使用Rust编写eBPF程序

参考Aya项目，使用Rust编写eBPF程序，最吸引人的地方在于，只需要一种语言就可以完成用户态程序和内核态程序的编写，体验比较好。

1. 开发环境设置

本文使用的开发环境是Fedora Server 39 ，内核版本是6.5.6-300 ，CPU架构是aarch64。

[root@localhost clash]# uname -a Linux localhost 6.5.6-300.fc39.aarch64 #1 SMP PREEMPT_DYNAMIC Fri Oct 6 19:36:57 UTC 2023 aarch64 GNU/Linux [root@localhost clash]# more /etc/os-release NAME="Fedora Linux" VERSION="39 (Server Edition)" ID=fedora VERSION_ID=39 VERSION_CODENAME="" PLATFORM_ID="platform:f39" PRETTY_NAME="Fedora Linux 39 (Server Edition)" ANSI_COLOR="0;38;2;60;110;180" LOGO=fedora-logo-icon CPE_NAME="cpe:/o:fedoraproject:fedora:39" HOME_URL="https://fedoraproject.org/" DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f39/system-administrators-guide/" SUPPORT_URL="https://ask.fedoraproject.org/" BUG_REPORT_URL="https://bugzilla.redhat.com/" REDHAT_BUGZILLA_PRODUCT="Fedora" REDHAT_BUGZILLA_PRODUCT_VERSION=39 REDHAT_SUPPORT_PRODUCT="Fedora" REDHAT_SUPPORT_PRODUCT_VERSION=39 SUPPORT_END=2024-05-14 VARIANT="Server Edition" VARIANT_ID=server [root@localhost clash]#

1.1 OS依赖安装

dnf install llvm llvm-devel

error: No suitable version of LLVM was found system-wide or pointed to by LLVM_SYS_160_PREFIX. Consider using `llvmenv` to compile an appropriate copy of LLVM, and refer to the llvm-sys documentation for more information. llvm-sys: https://crates.io/crates/llvm-sys llvmenv: https://crates.io/crates/llvmenv --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/llvm-sys-160.1.4/src/lib.rs:490:1 | 490 | / std::compile_error!(concat!( 491 | | "No suitable version of LLVM was found system-wide or pointed 492 | | to by LLVM_SYS_", 493 | | env!("CARGO_PKG_VERSION_MAJOR"), ... | 500 | | llvmenv: https://crates.io/crates/llvmenv" 501 | | )); | |__^ error: could not compile `llvm-sys` (lib) due to previous error warning: build failed, waiting for other jobs to finish... error: failed to compile `bpf-linker v0.9.10`, intermediate artifacts can be found at `/tmp/cargo-installTRuP1E`. To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path. [root@localhost ~]#

1.2 Rust依赖安装

rustup install stable
rustup toolchain install nightly --component rust-src

# arm64架构
cargo install --no-default-features bpf-linker
cargo install cargo-generate

2. 创建eBPF项目

这一步使用cargo以及对应的模板生成项目脚手架。

[root@localhost ~]# cd workspace/
[root@localhost workspace]# pwd
/root/workspace
[root@localhost workspace]# 
[root@localhost workspace]# cargo generate --name xdp-hello -d program_type=xdp https://github.com/aya-rs/aya-template
⚠️   Favorite `https://github.com/aya-rs/aya-template` not found in config, using it as a git repository: https://github.com/aya-rs/aya-template
🔧   program_type: "xdp" (variable provided via CLI)
🔧   Destination: /root/workspace/xdp-hello ...
🔧   project-name: xdp-hello ...
🔧   Generating template ...
🔧   Moving generated files into: `/root/workspace/xdp-hello`...
🔧   Initializing a fresh Git repository
✨   Done! New project created /root/workspace/xdp-hello
[root@localhost workspace]# cd xdp-hello/
[root@localhost xdp-hello]# tree .
.
├── Cargo.toml
├── README.md
├── xdp-hello
│   ├── Cargo.toml
│   └── src
│       └── main.rs
├── xdp-hello-common
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
├── xdp-hello-ebpf
│   ├── Cargo.toml
│   ├── rust-toolchain.toml
│   └── src
│       └── main.rs
└── xtask
    ├── Cargo.toml
    └── src
        ├── build_ebpf.rs
        ├── main.rs
        └── run.rs

9 directories, 13 files
[root@localhost xdp-hello]#

3. 编译运行

这个自动生成的项目可以直接编译运行，但是默认绑定的是eth0网卡，如果网卡不一样需要修改下代码或者在运行时指定网卡名。

3.1 编译

[root@localhost xdp-hello]# cargo xtask run -- -h
warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions
// 省略编译细节
// 省略编译细节
   Compiling xdp-hello v0.1.0 (/root/workspace/xdp-hello/xdp-hello)
    Finished dev [unoptimized + debuginfo] target(s) in 12.37s
Usage: xdp-hello [OPTIONS]

Options:
  -i, --iface <IFACE>  [default: eth0]
  -h, --help           Print help
[root@localhost xdp-hello]#

3.2 运行

方法一：修改xdp-hello/src/main.rs文件中的eth0为自己的网卡名称，执行RUST_LOG=info cargo xtask run。
方法二：使用RUST_LOG=info cargo xtask run -- -i ens160运行。

运行后会看到很多日志，表示这个xdp-hello这个eBPF程序已经正常被加载到内核，并且被接收网络包的事件触发。

[root@localhost xdp-hello]# RUST_LOG=info cargo xtask run
warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions
    Finished dev [unoptimized + debuginfo] target(s) in 0.02s
     Running `target/debug/xtask run`
    Finished dev [optimized] target(s) in 0.04s
warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions
    Finished dev [unoptimized + debuginfo] target(s) in 0.03s
[2024-01-02T08:00:55Z INFO  xdp_hello] Waiting for Ctrl-C...
[2024-01-02T08:00:55Z INFO  xdp_hello] received a packet
[2024-01-02T08:00:55Z INFO  xdp_hello] received a packet
[2024-01-02T08:00:55Z INFO  xdp_hello] received a packet
[2024-01-02T08:00:55Z INFO  xdp_hello] received a packet
[2024-01-02T08:00:55Z INFO  xdp_hello] received a packet

4. 总结

看了Learning eBPF这本书，了解到aya这个项目，之前也学习过一段时间Rust，顺手试了下，上手体检还是非常好的。

对于开发生产级别的eBPF程序，个人还是比较推荐使用C语言和libbpf库或者Rust语言和aya库这种组合。一是单一编程语言可以实现，二是有CORE支持，可以兼顾编程体验和“一次编译到处运行”的效果。

BCC框架作为比较早期的eBPF框架，为了解决一次编译到处运行的问题，需要在运行环境安装一大堆依赖包，相当于是使用的时候才编译，长期来看这种方案不适合推广。

Last modified: 02 May 2024