[PATCH bpf-next v3 10/21] net: bpf: add netlink and ipv6_route bpf_iter targets

Yonghong Song
2020-05-07T05:39:46Z

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

The net namespace for these targets are the current net
namespace at file open stage, similar to
/proc/net/{netlink,ipv6_route} reference counting
the net namespace at seq_file open stage.

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 bpf_iter.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
fs/proc/proc_net.c | 19 +++++++++
include/linux/proc_fs.h | 3 ++
net/ipv6/ip6_fib.c | 65 +++++++++++++++++++++++++++++-
net/ipv6/route.c | 37 +++++++++++++++++
net/netlink/af_netlink.c | 87 +++++++++++++++++++++++++++++++++++++++-
5 files changed, 207 insertions(+), 4 deletions(-)

diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index 4888c5224442..dba63b2429f0 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -98,6 +98,25 @@ static const struct proc_ops proc_net_seq_ops = {
.proc_release = seq_release_net,
};

+int bpf_iter_init_seq_net(void *priv_data)
+{
+#ifdef CONFIG_NET_NS
+ struct seq_net_private *p = priv_data;
+
+ p->net = get_net(current->nsproxy->net_ns);
+#endif
+ return 0;
+}
+
+void bpf_iter_fini_seq_net(void *priv_data)
+{
+#ifdef CONFIG_NET_NS
+ struct seq_net_private *p = priv_data;
+
+ put_net(p->net);
+#endif
+}
+
struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
struct proc_dir_entry *parent, const struct seq_operations *ops,
unsigned int state_size, void *data)
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 45c05fd9c99d..03953c59807d 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -105,6 +105,9 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
void *data);
extern struct pid *tgid_pidfd_to_pid(const struct file *file);

+extern int bpf_iter_init_seq_net(void *priv_data);
+extern void bpf_iter_fini_seq_net(void *priv_data);
+
#ifdef CONFIG_PROC_PID_ARCH_STATUS
/*
* The architecture which selects CONFIG_PROC_PID_ARCH_STATUS must
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 46ed56719476..a1fcc0ca21af 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;
@@ -2625,7 +2625,7 @@ static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
return w->node && !(w->state == FWS_U && w->node == w->root);
}

-static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
+static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v)
__releases(RCU_BH)
{
struct net *net = seq_file_net(seq);
@@ -2637,6 +2637,67 @@ static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
rcu_read_unlock_bh();
}

+#if IS_BUILTIN(CONFIG_IPV6) && defined(CONFIG_BPF_SYSCALL)
+struct bpf_iter__ipv6_route {
+ __bpf_md_ptr(struct bpf_iter_meta *, meta);
+ __bpf_md_ptr(struct fib6_info *, rt);
+};
+
+static int ipv6_route_prog_seq_show(struct bpf_prog *prog,
+ struct bpf_iter_meta *meta,
+ void *v)
+{
+ struct bpf_iter__ipv6_route ctx;
+
+ ctx.meta = meta;
+ ctx.rt = v;
+ return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+{
+ struct ipv6_route_iter *iter = seq->private;
+ struct bpf_iter_meta meta;
+ struct bpf_prog *prog;
+ int ret;
+
+ meta.seq = seq;
+ prog = bpf_iter_get_info(&meta, false);
+ if (!prog)
+ return ipv6_route_native_seq_show(seq, v);
+
+ ret = ipv6_route_prog_seq_show(prog, &meta, v);
+ iter->w.leaf = NULL;
+
+ return ret;
+}
+
+static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
+{
+ struct bpf_iter_meta meta;
+ struct bpf_prog *prog;
+
+ if (!v) {
+ meta.seq = seq;
+ prog = bpf_iter_get_info(&meta, true);
+ if (prog)
+ (void)ipv6_route_prog_seq_show(prog, &meta, v);
+ }
+
+ ipv6_route_native_seq_stop(seq, v);
+}
+#else
+static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+{
+ return ipv6_route_native_seq_show(seq, v);
+}
+
+static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
+{
+ ipv6_route_native_seq_stop(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 3912aac7854d..25f6d3e619d0 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6393,6 +6393,30 @@ void __init ip6_route_init_special_entries(void)
#endif
}

