10 Developer Challenges Related to eBPF

​eBPF (extended Berkeley Packet Filter) is a technology that allows for safe and efficient execution of programs in the Linux kernel without changing kernel source code or loading kernel modules. ​The following 10 developer challenges related to the deployment and use of eBPF (extended Berkeley Packet Filter) were derived from the analysis of the 702 eBPF-related questions asked on the StackOverflow support forum. You can view these questions here. 

1. Connecting Programs to Attach Points: Developer challenges related to attaching eBPF programs to the various types of Linux kernel hooks, such as socket filters, XDP (eXpress Data Path) programs, TC (Traffic Control) actions, and kprobes/uprobes for tracing kernel or user-space functions.
   eBPF programs can be attached to various Linux kernel hooks including:
   1. Tracepoints: These are static hooks placed in strategic parts of the kernel code by the kernel developers. They provide a stable API for eBPF programs to probe.
   2. Kprobes: Dynamic tracing hooks that can be placed almost anywhere in the kernel code. They allow an eBPF program to access almost any function within the kernel.
   3. Uprobes: Similar to Kprobes but placed in user-space applications. They allow eBPF programs to trace any function in a user-space application.
   4. Sockets: eBPF programs can be attached to sockets to monitor and manipulate network traffic.
   5. Network devices: eBPF programs can be attached at various points in the networking stack, such as Traffic Control (TC) or XDP (eXpress Data Path), to process packets.
   6. Perf events: These are hooks triggered by hardware or software performance events, such as CPU cycles or cache misses.
   7. Cgroup events: eBPF programs can be attached to control groups (cgroups) to monitor and enforce resource limits.
   8. Syscalls: eBPF programs can be attached to syscalls to monitor and control interactions between user-space and the kernel.
   9. Sched events: These are hooks related to the scheduler, allowing eBPF programs to trace task switches, forks, or process exits.
2. eBPF Maps: Challenges related to the usage and management of eBPF maps, which are data structures used to store and share data between eBPF programs and user space. This includes topics on map creation, updating, deletion, and accessing map elements. Concerns about map sharing between different eBPF programs, concurrent modifications, and related errors are also surfaced.
   Use Case: eBPF Maps can indeed help in connecting network traffic patterns to specific applications for improved observability. By using eBPF Maps, an eBPF program can track the process ID (PID) associated with each network connection and store this information. A user-space program can then access this map to correlate network activity with specific applications, thereby enhancing system observability.
3. Helpers and Operations: Developers discuss the use of eBPF helper functions, which are pre-defined functions provided by the Linux kernel that eBPF programs can call. Topics cover helpers used for various tasks such as loading bytes from packets, performing checksum calculations, adjusting packet headers, and managing maps.
   Example Challenge: eBPF helper functions can be used for network monitoring and troubleshooting. For example, a helper function can load bytes from packets to analyze network traffic and identify anomalies or perform checksum calculations to ensure data integrity during the transport process.
4. eBPF Tools and Utilities: Issues related to the usage of tools and utilities like BCC (BPF Compiler Collection), libbpf, bpftool, and redbpf for developing, debugging, and managing eBPF programs. Issues related to installing tools, importing libraries, and troubleshooting errors during the build process of eBPF-related software are included.
   Example Challenge: A company is developing a new software application and wants to ensure that it's efficient and performs well. The development team decides to use eBPF tools and utilities such as BCC and libbpf to monitor the application's performance. However, they encounter issues while installing these tools and importing necessary libraries, creating a roadblock in their development process. They also face challenges during the build process of their eBPF-related software due to some errors. Using eBPF tools, they are able to identify the bottlenecks, debug the issues, and optimize the application's performance, leading to a smoother user experience and improved application efficiency.
5. Tracing and Debugging: Employing eBPF for function tracing to gather information about function calls, system calls, or other system events. Usage of kprobes, uprobes, and tracepoints, as well as debugging eBPF programs using different methods to understand and resolve errors.
   Example Challenge: A developer is using eBPF for function tracing in an effort to diagnose performance issues in a large-scale cloud computing environment. They have chosen to use kprobes and uprobes to gather information about specific function calls and system calls. However, they are facing a challenge in determining the appropriate locations to place these probes without disrupting system performance. Additionally, they are finding it difficult to interpret the large volume of data collected from these probes. Lastly, they are struggling to use tracepoints for more stable API probing, as the kernel version they are working on has limited tracepoints available. This scenario encapsulates the challenges related to the placement and effective use of kprobes, uprobes, and tracepoints in eBPF function tracing.
