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Date:   Wed, 8 Apr 2020 16:25:27 -0700
From:   Yonghong Song <yhs@...com>
To:     Andrii Nakryiko <andriin@...com>, <bpf@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>, <netdev@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>
Subject: [RFC PATCH bpf-next 06/16] bpf: add netlink and ipv6_route targets

This patch added netlink and ipv6_route targets, using
the same seq_ops (except show()) for /proc/net/{netlink,ipv6_route}.

Since module is not supported for now, ipv6_route is
supported only if the IPV6 is built-in, i.e., not compiled
as a module. The restriction can be lifted once module
is properly supported for bpfdump.

Signed-off-by: Yonghong Song <yhs@...com>
---
 include/linux/bpf.h      |  1 +
 kernel/bpf/dump.c        | 13 ++++++++++
 net/ipv6/ip6_fib.c       | 41 +++++++++++++++++++++++++++++-
 net/ipv6/route.c         | 22 ++++++++++++++++
 net/netlink/af_netlink.c | 54 +++++++++++++++++++++++++++++++++++++++-
 5 files changed, 129 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8171e01ff4be..f7d4269d77b8 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1119,6 +1119,7 @@ int bpf_dump_set_target_info(u32 target_fd, struct bpf_prog *prog);
 int bpf_dump_create(u32 prog_fd, const char __user *dumper_name);
 struct bpf_prog *bpf_dump_get_prog(struct seq_file *seq, u32 priv_data_size,
 				   u64 *seq_num);
+int bpf_dump_run_prog(struct bpf_prog *prog, void *ctx);
 
 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
 int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
diff --git a/kernel/bpf/dump.c b/kernel/bpf/dump.c
index ac6856abb711..4e009b2612c2 100644
--- a/kernel/bpf/dump.c
+++ b/kernel/bpf/dump.c
@@ -412,6 +412,19 @@ struct bpf_prog *bpf_dump_get_prog(struct seq_file *seq, u32 priv_data_size,
 	return extra_data->prog;
 }
 
+int bpf_dump_run_prog(struct bpf_prog *prog, void *ctx)
+{
+	int ret;
+
+	migrate_disable();
+	rcu_read_lock();
+	ret = BPF_PROG_RUN(prog, ctx);
+	rcu_read_unlock();
+	migrate_enable();
+
+	return ret;
+}
+
 int bpf_dump_reg_target(const char *target,
 			const char *target_proto,
 			const struct seq_operations *seq_ops,
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 46ed56719476..0a8dbdcf5f12 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2467,7 +2467,7 @@ void fib6_gc_cleanup(void)
 }
 
 #ifdef CONFIG_PROC_FS
-static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+static int ipv6_route_native_seq_show(struct seq_file *seq, void *v)
 {
 	struct fib6_info *rt = v;
 	struct ipv6_route_iter *iter = seq->private;
@@ -2637,6 +2637,45 @@ static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
 	rcu_read_unlock_bh();
 }
 
+#if IS_BUILTIN(CONFIG_IPV6)
+static int ipv6_route_prog_seq_show(struct bpf_prog *prog, struct seq_file *seq,
+				    u64 seq_num, void *v)
+{
+	struct ipv6_route_iter *iter = seq->private;
+	struct {
+		struct fib6_info *rt;
+		struct seq_file *seq;
+		u64 seq_num;
+	} ctx = {
+		.rt = v,
+		.seq = seq,
+		.seq_num = seq_num,
+	};
+	int ret;
+
+	ret = bpf_dump_run_prog(prog, &ctx);
+	iter->w.leaf = NULL;
+	return ret == 0 ? 0 : -EINVAL;
+}
+
+static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+{
+	struct bpf_prog *prog;
+	u64 seq_num;
+
+	prog = bpf_dump_get_prog(seq, sizeof(struct ipv6_route_iter), &seq_num);
+	if (!prog)
+		return ipv6_route_native_seq_show(seq, v);
+
+	return ipv6_route_prog_seq_show(prog, seq, seq_num, v);
+}
+#else
+static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+{
+	return ipv6_route_native_seq_show(seq, v);
+}
+#endif
+
 const struct seq_operations ipv6_route_seq_ops = {
 	.start	= ipv6_route_seq_start,
 	.next	= ipv6_route_seq_next,
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 310cbddaa533..f3457d9d5a8b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6390,6 +6390,16 @@ void __init ip6_route_init_special_entries(void)
   #endif
 }
 
