tc: add BPF based action

This action provides a possibility to exec custom BPF code.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 218 insertions, 0 deletions

diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index c54c9d9d1ffb..466943551581 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 or 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 679f24ae7f93..7ca2b4e76312 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 000000000000..1bd257e473a9
--- /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");