On Mon, Jun 01, 2020 at 09:24:46AM +0200, Jorge Ramirez-Ortiz, Foundries wrote:
On 01/06/20, Sumit Garg wrote:
Hi Jorge,
hey
On Mon, 1 Jun 2020 at 04:41, Jorge Ramirez-Ortiz jorge@foundries.io wrote:
Some secure elements like NXP's SE050 sit on I2C buses. For OP-TEE to control this type of cryptographic devices it needs coordinated access to the bus, so collisions and RUNTIME_PM dont get in the way.
This trampoline driver allow OP-TEE to access them.
This sounds like an interesting use-case but I would like to understand how secure is this communication interface with the secure element? Like in the case of RPMB, secure world data is encrypted which flows via tee-supplicant to RPMB device.
right, the data in the buffer should be encrypted in both directions (in the case of the SE050 [1] we have the option to operate with or without encryption which is what I am doing during development [2]).
But ultimately -before any product can be shipped- all comms must be encrypted: this means that when OP-TEE uses the SE050 for crypto, it must encrypt the data on write and decrypt what is comming from the SE050 on read. I am now looking into how to enable this.
[1] https://www.nxp.com/docs/en/data-sheet/SE050-DATASHEET.pdf [2] https://github.com/ldts/optee_os/commits/se050
This link doesn't work.
-Sumit
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/optee_msg.h | 18 +++++++++++ drivers/tee/optee/rpc.c | 57 +++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+)
diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h index 795bc19ae17a..b6cc964fdeea 100644 --- a/drivers/tee/optee/optee_msg.h +++ b/drivers/tee/optee/optee_msg.h @@ -419,4 +419,22 @@ struct optee_msg_arg { */ #define OPTEE_MSG_RPC_CMD_SHM_FREE 7
+/*
- Access a device on an i2c bus
- [in] param[0].u.value.a mode: RD(0), WR(1)
- [in] param[0].u.value.b i2c adapter
- [in] param[0].u.value.c i2c chip
- [io] param[1].u.tmem.buf_ptr physical address
- [io] param[1].u.tmem.size transfer size in bytes
- [io] param[1].u.tmem.shm_ref shared memory reference
This should be "[in/out] memref[1]" instead to be able to use all kinds of memory references.
- [out] param[0].u.value.a bytes transferred
- */
+#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER 8 +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD 0 +#define OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR 1
#endif /* _OPTEE_MSG_H */ diff --git a/drivers/tee/optee/rpc.c b/drivers/tee/optee/rpc.c index b4ade54d1f28..21d452805c6f 100644 --- a/drivers/tee/optee/rpc.c +++ b/drivers/tee/optee/rpc.c @@ -9,6 +9,7 @@ #include <linux/device.h> #include <linux/slab.h> #include <linux/tee_drv.h> +#include <linux/i2c.h> #include "optee_private.h" #include "optee_smc.h"
@@ -48,6 +49,59 @@ static void handle_rpc_func_cmd_get_time(struct optee_msg_arg *arg) bad: arg->ret = TEEC_ERROR_BAD_PARAMETERS; } +static void handle_rpc_func_cmd_i2c_transfer(struct tee_context *ctx,
struct optee_msg_arg *arg)+{
struct i2c_client client;struct tee_shm *shm;int i, ret;char *buf;uint32_t attr[] = {OPTEE_MSG_ATTR_TYPE_VALUE_INPUT,OPTEE_MSG_ATTR_TYPE_TMEM_INOUT,OPTEE_MSG_ATTR_TYPE_VALUE_OUTPUT,};if (arg->num_params != ARRAY_SIZE(attr))goto bad;
Use optee_from_msg_param() to translate this into a struct tee_param, that way you cover all kinds of memory references. Before returning it nees to be translated back with optee_to_msg_param().
Cheers, Jens
for (i = 0; i < ARRAY_SIZE(attr); i++)if ((arg->params[i].attr & OPTEE_MSG_ATTR_TYPE_MASK) != attr[i])goto bad;shm = (struct tee_shm *)(unsigned long)arg->params[1].u.tmem.shm_ref;buf = (char *)shm->kaddr;client.addr = arg->params[0].u.value.c;client.adapter = i2c_get_adapter(arg->params[0].u.value.b);if (!client.adapter)goto bad;snprintf(client.name, I2C_NAME_SIZE, "i2c%d", client.adapter->nr);switch (arg->params[0].u.value.a) {case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_RD:ret = i2c_master_recv(&client, buf, arg->params[1].u.tmem.size);break;case OPTEE_MSG_RPC_CMD_I2C_TRANSFER_WR:ret = i2c_master_send(&client, buf, arg->params[1].u.tmem.size);break;default:i2c_put_adapter(client.adapter);goto bad;}if (ret >= 0) {arg->params[2].u.value.a = ret;arg->ret = TEEC_SUCCESS;} elsearg->ret = TEEC_ERROR_COMMUNICATION;i2c_put_adapter(client.adapter);return;+bad:
arg->ret = TEEC_ERROR_BAD_PARAMETERS;+}
static struct wq_entry *wq_entry_get(struct optee_wait_queue *wq, u32 key) { @@ -382,6 +436,9 @@ static void handle_rpc_func_cmd(struct tee_context *ctx, struct optee *optee, case OPTEE_MSG_RPC_CMD_SHM_FREE: handle_rpc_func_cmd_shm_free(ctx, arg); break;
case OPTEE_MSG_RPC_CMD_I2C_TRANSFER:handle_rpc_func_cmd_i2c_transfer(ctx, arg);break; default: handle_rpc_supp_cmd(ctx, arg); }-- 2.17.1
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