+#if IS_BUILTIN(CONFIG_IPV6)
+#ifdef CONFIG_PROC_FS
+int __init bpfdump__ipv6_route(struct fib6_info *rt, struct seq_file *seq,
+			       u64 seq_num)
+{
+	return 0;
+}
+#endif
+#endif
+
 int __init ip6_route_init(void)
 {
 	int ret;
@@ -6452,6 +6462,18 @@ int __init ip6_route_init(void)
 	if (ret)
 		goto out_register_late_subsys;
 
+#if IS_BUILTIN(CONFIG_IPV6)
+#ifdef CONFIG_PROC_FS
+	ret = bpf_dump_reg_target("ipv6_route",
+				  "bpfdump__ipv6_route",
+				  &ipv6_route_seq_ops,
+				  sizeof(struct ipv6_route_iter),
+				  BPF_DUMP_SEQ_NET_PRIVATE);
+	if (ret)
+		goto out_register_late_subsys;
+#endif
+#endif
+
 	for_each_possible_cpu(cpu) {
 		struct uncached_list *ul = per_cpu_ptr(&rt6_uncached_list, cpu);
 
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 5ded01ca8b20..b6ab827e8d47 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2607,7 +2607,7 @@ static void netlink_seq_stop(struct seq_file *seq, void *v)
 }
 
 
-static int netlink_seq_show(struct seq_file *seq, void *v)
+static int netlink_native_seq_show(struct seq_file *seq, void *v)
 {
 	if (v == SEQ_START_TOKEN) {
 		seq_puts(seq,
@@ -2634,6 +2634,40 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
 	return 0;
 }
 
+static int netlink_prog_seq_show(struct bpf_prog *prog, struct seq_file *seq,
+				 u64 seq_num, void *v)
+{
+	struct {
+		struct netlink_sock *sk;
+		struct seq_file *seq;
+		u64 seq_num;
+	} ctx = {
+		.seq = seq,
+		.seq_num = seq_num - 1,
+	};
+	int ret = 0;
+
+	if (v == SEQ_START_TOKEN)
+		return 0;
+
+	ctx.sk = nlk_sk((struct sock *)v);
+	ret = bpf_dump_run_prog(prog, &ctx);
+
+	return ret == 0 ? 0 : -EINVAL;
+}
+
+static int netlink_seq_show(struct seq_file *seq, void *v)
+{
+	struct bpf_prog *prog;
+	u64 seq_num;
+
+	prog = bpf_dump_get_prog(seq, sizeof(struct nl_seq_iter), &seq_num);
+	if (!prog)
+		return netlink_native_seq_show(seq, v);
+
+	return netlink_prog_seq_show(prog, seq, seq_num, v);
+}
+
 static const struct seq_operations netlink_seq_ops = {
 	.start  = netlink_seq_start,
 	.next   = netlink_seq_next,
@@ -2740,6 +2774,14 @@ static const struct rhashtable_params netlink_rhashtable_params = {
 	.automatic_shrinking = true,
 };
 
+#ifdef CONFIG_PROC_FS
+int __init bpfdump__netlink(struct netlink_sock *sk, struct seq_file *seq,
+			    u64 seq_num)
+{
+	return 0;
+}
+#endif
+
 static int __init netlink_proto_init(void)
 {
 	int i;
@@ -2764,6 +2806,16 @@ static int __init netlink_proto_init(void)
 		}
 	}
 
+#ifdef CONFIG_PROC_FS
+	err = bpf_dump_reg_target("netlink",
+				  "bpfdump__netlink",
+				  &netlink_seq_ops,
+				  sizeof(struct nl_seq_iter),
+				  BPF_DUMP_SEQ_NET_PRIVATE);
+	if (err)
+		goto out;
+#endif
+
 	netlink_add_usersock_entry();
 
 	sock_register(&netlink_family_ops);
-- 
2.24.1

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