secret_linux.go RawHistoryFolder

1package auth
2
3import "golang.org/x/sys/unix"
4
5// secretBuffer owns a dedicated anonymous page, not a Go heap page shared with
6// GC/runtime objects. The logical capacity is fixed (PIN 32, credential 512).
7// mlock is best effort; no promise covers transient codec/PAM bridge copies.
8type secretBuffer struct {
9	page   []byte
10	data   []byte
11	locked bool
12}
13
14func newSecret(size int) (*secretBuffer, error) {
15	if size < 1 || size > 512 {
16		return nil, ErrProtocol
17	}
18	page, err := unix.Mmap(-1, 0, unix.Getpagesize(), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_PRIVATE|unix.MAP_ANON)
19	if err != nil {
20		return nil, errSource
21	}
22	return &secretBuffer{page: page, data: page[:size:size], locked: unix.Mlock(page) == nil}, nil
23}
24
25func (b *secretBuffer) close() {
26	if b == nil || b.page == nil {
27		return
28	}
29	clear(b.page)
30	if b.locked {
31		unix.Munlock(b.page)
32	}
33	unix.Munmap(b.page)
34	b.page, b.data = nil, nil
35}