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Subject[PATCH v5 2/2] tee: add private login method for kernel clients
Date
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 - 0xFFFFFFFF).

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
drivers/tee/tee_core.c | 6 ++++++
include/uapi/linux/tee.h | 8 ++++++++
2 files changed, 14 insertions(+)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 37d22e3..533e7a8 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
goto out;
}

+ if (arg.clnt_login & TEE_IOCTL_LOGIN_MASK) {
+ 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..19172a2 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -173,6 +173,14 @@ 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 - 0xFFFFFFFF). This range is rather
+ * being reserved for REE kernel clients or TEE implementation.
+ */
+#define TEE_IOCTL_LOGIN_MASK 0x80000000
+/* Private login method for REE kernel clients */
+#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000

/**
* struct tee_ioctl_param - parameter
--
2.7.4
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