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|
package tracepoints
import (
"fmt"
"maps"
"regexp"
"slices"
"strings"
)
// Selector holds compiled include and exclude regexes for choosing which
// tracepoints to attach at BPF probe registration time. It is the single
// authoritative home for tracepoint-selection logic, keeping that concern
// out of the top-level flags.Config.
type Selector struct {
// Attach is the list of compiled regexes that select which tracepoints to
// load. An empty list means "attach all non-excluded tracepoints".
Attach []*regexp.Regexp
// Exclude is the list of compiled regexes that suppress specific
// tracepoints even when they match the Attach list.
Exclude []*regexp.Regexp
// Syscalls optionally restricts attach to an explicit syscall allowlist.
// Keys are bare syscall names (for example "openat", not "sys_enter_openat").
// When RestrictSyscalls is true, only entries in this map are attached.
Syscalls map[string]struct{}
// RestrictSyscalls gates whether Syscalls should be enforced.
RestrictSyscalls bool
}
// ParseSelector parses the comma-separated regex strings for the -tps and
// -tpsExclude CLI flags into a Selector. Either string may be empty, which
// leaves the corresponding list nil (i.e. "match all" for Attach, "exclude
// nothing" for Exclude). An error is returned if any regex fails to compile.
func ParseSelector(attach, exclude string) (Selector, error) {
attachRegexes, err := parseRegexList(attach)
if err != nil {
return Selector{}, err
}
excludeRegexes, err := parseRegexList(exclude)
if err != nil {
return Selector{}, err
}
return Selector{Attach: attachRegexes, Exclude: excludeRegexes}, nil
}
// parseRegexList splits a comma-separated string of regex patterns and
// compiles each one. Returns nil (not an error) when the input is empty.
func parseRegexList(patterns string) ([]*regexp.Regexp, error) {
if len(patterns) == 0 {
return nil, nil
}
var regexes []*regexp.Regexp
for _, pattern := range strings.Split(patterns, ",") {
re, err := regexp.Compile(pattern)
if err != nil {
return nil, fmt.Errorf("unable to compile regex %q: %w", pattern, err)
}
regexes = append(regexes, re)
}
return regexes, nil
}
// ShouldAttach reports whether the given tracepoint name passes the
// selector's attach/exclude regex filters. Exclusions are checked first; if
// the name matches any exclude pattern it is rejected regardless of the attach
// list. When the attach list is empty, all non-excluded tracepoints are
// accepted.
func (s Selector) ShouldAttach(tracepointName string) bool {
for _, re := range s.Exclude {
if re.MatchString(tracepointName) {
return false
}
}
if len(s.Attach) == 0 {
if !s.RestrictSyscalls {
return true
}
syscall, ok := SyscallNameFromTracepoint(tracepointName)
if !ok {
return false
}
_, allowed := s.Syscalls[syscall]
return allowed
}
for _, re := range s.Attach {
if re.MatchString(tracepointName) {
if !s.RestrictSyscalls {
return true
}
syscall, ok := SyscallNameFromTracepoint(tracepointName)
if !ok {
return false
}
_, allowed := s.Syscalls[syscall]
return allowed
}
}
return false
}
// Clone returns a deep copy of the Selector so that modifications to the
// copy's slices do not affect the original.
func (s Selector) Clone() Selector {
return Selector{
Attach: slices.Clone(s.Attach),
Exclude: slices.Clone(s.Exclude),
Syscalls: maps.Clone(s.Syscalls),
RestrictSyscalls: s.RestrictSyscalls,
}
}
// SyscallNameFromTracepoint returns the bare syscall name for a tracepoint
// (for example "openat" from "sys_enter_openat").
func SyscallNameFromTracepoint(tracepointName string) (string, bool) {
switch {
case strings.HasPrefix(tracepointName, "sys_enter_"):
return strings.TrimPrefix(tracepointName, "sys_enter_"), true
case strings.HasPrefix(tracepointName, "sys_exit_"):
return strings.TrimPrefix(tracepointName, "sys_exit_"), true
default:
return "", false
}
}
|
