eBPF Program Types

Inspektor Gadget automatically loads and attaches the eBPF programs contained in a gadget. This document describes the different types that are supported and specific details about them. The section name specifies the type of the program and the target they should be attached to.

Kprobes / Kretprobes

The section name must use the kprobe/<function_name> or kretprobe/<function_name> formats. <function_name> is the kernel function that the kprobe will be attached to.

Tracepoints

The section name must use the tracepoint/<tracepoint_name>. <tracepoint_name> is one of the available tracepoints on /sys/kernel/debug/tracing/events.

Socket Filter

The section name must start with socket. Socket programs are attached to all network namespaces matching the filter configuration when running the gadget.

Tracing

Currently we support some iterators and fentry/fexit programs.

Iterators

The section name must use iter/<iter_type>. <iter_type> is one of task, tcp or udp. tcp and udp iterators are invoked in different network namespaces matching the filter configuration when running the gadget.

Fentry / Fexit

The section name must use the fentry/<function_name or fexit/<function_name>. As in kprobes, <function_name> is the kernel function that the kprobe will be attached to.

Raw Tracepoints

TODO!

SchedCLS

The section name must use the classifier/<ingress|egress>/<program_name> format. SchedCLS programs are attached to the peer of the networking interface of the containers on the host according to the filtering configuration.

Inspektor Gadget supports running multiple gadgets that use SchedCLS programs at the same time. Programs must return TC_ACT_UNSPEC in order to allow the packet to be processed by other gadgets. The order of execution of the programs is not deterministic, this is something we could visit later on.

Uprobes / Uretprobes

The section name must use the <prog_type>/<file_path>:<symbol> format. <prog_type> must be either uprobe or uretprobe. <file_path> is the absolute path of an executable or a library, that the uprobe will be attached to. For common libraries, <file_path> can also be the library’s name, such as libc. <symbol> is a debugging symbol that can be found in the file mentioned above.

User-Level Statically Defined Tracing (USDT)

The section name must use the usdt/<file_path>:<providerName>:<probeName> format. <file_path> can be either an absolute path or a library name, same as the field in Uprobe. <providerName> and <probeName> are two fields that can jointly identify a USDT trace point.