linux/net/core/lwt_bpf.c
David S. Miller 1ba982806c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:

====================
pull-request: bpf-next 2018-08-07

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Add cgroup local storage for BPF programs, which provides a fast
   accessible memory for storing various per-cgroup data like number
   of transmitted packets, etc, from Roman.

2) Support bpf_get_socket_cookie() BPF helper in several more program
   types that have a full socket available, from Andrey.

3) Significantly improve the performance of perf events which are
   reported from BPF offload. Also convert a couple of BPF AF_XDP
   samples overto use libbpf, both from Jakub.

4) seg6local LWT provides the End.DT6 action, which allows to
   decapsulate an outer IPv6 header containing a Segment Routing Header.
   Adds this action now to the seg6local BPF interface, from Mathieu.

5) Do not mark dst register as unbounded in MOV64 instruction when
   both src and dst register are the same, from Arthur.

6) Define u_smp_rmb() and u_smp_wmb() to their respective barrier
   instructions on arm64 for the AF_XDP sample code, from Brian.

7) Convert the tcp_client.py and tcp_server.py BPF selftest scripts
   over from Python 2 to Python 3, from Jeremy.

8) Enable BTF build flags to the BPF sample code Makefile, from Taeung.

9) Remove an unnecessary rcu_read_lock() in run_lwt_bpf(), from Taehee.

10) Several improvements to the README.rst from the BPF documentation
    to make it more consistent with RST format, from Tobin.

11) Replace all occurrences of strerror() by calls to strerror_r()
    in libbpf and fix a FORTIFY_SOURCE build error along with it,
    from Thomas.

12) Fix a bug in bpftool's get_btf() function to correctly propagate
    an error via PTR_ERR(), from Yue.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-07 11:02:05 -07:00

