├── .github └── workflows │ ├── build-release-binaries.yaml │ └── go.yml ├── .gitignore ├── LICENSE ├── README.md ├── bin ├── emperium-aarch64 └── emperium-x86_64 ├── ctf.yaml └── eBPF ├── header └── vmlinux.h ├── map ├── go.mod ├── go.sum └── main.go ├── redirect ├── ebpf │ └── redirect.c ├── go.mod ├── go.sum └── main.go └── response ├── ebpf └── response.c ├── go.mod ├── go.sum └── main.go /.github/workflows/build-release-binaries.yaml: -------------------------------------------------------------------------------- 1 | name: goreleaser 2 | 3 | on: 4 | pull_request: 5 | push: 6 | # run only against tags 7 | tags: 8 | - "*" 9 | 10 | permissions: 11 | contents: write 12 | # packages: write 13 | # issues: write 14 | 15 | jobs: 16 | goreleaser: 17 | runs-on: ubuntu-latest 18 | steps: 19 | - name: Checkout 20 | uses: actions/checkout@v4 21 | with: 22 | fetch-depth: 0 23 | - name: Set up Go 24 | uses: actions/setup-go@v5 25 | with: 26 | go-version: stable 27 | # More assembly might be required: Docker logins, GPG, etc. 28 | # It all depends on your needs. 29 | - name: Run GoReleaser 30 | uses: goreleaser/goreleaser-action@v6 31 | with: 32 | # either 'goreleaser' (default) or 'goreleaser-pro' 33 | distribution: goreleaser 34 | # 'latest', 'nightly', or a semver 35 | version: "~> v2" 36 | args: release --clean 37 | env: 38 | GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} -------------------------------------------------------------------------------- /.github/workflows/go.yml: -------------------------------------------------------------------------------- 1 | # This workflow will build a golang project 2 | # For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go 3 | 4 | name: Go 5 | 6 | on: 7 | push: 8 | branches: [ "main" ] 9 | pull_request: 10 | branches: [ "main" ] 11 | 12 | jobs: 13 | 14 | build: 15 | runs-on: ubuntu-latest 16 | steps: 17 | - uses: actions/checkout@v4 18 | 19 | - name: Set up Go 20 | uses: actions/setup-go@v4 21 | with: 22 | go-version: '1.21.3' 23 | 24 | - name: Build 25 | run: cd emperium; go build 26 | 27 | - name: Release 28 | uses: softprops/action-gh-release@v2 29 | with: 30 | files: ./emperium/emperium 31 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | emperium/emperium 2 | eBPF/response/response 3 | emperium/emperium 4 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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Some of the challenges will require use of CLI tools such as `bpftool` and some will require fixing or completing some partial code in order to complete the challenge. 4 | 5 | ## Getting help and solving the CTF 6 | 7 | Please register at the [eBPF slack](https://slack.cilium.io) and join the `#ebpf-summit` & `#ebpf-summit-ctf-spoilers` channels! Here you will find help and clues, and also a place to submit your answers once you've completed the CTF!. 8 | 9 | ## Getting the CTF up and running ! 10 | 11 | The CTF makes use of the [lima](https://github.com/lima-vm/lima) project to simplify the process of creating a virtual machine that will run the CTF. The virtual machine once created will contain: 12 | 13 | - CTF program 14 | - code-server (VS-CODE but accessed through a browser) 15 | - vim 16 | - a `~/ebpf` directory that is filled with the sample code for the challenges 17 | 18 | ## Create the CTF VM 19 | You will need to take the `ctf.yaml` in this repository and start it with `limactl`, this will build and start the virtual machine! 20 | 21 | `limactl start ctf.yaml` 22 | 23 | ## Accessing the VM 24 | 25 | You will need at least two shells in order to access both the `emperium` system and the underlying OS in order to interact with the Kernel and eBPF programs. 26 | 27 | ### First shell 28 | 29 | This will connect to the running system and start `emperium`. 30 | 31 | `limactl shell ctf sudo /tmp/emperium` 32 | 33 | ``` 34 | 35 | ._,. 36 | "..-..pf. 37 | -L ..#' 38 | .+_L ."]# 39 | ,'j' .+.j' -'.__..,.,p. 40 | _~ #..<..0. .J-.''..._f. 41 | .7..#_.. _f. .....-..,'4' 42 | ;' ,#j. T' .. ..J....,'.j' 43 | .' .."^.,-0.,,,,yMMMMM,. ,-.J...+'.j@ 44 | .'.'...' .yMMMMM0M@^='""g.. .'..J..".'.jH 45 | j' .'1' q'^)@@#"^".'"='BNg_...,]_)'...0- 46 | .T ...I. j" .'..+,_.'3#MMM0MggCBf....F. 47 | j/.+'.{..+ '^~'-^~~""""'"""?'"'''1' 48 | .... .y.} '.._-:'_...jf 49 | g-. .Lg' ..,..'-....,'. 50 | .'. .Y^ .....',].._f 51 | ......-f. .-,,.,.-:--&' 52 | .'...'..'_J' 53 | .~......'#' Tie Fighter Manufacturing 54 | '..,,.,_]' Security Systems 55 | .L..'..''. 56 | Data system> Initialising... 57 | Data system> Ready 58 | Security Status> Enabled 59 | Security Lock 1> [ ▮ ] 60 | Security Lock 2> [ ▮ ] 61 | Security Lock 3> [ ▮ ] 62 | ``` 63 | 64 | ### Second shell 65 | 66 | The following line will connect through to the VM using SSH, it will also port forward from inside the VM (port 80) to port `8082` on your local machine. The reason for this is to allow the use of code-server to interact with the `eBPF` 🐝 code. 67 | 68 | `ssh -F $HOME/.lima/ctf/ssh.config -L "*:8082:0.0.0.0:80" lima-ctf` 69 | 70 | To start `code-server` within the VM run the command: 71 | 72 | `PASSWORD=password code-server --bind-addr=0.0.0.0 > /tmp/code.log &`. 73 | 74 | **Additionally**: You may find it makes things a little easier to install some plugins to make things easier, such as the `clangd` extension or the `golang` extension. 