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Diffstat (limited to 'net/ipv4/udp_bpf.c')
-rw-r--r--net/ipv4/udp_bpf.c157
1 files changed, 157 insertions, 0 deletions
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
new file mode 100644
index 000000000..0735d820e
--- /dev/null
+++ b/net/ipv4/udp_bpf.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Cloudflare Ltd https://cloudflare.com */
+
+#include <linux/skmsg.h>
+#include <net/sock.h>
+#include <net/udp.h>
+#include <net/inet_common.h>
+
+#include "udp_impl.h"
+
+static struct proto *udpv6_prot_saved __read_mostly;
+
+static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
+ int flags, int *addr_len)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == AF_INET6)
+ return udpv6_prot_saved->recvmsg(sk, msg, len, flags, addr_len);
+#endif
+ return udp_prot.recvmsg(sk, msg, len, flags, addr_len);
+}
+
+static bool udp_sk_has_data(struct sock *sk)
+{
+ return !skb_queue_empty(&udp_sk(sk)->reader_queue) ||
+ !skb_queue_empty(&sk->sk_receive_queue);
+}
+
+static bool psock_has_data(struct sk_psock *psock)
+{
+ return !skb_queue_empty(&psock->ingress_skb) ||
+ !sk_psock_queue_empty(psock);
+}
+
+#define udp_msg_has_data(__sk, __psock) \
+ ({ udp_sk_has_data(__sk) || psock_has_data(__psock); })
+
+static int udp_msg_wait_data(struct sock *sk, struct sk_psock *psock,
+ long timeo)
+{
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+ int ret = 0;
+
+ if (sk->sk_shutdown & RCV_SHUTDOWN)
+ return 1;
+
+ if (!timeo)
+ return ret;
+
+ add_wait_queue(sk_sleep(sk), &wait);
+ sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ ret = udp_msg_has_data(sk, psock);
+ if (!ret) {
+ wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+ ret = udp_msg_has_data(sk, psock);
+ }
+ sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ remove_wait_queue(sk_sleep(sk), &wait);
+ return ret;
+}
+
+static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
+ int flags, int *addr_len)
+{
+ struct sk_psock *psock;
+ int copied, ret;
+
+ if (unlikely(flags & MSG_ERRQUEUE))
+ return inet_recv_error(sk, msg, len, addr_len);
+
+ if (!len)
+ return 0;
+
+ psock = sk_psock_get(sk);
+ if (unlikely(!psock))
+ return sk_udp_recvmsg(sk, msg, len, flags, addr_len);
+
+ if (!psock_has_data(psock)) {
+ ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
+ goto out;
+ }
+
+msg_bytes_ready:
+ copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+ if (!copied) {
+ long timeo;
+ int data;
+
+ timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+ data = udp_msg_wait_data(sk, psock, timeo);
+ if (data) {
+ if (psock_has_data(psock))
+ goto msg_bytes_ready;
+ ret = sk_udp_recvmsg(sk, msg, len, flags, addr_len);
+ goto out;
+ }
+ copied = -EAGAIN;
+ }
+ ret = copied;
+out:
+ sk_psock_put(sk, psock);
+ return ret;
+}
+
+enum {
+ UDP_BPF_IPV4,
+ UDP_BPF_IPV6,
+ UDP_BPF_NUM_PROTS,
+};
+
+static DEFINE_SPINLOCK(udpv6_prot_lock);
+static struct proto udp_bpf_prots[UDP_BPF_NUM_PROTS];
+
+static void udp_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+{
+ *prot = *base;
+ prot->close = sock_map_close;
+ prot->recvmsg = udp_bpf_recvmsg;
+ prot->sock_is_readable = sk_msg_is_readable;
+}
+
+static void udp_bpf_check_v6_needs_rebuild(struct proto *ops)
+{
+ if (unlikely(ops != smp_load_acquire(&udpv6_prot_saved))) {
+ spin_lock_bh(&udpv6_prot_lock);
+ if (likely(ops != udpv6_prot_saved)) {
+ udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV6], ops);
+ smp_store_release(&udpv6_prot_saved, ops);
+ }
+ spin_unlock_bh(&udpv6_prot_lock);
+ }
+}
+
+static int __init udp_bpf_v4_build_proto(void)
+{
+ udp_bpf_rebuild_protos(&udp_bpf_prots[UDP_BPF_IPV4], &udp_prot);
+ return 0;
+}
+late_initcall(udp_bpf_v4_build_proto);
+
+int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+ int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
+
+ if (restore) {
+ sk->sk_write_space = psock->saved_write_space;
+ sock_replace_proto(sk, psock->sk_proto);
+ return 0;
+ }
+
+ if (sk->sk_family == AF_INET6)
+ udp_bpf_check_v6_needs_rebuild(psock->sk_proto);
+
+ sock_replace_proto(sk, &udp_bpf_prots[family]);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(udp_bpf_update_proto);