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Message-ID: <CAFA6WYPyTAKr7G1RFtASkJf2qYRqMyHRcAphGn35ynQCyemQjQ@mail.gmail.com>
Date: Fri, 12 Apr 2024 12:35:56 +0530
From: Sumit Garg <sumit.garg@...aro.org>
To: Jens Wiklander <jens.wiklander@...aro.org>
Cc: linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
op-tee@...ts.trustedfirmware.org,
Shyam Saini <shyamsaini@...ux.microsoft.com>, Ulf Hansson <ulf.hansson@...aro.org>,
Linus Walleij <linus.walleij@...aro.org>, Jerome Forissier <jerome.forissier@...aro.org>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>, Bart Van Assche <bvanassche@....org>,
Randy Dunlap <rdunlap@...radead.org>, Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v4 3/3] optee: probe RPMB device using RPMB subsystem
On Thu, 11 Apr 2024 at 12:23, Jens Wiklander <jens.wiklander@...aro.org> wrote:
>
> Hi Sumit,
>
> On Wed, Apr 10, 2024 at 12:48 PM Sumit Garg <sumit.garg@...aro.org> wrote:
> >
> > Hi Jens,
> >
> > On Fri, 5 Apr 2024 at 17:23, Jens Wiklander <jens.wiklander@...aro.org> wrote:
> > >
> > > Adds support in the OP-TEE drivers (both SMC and FF-A ABIs) to probe and
> > > use an RPMB device via the RPBM subsystem instead of passing the RPMB
> >
> > s/RPBM/RPMB/
>
> Thanks, I'll fix it.
>
> >
> > > frames via tee-supplicant in user space. A fallback mechanism is kept to
> > > route RPMB frames via tee-supplicant if the RPMB subsystem isn't
> > > available.
> > >
> > > The OP-TEE RPC ABI is extended to support iterating over all RPMB
> > > devices until one is found with the expected RPMB key already
> > > programmed.
> > >
> > > Signed-off-by: Jens Wiklander <jens.wiklander@...aro.org>
> > > ---
> > > drivers/tee/optee/core.c | 30 ++++
> > > drivers/tee/optee/device.c | 7 +
> > > drivers/tee/optee/ffa_abi.c | 8 +
> > > drivers/tee/optee/optee_private.h | 21 ++-
> > > drivers/tee/optee/optee_rpc_cmd.h | 35 +++++
> > > drivers/tee/optee/rpc.c | 233 ++++++++++++++++++++++++++++++
> > > drivers/tee/optee/smc_abi.c | 7 +
> > > 7 files changed, 340 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> > > index 3aed554bc8d8..082691c10a90 100644
> > > --- a/drivers/tee/optee/core.c
> > > +++ b/drivers/tee/optee/core.c
> > > @@ -11,6 +11,7 @@
> > > #include <linux/io.h>
> > > #include <linux/mm.h>
> > > #include <linux/module.h>
> > > +#include <linux/rpmb.h>
> > > #include <linux/slab.h>
> > > #include <linux/string.h>
> > > #include <linux/tee_drv.h>
> > > @@ -80,6 +81,31 @@ void optee_pool_op_free_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> > > shm->pages = NULL;
> > > }
> > >
> > > +void optee_bus_scan_rpmb(struct work_struct *work)
> > > +{
> > > + struct optee *optee = container_of(work, struct optee,
> > > + rpmb_scan_bus_work);
> > > + int ret;
> > > +
> > > + if (!optee->rpmb_scan_bus_done) {
