Adds utility function in TEE subsystem for client UUID generation. This

function is also used in the optee driver.
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Merge tag 'tee-login-for-5.8' of git://git.linaro.org/people/jens.wiklander/linux-tee into arm/drivers

Adds utility function in TEE subsystem for client UUID generation. This
function is also used in the optee driver.

* tag 'tee-login-for-5.8' of git://git.linaro.org/people/jens.wiklander/linux-tee:
  tee: optee: Add support for session login client UUID generation
  tee: add support for session's client UUID generation

Link: https://lore.kernel.org/r/20200512131243.GA10028@jade
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/tee/Kconfig

@@ -3,6 +3,7 @@
 config TEE
 	tristate "Trusted Execution Environment support"
 	depends on HAVE_ARM_SMCCC || COMPILE_TEST || CPU_SUP_AMD
+	select CRYPTO_SHA1
 	select DMA_SHARED_BUFFER
 	select GENERIC_ALLOCATOR
 	help

drivers/tee/optee/call.c

@@ -233,9 +233,13 @@ int optee_open_session(struct tee_context *ctx,
 	msg_arg->params[1].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT |
 				  OPTEE_MSG_ATTR_META;
 	memcpy(&msg_arg->params[0].u.value, arg->uuid, sizeof(arg->uuid));
-	memcpy(&msg_arg->params[1].u.value, arg->uuid, sizeof(arg->clnt_uuid));
 	msg_arg->params[1].u.value.c = arg->clnt_login;
 
+	rc = tee_session_calc_client_uuid((uuid_t *)&msg_arg->params[1].u.value,
+					  arg->clnt_login, arg->clnt_uuid);
+	if (rc)
+		goto out;
+
 	rc = optee_to_msg_param(msg_arg->params + 2, arg->num_params, param);
 	if (rc)
 		goto out;

drivers/tee/tee_core.c

@@ -6,18 +6,33 @@
 #define pr_fmt(fmt) "%s: " fmt, __func__
 
 #include <linux/cdev.h>
+#include <linux/cred.h>
 #include <linux/fs.h>
 #include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/tee_drv.h>
 #include <linux/uaccess.h>
+#include <crypto/hash.h>
+#include <crypto/sha.h>
 #include "tee_private.h"
 
 #define TEE_NUM_DEVICES	32
 
 #define TEE_IOCTL_PARAM_SIZE(x) (sizeof(struct tee_param) * (x))
 
