[RFC PATCH v2 1/4] firmware: qcom_scm: Add support for programming inline crypto keys

Eric Biggers
2020-03-04T06:50:15Z

Add support for the Inline Crypto Engine (ICE) key programming interface
that's needed for the ufs-qcom driver to use inline encryption on
Snapdragon SoCs. This interface consists of two SCM calls: one to
program a key into a keyslot, and one to invalidate a keyslot.

Although the UFS specification defines a standard way to do this, on
these SoCs the Linux kernel isn't permitted to access the needed crypto
configuration registers directly; these SCM calls must be used instead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
drivers/firmware/qcom_scm.c | 96 +++++++++++++++++++++++++++++++++++++
drivers/firmware/qcom_scm.h | 4 ++
include/linux/qcom_scm.h | 19 ++++++++
3 files changed, 119 insertions(+)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 059bb0fbae9e..7fb9f606250f 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -9,6 +9,7 @@
#include <linux/dma-direct.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>
+#include <linux/slab.h>
#include <linux/types.h>
#include <linux/qcom_scm.h>
#include <linux/of.h>
@@ -926,6 +927,101 @@ int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset, u32 size)
}
EXPORT_SYMBOL(qcom_scm_ocmem_unlock);

+/**
+ * qcom_scm_ice_available() - Is the ICE key programming interface available?
+ *
+ * Return: true iff the SCM calls wrapped by qcom_scm_ice_invalidate_key() and
+ * qcom_scm_ice_set_key() are available.
+ */
+bool qcom_scm_ice_available(void)
+{
+ return __qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_ES,
+ QCOM_SCM_ES_INVALIDATE_ICE_KEY) &&
+ __qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_ES,
+ QCOM_SCM_ES_CONFIG_SET_ICE_KEY);
+}
+EXPORT_SYMBOL(qcom_scm_ice_available);
+
+/**
+ * qcom_scm_ice_invalidate_key() - Invalidate an inline encryption key
+ * @index: the keyslot to invalidate
+ *
+ * The UFSHCI standard defines a standard way to do this, but it doesn't work on
+ * these SoCs; only this SCM call does.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_ice_invalidate_key(u32 index)
+{
+ struct qcom_scm_desc desc = {
+ .svc = QCOM_SCM_SVC_ES,
+ .cmd = QCOM_SCM_ES_INVALIDATE_ICE_KEY,
+ .arginfo = QCOM_SCM_ARGS(1),
+ .args[0] = index,
+ .owner = ARM_SMCCC_OWNER_SIP,
+ };
+
+ return qcom_scm_call(__scm->dev, &desc, NULL);
+}
+EXPORT_SYMBOL(qcom_scm_ice_invalidate_key);
+
+/**
+ * qcom_scm_ice_set_key() - Set an inline encryption key
+ * @index: the keyslot into which to set the key
+ * @key: the key to program
+ * @key_size: the size of the key in bytes
+ * @cipher: the encryption algorithm the key is for
+ * @data_unit_size: the encryption data unit size, i.e. the size of each
+ * individual plaintext and ciphertext. Given in 512-byte
+ * units, e.g. 1 = 512 bytes, 8 = 4096 bytes, etc.
+ *
+ * Program a key into a keyslot of Qualcomm ICE (Inline Crypto Engine), where it
+ * can then be used to encrypt/decrypt UFS I/O requests inline.
+ *
+ * The UFSHCI standard defines a standard way to do this, but it doesn't work on
+ * these SoCs; only this SCM call does.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+ enum qcom_scm_ice_cipher cipher, int data_unit_size)
+{
+ struct qcom_scm_desc desc = {
+ .svc = QCOM_SCM_SVC_ES,
+ .cmd = QCOM_SCM_ES_CONFIG_SET_ICE_KEY,
+ .arginfo = QCOM_SCM_ARGS(5, QCOM_SCM_VAL, QCOM_SCM_RW,
+ QCOM_SCM_VAL, QCOM_SCM_VAL,
+ QCOM_SCM_VAL),
+ .args[0] = index,
+ .args[2] = key_size,
+ .args[3] = cipher,
+ .args[4] = data_unit_size,
+ .owner = ARM_SMCCC_OWNER_SIP,
+ };
+ u8 *keybuf;
+ dma_addr_t key_phys;
+ int ret;
+
+ keybuf = kmemdup(key, key_size, GFP_KERNEL);
+ if (!keybuf)
+ return -ENOMEM;
+
+ key_phys = dma_map_single(__scm->dev, keybuf, key_size, DMA_TO_DEVICE);
+ if (dma_mapping_error(__scm->dev, key_phys)) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ desc.args[1] = key_phys;
+
+ ret = qcom_scm_call(__scm->dev, &desc, NULL);
+
+ dma_unmap_single(__scm->dev, key_phys, key_size, DMA_TO_DEVICE);
+out:
+ kzfree(keybuf);
+ return ret;
+}
+EXPORT_SYMBOL(qcom_scm_ice_set_key);
+
/**
* qcom_scm_hdcp_available() - Check if secure environment supports HDCP.
*
diff --git a/drivers/firmware/qcom_scm.h b/drivers/firmware/qcom_scm.h
index d9ed670da222..38ea614d29fe 100644
--- a/drivers/firmware/qcom_scm.h
+++ b/drivers/firmware/qcom_scm.h
@@ -103,6 +103,10 @@ extern int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
#define QCOM_SCM_OCMEM_LOCK_CMD 0x01
#define QCOM_SCM_OCMEM_UNLOCK_CMD 0x02

