libbpf v1.4.0

User space-side features and APIs

• support for BPF token throughout low-level and high-level APIs (see also LIBBPF_BPF_TOKEN_PATH envvar);
• a bunch of struct_ops functionality added, mostly around handling multi-kernel compatibility using BPF CO-RE principles and approaches:
  • support struct_ops defined in kernel modules;
  • support "flavor" suffixes (___smth) for struct_ops types, allowing to define two incompatible definitions for the same target struct_ops kernel type;
  • support disabling/enabling auto-creation of struct_ops variables (maps):
    • SEC("?.struct_ops") and SEC("?.struct_ops.link") are now supported, default to not auto-create struct_ops map;
    • bpf_map__set_autocreate() is now honored for struct_ops maps;
  • disabling auto-creation of struct_ops variable (map) disables auto-loading of related BPF programs (unless they are shared between multiple struct_ops), which means that disabling struct_ops map creation behaves naturally w.r.t. related BPF programs and doesn't require explicitly disabling them from auto-loading;
  • support struct_ops "shadow type" through BPF skeleton, allowing to set/adjust custom data fields and also set/reset/change specific BPF programs implementing struct_ops' callbacks;
• BPF arena map support;
• BPF cookie support for raw tracepoint BPF programs in attach APIs;
• helpful error messages added to libbpf logs when attempting to use struct bpf_program or struct bpf_map instances there were not loaded or created, respectively;
• SEC("sk_skb/verdict") support;

BPF-side features and APIs

• support global subprog argument tagging:
  • __arg_ctx, __arg_nonnull, __arg_nullable, __arg_trusted, and __arg_arena annotations added;
  • for kprobe/uprobe, and perf_event BPF program types, support fallback logic making __arg_ctx work on older kernels that don't yet support __arg_ctx (i.e., arg:ctx decl tag) annotation natively;
• bpf_core_cast() macro added, improving ergonomics of bpf_rdonly_cast() BPF helper;
• support __arena tagged global variables, which are automatically put into BPF arena map;
• __long() macro added for specifying 64-bit values when declaring BTF-defined maps;
• better GCC-BPF support in BPF CO-RE macros in bpf_core_read.h header;

Bug fixes

• fix faccessat() internal usage, breaking Android versions of libbpf;
• use OPTS_SET() in bpf_xdp_query() for better backward/forward compatibility;
• fix inner map's max_entries setting logic;
• btf_ext__raw_data() and btf__new_split() APIs are added back, they were "lost" during libbpf v1.0 release process;
• ignore DWARF sections in BPF linker sanity checks, improving handling of some corner cases;
• fix potential NULL dereference when handling corrupted ELF files.

Full Changelog: v1.3.0...v1.4.0