+#if IS_BUILTIN(CONFIG_IPV6)
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+DEFINE_BPF_ITER_FUNC(ipv6_route, struct bpf_iter_meta *meta, struct fib6_info *rt)
+
+static int __init bpf_iter_register(void)
+{
+ struct bpf_iter_reg reg_info = {
+ .target = "ipv6_route",
+ .seq_ops = &ipv6_route_seq_ops,
+ .init_seq_private = bpf_iter_init_seq_net,
+ .fini_seq_private = bpf_iter_fini_seq_net,
+ .seq_priv_size = sizeof(struct ipv6_route_iter),
+ };
+
+ return bpf_iter_reg_target(&reg_info);
+}
+
+static void bpf_iter_unregister(void)
+{
+ bpf_iter_unreg_target("ipv6_route");
+}
+#endif
+#endif
+
int __init ip6_route_init(void)
{
int ret;
@@ -6455,6 +6479,14 @@ int __init ip6_route_init(void)
if (ret)
goto out_register_late_subsys;

+#if IS_BUILTIN(CONFIG_IPV6)
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+ ret = bpf_iter_register();
+ 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);

@@ -6487,6 +6519,11 @@ int __init ip6_route_init(void)

void ip6_route_cleanup(void)
{
+#if IS_BUILTIN(CONFIG_IPV6)
+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+ bpf_iter_unregister();
+#endif
+#endif
unregister_netdevice_notifier(&ip6_route_dev_notifier);
unregister_pernet_subsys(&ip6_route_net_late_ops);
fib6_rules_cleanup();
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 5ded01ca8b20..33cda9baa979 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2596,7 +2596,7 @@ static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
return __netlink_seq_next(seq);
}

-static void netlink_seq_stop(struct seq_file *seq, void *v)
+static void netlink_native_seq_stop(struct seq_file *seq, void *v)
{
struct nl_seq_iter *iter = seq->private;

@@ -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 +2634,68 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
return 0;
}

+#ifdef CONFIG_BPF_SYSCALL
+struct bpf_iter__netlink {
+ __bpf_md_ptr(struct bpf_iter_meta *, meta);
+ __bpf_md_ptr(struct netlink_sock *, sk);
+};
+
+DEFINE_BPF_ITER_FUNC(netlink, struct bpf_iter_meta *meta, struct netlink_sock *sk)
+
+static int netlink_prog_seq_show(struct bpf_prog *prog,
+ struct bpf_iter_meta *meta,
+ void *v)
+{
+ struct bpf_iter__netlink ctx;
+
+ meta->seq_num--; /* skip SEQ_START_TOKEN */
+ ctx.meta = meta;
+ ctx.sk = nlk_sk((struct sock *)v);
+ return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int netlink_seq_show(struct seq_file *seq, void *v)
+{
+ struct bpf_iter_meta meta;
+ struct bpf_prog *prog;
+
+ meta.seq = seq;
+ prog = bpf_iter_get_info(&meta, false);
+ if (!prog)
+ return netlink_native_seq_show(seq, v);
+
+ if (v != SEQ_START_TOKEN)
+ return netlink_prog_seq_show(prog, &meta, v);
+
+ return 0;
+}
+
+static void netlink_seq_stop(struct seq_file *seq, void *v)
+{
+ struct bpf_iter_meta meta;
+ struct bpf_prog *prog;
+
+ if (!v) {
+ meta.seq = seq;
+ prog = bpf_iter_get_info(&meta, true);
+ if (prog)
+ (void)netlink_prog_seq_show(prog, &meta, v);
+ }
+
+ netlink_native_seq_stop(seq, v);
+}
+#else
+static int netlink_seq_show(struct seq_file *seq, void *v)
+{
+ return netlink_native_seq_show(seq, v);
+}
+
+static void netlink_seq_stop(struct seq_file *seq, void *v)
+{
+ netlink_native_seq_stop(seq, v);
+}
+#endif
+
static const struct seq_operations netlink_seq_ops = {
.start = netlink_seq_start,
.next = netlink_seq_next,
@@ -2740,6 +2802,21 @@ static const struct rhashtable_params netlink_rhashtable_params = {
.automatic_shrinking = true,
};

+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+static int __init bpf_iter_register(void)
+{
+ struct bpf_iter_reg reg_info = {
+ .target = "netlink",
+ .seq_ops = &netlink_seq_ops,
+ .init_seq_private = bpf_iter_init_seq_net,
+ .fini_seq_private = bpf_iter_fini_seq_net,
+ .seq_priv_size = sizeof(struct nl_seq_iter),
+ };
+
+ return bpf_iter_reg_target(&reg_info);
+}
+#endif
+
static int __init netlink_proto_init(void)
{
int i;
@@ -2748,6 +2825,12 @@ static int __init netlink_proto_init(void)
if (err != 0)
goto out;

+#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+ err = bpf_iter_register();
+ if (err)
+ goto out;
+#endif
+
BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof_field(struct sk_buff, cb));

nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
--
2.24.1