selftests/bpf: Implement sample udp/udp6 bpf_iter programs

On my VM, I got identical results between /proc/net/udp[6] and
the udp{4,6} bpf iterator.

For udp6:
  $ cat /sys/fs/bpf/p1
    sl  local_address                         remote_address                        st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops
   1405: 000080FE00000000FF7CC4D0D9EFE4FE:0222 00000000000000000000000000000000:0000 07 00000000:00000000 00:00000000 00000000   193        0 19183 2 0000000029eab111 0
  $ cat /proc/net/udp6
    sl  local_address                         remote_address                        st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops
   1405: 000080FE00000000FF7CC4D0D9EFE4FE:0222 00000000000000000000000000000000:0000 07 00000000:00000000 00:00000000 00000000   193        0 19183 2 0000000029eab111 0

For udp4:
  $ cat /sys/fs/bpf/p4
    sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops
   2007: 00000000:1F90 00000000:0000 07 00000000:00000000 00:00000000 00000000     0        0 72540 2 000000004ede477a 0
  $ cat /proc/net/udp
    sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops
   2007: 00000000:1F90 00000000:0000 07 00000000:00000000 00:00000000 00000000     0        0 72540 2 000000004ede477a 0

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200623230822.3989299-1-yhs@fb.com

1 files changed, 79 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_udp6.c b/tools/testing/selftests/bpf/progs/bpf_iter_udp6.c
new file mode 100644
index 000000000000..c1175a6ecf43
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_udp6.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_endian.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define IPV6_SEQ_DGRAM_HEADER				\
+	"  sl  "					\
+	"local_address                         "	\
+	"remote_address                        "	\
+	"st tx_queue rx_queue tr tm->when retrnsmt"	\
+	"   uid  timeout inode ref pointer drops\n"
+
+static long sock_i_ino(const struct sock *sk)
+{
+	const struct socket *sk_socket = sk->sk_socket;
+	const struct inode *inode;
+	unsigned long ino;
+
+	if (!sk_socket)
+		return 0;
+
+	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
+	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	return ino;
+}
+
+SEC("iter/udp")
+int dump_udp6(struct bpf_iter__udp *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct udp_sock *udp_sk = ctx->udp_sk;
+	const struct in6_addr *dest, *src;
+	struct udp6_sock *udp6_sk;
+	struct inet_sock *inet;
+	__u16 srcp, destp;
+	__u32 seq_num;
+	int rqueue;
+
+	if (udp_sk == (void *)0)
+		return 0;
+
+	seq_num = ctx->meta->seq_num;
+	if (seq_num == 0)
+		BPF_SEQ_PRINTF(seq, IPV6_SEQ_DGRAM_HEADER);
+
+	udp6_sk = bpf_skc_to_udp6_sock(udp_sk);
+	if (udp6_sk == (void *)0)
+		return 0;
+
+	inet = &udp_sk->inet;
+	srcp = bpf_ntohs(inet->inet_sport);
+	destp = bpf_ntohs(inet->inet_dport);
+	rqueue = inet->sk.sk_rmem_alloc.counter - udp_sk->forward_deficit;
+	dest  = &inet->sk.sk_v6_daddr;
+	src   = &inet->sk.sk_v6_rcv_saddr;
+
+	BPF_SEQ_PRINTF(seq, "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X ",
+		       ctx->bucket,
+		       src->s6_addr32[0], src->s6_addr32[1],
+		       src->s6_addr32[2], src->s6_addr32[3], srcp,
+		       dest->s6_addr32[0], dest->s6_addr32[1],
+		       dest->s6_addr32[2], dest->s6_addr32[3], destp);
+
+	BPF_SEQ_PRINTF(seq, "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %u\n",
+		       inet->sk.sk_state,
+		       inet->sk.sk_wmem_alloc.refs.counter - 1,
+		       rqueue,
+		       0, 0L, 0, ctx->uid, 0,
+		       sock_i_ino(&inet->sk),
+		       inet->sk.sk_refcnt.refs.counter, udp_sk,
+		       inet->sk.sk_drops.counter);
+
+	return 0;
+}