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-rw-r--r--include/linux/sunrpc/gss_krb5_enctypes.h42
-rw-r--r--net/sunrpc/Kconfig16
-rw-r--r--net/sunrpc/auth_gss/gss_krb5_mech.c2
3 files changed, 59 insertions, 1 deletions
diff --git a/include/linux/sunrpc/gss_krb5_enctypes.h b/include/linux/sunrpc/gss_krb5_enctypes.h
index ec6234eee89c..981c89cef19d 100644
--- a/include/linux/sunrpc/gss_krb5_enctypes.h
+++ b/include/linux/sunrpc/gss_krb5_enctypes.h
@@ -1,4 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
/*
- * Dumb way to share this static piece of information with nfsd
+ * Define the string that exports the set of kernel-supported
+ * Kerberos enctypes. This list is sent via upcall to gssd, and
+ * is also exposed via the nfsd /proc API. The consumers generally
+ * treat this as an ordered list, where the first item in the list
+ * is the most preferred.
+ */
+
+#ifndef _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H
+#define _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H
+
+#ifdef CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES
+
+/*
+ * NB: This list includes encryption types that were deprecated
+ * by RFC 8429 (DES3_CBC_SHA1 and ARCFOUR_HMAC).
+ *
+ * ENCTYPE_AES256_CTS_HMAC_SHA1_96
+ * ENCTYPE_AES128_CTS_HMAC_SHA1_96
+ * ENCTYPE_DES3_CBC_SHA1
+ * ENCTYPE_ARCFOUR_HMAC
+ */
+#define KRB5_SUPPORTED_ENCTYPES "18,17,16,23"
+
+#else /* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
+
+/*
+ * NB: This list includes encryption types that were deprecated
+ * by RFC 8429 and RFC 6649.
+ *
+ * ENCTYPE_AES256_CTS_HMAC_SHA1_96
+ * ENCTYPE_AES128_CTS_HMAC_SHA1_96
+ * ENCTYPE_DES3_CBC_SHA1
+ * ENCTYPE_ARCFOUR_HMAC
+ * ENCTYPE_DES_CBC_MD5
+ * ENCTYPE_DES_CBC_CRC
+ * ENCTYPE_DES_CBC_MD4
*/
#define KRB5_SUPPORTED_ENCTYPES "18,17,16,23,3,1,2"
+
+#endif /* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
+
+#endif /* _LINUX_SUNRPC_GSS_KRB5_ENCTYPES_H */
diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index ac09ca803296..83f5617bae07 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -34,6 +34,22 @@ config RPCSEC_GSS_KRB5
If unsure, say Y.
+config CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES
+ bool "Secure RPC: Disable insecure Kerberos encryption types"
+ depends on RPCSEC_GSS_KRB5
+ default n
+ help
+ Choose Y here to disable the use of deprecated encryption types
+ with the Kerberos version 5 GSS-API mechanism (RFC 1964). The
+ deprecated encryption types include DES-CBC-MD5, DES-CBC-CRC,
+ and DES-CBC-MD4. These types were deprecated by RFC 6649 because
+ they were found to be insecure.
+
+ N is the default because many sites have deployed KDCs and
+ keytabs that contain only these deprecated encryption types.
+ Choosing Y prevents the use of known-insecure encryption types
+ but might result in compatibility problems.
+
config SUNRPC_DEBUG
bool "RPC: Enable dprintk debugging"
depends on SUNRPC && SYSCTL
diff --git a/net/sunrpc/auth_gss/gss_krb5_mech.c b/net/sunrpc/auth_gss/gss_krb5_mech.c
index eab71fc7af3e..be31a58d54e0 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
@@ -53,6 +53,7 @@
static struct gss_api_mech gss_kerberos_mech; /* forward declaration */
static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
+#ifndef CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES
/*
* DES (All DES enctypes are mapped to the same gss functionality)
*/
@@ -74,6 +75,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = {
.cksumlength = 8,
.keyed_cksum = 0,
},
+#endif /* CONFIG_SUNRPC_DISABLE_INSECURE_ENCTYPES */
/*
* RC4-HMAC
*/