[PATCH v6 0/2] Enhance TEE kernel client interface

[PATCH v6 0/2] Enhance TEE kernel client interface

[Sumit Garg]

Earlier this patch-set was part of TEE Trusted keys patch-set [1]. But
since these are completely independent enhancements for TEE kernel
client interface which can be merged separately while TEE Trusted keys
discussions are ongoing.

Patch #1 enables support for registered kernel shared memory with TEE.

Patch #2 enables support for private kernel login method required for
cases like trusted keys where we don't wan't user-space to directly
access TEE service.

[1] https://lkml.org/lkml/2019/10/31/430

Changes in v6:
- Reserve only half of GP implementation defined range for kernel space.

Changes in v5:
- Misc. renaming of variables.

Sumit Garg (2):
  tee: enable support to register kernel memory
  tee: add private login method for kernel clients

 drivers/tee/tee_core.c   |  7 +++++++
 drivers/tee/tee_shm.c    | 28 +++++++++++++++++++++++++---
 include/linux/tee_drv.h  |  1 +
 include/uapi/linux/tee.h |  9 +++++++++
 4 files changed, 42 insertions(+), 3 deletions(-)

-- 
2.7.4

[PATCH v6 1/2] tee: enable support to register kernel memory

[Sumit Garg]

Enable support to register kernel memory reference with TEE. This change
will allow TEE bus drivers to register memory references.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 drivers/tee/tee_shm.c   | 28 +++++++++++++++++++++++++---
 include/linux/tee_drv.h |  1 +
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 937ac5a..a6c75a4 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -9,6 +9,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/tee_drv.h>
+#include <linux/uio.h>
 #include "tee_private.h"
 
 static void tee_shm_release(struct tee_shm *shm)
@@ -217,14 +218,15 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 				 size_t length, u32 flags)
 {
 	struct tee_device *teedev = ctx->teedev;
-	const u32 req_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
+	const u32 req_user_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
+	const u32 req_kernel_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
 	struct tee_shm *shm;
 	void *ret;
 	int rc;
 	int num_pages;
 	unsigned long start;
 
-	if (flags != req_flags)
+	if (flags != req_user_flags && flags != req_kernel_flags)
 		return ERR_PTR(-ENOTSUPP);
 
 	if (!tee_device_get(teedev))
@@ -259,7 +261,27 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 		goto err;
 	}
 
-	rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
+	if (flags & TEE_SHM_USER_MAPPED) {
+		rc = get_user_pages_fast(start, num_pages, FOLL_WRITE,
+					 shm->pages);
+	} else {
+		struct kvec *kiov;
+		int i;
+
+		kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
+		if (!kiov) {
+			ret = ERR_PTR(-ENOMEM);
+			goto err;
+		}
+
+		for (i = 0; i < num_pages; i++) {
+			kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
+			kiov[i].iov_len = PAGE_SIZE;
+		}
+
+		rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
+		kfree(kiov);
+	}
 	if (rc > 0)
 		shm->num_pages = rc;
 	if (rc != num_pages) {
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 7a03f68..dedf8fa 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -26,6 +26,7 @@
 #define TEE_SHM_REGISTER	BIT(3)  /* Memory registered in secure world */
 #define TEE_SHM_USER_MAPPED	BIT(4)  /* Memory mapped in user space */
 #define TEE_SHM_POOL		BIT(5)  /* Memory allocated from pool */
+#define TEE_SHM_KERNEL_MAPPED	BIT(6)  /* Memory mapped in kernel space */
 
 struct device;
 struct tee_device;
-- 
2.7.4

[PATCH v6 2/2] tee: add private login method for kernel clients

[Sumit Garg]

There are use-cases where user-space shouldn't be allowed to communicate
directly with a TEE device which is dedicated to provide a specific
service for a kernel client. So add a private login method for kernel
clients and disallow user-space to open-session using GP implementation
defined login method range: (0x80000000 - 0xBFFFFFFF).