75 | 76 | ## Setting up the eBPF code 77 | 78 | All of the code lives within `~/eBPF` and is automatically created when you start the first shell, so if this is missing ensure you're following the instructions. 79 | 80 | ### Code-Server or Vim 81 | 82 | To make life as easy as possible we've packaged both Vim and Code-server for you to create and modify Go and eBPF code. To connect to code-server open a browser and point it to the IP address of the host where the `lima` VM is running (not the CTF VM IP, the IP of the hosting machine itself). Connecting to port `8082` will open code-server that will allow you to work inside the CTF VM. The CTF source code is in your home directory! 83 | 84 | ### Compiling the code 85 | 86 | In each of the folders in `~/eBPF` is some half completed eBPF 🐝 programs. Most of the programs will require running `go generate` in order to compile the C/eBPF source code first before you can run the main go binary. Additionally to run the go programs themselves the easiest approach is to either `go build` and run the resulting binary with `sudo` or the do `go run -exec sudo .`. 87 | 88 | ## The challenge ! 89 | 90 | They are _everywhere_. This is a true infestation. Way worse than the rockmites you had to fight off to defend your giant bees, back in your days as a beekeeper. Worse, even, than the herd of mynocks you found in that asteroid field, when ambushing an Imperial transporter (which turned up to carry no sensitive information, but never mind, they freighted chocolates, and they're delicious). This time, they just won't stop coming. And they're big things, flying fast, with a terrible roar. 91 | 92 | These are TIE Fighters from the Empire. And they're after you. 93 | 94 | Jephen'Tsa is your name, and you've made life tough for the Empire. But this time, Imperials are the ones harassing your team. If they can't pin down the exact location of your Rebel base, they have a gross idea of the area where you're hiding, courtesy of your sworn enemy, the traitor Bajeroff Lake. Armadas of TIEs have been patrolling in the whole constellation, and every mission, every outing has been a pain. Sure, the Rebel Alliance has some of the best pilots in the galaxy, but for each fighter they strike down, five new ships come out of the factory. Your own vessel, the _Yellow Stripe_, is docked for repairs. This is untenable. If you could just stop enemy fighters from coming back... 95 | 96 | As it turns out, an opportunity came up this morning, thanks to the hard work of your friend and ally, Blue Hex. Her utility droid, IP-V6, just brought you to the control room, where Blue Hex explains how her spy network is getting close to disable the whole TIE fighter production lines, no less! She has established a hidden connection to the mainframe in the manufacturing facility, but disabling it requires accessing the core controls of the system, protected by **four** security locks. Oh wait, an alarm erupts! Some TIEs are nearby! Did they find your hideout at last? Blue Hex stops her briefing and jumps into her ship, imitated by the other pilots. 97 | 98 | But your own spacecraft is not ready, and for this time you're grounded. You should as well look into these security locks, to disable the factory. That would be quite an achievement... One more to add to your name? Sit down and relax. The Force is with you. You can do it. Let's start by sending IP-V6 fetch a few more of these delicious chocolates... 99 | 100 | 101 | ### Part 1 - unscramble the message 102 | A hacker from the Zenith system in the employ of the Rebellion managed to get a communication out, whilst the quality was poor technicians managed to enhance enough of the audio to understand that the hacker may have "got it the wrong way around" and that the bpftool might be the best way to fix it. 103 | 104 |
105 | First Clue 106 | 107 | `bpftool` can be used to list all of the maps 108 |
109 | Second Clue 110 | 111 | `bpftool` can dump the contents of a specific map identified by name or ID 112 |
113 | Final Clue 114 | 115 | `bpftool` can update the contents of the specific key/value within a map. 116 |
117 |
118 |
119 | 120 | ### Part 2 - complete the keycodes 121 | Our spies managed to extract one of the vital keycodes from the emperium key vaults, they unfortunately deleted the emperium map in the process. Whilst we now have this data `brRz3HVSVzC6RXrBC2Y7`, we're not sure if this will impact the running `emperium` system. 📂`eBPF/map` (or perhaps this can be done with `bpftool` 🤔) 122 | 123 |
124 | First Clue 125 | 126 | Partially completed code is one way to help you achieve this, you'll need to look at an existing map to understand the key/values 127 |
128 | Second Clue 129 | 130 | An `eBPF` map will only exist as long as a program or file has a reference too it, otherwise it will be garbage collected. 131 |
132 |
133 | 134 | ### Part 3 - get authenticated 135 | An archive taken from a stolen ship has revealed the third security lock is broken due to the authentication being pushed to the wrong port. One of the engineers has managed to put something together, but keeps muttering about "Endianness" and returning traffic. 📂`eBPF/redirect/` 136 | 137 |
