89 lines
2.2 KiB
Go
89 lines
2.2 KiB
Go
package link
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import (
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"fmt"
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"github.com/cilium/ebpf"
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"github.com/cilium/ebpf/internal/btf"
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)
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type FreplaceLink struct {
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RawLink
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}
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// AttachFreplace attaches the given eBPF program to the function it replaces.
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//
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// The program and name can either be provided at link time, or can be provided
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// at program load time. If they were provided at load time, they should be nil
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// and empty respectively here, as they will be ignored by the kernel.
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// Examples:
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//
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// AttachFreplace(dispatcher, "function", replacement)
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// AttachFreplace(nil, "", replacement)
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func AttachFreplace(targetProg *ebpf.Program, name string, prog *ebpf.Program) (*FreplaceLink, error) {
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if (name == "") != (targetProg == nil) {
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return nil, fmt.Errorf("must provide both or neither of name and targetProg: %w", errInvalidInput)
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}
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if prog == nil {
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return nil, fmt.Errorf("prog cannot be nil: %w", errInvalidInput)
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}
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if prog.Type() != ebpf.Extension {
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return nil, fmt.Errorf("eBPF program type %s is not an Extension: %w", prog.Type(), errInvalidInput)
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}
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var (
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target int
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typeID btf.TypeID
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)
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if targetProg != nil {
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info, err := targetProg.Info()
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if err != nil {
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return nil, err
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}
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btfID, ok := info.BTFID()
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if !ok {
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return nil, fmt.Errorf("could not get BTF ID for program %s: %w", info.Name, errInvalidInput)
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}
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btfHandle, err := btf.NewHandleFromID(btfID)
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if err != nil {
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return nil, err
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}
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defer btfHandle.Close()
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var function *btf.Func
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if err := btfHandle.Spec().FindType(name, &function); err != nil {
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return nil, err
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}
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target = targetProg.FD()
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typeID = function.ID()
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}
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link, err := AttachRawLink(RawLinkOptions{
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Target: target,
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Program: prog,
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Attach: ebpf.AttachNone,
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BTF: typeID,
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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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return &FreplaceLink{*link}, nil
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}
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// Update implements the Link interface.
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func (f *FreplaceLink) Update(new *ebpf.Program) error {
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return fmt.Errorf("freplace update: %w", ErrNotSupported)
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}
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// LoadPinnedFreplace loads a pinned iterator from a bpffs.
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func LoadPinnedFreplace(fileName string, opts *ebpf.LoadPinOptions) (*FreplaceLink, error) {
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link, err := LoadPinnedRawLink(fileName, TracingType, opts)
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if err != nil {
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return nil, err
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}
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return &FreplaceLink{*link}, err
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}
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