PREVAIL - A new eBPF verifier

a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer

The version discussed in the PLDI paper is available here.

Getting Started

Clone:

git clone --recurse-submodules https://github.com/vbpf/ebpf-verifier.git
cd ebpf-verifier

Building

🐧 Linux

Dependencies (Ubuntu)

sudo apt install build-essential git cmake libboost-dev libyaml-cpp-dev
sudo apt install libboost-filesystem-dev libboost-program-options-dev

Make

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

🪟 Windows

Dependencies

• Install git
• Install Visual Studio Build Tools 2022 and choose the "C++ build tools" workload (Visual Studio Build Tools 2022 has support for CMake Version 3.25).
• Install nuget.exe

Make on Windows (which uses a multi-configuration generator)

cmake -B build
cmake --build build --config Release

🍏 macOS

Dependencies:

brew install llvm cmake boost yaml-cpp

The system llvm currently comes with Clang 15, which isn't enough to compile the ebpf-verifier, as it depends on C++20. Brew's llvm comes with Clang 17.

Make:

export CPATH=$(brew --prefix)/include LIBRARY_PATH=$(brew --prefix)/lib CMAKE_PREFIX_PATH=$(brew --prefix)
cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=$(brew --prefix llvm)/bin/clang -DCMAKE_CXX_COMPILER=$(brew --prefix llvm)/bin/clang++
cmake --build build

🐋 Docker

Build and run

docker build -t verifier .
docker run -it verifier ebpf-samples/cilium/bpf_lxc.o 2/1
1,0.009812,4132
# To run the Linux verifier you'll need a privileged container:
docker run --privileged -it verifier ebpf-samples/linux/cpustat_kern.o --domain=linux

Example:

ebpf-verifier$ ./check ebpf-samples/cilium/bpf_lxc.o 2/1
1,0.008288,4064

The output is three comma-separated values:

• 1 or 0, for "pass" and "fail" respectively
• The runtime of the fixpoint algorithm (in seconds)
• The peak memory consumption, in kb, as reflected by the resident-set size (rss)

Usage

PREVAIL is a new eBPF verifier based on abstract interpretation.
Usage: ./check [OPTIONS] path [section] [function]

Positionals:
  path TEXT:FILE REQUIRED     Elf file to analyze
  section SECTION             Section to analyze
  function FUNCTION           Function to analyze

Options:
  -h,--help                   Print this help message and exit
  --section SECTION           Section to analyze
  --function FUNCTION         Function to analyze
  -l                          List programs
  --domain DOMAIN:{stats,linux,zoneCrab,cfg} [zoneCrab]
                              Abstract domain


Features:
  --termination,--no-verify-termination{false}
                              Verify termination. Default: ignore
  --allow-division-by-zero,--no-division-by-zero{false}
                              Handling potential division by zero. Default: allow
  -s,--strict                 Apply additional checks that would cause runtime failures
  --include_groups GROUPS:{atomic32,atomic64,base32,base64,callx,divmul32,divmul64,packet}
                              Include conformance groups
  --exclude_groups GROUPS:{atomic32,atomic64,base32,base64,callx,divmul32,divmul64,packet}
                              Exclude conformance groups


Verbosity:
  --simplify,--no-simplify{false}
                              Simplify the CFG before analysis by merging chains of instructions into a single basic block. Default: enabled
  --line-info                 Print line information
  --print-btf-types           Print BTF types
  --assume-assert,--no-assume-assert{false}
                              Assume assertions (useful for debugging verification failures). Default: disabled
  -i                          Print invariants
  -f                          Print verifier's failure logs
  -v                          Print both invariants and failures


CFG output:
  --asm FILE                  Print disassembly to FILE
  --dot FILE                  Export control-flow graph to dot FILE

A standard alternative to the --asm flag is llvm-objdump -S FILE.

The cfg can be viewed using dot and the standard PDF viewer:

sudo apt install graphviz
./check ebpf-samples/cilium/bpf_lxc.o 2/1 --dot cfg.dot --domain=stats
dot -Tpdf cfg.dot > cfg.pdf

Testing the Linux verifier

To run the Linux verifier, you must use sudo:

sudo ./check ebpf-samples/linux/cpustat_kern.o tracepoint/power/cpu_idle --domain=linux