138 | First Clue 139 | 140 | Is something generating network traffic on the `lo` interface? 141 |
142 | Second Clue 143 | 144 | In most cases, numbers are carried in network packets in [big-endian](https://en.wikipedia.org/wiki/Endianness#/media/File:32bit-Endianess.svg) byte order, which may differ from the host byte order on a particular machine. So often you may need to convert between host byte order and network byte order. There are bpf helper functions that will allow you to convert between the two. 145 | 146 |
147 | Third Clue 148 | 149 | Changing a destination port will effectively change where traffic is being sent to, although it may confuse the networking stack to suddenly receive a reply to a port that it wasn't expecting... 150 |
151 |
152 |
153 | 154 | ### Part 4 - access the mainframe 155 | A defector has provided most of the code that is needed in order to create a fake `emperium` mainframe, once up this will be able to **"acknowledge"** the `emperium` system. The specialist that wrote most of this was reassigned after breaking his keyboard about a "verifier"? 📂`eBPF/response/` 156 | 157 |
158 | First Clue 159 | 160 | You'll need to modify the partially-complete code so that it passes the eBPF Verifier 161 | 162 |
163 | Second Clue 164 | 165 | There are BPF helper functions for reading bytes out of the kernel's network packet data structure (a.k.a. `skb`) as well as for storing bytes in it. 166 |
167 |
168 | 169 | ## Additional 170 | 171 | You can also run the `/emperium` program locally (with root privileges) on a Linux machine if you don't want to use lima. It will attempt to write the source code to a `eBPF` folder so ensure one doesn't exist in the directory you run the `/emperium` program. 172 | -------------------------------------------------------------------------------- /bin/emperium-aarch64: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/isovalent/eBPF-Summit-2024-CTF/700201b240c7858c389dcb6193991ea818511bdc/bin/emperium-aarch64 -------------------------------------------------------------------------------- /bin/emperium-x86_64: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/isovalent/eBPF-Summit-2024-CTF/700201b240c7858c389dcb6193991ea818511bdc/bin/emperium-x86_64 -------------------------------------------------------------------------------- /ctf.yaml: -------------------------------------------------------------------------------- 1 | # This template requires Lima v0.7.0 or later. 2 | images: 3 | # Try to use release-yyyyMMdd image if available. Note that release-yyyyMMdd will be removed after several months. 4 | - location: "https://cloud-images.ubuntu.com/releases/24.04/release-20240725/ubuntu-24.04-server-cloudimg-amd64.img" 5 | arch: "x86_64" 6 | digest: "sha256:d2377667ea95222330ca2287817403c85178dad397e9fed768a9b4aec79d2a7f" 7 | - location: "https://cloud-images.ubuntu.com/releases/24.04/release-20240725/ubuntu-24.04-server-cloudimg-arm64.img" 8 | arch: "aarch64" 9 | digest: "sha256:2c47dbf04477993ebcd921250b1aab8e582d2fdd03d7576b57d28b6aeeff1427" 10 | # Fallback to the latest release image. 11 | # Hint: run `limactl prune` to invalidate the cache 12 | - location: "https://cloud-images.ubuntu.com/releases/24.04/release/ubuntu-24.04-server-cloudimg-amd64.img" 13 | arch: "x86_64" 14 | - location: "https://cloud-images.ubuntu.com/releases/24.04/release/ubuntu-24.04-server-cloudimg-arm64.img" 15 | arch: "aarch64" 16 | 17 | # containerd is managed by k3s, not by Lima, so the values are set to false here. 18 | containerd: 19 | system: false 20 | user: false 21 | 22 | ### In case you wish to mount your home directory 23 | # mounts: 24 | #- location: "~" 25 | 26 | provision: 27 | - mode: system 28 | script: | 29 | #!/bin/sh 30 | sudo apt-get update; sudo apt-get install -y linux-tools-$(uname -r) libbpf-dev clang vim golang-go git llvm 31 | sudo curl -L https://github.com/isovalent/eBPF-Summit-2024-CTF/raw/main/bin/emperium-$(uname -m) > /tmp/emperium && chmod +x /tmp/emperium 32 | - mode: user 33 | script: | 34 | #!/bin/sh 35 | curl -fsSL https://code-server.dev/install.sh | sh 36 | probes: 37 | - script: | 38 | #!/bin/bash 39 | message: | 40 | Welcome to the eBPF Summit 2024 !! 41 | ------ 42 | In one terminal you can connect to your running instance with the command: 43 | limactl shell ctf sudo /tmp/emperium 44 | 45 | In another terminal connect with 46 | ssh -F $HOME/.lima/ctf/ssh.config -L "*:8082:0.0.0.0:80" lima-ctf 47 | 48 | Start code-server with: 49 | PASSWORD=password code-server --bind-addr=0.0.0.0 > /tmp/code.log & 50 | ------ 51 | -------------------------------------------------------------------------------- /eBPF/map/go.mod: -------------------------------------------------------------------------------- 1 | module github.com/thebsdbox/eBPF-Summit-2024-CTF/eBPF/map 2 | 3 | go 1.21.3 4 | 5 | require github.com/cilium/ebpf v0.16.0 6 | 7 | require ( 8 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 // indirect 9 | golang.org/x/sys v0.20.0 // indirect 10 | ) 11 | -------------------------------------------------------------------------------- /eBPF/map/go.sum: -------------------------------------------------------------------------------- 1 | github.com/cilium/ebpf v0.16.0 h1:+BiEnHL6Z7lXnlGUsXQPPAE7+kenAd4ES8MQ5min0Ok= 