@ -162,52 +162,86 @@ pub fn is_program_supported(program_type: ProgramType) -> Result<bool, ProgramEr
/// Note that certain errors are expected and handled internally; only
/// unanticipated failures during probing will result in this error.
pub fn is_map_supported ( map_type : MapType ) -> Result < bool , SyscallError > {
if map_type = = MapType ::Unspecified {
return Ok ( false ) ;
}
// Each `bpf_map_ops` struct contains their own `.map_alloc()` & `.map_alloc_check()` that does
// field validation on map_create.
let ( key_size , value_size , max_entries ) = match map_type {
MapType ::Unspecified = > return Ok ( false ) ,
MapType ::Hash // https://elixir.bootlin.com/linux/v3.19/source/kernel/bpf/hashtab.c#L349
| MapType ::PerCpuHash // https://elixir.bootlin.com/linux/v4.6/source/kernel/bpf/hashtab.c#L726
| MapType ::LruHash // https://elixir.bootlin.com/linux/v4.10/source/kernel/bpf/hashtab.c#L1032
| MapType ::LruPerCpuHash // https://elixir.bootlin.com/linux/v4.10/source/kernel/bpf/hashtab.c#L1133
= > ( 1 , 1 , 1 ) ,
MapType ::Array // https://elixir.bootlin.com/linux/v3.19/source/kernel/bpf/arraymap.c#L138
| MapType ::PerCpuArray // https://elixir.bootlin.com/linux/v4.6/source/kernel/bpf/arraymap.c#L283
= > ( 4 , 1 , 1 ) ,
MapType ::ProgramArray // https://elixir.bootlin.com/linux/v4.2/source/kernel/bpf/arraymap.c#L239
| MapType ::PerfEventArray // https://elixir.bootlin.com/linux/v4.3/source/kernel/bpf/arraymap.c#L312
| MapType ::CgroupArray // https://elixir.bootlin.com/linux/v4.8/source/kernel/bpf/arraymap.c#L562
| MapType ::ArrayOfMaps // https://elixir.bootlin.com/linux/v4.12/source/kernel/bpf/arraymap.c#L595
| MapType ::DevMap // https://elixir.bootlin.com/linux/v4.14/source/kernel/bpf/devmap.c#L360
| MapType ::SockMap // https://elixir.bootlin.com/linux/v4.14/source/kernel/bpf/sockmap.c#L874
| MapType ::CpuMap // https://elixir.bootlin.com/linux/v4.15/source/kernel/bpf/cpumap.c#L589
| MapType ::XskMap // https://elixir.bootlin.com/linux/v4.18/source/kernel/bpf/xskmap.c#L224
| MapType ::ReuseportSockArray // https://elixir.bootlin.com/linux/v4.20/source/kernel/bpf/reuseport_array.c#L357
| MapType ::DevMapHash // https://elixir.bootlin.com/linux/v5.4/source/kernel/bpf/devmap.c#L713
= > ( 4 , 4 , 1 ) ,
MapType ::StackTrace // https://elixir.bootlin.com/linux/v4.6/source/kernel/bpf/stackmap.c#L272
= > ( 4 , 8 , 1 ) ,
MapType ::LpmTrie // https://elixir.bootlin.com/linux/v4.11/source/kernel/bpf/lpm_trie.c#L509
= > ( 8 , 1 , 1 ) ,
MapType ::HashOfMaps // https://elixir.bootlin.com/linux/v4.12/source/kernel/bpf/hashtab.c#L1301
| MapType ::SockHash // https://elixir.bootlin.com/linux/v4.18/source/kernel/bpf/sockmap.c#L2507
= > ( 1 , 4 , 1 ) ,
MapType ::CgroupStorage // https://elixir.bootlin.com/linux/v4.19/source/kernel/bpf/local_storage.c#L246
| MapType ::PerCpuCgroupStorage // https://elixir.bootlin.com/linux/v4.20/source/kernel/bpf/local_storage.c#L313
= > ( 16 , 1 , 0 ) ,
