[PATCH bpf-next v3 07/12] bpf: add sockmap hooks for UDP sockets

Lorenz Bauer
2020-03-04T10:14:24Z

Add basic psock hooks for UDP sockets. This allows adding and
removing sockets, as well as automatic removal on unhash and close.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
---
MAINTAINERS | 1 +
include/net/udp.h | 5 +++++
net/ipv4/Makefile | 1 +
net/ipv4/udp_bpf.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 60 insertions(+)
create mode 100644 net/ipv4/udp_bpf.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8f27f40d22bb..b2fae56dca9f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9359,6 +9359,7 @@ F: include/linux/skmsg.h
F: net/core/skmsg.c
F: net/core/sock_map.c
F: net/ipv4/tcp_bpf.c
+F: net/ipv4/udp_bpf.c

LANTIQ / INTEL Ethernet drivers
M: Hauke Mehrtens <hauke@hauke-m.de>
diff --git a/include/net/udp.h b/include/net/udp.h
index e55d5f765807..a8fa6c0c6ded 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -503,4 +503,9 @@ static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
return segs;
}

+#ifdef CONFIG_BPF_STREAM_PARSER
+struct sk_psock;
+struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock);
+#endif /* BPF_STREAM_PARSER */
+
#endif /* _UDP_H */
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 9d97bace13c8..9e1a186a3671 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
obj-$(CONFIG_NET_SOCK_MSG) += tcp_bpf.o
+obj-$(CONFIG_BPF_STREAM_PARSER) += udp_bpf.o
obj-$(CONFIG_NETLABEL) += cipso_ipv4.o

obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
new file mode 100644
index 000000000000..eddd973e6575
--- /dev/null
+++ b/net/ipv4/udp_bpf.c
@@ -0,0 +1,53 @@
+// 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>
+
+enum {
+ UDP_BPF_IPV4,
+ UDP_BPF_IPV6,
+ UDP_BPF_NUM_PROTS,
+};
+
+static struct proto *udpv6_prot_saved __read_mostly;
+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->unhash = sock_map_unhash;
+ prot->close = sock_map_close;
+}
+
+static void udp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
+{
+ if (sk->sk_family == AF_INET6 &&
+ 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;
+}
+core_initcall(udp_bpf_v4_build_proto);
+
+struct proto *udp_bpf_get_proto(struct sock *sk, struct sk_psock *psock)
+{
+ int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
+
+ if (!psock->sk_proto)
+ udp_bpf_check_v6_needs_rebuild(sk, READ_ONCE(sk->sk_prot));
+
+ return &udp_bpf_prots[family];
+}
--
2.20.1