[patch net-next v4 1/2] tc: add BPF based action

[patch net-next v4 1/2] tc: add BPF based action

[Jiri Pirko]

This action provides a possibility to exec custom BPF code.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
---
v3->v4:
 - fixed Kconfig typo spotted out by Daniel
 - added some desc to Kconfig suggested by Daniel
 - fixed code flow in tcf_bpf to avoid gotos suggested by Daniel
 - drop retval changed from -1 to 0 as suggested by Daniel and agreed by Alexei
 - added a little comment to tcf_bpf drop code as suggested by Daniel
v2->v3:
 - s/bpf_len/bpf_num_ops/ per DaveM's suggestion
v1->v2:
 - fixed error path in _init
 - added cleanup function to kill filter prog
---
 include/net/tc_act/tc_bpf.h        |  25 +++++
 include/uapi/linux/tc_act/Kbuild   |   1 +
 include/uapi/linux/tc_act/tc_bpf.h |  31 ++++++
 net/sched/Kconfig                  |  12 +++
 net/sched/Makefile                 |   1 +
 net/sched/act_bpf.c                | 205 +++++++++++++++++++++++++++++++++++++
 6 files changed, 275 insertions(+)
 create mode 100644 include/net/tc_act/tc_bpf.h
 create mode 100644 include/uapi/linux/tc_act/tc_bpf.h
 create mode 100644 net/sched/act_bpf.c

diff --git a/include/net/tc_act/tc_bpf.h b/include/net/tc_act/tc_bpf.h
new file mode 100644
index 0000000..86a070f
--- /dev/null
+++ b/include/net/tc_act/tc_bpf.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __NET_TC_BPF_H
+#define __NET_TC_BPF_H
+
+#include <linux/filter.h>
+#include <net/act_api.h>
+
+struct tcf_bpf {
+	struct tcf_common	common;
+	struct bpf_prog		*filter;
+	struct sock_filter	*bpf_ops;
+	u16			bpf_num_ops;
+};
+#define to_bpf(a) \
+	container_of(a->priv, struct tcf_bpf, common)
+
+#endif /* __NET_TC_BPF_H */
diff --git a/include/uapi/linux/tc_act/Kbuild b/include/uapi/linux/tc_act/Kbuild
index b057da2..19d5219 100644
--- a/include/uapi/linux/tc_act/Kbuild
+++ b/include/uapi/linux/tc_act/Kbuild
@@ -8,3 +8,4 @@ header-y += tc_nat.h
 header-y += tc_pedit.h
 header-y += tc_skbedit.h
 header-y += tc_vlan.h
+header-y += tc_bpf.h
diff --git a/include/uapi/linux/tc_act/tc_bpf.h b/include/uapi/linux/tc_act/tc_bpf.h
new file mode 100644
index 0000000..5288bd77
--- /dev/null
+++ b/include/uapi/linux/tc_act/tc_bpf.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __LINUX_TC_BPF_H
+#define __LINUX_TC_BPF_H
+
+#include <linux/pkt_cls.h>
+
+#define TCA_ACT_BPF 13
+
+struct tc_act_bpf {
+	tc_gen;
+};
+
+enum {
+	TCA_ACT_BPF_UNSPEC,
+	TCA_ACT_BPF_TM,
+	TCA_ACT_BPF_PARMS,
+	TCA_ACT_BPF_OPS_LEN,
+	TCA_ACT_BPF_OPS,
+	__TCA_ACT_BPF_MAX,
+};
+#define TCA_ACT_BPF_MAX (__TCA_ACT_BPF_MAX - 1)
+
+#endif
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index c54c9d9..29a0f95 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -698,6 +698,18 @@ config NET_ACT_VLAN
 	  To compile this code as a module, choose M here: the
 	  module will be called act_vlan.
 
