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c46646d048
Using routing realms as part of the classifier is quite useful, it can be viewed as a tag for one or multiple routing entries (think of an analogy to net_cls cgroup for processes), set by user space routing daemons or via iproute2 as an indicator for traffic classifiers and later on processed in the eBPF program. Unlike actions, the classifier can inspect device flags and enable netif_keep_dst() if necessary. tc actions don't have that possibility, but in case people know what they are doing, it can be used from there as well (e.g. via devs that must keep dsts by design anyway). If a realm is set, the handler returns the non-zero realm. User space can set the full 32bit realm for the dst. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
554 lines
12 KiB
C
554 lines
12 KiB
C
/*
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* Berkeley Packet Filter based traffic classifier
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*
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* Might be used to classify traffic through flexible, user-defined and
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* possibly JIT-ed BPF filters for traffic control as an alternative to
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* ematches.
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*
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* (C) 2013 Daniel Borkmann <dborkman@redhat.com>
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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 version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/filter.h>
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#include <linux/bpf.h>
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#include <net/rtnetlink.h>
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#include <net/pkt_cls.h>
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#include <net/sock.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
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MODULE_DESCRIPTION("TC BPF based classifier");
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#define CLS_BPF_NAME_LEN 256
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struct cls_bpf_head {
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struct list_head plist;
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u32 hgen;
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struct rcu_head rcu;
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};
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struct cls_bpf_prog {
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struct bpf_prog *filter;
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struct list_head link;
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struct tcf_result res;
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bool exts_integrated;
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struct tcf_exts exts;
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u32 handle;
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union {
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u32 bpf_fd;
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u16 bpf_num_ops;
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};
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struct sock_filter *bpf_ops;
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const char *bpf_name;
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struct tcf_proto *tp;
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struct rcu_head rcu;
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};
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static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
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[TCA_BPF_CLASSID] = { .type = NLA_U32 },
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[TCA_BPF_FLAGS] = { .type = NLA_U32 },
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[TCA_BPF_FD] = { .type = NLA_U32 },
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[TCA_BPF_NAME] = { .type = NLA_NUL_STRING, .len = CLS_BPF_NAME_LEN },
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[TCA_BPF_OPS_LEN] = { .type = NLA_U16 },
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[TCA_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 cls_bpf_exec_opcode(int code)
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{
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switch (code) {
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case TC_ACT_OK:
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case TC_ACT_SHOT:
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case TC_ACT_STOLEN:
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case TC_ACT_REDIRECT:
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case TC_ACT_UNSPEC:
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return code;
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default:
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return TC_ACT_UNSPEC;
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}
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}
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static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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struct tcf_result *res)
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{
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struct cls_bpf_head *head = rcu_dereference_bh(tp->root);
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struct cls_bpf_prog *prog;
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#ifdef CONFIG_NET_CLS_ACT
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bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
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#else
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bool at_ingress = false;
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#endif
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int ret = -1;
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if (unlikely(!skb_mac_header_was_set(skb)))
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return -1;
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/* Needed here for accessing maps. */
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rcu_read_lock();
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list_for_each_entry_rcu(prog, &head->plist, link) {
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int filter_res;
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qdisc_skb_cb(skb)->tc_classid = prog->res.classid;
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if (at_ingress) {
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/* It is safe to push/pull even if skb_shared() */
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__skb_push(skb, skb->mac_len);
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filter_res = BPF_PROG_RUN(prog->filter, skb);
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__skb_pull(skb, skb->mac_len);
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} else {
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filter_res = BPF_PROG_RUN(prog->filter, skb);
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}
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if (prog->exts_integrated) {
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res->class = prog->res.class;
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res->classid = qdisc_skb_cb(skb)->tc_classid;
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ret = cls_bpf_exec_opcode(filter_res);
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if (ret == TC_ACT_UNSPEC)
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continue;
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break;
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}
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if (filter_res == 0)
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continue;
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*res = prog->res;
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if (filter_res != -1)
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res->classid = filter_res;
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ret = tcf_exts_exec(skb, &prog->exts, res);
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if (ret < 0)
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continue;
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break;
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}
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rcu_read_unlock();
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return ret;
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}
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static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog)
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{
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return !prog->bpf_ops;
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}
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static int cls_bpf_init(struct tcf_proto *tp)
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{
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struct cls_bpf_head *head;
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head = kzalloc(sizeof(*head), GFP_KERNEL);
