Florian Westphal 84601d6ee6 bpf: add bpf_link support for BPF_NETFILTER programs
Add bpf_link support skeleton.  To keep this reviewable, no bpf program
can be invoked yet, if a program is attached only a c-stub is called and
not the actual bpf program.

Defaults to 'y' if both netfilter and bpf syscall are enabled in kconfig.

Uapi example usage:
	union bpf_attr attr = { };

	attr.link_create.prog_fd = progfd;
	attr.link_create.attach_type = 0; /* unused */
	attr.link_create.netfilter.pf = PF_INET;
	attr.link_create.netfilter.hooknum = NF_INET_LOCAL_IN;
	attr.link_create.netfilter.priority = -128;

	err = bpf(BPF_LINK_CREATE, &attr, sizeof(attr));

... this would attach progfd to ipv4:input hook.

Such hook gets removed automatically if the calling program exits.

BPF_NETFILTER program invocation is added in followup change.

NF_HOOK_OP_BPF enum will eventually be read from nfnetlink_hook, it
allows to tell userspace which program is attached at the given hook
when user runs 'nft hook list' command rather than just the priority
and not-very-helpful 'this hook runs a bpf prog but I can't tell which
one'.

Will also be used to disallow registration of two bpf programs with
same priority in a followup patch.

v4: arm32 cmpxchg only supports 32bit operand
    s/prio/priority/
v3: restrict prog attachment to ip/ip6 for now, lets lift restrictions if
    more use cases pop up (arptables, ebtables, netdev ingress/egress etc).

Signed-off-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/20230421170300.24115-2-fw@strlen.de
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-04-21 11:34:14 -07:00
..
2022-12-02 11:25:00 +01:00
2022-12-21 14:31:52 -08:00
2023-03-23 17:18:35 -07:00
2023-02-23 14:00:10 -08:00
2023-02-21 10:45:51 -08:00
2023-02-23 13:49:45 -08:00
2022-08-29 19:47:03 -04:00
2022-01-11 13:08:21 -08:00
2022-09-26 10:13:13 -07:00
2023-02-21 15:27:48 -08:00
2022-11-15 00:42:02 -08:00
2022-12-23 12:00:24 -08:00
2023-02-02 16:26:06 -08:00
2022-12-19 12:33:32 -06:00
2022-06-29 13:07:16 +02:00
2022-12-27 12:52:10 +01:00
2022-10-10 12:49:34 -07:00
2022-02-25 09:36:06 +01:00
2023-02-21 13:34:07 -08:00
2022-08-06 16:38:17 -07:00