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authorGuillaume Nault <g.nault@alphalink.fr>2017-03-31 13:02:30 +0200
committerDavid S. Miller <davem@davemloft.net>2017-04-01 20:16:41 -0700
commit2777e2ab5a9cf2b4524486c6db1517a6ded25261 (patch)
tree7143c7c597ae638f5b9587c576824e8aec91523d /net/l2tp/l2tp_netlink.c
parent5e6a9e5a3554a5b3db09cdc22253af1849c65dff (diff)
l2tp: take a reference on sessions used in genetlink handlers
Callers of l2tp_nl_session_find() need to hold a reference on the returned session since there's no guarantee that it isn't going to disappear from under them. Relying on the fact that no l2tp netlink message may be processed concurrently isn't enough: sessions can be deleted by other means (e.g. by closing the PPPOL2TP socket of a ppp pseudowire). l2tp_nl_cmd_session_delete() is a bit special: it runs a callback function that may require a previous call to session->ref(). In particular, for ppp pseudowires, the callback is l2tp_session_delete(), which then calls pppol2tp_session_close() and dereferences the PPPOL2TP socket. The socket might already be gone at the moment l2tp_session_delete() calls session->ref(), so we need to take a reference during the session lookup. So we need to pass the do_ref variable down to l2tp_session_get() and l2tp_session_get_by_ifname(). Since all callers have to be updated, l2tp_session_find_by_ifname() and l2tp_nl_session_find() are renamed to reflect their new behaviour. 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_netlink.c')
-rw-r--r--net/l2tp/l2tp_netlink.c39
1 files changed, 26 insertions, 13 deletions
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index f1b68effb077..93e317377c66 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -48,7 +48,8 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 portid, u32 seq,
/* Accessed under genl lock */
static const struct l2tp_nl_cmd_ops *l2tp_nl_cmd_ops[__L2TP_PWTYPE_MAX];
-static struct l2tp_session *l2tp_nl_session_find(struct genl_info *info)
+static struct l2tp_session *l2tp_nl_session_get(struct genl_info *info,
+ bool do_ref)
{
u32 tunnel_id;
u32 session_id;
@@ -59,14 +60,15 @@ static struct l2tp_session *l2tp_nl_session_find(struct genl_info *info)
if (info->attrs[L2TP_ATTR_IFNAME]) {
ifname = nla_data(info->attrs[L2TP_ATTR_IFNAME]);
- session = l2tp_session_find_by_ifname(net, ifname);
+ session = l2tp_session_get_by_ifname(net, ifname, do_ref);
} else if ((info->attrs[L2TP_ATTR_SESSION_ID]) &&
(info->attrs[L2TP_ATTR_CONN_ID])) {
tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);
tunnel = l2tp_tunnel_find(net, tunnel_id);
if (tunnel)
- session = l2tp_session_find(net, tunnel, session_id);
+ session = l2tp_session_get(net, tunnel, session_id,
+ do_ref);
}
return session;
@@ -660,7 +662,7 @@ static int l2tp_nl_cmd_session_delete(struct sk_buff *skb, struct genl_info *inf
struct l2tp_session *session;
u16 pw_type;
- session = l2tp_nl_session_find(info);
+ session = l2tp_nl_session_get(info, true);
if (session == NULL) {
ret = -ENODEV;
goto out;
@@ -674,6 +676,10 @@ static int l2tp_nl_cmd_session_delete(struct sk_buff *skb, struct genl_info *inf
if (l2tp_nl_cmd_ops[pw_type] && l2tp_nl_cmd_ops[pw_type]->session_delete)
ret = (*l2tp_nl_cmd_ops[pw_type]->session_delete)(session);
+ if (session->deref)
+ session->deref(session);
+ l2tp_session_dec_refcount(session);
+
out:
return ret;
}
@@ -683,7 +689,7 @@ static int l2tp_nl_cmd_session_modify(struct sk_buff *skb, struct genl_info *inf
int ret = 0;
struct l2tp_session *session;
- session = l2tp_nl_session_find(info);
+ session = l2tp_nl_session_get(info, false);
if (session == NULL) {
ret = -ENODEV;
goto out;
@@ -718,6 +724,8 @@ static int l2tp_nl_cmd_session_modify(struct sk_buff *skb, struct genl_info *inf
ret = l2tp_session_notify(&l2tp_nl_family, info,
session, L2TP_CMD_SESSION_MODIFY);
+ l2tp_session_dec_refcount(session);
+
out:
return ret;
}
@@ -813,29 +821,34 @@ static int l2tp_nl_cmd_session_get(struct sk_buff *skb, struct genl_info *info)
struct sk_buff *msg;
int ret;
- session = l2tp_nl_session_find(info);
+ session = l2tp_nl_session_get(info, false);
if (session == NULL) {
ret = -ENODEV;
- goto out;
+ goto err;
}
msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (!msg) {
ret = -ENOMEM;
- goto out;
+ goto err_ref;
}
ret = l2tp_nl_session_send(msg, info->snd_portid, info->snd_seq,
0, session, L2TP_CMD_SESSION_GET);
if (ret < 0)
- goto err_out;
+ goto err_ref_msg;
- return genlmsg_unicast(genl_info_net(info), msg, info->snd_portid);
+ ret = genlmsg_unicast(genl_info_net(info), msg, info->snd_portid);
-err_out:
- nlmsg_free(msg);
+ l2tp_session_dec_refcount(session);
-out:
+ return ret;
+
+err_ref_msg:
+ nlmsg_free(msg);
+err_ref:
+ l2tp_session_dec_refcount(session);
+err:
return ret;
}