[RFC PATCH bpf-next 06/16] bpf: add netlink and ipv6_route targets

Yonghong Song
2020-04-08T23:25:41Z

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@fb.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