MapType ::Queue // https://elixir.bootlin.com/linux/v4.20/source/kernel/bpf/queue_stack_maps.c#L267
| MapType ::Stack // https://elixir.bootlin.com/linux/v4.20/source/kernel/bpf/queue_stack_maps.c#L280
| MapType ::BloomFilter // https://elixir.bootlin.com/linux/v5.16/source/kernel/bpf/bloom_filter.c#L193
= > ( 0 , 1 , 1 ) ,
MapType ::SkStorage // https://elixir.bootlin.com/linux/v5.2/source/net/core/bpf_sk_storage.c#L779
| MapType ::InodeStorage // https://elixir.bootlin.com/linux/v5.10/source/kernel/bpf/bpf_inode_storage.c#L239
| MapType ::TaskStorage // https://elixir.bootlin.com/linux/v5.11/source/kernel/bpf/bpf_task_storage.c#L285
| MapType ::CgrpStorage // https://elixir.bootlin.com/linux/v6.2/source/kernel/bpf/bpf_cgrp_storage.c#L216
= > ( 4 , 1 , 0 ) ,
MapType ::StructOps // https://elixir.bootlin.com/linux/v5.6/source/kernel/bpf/bpf_struct_ops.c#L607
= > ( 4 , 0 , 1 ) ,
MapType ::RingBuf // https://elixir.bootlin.com/linux/v5.8/source/kernel/bpf/ringbuf.c#L296
| MapType ::UserRingBuf // https://elixir.bootlin.com/linux/v6.1/source/kernel/bpf/ringbuf.c#L356
// `max_entries` required to be multiple of kernel page size & power of 2: https://elixir.bootlin.com/linux/v5.8/source/kernel/bpf/ringbuf.c#L160
= > ( 0 , 0 , page_size ( ) as u32 ) ,
MapType ::Arena // https://elixir.bootlin.com/linux/v6.9/source/kernel/bpf/arena.c#L380
= > ( 0 , 0 , 1 ) ,
} ;
// SAFETY: all-zero byte-pattern valid for `bpf_attr`
let mut attr = unsafe { mem ::zeroed ::< bpf_attr > ( ) } ;
// SAFETY: union access
let u = unsafe { & mut attr . __bindgen_anon_1 } ;
u . map_type = map_type as u32 ;
u . key_size = key_size ;
u . value_size = value_size ;
u . max_entries = max_entries ;
// To pass `map_alloc_check`/`map_alloc`
let key_size = match map_type {
MapType ::LpmTrie | MapType ::CgroupStorage | MapType ::PerCpuCgroupStorage = > 16 ,
MapType ::Queue
| MapType ::Stack
| MapType ::RingBuf
| MapType ::BloomFilter
| MapType ::UserRingBuf
| MapType ::Arena = > 0 ,
_ = > 4 ,
} ;
let value_size = match map_type {
MapType ::StackTrace | MapType ::LpmTrie = > 8 ,
MapType ::RingBuf | MapType ::UserRingBuf | MapType ::Arena = > 0 ,
_ = > 4 ,
} ;
let max_entries = match map_type {
MapType ::CgroupStorage
| MapType ::PerCpuCgroupStorage
| MapType ::SkStorage
| MapType ::InodeStorage
| MapType ::TaskStorage
| MapType ::CgrpStorage = > 0 ,
MapType ::RingBuf | MapType ::UserRingBuf = > page_size ( ) as u32 ,
_ = > 1 ,
} ;
// Ensure that fd doesn't get dropped due to scoping.
let inner_map_fd ;
// Ensure that fd doesn't get dropped due to scoping for for *_of_maps type.
let inner_map_fd : MockableFd ;
match map_type {
// lpm_trie required to not be pre-alloced: https://elixir.bootlin.com/linux/v4.11/source/kernel/bpf/lpm_trie.c#L419
MapType ::LpmTrie = > u . map_flags = BPF_F_NO_PREALLOC ,
// For these types, we aim to intentionally trigger `EBADF` by supplying invalid btf attach
// data to verify the map type's existance. Otherwise, negative support will produce
// `EINVAL` instead.
