s390/pkey: Introduce new API for random protected key generation
This patch introduces a new ioctl API and in-kernel API to
generate a random protected key. The protected key is generated
in a way that the effective clear key is never exposed in clear.
Both APIs are described in detail in the header files
arch/s390/include/asm/pkey.h and arch/s390/include/uapi/asm/pkey.h.
Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/pkey.h b/arch/s390/include/asm/pkey.h
index 053117b..c931818 100644
--- a/arch/s390/include/asm/pkey.h
+++ b/arch/s390/include/asm/pkey.h
@@ -109,4 +109,12 @@ int pkey_verifykey(const struct pkey_seckey *seckey,
u16 *pcardnr, u16 *pdomain,
u16 *pkeysize, u32 *pattributes);
+/*
+ * In-kernel API: Generate (AES) random protected key.
+ * @param keytype one of the PKEY_KEYTYPE values
+ * @param protkey pointer to buffer receiving the protected key
+ * @return 0 on success, negative errno value on failure
+ */
+int pkey_genprotkey(__u32 keytype, struct pkey_protkey *protkey);
+
#endif /* _KAPI_PKEY_H */
diff --git a/arch/s390/include/uapi/asm/pkey.h b/arch/s390/include/uapi/asm/pkey.h
index 6f84a53..10a7bc7 100644
--- a/arch/s390/include/uapi/asm/pkey.h
+++ b/arch/s390/include/uapi/asm/pkey.h
@@ -129,4 +129,14 @@ struct pkey_verifykey {
#define PKEY_VERIFY_ATTR_AES 0x00000001 /* key is an AES key */
#define PKEY_VERIFY_ATTR_OLD_MKVP 0x00000100 /* key has old MKVP value */
+/*
+ * Generate (AES) random protected key.
+ */
+struct pkey_genprotk {
+ __u32 keytype; /* in: key type to generate */
+ struct pkey_protkey protkey; /* out: the protected key */
+};
+
+#define PKEY_GENPROTK _IOWR(PKEY_IOCTL_MAGIC, 0x08, struct pkey_genprotk)
+
#endif /* _UAPI_PKEY_H */
diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index 1b4001e..29028ccd 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -16,6 +16,7 @@
#include <linux/slab.h>
#include <linux/kallsyms.h>
#include <linux/debugfs.h>
+#include <linux/random.h>
#include <asm/zcrypt.h>
#include <asm/cpacf.h>
#include <asm/pkey.h>
@@ -1052,6 +1053,46 @@ int pkey_verifykey(const struct pkey_seckey *seckey,
EXPORT_SYMBOL(pkey_verifykey);
/*
+ * Generate a random protected key
+ */
+int pkey_genprotkey(__u32 keytype, struct pkey_protkey *protkey)
+{
+ struct pkey_clrkey clrkey;
+ int keysize;
+ int rc;
+
+ switch (keytype) {
+ case PKEY_KEYTYPE_AES_128:
+ keysize = 16;
+ break;
+ case PKEY_KEYTYPE_AES_192:
+ keysize = 24;
+ break;
+ case PKEY_KEYTYPE_AES_256:
+ keysize = 32;
+ break;
+ default:
+ DEBUG_ERR("%s unknown/unsupported keytype %d\n", __func__,
+ keytype);
+ return -EINVAL;
+ }
+
+ /* generate a dummy random clear key */
+ get_random_bytes(clrkey.clrkey, keysize);
+
+ /* convert it to a dummy protected key */
+ rc = pkey_clr2protkey(keytype, &clrkey, protkey);
+ if (rc)
+ return rc;
+
+ /* replace the key part of the protected key with random bytes */
+ get_random_bytes(protkey->protkey, keysize);
+
+ return 0;
+}
+EXPORT_SYMBOL(pkey_genprotkey);
+
+/*
* File io functions
*/
@@ -1167,6 +1208,20 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
return -EFAULT;
break;
}
+ case PKEY_GENPROTK: {
+ struct pkey_genprotk __user *ugp = (void __user *) arg;
+ struct pkey_genprotk kgp;
+
+ if (copy_from_user(&kgp, ugp, sizeof(kgp)))
+ return -EFAULT;
+ rc = pkey_genprotkey(kgp.keytype, &kgp.protkey);
+ DEBUG_DBG("%s pkey_genprotkey()=%d\n", __func__, rc);
+ if (rc)
+ break;
+ if (copy_to_user(ugp, &kgp, sizeof(kgp)))
+ return -EFAULT;
+ break;
+ }
default:
/* unknown/unsupported ioctl cmd */
return -ENOTTY;