add local support for introspection service
Signed-off-by: Kathryn Baldauf <kabaldau@microsoft.com>
This commit is contained in:
Kathryn Baldauf
392
vendor/github.com/cilium/ebpf/elf_reader.go
generated
vendored
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392
vendor/github.com/cilium/ebpf/elf_reader.go
generated
vendored
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@@ -0,0 +1,392 @@
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package ebpf
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import (
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"bytes"
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"debug/elf"
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"encoding/binary"
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"fmt"
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"io"
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"os"
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"strings"
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"github.com/cilium/ebpf/asm"
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"github.com/pkg/errors"
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)
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type elfCode struct {
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*elf.File
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symbols []elf.Symbol
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symbolsPerSection map[elf.SectionIndex]map[uint64]string
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}
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// LoadCollectionSpec parses an ELF file into a CollectionSpec.
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func LoadCollectionSpec(file string) (*CollectionSpec, error) {
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f, err := os.Open(file)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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spec, err := LoadCollectionSpecFromReader(f)
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return spec, errors.Wrapf(err, "file %s", file)
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}
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// LoadCollectionSpecFromReader parses an ELF file into a CollectionSpec.
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func LoadCollectionSpecFromReader(code io.ReaderAt) (*CollectionSpec, error) {
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f, err := elf.NewFile(code)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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symbols, err := f.Symbols()
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if err != nil {
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return nil, errors.Wrap(err, "load symbols")
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}
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ec := &elfCode{f, symbols, symbolsPerSection(symbols)}
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var licenseSection, versionSection *elf.Section
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progSections := make(map[elf.SectionIndex]*elf.Section)
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relSections := make(map[elf.SectionIndex]*elf.Section)
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mapSections := make(map[elf.SectionIndex]*elf.Section)
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for i, sec := range ec.Sections {
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switch {
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case strings.HasPrefix(sec.Name, "license"):
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licenseSection = sec
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case strings.HasPrefix(sec.Name, "version"):
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versionSection = sec
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case strings.HasPrefix(sec.Name, "maps"):
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mapSections[elf.SectionIndex(i)] = sec
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case sec.Type == elf.SHT_REL:
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if int(sec.Info) >= len(ec.Sections) {
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return nil, errors.Errorf("found relocation section %v for missing section %v", i, sec.Info)
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}
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// Store relocations under the section index of the target
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idx := elf.SectionIndex(sec.Info)
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if relSections[idx] != nil {
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return nil, errors.Errorf("section %d has multiple relocation sections", idx)
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}
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relSections[idx] = sec
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case sec.Type == elf.SHT_PROGBITS && (sec.Flags&elf.SHF_EXECINSTR) != 0 && sec.Size > 0:
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progSections[elf.SectionIndex(i)] = sec
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}
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}
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license, err := loadLicense(licenseSection)
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if err != nil {
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return nil, errors.Wrap(err, "load license")
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}
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version, err := loadVersion(versionSection, ec.ByteOrder)
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if err != nil {
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return nil, errors.Wrap(err, "load version")
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}
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maps, err := ec.loadMaps(mapSections)
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if err != nil {
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return nil, errors.Wrap(err, "load maps")
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}
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progs, libs, err := ec.loadPrograms(progSections, relSections, license, version)
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if err != nil {
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return nil, errors.Wrap(err, "load programs")
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}
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if len(libs) > 0 {
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for name, prog := range progs {
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prog.Instructions, err = link(prog.Instructions, libs...)
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if err != nil {
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return nil, errors.Wrapf(err, "program %s", name)
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}
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}
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}
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return &CollectionSpec{maps, progs}, nil
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}
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func loadLicense(sec *elf.Section) (string, error) {
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if sec == nil {
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return "", errors.Errorf("missing license section")
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}
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data, err := sec.Data()
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if err != nil {
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return "", errors.Wrapf(err, "section %s", sec.Name)
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}
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return string(bytes.TrimRight(data, "\000")), nil
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}
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func loadVersion(sec *elf.Section, bo binary.ByteOrder) (uint32, error) {
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if sec == nil {
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return 0, nil
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}
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var version uint32
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err := binary.Read(sec.Open(), bo, &version)
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return version, errors.Wrapf(err, "section %s", sec.Name)
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}
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func (ec *elfCode) loadPrograms(progSections, relSections map[elf.SectionIndex]*elf.Section, license string, version uint32) (map[string]*ProgramSpec, []asm.Instructions, error) {
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var (
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progs = make(map[string]*ProgramSpec)
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libs []asm.Instructions
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)
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for idx, prog := range progSections {
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syms := ec.symbolsPerSection[idx]
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if len(syms) == 0 {
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return nil, nil, errors.Errorf("section %v: missing symbols", prog.Name)
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}
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funcSym := syms[0]
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if funcSym == "" {
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return nil, nil, errors.Errorf("section %v: no label at start", prog.Name)
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}
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rels, err := ec.loadRelocations(relSections[idx])
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if err != nil {
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return nil, nil, errors.Wrapf(err, "program %s: can't load relocations", funcSym)
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}
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insns, err := ec.loadInstructions(prog, syms, rels)
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if err != nil {
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return nil, nil, errors.Wrapf(err, "program %s: can't unmarshal instructions", funcSym)
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}
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if progType, attachType := getProgType(prog.Name); progType == UnspecifiedProgram {
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// There is no single name we can use for "library" sections,
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// since they may contain multiple functions. We'll decode the
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// labels they contain later on, and then link sections that way.
