Add support for BPF_MAP_TYPE_SK_STORAGE

[alexnovak]

Howdy! Would there be any issues if I took a stab at this?

[Sherlock-Holo]

hello, is there any progress on BPF_MAP_TYPE_SK_STORAGE?

I am trying to use sk_storage map in aya, but I can't load the ebpf program, no matter I use bpf_map_def to define the map or use BTF-defined maps

#[repr(C)]
pub struct SkStore {
    type_: *const [c_int; BPF_MAP_TYPE_SK_STORAGE as _],
    map_flags: *const [c_int; BPF_F_NO_PREALLOC as _],
    key: *const c_int,
    value: *const u32,
    max_entries: *const [c_int; 0],
}

unsafe impl Sync for SkStore {}

#[map]
pub static mut SRC_ADDR_STORE: SkStore = SkStore {
    type_: ptr::null(),
    map_flags: ptr::null(),
    key: ptr::null(),
    value: ptr::null(),
    max_entries: ptr::null(),
};

it always report EINVAL

[Sherlock-Holo]

I found a way to use sk_storage

#[repr(C)]
pub struct SkStore {
    r#type: *const [c_int; BPF_MAP_TYPE_SK_STORAGE as _],
    map_flags: *const [c_int; BPF_F_NO_PREALLOC as _],
    key: *const c_int,
    value: *const u32,
    // max_entries: *const [c_int; 0],
}

unsafe impl Sync for SkStore {}

// #[map]
#[link_section = ".maps"]
#[export_name = "SRC_ADDR_STORE"]
pub static mut SRC_ADDR_STORE: SkStore = SkStore {
    r#type: ptr::null(),
    map_flags: ptr::null(),
    key: ptr::null(),
    value: ptr::null(),
    // max_entries: ptr::null(),
};

that

#[link_section = ".maps"]
#[export_name = "SRC_ADDR_STORE"]

can make sure use .maps section, not legacy maps

then change rustflags rustflags = ["-C", "debuginfo=2", "-C", "link-arg=--btf"] to let bpf-linker add BTF section into bpf elf

aya BpfLoader::allow_unsupported_maps should be used