hardcoresushi/libgocryptfs
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Make -openssl also apply to xchacha

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Now that stupidgcm supports xchacha, make it available
on mount.
This commit is contained in:
Jakob Unterwurzacher 2021-09-08 20:32:16 +02:00
parent 1a58667293
commit 94e8004b6c
3 changed files with 31 additions and 8 deletions
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6
cli_args.go
View File

@ -253,7 +253,11 @@ func parseCliOpts(osArgs []string) (args argContainer) {
}
// "-openssl" needs some post-processing
if opensslAuto == "auto" {
args.openssl = stupidgcm.PreferOpenSSLAES256GCM()
if args.xchacha {
args.openssl = stupidgcm.PreferOpenSSLXchacha20poly1305()
} else {
args.openssl = stupidgcm.PreferOpenSSLAES256GCM()
}
} else {
args.openssl, err = strconv.ParseBool(opensslAuto)
if err != nil {

16
internal/cryptocore/cryptocore.go
View File

@ -32,11 +32,11 @@ type AEADTypeEnum struct {
NonceSize int
}
// BackendOpenSSL specifies the OpenSSL backend.
// BackendOpenSSL specifies the OpenSSL AES-256-GCM backend.
// "AES-GCM-256-OpenSSL" in gocryptfs -speed.
var BackendOpenSSL AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-OpenSSL", 16}
// BackendGoGCM specifies the Go based GCM backend.
// BackendGoGCM specifies the Go based AES-256-GCM backend.
// "AES-GCM-256-Go" in gocryptfs -speed.
var BackendGoGCM AEADTypeEnum = AEADTypeEnum{"AES-GCM-256-Go", 16}
@ -130,6 +130,8 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if err != nil {
log.Panic(err)
}
default:
log.Panicf("BUG: unhandled case: %v", aeadType)
}
for i := range gcmKey {
gcmKey[i] = 0
@ -154,7 +156,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
for i := range key64 {
key64[i] = 0
}
} else if aeadType == BackendXChaCha20Poly1305 {
} else if aeadType == BackendXChaCha20Poly1305 || aeadType == BackendXChaCha20Poly1305OpenSSL {
// We don't support legacy modes with XChaCha20-Poly1305
if IVBitLen != chacha20poly1305.NonceSizeX*8 {
log.Panicf("XChaCha20-Poly1305 must use 192-bit IVs, you wanted %d", IVBitLen)
@ -163,7 +165,13 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
log.Panic("XChaCha20-Poly1305 must use HKDF, but it is disabled")
}
derivedKey := hkdfDerive(key, hkdfInfoXChaChaPoly1305Content, chacha20poly1305.KeySize)
aeadCipher, err = chacha20poly1305.NewX(derivedKey)
if aeadType == BackendXChaCha20Poly1305 {
aeadCipher, err = chacha20poly1305.NewX(derivedKey)
} else if aeadType == BackendXChaCha20Poly1305OpenSSL {
aeadCipher = stupidgcm.NewXchacha20poly1305(derivedKey)
} else {
log.Panicf("BUG: unhandled case: %v", aeadType)
}
if err != nil {
log.Panic(err)
}

17
mount.go
View File

@ -259,7 +259,11 @@ func initFuseFrontend(args *argContainer) (rootNode fs.InodeEmbedder, wipeKeys f
cryptoBackend = cryptocore.BackendAESSIV
}
if args.xchacha {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305
if args.openssl {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305OpenSSL
} else {
cryptoBackend = cryptocore.BackendXChaCha20Poly1305
}
IVBits = chacha20poly1305.NonceSizeX * 8
}
// forceOwner implies allow_other, as documented.
@ -291,6 +295,7 @@ func initFuseFrontend(args *argContainer) (rootNode fs.InodeEmbedder, wipeKeys f
frontendArgs.DeterministicNames = !confFile.IsFeatureFlagSet(configfile.FlagDirIV)
args.raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
args.hkdf = confFile.IsFeatureFlagSet(configfile.FlagHKDF)
// Note: this will always return the non-openssl variant
cryptoBackend, err = confFile.ContentEncryption()
if err != nil {
tlog.Fatal.Printf("%v", err)
@ -301,8 +306,14 @@ func initFuseFrontend(args *argContainer) (rootNode fs.InodeEmbedder, wipeKeys f
tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
os.Exit(exitcodes.Usage)
}
if cryptoBackend == cryptocore.BackendGoGCM && args.openssl {
cryptoBackend = cryptocore.BackendOpenSSL
// Upgrade to OpenSSL variant if requested
if args.openssl {
switch cryptoBackend {
case cryptocore.BackendGoGCM:
cryptoBackend = cryptocore.BackendOpenSSL
case cryptocore.BackendXChaCha20Poly1305:
cryptoBackend = cryptocore.BackendXChaCha20Poly1305OpenSSL
}
}
}
// If allow_other is set and we run as root, try to give newly created files to