[PATCH 16/18] SUNRPC: Remove per-enctype Kconfig options

[Chuck Lever]

From: Chuck Lever <chuck.lever@xxxxxxxxxx>

The RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA1,
RPCSEC_GSS_KRB5_ENCTYPES_CAMELLIA, and
RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2 Kconfig options
originally gated both algorithm availability and the
advertised enctype list. Now that per-message crypto
operations are routed through crypto/krb5, these options
control only which enctype numbers appear in the gssd
upcall string; the underlying algorithms are always
present.

Remove the per-enctype Kconfig options and replace the
ifdef-gated enctype table with a candidate list looked
up in the crypto/krb5 enctype table at module init
time. Each enctype is included in the advertised list
only if crypto_krb5_find_enctype() finds it in the
library's enctype table. When a new enctype is added
to crypto/krb5, adding its constant to the candidate
array is sufficient to begin advertising it.

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 net/sunrpc/Kconfig                  | 38 -------------------------------------
 net/sunrpc/auth_gss/gss_krb5_mech.c | 30 ++++++++++++++---------------
 2 files changed, 14 insertions(+), 54 deletions(-)

diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
index 1c2e1fe9d365..305c55cdbd45 100644
--- a/net/sunrpc/Kconfig
+++ b/net/sunrpc/Kconfig
@@ -35,44 +35,6 @@ config RPCSEC_GSS_KRB5
 
 	  If unsure, say Y.
 
-config RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA1
-	bool "Enable Kerberos enctypes based on AES and SHA-1"
-	depends on RPCSEC_GSS_KRB5
-	depends on CRYPTO_CBC && CRYPTO_CTS
-	depends on CRYPTO_HMAC && CRYPTO_SHA1
-	depends on CRYPTO_AES
-	default y
-	help
-	  Choose Y to enable the use of Kerberos 5 encryption types
-	  that utilize Advanced Encryption Standard (AES) ciphers and
-	  SHA-1 digests. These include aes128-cts-hmac-sha1-96 and
-	  aes256-cts-hmac-sha1-96.
-
-config RPCSEC_GSS_KRB5_ENCTYPES_CAMELLIA
-	bool "Enable Kerberos encryption types based on Camellia and CMAC"
-	depends on RPCSEC_GSS_KRB5
-	depends on CRYPTO_CBC && CRYPTO_CTS && CRYPTO_CAMELLIA
-	depends on CRYPTO_CMAC
-	default n
-	help
-	  Choose Y to enable the use of Kerberos 5 encryption types
-	  that utilize Camellia ciphers (RFC 3713) and CMAC digests
-	  (NIST Special Publication 800-38B). These include
-	  camellia128-cts-cmac and camellia256-cts-cmac.
-
-config RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2
-	bool "Enable Kerberos enctypes based on AES and SHA-2"
-	depends on RPCSEC_GSS_KRB5
-	depends on CRYPTO_CBC && CRYPTO_CTS
-	depends on CRYPTO_HMAC && CRYPTO_SHA256 && CRYPTO_SHA512
-	depends on CRYPTO_AES
-	default n
-	help
-	  Choose Y to enable the use of Kerberos 5 encryption types
-	  that utilize Advanced Encryption Standard (AES) ciphers and
-	  SHA-2 digests. These include aes128-cts-hmac-sha256-128 and
-	  aes256-cts-hmac-sha384-192.
-
 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 5a52fd84f946..996e452b9b3c 100644
--- a/net/sunrpc/auth_gss/gss_krb5_mech.c
+++ b/net/sunrpc/auth_gss/gss_krb5_mech.c
@@ -28,27 +28,23 @@
 static struct gss_api_mech gss_kerberos_mech;
 
 /*
- * The list of advertised enctypes is specified in order of most
- * preferred to least.
+ * Candidate enctypes in order of most preferred to least.
+ * Each is probed against crypto/krb5 at module init; only
+ * enctypes that crypto/krb5 supports are advertised.
  */
+static const u32 gss_krb5_enctypes[] = {
+	ENCTYPE_AES256_CTS_HMAC_SHA384_192,
+	ENCTYPE_AES128_CTS_HMAC_SHA256_128,
+	ENCTYPE_CAMELLIA256_CTS_CMAC,
+	ENCTYPE_CAMELLIA128_CTS_CMAC,
+	ENCTYPE_AES256_CTS_HMAC_SHA1_96,
+	ENCTYPE_AES128_CTS_HMAC_SHA1_96,
+};
+
 static char gss_krb5_enctype_priority_list[64];
 
 static void gss_krb5_prepare_enctype_priority_list(void)
 {
-	static const u32 gss_krb5_enctypes[] = {
-#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA2)
-		ENCTYPE_AES256_CTS_HMAC_SHA384_192,
-		ENCTYPE_AES128_CTS_HMAC_SHA256_128,
-#endif
-#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_CAMELLIA)
-		ENCTYPE_CAMELLIA256_CTS_CMAC,
-		ENCTYPE_CAMELLIA128_CTS_CMAC,
-#endif
-#if defined(CONFIG_RPCSEC_GSS_KRB5_ENCTYPES_AES_SHA1)
-		ENCTYPE_AES256_CTS_HMAC_SHA1_96,
-		ENCTYPE_AES128_CTS_HMAC_SHA1_96,
-#endif
-	};
 	size_t total, i;
 	char buf[16];
 	char *sep;
@@ -57,6 +53,8 @@ static void gss_krb5_prepare_enctype_priority_list(void)
 	sep = "";
 	gss_krb5_enctype_priority_list[0] = '\0';
 	for (total = 0, i = 0; i < ARRAY_SIZE(gss_krb5_enctypes); i++) {
+		if (!crypto_krb5_find_enctype(gss_krb5_enctypes[i]))
+			continue;
 		n = sprintf(buf, "%s%u", sep, gss_krb5_enctypes[i]);
 		if (n < 0)
 			break;

-- 
2.53.0