> > > + ret = optee_enumerate_devices(PTA_CMD_GET_DEVICES_RPMB);
> > > + optee->rpmb_scan_bus_done = !ret;
> > > + if (ret && ret != -ENODEV)
> > > + pr_info("Scanning for RPMB device: ret %d\n", ret);
> > > + }
> > > +}
> > > +
> > > +int optee_rpmb_intf_rdev(struct notifier_block *intf, unsigned long action,
> > > + void *data)
> > > +{
> > > + struct optee *optee = container_of(intf, struct optee, rpmb_intf);
> > > +
> > > + if (action == RPMB_NOTIFY_ADD_DEVICE)
> > > + schedule_work(&optee->rpmb_scan_bus_work);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > static void optee_bus_scan(struct work_struct *work)
> > > {
> > > WARN_ON(optee_enumerate_devices(PTA_CMD_GET_DEVICES_SUPP));
> > > @@ -161,6 +187,8 @@ void optee_release_supp(struct tee_context *ctx)
> > >
> > > void optee_remove_common(struct optee *optee)
> > > {
> > > + rpmb_interface_unregister(&optee->rpmb_intf);
> > > + cancel_work_sync(&optee->rpmb_scan_bus_work);
> > > /* Unregister OP-TEE specific client devices on TEE bus */
> > > optee_unregister_devices();
> > >
> > > @@ -177,6 +205,8 @@ void optee_remove_common(struct optee *optee)
> > > tee_shm_pool_free(optee->pool);
> > > optee_supp_uninit(&optee->supp);
> > > mutex_destroy(&optee->call_queue.mutex);
> > > + rpmb_dev_put(optee->rpmb_dev);
> > > + mutex_destroy(&optee->rpmb_dev_mutex);
> > > }
> > >
> > > static int smc_abi_rc;
> > > diff --git a/drivers/tee/optee/device.c b/drivers/tee/optee/device.c
> > > index 4b1092127694..4274876857c8 100644
> > > --- a/drivers/tee/optee/device.c
> > > +++ b/drivers/tee/optee/device.c
> > > @@ -43,6 +43,13 @@ static int get_devices(struct tee_context *ctx, u32 session,
> > > ret = tee_client_invoke_func(ctx, &inv_arg, param);
> > > if ((ret < 0) || ((inv_arg.ret != TEEC_SUCCESS) &&
> > > (inv_arg.ret != TEEC_ERROR_SHORT_BUFFER))) {
> > > + /*
> > > + * TEE_ERROR_STORAGE_NOT_AVAILABLE is returned when getting
> > > + * the list of device TAs that depends on RPMB but a usable
> > > + * RPMB device isn't found.
> > > + */
> > > + if (inv_arg.ret == TEE_ERROR_STORAGE_NOT_AVAILABLE)
> > > + return -ENODEV;
> > > pr_err("PTA_CMD_GET_DEVICES invoke function err: %x\n",
> > > inv_arg.ret);
> > > return -EINVAL;
> > > diff --git a/drivers/tee/optee/ffa_abi.c b/drivers/tee/optee/ffa_abi.c
> > > index ecb5eb079408..a8dfdb30b4e8 100644
> > > --- a/drivers/tee/optee/ffa_abi.c
> > > +++ b/drivers/tee/optee/ffa_abi.c
> > > @@ -7,6 +7,7 @@
> > >
> > > #include <linux/arm_ffa.h>
> > > #include <linux/errno.h>
> > > +#include <linux/rpmb.h>
> > > #include <linux/scatterlist.h>
> > > #include <linux/sched.h>
> > > #include <linux/slab.h>
> > > @@ -934,6 +935,7 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> > > optee_cq_init(&optee->call_queue, 0);
