wuzongyo@xxxxxxxxxxxxxxxx writes:
>> wuzongyo@xxxxxxxxxxxxxxxx writes:
>>
>> > Hi,
>> >
>> > I wrote a simple tc-bpf program like that:
>> >
>> > #include <linux/bpf.h>
>> > #include <linux/pkt_cls.h>
>> > #include <linx/types.h>
>> > #include <bpf/bpf_helpers.h>
>> >
>> > struct {
>> > __uint(type, BPF_MAP_TYPE_HASH);
>> > __uint(max_entries, 1);
>> > __type(key, int);
>> > __type(value, int);
>> > } hmap SEC(".maps");
>> >
>> > SEC("classifier")
>> > int _classifier(struct __sk_buff *skb)
>> > {
>> > int key = 0;
>> > int *val;
>> >
>> > val = bpf_map_lookup_elem(&hmap, &key);
>> > if (!val)
>> > return TC_ACT_OK;
>> > return TC_ACT_OK;
>> > }
>> >
>> > char __license[] SEC("license") = "GPL";
>> >
>> > Then I tried to use tc to load the program:
>> >
>> > tc qdisc add dev eth0 clsact
>> > tc filter add dev eth0 egress bpf da obj test_bpf.o
>> >
>> > But the program loading failed with error messages:
>> > Prog section 'classifier' rejected: Permission denied (13)!
>> > - Type: 3
>> > - Instructions: 9 (0 over limit
>> > - License: GPL
>> >
>> > Verifier analysis:
>> >
>> > Error fetching program/map!
>> > Unable to load program
>> >
>> > I tried to replace the map definition with the following code and the program is loaded successfully!
>> >
>> > struct bpf_map_def SEC("maps") hmap = {
>> > .type = BPF_MAP_TYPE_HASH,
>> > .key_size = sizeof(int),
>> > .value_size = sizeof(int),
>> > .max_entries = 1,
>> > };
>> >
>> > With bpftrace, I can find that the errno -EACCES is returned by function do_check(). But I am still confused what's wrong with it.
>> >
>> > Linux Version: 5.17.0-rc3+ with CONFIG_DEBUG_INFO_BTF=y
>> > TC Version: 5.14.0
>> >
>> > Any suggestion will be appreciated!
>>
>> If the latter works but the former doesn't, my guess would be that
>> iproute2 is compiled without libbpf support (in which case it would not
>> support BTF-defined maps either). If it does have libbpf support, that
>> (and the version of libbpf used) will be included in the output of `tc
>> -v`.
>>
>> You could recompile iproute2 with enable libbpf support enabled, or as
>> Andrii suggests you can write your own loader using libbpf...
>>
>
> It works with recompiled-iproute2. Thanks very much!
Great! You're welcome! :)
-Toke
