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Diffstat (limited to 'net/ipv4/udp.c')
-rw-r--r--net/ipv4/udp.c116
1 files changed, 86 insertions, 30 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 6a01905d379f..c472c9a57cf6 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -420,6 +420,49 @@ u32 udp_ehashfn(const struct net *net, const __be32 laddr, const __u16 lport,
}
EXPORT_SYMBOL(udp_ehashfn);
+/**
+ * udp4_lib_lookup1() - Simplified lookup using primary hash (destination port)
+ * @net: Network namespace
+ * @saddr: Source address, network order
+ * @sport: Source port, network order
+ * @daddr: Destination address, network order
+ * @hnum: Destination port, host order
+ * @dif: Destination interface index
+ * @sdif: Destination bridge port index, if relevant
+ * @udptable: Set of UDP hash tables
+ *
+ * Simplified lookup to be used as fallback if no sockets are found due to a
+ * potential race between (receive) address change, and lookup happening before
+ * the rehash operation. This function ignores SO_REUSEPORT groups while scoring
+ * result sockets, because if we have one, we don't need the fallback at all.
+ *
+ * Called under rcu_read_lock().
+ *
+ * Return: socket with highest matching score if any, NULL if none
+ */
+static struct sock *udp4_lib_lookup1(const struct net *net,
+ __be32 saddr, __be16 sport,
+ __be32 daddr, unsigned int hnum,
+ int dif, int sdif,
+ const struct udp_table *udptable)
+{
+ unsigned int slot = udp_hashfn(net, hnum, udptable->mask);
+ struct udp_hslot *hslot = &udptable->hash[slot];
+ struct sock *sk, *result = NULL;
+ int score, badness = 0;
+
+ sk_for_each_rcu(sk, &hslot->head) {
+ score = compute_score(sk, net,
+ saddr, sport, daddr, hnum, dif, sdif);
+ if (score > badness) {
+ result = sk;
+ badness = score;
+ }
+ }
+
+ return result;
+}
+
/* called with rcu_read_lock() */
static struct sock *udp4_lib_lookup2(const struct net *net,
__be32 saddr, __be16 sport,
@@ -533,7 +576,7 @@ begin:
return NULL;
}
-/* In hash4, rehash can happen in connect(), where hash4_cnt keeps unchanged. */
+/* udp_rehash4() only checks hslot4, and hash4_cnt is not processed. */
static void udp_rehash4(struct udp_table *udptable, struct sock *sk,
u16 newhash4)
{
@@ -582,15 +625,13 @@ void udp_lib_hash4(struct sock *sk, u16 hash)
struct net *net = sock_net(sk);
struct udp_table *udptable;
- /* Connected udp socket can re-connect to another remote address,
- * so rehash4 is needed.
+ /* Connected udp socket can re-connect to another remote address, which
+ * will be handled by rehash. Thus no need to redo hash4 here.
*/
- udptable = net->ipv4.udp_table;
- if (udp_hashed4(sk)) {
- udp_rehash4(udptable, sk, hash);
+ if (udp_hashed4(sk))
return;
- }
+ udptable = net->ipv4.udp_table;
hslot = udp_hashslot(udptable, net, udp_sk(sk)->udp_port_hash);
hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
hslot4 = udp_hashslot4(udptable, hash);
@@ -683,6 +724,19 @@ struct sock *__udp4_lib_lookup(const struct net *net, __be32 saddr,
result = udp4_lib_lookup2(net, saddr, sport,
htonl(INADDR_ANY), hnum, dif, sdif,
hslot2, skb);
+ if (!IS_ERR_OR_NULL(result))
+ goto done;
+
+ /* Primary hash (destination port) lookup as fallback for this race:
+ * 1. __ip4_datagram_connect() sets sk_rcv_saddr
+ * 2. lookup (this function): new sk_rcv_saddr, hashes not updated yet
+ * 3. rehash operation updating _secondary and four-tuple_ hashes
+ * The primary hash doesn't need an update after 1., so, thanks to this
+ * further step, 1. and 3. don't need to be atomic against the lookup.
+ */
+ result = udp4_lib_lookup1(net, saddr, sport, daddr, hnum, dif, sdif,
+ udptable);
+
done:
if (IS_ERR(result))
return NULL;
@@ -1674,7 +1728,6 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
struct sk_buff_head *list = &sk->sk_receive_queue;
int rmem, err = -ENOMEM;
spinlock_t *busy = NULL;
- bool becomes_readable;
int size, rcvbuf;
/* Immediately drop when the receive queue is full.
@@ -1715,19 +1768,12 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
*/
sock_skb_set_dropcount(sk, skb);
- becomes_readable = skb_queue_empty(list);
__skb_queue_tail(list, skb);
spin_unlock(&list->lock);
- if (!sock_flag(sk, SOCK_DEAD)) {
- if (becomes_readable ||
- sk->sk_data_ready != sock_def_readable ||
- READ_ONCE(sk->sk_peek_off) >= 0)
- INDIRECT_CALL_1(sk->sk_data_ready,
- sock_def_readable, sk);
- else
- sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_IN);
- }
+ if (!sock_flag(sk, SOCK_DEAD))
+ INDIRECT_CALL_1(sk->sk_data_ready, sock_def_readable, sk);
+
busylock_release(busy);
return 0;
@@ -2181,14 +2227,14 @@ void udp_lib_rehash(struct sock *sk, u16 newhash, u16 newhash4)
struct udp_table *udptable = udp_get_table_prot(sk);
struct udp_hslot *hslot, *hslot2, *nhslot2;
+ hslot = udp_hashslot(udptable, sock_net(sk),
+ udp_sk(sk)->udp_port_hash);
hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
nhslot2 = udp_hashslot2(udptable, newhash);
udp_sk(sk)->udp_portaddr_hash = newhash;
if (hslot2 != nhslot2 ||
rcu_access_pointer(sk->sk_reuseport_cb)) {
- hslot = udp_hashslot(udptable, sock_net(sk),
- udp_sk(sk)->udp_port_hash);
/* we must lock primary chain too */
spin_lock_bh(&hslot->lock);
if (rcu_access_pointer(sk->sk_reuseport_cb))
@@ -2207,19 +2253,29 @@ void udp_lib_rehash(struct sock *sk, u16 newhash, u16 newhash4)
spin_unlock(&nhslot2->lock);
}
- if (udp_hashed4(sk)) {
- udp_rehash4(udptable, sk, newhash4);
+ spin_unlock_bh(&hslot->lock);
+ }
- if (hslot2 != nhslot2) {
- spin_lock(&hslot2->lock);
- udp_hash4_dec(hslot2);
- spin_unlock(&hslot2->lock);
+ /* Now process hash4 if necessary:
+ * (1) update hslot4;
+ * (2) update hslot2->hash4_cnt.
+ * Note that hslot2/hslot4 should be checked separately, as
+ * either of them may change with the other unchanged.
+ */
+ if (udp_hashed4(sk)) {
+ spin_lock_bh(&hslot->lock);
- spin_lock(&nhslot2->lock);
- udp_hash4_inc(nhslot2);
- spin_unlock(&nhslot2->lock);
- }
+ udp_rehash4(udptable, sk, newhash4);
+ if (hslot2 != nhslot2) {
+ spin_lock(&hslot2->lock);
+ udp_hash4_dec(hslot2);
+ spin_unlock(&hslot2->lock);
+
+ spin_lock(&nhslot2->lock);
+ udp_hash4_inc(nhslot2);
+ spin_unlock(&nhslot2->lock);
}
+
spin_unlock_bh(&hslot->lock);
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-07 20:31:56 +0000