net: xfrm: Add '_rcu' tag for rcu protected pointer in netns_xfrm

For rcu protected pointers, we'd better add '__rcu' for them.

Once added '__rcu' tag for rcu protected pointer, the sparse tool reports
warnings.

net/xfrm/xfrm_user.c:1198:39: sparse:    expected struct sock *sk
net/xfrm/xfrm_user.c:1198:39: sparse:    got struct sock [noderef] <asn:4> *nlsk
[...]

So introduce a new wrapper function of nlmsg_unicast  to handle type
conversions.

This patch also fixes a direct access of a rcu protected socket.

Fixes: be33690d8fcf("[XFRM]: Fix aevent related crash")
Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 59f45b1..d2a36fb 100644 (file)
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -57,7 +57,7 @@ struct netns_xfrm {
        struct list_head        inexact_bins;
 
 
-       struct sock             *nlsk;
+       struct sock             __rcu *nlsk;
        struct sock             *nlsk_stash;
 
        u32                     sysctl_aevent_etime;

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 8d4d52f..9445898 100644 (file)
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1071,6 +1071,22 @@ static inline int xfrm_nlmsg_multicast(struct net *net, struct sk_buff *skb,
        return nlmsg_multicast(nlsk, skb, pid, group, GFP_ATOMIC);
 }
 
+/* A similar wrapper like xfrm_nlmsg_multicast checking that nlsk is still
+ * available.
+ */
+static inline int xfrm_nlmsg_unicast(struct net *net, struct sk_buff *skb,
+                                    u32 pid)
+{
+       struct sock *nlsk = rcu_dereference(net->xfrm.nlsk);
+
+       if (!nlsk) {
+               kfree_skb(skb);
+               return -EPIPE;
+       }
+
+       return nlmsg_unicast(nlsk, skb, pid);
+}
+
 static inline unsigned int xfrm_spdinfo_msgsize(void)
 {
        return NLMSG_ALIGN(4)
@@ -1195,7 +1211,7 @@ static int xfrm_get_spdinfo(struct sk_buff *skb, struct nlmsghdr *nlh,
        err = build_spdinfo(r_skb, net, sportid, seq, *flags);
        BUG_ON(err < 0);
 
-       return nlmsg_unicast(net->xfrm.nlsk, r_skb, sportid);
+       return xfrm_nlmsg_unicast(net, r_skb, sportid);
 }
 
 static inline unsigned int xfrm_sadinfo_msgsize(void)
@@ -1254,7 +1270,7 @@ static int xfrm_get_sadinfo(struct sk_buff *skb, struct nlmsghdr *nlh,
        err = build_sadinfo(r_skb, net, sportid, seq, *flags);
        BUG_ON(err < 0);
 
-       return nlmsg_unicast(net->xfrm.nlsk, r_skb, sportid);
+       return xfrm_nlmsg_unicast(net, r_skb, sportid);
 }
 
 static int xfrm_get_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -1274,7 +1290,7 @@ static int xfrm_get_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
        if (IS_ERR(resp_skb)) {
                err = PTR_ERR(resp_skb);
        } else {
-               err = nlmsg_unicast(net->xfrm.nlsk, resp_skb, NETLINK_CB(skb).portid);
+               err = xfrm_nlmsg_unicast(net, resp_skb, NETLINK_CB(skb).portid);
        }
        xfrm_state_put(x);
 out_noput:
@@ -1337,7 +1353,7 @@ static int xfrm_alloc_userspi(struct sk_buff *skb, struct nlmsghdr *nlh,
                goto out;
        }
 
-       err = nlmsg_unicast(net->xfrm.nlsk, resp_skb, NETLINK_CB(skb).portid);
+       err = xfrm_nlmsg_unicast(net, resp_skb, NETLINK_CB(skb).portid);
 
 out:
        xfrm_state_put(x);
@@ -1903,8 +1919,8 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
                if (IS_ERR(resp_skb)) {
                        err = PTR_ERR(resp_skb);
                } else {
-                       err = nlmsg_unicast(net->xfrm.nlsk, resp_skb,
-                                           NETLINK_CB(skb).portid);
+                       err = xfrm_nlmsg_unicast(net, resp_skb,
+                                                NETLINK_CB(skb).portid);
                }
        } else {
                xfrm_audit_policy_delete(xp, err ? 0 : 1, true);
@@ -2062,7 +2078,7 @@ static int xfrm_get_ae(struct sk_buff *skb, struct nlmsghdr *nlh,
        err = build_aevent(r_skb, x, &c);
        BUG_ON(err < 0);
 
-       err = nlmsg_unicast(net->xfrm.nlsk, r_skb, NETLINK_CB(skb).portid);
+       err = xfrm_nlmsg_unicast(net, r_skb, NETLINK_CB(skb).portid);
        spin_unlock_bh(&x->lock);
        xfrm_state_put(x);
        return err;