linux/net/sched/act_bpf.c
Daniel Borkmann a8cb5f556b act_bpf: add initial eBPF support for actions
This work extends the "classic" BPF programmable tc action by extending
its scope also to native eBPF code!

Together with commit e2e9b6541d ("cls_bpf: add initial eBPF support
for programmable classifiers") this adds the facility to implement fully
flexible classifier and actions for tc that can be implemented in a C
subset in user space, "safely" loaded into the kernel, and being run in
native speed when JITed.

Also, since eBPF maps can be shared between eBPF programs, it offers the
possibility that cls_bpf and act_bpf can share data 1) between themselves
and 2) between user space applications. That means that, f.e. customized
runtime statistics can be collected in user space, but also more importantly
classifier and action behaviour could be altered based on map input from
the user space application.

For the remaining details on the workflow and integration, see the cls_bpf
commit e2e9b6541d. Preliminary iproute2 part can be found under [1].

  [1] http://git.breakpoint.cc/cgit/dborkman/iproute2.git/log/?h=ebpf-act

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 19:10:44 -04:00

360 lines
7.8 KiB
C

/*
* 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 <linux/bpf.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
#define ACT_BPF_NAME_LEN 256
struct tcf_bpf_cfg {
struct bpf_prog *filter;
struct sock_filter *bpf_ops;
char *bpf_name;
u32 bpf_fd;
u16 bpf_num_ops;
};
static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
struct tcf_result *res)
{
struct tcf_bpf *prog = act->priv;
int action, filter_res;
spin_lock(&prog->tcf_lock);
prog->tcf_tm.lastuse = jiffies;
bstats_update(&prog->tcf_bstats, skb);
/* Needed here for accessing maps. */
rcu_read_lock();
filter_res = BPF_PROG_RUN(prog->filter, skb);
rcu_read_unlock();
/* A BPF program may overwrite the default action opcode.
* Similarly as in cls_bpf, if filter_res == -1 we use the
* default action specified from tc.
*
* In case a different well-known TC_ACT opcode has been
* returned, it will overwrite the default one.
*
* For everything else that is unkown, TC_ACT_UNSPEC is
* returned.
*/
switch (filter_res) {
case TC_ACT_PIPE:
case TC_ACT_RECLASSIFY:
case TC_ACT_OK:
action = filter_res;
break;
case TC_ACT_SHOT:
action = filter_res;
prog->tcf_qstats.drops++;
break;
case TC_ACT_UNSPEC:
action = prog->tcf_action;
break;
default:
action = TC_ACT_UNSPEC;
break;
}
spin_unlock(&prog->tcf_lock);
return action;
}
static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
{
return !prog->bpf_ops;
}
static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
struct sk_buff *skb)
{
struct nlattr *nla;
if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
return -EMSGSIZE;
nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
sizeof(struct sock_filter));
if (nla == NULL)
return -EMSGSIZE;
memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
return 0;
}
static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
struct sk_buff *skb)
{
if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
return -EMSGSIZE;
if (prog->bpf_name &&
nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
return -EMSGSIZE;
return 0;
}
static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
int bind, int ref)
{
unsigned char *tp = skb_tail_pointer(skb);
struct tcf_bpf *prog = act->priv;
struct tc_act_bpf opt = {
.index = prog->tcf_index,
.refcnt = prog->tcf_refcnt - ref,
.bindcnt = prog->tcf_bindcnt - bind,
.action = prog->tcf_action,
};
struct tcf_t tm;
int ret;
if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
if (tcf_bpf_is_ebpf(prog))
ret = tcf_bpf_dump_ebpf_info(prog, skb);
else
ret = tcf_bpf_dump_bpf_info(prog, skb);
if (ret)
goto nla_put_failure;
tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install);
tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse);
tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires);
if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm))
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_FD] = { .type = NLA_U32 },
[TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, .len = ACT_BPF_NAME_LEN },
[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_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
{
struct sock_filter *bpf_ops;
struct sock_fprog_kern fprog_tmp;
struct bpf_prog *fp;
u16 bpf_size, bpf_num_ops;
int ret;
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);
if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
return -EINVAL;
bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
if (bpf_ops == NULL)
return -ENOMEM;
memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
fprog_tmp.len = bpf_num_ops;
fprog_tmp.filter = bpf_ops;
ret = bpf_prog_create(&fp, &fprog_tmp);
if (ret < 0) {
kfree(bpf_ops);
return ret;
}
cfg->bpf_ops = bpf_ops;
cfg->bpf_num_ops = bpf_num_ops;
cfg->filter = fp;
return 0;
}
static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
{
struct bpf_prog *fp;
char *name = NULL;
u32 bpf_fd;
bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
fp = bpf_prog_get(bpf_fd);
if (IS_ERR(fp))
return PTR_ERR(fp);
if (fp->type != BPF_PROG_TYPE_SCHED_ACT) {
bpf_prog_put(fp);
return -EINVAL;
}
if (tb[TCA_ACT_BPF_NAME]) {
name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
nla_len(tb[TCA_ACT_BPF_NAME]),
GFP_KERNEL);
if (!name) {
bpf_prog_put(fp);
return -ENOMEM;
}
}
cfg->bpf_fd = bpf_fd;
cfg->bpf_name = name;
cfg->filter = fp;
return 0;
}
static int tcf_bpf_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action *act,
int replace, int bind)
{
struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
struct tc_act_bpf *parm;
struct tcf_bpf *prog;
struct tcf_bpf_cfg cfg;
bool is_bpf, is_ebpf;
int ret;
if (!nla)
return -EINVAL;
ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
if (ret < 0)
return ret;
is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
is_ebpf = tb[TCA_ACT_BPF_FD];
if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf) ||
!tb[TCA_ACT_BPF_PARMS])
return -EINVAL;
parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
memset(&cfg, 0, sizeof(cfg));
ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
tcf_bpf_init_from_efd(tb, &cfg);
if (ret < 0)
return ret;
if (!tcf_hash_check(parm->index, act, bind)) {
ret = tcf_hash_create(parm->index, est, act,
sizeof(*prog), bind);
if (ret < 0)
goto destroy_fp;
ret = ACT_P_CREATED;
} else {
/* Don't override defaults. */
if (bind)
goto destroy_fp;
tcf_hash_release(act, bind);
if (!replace) {
ret = -EEXIST;
goto destroy_fp;
}
}
prog = to_bpf(act);
spin_lock_bh(&prog->tcf_lock);
prog->bpf_ops = cfg.bpf_ops;
prog->bpf_name = cfg.bpf_name;
if (cfg.bpf_num_ops)
prog->bpf_num_ops = cfg.bpf_num_ops;
if (cfg.bpf_fd)
prog->bpf_fd = cfg.bpf_fd;
prog->tcf_action = parm->action;
prog->filter = cfg.filter;
spin_unlock_bh(&prog->tcf_lock);
if (ret == ACT_P_CREATED)
tcf_hash_insert(act);
return ret;
destroy_fp:
if (is_ebpf)
bpf_prog_put(cfg.filter);
else
bpf_prog_destroy(cfg.filter);
kfree(cfg.bpf_ops);
kfree(cfg.bpf_name);
return ret;
}
static void tcf_bpf_cleanup(struct tc_action *act, int bind)
{
const struct tcf_bpf *prog = act->priv;
if (tcf_bpf_is_ebpf(prog))
bpf_prog_put(prog->filter);
else
bpf_prog_destroy(prog->filter);
}
static struct tc_action_ops act_bpf_ops __read_mostly = {
.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");