NEIGH_ARP_TABLE) { u32 key = *((u32 *)addr); @@ -3168,6 +3175,7 @@ int neigh_xmit(int index, struct net_device *dev, goto out_kfree_skb; } err = READ_ONCE(neigh->output)(neigh, skb); +out_unlock: rcu_read_unlock(); } else if (index == NEIGH_LINK_TABLE) { -- cgit v1.2.3