+#define TEE_UUID_NS_NAME_SIZE	128
+
+/*
+ * TEE Client UUID name space identifier (UUIDv4)
+ *
+ * Value here is random UUID that is allocated as name space identifier for
+ * forming Client UUID's for TEE environment using UUIDv5 scheme.
+ */
+static const uuid_t tee_client_uuid_ns = UUID_INIT(0x58ac9ca0, 0x2086, 0x4683,
+						   0xa1, 0xb8, 0xec, 0x4b,
+						   0xc0, 0x8e, 0x01, 0xb6);
+
 /*
  * Unprivileged devices in the lower half range and privileged devices in
  * the upper half range.
@@ -110,6 +125,143 @@ static int tee_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+/**
+ * uuid_v5() - Calculate UUIDv5
+ * @uuid: Resulting UUID
+ * @ns: Name space ID for UUIDv5 function
+ * @name: Name for UUIDv5 function
+ * @size: Size of name
+ *
+ * UUIDv5 is specific in RFC 4122.
+ *
+ * This implements section (for SHA-1):
+ * 4.3.  Algorithm for Creating a Name-Based UUID
+ */
+static int uuid_v5(uuid_t *uuid, const uuid_t *ns, const void *name,
+		   size_t size)
+{
+	unsigned char hash[SHA1_DIGEST_SIZE];
+	struct crypto_shash *shash = NULL;
+	struct shash_desc *desc = NULL;
+	int rc;
+
+	shash = crypto_alloc_shash("sha1", 0, 0);
+	if (IS_ERR(shash)) {
+		rc = PTR_ERR(shash);
+		pr_err("shash(sha1) allocation failed\n");
+		return rc;
+	}
+
+	desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
+		       GFP_KERNEL);
+	if (!desc) {
+		rc = -ENOMEM;
+		goto out_free_shash;
+	}
+
+	desc->tfm = shash;
+
+	rc = crypto_shash_init(desc);
+	if (rc < 0)
+		goto out_free_desc;
+
+	rc = crypto_shash_update(desc, (const u8 *)ns, sizeof(*ns));
+	if (rc < 0)
+		goto out_free_desc;
+
+	rc = crypto_shash_update(desc, (const u8 *)name, size);
+	if (rc < 0)
+		goto out_free_desc;
+
+	rc = crypto_shash_final(desc, hash);
+	if (rc < 0)
+		goto out_free_desc;
+
+	memcpy(uuid->b, hash, UUID_SIZE);
+
+	/* Tag for version 5 */
+	uuid->b[6] = (hash[6] & 0x0F) | 0x50;
+	uuid->b[8] = (hash[8] & 0x3F) | 0x80;
+
+out_free_desc:
+	kfree(desc);
+
+out_free_shash:
+	crypto_free_shash(shash);
+	return rc;
+}
+
+int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method,
+				 const u8 connection_data[TEE_IOCTL_UUID_LEN])
+{
+	gid_t ns_grp = (gid_t)-1;
+	kgid_t grp = INVALID_GID;
+	char *name = NULL;
+	int name_len;
+	int rc;
+
+	if (connection_method == TEE_IOCTL_LOGIN_PUBLIC) {
+		/* Nil UUID to be passed to TEE environment */
+		uuid_copy(uuid, &uuid_null);
+		return 0;
+	}
+
+	/*
+	 * In Linux environment client UUID is based on UUIDv5.
+	 *
+	 * Determine client UUID with following semantics for 'name':
+	 *
+	 * For TEEC_LOGIN_USER:
+	 * uid=<uid>
+	 *
+	 * For TEEC_LOGIN_GROUP:
+	 * gid=<gid>
+	 *
+	 */
+
+	name = kzalloc(TEE_UUID_NS_NAME_SIZE, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	switch (connection_method) {
+	case TEE_IOCTL_LOGIN_USER:
+		name_len = snprintf(name, TEE_UUID_NS_NAME_SIZE, "uid=%x",
+				    current_euid().val);
+		if (name_len >= TEE_UUID_NS_NAME_SIZE) {
+			rc = -E2BIG;
+			goto out_free_name;
+		}
+		break;
+
+	case TEE_IOCTL_LOGIN_GROUP:
+		memcpy(&ns_grp, connection_data, sizeof(gid_t));
+		grp = make_kgid(current_user_ns(), ns_grp);
+		if (!gid_valid(grp) || !in_egroup_p(grp)) {
+			rc = -EPERM;
+			goto out_free_name;
+		}
+
+		name_len = snprintf(name, TEE_UUID_NS_NAME_SIZE, "gid=%x",
+				    grp.val);
+		if (name_len >= TEE_UUID_NS_NAME_SIZE) {
+			rc = -E2BIG;
+			goto out_free_name;
+		}
+		break;
+
+	default:
+		rc = -EINVAL;
+		goto out_free_name;
+	}
+
+	rc = uuid_v5(uuid, &tee_client_uuid_ns, name, name_len);
+out_free_name:
+	kfree(name);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tee_session_calc_client_uuid);
+
 static int tee_ioctl_version(struct tee_context *ctx,
 			     struct tee_ioctl_version_data __user *uvers)
 {

include/linux/tee_drv.h

@@ -166,6 +166,22 @@ int tee_device_register(struct tee_device *teedev);
  */
 void tee_device_unregister(struct tee_device *teedev);
 
+/**
+ * tee_session_calc_client_uuid() - Calculates client UUID for session
+ * @uuid:		Resulting UUID
+ * @connection_method:	Connection method for session (TEE_IOCTL_LOGIN_*)
+ * @connectuon_data:	Connection data for opening session
+ *
+ * Based on connection method calculates UUIDv5 based client UUID.
+ *
+ * For group based logins verifies that calling process has specified
+ * credentials.
+ *
+ * @return < 0 on failure
+ */
+int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method,
+				 const u8 connection_data[TEE_IOCTL_UUID_LEN]);
+
 /**
  * struct tee_shm - shared memory object
  * @ctx:	context using the object