6. Performance and Optimization: Examining the performance implications of using eBPF in different scenarios, including packet processing, tracking file operations, and profiling. Topics also explore methods to ensure efficient eBPF program execution, such as using spinlocks, managing resource limits, and avoiding undefined behavior.Example Challenge: An organization is using eBPF for packet processing in their network monitoring system. They are trying to track file operations and profile system behavior to identify potential bottlenecks. However, they encounter performance issues due to the high volume of packets and system calls. They try to optimize their eBPF program by implementing spinlocks to handle synchronization and manage resource limits. But, avoiding undefined behavior in their eBPF programs becomes a challenge due to the complexity of their system and the lack of comprehensive debugging tools for eBPF. This scenario shows the difficulties in balancing performance and optimization while ensuring safe and correct behavior of eBPF programs.
7. Network Packet Processing: Modifying, redirecting, and filtering network packets through eBPF in various contexts, including XDP and TC. Challenges related to packet processing, like extracting packet data, modifying TCP/UDP ports, and computing checksums are covered.
   Example Challenge: A network engineer is using eBPF for real-time traffic management in a high-speed network environment. They are tasked with modifying and redirecting network packets at the XDP and TC levels for load balancing purposes. However, they are facing difficulties in extracting specific packet data due to the high-speed nature of the traffic. Additionally, they need to modify TCP/UDP ports on-the-fly to redirect the traffic, but the rapid pace and volume of the network traffic makes this task complex. Furthermore, they are required to compute checksums to detect errors in the transmitted data, but due to the high throughput of packets, this process is proving to be computationally intensive and challenging to manage in real time. This scenario represents the challenges associated with network packet processing using eBPF in a high-speed, high-volume network environment.
8. Security and Isolation: Utilizing eBPF for security purposes, like intercepting system calls with seccomp (secure computing mode) and maintaining isolation between processes or containers. The safety advantages of eBPF over traditional LKMs (Loadable Kernel Modules) are also addressed.
   Example Challenge: A security engineer is using eBPF to enhance the security of a system by intercepting system calls with seccomp. Their aim is to prevent certain types of system calls from reaching the kernel, thereby reducing the attack surface of their system. However, they are having difficulty configuring seccomp filters for complex applications with a wide array of system calls. Additionally, they want to maintain isolation between various processes and containers running on the system to prevent potential cross-contamination, but managing these rules across different environments is proving to be a challenge. Moreover, while eBPF provides safety advantages over traditional LKMs, understanding and leveraging these benefits requires a deep understanding of both technologies, adding another layer of complexity to their task.
9. Kernel Integration and Cgroup Usage: Insights into integrating eBPF programs with Linux kernel infrastructure, such as networking stack, block device layer, and cgroups. Discussions cover the interaction between eBPF programs and kernel structures or features, and the application of eBPF to tasks within specific kernel subsystems or namespaces.
   Example Challenge: A system administrator is using eBPF to monitor and control system resource usage within cgroups. They are trying to integrate eBPF programs with the Linux kernel infrastructure to track resource usage in different cgroups, enforcing limits and preventing resource hogging. However, they are encountering difficulties in ensuring reliable communication between eBPF programs and the kernel structures. They also struggle to apply eBPF effectively to tasks within specific kernel subsystems like the networking stack and block device layer. This task is further complicated by inconsistencies in kernel behavior across different Linux distributions. This scenario illustrates the challenges of kernel integration and cgroup usage in eBPF programming.
10. Error Handling and Verifier Messages: Diagnosing and resolving common errors that occur when developing eBPF programs, with a particular focus on issues related to the eBPF verifier, which ensures the safety and correctness of eBPF programs before they are executed in the kernel.
    Example Challenge: A developer is working on an eBPF program to monitor network traffic. As they test their program, they run into several errors flagged by the eBPF verifier. The verifier messages are complex and difficult to understand, making it challenging for the developer to pinpoint the exact issues in their eBPF code. Furthermore, they encounter a persistent issue where the verifier rejects their program due to an alleged infinite loop, though their review of the code doesn't reveal any such loop. This scenario represents the challenges of understanding and addressing verifier messages and handling errors when developing eBPF programs.
    Each of these subtopics encompasses specific challenges, error messages, coding questions, or situations encountered when working with eBPF technology, reflecting the breadth of applications and intricacies of developing eBPF-based solutions across different Linux kernel versions and environments.

Attach Points by Importance

The bars show the different eBPF attach points by frequency of discussion on StackOverflow.

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Challenge Types

The bars show the types of eBPF-related developer challenges based on their frequency on StackOverflow