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authorGuillaume Nault <g.nault@alphalink.fr>2018-04-12 21:50:35 +0300
committerDavid S. Miller <davem@davemloft.net>2018-04-13 19:17:26 +0300
commitf726214d9b23e5fce8c11937577a289a3202498f (patch)
tree7143db7e1e7c2286a02f5f03a19bb0935e24456f /net/l2tp
parent0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 (diff)
downloadlinux-f726214d9b23e5fce8c11937577a289a3202498f.tar.xz
l2tp: hold reference on tunnels printed in l2tp/tunnels debugfs file
Use l2tp_tunnel_get_nth() instead of l2tp_tunnel_find_nth(), to be safe against concurrent tunnel deletion. Use the same mechanism as in l2tp_ppp.c for dropping the reference taken by l2tp_tunnel_get_nth(). That is, drop the reference just before looking up the next tunnel. In case of error, drop the last accessed tunnel in l2tp_dfs_seq_stop(). That was the last use of l2tp_tunnel_find_nth(). Fixes: 0ad6614048cf ("l2tp: Add debugfs files for dumping l2tp debug info") Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp')
-rw-r--r--net/l2tp/l2tp_core.c20
-rw-r--r--net/l2tp/l2tp_core.h1
-rw-r--r--net/l2tp/l2tp_debugfs.c15
3 files changed, 13 insertions, 23 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index c8c4183f0f37..40261cb68e83 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -355,26 +355,6 @@ err_tlock:
}
EXPORT_SYMBOL_GPL(l2tp_session_register);
-struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)
-{
- 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) {
- rcu_read_unlock_bh();
- return tunnel;
- }
- }
-
- rcu_read_unlock_bh();
-
- return NULL;
-}
-EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
-
/*****************************************************************************
* Receive data handling
*****************************************************************************/
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index e4896413b2b6..c199020f8a8a 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -222,7 +222,6 @@ struct l2tp_session *l2tp_session_get(const struct net *net,
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname);
-struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index 72e713da4733..b8f9d45bfeb1 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -47,7 +47,11 @@ struct l2tp_dfs_seq_data {
static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)
{
- pd->tunnel = l2tp_tunnel_find_nth(pd->net, pd->tunnel_idx);
+ /* Drop reference taken during previous invocation */
+ if (pd->tunnel)
+ l2tp_tunnel_dec_refcount(pd->tunnel);
+
+ pd->tunnel = l2tp_tunnel_get_nth(pd->net, pd->tunnel_idx);
pd->tunnel_idx++;
}
@@ -96,7 +100,14 @@ static void *l2tp_dfs_seq_next(struct seq_file *m, void *v, loff_t *pos)
static void l2tp_dfs_seq_stop(struct seq_file *p, void *v)
{
- /* nothing to do */
+ struct l2tp_dfs_seq_data *pd = v;
+
+ if (!pd || pd == SEQ_START_TOKEN)
+ return;
+
+ /* Drop reference taken by last invocation of l2tp_dfs_next_tunnel() */
+ if (pd->tunnel)
+ l2tp_tunnel_dec_refcount(pd->tunnel);
}
static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)