> > > optee_supp_init(&optee->supp);
> > > optee_shm_arg_cache_init(optee, arg_cache_flags);
> > > + mutex_init(&optee->rpmb_dev_mutex);
> > > ffa_dev_set_drvdata(ffa_dev, optee);
> > > ctx = teedev_open(optee->teedev);
> > > if (IS_ERR(ctx)) {
> > > @@ -955,6 +957,9 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> > > if (rc)
> > > goto err_unregister_devices;
> > >
> > > + INIT_WORK(&optee->rpmb_scan_bus_work, optee_bus_scan_rpmb);
> > > + optee->rpmb_intf.notifier_call = optee_rpmb_intf_rdev;
> > > + rpmb_interface_register(&optee->rpmb_intf);
> > > pr_info("initialized driver\n");
> > > return 0;
> > >
> > > @@ -968,6 +973,9 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
> > > teedev_close_context(ctx);
> > > err_rhashtable_free:
> > > rhashtable_free_and_destroy(&optee->ffa.global_ids, rh_free_fn, NULL);
> > > + rpmb_dev_put(optee->rpmb_dev);
> > > + mutex_destroy(&optee->rpmb_dev_mutex);
> > > + rpmb_interface_unregister(&optee->rpmb_intf);
> > > optee_supp_uninit(&optee->supp);
> > > mutex_destroy(&optee->call_queue.mutex);
> > > mutex_destroy(&optee->ffa.mutex);
> > > diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
> > > index 7a5243c78b55..ae72f3dda1d2 100644
> > > --- a/drivers/tee/optee/optee_private.h
> > > +++ b/drivers/tee/optee/optee_private.h
> > > @@ -8,6 +8,7 @@
> > >
> > > #include <linux/arm-smccc.h>
> > > #include <linux/rhashtable.h>
> > > +#include <linux/rpmb.h>
> > > #include <linux/semaphore.h>
> > > #include <linux/tee_drv.h>
> > > #include <linux/types.h>
> > > @@ -20,11 +21,13 @@
> > > /* Some Global Platform error codes used in this driver */
> > > #define TEEC_SUCCESS 0x00000000
> > > #define TEEC_ERROR_BAD_PARAMETERS 0xFFFF0006
> > > +#define TEEC_ERROR_ITEM_NOT_FOUND 0xFFFF0008
> > > #define TEEC_ERROR_NOT_SUPPORTED 0xFFFF000A
> > > #define TEEC_ERROR_COMMUNICATION 0xFFFF000E
> > > #define TEEC_ERROR_OUT_OF_MEMORY 0xFFFF000C
> > > #define TEEC_ERROR_BUSY 0xFFFF000D
> > > #define TEEC_ERROR_SHORT_BUFFER 0xFFFF0010
> > > +#define TEE_ERROR_STORAGE_NOT_AVAILABLE 0xF0100003
> > >
> > > #define TEEC_ORIGIN_COMMS 0x00000002
> > >
> > > @@ -197,6 +200,12 @@ struct optee_ops {
> > > * @notif: notification synchronization struct
> > > * @supp: supplicant synchronization struct for RPC to supplicant
> > > * @pool: shared memory pool
> > > + * @mutex: mutex protecting @rpmb_dev
> > > + * @rpmb_dev: current RPMB device or NULL
> > > + * @rpmb_scan_bus_done flag if device registation of RPMB dependent devices
> > > + * was already done
> > > + * @rpmb_scan_bus_work workq to for an RPMB device and to scan optee bus
> > > + * and register RPMB dependent optee drivers
> > > * @rpc_param_count: If > 0 number of RPC parameters to make room for
> > > * @scan_bus_done flag if device registation was already done.
