![Daniel Borkmann](/assets/img/avatar_default.png)
We have a small skb_at_tc_ingress() helper for testing for ingress, so make use of it. cls_bpf already uses it and so should act_bpf. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
433 lines
9.7 KiB
C
433 lines
9.7 KiB
C
/*
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* Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/filter.h>
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#include <linux/bpf.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <linux/tc_act/tc_bpf.h>
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#include <net/tc_act/tc_bpf.h>
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#define BPF_TAB_MASK 15
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#define ACT_BPF_NAME_LEN 256
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struct tcf_bpf_cfg {
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struct bpf_prog *filter;
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struct sock_filter *bpf_ops;
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const char *bpf_name;
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u32 bpf_fd;
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u16 bpf_num_ops;
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bool is_ebpf;
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};
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static int bpf_net_id;
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static struct tc_action_ops act_bpf_ops;
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static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
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struct tcf_result *res)
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{
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bool at_ingress = skb_at_tc_ingress(skb);
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struct tcf_bpf *prog = to_bpf(act);
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struct bpf_prog *filter;
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int action, filter_res;
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tcf_lastuse_update(&prog->tcf_tm);
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bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
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rcu_read_lock();
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filter = rcu_dereference(prog->filter);
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if (at_ingress) {
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__skb_push(skb, skb->mac_len);
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bpf_compute_data_end(skb);
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filter_res = BPF_PROG_RUN(filter, skb);
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__skb_pull(skb, skb->mac_len);
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} else {
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bpf_compute_data_end(skb);
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filter_res = BPF_PROG_RUN(filter, skb);
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}
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rcu_read_unlock();
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/* A BPF program may overwrite the default action opcode.
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* Similarly as in cls_bpf, if filter_res == -1 we use the
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* default action specified from tc.
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*
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* In case a different well-known TC_ACT opcode has been
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* returned, it will overwrite the default one.
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*
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* For everything else that is unkown, TC_ACT_UNSPEC is
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* returned.
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*/
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switch (filter_res) {
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case TC_ACT_PIPE:
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case TC_ACT_RECLASSIFY:
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case TC_ACT_OK:
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case TC_ACT_REDIRECT:
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action = filter_res;
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break;
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case TC_ACT_SHOT:
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action = filter_res;
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qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats));
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break;
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case TC_ACT_UNSPEC:
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action = prog->tcf_action;
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break;
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default:
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action = TC_ACT_UNSPEC;
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break;
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}
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return action;
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}
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static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog)
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{
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return !prog->bpf_ops;
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}
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static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog,
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struct sk_buff *skb)
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{
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struct nlattr *nla;
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if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops))
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return -EMSGSIZE;
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nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops *
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sizeof(struct sock_filter));
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if (nla == NULL)
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return -EMSGSIZE;
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memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla));
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return 0;
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}
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static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog,
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struct sk_buff *skb)
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{
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if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd))
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return -EMSGSIZE;
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if (prog->bpf_name &&
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nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name))
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return -EMSGSIZE;
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return 0;
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}
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static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act,
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int bind, int ref)
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{
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unsigned char *tp = skb_tail_pointer(skb);
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struct tcf_bpf *prog = to_bpf(act);
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struct tc_act_bpf opt = {
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.index = prog->tcf_index,
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.refcnt = prog->tcf_refcnt - ref,
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.bindcnt = prog->tcf_bindcnt - bind,
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.action = prog->tcf_action,
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};
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struct tcf_t tm;
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int ret;
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if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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if (tcf_bpf_is_ebpf(prog))
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ret = tcf_bpf_dump_ebpf_info(prog, skb);
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else
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ret = tcf_bpf_dump_bpf_info(prog, skb);
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if (ret)
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goto nla_put_failure;
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tcf_tm_dump(&tm, &prog->tcf_tm);
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if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm,
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TCA_ACT_BPF_PAD))
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, tp);
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return -1;
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}
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static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = {
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[TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) },
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[TCA_ACT_BPF_FD] = { .type = NLA_U32 },
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[TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING,
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.len = ACT_BPF_NAME_LEN },
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[TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 },
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[TCA_ACT_BPF_OPS] = { .type = NLA_BINARY,
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.len = sizeof(struct sock_filter) * BPF_MAXINSNS },
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};
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static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
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{
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struct sock_filter *bpf_ops;
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struct sock_fprog_kern fprog_tmp;
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struct bpf_prog *fp;
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u16 bpf_size, bpf_num_ops;
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int ret;
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bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]);
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if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0)
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return -EINVAL;
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bpf_size = bpf_num_ops * sizeof(*bpf_ops);
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if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS]))
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return -EINVAL;
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bpf_ops = kzalloc(bpf_size, GFP_KERNEL);
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if (bpf_ops == NULL)
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return -ENOMEM;
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memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size);
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fprog_tmp.len = bpf_num_ops;
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fprog_tmp.filter = bpf_ops;
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ret = bpf_prog_create(&fp, &fprog_tmp);
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if (ret < 0) {
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kfree(bpf_ops);
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return ret;
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}
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cfg->bpf_ops = bpf_ops;
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cfg->bpf_num_ops = bpf_num_ops;
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cfg->filter = fp;
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cfg->is_ebpf = false;
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return 0;
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}
