Storage encryption has two IOCTLs for creating, importing
and preparing keys for encryption. For wrapped keys, these
IOCTLs need to interface with the secure environment, which
require these SCM calls.
generate_key: This is used to generate and return a longterm
wrapped key. Trustzone achieves this by generating
a key and then wrapping it using hwkm, returning
a wrapped keyblob.
import_key: The functionality is similar to generate, but here,
a raw key is imported into hwkm and a longterm wrapped
keyblob is returned.
prepare_key: The longterm wrapped key from import or generate
is made further secure by rewrapping it with a per-boot
ephemeral wrapped key before installing it to the linux
kernel for programming to ICE.
Signed-off-by: Gaurav Kashyap <quic_gaurkash@xxxxxxxxxxx>
---
drivers/firmware/qcom_scm.c | 222 +++++++++++++++++++++++++
drivers/firmware/qcom_scm.h | 3 +
include/linux/firmware/qcom/qcom_scm.h | 10 ++
3 files changed, 235 insertions(+)
diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 51062d5c7f7b..44dd1857747b 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -1210,6 +1210,228 @@ int qcom_scm_derive_sw_secret(const u8 *wrapped_key, u32 wrapped_key_size,
}
EXPORT_SYMBOL(qcom_scm_derive_sw_secret);
+/**
+ * qcom_scm_generate_ice_key() - Generate a wrapped key for encryption.
+ * @longterm_wrapped_key: the wrapped key returned after key generation
+ * @longterm_wrapped_key_size: size of the wrapped key to be returned.
+ *
+ * Qualcomm wrapped keys need to be generated in a trusted environment.
+ * A generate key IOCTL call is used to achieve this. These are longterm
+ * in nature as they need to be generated and wrapped only once per
+ * requirement.
+ *
+ * This SCM calls adds support for the generate key IOCTL to interface
+ * with the secure environment to generate and return a wrapped key..
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_generate_ice_key(u8 *longterm_wrapped_key,
+ u32 longterm_wrapped_key_size)
+{
+ struct qcom_scm_desc desc = {
+ .svc = QCOM_SCM_SVC_ES,
+ .cmd = QCOM_SCM_ES_GENERATE_ICE_KEY,
+ .arginfo = QCOM_SCM_ARGS(2, QCOM_SCM_RW,
+ QCOM_SCM_VAL),
+ .args[1] = longterm_wrapped_key_size,
+ .owner = ARM_SMCCC_OWNER_SIP,
+ };
+
+ void *longterm_wrapped_keybuf;
+ dma_addr_t longterm_wrapped_key_phys;
+ int ret;
+
+ /*
+ * Like qcom_scm_ice_set_key(), we use dma_alloc_coherent() to properly
+ * get a physical address, while guaranteeing that we can zeroize the
+ * key material later using memzero_explicit().
+ *
+ */
+ longterm_wrapped_keybuf = dma_alloc_coherent(__scm->dev,
+ longterm_wrapped_key_size,
+ &longterm_wrapped_key_phys, GFP_KERNEL);
+ if (!longterm_wrapped_keybuf)
+ return -ENOMEM;
+
+ desc.args[0] = longterm_wrapped_key_phys;
+
+ ret = qcom_scm_call(__scm->dev, &desc, NULL);
+ memcpy(longterm_wrapped_key, longterm_wrapped_keybuf,
+ longterm_wrapped_key_size);
+
+ memzero_explicit(longterm_wrapped_keybuf, longterm_wrapped_key_size);
+ dma_free_coherent(__scm->dev, longterm_wrapped_key_size,
+ longterm_wrapped_keybuf, longterm_wrapped_key_phys);
+
+ if (!ret)
+ return longterm_wrapped_key_size;
+
+ return ret;
+}
+EXPORT_SYMBOL(qcom_scm_generate_ice_key);
+
+/**
+ * qcom_scm_prepare_ice_key() - Get per boot ephemeral wrapped key
+ * @longterm_wrapped_key: the wrapped key
+ * @longterm_wrapped_key_size: size of the wrapped key
+ * @ephemeral_wrapped_key: ephemeral wrapped key to be returned
+ * @ephemeral_wrapped_key_size: size of the ephemeral wrapped key
+ *
+ * Qualcomm wrapped keys (longterm keys) are rewrapped with a per-boot
+ * ephemeral key for added protection. These are ephemeral in nature as
+ * they are valid only for that boot. A create key IOCTL is used to
+ * achieve this. These are the keys that are installed into the kernel
+ * to be then unwrapped and programmed into ICE.