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
 drivers/tee/tee_core.c   | 7 +++++++
 include/uapi/linux/tee.h | 9 +++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 37d22e3..13a016e 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -334,6 +334,13 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
 			goto out;
 	}
 
+	if (arg.clnt_login >= TEE_IOCTL_LOGIN_REE_KERNEL_MIN &&
+	    arg.clnt_login <= TEE_IOCTL_LOGIN_REE_KERNEL_MAX) {
+		pr_debug("login method not allowed for user-space client\n");
+		rc = -EPERM;
+		goto out;
+	}
+
 	rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
 	if (rc)
 		goto out;
diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
index 6596f3a..b619f37 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -173,6 +173,15 @@ struct tee_ioctl_buf_data {
 #define TEE_IOCTL_LOGIN_APPLICATION		4
 #define TEE_IOCTL_LOGIN_USER_APPLICATION	5
 #define TEE_IOCTL_LOGIN_GROUP_APPLICATION	6
+/*
+ * Disallow user-space to use GP implementation specific login
+ * method range (0x80000000 - 0xBFFFFFFF). This range is rather
+ * being reserved for REE kernel clients or TEE implementation.
+ */
+#define TEE_IOCTL_LOGIN_REE_KERNEL_MIN		0x80000000
+#define TEE_IOCTL_LOGIN_REE_KERNEL_MAX		0xBFFFFFFF
+/* Private login method for REE kernel clients */
+#define TEE_IOCTL_LOGIN_REE_KERNEL		0x80000000
 
 /**
  * struct tee_ioctl_param - parameter
-- 
2.7.4

Re: [PATCH v6 0/2] Enhance TEE kernel client interface

[Sumit Garg]

Hi Jens,

On Fri, 27 Mar 2020 at 11:00, Sumit Garg <sumit.garg@linaro.org> wrote:
>
> Earlier this patch-set was part of TEE Trusted keys patch-set [1]. But
> since these are completely independent enhancements for TEE kernel
> client interface which can be merged separately while TEE Trusted keys
> discussions are ongoing.
>
> Patch #1 enables support for registered kernel shared memory with TEE.
>
> Patch #2 enables support for private kernel login method required for
> cases like trusted keys where we don't wan't user-space to directly
> access TEE service.
>
> [1] https://lkml.org/lkml/2019/10/31/430
>
> Changes in v6:
> - Reserve only half of GP implementation defined range for kernel space.
>
> Changes in v5:
> - Misc. renaming of variables.
>
> Sumit Garg (2):
>   tee: enable support to register kernel memory
>   tee: add private login method for kernel clients
>

In case we don't have any further comments, would you like to pick up these?

-Sumit

>  drivers/tee/tee_core.c   |  7 +++++++
>  drivers/tee/tee_shm.c    | 28 +++++++++++++++++++++++++---
>  include/linux/tee_drv.h  |  1 +
>  include/uapi/linux/tee.h |  9 +++++++++
>  4 files changed, 42 insertions(+), 3 deletions(-)
>
> --
> 2.7.4
>

Re: [PATCH v6 0/2] Enhance TEE kernel client interface

[Jens Wiklander]

Hi Sumit,

On Fri, Apr 17, 2020 at 12:45 PM Sumit Garg <sumit.garg@linaro.org> wrote:
>
> Hi Jens,
>
> On Fri, 27 Mar 2020 at 11:00, Sumit Garg <sumit.garg@linaro.org> wrote:
> >
> > Earlier this patch-set was part of TEE Trusted keys patch-set [1]. But
> > since these are completely independent enhancements for TEE kernel
> > client interface which can be merged separately while TEE Trusted keys
> > discussions are ongoing.
> >
> > Patch #1 enables support for registered kernel shared memory with TEE.
> >
> > Patch #2 enables support for private kernel login method required for
> > cases like trusted keys where we don't wan't user-space to directly
> > access TEE service.
> >
> > [1] https://lkml.org/lkml/2019/10/31/430
> >
> > Changes in v6:
> > - Reserve only half of GP implementation defined range for kernel space.
> >
> > Changes in v5:
> > - Misc. renaming of variables.
> >
> > Sumit Garg (2):
> >   tee: enable support to register kernel memory
> >   tee: add private login method for kernel clients
> >
>
> In case we don't have any further comments, would you like to pick up these?

Thanks for the reminder. I'm picking this up.

Jerome, it's not too late to provide a tag if you like.

Cheers,
Jens

Re: [PATCH v6 2/2] tee: add private login method for kernel clients

[Jerome Forissier]

On 3/27/20 6:29 AM, Sumit Garg wrote:
> There are use-cases where user-space shouldn't be allowed to communicate
> directly with a TEE device which is dedicated to provide a specific
> service for a kernel client. So add a private login method for kernel
> clients and disallow user-space to open-session using GP implementation
> defined login method range: (0x80000000 - 0xBFFFFFFF).
> 
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
>  drivers/tee/tee_core.c   | 7 +++++++
>  include/uapi/linux/tee.h | 9 +++++++++
>  2 files changed, 16 insertions(+)

Reviewed-by: Jerome Forissier <jerome@forissier.org>

Thanks,
-- 
Jerome