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static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg)
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{
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struct bpf_prog *fp;
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char *name = NULL;
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u32 bpf_fd;
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bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]);
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fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT);
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if (IS_ERR(fp))
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return PTR_ERR(fp);
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if (tb[TCA_ACT_BPF_NAME]) {
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name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]),
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nla_len(tb[TCA_ACT_BPF_NAME]),
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GFP_KERNEL);
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if (!name) {
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bpf_prog_put(fp);
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return -ENOMEM;
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}
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}
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cfg->bpf_fd = bpf_fd;
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cfg->bpf_name = name;
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cfg->filter = fp;
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cfg->is_ebpf = true;
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return 0;
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}
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static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
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{
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if (cfg->is_ebpf)
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bpf_prog_put(cfg->filter);
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else
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bpf_prog_destroy(cfg->filter);
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kfree(cfg->bpf_ops);
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kfree(cfg->bpf_name);
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}
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static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog,
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struct tcf_bpf_cfg *cfg)
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{
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cfg->is_ebpf = tcf_bpf_is_ebpf(prog);
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/* updates to prog->filter are prevented, since it's called either
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* with rtnl lock or during final cleanup in rcu callback
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*/
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cfg->filter = rcu_dereference_protected(prog->filter, 1);
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cfg->bpf_ops = prog->bpf_ops;
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cfg->bpf_name = prog->bpf_name;
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}
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static int tcf_bpf_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **act,
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int replace, int bind)
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{
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struct tc_action_net *tn = net_generic(net, bpf_net_id);
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struct nlattr *tb[TCA_ACT_BPF_MAX + 1];
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struct tcf_bpf_cfg cfg, old;
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struct tc_act_bpf *parm;
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struct tcf_bpf *prog;
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bool is_bpf, is_ebpf;
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int ret, res = 0;
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if (!nla)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy);
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if (ret < 0)
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return ret;
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if (!tb[TCA_ACT_BPF_PARMS])
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return -EINVAL;
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parm = nla_data(tb[TCA_ACT_BPF_PARMS]);
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if (!tcf_hash_check(tn, parm->index, act, bind)) {
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ret = tcf_hash_create(tn, parm->index, est, act,
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&act_bpf_ops, bind, true);
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if (ret < 0)
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return ret;
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res = ACT_P_CREATED;
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} else {
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/* Don't override defaults. */
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if (bind)
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return 0;
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tcf_hash_release(*act, bind);
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if (!replace)
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return -EEXIST;
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}
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is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS];
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is_ebpf = tb[TCA_ACT_BPF_FD];
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if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) {
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ret = -EINVAL;
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goto out;
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}
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memset(&cfg, 0, sizeof(cfg));
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ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) :
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tcf_bpf_init_from_efd(tb, &cfg);
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if (ret < 0)
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goto out;
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prog = to_bpf(*act);
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ASSERT_RTNL();
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if (res != ACT_P_CREATED)
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tcf_bpf_prog_fill_cfg(prog, &old);
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prog->bpf_ops = cfg.bpf_ops;
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prog->bpf_name = cfg.bpf_name;
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if (cfg.bpf_num_ops)
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prog->bpf_num_ops = cfg.bpf_num_ops;
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if (cfg.bpf_fd)
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prog->bpf_fd = cfg.bpf_fd;
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prog->tcf_action = parm->action;
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rcu_assign_pointer(prog->filter, cfg.filter);
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if (res == ACT_P_CREATED) {
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tcf_hash_insert(tn, *act);
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} else {
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/* make sure the program being replaced is no longer executing */
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synchronize_rcu();
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tcf_bpf_cfg_cleanup(&old);
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}
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return res;
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out:
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if (res == ACT_P_CREATED)
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tcf_hash_cleanup(*act, est);
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return ret;
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}
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static void tcf_bpf_cleanup(struct tc_action *act, int bind)
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{
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struct tcf_bpf_cfg tmp;
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tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp);
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tcf_bpf_cfg_cleanup(&tmp);
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}
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static int tcf_bpf_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops)
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{
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struct tc_action_net *tn = net_generic(net, bpf_net_id);
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return tcf_generic_walker(tn, skb, cb, type, ops);
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}
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static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index)
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{
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struct tc_action_net *tn = net_generic(net, bpf_net_id);
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return tcf_hash_search(tn, a, index);
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}
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static struct tc_action_ops act_bpf_ops __read_mostly = {
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.kind = "bpf",
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.type = TCA_ACT_BPF,
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.owner = THIS_MODULE,
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.act = tcf_bpf,
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.dump = tcf_bpf_dump,
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.cleanup = tcf_bpf_cleanup,
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.init = tcf_bpf_init,
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.walk = tcf_bpf_walker,
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.lookup = tcf_bpf_search,
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.size = sizeof(struct tcf_bpf),
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};
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static __net_init int bpf_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, bpf_net_id);
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return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK);
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}
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static void __net_exit bpf_exit_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, bpf_net_id);
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tc_action_net_exit(tn);
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}
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static struct pernet_operations bpf_net_ops = {
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.init = bpf_init_net,
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.exit = bpf_exit_net,
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.id = &bpf_net_id,
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.size = sizeof(struct tc_action_net),
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};
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static int __init bpf_init_module(void)
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{
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return tcf_register_action(&act_bpf_ops, &bpf_net_ops);
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}
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static void __exit bpf_cleanup_module(void)
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{
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tcf_unregister_action(&act_bpf_ops, &bpf_net_ops);
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}
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module_init(bpf_init_module);
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module_exit(bpf_cleanup_module);
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MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
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MODULE_DESCRIPTION("TC BPF based action");
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MODULE_LICENSE("GPL v2");
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