2 | github.com/cilium/ebpf v0.16.0/go.mod h1:L7u2Blt2jMM/vLAVgjxluxtBKlz3/GWjB0dMOEngfwE= 3 | github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI= 4 | github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow= 5 | github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI= 6 | github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY= 7 | github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE= 8 | github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk= 9 | github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY= 10 | github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE= 11 | github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M= 12 | github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA= 13 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 h1:Jvc7gsqn21cJHCmAWx0LiimpP18LZmUxkT5Mp7EZ1mI= 14 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc= 15 | golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y= 16 | golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA= 17 | -------------------------------------------------------------------------------- /eBPF/map/main.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | log "log/slog" 5 | 6 | "github.com/cilium/ebpf" 7 | "github.com/cilium/ebpf/rlimit" 8 | ) 9 | 10 | func main() { 11 | // Allow the current process to lock memory for eBPF resources. 12 | if err := rlimit.RemoveMemlock(); err != nil { 13 | log.Error("rlimit") 14 | panic(err) 15 | } 16 | // Create our templatae map spec 17 | mapSpec := ebpf.MapSpec{ 18 | Type: ebpf.Hash, 19 | KeySize: 1, // 4 bytes for u32 20 | ValueSize: 20, 21 | MaxEntries: 1, // We'll have 1 entry 22 | } 23 | 24 | // Lets create a map 25 | mapSpec.Name = "" 26 | mapSpec.Contents = []ebpf.MapKV{ 27 | {Key: uint8(1), Value: []byte("")}, 28 | } 29 | m, err := ebpf.NewMap(&mapSpec) 30 | if err != nil { 31 | log.Error("map create fail ") 32 | panic(err) 33 | } 34 | defer m.Close() 35 | //time.Sleep(time.Minute) 36 | } 37 | -------------------------------------------------------------------------------- /eBPF/redirect/ebpf/redirect.c: -------------------------------------------------------------------------------- 1 | // +build ignore 2 | 3 | #include "../../header/vmlinux.h" 4 | #include 5 | #include 6 | #include 7 | 8 | #pragma pack(1) 9 | // TC Return codes 10 | #define TC_ACT_OK 0 11 | #define TC_ACT_SHOT 2 12 | 13 | #define ETH_P_IP 0x0800 /* Internet Protocol packet */ 14 | #define ETH_HLEN 14 /*Ethernet Header Length */ 15 | #define ETH_ALEN 6 16 | 17 | char __license[] SEC("license") = "GPL"; 18 | 19 | static inline int redirect_tcp(struct __sk_buff *skb, bool ingress) { 20 | // Get pointers to the beginning and end 21 | void *data_end = (void *)(long)skb->data_end; 22 | void *data = (void *)(long)skb->data; 23 | 24 | // Point to ethernet header 25 | struct ethhdr *eth = data; 26 | __u16 h_proto; 27 | __u64 nh_off = 0; 28 | nh_off = sizeof(*eth); 29 | 30 | if (data + nh_off > data_end) { 31 | return TC_ACT_OK; 32 | } 33 | 34 | // Get protocol 35 | h_proto = eth->h_proto; 36 | 37 | // if it is IP continue 38 | if (h_proto == bpf_htons(ETH_P_IP)) { 39 | struct iphdr *iph = data + nh_off; 40 | 41 | // Get pointer to IP Header 42 | if ((void *)(iph + 1) > data_end) { 43 | return TC_ACT_OK; 44 | } 45 | 46 | // Check protocol inside IP packet 47 | if (iph->protocol != IPPROTO_TCP) { 48 | return TC_ACT_OK; 49 | } 50 | __u32 ip_hlen = 0; 51 | 52 | ip_hlen = iph->ihl << 2; 53 | 54 | if (ip_hlen < sizeof(*iph)) { 55 | return TC_ACT_OK; 56 | } 57 | struct iphdr ip; 58 | struct tcphdr tcp; 59 | 60 | if (0 != bpf_skb_load_bytes(skb, sizeof(struct ethhdr), &ip, 61 | sizeof(struct iphdr))) { 62 | bpf_printk("bpf_skb_load_bytes iph failed"); 63 | return TC_ACT_OK; 64 | } 65 | 66 | if (0 != bpf_skb_load_bytes(skb, sizeof(struct ethhdr) + (ip.ihl << 2), 67 | &tcp, sizeof(struct tcphdr))) { 68 | bpf_printk("bpf_skb_load_bytes eth failed"); 69 | return TC_ACT_OK; 70 | } 71 | 72 | // something doesn't seem right here 73 | __u16 source = tcp.source; 74 | __u16 dest = tcp.dest; 75 | 76 | // Print out any traffic we might be interested in 77 | if (source > 1024 && dest > 1024) { 78 | bpf_printk("ingress:%s source: %d -> destination %d", 79 | ingress ? "true" : "false", source, dest); 80 | } 81 | 82 | if (ingress) { 83 | if (dest == 2001) { 84 | tcp.dest = 2000; 85 | long ret = 86 | bpf_skb_store_bytes(skb, sizeof(struct ethhdr) + (ip.ihl << 2), 87 | &tcp, sizeof(tcp), BPF_F_RECOMPUTE_CSUM); 88 | if (ret != 0) { 89 | bpf_printk("Error writing bytes"); 90 | } 91 | } 92 | } else { 93 | // something is missing here 94 | } 95 | 96 | // The Rebel engineer left some TCP dump output, might help, might be a read 97 | // herring 98 | /* 99 | 15:27:27.195146 IP (tos 0x0, ttl 64, id 64035, offset 0, flags [DF], proto 100 | TCP (6), length 60) 127.0.0.1.55590 > 127.0.0.1.2001: Flags [S], cksum 101 | 0xfe30 (incorrect -> 0xde8f), seq 1127217463, win 65495, options [mss 102 | 65495,sackOK,TS val 1342243858 ecr 0,nop,wscale 7], length 0 15:27:27.195160 103 | IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 40) 104 | 127.0.0.1.2001 > 127.0.0.1.55590: Flags [R.], cksum 0x946e (correct), seq 0, 105 | ack 1127217464, win 0, length 0 106 | 107 | 15:27:19.192319 