![Cong Wang](/assets/img/avatar_default.png)
Kernel automatically creates a tp for each (kind, protocol, priority) tuple, which has handle 0, when we add a new filter, but it still is left there after we remove our own, unless we don't specify the handle (literally means all the filters under the tuple). For example this one is left: # tc filter show dev eth0 filter parent 8001: protocol arp pref 49152 basic The user-space is hard to clean up these for kernel because filters like u32 are organized in a complex way. So kernel is responsible to remove it after all filters are gone. Each type of filter has its own way to store the filters, so each type has to provide its way to check if all filters are gone. Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Cong Wang <cwang@twopensource.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Acked-by: Jamal Hadi Salim<jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
490 lines
10 KiB
C
490 lines
10 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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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_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_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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int ret;
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list_for_each_entry_rcu(prog, &head->plist, link) {
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int filter_res = BPF_PROG_RUN(prog->filter, skb);
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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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return ret;
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}
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return -1;
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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,
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struct cls_bpf_prog *prog, u32 classid)
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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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prog->res.classid = classid;
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return 0;
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}
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static int cls_bpf_prog_from_efd(struct nlattr **tb,
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struct cls_bpf_prog *prog, u32 classid)
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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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prog->res.classid = classid;
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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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struct tcf_exts exts;
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bool is_bpf, is_ebpf;
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u32 classid;
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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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!tb[TCA_BPF_CLASSID])
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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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classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
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ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog, classid) :
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cls_bpf_prog_from_efd(tb, prog, classid);
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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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tcf_bind_filter(tp, &prog->res, base);
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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(&prog->link, &oldprog->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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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 (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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nla_nest_end(skb, nest);
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if (tcf_exts_dump_stats(skb, &prog->exts) < 0)
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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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nla_nest_cancel(skb, nest);
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return -1;
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}
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static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
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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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list_for_each_entry(prog, &head->plist, link) {
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if (arg->count < arg->skip)
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goto skip;
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if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
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arg->stop = 1;
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break;
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}
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skip:
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arg->count++;
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}
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}
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static struct tcf_proto_ops cls_bpf_ops __read_mostly = {
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.kind = "bpf",
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.owner = THIS_MODULE,
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.classify = cls_bpf_classify,
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.init = cls_bpf_init,
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.destroy = cls_bpf_destroy,
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.get = cls_bpf_get,
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.change = cls_bpf_change,
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.delete = cls_bpf_delete,
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.walk = cls_bpf_walk,
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.dump = cls_bpf_dump,
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};
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static int __init cls_bpf_init_mod(void)
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{
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return register_tcf_proto_ops(&cls_bpf_ops);
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}
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static void __exit cls_bpf_exit_mod(void)
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{
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unregister_tcf_proto_ops(&cls_bpf_ops);
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}
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module_init(cls_bpf_init_mod);
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module_exit(cls_bpf_exit_mod);
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