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go_hooks.go
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go_hooks.go
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package main
import (
"github.com/cilium/ebpf/link"
"github.com/go-errors/errors"
)
type goHooks struct {
goWriteProbe link.Link
goWriteExProbes []link.Link
goReadProbe link.Link
goReadExProbes []link.Link
}
func (s *goHooks) installUprobes(bpfObjects *tracerObjects, fpath string) (offsets goOffsets, err error) {
ex, err := link.OpenExecutable(fpath)
if err != nil {
err = errors.Wrap(err, 0)
return
}
offsets, err = findGoOffsets(fpath)
if err != nil {
err = errors.Wrap(err, 0)
return
}
err = s.installHooks(bpfObjects, ex, offsets)
return
}
func (s *goHooks) installHooks(bpfObjects *tracerObjects, ex *link.Executable, offsets goOffsets) error {
var err error
goCryptoTlsWrite := bpfObjects.GoCryptoTlsAbiInternalWrite
goCryptoTlsWriteEx := bpfObjects.GoCryptoTlsAbiInternalWriteEx
goCryptoTlsRead := bpfObjects.GoCryptoTlsAbiInternalRead
goCryptoTlsReadEx := bpfObjects.GoCryptoTlsAbiInternalReadEx
if offsets.Abi == ABI0 {
goCryptoTlsWrite = bpfObjects.GoCryptoTlsAbi0Write
goCryptoTlsWriteEx = bpfObjects.GoCryptoTlsAbi0WriteEx
goCryptoTlsRead = bpfObjects.GoCryptoTlsAbi0Read
goCryptoTlsReadEx = bpfObjects.GoCryptoTlsAbi0ReadEx
// Pass goid and g struct offsets to an eBPF map to retrieve it in eBPF context
if err := bpfObjects.tracerMaps.GoidOffsetsMap.Put(
uint32(0),
tracerGoidOffsets{
G_addrOffset: offsets.GStructOffset,
GoidOffset: offsets.GoidOffset,
},
); err != nil {
return errors.Wrap(err, 0)
}
}
// Symbol points to
// [`crypto/tls.(*Conn).Write`](https://github.com/golang/go/blob/go1.17.6/src/crypto/tls/conn.go#L1099)
s.goWriteProbe, err = ex.Uprobe(goWriteSymbol, goCryptoTlsWrite, &link.UprobeOptions{
Address: offsets.GoWriteOffset.enter,
})
if err != nil {
return errors.Wrap(err, 0)
}
for _, offset := range offsets.GoWriteOffset.exits {
probe, err := ex.Uprobe(goWriteSymbol, goCryptoTlsWriteEx, &link.UprobeOptions{
Address: offset,
})
if err != nil {
return errors.Wrap(err, 0)
}
s.goWriteExProbes = append(s.goWriteExProbes, probe)
}
// Symbol points to
// [`crypto/tls.(*Conn).Read`](https://github.com/golang/go/blob/go1.17.6/src/crypto/tls/conn.go#L1263)
s.goReadProbe, err = ex.Uprobe(goReadSymbol, goCryptoTlsRead, &link.UprobeOptions{
Address: offsets.GoReadOffset.enter,
})
if err != nil {
return errors.Wrap(err, 0)
}
for _, offset := range offsets.GoReadOffset.exits {
probe, err := ex.Uprobe(goReadSymbol, goCryptoTlsReadEx, &link.UprobeOptions{
Address: offset,
})
if err != nil {
return errors.Wrap(err, 0)
}
s.goReadExProbes = append(s.goReadExProbes, probe)
}
return nil
}
func (s *goHooks) close() []error {
errors := make([]error, 0)
if err := s.goWriteProbe.Close(); err != nil {
errors = append(errors, err)
}
for _, probe := range s.goWriteExProbes {
if err := probe.Close(); err != nil {
errors = append(errors, err)
}
}
if err := s.goReadProbe.Close(); err != nil {
errors = append(errors, err)
}
for _, probe := range s.goReadExProbes {
if err := probe.Close(); err != nil {
errors = append(errors, err)
}
}
return errors
}