IP (tos 0x0, ttl 64, id 57861, offset 0, flags [DF], 108 | proto TCP (6), length 60) 127.0.0.1.50720 > 127.0.0.1.2001: Flags [S], cksum 109 | 0xfe30 (incorrect -> 0xb3db), seq 1553087697, win 65495, options [mss 110 | 65495,sackOK,TS val 1342235856 ecr 0,nop,wscale 7], length 0 15:27:19.192345 111 | IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 60) 112 | 127.0.0.1.2000 > 127.0.0.1.50720: Flags [S.], cksum 0xfe30 (incorrect -> 113 | 0x7bf5), seq 2242477415, ack 1553087698, win 65483, options [mss 114 | 65495,sackOK,TS val 1342235856 ecr 1342235856,nop,wscale 7], length 0 115 | 15:27:19.192359 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP 116 | (6), length 40) 127.0.0.1.50720 > 127.0.0.1.2001: Flags [R], cksum 0x4a89 117 | (incorrect -> 0x4a88), seq 1553087698, win 0, length 0 118 | */ 119 | return TC_ACT_OK; 120 | } 121 | return TC_ACT_OK; 122 | } 123 | // eBPF hooks - This is where the magic happens! 124 | SEC("tc_in") 125 | int tc_ingress(struct __sk_buff *skb) { return redirect_tcp(skb, true); } 126 | 127 | SEC("tc_egress") 128 | int tc_egress_(struct __sk_buff *skb) { return redirect_tcp(skb, false); } 129 | -------------------------------------------------------------------------------- /eBPF/redirect/go.mod: -------------------------------------------------------------------------------- 1 | module github.com/thebsdbox/emperium/eBPF/redirect 2 | 3 | go 1.21.3 4 | 5 | require ( 6 | github.com/cilium/ebpf v0.16.0 7 | github.com/sirupsen/logrus v1.9.3 8 | github.com/vishvananda/netlink v1.3.0 9 | golang.org/x/sys v0.24.0 10 | ) 11 | 12 | require ( 13 | github.com/vishvananda/netns v0.0.4 // indirect 14 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 // indirect 15 | ) 16 | -------------------------------------------------------------------------------- /eBPF/redirect/go.sum: -------------------------------------------------------------------------------- 1 | github.com/cilium/ebpf v0.16.0 h1:+BiEnHL6Z7lXnlGUsXQPPAE7+kenAd4ES8MQ5min0Ok= 2 | github.com/cilium/ebpf v0.16.0/go.mod h1:L7u2Blt2jMM/vLAVgjxluxtBKlz3/GWjB0dMOEngfwE= 3 | github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 4 | github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c= 5 | github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 6 | github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI= 7 | github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow= 8 | github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI= 9 | github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY= 10 | github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE= 11 | github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk= 12 | github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY= 13 | github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE= 14 | github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM= 15 | github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4= 16 | github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDNXVBh4M= 17 | github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA= 18 | github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ= 19 | github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ= 20 | github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME= 21 | github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY= 22 | github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg= 23 | github.com/vishvananda/netlink v1.3.0 h1:X7l42GfcV4S6E4vHTsw48qbrV+9PVojNfIhZcwQdrZk= 24 | github.com/vishvananda/netlink v1.3.0/go.mod h1:i6NetklAujEcC6fK0JPjT8qSwWyO0HLn4UKG+hGqeJs= 25 | github.com/vishvananda/netns v0.0.4 h1:Oeaw1EM2JMxD51g9uhtC0D7erkIjgmj8+JZc26m1YX8= 26 | github.com/vishvananda/netns v0.0.4/go.mod h1:SpkAiCQRtJ6TvvxPnOSyH3BMl6unz3xZlaprSwhNNJM= 27 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 h1:Jvc7gsqn21cJHCmAWx0LiimpP18LZmUxkT5Mp7EZ1mI= 28 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc= 29 | golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= 30 | golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= 31 | golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= 32 | golang.org/x/sys v0.24.0 h1:Twjiwq9dn6R1fQcyiK+wQyHWfaz/BJB+YIpzU/Cv3Xg= 33 | golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA= 34 | gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0= 35 | gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo= 36 | gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM= 37 | -------------------------------------------------------------------------------- /eBPF/redirect/main.