Crate libbpf_cargo

libbpf-cargo helps you develop and build eBPF (BPF) programs with standard rust tooling.

libbpf-cargo supports two interfaces:

• SkeletonBuilder API, for use with build scripts
• cargo-libbpf cargo subcommand, for use with cargo

The build script interface is recommended over the cargo subcommand interface because:

• once set up, you cannot forget to update the generated skeletons if your source changes
• build scripts are standard practice for projects that include codegen
• newcomers to your project can cargo build and it will “just work”

The following sections in this document describe the cargo-libbpf plugin. See the API reference for documentation on the build script interface.

Configuration

cargo-libbpf consumes the following Cargo.toml configuration options:

[package.metadata.libbpf]
prog_dir = "src/other_bpf_dir"  # default: <manifest_directory>/src/bpf
target_dir = "other_target_dir" # default: <target_dir>/bpf

• prog_dir: path relative to package Cargo.toml to search for bpf progs
• target_dir: path relative to workspace target directory to place compiled bpf progs

Subcommands

build

cargo libbpf build compiles <NAME>.bpf.c C files into corresponding <NAME>.bpf.o ELF object files. Each object file may contain one or more BPF programs, maps, and associated metadata. The object file may then be handed over to libbpf-rs for loading and interaction.

cargo-libbpf-build enforces a few conventions:

• source file names must be in the <NAME>.bpf.c format
• object file names will be generated in <NAME>.bpf.o format
• there may not be any two identical <NAME>.bpf.c file names in any two projects in a cargo workspace

gen

cargo libbpf gen generates a skeleton module for each BPF object file in the project. Each <NAME>.bpf.o object file will have its own module. One mod.rs file is also generated. All output files are placed into package.metadata.libbpf.prog_dir.

Be careful to run cargo-libbpf-build before running cargo-libbpf-gen. cargo-libbpf-gen reads object files from package.metadata.libbpf.target_dir.

make

cargo libbpf make sequentially runs cargo-libbpf-build, cargo-libbpf-gen, and cargo build. This is a convenience command so you don’t forget any steps. Alternatively, you could write a Makefile for your project.

Modules

util

Utility functionality for working with generated skeletons.

Structs

SkeletonBuilder

SkeletonBuilder builds and generates a single skeleton.