[PATCH] driver: tee: Handle NULL pointer indication from client
From: Jens Wiklander
Date: Fri Jul 10 2020 - 06:18:42 EST
From: Cedric Neveux <cedric.neveux@xxxxxxx>
TEE Client introduce a new capability "TEE_GEN_CAP_MEMREF_NULL"
to handle the support of the shared memory buffer with a NULL pointer.
This capability depends on TEE Capabilities and driver support.
Driver and TEE exchange capabilities at driver initialization.
Signed-off-by: Michael Whitfield <michael.whitfield@xxxxxxx>
Signed-off-by: Cedric Neveux <cedric.neveux@xxxxxxx>
Reviewed-by: Joakim Bech <joakim.bech@xxxxxxxxxx>
Tested-by: Joakim Bech <joakim.bech@xxxxxxxxxx> (QEMU)
Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
---
drivers/tee/optee/core.c | 7 +++++
drivers/tee/optee/optee_smc.h | 3 +++
drivers/tee/tee_core.c | 49 ++++++++++++++++++++++-------------
include/linux/tee_drv.h | 3 +++
include/uapi/linux/tee.h | 13 ++++++++++
5 files changed, 57 insertions(+), 18 deletions(-)
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index 99698b8a3a74..8ef66e75b65e 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -215,6 +215,8 @@ static void optee_get_version(struct tee_device *teedev,
if (optee->sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
v.gen_caps |= TEE_GEN_CAP_REG_MEM;
+ if (optee->sec_caps & OPTEE_SMC_SEC_CAP_MEMREF_NULL)
+ v.gen_caps |= TEE_GEN_CAP_MEMREF_NULL;
*vers = v;
}
@@ -246,6 +248,11 @@ static int optee_open(struct tee_context *ctx)
mutex_init(&ctxdata->mutex);
INIT_LIST_HEAD(&ctxdata->sess_list);
+ if (optee->sec_caps & OPTEE_SMC_SEC_CAP_MEMREF_NULL)
+ ctx->cap_memref_null = true;
+ else
+ ctx->cap_memref_null = false;
+
ctx->data = ctxdata;
return 0;
}
diff --git a/drivers/tee/optee/optee_smc.h b/drivers/tee/optee/optee_smc.h
index c72122d9c997..777ad54d4c2c 100644
--- a/drivers/tee/optee/optee_smc.h
+++ b/drivers/tee/optee/optee_smc.h
@@ -215,6 +215,9 @@ struct optee_smc_get_shm_config_result {
*/
#define OPTEE_SMC_SEC_CAP_DYNAMIC_SHM BIT(2)
+/* Secure world supports Shared Memory with a NULL buffer reference */
+#define OPTEE_SMC_SEC_CAP_MEMREF_NULL BIT(4)
+
#define OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES 9
#define OPTEE_SMC_EXCHANGE_CAPABILITIES \
OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_EXCHANGE_CAPABILITIES)
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 64637e09a095..ce0f0309b6ac 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -383,25 +383,38 @@ static int params_from_user(struct tee_context *ctx, struct tee_param *params,
case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
/*
- * If we fail to get a pointer to a shared memory
- * object (and increase the ref count) from an
- * identifier we return an error. All pointers that
- * has been added in params have an increased ref
- * count. It's the callers responibility to do
- * tee_shm_put() on all resolved pointers.
+ * If a NULL pointer is passed to a TA in the TEE,
+ * the ip.c IOCTL parameters is set to TEE_MEMREF_NULL
+ * indicating a NULL memory reference.
*/
- shm = tee_shm_get_from_id(ctx, ip.c);
- if (IS_ERR(shm))
- return PTR_ERR(shm);
-
- /*
- * Ensure offset + size does not overflow offset
- * and does not overflow the size of the referred
- * shared memory object.
- */
- if ((ip.a + ip.b) < ip.a ||
- (ip.a + ip.b) > shm->size) {
- tee_shm_put(shm);
+ if (ip.c != TEE_MEMREF_NULL) {
+ /*
+ * If we fail to get a pointer to a shared
+ * memory object (and increase the ref count)
+ * from an identifier we return an error. All
+ * pointers that has been added in params have
+ * an increased ref count. It's the callers
+ * responibility to do tee_shm_put() on all
+ * resolved pointers.
+ */
+ shm = tee_shm_get_from_id(ctx, ip.c);
+ if (IS_ERR(shm))
+ return PTR_ERR(shm);
+
+ /*
+ * Ensure offset + size does not overflow
+ * offset and does not overflow the size of
+ * the referred shared memory object.
+ */
+ if ((ip.a + ip.b) < ip.a ||
+ (ip.a + ip.b) > shm->size) {
+ tee_shm_put(shm);
+ return -EINVAL;
+ }
+ } else if (ctx->cap_memref_null) {
+ /* Pass NULL pointer to OP-TEE */
+ shm = NULL;
+ } else {
return -EINVAL;
}
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index d074302989dd..cdd049a724b1 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -47,6 +47,8 @@ struct tee_shm_pool;
* and just return with an error code. It is needed for requests
* that arises from TEE based kernel drivers that should be
* non-blocking in nature.
+ * @cap_memref_null: flag indicating if the TEE Client support shared
+ * memory buffer with a NULL pointer.
*/
struct tee_context {
struct tee_device *teedev;
@@ -54,6 +56,7 @@ struct tee_context {
struct kref refcount;
bool releasing;
bool supp_nowait;
+ bool cap_memref_null;
};
struct tee_param_memref {
diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
index b619f37ee03e..d67cadf221fc 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -51,6 +51,9 @@
#define TEE_GEN_CAP_GP (1 << 0)/* GlobalPlatform compliant TEE */
#define TEE_GEN_CAP_PRIVILEGED (1 << 1)/* Privileged device (for supplicant) */
#define TEE_GEN_CAP_REG_MEM (1 << 2)/* Supports registering shared memory */
+#define TEE_GEN_CAP_MEMREF_NULL (1 << 3)/* NULL MemRef support */
+
+#define TEE_MEMREF_NULL (__u64)(-1) /* NULL MemRef Buffer */
/*
* TEE Implementation ID
@@ -200,6 +203,16 @@ struct tee_ioctl_buf_data {
* a part of a shared memory by specifying an offset (@a) and size (@b) of
* the object. To supply the entire shared memory object set the offset
* (@a) to 0 and size (@b) to the previously returned size of the object.
+ *
+ * A client may need to present a NULL pointer in the argument
+ * passed to a trusted application in the TEE.
+ * This is also a requirement in GlobalPlatform Client API v1.0c
+ * (section 3.2.5 memory references), which can be found at
+ * http://www.globalplatform.org/specificationsdevice.asp
+ *
+ * If a NULL pointer is passed to a TA in the TEE, the (@c)
+ * IOCTL parameters value must be set to TEE_MEMREF_NULL indicating a NULL
+ * memory reference.
*/
struct tee_ioctl_param {
__u64 attr;
--
2.25.1