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Diffstat (limited to 'net/netlink/af_netlink.c')
-rw-r--r--net/netlink/af_netlink.c72
1 files changed, 65 insertions, 7 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2936fa3b6dc8..da3163d15ef0 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -83,6 +83,11 @@ struct netlink_sock {
struct module *module;
};
+struct listeners_rcu_head {
+ struct rcu_head rcu_head;
+ void *ptr;
+};
+
#define NETLINK_KERNEL_SOCKET 0x1
#define NETLINK_RECV_PKTINFO 0x2
#define NETLINK_BROADCAST_SEND_ERROR 0x4
@@ -1356,7 +1361,7 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
struct netlink_sock *nlk = nlk_sk(sk);
int noblock = flags&MSG_DONTWAIT;
size_t copied;
- struct sk_buff *skb;
+ struct sk_buff *skb, *frag __maybe_unused = NULL;
int err;
if (flags&MSG_OOB)
@@ -1368,6 +1373,35 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
if (skb == NULL)
goto out;
+#ifdef CONFIG_COMPAT_NETLINK_MESSAGES
+ if (unlikely(skb_shinfo(skb)->frag_list)) {
+ bool need_compat = !!(flags & MSG_CMSG_COMPAT);
+
+ /*
+ * If this skb has a frag_list, then here that means that
+ * we will have to use the frag_list skb for compat tasks
+ * and the regular skb for non-compat tasks.
+ *
+ * The skb might (and likely will) be cloned, so we can't
+ * just reset frag_list and go on with things -- we need to
+ * keep that. For the compat case that's easy -- simply get
+ * a reference to the compat skb and free the regular one
+ * including the frag. For the non-compat case, we need to
+ * avoid sending the frag to the user -- so assign NULL but
+ * restore it below before freeing the skb.
+ */
+ if (need_compat) {
+ struct sk_buff *compskb = skb_shinfo(skb)->frag_list;
+ skb_get(compskb);
+ kfree_skb(skb);
+ skb = compskb;
+ } else {
+ frag = skb_shinfo(skb)->frag_list;
+ skb_shinfo(skb)->frag_list = NULL;
+ }
+ }
+#endif
+
msg->msg_namelen = 0;
copied = skb->len;
@@ -1398,6 +1432,11 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
siocb->scm->creds = *NETLINK_CREDS(skb);
if (flags & MSG_TRUNC)
copied = skb->len;
+
+#ifdef CONFIG_COMPAT_NETLINK_MESSAGES
+ skb_shinfo(skb)->frag_list = frag;
+#endif
+
skb_free_datagram(sk, skb);
if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2)
@@ -1453,7 +1492,8 @@ netlink_kernel_create(struct net *net, int unit, unsigned int groups,
if (groups < 32)
groups = 32;
- listeners = kzalloc(NLGRPSZ(groups), GFP_KERNEL);
+ listeners = kzalloc(NLGRPSZ(groups) + sizeof(struct listeners_rcu_head),
+ GFP_KERNEL);
if (!listeners)
goto out_sock_release;
@@ -1501,6 +1541,14 @@ netlink_kernel_release(struct sock *sk)
EXPORT_SYMBOL(netlink_kernel_release);
+static void netlink_free_old_listeners(struct rcu_head *rcu_head)
+{
+ struct listeners_rcu_head *lrh;
+
+ lrh = container_of(rcu_head, struct listeners_rcu_head, rcu_head);
+ kfree(lrh->ptr);
+}
+
/**
* netlink_change_ngroups - change number of multicast groups
*
@@ -1516,6 +1564,7 @@ EXPORT_SYMBOL(netlink_kernel_release);
int netlink_change_ngroups(struct sock *sk, unsigned int groups)
{
unsigned long *listeners, *old = NULL;
+ struct listeners_rcu_head *old_rcu_head;
struct netlink_table *tbl = &nl_table[sk->sk_protocol];
int err = 0;
@@ -1524,7 +1573,9 @@ int netlink_change_ngroups(struct sock *sk, unsigned int groups)
netlink_table_grab();
if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
- listeners = kzalloc(NLGRPSZ(groups), GFP_ATOMIC);
+ listeners = kzalloc(NLGRPSZ(groups) +
+ sizeof(struct listeners_rcu_head),
+ GFP_ATOMIC);
if (!listeners) {
err = -ENOMEM;
goto out_ungrab;
@@ -1532,16 +1583,24 @@ int netlink_change_ngroups(struct sock *sk, unsigned int groups)
old = tbl->listeners;
memcpy(listeners, old, NLGRPSZ(tbl->groups));
rcu_assign_pointer(tbl->listeners, listeners);
+ /*
+ * Free the old memory after an RCU grace period so we
+ * don't leak it. We use call_rcu() here in order to be
+ * able to call this function from atomic contexts. The
+ * allocation of this memory will have reserved enough
+ * space for struct listeners_rcu_head at the end.
+ */
+ old_rcu_head = (void *)(tbl->listeners +
+ NLGRPLONGS(tbl->groups));
+ old_rcu_head->ptr = old;
+ call_rcu(&old_rcu_head->rcu_head, netlink_free_old_listeners);
}
tbl->groups = groups;
out_ungrab:
netlink_table_ungrab();
- synchronize_rcu();
- kfree(old);
return err;
}
-EXPORT_SYMBOL(netlink_change_ngroups);
/**
* netlink_clear_multicast_users - kick off multicast listeners
@@ -1564,7 +1623,6 @@ void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
netlink_table_ungrab();
}
-EXPORT_SYMBOL(netlink_clear_multicast_users);
void netlink_set_nonroot(int protocol, unsigned int flags)
{