86 lines
1.9 KiB
Go
86 lines
1.9 KiB
Go
package link
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import (
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"fmt"
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"io"
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"unsafe"
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"github.com/cilium/ebpf"
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"github.com/cilium/ebpf/internal/sys"
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)
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type IterOptions struct {
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// Program must be of type Tracing with attach type
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// AttachTraceIter. The kind of iterator to attach to is
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// determined at load time via the AttachTo field.
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//
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// AttachTo requires the kernel to include BTF of itself,
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// and it to be compiled with a recent pahole (>= 1.16).
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Program *ebpf.Program
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// Map specifies the target map for bpf_map_elem and sockmap iterators.
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// It may be nil.
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Map *ebpf.Map
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}
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// AttachIter attaches a BPF seq_file iterator.
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func AttachIter(opts IterOptions) (*Iter, error) {
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if err := haveBPFLink(); err != nil {
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return nil, err
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}
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progFd := opts.Program.FD()
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if progFd < 0 {
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return nil, fmt.Errorf("invalid program: %s", sys.ErrClosedFd)
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}
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var info bpfIterLinkInfoMap
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if opts.Map != nil {
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mapFd := opts.Map.FD()
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if mapFd < 0 {
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return nil, fmt.Errorf("invalid map: %w", sys.ErrClosedFd)
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}
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info.map_fd = uint32(mapFd)
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}
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attr := sys.LinkCreateIterAttr{
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ProgFd: uint32(progFd),
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AttachType: sys.AttachType(ebpf.AttachTraceIter),
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IterInfo: sys.NewPointer(unsafe.Pointer(&info)),
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IterInfoLen: uint32(unsafe.Sizeof(info)),
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}
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fd, err := sys.LinkCreateIter(&attr)
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if err != nil {
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return nil, fmt.Errorf("can't link iterator: %w", err)
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}
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return &Iter{RawLink{fd, ""}}, err
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}
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// Iter represents an attached bpf_iter.
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type Iter struct {
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RawLink
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}
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// Open creates a new instance of the iterator.
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//
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// Reading from the returned reader triggers the BPF program.
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func (it *Iter) Open() (io.ReadCloser, error) {
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attr := &sys.IterCreateAttr{
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LinkFd: it.fd.Uint(),
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}
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fd, err := sys.IterCreate(attr)
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if err != nil {
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return nil, fmt.Errorf("can't create iterator: %w", err)
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}
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return fd.File("bpf_iter"), nil
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}
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// union bpf_iter_link_info.map
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type bpfIterLinkInfoMap struct {
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map_fd uint32
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}
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