/* * Berkeley Packet Filter based traffic classifier * * Might be used to classify traffic through flexible, user-defined and * possibly JIT-ed BPF filters for traffic control as an alternative to * ematches. * * (C) 2013 Daniel Borkmann <dborkman@redhat.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/module.h> #include <linux/types.h> #include <linux/skbuff.h> #include <linux/filter.h> #include <linux/bpf.h> #include <net/rtnetlink.h> #include <net/pkt_cls.h> #include <net/sock.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); MODULE_DESCRIPTION("TC BPF based classifier"); #define CLS_BPF_NAME_LEN 256 struct cls_bpf_head { struct list_head plist; u32 hgen; struct rcu_head rcu; }; struct cls_bpf_prog { struct bpf_prog *filter; struct list_head link; struct tcf_result res; bool exts_integrated; struct tcf_exts exts; u32 handle; union { u32 bpf_fd; u16 bpf_num_ops; }; struct sock_filter *bpf_ops; const char *bpf_name; struct tcf_proto *tp; struct rcu_head rcu; }; static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { [TCA_BPF_CLASSID] = { .type = NLA_U32 }, [TCA_BPF_FLAGS] = { .type = NLA_U32 }, [TCA_BPF_FD] = { .type = NLA_U32 }, [TCA_BPF_NAME] = { .type = NLA_NUL_STRING, .len = CLS_BPF_NAME_LEN }, [TCA_BPF_OPS_LEN] = { .type = NLA_U16 }, [TCA_BPF_OPS] = { .type = NLA_BINARY, .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, }; static int cls_bpf_exec_opcode(int code) { switch (code) { case TC_ACT_OK: case TC_ACT_SHOT: case TC_ACT_STOLEN: case TC_ACT_REDIRECT: case TC_ACT_UNSPEC: return code; default: return TC_ACT_UNSPEC; } } static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct tcf_result *res) { struct cls_bpf_head *head = rcu_dereference_bh(tp->root); bool at_ingress = skb_at_tc_ingress(skb); struct cls_bpf_prog *prog; int ret = -1; if (unlikely(!skb_mac_header_was_set(skb))) return -1; /* Needed here for accessing maps. */ rcu_read_lock(); list_for_each_entry_rcu(prog, &head->plist, link) { int filter_res; qdisc_skb_cb(skb)->tc_classid = prog->res.classid; if (at_ingress) { /* It is safe to push/pull even if skb_shared() */ __skb_push(skb, skb->mac_len); bpf_compute_data_end(skb); filter_res = BPF_PROG_RUN(prog->filter, skb); __skb_pull(skb, skb->mac_len); } else { bpf_compute_data_end(skb); filter_res = BPF_PROG_RUN(prog->filter, skb); } if (prog->exts_integrated) { res->class = 0; res->classid = TC_H_MAJ(prog->res.classid) | qdisc_skb_cb(skb)->tc_classid; ret = cls_bpf_exec_opcode(filter_res); if (ret == TC_ACT_UNSPEC) continue; break; } if (filter_res == 0) continue; if (filter_res != -1) { res->class = 0; res->classid = filter_res; } else { *res = prog->res; } ret = tcf_exts_exec(skb, &prog->exts, res); if (ret < 0) continue; break; } rcu_read_unlock(); return ret; } static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) { return !prog->bpf_ops; } static int cls_bpf_init(struct tcf_proto *tp) { struct cls_bpf_head *head; head = kzalloc(sizeof(*head), GFP_KERNEL); if (head == NULL) return -ENOBUFS; INIT_LIST_HEAD_RCU(&head->plist); rcu_assign_pointer(tp->root, head); return 0; } static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) { tcf_exts_destroy(&prog->exts); if (cls_bpf_is_ebpf(prog)) bpf_prog_put(prog->filter); else bpf_prog_destroy(prog->filter); kfree(prog->bpf_name); kfree(prog->bpf_ops); kfree(prog); } static void __cls_bpf_delete_prog(struct rcu_head *rcu) { struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); cls_bpf_delete_prog(prog->tp, prog); } static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) { struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg; list_del_rcu(&prog->link); tcf_unbind_filter(tp, &prog->res); call_rcu(&prog->rcu, __cls_bpf_delete_prog); return 0; } static bool cls_bpf_destroy(struct tcf_proto *tp, bool force) { struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog, *tmp; if (!force && !list_empty(&head->plist)) return false; list_for_each_entry_safe(prog, tmp, &head->plist, link) { list_del_rcu(&prog->link); tcf_unbind_filter(tp, &prog->res); call_rcu(&prog->rcu, __cls_bpf_delete_prog); } RCU_INIT_POINTER(tp->root, NULL); kfree_rcu(head, rcu); return true; } static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) { struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *prog; unsigned long ret = 0UL; if (head == NULL) return 0UL; list_for_each_entry(prog, &head->plist, link) { if (prog->handle == handle) { ret = (unsigned long) prog; break; } } return ret; } static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog) { struct sock_filter *bpf_ops; struct sock_fprog_kern fprog_tmp; struct bpf_prog *fp; u16 bpf_size, bpf_num_ops; int ret; bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]); if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) return -EINVAL; bpf_size = bpf_num_ops * sizeof(*bpf_ops); if (bpf_size != nla_len(tb[TCA_BPF_OPS])) return -EINVAL; bpf_ops = kzalloc(bpf_size, GFP_KERNEL); if (bpf_ops == NULL) return -ENOMEM; memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); fprog_tmp.len = bpf_num_ops; fprog_tmp.filter = bpf_ops; ret = bpf_prog_create(&fp, &fprog_tmp); if (ret < 0) { kfree(bpf_ops); return ret; } prog->bpf_ops = bpf_ops; prog->bpf_num_ops = bpf_num_ops; prog->bpf_name = NULL; prog->filter = fp; return 0; } static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog, const struct tcf_proto *tp) { struct bpf_prog *fp; char *name = NULL; u32 bpf_fd; bpf_fd = nla_get_u32(tb[TCA_BPF_FD]); fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_CLS); if (IS_ERR(fp)) return PTR_ERR(fp); if (tb[TCA_BPF_NAME]) { name = kmemdup(nla_data(tb[TCA_BPF_NAME]), nla_len(tb[TCA_BPF_NAME]), GFP_KERNEL); if (!name) { bpf_prog_put(fp); return -ENOMEM; } } prog->bpf_ops = NULL; prog->bpf_fd = bpf_fd; prog->bpf_name = name; prog->filter = fp; if (fp->dst_needed && !