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| author | Guillaume Nault <g.nault@alphalink.fr> | 2017-08-25 17:51:40 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-28 21:34:58 +0300 |
| commit | 54652eb12c1b72e9602d09cb2821d5760939190f (patch) | |
| tree | 3f53546dd44567d09e5070f0dbc8917902f6882e /net/l2tp/l2tp_core.h | |
| parent | 9ee369a405c57613d7c83a3967780c3e30c52ecc (diff) | |
| download | linux-54652eb12c1b72e9602d09cb2821d5760939190f.tar.xz | |
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.h | 13 |
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. */ |