From: Cedric Neveux cedric.neveux@nxp.com

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@nxp.com Signed-off-by: Cedric Neveux cedric.neveux@nxp.com Reviewed-by: Joakim Bech joakim.bech@linaro.org Tested-by: Joakim Bech joakim.bech@linaro.org (QEMU) Signed-off-by: Jens Wiklander jens.wiklander@linaro.org --- 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;