+config NET_ACT_BPF
+        tristate "BPF based action"
+        depends on NET_CLS_ACT
+        ---help---
+	  Say Y here to execute BPF code on packets. The BPF code will decide
+	  if the packet should be dropped of not.
+
+	  If unsure, say N.
+
+	  To compile this code as a module, choose M here: the
+	  module will be called act_bpf.
+
 config NET_CLS_IND
 	bool "Incoming device classification"
 	depends on NET_CLS_U32 || NET_CLS_FW
diff --git a/net/sched/Makefile b/net/sched/Makefile
index 679f24a..7ca2b4e 100644
--- a/net/sched/Makefile
+++ b/net/sched/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_NET_ACT_SIMP)	+= act_simple.o
 obj-$(CONFIG_NET_ACT_SKBEDIT)	+= act_skbedit.o
 obj-$(CONFIG_NET_ACT_CSUM)	+= act_csum.o
 obj-$(CONFIG_NET_ACT_VLAN)	+= act_vlan.o
+obj-$(CONFIG_NET_ACT_BPF)	+= act_bpf.o
 obj-$(CONFIG_NET_SCH_FIFO)	+= sch_fifo.o
 obj-$(CONFIG_NET_SCH_CBQ)	+= sch_cbq.o
 obj-$(CONFIG_NET_SCH_HTB)	+= sch_htb.o
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
new file mode 100644
index 0000000..1bd257e
--- /dev/null
+++ b/net/sched/act_bpf.c
@@ -0,0 +1,205 @@
+/*
+ * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
+#include <linux/filter.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+
+#include <linux/tc_act/tc_bpf.h>
+#include <net/tc_act/tc_bpf.h>
+
+#define BPF_TAB_MASK     15
+
+static int tcf_bpf(struct sk_buff *skb, const struct tc_action *a,
+		   struct tcf_result *res)
+{
+	struct tcf_bpf *b = a->priv;
+	int action;
+	int filter_res;
+
+	spin_lock(&b->tcf_lock);
+	b->tcf_tm.lastuse = jiffies;
+	bstats_update(&b->tcf_bstats, skb);
+	action = b->tcf_action;
+
+	filter_res = BPF_PROG_RUN(b->filter, skb);
+	if (filter_res == 0) {
+		/* Return code 0 from the BPF program
+		 * is being interpreted as a drop here.
+		 */
+		action = TC_ACT_SHOT;
+		b->tcf_qstats.drops++;
+	}
+
+	spin_unlock(&b->tcf_lock);
+	return action;
+}
+
+static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *a,
+			int bind, int ref)
+{
+	unsigned char *tp = skb_tail_pointer(skb);
+	struct tcf_bpf *b = a->priv;
+	struct tc_act_bpf opt = {
+		.index    = b->tcf_index,
+		.refcnt   = b->tcf_refcnt - ref,
+		.bindcnt  = b->tcf_bindcnt - bind,
+		.action   = b->tcf_action,
+	};
+	struct tcf_t t;
+	struct nlattr *nla;
+
+	if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
+		goto nla_put_failure;
+
+	if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, b->bpf_num_ops))
+		goto nla_put_failure;
+
+	nla = nla_reserve(skb, TCA_ACT_BPF_OPS, b->bpf_num_ops *
+			  sizeof(struct sock_filter));
+	if (!nla)
+		goto nla_put_failure;
+
+	memcpy(nla_data(nla), b->bpf_ops, nla_len(nla));
+
+	t.install = jiffies_to_clock_t(jiffies - b->tcf_tm.install);
+	t.lastuse = jiffies_to_clock_t(jiffies - b->tcf_tm.lastuse);
+	t.expires = jiffies_to_clock_t(b->tcf_tm.expires);
+	if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(t), &t))