+#define QCOM_SCM_SVC_ES 0x10 /* Enterprise Security */
+#define QCOM_SCM_ES_INVALIDATE_ICE_KEY 0x03
+#define QCOM_SCM_ES_CONFIG_SET_ICE_KEY 0x04
+
#define QCOM_SCM_SVC_HDCP 0x11
#define QCOM_SCM_HDCP_INVOKE 0x01

diff --git a/include/linux/qcom_scm.h b/include/linux/qcom_scm.h
index 3d6a24697761..8ca90f192aeb 100644
--- a/include/linux/qcom_scm.h
+++ b/include/linux/qcom_scm.h
@@ -44,6 +44,13 @@ enum qcom_scm_sec_dev_id {
QCOM_SCM_ICE_DEV_ID = 20,
};

+enum qcom_scm_ice_cipher {
+ QCOM_SCM_ICE_CIPHER_AES_128_XTS = 0,
+ QCOM_SCM_ICE_CIPHER_AES_128_CBC = 1,
+ QCOM_SCM_ICE_CIPHER_AES_256_XTS = 3,
+ QCOM_SCM_ICE_CIPHER_AES_256_CBC = 4,
+};
+
#define QCOM_SCM_VMID_HLOS 0x3
#define QCOM_SCM_VMID_MSS_MSA 0xF
#define QCOM_SCM_VMID_WLAN 0x18
@@ -88,6 +95,12 @@ extern int qcom_scm_ocmem_lock(enum qcom_scm_ocmem_client id, u32 offset,
extern int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id, u32 offset,
u32 size);

+extern bool qcom_scm_ice_available(void);
+extern int qcom_scm_ice_invalidate_key(u32 index);
+extern int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+ enum qcom_scm_ice_cipher cipher,
+ int data_unit_size);
+
extern bool qcom_scm_hdcp_available(void);
extern int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt,
u32 *resp);
@@ -138,6 +151,12 @@ static inline int qcom_scm_ocmem_lock(enum qcom_scm_ocmem_client id, u32 offset,
static inline int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id,
u32 offset, u32 size) { return -ENODEV; }

+static inline bool qcom_scm_ice_available(void) { return false; }
+static inline int qcom_scm_ice_invalidate_key(u32 index) { return -ENODEV; }
+static inline int qcom_scm_ice_set_key(u32 index, const u8 *key, int key_size,
+ enum qcom_scm_ice_cipher cipher,
+ int data_unit_size) { return -ENODEV; }
+
static inline bool qcom_scm_hdcp_available(void) { return false; }
static inline int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt,
u32 *resp) { return -ENODEV; }
--
2.25.1