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "bufio" 5 | "context" 6 | "errors" 7 | "flag" 8 | "fmt" 9 | "io" 10 | "net" 11 | "os" 12 | "os/signal" 13 | "syscall" 14 | 15 | log "github.com/sirupsen/logrus" 16 | "github.com/vishvananda/netlink" 17 | "golang.org/x/sys/unix" 18 | 19 | "github.com/cilium/ebpf" 20 | ) 21 | 22 | //go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc clang -cflags "-O2 -g -Wall -Werror" redirect ./ebpf/redirect.c -- -I../../headers 23 | 24 | func main() { 25 | 26 | ifaceName := flag.String("interface", "lo", "The interface to watch network traffic on") 27 | 28 | flag.Parse() 29 | 30 | log.Info("Starting 🐝 the eBPF redirecter, on interface [%s]", *ifaceName) 31 | 32 | ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM) 33 | defer stop() 34 | // Look up the network interface by name. 35 | devID, err := net.InterfaceByName(*ifaceName) 36 | if err != nil { 37 | panic(fmt.Sprintf("lookup network iface %s: %s", *ifaceName, err)) 38 | } 39 | 40 | objs := redirectObjects{} 41 | 42 | if err := loadRedirectObjects(&objs, nil); err != nil { 43 | var verr *ebpf.VerifierError 44 | if errors.As(err, &verr) { 45 | fmt.Printf("%+v\n", verr) 46 | } 47 | log.Fatalf("loading objects: %s", err) 48 | } 49 | defer objs.Close() 50 | 51 | qdisc := &netlink.GenericQdisc{ 52 | QdiscAttrs: netlink.QdiscAttrs{ 53 | LinkIndex: devID.Index, 54 | Handle: netlink.MakeHandle(0xffff, 0), 55 | Parent: netlink.HANDLE_INGRESS, 56 | }, 57 | QdiscType: "clsact", 58 | } 59 | 60 | err = netlink.QdiscReplace(qdisc) 61 | if err != nil { 62 | log.Fatalf("could not get replace qdisc: %v", err) 63 | } 64 | log.Info("Loaded TC QDisc") 65 | 66 | filterIngress := &netlink.BpfFilter{ 67 | FilterAttrs: netlink.FilterAttrs{ 68 | LinkIndex: devID.Index, 69 | Parent: netlink.HANDLE_MIN_INGRESS, 70 | Handle: 1, 71 | Protocol: unix.ETH_P_ALL, 72 | }, 73 | Fd: objs.TcIngress.FD(), 74 | Name: objs.TcIngress.String(), 75 | DirectAction: true, 76 | } 77 | 78 | if err := netlink.FilterReplace(filterIngress); err != nil { 79 | log.Fatalf("failed to replace tc filter: %v", err) 80 | } 81 | 82 | filterEgress := &netlink.BpfFilter{ 83 | FilterAttrs: netlink.FilterAttrs{ 84 | LinkIndex: devID.Index, 85 | Parent: netlink.HANDLE_MIN_EGRESS, 86 | Handle: 1, 87 | Protocol: unix.ETH_P_ALL, 88 | }, 89 | Fd: objs.TcEgress.FD(), 90 | Name: objs.TcEgress.String(), 91 | DirectAction: true, 92 | } 93 | 94 | if err := netlink.FilterReplace(filterEgress); err != nil { 95 | log.Fatalf("failed to replace tc filter: %v", err) 96 | } 97 | 98 | log.Printf("Press Ctrl-C to exit and remove the program") 99 | 100 | // Drop the logs 101 | go cat() 102 | <-ctx.Done() // We wait here 103 | 104 | log.Info("Removing eBPF programs") 105 | 106 | link, err := netlink.LinkByName(*ifaceName) 107 | if err != nil { 108 | log.Fatalf("could not find iface: %v", err) 109 | } 110 | 111 | f, err := netlink.FilterList(link, netlink.HANDLE_MIN_INGRESS) 112 | if err != nil { 113 | log.Fatalf("could not list filters: %v", err) 114 | } 115 | 116 | if len(f) == 0 { 117 | log.Error("Unable to clean any filters") 118 | } 119 | for x := range f { 120 | err = netlink.FilterDel(f[x]) 121 | if err != nil { 122 | log.Fatalf("could not get remove filter: %v", err) 123 | } 124 | } 125 | 126 | f, err = netlink.FilterList(link, netlink.HANDLE_MIN_EGRESS) 127 | if err != nil { 128 | log.Fatalf("could not list filters: %v", err) 129 | } 130 | 131 | if len(f) == 0 { 132 | log.Error("Unable to clean any filters") 133 | } 134 | for x := range f { 135 | err = netlink.FilterDel(f[x]) 136 | if err != nil { 137 | log.Fatalf("could not get remove filter: %v", err) 138 | } 139 | } 140 | } 141 | func readLines(r io.Reader) { 142 | rd := bufio.NewReader(r) 143 | for { 144 | line, err := rd.ReadString('\n') 145 | if err == io.EOF { 146 | break 147 | } 148 | if err != nil { 149 | log.Fatal(err) 150 | } 151 | 152 | fmt.Printf("%s", line) 153 | 154 | } 155 | } 156 | 157 | func cat() { 158 | file, err := os.Open("/sys/kernel/tracing/trace_pipe") 159 | if err != nil { 160 | log.Fatal(err) 161 | } 162 | defer file.Close() 163 | readLines(file) 164 | } 165 | -------------------------------------------------------------------------------- /eBPF/response/ebpf/response.c: -------------------------------------------------------------------------------- 1 | // +build ignore 2 | 3 | #include "../../header/vmlinux.h" 4 | #include 5 | #include 6 | #include 7 | 8 | #pragma pack(1) 9 | 10 | char __license[] SEC("license") = "GPL"; 11 | 12 | // TC Return codes 13 | #define TC_ACT_OK 0 14 | #define TC_ACT_SHOT 2 15 | 16 | #define ETH_P_IP 0x0800 /* Internet Protocol packet */ 17 | #define ETH_HLEN 14 /*Ethernet Header Length */ 18 | #define ETH_ALEN 6 19 | 20 | #define IP_SRC_OFF (ETH_HLEN + offsetof(struct iphdr, saddr)) 21 | #define IP_DST_OFF (ETH_HLEN + offsetof(struct iphdr, daddr)) 22 | 23 | static inline int swap_udp(struct __sk_buff *skb) { 24 | // Get pointers to the beginning and end 25 | void *data_end = (void *)(long)skb->data_end; 26 | void *data = (void *)(long)skb->data; 27 | 28 | // Point to ethernet header 29 | struct ethhdr *eth = data; 30 | __u16 h_proto; 31 | __u64 nh_off = 0; 32 | nh_off = sizeof(*eth); 33 | 34 | if (data + nh_off > data_end) { 35 | return TC_ACT_OK; 36 | } 37 | 38 | // Get protocol 39 | h_proto = eth->h_proto; 40 | 41 | // if it is IP continue 42 | if (h_proto == bpf_htons(ETH_P_IP)) { 43 | struct iphdr *iph = data + nh_off; 44 | 45 | // Get pointer to IP Header 46 | if ((void *)(iph + 1) > data_end) { 47 | return TC_ACT_OK; 48 | } 49 | 50 | // Check protocol inside IP packet 51 | if (iph->protocol != IPPROTO_UDP) { 52 | return TC_ACT_OK; 53 | } 54 | __u32 ip_hlen = 0; 55 | //__u32 poffset = 0; 56 | //__u32 plength = 0; 57 | // __u32 ip_total_length = bpf_ntohs(iph->tot_len); 58 | 59 | ip_hlen = iph->ihl << 2; 60 | 61 | if (ip_hlen < sizeof(*iph)) { 62 | return TC_ACT_OK; 63 | } 64 | struct udphdr *udph = data + nh_off + sizeof(*iph); 65 | 66 | if ((void *)(udph + 1) > data_end) { 67 | return TC_ACT_OK; 68 | } 69 | __u16 src_port = bpf_ntohs(udph->source); 70 | __u16 dst_port = bpf_ntohs(udph->dest); 71 | 72 | // Is the destination port the correct one? 73 | if (dst_port == 9000) { 74 | bpf_printk("UDP %d %d", src_port, dst_port); 75 | 76 | u32 payload_offset = sizeof(*eth) + sizeof(*iph) + sizeof(*udph); 77 | u32 payload_length = iph->tot_len - (sizeof(*iph) + sizeof(*udph)); 78 | 79 | if (payload_length < 3) { 80 | return TC_ACT_OK; 81 | } 82 | 83 | uint8_t data[4]; 84 | u32 ret = bpf_skb_load_bytes(skb, payload_offset, data, sizeof(data) - 1); 85 | if (ret) { 86 | bpf_printk("error"); 87 | return TC_ACT_OK; 88 | } 89 | data[3] = '\0'; // null terminate the string 90 | bpf_printk("data: %s", data); 91 | 92 | u32 data_offset = sizeof(*eth) + sizeof(*iph) + sizeof(*udph); 93 | 94 | data[0] = '?'; 95 | 96 | ret = bpf_skb_store_bytes(skb, data_offset, &data, sizeof(data), 97 | BPF_F_RECOMPUTE_CSUM); 98 | 99 | // Something doesn't seem right 100 | 101 | /* We'll store the mac addresses (L2) */ 102 | __u8 src_mac[ETH_ALEN]; 103 | __u8 dst_mac[ETH_ALEN]; 104 | __builtin_memcpy(src_mac, eth->h_source, ETH_ALEN); 105 | __builtin_memcpy(dst_mac, eth->h_dest, ETH_ALEN); 106 | 107 | /* ip addresses (L3) */ 108 | __be32 src_ip = iph->saddr; 109 | __be32 dst_ip = iph->daddr; 110 | 111 | /* and source/destination ports (L4) */ 112 | __be16 dest_port = udph->dest; 113 | __be16 src_port = udph->source; 114 | 115 | /* and then swap them all */ 116 | 117 | /* Swap the mac addresses */ 118 | bpf_skb_store_bytes(skb, offsetof(struct ethhdr, h_source), dst_mac, 119 | ETH_ALEN, 0); 120 | bpf_skb_store_bytes(skb, offsetof(struct ethhdr, h_dest), src_mac, 121 | ETH_ALEN, 0); 122 | 123 | /* Swap the ip addresses 124 | * swapping the ips does not require checksum recalculation, 125 | * but we might want to reduce the TTL to prevent packets infinitely 126 | * looping between us and another device that does not reduce the TTL */ 127 | bpf_skb_store_bytes(skb, 128 | sizeof(struct ethhdr) + offsetof(struct iphdr, saddr), 129 | &dst_ip, sizeof(dst_ip), 0); 130 | bpf_skb_store_bytes(skb, 131 | sizeof(struct ethhdr) + offsetof(struct iphdr, daddr), 132 | &src_ip, sizeof(src_ip), 0); 133 | 134 | /* Swap the source and destination ports in the udp packet */ 135 | bpf_skb_store_bytes(skb, 136 | sizeof(struct ethhdr) + sizeof(struct iphdr) + 137 | offsetof(struct udphdr, source), 138 | &dest_port, sizeof(dest_port), 0); 139 | bpf_skb_store_bytes(skb, 140 | sizeof(struct ethhdr) + sizeof(struct iphdr) + 141 | offsetof(struct udphdr, dest), 142 | &src_port, sizeof(src_port), 0); 143 | 144 | /* And then send it back from wherever it's come from */ 145 | ret = bpf_clone_redirect(skb, skb->ifindex, 0); 146 | if (ret) { 147 | bpf_printk("bpf_clone_redirect error: %d", ret); 148 | } 149 | /* Since we've handled the packet, drop it */ 150 | return TC_ACT_SHOT; 151 | } 152 | 153 | return TC_ACT_OK; 154 | } 155 | return TC_ACT_OK; 156 | } 157 | 158 | // eBPF hooks - This is where the magic happens! 159 | SEC("tc_in") 160 | int tc_ingress(struct __sk_buff *skb) { return swap_udp(skb); } 161 | 162 | SEC("tc_egress") 163 | int tc_egress_(struct __sk_buff *skb) { return swap_udp(skb); } 164 | -------------------------------------------------------------------------------- /eBPF/response/go.mod: -------------------------------------------------------------------------------- 1 | module github.com/thebsdbox/eBPF-Summit-2024-CTF/eBPF/response 2 | 3 | go 1.21.3 4 | 5 | require ( 6 | github.com/praserx/ipconv v1.2.2 7 | github.com/sirupsen/logrus v1.9.3 8 | github.com/vishvananda/netlink v1.1.0 9 | golang.org/x/sys v0.24.0 10 | ) 11 | 12 | require ( 13 | github.com/cilium/ebpf v0.16.0 // indirect 14 | github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect 15 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 // indirect 16 | ) 17 | -------------------------------------------------------------------------------- /eBPF/response/go.sum: -------------------------------------------------------------------------------- 1 | github.com/cilium/ebpf v0.16.0 h1:+BiEnHL6Z7lXnlGUsXQPPAE7+kenAd4ES8MQ5min0Ok= 2 | github.com/cilium/ebpf v0.16.0/go.mod h1:L7u2Blt2jMM/vLAVgjxluxtBKlz3/GWjB0dMOEngfwE= 3 | github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 4 | github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c= 5 | github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 6 | github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM= 7 | github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4= 8 | github.com/praserx/ipconv v1.2.2 h1:oz4XXNjywgoJRAnSymUET03OwSLL7JDVjQQEtl08XV8= 9 | github.com/praserx/ipconv v1.2.2/go.mod h1:DSy+AKre/e3w/npsmUDMio+OR/a2rvmMdI7rerOIgqI= 10 | github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ= 11 | github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ= 12 | github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME= 13 | github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY= 14 | github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg= 15 | github.com/vishvananda/netlink v1.1.0 h1:1iyaYNBLmP6L0220aDnYQpo1QEV4t4hJ+xEEhhJH8j0= 16 | github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE= 