hsr: use rcu_read_lock() in hsr_get_node_{list/status}()

hsr_get_node_{list/status}() are not under rtnl_lock() because
they are callback functions of generic netlink.
But they use __dev_get_by_index() without rtnl_lock().
So, it would use unsafe data.
In order to fix it, rcu_read_lock() and dev_get_by_index_rcu()
are used instead of __dev_get_by_index().

Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 3ba7f61..a64bb64 100644 (file)
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -482,12 +482,9 @@ int hsr_get_node_data(struct hsr_priv *hsr,
        struct hsr_port *port;
        unsigned long tdiff;
 
-       rcu_read_lock();
        node = find_node_by_addr_A(&hsr->node_db, addr);
-       if (!node) {
-               rcu_read_unlock();
-               return -ENOENT; /* No such entry */
-       }
+       if (!node)
+               return -ENOENT;
 
        ether_addr_copy(addr_b, node->macaddress_B);
 
@@ -522,7 +519,5 @@ int hsr_get_node_data(struct hsr_priv *hsr,
                *addr_b_ifindex = -1;
        }
 
-       rcu_read_unlock();
-
        return 0;
 }

diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index 8dc0547..d6760df 100644 (file)
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -251,15 +251,16 @@ static int hsr_get_node_status(struct sk_buff *skb_in, struct genl_info *info)
        if (!na)
                goto invalid;
 
-       hsr_dev = __dev_get_by_index(genl_info_net(info),
-                                    nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+       rcu_read_lock();
+       hsr_dev = dev_get_by_index_rcu(genl_info_net(info),
+                                      nla_get_u32(info->attrs[HSR_A_IFINDEX]));
        if (!hsr_dev)
-               goto invalid;
+               goto rcu_unlock;
        if (!is_hsr_master(hsr_dev))
-               goto invalid;
+               goto rcu_unlock;
 
        /* Send reply */
-       skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+       skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
        if (!skb_out) {
                res = -ENOMEM;
                goto fail;
@@ -313,12 +314,10 @@ static int hsr_get_node_status(struct sk_buff *skb_in, struct genl_info *info)
        res = nla_put_u16(skb_out, HSR_A_IF1_SEQ, hsr_node_if1_seq);
        if (res < 0)
                goto nla_put_failure;
-       rcu_read_lock();
        port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
        if (port)
                res = nla_put_u32(skb_out, HSR_A_IF1_IFINDEX,
                                  port->dev->ifindex);
-       rcu_read_unlock();
        if (res < 0)
                goto nla_put_failure;
 
@@ -328,20 +327,22 @@ static int hsr_get_node_status(struct sk_buff *skb_in, struct genl_info *info)
        res = nla_put_u16(skb_out, HSR_A_IF2_SEQ, hsr_node_if2_seq);
        if (res < 0)
                goto nla_put_failure;
-       rcu_read_lock();
        port = hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
        if (port)
                res = nla_put_u32(skb_out, HSR_A_IF2_IFINDEX,
                                  port->dev->ifindex);
-       rcu_read_unlock();
        if (res < 0)
                goto nla_put_failure;
 
+       rcu_read_unlock();
+
        genlmsg_end(skb_out, msg_head);
        genlmsg_unicast(genl_info_net(info), skb_out, info->snd_portid);
 
        return 0;
 
+rcu_unlock:
+       rcu_read_unlock();
 invalid:
        netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL, NULL);
        return 0;
@@ -351,6 +352,7 @@ nla_put_failure:
        /* Fall through */
 
 fail:
+       rcu_read_unlock();
        return res;
 }
 
@@ -377,15 +379,16 @@ static int hsr_get_node_list(struct sk_buff *skb_in, struct genl_info *info)
        if (!na)
                goto invalid;
 
-       hsr_dev = __dev_get_by_index(genl_info_net(info),
-                                    nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+       rcu_read_lock();
+       hsr_dev = dev_get_by_index_rcu(genl_info_net(info),
+                                      nla_get_u32(info->attrs[HSR_A_IFINDEX]));
        if (!hsr_dev)
-               goto invalid;
+               goto rcu_unlock;
        if (!is_hsr_master(hsr_dev))
-               goto invalid;
+               goto rcu_unlock;
 
        /* Send reply */
-       skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+       skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
        if (!skb_out) {
                res = -ENOMEM;
                goto fail;
@@ -405,14 +408,11 @@ static int hsr_get_node_list(struct sk_buff *skb_in, struct genl_info *info)
 
        hsr = netdev_priv(hsr_dev);
 
-       rcu_read_lock();
        pos = hsr_get_next_node(hsr, NULL, addr);
        while (pos) {
                res = nla_put(skb_out, HSR_A_NODE_ADDR, ETH_ALEN, addr);
-               if (res < 0) {
-                       rcu_read_unlock();
+               if (res < 0)
                        goto nla_put_failure;
-               }
                pos = hsr_get_next_node(hsr, pos, addr);
        }
        rcu_read_unlock();
@@ -422,6 +422,8 @@ static int hsr_get_node_list(struct sk_buff *skb_in, struct genl_info *info)
 
        return 0;
 
+rcu_unlock:
+       rcu_read_unlock();
 invalid:
        netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL, NULL);
        return 0;
@@ -431,6 +433,7 @@ nla_put_failure:
        /* Fall through */
 
 fail:
+       rcu_read_unlock();
        return res;
 }