MapType ::SkStorage
| MapType ::InodeStorage
| MapType ::TaskStorage
| MapType ::CgrpStorage = > {
// These types required to not be pre-alloced:
// - sk_storage: https://elixir.bootlin.com/linux/v5.2/source/net/core/bpf_sk_storage.c#L604
// - inode_storage: https://elixir.bootlin.com/linux/v5.10/source/kernel/bpf/bpf_local_storage.c#L525
// - task_storage: https://elixir.bootlin.com/linux/v5.11/source/kernel/bpf/bpf_local_storage.c#L527
// - cgrp_storage: https://elixir.bootlin.com/linux/v6.2/source/kernel/bpf/bpf_local_storage.c#L539
u . map_flags = BPF_F_NO_PREALLOC ;
// Intentionally trigger `EBADF` from `btf_get_by_fd()`.
// Will trigger `EBADF` from `btf_get_by_fd()` https://elixir.bootlin.com/linux/v5.2/source/kernel/bpf/btf.c#L3428
u . btf_fd = u32 ::MAX ;
u . btf_key_type_id = 1 ;
u . btf_value_type_id = 1 ;
@ -231,23 +265,27 @@ pub fn is_map_supported(map_type: MapType) -> Result<bool, SyscallError> {
u . inner_map_fd = inner_map_fd . as_raw_fd ( ) as u32 ;
}
// We aim to intentionally trigger `ENOTSUPP` by setting an invalid, non-zero
// `btf_vmlinux_value_type_id`. Negative support produce `EINVAL` instead.
MapType ::StructOps = > u . btf_vmlinux_value_type_id = 1 ,
// arena required to be mmapable: https://elixir.bootlin.com/linux/v6.9/source/kernel/bpf/arena.c#L103
MapType ::Arena = > u . map_flags = BPF_F_MMAPABLE ,
_ = > { }
}
u . map_type = map_type as u32 ;
u . key_size = key_size ;
u . value_size = value_size ;
u . max_entries = max_entries ;
// SAFETY: BPF_MAP_CREATE returns a new file descriptor.
let io_error = match unsafe { fd_sys_bpf ( bpf_cmd ::BPF_MAP_CREATE , & mut attr ) } {
Ok ( _ ) = > return Ok ( true ) ,
Err ( io_error ) = > io_error ,
} ;
// sk_storage, struct_ops, inode_storage, task_storage, & cgrp_storage requires further
// examination to verify support.
match io_error . raw_os_error ( ) {
Some ( EINVAL ) = > Ok ( false ) ,
// These types use fields that may not exist at the kernel's current version.
// Supplying `bpf_attr` fields unknown to the kernel triggers `E2BIG` from
// `bpf_check_uarg_tail_zero()` https://elixir.bootlin.com/linux/v4.18/source/kernel/bpf/syscall.c#L71.
Some ( E2BIG )
if matches! (
map_type ,
@ -260,6 +298,10 @@ pub fn is_map_supported(map_type: MapType) -> Result<bool, SyscallError> {
{
Ok ( false )
}
// For these types, `EBADF` from `btf_get_by_fd()` https://elixir.bootlin.com/linux/v5.2/source/kernel/bpf/btf.c#L3428
// indicates that map_create advanced far enough in the validation to recognize the type
// before being rejected.
// Otherwise, negative support produces `EINVAL`, meaning it was immediately rejected.
Some ( EBADF )
if matches! (
map_type ,
@ -271,7 +313,10 @@ pub fn is_map_supported(map_type: MapType) -> Result<bool, SyscallError> {
{
Ok ( true )
}
// `ENOTSUPP` from `bpf_struct_ops_map_alloc()` for struct_ops.
// `ENOTSUPP` from `bpf_struct_ops_map_alloc()` https://elixir.bootlin.com/linux/v5.6/source/kernel/bpf/bpf_struct_ops.c#L557
// indicates that map_create advanced far enough in the validation to recognize the type
// before being rejected.
// Otherwise, negative support produces `EINVAL`, meaning it was immediately rejected.
Some ( 524 ) if map_type = = MapType ::StructOps = > Ok ( true ) ,
_ = > Err ( SyscallError {
call : "bpf_map_create" ,