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