CVE-2019-11840

snapd contains an embedded copy of golang-go.crypto with the
affected code
snapd doesn't import/use the salsa code directly, but does vendor
golang-gopkg-macaroon.v1, which imports golang.org/x/crypto/nacl/secretbox
which does import salsa and contains the affected salsa2020XORKeyStream.
snapd uses secretbox.Open() and secretbox.Seal(), both of which use
salsa.XORKeyStream() (which wraps salsa2020XORKeyStream) via the internal
decrypt() and encrypt() functions, respectively. In macaroon.v1, encrypt() is
only used via AddThirdPartyCaveat() and decrypt() via Verify().
.
overlord/auth/auth.go in snapd uses Verify() in CheckMacaroon(),
daemon/api.go uses CheckMacaroon() in UserFromRequest(), which is called by
ServeHTTP(), the service used to process snap commands from the local system
to the local snapd. This CVE does not affect decrypt() operations.
.
AddThirdPartyCaveat() is only used in unit tests, but not in the binaries of
snapd builds.
.
For snapd, ignoring since only encryption operations (ie, secretbox.Seal())
are affected with regard to loss of confidentiality/predictability and this
function is only ever (ultimately) called via the snapd unit tests.
lxd contains an embedded copy of golang-go.crypto, but does not
import golang.org/x/crypto/nacl/secretbox or salsa. lxd in cosmic and later
does not contain the affected code.