mirror of
https://github.com/opencontainers/runc.git
synced 2026-07-11 06:03:57 +08:00
Rafael Roquetto
112 lines
3.3 KiB
Go
112 lines
3.3 KiB
Go
package link
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import (
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"fmt"
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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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// QueryOptions defines additional parameters when querying for programs.
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type QueryOptions struct {
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// Target to query. This is usually a file descriptor but may refer to
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// something else based on the attach type.
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Target int
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// Attach specifies the AttachType of the programs queried for
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Attach ebpf.AttachType
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// QueryFlags are flags for BPF_PROG_QUERY, e.g. BPF_F_QUERY_EFFECTIVE
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QueryFlags uint32
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}
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// QueryResult describes which programs and links are active.
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type QueryResult struct {
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// List of attached programs.
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Programs []AttachedProgram
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// Incremented by one every time the set of attached programs changes.
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// May be zero if not supported by the [ebpf.AttachType].
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Revision uint64
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}
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// HaveLinkInfo returns true if the kernel supports querying link information
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// for a particular [ebpf.AttachType].
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func (qr *QueryResult) HaveLinkInfo() bool {
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return qr.Revision > 0
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}
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type AttachedProgram struct {
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ID ebpf.ProgramID
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linkID ID
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}
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// LinkID returns the ID associated with the program.
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//
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// Returns 0, false if the kernel doesn't support retrieving the ID or if the
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// program wasn't attached via a link. See [QueryResult.HaveLinkInfo] if you
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// need to tell the two apart.
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func (ap *AttachedProgram) LinkID() (ID, bool) {
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return ap.linkID, ap.linkID != 0
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}
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// QueryPrograms retrieves a list of programs for the given AttachType.
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//
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// Returns a slice of attached programs, which may be empty.
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// revision counts how many times the set of attached programs has changed and
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// may be zero if not supported by the [ebpf.AttachType].
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// Returns ErrNotSupportd on a kernel without BPF_PROG_QUERY
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func QueryPrograms(opts QueryOptions) (*QueryResult, error) {
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// query the number of programs to allocate correct slice size
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attr := sys.ProgQueryAttr{
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TargetFdOrIfindex: uint32(opts.Target),
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AttachType: sys.AttachType(opts.Attach),
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QueryFlags: opts.QueryFlags,
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}
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err := sys.ProgQuery(&attr)
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if err != nil {
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if haveFeatErr := haveProgQuery(); haveFeatErr != nil {
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return nil, fmt.Errorf("query programs: %w", haveFeatErr)
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}
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return nil, fmt.Errorf("query programs: %w", err)
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}
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if attr.Count == 0 {
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return &QueryResult{Revision: attr.Revision}, nil
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}
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// The minimum bpf_mprog revision is 1, so we can use the field to detect
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// whether the attach type supports link ids.
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haveLinkIDs := attr.Revision != 0
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count := attr.Count
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progIds := make([]ebpf.ProgramID, count)
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attr = sys.ProgQueryAttr{
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TargetFdOrIfindex: uint32(opts.Target),
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AttachType: sys.AttachType(opts.Attach),
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QueryFlags: opts.QueryFlags,
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Count: count,
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ProgIds: sys.NewPointer(unsafe.Pointer(&progIds[0])),
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}
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var linkIds []ID
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if haveLinkIDs {
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linkIds = make([]ID, count)
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attr.LinkIds = sys.NewPointer(unsafe.Pointer(&linkIds[0]))
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}
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if err := sys.ProgQuery(&attr); err != nil {
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return nil, fmt.Errorf("query programs: %w", err)
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}
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// NB: attr.Count might have changed between the two syscalls.
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var programs []AttachedProgram
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for i, id := range progIds[:attr.Count] {
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ap := AttachedProgram{ID: id}
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if haveLinkIDs {
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ap.linkID = linkIds[i]
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}
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programs = append(programs, ap)
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}
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return &QueryResult{programs, attr.Revision}, nil
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}
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