398 lines
8.9 KiB
C

/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/bpf.h>
#include <net/lwtunnel.h>
struct bpf_lwt_prog {
struct bpf_prog *prog;
char *name;
};
struct bpf_lwt {
struct bpf_lwt_prog in;
struct bpf_lwt_prog out;
struct bpf_lwt_prog xmit;
int family;
};
#define MAX_PROG_NAME 256
static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt)
{
return (struct bpf_lwt *)lwt->data;
}
#define NO_REDIRECT false
#define CAN_REDIRECT true
static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
struct dst_entry *dst, bool can_redirect)
{
int ret;
/* Preempt disable is needed to protect per-cpu redirect_info between
* BPF prog and skb_do_redirect(). The call_rcu in bpf_prog_put() and
* access to maps strictly require a rcu_read_lock() for protection,
* mixing with BH RCU lock doesn't work.
*/
preempt_disable();
bpf_compute_data_pointers(skb);
ret = bpf_prog_run_save_cb(lwt->prog, skb);
switch (ret) {
case BPF_OK:
break;
case BPF_REDIRECT:
if (unlikely(!can_redirect)) {
pr_warn_once("Illegal redirect return code in prog %s\n",
lwt->name ? : "<unknown>");
ret = BPF_OK;
} else {
ret = skb_do_redirect(skb);
if (ret == 0)
ret = BPF_REDIRECT;
}
break;
case BPF_DROP:
kfree_skb(skb);
ret = -EPERM;
break;
default:
pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
kfree_skb(skb);
ret = -EINVAL;
break;
}
preempt_enable();
return ret;
}
static int bpf_input(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct bpf_lwt *bpf;
int ret;
bpf = bpf_lwt_lwtunnel(dst->lwtstate);
if (bpf->in.prog) {
ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
if (ret < 0)
return ret;
}
if (unlikely(!dst->lwtstate->orig_input)) {
pr_warn_once("orig_input not set on dst for prog %s\n",
bpf->out.name);
kfree_skb(skb);
return -EINVAL;
}
return dst->lwtstate->orig_input(skb);
}
static int bpf_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct bpf_lwt *bpf;
int ret;
bpf = bpf_lwt_lwtunnel(dst->lwtstate);
if (bpf->out.prog) {
ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
if (ret < 0)
return ret;
}
if (unlikely(!dst->lwtstate->orig_output)) {
pr_warn_once("orig_output not set on dst for prog %s\n",
bpf->out.name);
kfree_skb(skb);
return -EINVAL;
}
return dst->lwtstate->orig_output(net, sk, skb);
}
static int xmit_check_hhlen(struct sk_buff *skb)
{
int hh_len = skb_dst(skb)->dev->hard_header_len;
if (skb_headroom(skb) < hh_len) {
int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
return -ENOMEM;
}
return 0;
}
static int bpf_xmit(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct bpf_lwt *bpf;
bpf = bpf_lwt_lwtunnel(dst->lwtstate);
if (bpf->xmit.prog) {
int ret;
ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
switch (ret) {
case BPF_OK:
/* If the header was expanded, headroom might be too
* small for L2 header to come, expand as needed.
*/
ret = xmit_check_hhlen(skb);
if (unlikely(ret))
return ret;
return LWTUNNEL_XMIT_CONTINUE;
case BPF_REDIRECT:
return LWTUNNEL_XMIT_DONE;
default:
return ret;
}
}
return LWTUNNEL_XMIT_CONTINUE;
}
static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
{
if (prog->prog)
bpf_prog_put(prog->prog);
kfree(prog->name);
}
static void bpf_destroy_state(struct lwtunnel_state *lwt)
{
struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
bpf_lwt_prog_destroy(&bpf->in);
bpf_lwt_prog_destroy(&bpf->out);
bpf_lwt_prog_destroy(&bpf->xmit);
}
static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
[LWT_BPF_PROG_FD] = { .type = NLA_U32, },
[LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
.len = MAX_PROG_NAME },
};
static int bpf_parse_prog(struct nlattr *attr, struct bpf_lwt_prog *prog,
enum bpf_prog_type type)
{
struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
struct bpf_prog *p;
int ret;
u32 fd;
ret = nla_parse_nested(tb, LWT_BPF_PROG_MAX, attr, bpf_prog_policy,
NULL);
if (ret < 0)
return ret;
if (!tb[LWT_BPF_PROG_FD] || !tb[LWT_BPF_PROG_NAME])
return -EINVAL;
prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_ATOMIC);
if (!prog->name)
return -ENOMEM;
fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
p = bpf_prog_get_type(fd, type);
if (IS_ERR(p))
return PTR_ERR(p);
prog->prog = p;
return 0;
}
static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
[LWT_BPF_IN] = { .type = NLA_NESTED, },
[LWT_BPF_OUT] = { .type = NLA_NESTED, },
[LWT_BPF_XMIT] = { .type = NLA_NESTED, },
[LWT_BPF_XMIT_HEADROOM] = { .type = NLA_U32 },
};
static int bpf_build_state(struct nlattr *nla,
unsigned int family, const void *cfg,
struct lwtunnel_state **ts,
struct netlink_ext_ack *extack)
{
struct nlattr *tb[LWT_BPF_MAX + 1];
struct lwtunnel_state *newts;
struct bpf_lwt *bpf;
int ret;
if (family != AF_INET && family != AF_INET6)
return -EAFNOSUPPORT;
ret = nla_parse_nested(tb, LWT_BPF_MAX, nla, bpf_nl_policy, extack);
if (ret < 0)
return ret;
if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
return -EINVAL;
newts = lwtunnel_state_alloc(sizeof(*bpf));
if (!newts)
return -ENOMEM;
newts->type = LWTUNNEL_ENCAP_BPF;
bpf = bpf_lwt_lwtunnel(newts);
if (tb[LWT_BPF_IN]) {
newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
BPF_PROG_TYPE_LWT_IN);
if (ret < 0)
goto errout;
}
if (tb[LWT_BPF_OUT]) {
newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
BPF_PROG_TYPE_LWT_OUT);
if (ret < 0)
goto errout;
}
if (tb[LWT_BPF_XMIT]) {
newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
BPF_PROG_TYPE_LWT_XMIT);
if (ret < 0)
goto errout;
}
if (tb[LWT_BPF_XMIT_HEADROOM]) {
u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);
if (headroom > LWT_BPF_MAX_HEADROOM) {
ret = -ERANGE;
goto errout;
}
newts->headroom = headroom;
}
bpf->family = family;
*ts = newts;
return 0;
errout:
bpf_destroy_state(newts);
kfree(newts);
return ret;
}
static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
struct bpf_lwt_prog *prog)
{
struct nlattr *nest;
if (!prog->prog)
return 0;
nest = nla_nest_start(skb, attr);
if (!nest)
return -EMSGSIZE;
if (prog->name &&
nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
return -EMSGSIZE;
return nla_nest_end(skb, nest);
}
static int bpf_fill_encap_info(struct sk_buff *skb, struct lwtunnel_state *lwt)
{
struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 ||
bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 ||
bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
return -EMSGSIZE;
return 0;
}
static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
{
int nest_len = nla_total_size(sizeof(struct nlattr)) +
nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
0;
return nest_len + /* LWT_BPF_IN */
nest_len + /* LWT_BPF_OUT */
nest_len + /* LWT_BPF_XMIT */
0;
}
static int bpf_lwt_prog_cmp(struct bpf_lwt_prog *a, struct bpf_lwt_prog *b)
{
/* FIXME:
* The LWT state is currently rebuilt for delete requests which
* results in a new bpf_prog instance. Comparing names for now.
*/
if (!a->name && !b->name)
return 0;
if (!a->name || !b->name)
return 1;
return strcmp(a->name, b->name);
}
static int bpf_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);
return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) ||
bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) ||
bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
}
static const struct lwtunnel_encap_ops bpf_encap_ops = {
.build_state = bpf_build_state,
.destroy_state = bpf_destroy_state,
.input = bpf_input,
.output = bpf_output,
.xmit = bpf_xmit,
.fill_encap = bpf_fill_encap_info,
.get_encap_size = bpf_encap_nlsize,
.cmp_encap = bpf_encap_cmp,
.owner = THIS_MODULE,
};
static int __init bpf_lwt_init(void)
{
return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
}
subsys_initcall(bpf_lwt_init)