l2tp: take reference on sessions being dumped
[ Upstream commit e08293a4ccbcc993ded0fdc46f1e57926b833d63 ]
Take a reference on the sessions returned by l2tp_session_find_nth()
(and rename it l2tp_session_get_nth() to reflect this change), so that
caller is assured that the session isn't going to disappear while
processing it.
For procfs and debugfs handlers, the session is held in the .start()
callback and dropped in .show(). Given that pppol2tp_seq_session_show()
dereferences the associated PPPoL2TP socket and that
l2tp_dfs_seq_session_show() might call pppol2tp_show(), we also need to
call the session's .ref() callback to prevent the socket from going
away from under us.
Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Fixes: 0ad6614048cf ("l2tp: Add debugfs files for dumping l2tp debug info")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index a2ed3bd..e702cb95 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -278,7 +278,8 @@
}
EXPORT_SYMBOL_GPL(l2tp_session_find);
-struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
+struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
+ bool do_ref)
{
int hash;
struct l2tp_session *session;
@@ -288,6 +289,9 @@
for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
if (++count > nth) {
+ l2tp_session_inc_refcount(session);
+ if (do_ref && session->ref)
+ session->ref(session);
read_unlock_bh(&tunnel->hlist_lock);
return session;
}
@@ -298,7 +302,7 @@
return NULL;
}
-EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
+EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
/* Lookup a session by interface name.
* This is very inefficient but is only used by management interfaces.
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 181e755c..e7233ba 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -243,7 +243,8 @@
struct l2tp_session *l2tp_session_find(struct net *net,
struct l2tp_tunnel *tunnel,
u32 session_id);
-struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth);
+struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
+ bool do_ref);
struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname);
struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);
diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index 2d6760a..d100aed 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -53,7 +53,7 @@
static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
{
- pd->session = l2tp_session_find_nth(pd->tunnel, pd->session_idx);
+ pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx, true);
pd->session_idx++;
if (pd->session == NULL) {
@@ -238,10 +238,14 @@
}
/* Show the tunnel or session context */
- if (pd->session == NULL)
+ if (!pd->session) {
l2tp_dfs_seq_tunnel_show(m, pd->tunnel);
- else
+ } else {
l2tp_dfs_seq_session_show(m, pd->session);
+ if (pd->session->deref)
+ pd->session->deref(pd->session);
+ l2tp_session_dec_refcount(pd->session);
+ }
out:
return 0;
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index bf31177..9f66272 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -844,7 +844,7 @@
goto out;
}
- session = l2tp_session_find_nth(tunnel, si);
+ session = l2tp_session_get_nth(tunnel, si, false);
if (session == NULL) {
ti++;
tunnel = NULL;
@@ -854,8 +854,11 @@
if (l2tp_nl_session_send(skb, NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq, NLM_F_MULTI,
- session, L2TP_CMD_SESSION_GET) < 0)
+ session, L2TP_CMD_SESSION_GET) < 0) {
+ l2tp_session_dec_refcount(session);
break;
+ }
+ l2tp_session_dec_refcount(session);
si++;
}
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 51c190d..4db3317 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1555,7 +1555,7 @@
static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
{
- pd->session = l2tp_session_find_nth(pd->tunnel, pd->session_idx);
+ pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx, true);
pd->session_idx++;
if (pd->session == NULL) {
@@ -1682,10 +1682,14 @@
/* Show the tunnel or session context.
*/
- if (pd->session == NULL)
+ if (!pd->session) {
pppol2tp_seq_tunnel_show(m, pd->tunnel);
- else
+ } else {
pppol2tp_seq_session_show(m, pd->session);
+ if (pd->session->deref)
+ pd->session->deref(pd->session);
+ l2tp_session_dec_refcount(pd->session);
+ }
out:
return 0;