mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-12 10:00:46 +01:00
170 lines
3.6 KiB
Go
170 lines
3.6 KiB
Go
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package link
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import (
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"errors"
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"fmt"
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"os"
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"github.com/cilium/ebpf"
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)
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type cgroupAttachFlags uint32
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// cgroup attach flags
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const (
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flagAllowOverride cgroupAttachFlags = 1 << iota
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flagAllowMulti
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flagReplace
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)
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type CgroupOptions struct {
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// Path to a cgroupv2 folder.
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Path string
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// One of the AttachCgroup* constants
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Attach ebpf.AttachType
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// Program must be of type CGroup*, and the attach type must match Attach.
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Program *ebpf.Program
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}
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// AttachCgroup links a BPF program to a cgroup.
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func AttachCgroup(opts CgroupOptions) (Link, error) {
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cgroup, err := os.Open(opts.Path)
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if err != nil {
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return nil, fmt.Errorf("can't open cgroup: %s", err)
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}
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clone, err := opts.Program.Clone()
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if err != nil {
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cgroup.Close()
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return nil, err
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}
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var cg Link
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cg, err = newLinkCgroup(cgroup, opts.Attach, clone)
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if errors.Is(err, ErrNotSupported) {
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cg, err = newProgAttachCgroup(cgroup, opts.Attach, clone, flagAllowMulti)
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}
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if errors.Is(err, ErrNotSupported) {
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cg, err = newProgAttachCgroup(cgroup, opts.Attach, clone, flagAllowOverride)
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}
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if err != nil {
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cgroup.Close()
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clone.Close()
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return nil, err
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}
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return cg, nil
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}
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// LoadPinnedCgroup loads a pinned cgroup from a bpffs.
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func LoadPinnedCgroup(fileName string) (Link, error) {
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link, err := LoadPinnedRawLink(fileName)
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if err != nil {
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return nil, err
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}
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return &linkCgroup{link}, nil
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}
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type progAttachCgroup struct {
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cgroup *os.File
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current *ebpf.Program
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attachType ebpf.AttachType
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flags cgroupAttachFlags
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}
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var _ Link = (*progAttachCgroup)(nil)
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func (cg *progAttachCgroup) isLink() {}
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func newProgAttachCgroup(cgroup *os.File, attach ebpf.AttachType, prog *ebpf.Program, flags cgroupAttachFlags) (*progAttachCgroup, error) {
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if flags&flagAllowMulti > 0 {
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if err := haveProgAttachReplace(); err != nil {
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return nil, fmt.Errorf("can't support multiple programs: %w", err)
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}
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}
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err := RawAttachProgram(RawAttachProgramOptions{
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Target: int(cgroup.Fd()),
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Program: prog,
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Flags: uint32(flags),
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Attach: attach,
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})
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if err != nil {
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return nil, fmt.Errorf("cgroup: %w", err)
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}
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return &progAttachCgroup{cgroup, prog, attach, flags}, nil
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}
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func (cg *progAttachCgroup) Close() error {
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defer cg.cgroup.Close()
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defer cg.current.Close()
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err := RawDetachProgram(RawDetachProgramOptions{
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Target: int(cg.cgroup.Fd()),
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Program: cg.current,
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Attach: cg.attachType,
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})
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if err != nil {
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return fmt.Errorf("close cgroup: %s", err)
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}
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return nil
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}
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func (cg *progAttachCgroup) Update(prog *ebpf.Program) error {
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new, err := prog.Clone()
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if err != nil {
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return err
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}
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args := RawAttachProgramOptions{
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Target: int(cg.cgroup.Fd()),
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Program: prog,
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Attach: cg.attachType,
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Flags: uint32(cg.flags),
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}
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if cg.flags&flagAllowMulti > 0 {
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// Atomically replacing multiple programs requires at least
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// 5.5 (commit 7dd68b3279f17921 "bpf: Support replacing cgroup-bpf
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// program in MULTI mode")
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args.Flags |= uint32(flagReplace)
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args.Replace = cg.current
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}
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if err := RawAttachProgram(args); err != nil {
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new.Close()
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return fmt.Errorf("can't update cgroup: %s", err)
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}
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cg.current.Close()
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cg.current = new
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return nil
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}
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func (cg *progAttachCgroup) Pin(string) error {
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return fmt.Errorf("can't pin cgroup: %w", ErrNotSupported)
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}
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type linkCgroup struct {
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*RawLink
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}
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var _ Link = (*linkCgroup)(nil)
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func (cg *linkCgroup) isLink() {}
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func newLinkCgroup(cgroup *os.File, attach ebpf.AttachType, prog *ebpf.Program) (*linkCgroup, error) {
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link, err := AttachRawLink(RawLinkOptions{
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Target: int(cgroup.Fd()),
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Program: prog,
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Attach: attach,
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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 &linkCgroup{link}, err
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}
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