[PATCH v4 24/24] s390/pkey/crypto: Introduce xflags param for pkey in-kernel API

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

Add a new parameter xflags to the in-kernel API function
pkey_key2protkey(). Currently there is only one flag supported:

* PKEY_XFLAG_NOMEMALLOC:
  If this flag is given in the xflags parameter, the pkey
  implementation is not allowed to allocate memory but instead should
  fall back to use preallocated memory or simple fail with -ENOMEM.
  This flag is for protected key derive within a cipher or similar
  which must not allocate memory which would cause io operations - see
  also the CRYPTO_ALG_ALLOCATES_MEMORY flag in crypto.h.

The one and only user of this in-kernel API - the skcipher
implementations PAES in paes_s390.c set this flag upon request
to derive a protected key from the given raw key material.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
---
 arch/s390/crypto/paes_s390.c   |  6 +++---
 arch/s390/include/asm/pkey.h   | 15 ++++++++++++++-
 drivers/s390/crypto/pkey_api.c | 11 +++++++----
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/arch/s390/crypto/paes_s390.c b/arch/s390/crypto/paes_s390.c
index 511093713a6f..1f62a9460405 100644
--- a/arch/s390/crypto/paes_s390.c
+++ b/arch/s390/crypto/paes_s390.c
@@ -182,14 +182,14 @@ static inline int __paes_keyblob2pkey(const u8 *key, unsigned int keylen,
 {
 	int i, rc = -EIO;
 
-	/* try three times in case of busy card */
+	/* try three times in case of busy card or no mem */
 	for (i = 0; rc && i < 3; i++) {
-		if (rc == -EBUSY && in_task()) {
+		if ((rc == -EBUSY || rc == -ENOMEM) && in_task()) {
 			if (msleep_interruptible(1000))
 				return -EINTR;
 		}
 		rc = pkey_key2protkey(key, keylen, pk->protkey, &pk->len,
-				      &pk->type);
+				      &pk->type, PKEY_XFLAG_NOMEMALLOC);
 	}
 
 	return rc;
diff --git a/arch/s390/include/asm/pkey.h b/arch/s390/include/asm/pkey.h
index 5dca1a46a9f6..c0e7f8c25e9f 100644
--- a/arch/s390/include/asm/pkey.h
+++ b/arch/s390/include/asm/pkey.h
@@ -20,9 +20,22 @@
  * @param key pointer to a buffer containing the key blob
  * @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.
  * @return 0 on success, negative errno value on failure
  */
 int pkey_key2protkey(const u8 *key, u32 keylen,
-		     u8 *protkey, u32 *protkeylen, u32 *protkeytype);
+		     u8 *protkey, u32 *protkeylen, u32 *protkeytype,
+		     u32 xflags);
+
+/*
+ * If this flag is given in the xflags parameter, the pkey implementation
+ * is not allowed to allocate memory but instead should fall back to use
+ * preallocated memory or simple fail with -ENOMEM.
+ * This flag is for protected key derive within a cipher or similar
+ * which must not allocate memory which would cause io operations - see
+ * also the CRYPTO_ALG_ALLOCATES_MEMORY flag in crypto.h.
+ */
+#define PKEY_XFLAG_NOMEMALLOC 0x0001
 
 #endif /* _KAPI_PKEY_H */
diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index 55a4e70b866b..c46b57001550 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -53,17 +53,20 @@ static int key2protkey(const struct pkey_apqn *apqns, size_t nr_apqns,
  * In-Kernel function: Transform a key blob (of any type) into a protected key
  */
 int pkey_key2protkey(const u8 *key, u32 keylen,
-		     u8 *protkey, u32 *protkeylen, u32 *protkeytype)
+		     u8 *protkey, u32 *protkeylen, u32 *protkeytype, u32 xflags)
 {
+	u32 flags;
 	int rc;
-	const u32 xflags = 0;
+
+	/* as of now only the NOMEMALLOC flag is supported */
+	flags = xflags & PKEY_XFLAG_NOMEMALLOC ? ZCRYPT_XFLAG_NOMEMALLOC : 0;
 
 	rc = key2protkey(NULL, 0, key, keylen,
-			 protkey, protkeylen, protkeytype, xflags);
+			 protkey, protkeylen, protkeytype, flags);
 	if (rc == -ENODEV) {
 		pkey_handler_request_modules();
 		rc = key2protkey(NULL, 0, key, keylen,
-				 protkey, protkeylen, protkeytype, xflags);
+				 protkey, protkeylen, protkeytype, flags);
 	}
 
 	return rc;
-- 
2.43.0