diff options
| author | Guillaume Nault <gnault@redhat.com> | 2020-01-13 22:39:22 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-01-14 11:28:40 -0800 |
| commit | 2dce224f469f060b9998a5a869151ef83c08ce77 (patch) | |
| tree | 2d192faaecde1c8af7bd6e8be08d69951735be35 /net/core | |
| parent | 4905294162bda43bef65b411cf791005c7e15b28 (diff) | |
netns: protect netns ID lookups with RCU
__peernet2id() can be protected by RCU as it only calls idr_for_each(),
which is RCU-safe, and never modifies the nsid table.
rtnl_net_dumpid() can also do lockless lookups. It does two nested
idr_for_each() calls on nsid tables (one direct call and one indirect
call because of rtnl_net_dumpid_one() calling __peernet2id()). The
netnsid tables are never updated. Therefore it is safe to not take the
nsid_lock and run within an RCU-critical section instead.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/net_namespace.c | 22 |
1 files changed, 7 insertions, 15 deletions
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 05e07d24b45b..e7a5ff4966c9 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -211,7 +211,7 @@ static int net_eq_idr(int id, void *net, void *peer) return 0; } -/* Should be called with nsid_lock held. */ +/* Must be called from RCU-critical section or with nsid_lock held */ static int __peernet2id(const struct net *net, struct net *peer) { int id = idr_for_each(&net->netns_ids, net_eq_idr, peer); @@ -272,9 +272,10 @@ int peernet2id(struct net *net, struct net *peer) { int id; - spin_lock_bh(&net->nsid_lock); + rcu_read_lock(); id = __peernet2id(net, peer); - spin_unlock_bh(&net->nsid_lock); + rcu_read_unlock(); + return id; } EXPORT_SYMBOL(peernet2id); @@ -941,6 +942,7 @@ struct rtnl_net_dump_cb { int s_idx; }; +/* Runs in RCU-critical section. */ static int rtnl_net_dumpid_one(int id, void *peer, void *data) { struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data; @@ -1025,19 +1027,9 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb) goto end; } - spin_lock_bh(&net_cb.tgt_net->nsid_lock); - if (net_cb.fillargs.add_ref && - !net_eq(net_cb.ref_net, net_cb.tgt_net) && - !spin_trylock_bh(&net_cb.ref_net->nsid_lock)) { - spin_unlock_bh(&net_cb.tgt_net->nsid_lock); - err = -EAGAIN; - goto end; - } + rcu_read_lock(); idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb); - if (net_cb.fillargs.add_ref && - !net_eq(net_cb.ref_net, net_cb.tgt_net)) - spin_unlock_bh(&net_cb.ref_net->nsid_lock); - spin_unlock_bh(&net_cb.tgt_net->nsid_lock); + rcu_read_unlock(); cb->args[0] = net_cb.idx; end: |