On Fri, May 26, 2023 at 5:11 AM Florian Westphal <fw@xxxxxxxxx> wrote:
>
> Andrii Nakryiko writes:
>
> And we currently don't have an attach type for NETLINK BPF link.
> Thankfully it's not too late to add it. I see that link_create() in
> kernel/bpf/syscall.c just bypasses attach_type check. We shouldn't
> have done that. Instead we need to add BPF_NETLINK attach type to enum
> bpf_attach_type. And wire all that properly throughout the kernel and
> libbpf itself.
>
> This adds BPF_NETFILTER and uses it. This breaks uabi but this
> wasn't in any non-rc release yet, so it should be fine.
>
> Fixes: 84601d6ee68a ("bpf: add bpf_link support for BPF_NETFILTER programs")
> Suggested-by: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> Link: https://lore.kernel.org/bpf/CAEf4BzZ69YgrQW7DHCJUT_X+GqMq_ZQQPBwopaJJVGFD5=d5Vg@xxxxxxxxxxxxxx/
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 1 +
> kernel/bpf/syscall.c | 4 ++++
> tools/include/uapi/linux/bpf.h | 1 +
> tools/lib/bpf/libbpf.c | 2 +-
> 4 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 1bb11a6ee667..c994ff5b157c 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1035,6 +1035,7 @@ enum bpf_attach_type {
> BPF_TRACE_KPROBE_MULTI,
> BPF_LSM_CGROUP,
> BPF_STRUCT_OPS,
> + BPF_NETFILTER,
> __MAX_BPF_ATTACH_TYPE
> };
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 14f39c1e573e..cc1fc2404406 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2433,6 +2433,10 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
> default:
> return -EINVAL;
> }
> + case BPF_PROG_TYPE_NETFILTER:
> + if (expected_attach_type == BPF_NETFILTER)
> + return 0;
> + return -EINVAL;
> case BPF_PROG_TYPE_SYSCALL:
> case BPF_PROG_TYPE_EXT:
> if (expected_attach_type)
You've missed updating link_create() as well, there is a
case BPF_PROG_TYPE_NETFILTER:
break;
switch case, which should validate that attr->link_create.attach_type
is BPF_NETFILTER
Other than that, it looks good to me, thanks!
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 1bb11a6ee667..c994ff5b157c 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1035,6 +1035,7 @@ enum bpf_attach_type {
> BPF_TRACE_KPROBE_MULTI,
> BPF_LSM_CGROUP,
> BPF_STRUCT_OPS,
> + BPF_NETFILTER,
> __MAX_BPF_ATTACH_TYPE
> };
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index ad1ec893b41b..532a97cf1cc1 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -8712,7 +8712,7 @@ static const struct bpf_sec_def section_defs[] = {
> SEC_DEF("struct_ops+", STRUCT_OPS, 0, SEC_NONE),
> SEC_DEF("struct_ops.s+", STRUCT_OPS, 0, SEC_SLEEPABLE),
> SEC_DEF("sk_lookup", SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
> - SEC_DEF("netfilter", NETFILTER, 0, SEC_NONE),
> + SEC_DEF("netfilter", NETFILTER, BPF_NETFILTER, SEC_NONE),
> };
>
> static size_t custom_sec_def_cnt;
> --
> 2.39.3
>