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if (head == NULL)
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return -ENOBUFS;
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INIT_LIST_HEAD_RCU(&head->plist);
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rcu_assign_pointer(tp->root, head);
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return 0;
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}
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static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
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{
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tcf_exts_destroy(&prog->exts);
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if (cls_bpf_is_ebpf(prog))
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bpf_prog_put(prog->filter);
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else
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bpf_prog_destroy(prog->filter);
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kfree(prog->bpf_name);
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kfree(prog->bpf_ops);
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kfree(prog);
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}
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static void __cls_bpf_delete_prog(struct rcu_head *rcu)
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{
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struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
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cls_bpf_delete_prog(prog->tp, prog);
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}
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static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
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{
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struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg;
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list_del_rcu(&prog->link);
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tcf_unbind_filter(tp, &prog->res);
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call_rcu(&prog->rcu, __cls_bpf_delete_prog);
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return 0;
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}
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static bool cls_bpf_destroy(struct tcf_proto *tp, bool force)
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{
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog, *tmp;
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if (!force && !list_empty(&head->plist))
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return false;
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list_for_each_entry_safe(prog, tmp, &head->plist, link) {
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list_del_rcu(&prog->link);
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tcf_unbind_filter(tp, &prog->res);
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call_rcu(&prog->rcu, __cls_bpf_delete_prog);
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}
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RCU_INIT_POINTER(tp->root, NULL);
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kfree_rcu(head, rcu);
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return true;
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}
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static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)
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{
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog;
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unsigned long ret = 0UL;
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if (head == NULL)
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return 0UL;
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list_for_each_entry(prog, &head->plist, link) {
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if (prog->handle == handle) {
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ret = (unsigned long) prog;
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break;
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}
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}
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return ret;
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}
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static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog)
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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_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_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_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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prog->bpf_ops = bpf_ops;
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prog->bpf_num_ops = bpf_num_ops;
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prog->bpf_name = NULL;
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prog->filter = fp;
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return 0;
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}
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static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog,
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const struct tcf_proto *tp)
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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_BPF_FD]);
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fp = bpf_prog_get(bpf_fd);
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if (IS_ERR(fp))
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return PTR_ERR(fp);
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if (fp->type != BPF_PROG_TYPE_SCHED_CLS) {
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bpf_prog_put(fp);
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return -EINVAL;
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}
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if (tb[TCA_BPF_NAME]) {
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name = kmemdup(nla_data(tb[TCA_BPF_NAME]),
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nla_len(tb[TCA_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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prog->bpf_ops = NULL;
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prog->bpf_fd = bpf_fd;
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prog->bpf_name = name;
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prog->filter = fp;
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if (fp->dst_needed)
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netif_keep_dst(qdisc_dev(tp->q));
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return 0;
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}
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static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
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struct cls_bpf_prog *prog,
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unsigned long base, struct nlattr **tb,
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struct nlattr *est, bool ovr)
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{
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bool is_bpf, is_ebpf, have_exts = false;
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struct tcf_exts exts;
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int ret;
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is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS];
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is_ebpf = tb[TCA_BPF_FD];
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if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf))
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return -EINVAL;
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tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE);
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ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr);
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if (ret < 0)
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return ret;
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if (tb[TCA_BPF_FLAGS]) {
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u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]);
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if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) {
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tcf_exts_destroy(&exts);
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return -EINVAL;
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}
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have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT;
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}
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prog->exts_integrated = have_exts;
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ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) :
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cls_bpf_prog_from_efd(tb, prog, tp);
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if (ret < 0) {
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tcf_exts_destroy(&exts);
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return ret;
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}
