[PATCH v2 2/4] s390/pkey: Support new xflag PKEY_XFLAG_NOCLEARKEY

[Harald Freudenberger <freude@linux.ibm.com>]

Introduce a new xflag PKEY_XFLAG_NOCLEARKEY which when given refuses
the conversion of "clear key tokens" to protected key material.

Some algorithms (PAES, PHMAC) have the need to construct "clear key
tokens" to be used during selftest. But in general these algorithms
should only support clear key material for testing purpose. So now the
algorithm implementation can signal via xflag PKEY_XFLAG_NOCLEARKEY
that a conversion of clear key material to protected key is not
acceptable and thus the pkey layer (usually one of the handler
modules) refuses clear key material with -EINVAL.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
---
 arch/s390/include/asm/pkey.h     |  8 +++++++-
 drivers/s390/crypto/pkey_cca.c   |  5 +++++
 drivers/s390/crypto/pkey_ep11.c  |  5 +++++
 drivers/s390/crypto/pkey_pckmo.c | 12 +++++++++---
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/pkey.h b/arch/s390/include/asm/pkey.h
index b7b59faf16f4..0af5ac4f646b 100644
--- a/arch/s390/include/asm/pkey.h
+++ b/arch/s390/include/asm/pkey.h
@@ -21,7 +21,8 @@
  * @param keylen size of the key blob in bytes
  * @param protkey pointer to buffer receiving the protected key
  * @param xflags additional execution flags (see PKEY_XFLAG_* definitions below)
- *	  As of now the only supported flag is PKEY_XFLAG_NOMEMALLOC.
+ *	  As of now the only supported flags are PKEY_XFLAG_NOMEMALLOC
+ *	  and PKEY_XFLAG_NOCLEARKEY.
  * @return 0 on success, negative errno value on failure
  */
 int pkey_key2protkey(const u8 *key, u32 keylen,
@@ -38,4 +39,9 @@ int pkey_key2protkey(const u8 *key, u32 keylen,
  */
 #define PKEY_XFLAG_NOMEMALLOC 0x0001
 
+/*
+ * Do not accept a clear key token as source for a protected key.
+ */
+#define PKEY_XFLAG_NOCLEARKEY 0x0002
+
 #endif /* _KAPI_PKEY_H */
diff --git a/drivers/s390/crypto/pkey_cca.c b/drivers/s390/crypto/pkey_cca.c
index d4550d8d8eea..9bfb518db893 100644
--- a/drivers/s390/crypto/pkey_cca.c
+++ b/drivers/s390/crypto/pkey_cca.c
@@ -390,6 +390,11 @@ static int cca_clr2key(const struct pkey_apqn *apqns, size_t nr_apqns,
 	int i, len, rc;
 	u32 xflags;
 
+	if (pflags & PKEY_XFLAG_NOCLEARKEY) {
+		PKEY_DBF_ERR("%s clear key but xflag NOCLEARKEY\n", __func__);
+		return -EINVAL;
+	}
+
 	xflags = pflags & PKEY_XFLAG_NOMEMALLOC ? ZCRYPT_XFLAG_NOMEMALLOC : 0;
 
 	/* check keytype, subtype, clrkeylen, keybitsize */
diff --git a/drivers/s390/crypto/pkey_ep11.c b/drivers/s390/crypto/pkey_ep11.c
index 654eed20d0d9..f99c19323f3d 100644
--- a/drivers/s390/crypto/pkey_ep11.c
+++ b/drivers/s390/crypto/pkey_ep11.c
@@ -358,6 +358,11 @@ static int ep11_clr2key(const struct pkey_apqn *apqns, size_t nr_apqns,
 	int i, len, rc;
 	u32 xflags;
 
+	if (pflags & PKEY_XFLAG_NOCLEARKEY) {
+		PKEY_DBF_ERR("%s clear key but xflag NOCLEARKEY\n", __func__);
+		return -EINVAL;
+	}
+
 	xflags = pflags & PKEY_XFLAG_NOMEMALLOC ? ZCRYPT_XFLAG_NOMEMALLOC : 0;
 
 	/* check keytype, subtype, clrkeylen, keybitsize */
diff --git a/drivers/s390/crypto/pkey_pckmo.c b/drivers/s390/crypto/pkey_pckmo.c
index 793326c4c59a..ea774ab89180 100644
--- a/drivers/s390/crypto/pkey_pckmo.c
+++ b/drivers/s390/crypto/pkey_pckmo.c
@@ -215,7 +215,8 @@ static int pckmo_verify_protkey(const u8 *protkey, u32 protkeylen,
 }
 
 static int pckmo_key2protkey(const u8 *key, u32 keylen,
-			     u8 *protkey, u32 *protkeylen, u32 *protkeytype)
+			     u8 *protkey, u32 *protkeylen, u32 *protkeytype,
+			     u32 xflags)
 {
 	struct keytoken_header *hdr = (struct keytoken_header *)key;
 	int rc = -EINVAL;
@@ -266,6 +267,11 @@ static int pckmo_key2protkey(const u8 *key, u32 keylen,
 		struct clearkeytoken *t = (struct clearkeytoken *)key;
 		u32 keysize;
 
+		if (xflags & PKEY_XFLAG_NOCLEARKEY) {
+			PKEY_DBF_ERR("%s clear key token but xflag NOCLEARKEY\n",
+				     __func__);
+			goto out;
+		}
 		if (keylen < sizeof(*t) ||
 		    keylen < sizeof(*t) + t->len)
 			goto out;
@@ -406,10 +412,10 @@ static int pkey_pckmo_key2protkey(const struct pkey_apqn *_apqns,
 				  size_t _nr_apqns,
 				  const u8 *key, u32 keylen,
 				  u8 *protkey, u32 *protkeylen, u32 *keyinfo,
-				  u32 _xflags __always_unused)
+				  u32 xflags)
 {
 	return pckmo_key2protkey(key, keylen,
-				 protkey, protkeylen, keyinfo);
+				 protkey, protkeylen, keyinfo, xflags);
 }
 
 static int pkey_pckmo_gen_key(const struct pkey_apqn *_apqns, size_t _nr_apqns,
-- 
2.43.0