tools/bpf: selftests: Add iterator programs for ipv6_route and netlink

Two bpf programs are added in this patch for netlink and ipv6_route
target. On my VM, I am able to achieve identical
results compared to /proc/net/netlink and /proc/net/ipv6_route.

  $ cat /proc/net/netlink
  sk               Eth Pid        Groups   Rmem     Wmem     Dump  Locks    Drops    Inode
  000000002c42d58b 0   0          00000000 0        0        0     2        0        7
  00000000a4e8b5e1 0   1          00000551 0        0        0     2        0        18719
  00000000e1b1c195 4   0          00000000 0        0        0     2        0        16422
  000000007e6b29f9 6   0          00000000 0        0        0     2        0        16424
  ....
  00000000159a170d 15  1862       00000002 0        0        0     2        0        1886
  000000009aca4bc9 15  3918224839 00000002 0        0        0     2        0        19076
  00000000d0ab31d2 15  1          00000002 0        0        0     2        0        18683
  000000008398fb08 16  0          00000000 0        0        0     2        0        27
  $ cat /sys/fs/bpf/my_netlink
  sk               Eth Pid        Groups   Rmem     Wmem     Dump  Locks    Drops    Inode
  000000002c42d58b 0   0          00000000 0        0        0     2        0        7
  00000000a4e8b5e1 0   1          00000551 0        0        0     2        0        18719
  00000000e1b1c195 4   0          00000000 0        0        0     2        0        16422
  000000007e6b29f9 6   0          00000000 0        0        0     2        0        16424
  ....
  00000000159a170d 15  1862       00000002 0        0        0     2        0        1886
  000000009aca4bc9 15  3918224839 00000002 0        0        0     2        0        19076
  00000000d0ab31d2 15  1          00000002 0        0        0     2        0        18683
  000000008398fb08 16  0          00000000 0        0        0     2        0        27

  $ cat /proc/net/ipv6_route
  fe800000000000000000000000000000 40 00000000000000000000000000000000 00 00000000000000000000000000000000 00000100 00000001 00000000 00000001     eth0
  00000000000000000000000000000000 00 00000000000000000000000000000000 00 00000000000000000000000000000000 ffffffff 00000001 00000000 00200200       lo
  00000000000000000000000000000001 80 00000000000000000000000000000000 00 00000000000000000000000000000000 00000000 00000003 00000000 80200001       lo
  fe80000000000000c04b03fffe7827ce 80 00000000000000000000000000000000 00 00000000000000000000000000000000 00000000 00000002 00000000 80200001     eth0
  ff000000000000000000000000000000 08 00000000000000000000000000000000 00 00000000000000000000000000000000 00000100 00000003 00000000 00000001     eth0
  00000000000000000000000000000000 00 00000000000000000000000000000000 00 00000000000000000000000000000000 ffffffff 00000001 00000000 00200200       lo
  $ cat /sys/fs/bpf/my_ipv6_route
  fe800000000000000000000000000000 40 00000000000000000000000000000000 00 00000000000000000000000000000000 00000100 00000001 00000000 00000001     eth0
  00000000000000000000000000000000 00 00000000000000000000000000000000 00 00000000000000000000000000000000 ffffffff 00000001 00000000 00200200       lo
  00000000000000000000000000000001 80 00000000000000000000000000000000 00 00000000000000000000000000000000 00000000 00000003 00000000 80200001       lo
  fe80000000000000c04b03fffe7827ce 80 00000000000000000000000000000000 00 00000000000000000000000000000000 00000000 00000002 00000000 80200001     eth0
  ff000000000000000000000000000000 08 00000000000000000000000000000000 00 00000000000000000000000000000000 00000100 00000003 00000000 00000001     eth0
  00000000000000000000000000000000 00 00000000000000000000000000000000 00 00000000000000000000000000000000 ffffffff 00000001 00000000 00200200       lo
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175921.2477493-1-yhs@fb.com