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libs = append(libs, insns)
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} else {
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progs[funcSym] = &ProgramSpec{
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Name: funcSym,
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Type: progType,
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AttachType: attachType,
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License: license,
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KernelVersion: version,
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Instructions: insns,
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}
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}
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}
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return progs, libs, nil
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}
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func (ec *elfCode) loadInstructions(section *elf.Section, symbols, relocations map[uint64]string) (asm.Instructions, error) {
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var (
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r = section.Open()
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insns asm.Instructions
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ins asm.Instruction
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offset uint64
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)
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for {
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n, err := ins.Unmarshal(r, ec.ByteOrder)
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if err == io.EOF {
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return insns, nil
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}
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if err != nil {
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return nil, errors.Wrapf(err, "offset %d", offset)
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}
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ins.Symbol = symbols[offset]
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ins.Reference = relocations[offset]
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insns = append(insns, ins)
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offset += n
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}
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}
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func (ec *elfCode) loadMaps(mapSections map[elf.SectionIndex]*elf.Section) (map[string]*MapSpec, error) {
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var (
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maps = make(map[string]*MapSpec)
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b = make([]byte, 1)
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)
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for idx, sec := range mapSections {
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syms := ec.symbolsPerSection[idx]
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if len(syms) == 0 {
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return nil, errors.Errorf("section %v: no symbols", sec.Name)
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}
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if sec.Size%uint64(len(syms)) != 0 {
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return nil, errors.Errorf("section %v: map descriptors are not of equal size", sec.Name)
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}
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var (
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r = sec.Open()
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size = sec.Size / uint64(len(syms))
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)
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for i, offset := 0, uint64(0); i < len(syms); i, offset = i+1, offset+size {
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mapSym := syms[offset]
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if mapSym == "" {
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fmt.Println(syms)
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return nil, errors.Errorf("section %s: missing symbol for map at offset %d", sec.Name, offset)
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}
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if maps[mapSym] != nil {
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return nil, errors.Errorf("section %v: map %v already exists", sec.Name, mapSym)
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}
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lr := io.LimitReader(r, int64(size))
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var spec MapSpec
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switch {
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case binary.Read(lr, ec.ByteOrder, &spec.Type) != nil:
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return nil, errors.Errorf("map %v: missing type", mapSym)
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case binary.Read(lr, ec.ByteOrder, &spec.KeySize) != nil:
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return nil, errors.Errorf("map %v: missing key size", mapSym)
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case binary.Read(lr, ec.ByteOrder, &spec.ValueSize) != nil:
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return nil, errors.Errorf("map %v: missing value size", mapSym)
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case binary.Read(lr, ec.ByteOrder, &spec.MaxEntries) != nil:
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return nil, errors.Errorf("map %v: missing max entries", mapSym)
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case binary.Read(lr, ec.ByteOrder, &spec.Flags) != nil:
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return nil, errors.Errorf("map %v: missing flags", mapSym)
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}
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for {
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_, err := lr.Read(b)
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if err == io.EOF {
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break
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}
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if err != nil {
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return nil, err
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}
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if b[0] != 0 {
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return nil, errors.Errorf("map %v: unknown and non-zero fields in definition", mapSym)
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}
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}
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maps[mapSym] = &spec
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}
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}
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return maps, nil
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}
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func getProgType(v string) (ProgramType, AttachType) {
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types := map[string]ProgramType{
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// From https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/lib/bpf/libbpf.c#n3568
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"socket": SocketFilter,
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"seccomp": SocketFilter,
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"kprobe/": Kprobe,
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"kretprobe/": Kprobe,
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"tracepoint/": TracePoint,
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"xdp": XDP,
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"perf_event": PerfEvent,
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"sockops": SockOps,
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"sk_skb": SkSKB,
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"sk_msg": SkMsg,
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"lirc_mode2": LircMode2,