+		goto nla_put_failure;
+	return skb->len;
+
+nla_put_failure:
+	nlmsg_trim(skb, tp);
+	return -1;
+}
+
+static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
+	[TCA_ACT_BPF_PARMS]	= { .len = sizeof(struct tc_act_bpf) },
+	[TCA_ACT_BPF_OPS_LEN]	= { .type = NLA_U16 },
+	[TCA_ACT_BPF_OPS]	= { .type = NLA_BINARY,
+				    .len = sizeof(struct sock_filter) * BPF_MAXINSNS },
+};
+
+static int tcf_bpf_init(struct net *net, struct nlattr *nla,
+			struct nlattr *est, struct tc_action *a,
+			int ovr, int bind)
+{
+	struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
+	struct tc_act_bpf *parm;
+	struct tcf_bpf *b;
+	u16 bpf_size, bpf_num_ops;
+	struct sock_filter *bpf_ops;
+	struct sock_fprog_kern tmp;
+	struct bpf_prog *fp;
+	int ret;
+
+	if (!nla)
+		return -EINVAL;
+
+	ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
+	if (ret < 0)
+		return ret;
+
+	if (!tb[TCA_ACT_BPF_PARMS] ||
+	    !tb[TCA_ACT_BPF_OPS_LEN] || !tb[TCA_ACT_BPF_OPS])
+		return -EINVAL;
+	parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
+
+	bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
+	if (bpf_num_ops	> BPF_MAXINSNS || bpf_num_ops == 0)
+		return -EINVAL;
+
+	bpf_size = bpf_num_ops * sizeof(*bpf_ops);
+	bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
+	if (!bpf_ops)
+		return -ENOMEM;
+
+	memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
+
+	tmp.len = bpf_num_ops;
+	tmp.filter = bpf_ops;
+
+	ret = bpf_prog_create(&fp, &tmp);
+	if (ret)
+		goto free_bpf_ops;
+
+	if (!tcf_hash_check(parm->index, a, bind)) {
+		ret = tcf_hash_create(parm->index, est, a, sizeof(*b), bind);
+		if (ret)
+			goto destroy_fp;
+
+		ret = ACT_P_CREATED;
+	} else {
+		if (bind)
+			goto destroy_fp;
+		tcf_hash_release(a, bind);
+		if (!ovr) {
+			ret = -EEXIST;
+			goto destroy_fp;
+		}
+	}
+
+	b = to_bpf(a);
+	spin_lock_bh(&b->tcf_lock);
+	b->tcf_action = parm->action;
+	b->bpf_num_ops = bpf_num_ops;
+	b->bpf_ops = bpf_ops;
+	b->filter = fp;
+	spin_unlock_bh(&b->tcf_lock);
+
+	if (ret == ACT_P_CREATED)
+		tcf_hash_insert(a);
+	return ret;
+
+destroy_fp:
+	bpf_prog_destroy(fp);
+free_bpf_ops:
+	kfree(bpf_ops);
+	return ret;
+}
+
+static void tcf_bpf_cleanup(struct tc_action *a, int bind)
+{
+	struct tcf_bpf *b = a->priv;
+
+	bpf_prog_destroy(b->filter);
+}
+
+static struct tc_action_ops act_bpf_ops = {
+	.kind =		"bpf",
+	.type =		TCA_ACT_BPF,
+	.owner =	THIS_MODULE,
+	.act =		tcf_bpf,
+	.dump =		tcf_bpf_dump,
+	.cleanup =	tcf_bpf_cleanup,
+	.init =		tcf_bpf_init,
+};
+
+static int __init bpf_init_module(void)
+{
+	return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK);
+}
+
+static void __exit bpf_cleanup_module(void)
+{
+	tcf_unregister_action(&act_bpf_ops);
+}
+
+module_init(bpf_init_module);
+module_exit(bpf_cleanup_module);
+
+MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
+MODULE_DESCRIPTION("TC BPF based action");
+MODULE_LICENSE("GPL v2");
-- 
1.9.3

