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authorGuillaume Nault <g.nault@alphalink.fr>2017-08-25 16:51:40 +0200
committerDavid S. Miller <davem@davemloft.net>2017-08-28 11:34:58 -0700
commit54652eb12c1b72e9602d09cb2821d5760939190f (patch)
tree3f53546dd44567d09e5070f0dbc8917902f6882e /net/l2tp/l2tp_core.h
parent9ee369a405c57613d7c83a3967780c3e30c52ecc (diff)
downloadlinux-54652eb12c1b72e9602d09cb2821d5760939190f.tar.bz2
l2tp: hold tunnel while looking up sessions in l2tp_netlink
l2tp_tunnel_find() doesn't take a reference on the returned tunnel. Therefore, it's unsafe to use it because the returned tunnel can go away on us anytime. Fix this by defining l2tp_tunnel_get(), which works like l2tp_tunnel_find(), but takes a reference on the returned tunnel. Caller then has to drop this reference using l2tp_tunnel_dec_refcount(). As l2tp_tunnel_dec_refcount() needs to be moved to l2tp_core.h, let's simplify the patch and not move the L2TP_REFCNT_DEBUG part. This code has been broken (not even compiling) in May 2012 by commit a4ca44fa578c ("net: l2tp: Standardize logging styles") and fixed more than two years later by commit 29abe2fda54f ("l2tp: fix missing line continuation"). So it doesn't appear to be used by anyone. Same thing for l2tp_tunnel_free(); instead of moving it to l2tp_core.h, let's just simplify things and call kfree_rcu() directly in l2tp_tunnel_dec_refcount(). Extra assertions and debugging code provided by l2tp_tunnel_free() didn't help catching any of the reference counting and socket handling issues found while working on this series. 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.h')
-rw-r--r--net/l2tp/l2tp_core.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index cdb6e3327f74..9101297f27ad 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -231,6 +231,8 @@ out:
return tunnel;
}
+struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
+
struct l2tp_session *l2tp_session_get(const struct net *net,
struct l2tp_tunnel *tunnel,
u32 session_id, bool do_ref);
@@ -269,6 +271,17 @@ int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
+static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
+{
+ refcount_inc(&tunnel->ref_count);
+}
+
+static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
+{
+ if (refcount_dec_and_test(&tunnel->ref_count))
+ kfree_rcu(tunnel, rcu);
+}
+
/* Session reference counts. Incremented when code obtains a reference
* to a session.
*/