(tp->q->flags & TCQ_F_INGRESS)) netif_keep_dst(qdisc_dev(tp->q)); return 0; } static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, struct cls_bpf_prog *prog, unsigned long base, struct nlattr **tb, struct nlattr *est, bool ovr) { bool is_bpf, is_ebpf, have_exts = false; struct tcf_exts exts; int ret; is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS]; is_ebpf = tb[TCA_BPF_FD]; if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) return -EINVAL; tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr); if (ret < 0) return ret; if (tb[TCA_BPF_FLAGS]) { u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]); if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) { tcf_exts_destroy(&exts); return -EINVAL; } have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT; } prog->exts_integrated = have_exts; ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) : cls_bpf_prog_from_efd(tb, prog, tp); if (ret < 0) { tcf_exts_destroy(&exts); return ret; } if (tb[TCA_BPF_CLASSID]) { prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]); tcf_bind_filter(tp, &prog->res, base); } tcf_exts_change(tp, &prog->exts, &exts); return 0; } static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, struct cls_bpf_head *head) { unsigned int i = 0x80000000; u32 handle; do { if (++head->hgen == 0x7FFFFFFF) head->hgen = 1; } while (--i > 0 && cls_bpf_get(tp, head->hgen)); if (unlikely(i == 0)) { pr_err("Insufficient number of handles\n"); handle = 0; } else { handle = head->hgen; } return handle; } static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, struct tcf_proto *tp, unsigned long base, u32 handle, struct nlattr **tca, unsigned long *arg, bool ovr) { struct cls_bpf_head *head = rtnl_dereference(tp->root); struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; struct nlattr *tb[TCA_BPF_MAX + 1]; struct cls_bpf_prog *prog; int ret; if (tca[TCA_OPTIONS] == NULL) return -EINVAL; ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); if (ret < 0) return ret; prog = kzalloc(sizeof(*prog), GFP_KERNEL); if (!prog) return -ENOBUFS; tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); if (oldprog) { if (handle && oldprog->handle != handle) { ret = -EINVAL; goto errout; } } if (handle == 0) prog->handle = cls_bpf_grab_new_handle(tp, head); else prog->handle = handle; if (prog->handle == 0) { ret = -EINVAL; goto errout; } ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr); if (ret < 0) goto errout; if (oldprog) { list_replace_rcu(&oldprog->link, &prog->link); tcf_unbind_filter(tp, &oldprog->res); call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); } else { list_add_rcu(&prog->link, &head->plist); } *arg = (unsigned long) prog; return 0; errout: kfree(prog); return ret; } static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog, struct sk_buff *skb) { struct nlattr *nla; if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops)) return -EMSGSIZE; nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops * sizeof(struct sock_filter)); if (nla == NULL) return -EMSGSIZE; memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); return 0; } static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog, struct sk_buff *skb) { if (nla_put_u32(skb, TCA_BPF_FD, prog->bpf_fd)) return -EMSGSIZE; if (prog->bpf_name && nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name)) return -EMSGSIZE; return 0; } static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, struct sk_buff *skb, struct tcmsg *tm) { struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; struct nlattr *nest; u32 bpf_flags = 0; int ret; if (prog == NULL) return skb->len; tm->tcm_handle = prog->handle; nest = nla_nest_start(skb, TCA_OPTIONS); if (nest == NULL) goto nla_put_failure; if (prog->res.classid && nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) goto nla_put_failure; if (cls_bpf_is_ebpf(prog)) ret = cls_bpf_dump_ebpf_info(prog, skb); else ret = cls_bpf_dump_bpf_info(prog, skb); if (ret) goto nla_put_failure; if (tcf_exts_dump(skb, &prog->exts) < 0) goto nla_put_failure; if (prog->exts_integrated) bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT; if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags)) goto nla_put_failure; nla_nest_end(skb, nest); 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);