+ *
+ * This SCM call adds support for the create key IOCTL to interface
+ * with the secure environment to rewrap the wrapped key with an
+ * ephemeral wrapping key.
+ *
+ * Return: 0 on success; -errno on failure.
+ */
+int qcom_scm_prepare_ice_key(const u8 *longterm_wrapped_key,
+ u32 longterm_wrapped_key_size,
+ u8 *ephemeral_wrapped_key,
+ u32 ephemeral_wrapped_key_size)
+{
+ struct qcom_scm_desc desc = {
+ .svc = QCOM_SCM_SVC_ES,
+ .cmd = QCOM_SCM_ES_PREPARE_ICE_KEY,
+ .arginfo = QCOM_SCM_ARGS(4, QCOM_SCM_RO,
+ QCOM_SCM_VAL, QCOM_SCM_RW,
+ QCOM_SCM_VAL),
+ .args[1] = longterm_wrapped_key_size,
+ .args[3] = ephemeral_wrapped_key_size,
+ .owner = ARM_SMCCC_OWNER_SIP,
+ };
+
+ void *longterm_wrapped_keybuf, *ephemeral_wrapped_keybuf;
+ dma_addr_t longterm_wrapped_key_phys, ephemeral_wrapped_key_phys;
+ int ret;
+
+ /*
+ * Like qcom_scm_ice_set_key(), we use dma_alloc_coherent() to properly
+ * get a physical address, while guaranteeing that we can zeroize the
+ * key material later using memzero_explicit().
+ *
+ */
+ longterm_wrapped_keybuf = dma_alloc_coherent(__scm->dev,
+ longterm_wrapped_key_size,
+ &longterm_wrapped_key_phys, GFP_KERNEL);
+ if (!longterm_wrapped_keybuf)
+ return -ENOMEM;
+ ephemeral_wrapped_keybuf = dma_alloc_coherent(__scm->dev,
+ ephemeral_wrapped_key_size,
+ &ephemeral_wrapped_key_phys, GFP_KERNEL);
+ if (!ephemeral_wrapped_keybuf) {
+ ret = -ENOMEM;
+ goto bail_keybuf;
+ }
+
+ memcpy(longterm_wrapped_keybuf, longterm_wrapped_key,
+ longterm_wrapped_key_size);
+ desc.args[0] = longterm_wrapped_key_phys;
+ desc.args[2] = ephemeral_wrapped_key_phys;
+
+ ret = qcom_scm_call(__scm->dev, &desc, NULL);
+ if (!ret)
+ memcpy(ephemeral_wrapped_key, ephemeral_wrapped_keybuf,
+ ephemeral_wrapped_key_size);
+
+ memzero_explicit(ephemeral_wrapped_keybuf, ephemeral_wrapped_key_size);
+ dma_free_coherent(__scm->dev, ephemeral_wrapped_key_size,
+ ephemeral_wrapped_keybuf,
+ ephemeral_wrapped_key_phys);
+
+bail_keybuf:
+ memzero_explicit(longterm_wrapped_keybuf, longterm_wrapped_key_size);
+ dma_free_coherent(__scm->dev, longterm_wrapped_key_size,
+ longterm_wrapped_keybuf, longterm_wrapped_key_phys);
+
+ if (!ret)
+ return ephemeral_wrapped_key_size;
+
+ return ret;
+}
+EXPORT_SYMBOL(qcom_scm_prepare_ice_key);