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"flow_dissector": FlowDissector,
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"cgroup_skb/": CGroupSKB,
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"cgroup/dev": CGroupDevice,
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"cgroup/skb": CGroupSKB,
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"cgroup/sock": CGroupSock,
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"cgroup/post_bind": CGroupSock,
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"cgroup/bind": CGroupSockAddr,
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"cgroup/connect": CGroupSockAddr,
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"cgroup/sendmsg": CGroupSockAddr,
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"cgroup/recvmsg": CGroupSockAddr,
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"cgroup/sysctl": CGroupSysctl,
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"cgroup/getsockopt": CGroupSockopt,
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"cgroup/setsockopt": CGroupSockopt,
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"classifier": SchedCLS,
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"action": SchedACT,
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}
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attachTypes := map[string]AttachType{
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"cgroup_skb/ingress": AttachCGroupInetIngress,
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"cgroup_skb/egress": AttachCGroupInetEgress,
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"cgroup/sock": AttachCGroupInetSockCreate,
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"cgroup/post_bind4": AttachCGroupInet4PostBind,
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"cgroup/post_bind6": AttachCGroupInet6PostBind,
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"cgroup/dev": AttachCGroupDevice,
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"sockops": AttachCGroupSockOps,
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"sk_skb/stream_parser": AttachSkSKBStreamParser,
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"sk_skb/stream_verdict": AttachSkSKBStreamVerdict,
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"sk_msg": AttachSkSKBStreamVerdict,
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"lirc_mode2": AttachLircMode2,
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"flow_dissector": AttachFlowDissector,
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"cgroup/bind4": AttachCGroupInet4Bind,
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"cgroup/bind6": AttachCGroupInet6Bind,
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"cgroup/connect4": AttachCGroupInet4Connect,
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"cgroup/connect6": AttachCGroupInet6Connect,
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"cgroup/sendmsg4": AttachCGroupUDP4Sendmsg,
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"cgroup/sendmsg6": AttachCGroupUDP6Sendmsg,
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"cgroup/recvmsg4": AttachCGroupUDP4Recvmsg,
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"cgroup/recvmsg6": AttachCGroupUDP6Recvmsg,
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"cgroup/sysctl": AttachCGroupSysctl,
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"cgroup/getsockopt": AttachCGroupGetsockopt,
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"cgroup/setsockopt": AttachCGroupSetsockopt,
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}
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attachType := AttachNone
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for k, t := range attachTypes {
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if strings.HasPrefix(v, k) {
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attachType = t
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}
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}
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for k, t := range types {
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if strings.HasPrefix(v, k) {
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return t, attachType
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}
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}
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return UnspecifiedProgram, AttachNone
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}
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func (ec *elfCode) loadRelocations(sec *elf.Section) (map[uint64]string, error) {
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rels := make(map[uint64]string)
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if sec == nil {
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return rels, nil
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}
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if sec.Entsize < 16 {
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return nil, errors.New("rels are less than 16 bytes")
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}
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r := sec.Open()
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for off := uint64(0); off < sec.Size; off += sec.Entsize {
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ent := io.LimitReader(r, int64(sec.Entsize))
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var rel elf.Rel64
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if binary.Read(ent, ec.ByteOrder, &rel) != nil {
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return nil, errors.Errorf("can't parse relocation at offset %v", off)
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}
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symNo := int(elf.R_SYM64(rel.Info) - 1)
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if symNo >= len(ec.symbols) {
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return nil, errors.Errorf("relocation at offset %d: symbol %v doesnt exist", off, symNo)
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}
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rels[rel.Off] = ec.symbols[symNo].Name
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}
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return rels, nil
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}
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func symbolsPerSection(symbols []elf.Symbol) map[elf.SectionIndex]map[uint64]string {
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result := make(map[elf.SectionIndex]map[uint64]string)
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for i, sym := range symbols {
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switch elf.ST_TYPE(sym.Info) {
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case elf.STT_NOTYPE:
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// Older versions of LLVM doesn't tag
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// symbols correctly.
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break
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case elf.STT_OBJECT:
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break
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case elf.STT_FUNC:
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break
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default:
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continue
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}
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if sym.Name == "" {
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continue
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}
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idx := sym.Section
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if _, ok := result[idx]; !ok {
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result[idx] = make(map[uint64]string)
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}
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result[idx][sym.Value] = symbols[i].Name
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}
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return result
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}
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