> > > * @scan_bus_work workq to scan optee bus and register optee drivers
> > > @@ -215,9 +224,15 @@ struct optee {
> > > struct optee_notif notif;
> > > struct optee_supp supp;
> > > struct tee_shm_pool *pool;
> > > + /* Protects rpmb_dev pointer */
> > > + struct mutex rpmb_dev_mutex;
> > > + struct rpmb_dev *rpmb_dev;
> > > + struct notifier_block rpmb_intf;
> > > unsigned int rpc_param_count;
> > > - bool scan_bus_done;
> > > + bool scan_bus_done;
> > > + bool rpmb_scan_bus_done;
> > > struct work_struct scan_bus_work;
> > > + struct work_struct rpmb_scan_bus_work;
> > > };
> > >
> > > struct optee_session {
> > > @@ -280,8 +295,12 @@ int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session);
> > >
> > > #define PTA_CMD_GET_DEVICES 0x0
> > > #define PTA_CMD_GET_DEVICES_SUPP 0x1
> > > +#define PTA_CMD_GET_DEVICES_RPMB 0x2
> > > int optee_enumerate_devices(u32 func);
> > > void optee_unregister_devices(void);
> > > +void optee_bus_scan_rpmb(struct work_struct *work);
> > > +int optee_rpmb_intf_rdev(struct notifier_block *intf, unsigned long action,
> > > + void *data);
> > >
> > > int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
> > > size_t size, size_t align,
> > > diff --git a/drivers/tee/optee/optee_rpc_cmd.h b/drivers/tee/optee/optee_rpc_cmd.h
> > > index f3f06e0994a7..f351a8ac69fc 100644
> > > --- a/drivers/tee/optee/optee_rpc_cmd.h
> > > +++ b/drivers/tee/optee/optee_rpc_cmd.h
> > > @@ -16,6 +16,14 @@
> > > * and sends responses.
> > > */
> > >
> > > +/*
> > > + * Replay Protected Memory Block access
> > > + *
> > > + * [in] memref[0] Frames to device
> > > + * [out] memref[1] Frames from device
> > > + */
> > > +#define OPTEE_RPC_CMD_RPMB 1
> > > +
> > > /*
> > > * Get time
> > > *
> > > @@ -103,4 +111,31 @@
> > > /* I2C master control flags */
> > > #define OPTEE_RPC_I2C_FLAGS_TEN_BIT BIT(0)
> > >
> > > +/*
> > > + * Reset RPMB probing
> > > + *
> > > + * Releases an eventually already used RPMB devices and starts over searching
> > > + * for RPMB devices. Returns the kind of shared memory to use in subsequent
> > > + * OPTEE_RPC_CMD_RPMB_PROBE_NEXT and OPTEE_RPC_CMD_RPMB calls.
> > > + *
> > > + * [out] value[0].a OPTEE_RPC_SHM_TYPE_*, the parameter for
> > > + * OPTEE_RPC_CMD_SHM_ALLOC
> > > + */
> > > +#define OPTEE_RPC_CMD_RPMB_PROBE_RESET 22
> > > +
> >
> > AFAICS from [1], this RPMB reset probing is only used to check if the
> > kernel supports RPMB probing or not. I suppose that should be detected
> > via a single RPC call like: OPTEE_RPC_CMD_RPMB_PROBE. Other than that
> > the shared memory allocation type can be used as
> > THREAD_SHM_TYPE_KERNEL_PRIVATE if OPTEE_RPC_CMD_RPMB_PROBE works
> > otherwise THREAD_SHM_TYPE_APPLICATION can be used for legacy RPMB init
> > via tee-supplicant.
> >
> > Is there any other specific scenario I am missing which requires an
> > explicit RPMB probe reset call?
>
> That assumes that we're not going to implement
> OPTEE_RPC_CMD_RPMB_PROBE_RESET and OPTEE_RPC_CMD_RPMB_PROBE_NEXT in
> the tee-supplicant. We should implement those RPCs in the
> tee-supplicant too since it solves the problem with finding the RPMB
> device without device-specific runtime arguments for the
> tee-supplicant.
IMO, we should try to deprecate the tee-supplicant accesses to
hardware RPMB. The tee-supplicant can be useful for RPMB emulation
scenarios where we shouldn't require the dynamic discovery of RPMB.
>
> I'd also like to keep the ABI flexible so we for instance can handle a
> removable RPMB from the secure world.
That's an interesting scenario but I am not sure if we really would
like to deal with the complications of removable RPMB like what we
should do if a TA is accessing RPMB during which it is hot plugged?
However, I am in favour of an ABI which is simple enough to maintain
and allow flexibility for extension like adding a new RPC when it's
really needed etc.
-Sumit
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