diff options
| author | Guillaume Nault <g.nault@alphalink.fr> | 2018-04-12 20:50:33 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-04-13 12:17:26 -0400 |
| commit | 5846c131c39b6d0add36ec19dc8650700690f930 (patch) | |
| tree | d8bbddb871da06b66202ebaf67527dcb3267f19b /net/l2tp/l2tp_core.c | |
| parent | 9267c430c6b6f4c0120e3c6bb847313d633f02a6 (diff) | |
| download | linux-stable-5846c131c39b6d0add36ec19dc8650700690f930.tar.gz | |
l2tp: hold reference on tunnels in netlink dumps
l2tp_tunnel_find_nth() is unsafe: no reference is held on the returned
tunnel, therefore it can be freed whenever the caller uses it.
This patch defines l2tp_tunnel_get_nth() which works similarly, but
also takes a reference on the returned tunnel. The caller then has to
drop it after it stops using the tunnel.
Convert netlink dumps to make them safe against concurrent tunnel
deletion.
Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp/l2tp_core.c')
| -rw-r--r-- | net/l2tp/l2tp_core.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 0fbd3ee26165..c8c4183f0f37 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -183,6 +183,26 @@ struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) } EXPORT_SYMBOL_GPL(l2tp_tunnel_get); +struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) +{ + const struct l2tp_net *pn = l2tp_pernet(net); + struct l2tp_tunnel *tunnel; + int count = 0; + + rcu_read_lock_bh(); + list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { + if (++count > nth) { + l2tp_tunnel_inc_refcount(tunnel); + rcu_read_unlock_bh(); + return tunnel; + } + } + rcu_read_unlock_bh(); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); + /* Lookup a session. A new reference is held on the returned session. */ struct l2tp_session *l2tp_session_get(const struct net *net, struct l2tp_tunnel *tunnel, |