tools/testing/selftests/bpf/progs/bpf_iter_ipv6_route.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+extern bool CONFIG_IPV6_SUBTREES __kconfig __weak;
+
+#define RTF_GATEWAY		0x0002
+#define IFNAMSIZ		16
+#define fib_nh_gw_family	nh_common.nhc_gw_family
+#define fib_nh_gw6		nh_common.nhc_gw.ipv6
+#define fib_nh_dev		nh_common.nhc_dev
+
+SEC("iter/ipv6_route")
+int dump_ipv6_route(struct bpf_iter__ipv6_route *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct fib6_info *rt = ctx->rt;
+	const struct net_device *dev;
+	struct fib6_nh *fib6_nh;
+	unsigned int flags;
+	struct nexthop *nh;
+
+	if (rt == (void *)0)
+		return 0;
+
+	fib6_nh = &rt->fib6_nh[0];
+	flags = rt->fib6_flags;
+
+	/* FIXME: nexthop_is_multipath is not handled here. */
+	nh = rt->nh;
+	if (rt->nh)
+		fib6_nh = &nh->nh_info->fib6_nh;
+
+	BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
+
+	if (CONFIG_IPV6_SUBTREES)
+		BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_src.addr,
+			       rt->fib6_src.plen);
+	else
+		BPF_SEQ_PRINTF(seq, "00000000000000000000000000000000 00 ");
+
+	if (fib6_nh->fib_nh_gw_family) {
+		flags |= RTF_GATEWAY;
+		BPF_SEQ_PRINTF(seq, "%pi6 ", &fib6_nh->fib_nh_gw6);
+	} else {
+		BPF_SEQ_PRINTF(seq, "00000000000000000000000000000000 ");
+	}
+
+	dev = fib6_nh->fib_nh_dev;
+	if (dev)
+		BPF_SEQ_PRINTF(seq, "%08x %08x %08x %08x %8s\n", rt->fib6_metric,
+			       rt->fib6_ref.refs.counter, 0, flags, dev->name);
+	else
+		BPF_SEQ_PRINTF(seq, "%08x %08x %08x %08x\n", rt->fib6_metric,
+			       rt->fib6_ref.refs.counter, 0, flags);
+
+	return 0;
+}

tools/testing/selftests/bpf/progs/bpf_iter_netlink.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define sk_rmem_alloc	sk_backlog.rmem_alloc
+#define sk_refcnt	__sk_common.skc_refcnt
+
+static inline struct inode *SOCK_INODE(struct socket *socket)
+{
+	return &container_of(socket, struct socket_alloc, socket)->vfs_inode;
+}
+
+SEC("iter/netlink")
+int dump_netlink(struct bpf_iter__netlink *ctx)
+{
+	struct seq_file *seq = ctx->meta->seq;
+	struct netlink_sock *nlk = ctx->sk;
+	unsigned long group, ino;
+	struct inode *inode;
+	struct socket *sk;
+	struct sock *s;
+
+	if (nlk == (void *)0)
+		return 0;
+
+	if (ctx->meta->seq_num == 0)
+		BPF_SEQ_PRINTF(seq, "sk               Eth Pid        Groups   "
+				    "Rmem     Wmem     Dump  Locks    Drops    "
+				    "Inode\n");
+
+	s = &nlk->sk;
+	BPF_SEQ_PRINTF(seq, "%pK %-3d ", s, s->sk_protocol);
+
+	if (!nlk->groups)  {
+		group = 0;
+	} else {
+		/* FIXME: temporary use bpf_probe_read here, needs
+		 * verifier support to do direct access.
+		 */
+		bpf_probe_read(&group, sizeof(group), &nlk->groups[0]);
+	}
+	BPF_SEQ_PRINTF(seq, "%-10u %08x %-8d %-8d %-5d %-8d ",
+		       nlk->portid, (u32)group,
+		       s->sk_rmem_alloc.counter,
+		       s->sk_wmem_alloc.refs.counter - 1,
+		       nlk->cb_running, s->sk_refcnt.refs.counter);
+
+	sk = s->sk_socket;
+	if (!sk) {
+		ino = 0;
+	} else {
+		/* FIXME: container_of inside SOCK_INODE has a forced
+		 * type conversion, and direct access cannot be used
+		 * with current verifier.
+		 */
+		inode = SOCK_INODE(sk);
+		bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	}
+	BPF_SEQ_PRINTF(seq, "%-8u %-8lu\n", s->sk_drops.counter, ino);
+
+	return 0;
+}