[PATCH] crypto: caam: blob_gen.c: warn if key is insecure

[Nikolaus Voss]

If CAAM is not in "trusted" or "secure" state, a fixed non-volatile key
is used instead of the unique device key. This is the default mode of
operation without secure boot (HAB). In this scenario, CAAM encrypted
blobs should be used only for testing but not in a production
environment, so issue a warning.

Signed-off-by: Nikolaus Voss <nikolaus.voss@xxxxxxxxxxxxxxx>
---
 drivers/crypto/caam/blob_gen.c | 8 ++++++++
 drivers/crypto/caam/regs.h     | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/drivers/crypto/caam/blob_gen.c b/drivers/crypto/caam/blob_gen.c
index 6345c7269eb0..f3e741393f65 100644
--- a/drivers/crypto/caam/blob_gen.c
+++ b/drivers/crypto/caam/blob_gen.c
@@ -6,6 +6,7 @@
 
 #define pr_fmt(fmt) "caam blob_gen: " fmt
 
+#include <linux/bitfield.h>
 #include <linux/device.h>
 #include <soc/fsl/caam-blob.h>
 
@@ -62,11 +63,13 @@ int caam_process_blob(struct caam_blob_priv *priv,
 		      struct caam_blob_info *info, bool encap)
 {
 	struct caam_blob_job_result testres;
+	const struct caam_drv_private *ctrlpriv;
 	struct device *jrdev = &priv->jrdev;
 	dma_addr_t dma_in, dma_out;
 	int op = OP_PCLID_BLOB;
 	size_t output_len;
 	u32 *desc;
+	u32 moo;
 	int ret;
 
 	if (info->key_mod_len > CAAM_BLOB_KEYMOD_LENGTH)
@@ -100,6 +103,11 @@ int caam_process_blob(struct caam_blob_priv *priv,
 		goto out_unmap_in;
 	}
 
+	ctrlpriv = dev_get_drvdata(jrdev->parent);
+	moo = FIELD_GET(CSTA_MOO, ctrlpriv->ctrl->perfmon.status);
+	if (moo != CSTA_MOO_SECURE && moo != CSTA_MOO_TRUSTED)
+		dev_warn(jrdev, "using insecure test key!\n");
+
 	/*
 	 * A data blob is encrypted using a blob key (BK); a random number.
 	 * The BK is used as an AES-CCM key. The initial block (B0) and the
diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
index 66d6dad841bb..b7de5fb5e056 100644
--- a/drivers/crypto/caam/regs.h
+++ b/drivers/crypto/caam/regs.h
@@ -426,6 +426,9 @@ struct caam_perfmon {
 	u32 rsvd2;
 #define CSTA_PLEND		BIT(10)
 #define CSTA_ALT_PLEND		BIT(18)
+#define CSTA_MOO		GENMASK(9, 8)
+#define CSTA_MOO_SECURE	1
+#define CSTA_MOO_TRUSTED	3
 	u32 status;		/* CSTA - CAAM Status */
 	u64 rsvd3;
 
-- 
2.34.1