17 | github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df h1:OviZH7qLw/7ZovXvuNyL3XQl8UFofeikI1NW1Gypu7k= 18 | github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df/go.mod h1:JP3t17pCcGlemwknint6hfoeCVQrEMVwxRLRjXpq+BU= 19 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2 h1:Jvc7gsqn21cJHCmAWx0LiimpP18LZmUxkT5Mp7EZ1mI= 20 | golang.org/x/exp v0.0.0-20230224173230-c95f2b4c22f2/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc= 21 | golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs= 22 | golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= 23 | golang.org/x/sys v0.24.0 h1:Twjiwq9dn6R1fQcyiK+wQyHWfaz/BJB+YIpzU/Cv3Xg= 24 | golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA= 25 | gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0= 26 | gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo= 27 | gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM= 28 | -------------------------------------------------------------------------------- /eBPF/response/main.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "bufio" 5 | "context" 6 | "errors" 7 | "flag" 8 | "fmt" 9 | "io" 10 | "net" 11 | "os" 12 | "os/signal" 13 | "syscall" 14 | 15 | "github.com/cilium/ebpf" 16 | log "github.com/sirupsen/logrus" 17 | "github.com/vishvananda/netlink" 18 | "golang.org/x/sys/unix" 19 | ) 20 | 21 | //go:generate go run github.com/cilium/ebpf/cmd/bpf2go -cc clang -cflags "-O2 -g -Wall -Werror" udp ./ebpf/response.c -- -I../../headers 22 | 23 | func main() { 24 | 25 | ifaceName := flag.String("interface", "lo", "The interface to watch network traffic on") 26 | flag.Parse() 27 | 28 | log.Infof("Starting 🐝 the eBPF UDP watcher, on interface [%s]", *ifaceName) 29 | 30 | ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM) 31 | defer stop() 32 | // Look up the network interface by name. 33 | devID, err := net.InterfaceByName(*ifaceName) 34 | if err != nil { 35 | log.Fatalf("lookup network iface %s: %s", *ifaceName, err) 36 | } 37 | 38 | // Load pre-compiled programs into the kernel. 39 | objs := udpObjects{} 40 | if err := loadUdpObjects(&objs, nil); err != nil { 41 | var verr *ebpf.VerifierError 42 | if errors.As(err, &verr) { 43 | fmt.Printf("%+v\n", verr) 44 | } 45 | log.Fatalf("loading objects: %s", err) 46 | } 47 | 48 | defer objs.Close() 49 | qdisc := &netlink.GenericQdisc{ 50 | QdiscAttrs: netlink.QdiscAttrs{ 51 | LinkIndex: devID.Index, 52 | Handle: netlink.MakeHandle(0xffff, 0), 53 | Parent: netlink.HANDLE_INGRESS, 54 | }, 55 | QdiscType: "clsact", 56 | } 57 | 58 | err = netlink.QdiscReplace(qdisc) 59 | if err != nil { 60 | log.Fatalf("could not get replace qdisc: %v", err) 61 | } 62 | log.Info("Loaded TC QDisc") 63 | 64 | filterIngress := &netlink.BpfFilter{ 65 | FilterAttrs: netlink.FilterAttrs{ 66 | LinkIndex: devID.Index, 67 | Parent: netlink.HANDLE_MIN_INGRESS, 68 | Handle: 1, 69 | Protocol: unix.ETH_P_ALL, 70 | }, 71 | Fd: objs.TcIngress.FD(), 72 | Name: objs.TcIngress.String(), 73 | DirectAction: true, 74 | } 75 | 76 | if err := netlink.FilterReplace(filterIngress); err != nil { 77 | log.Fatalf("failed to replace tc filter: %v", err) 78 | } 79 | 80 | filterEgress := &netlink.BpfFilter{ 81 | FilterAttrs: netlink.FilterAttrs{ 82 | LinkIndex: devID.Index, 83 | Parent: netlink.HANDLE_MIN_EGRESS, 84 | Handle: 1, 85 | Protocol: unix.ETH_P_ALL, 86 | }, 87 | Fd: objs.TcEgress.FD(), 88 | Name: objs.TcEgress.String(), 89 | DirectAction: true, 90 | } 91 | 92 | if err := netlink.FilterReplace(filterEgress); err != nil { 93 | log.Fatalf("failed to replace tc filter: %v", err) 94 | } 95 | 96 | log.Printf("Press Ctrl-C to exit and remove the program") 97 | 98 | // Drop the logs 99 | go cat() 100 | <-ctx.Done() // We wait here 101 | log.Info("Removing eBPF programs") 102 | 103 | link, err := netlink.LinkByName(*ifaceName) 104 | if err != nil { 105 | log.Fatalf("could not find iface: %v", err) 106 | } 107 | 108 | f, err := netlink.FilterList(link, netlink.HANDLE_MIN_INGRESS) 109 | if err != nil { 110 | log.Fatalf("could not list filters: %v", err) 111 | } 112 | 113 | if len(f) == 0 { 114 | log.Error("Unable to clean any filters") 115 | } 116 | for x := range f { 117 | err = netlink.FilterDel(f[x]) 118 | if err != nil { 119 | log.Fatalf("could not get remove filter: %v", err) 120 | } 121 | } 122 | 123 | f, err = netlink.FilterList(link, netlink.HANDLE_MIN_EGRESS) 124 | if err != nil { 125 | log.Fatalf("could not list filters: %v", err) 126 | } 127 | 128 | if len(f) == 0 { 129 | log.Error("Unable to clean any filters") 130 | } 131 | for x := range f { 132 | err = netlink.FilterDel(f[x]) 133 | if err != nil { 134 | log.Fatalf("could not get remove filter: %v", err) 135 | } 136 | } 137 | } 138 | 139 | func readLines(r io.Reader) { 140 | rd := bufio.NewReader(r) 141 | for { 142 | line, err := rd.ReadString('\n') 143 | if err == io.EOF { 144 | break 145 | } 146 | if err != nil { 147 | log.Fatal(err) 148 | } 149 | 150 | fmt.Printf("%s", line) 151 | 152 | } 153 | } 154 | 155 | func cat() { 156 | file, err := os.Open("/sys/kernel/tracing/trace_pipe") 157 | if err != nil { 158 | log.Fatal(err) 159 | } 160 | defer file.Close() 161 | readLines(file) 162 | } 163 | --------------------------------------------------------------------------------