[patch net-next v4 2/2] tc: cls_bpf: rename bpf_len to bpf_num_ops

[Jiri Pirko]

It was suggested by DaveM to change the name as "len" might indicate
unit bytes.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
---
v3->v4:
 - no change
patch added in v3
---
 net/sched/cls_bpf.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 84c8219..1029923 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -37,7 +37,7 @@ struct cls_bpf_prog {
 	struct tcf_result res;
 	struct list_head link;
 	u32 handle;
-	u16 bpf_len;
+	u16 bpf_num_ops;
 	struct tcf_proto *tp;
 	struct rcu_head rcu;
 };
@@ -160,7 +160,7 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 	struct tcf_exts exts;
 	struct sock_fprog_kern tmp;
 	struct bpf_prog *fp;
-	u16 bpf_size, bpf_len;
+	u16 bpf_size, bpf_num_ops;
 	u32 classid;
 	int ret;
 
@@ -173,13 +173,13 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 		return ret;
 
 	classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
-	bpf_len = nla_get_u16(tb[TCA_BPF_OPS_LEN]);
-	if (bpf_len > BPF_MAXINSNS || bpf_len == 0) {
+	bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]);
+	if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) {
 		ret = -EINVAL;
 		goto errout;
 	}
 
-	bpf_size = bpf_len * sizeof(*bpf_ops);
+	bpf_size = bpf_num_ops * sizeof(*bpf_ops);
 	bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
 	if (bpf_ops == NULL) {
 		ret = -ENOMEM;
@@ -188,14 +188,14 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
 
 	memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size);
 
-	tmp.len = bpf_len;
+	tmp.len = bpf_num_ops;
 	tmp.filter = bpf_ops;
 
 	ret = bpf_prog_create(&fp, &tmp);
 	if (ret)
 		goto errout_free;
 
-	prog->bpf_len = bpf_len;
+	prog->bpf_num_ops = bpf_num_ops;
 	prog->bpf_ops = bpf_ops;
 	prog->filter = fp;
 	prog->res.classid = classid;
@@ -303,10 +303,10 @@ static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
 
 	if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
 		goto nla_put_failure;
-	if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_len))
+	if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops))
 		goto nla_put_failure;
 
-	nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_len *
+	nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops *
 			  sizeof(struct sock_filter));
 	if (nla == NULL)
 		goto nla_put_failure;
-- 
1.9.3

Re: [patch net-next v4 1/2] tc: add BPF based action

[Cong Wang]

On Wed, Jan 14, 2015 at 9:43 AM, Jiri Pirko <jiri@resnulli.us> wrote:
> This action provides a possibility to exec custom BPF code.
>

I still don't like it, sorry, not just for your patch, I never like
cls_bpf either, in terms of the user interface and the duplicated
functionalities: cls_bpf vs u32, act_bpf vs gact.

Ideally we should be able to implement them with the same
interface, transparent to users, I think probably because
the nature of bpf implementation somewhat enforces such
interface everywhere, it is clearly overrated.

(I have no idea about eBPF though.)

Re: [patch net-next v4 1/2] tc: add BPF based action

[Daniel Borkmann]

On 01/14/2015 08:27 PM, Cong Wang wrote:
> On Wed, Jan 14, 2015 at 9:43 AM, Jiri Pirko <jiri@resnulli.us> wrote:
>> This action provides a possibility to exec custom BPF code.
>
> I still don't like it, sorry, not just for your patch, I never like
> cls_bpf either, in terms of the user interface and the duplicated
> functionalities: cls_bpf vs u32, act_bpf vs gact.
...
> Ideally we should be able to implement them with the same
> interface, transparent to users, I think probably because
> the nature of bpf implementation somewhat enforces such
> interface everywhere, it is clearly overrated.

Hmm, I guess you're talking about the interface from tc side, other
than that cls_bpf is also faster when JITed. I can only speak for
cls_bpf here, which is modelled the same way after xt_bpf and takes
low-level BPF opcodes directly or stored somewhere as a file. Not
overly pretty, that's true.

For somewhat higher but still low-level enough description, I've
added bpf_asm for that purpose so you can still have full control
and if that's still too much and you don't care about unsupported
BPF extensions, then the libpcap compiler is your friend. For example,
Willem has added [1] longer time ago which takes tcpdump-like
filters and spills out related opcodes for you, if you don't want
to use tcpdump -ddd directly.

The other possibility would be to have an own internal BPF filter
compiler inside of tc (w/o any external lib dependencies), a thought
lingering in my head for quite some time now. I guess I could scratch
some cycles off from my spare time and start hacking on it.

Other than that, for the eBPF part, there are efforts to upstream
backends to llvm and gcc, afaik, so their produced output could be
passed onwards to tc, similarly as in samples/bpf/ as one possibility
I could imagine.

   [1] http://git.netfilter.org/iptables/tree/utils/nfbpf_compile.c

Re: [patch net-next v4 1/2] tc: add BPF based action

[Gao feng]

On 01/15/2015 01:43 AM, Jiri Pirko wrote:
>  
> +config NET_ACT_BPF
> +        tristate "BPF based action"
> +        depends on NET_CLS_ACT
> +        ---help---
> +	  Say Y here to execute BPF code on packets. The BPF code will decide
> +	  if the packet should be dropped of not.

dropped or not ?