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if (tb[TCA_BPF_CLASSID]) {
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prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
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tcf_bind_filter(tp, &prog->res, base);
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}
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tcf_exts_change(tp, &prog->exts, &exts);
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return 0;
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}
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static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp,
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struct cls_bpf_head *head)
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{
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unsigned int i = 0x80000000;
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u32 handle;
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do {
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if (++head->hgen == 0x7FFFFFFF)
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head->hgen = 1;
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} while (--i > 0 && cls_bpf_get(tp, head->hgen));
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if (unlikely(i == 0)) {
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pr_err("Insufficient number of handles\n");
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handle = 0;
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} else {
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handle = head->hgen;
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}
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return handle;
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}
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static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
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struct tcf_proto *tp, unsigned long base,
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u32 handle, struct nlattr **tca,
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unsigned long *arg, bool ovr)
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{
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg;
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struct nlattr *tb[TCA_BPF_MAX + 1];
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struct cls_bpf_prog *prog;
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int ret;
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if (tca[TCA_OPTIONS] == NULL)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy);
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if (ret < 0)
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return ret;
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prog = kzalloc(sizeof(*prog), GFP_KERNEL);
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if (!prog)
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return -ENOBUFS;
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tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE);
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if (oldprog) {
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if (handle && oldprog->handle != handle) {
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ret = -EINVAL;
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goto errout;
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}
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}
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if (handle == 0)
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prog->handle = cls_bpf_grab_new_handle(tp, head);
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else
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prog->handle = handle;
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if (prog->handle == 0) {
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ret = -EINVAL;
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goto errout;
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}
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ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr);
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if (ret < 0)
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goto errout;
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if (oldprog) {
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list_replace_rcu(&oldprog->link, &prog->link);
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tcf_unbind_filter(tp, &oldprog->res);
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call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
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} else {
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list_add_rcu(&prog->link, &head->plist);
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}
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*arg = (unsigned long) prog;
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return 0;
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errout:
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kfree(prog);
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return ret;
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}
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static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *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_BPF_OPS_LEN, prog->bpf_num_ops))
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return -EMSGSIZE;
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nla = nla_reserve(skb, TCA_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 cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog,
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struct sk_buff *skb)
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{
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if (nla_put_u32(skb, TCA_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_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 cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
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struct sk_buff *skb, struct tcmsg *tm)
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{
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struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh;
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struct nlattr *nest;
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u32 bpf_flags = 0;
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int ret;
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if (prog == NULL)
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return skb->len;
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tm->tcm_handle = prog->handle;
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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if (prog->res.classid &&
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nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid))
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goto nla_put_failure;
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if (cls_bpf_is_ebpf(prog))
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ret = cls_bpf_dump_ebpf_info(prog, skb);
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else
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ret = cls_bpf_dump_bpf_info(prog, skb);
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if (ret)
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goto nla_put_failure;
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if (tcf_exts_dump(skb, &prog->exts) < 0)
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goto nla_put_failure;
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if (prog->exts_integrated)
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bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT;
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if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags))
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goto nla_put_failure;
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nla_nest_end(skb, nest);
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|
|
if (tcf_exts_dump_stats(skb, &prog->exts) < 0)
|
|
goto nla_put_failure;
|
|
|
|
return skb->len;
|
|
|
|
nla_put_failure:
|
|
nla_nest_cancel(skb, nest);
|
|
return -1;
|
|
}
|
|
|
|
static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
|
|
{
|
|
struct cls_bpf_head *head = rtnl_dereference(tp->root);
|
|
struct cls_bpf_prog *prog;
|
|
|
|
list_for_each_entry(prog, &head->plist, link) {
|
|
if (arg->count < arg->skip)
|
|
goto skip;
|
|
if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
|
|
arg->stop = 1;
|
|
break;
|
|
}
|
|
skip:
|
|
arg->count++;
|
|
}
|
|
}
|
|
|
|
static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
|
|
.kind = "bpf",
|
|
.owner = THIS_MODULE,
|
|
.classify = cls_bpf_classify,
|
|
.init = cls_bpf_init,
|
|
.destroy = cls_bpf_destroy,
|
|
.get = cls_bpf_get,
|
|
.change = cls_bpf_change,
|
|
.delete = cls_bpf_delete,
|
|
.walk = cls_bpf_walk,
|
|
.dump = cls_bpf_dump,
|
|
};
|
|
|
|
static int __init cls_bpf_init_mod(void)
|
|
{
|
|
return register_tcf_proto_ops(&cls_bpf_ops);
|
|
}
|
|
|
|
static void __exit cls_bpf_exit_mod(void)
|
|
{
|
|
unregister_tcf_proto_ops(&cls_bpf_ops);
|
|
}
|
|
|
|
module_init(cls_bpf_init_mod);
|
|
module_exit(cls_bpf_exit_mod);
|