tee-supplicant: Allow for TA load path to be specified at runtime

Add a new `--ta-path` CLI flag for overriding the default load path used
by tee-supplicant. The given path string can be a set of colon (':')
separated paths, each being a full path used when searching for TAs.
When this option is not used, the existing behavior of loading TAs from
a subdirectory "ta-dir" under TEEC_LOAD_PATH is retained.

Signed-off-by: Jared Baur <jaredbaur@fastmail.com>
Reviewed-by: Etienne Carriere <etienne.carriere@foss.st.com>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>

tee-supplicant/src/tee_supplicant.c

@@ -64,11 +64,12 @@
 
 #define RPC_NUM_PARAMS	5
 
+#define DEFAULT_TA_DIR "optee_armtz"
+
 #define RPC_BUF_SIZE	(sizeof(struct tee_iocl_supp_send_arg) + \
 			 RPC_NUM_PARAMS * sizeof(struct tee_ioctl_param))
 
 char **ta_path;
-char *ta_path_str;
 
 union tee_rpc_invoke {
 	uint64_t buf[(RPC_BUF_SIZE - 1) / sizeof(uint64_t) + 1];
@@ -103,7 +104,6 @@ static pthread_mutex_t shm_mutex = PTHREAD_MUTEX_INITIALIZER;
 static struct tee_shm *shm_head;
 
 struct tee_supplicant_params supplicant_params = {
-	.ta_dir = "optee_armtz",
 #ifdef TEE_PLUGIN_LOAD_PATH
 	.plugin_load_path = TEE_PLUGIN_LOAD_PATH,
 #endif
@@ -300,7 +300,7 @@ static uint32_t load_ta(size_t num_params, struct tee_ioctl_param *params)
 	uuid_from_octets(&uuid, (void *)val_cmd);
 
 	size = shm_ta.size;
-	ta_found = TEECI_LoadSecureModule(supplicant_params.ta_dir, &uuid, shm_ta.buffer, &size);
+	ta_found = TEECI_LoadSecureModule(&uuid, shm_ta.buffer, &size);
 	if (ta_found != TA_BINARY_FOUND) {
 		EMSG("  TA not found");
 		return TEEC_ERROR_ITEM_NOT_FOUND;
@@ -495,8 +495,10 @@ static int usage(int status)
 			"after child has opened the TEE device or on error)\n");
 	fprintf(stderr, "\t-f, --fs-parent-path: secure fs parent path [%s]\n",
 			supplicant_params.fs_parent_path);
-	fprintf(stderr, "\t-t, --ta-dir: TAs dirname under %s [%s]\n", TEEC_LOAD_PATH,
-			supplicant_params.ta_dir);
+	fprintf(stderr, "\t-l, --ta-path: TA load path\n");
+	fprintf(stderr, "\t-t, --ta-dir: TAs dirname under %s [%s]"
+			" (deprecated, cannot be used with --ta-path)\n",
+			TEEC_LOAD_PATH, DEFAULT_TA_DIR);
 	fprintf(stderr, "\t-p, --plugin-path: plugin load path [%s]\n",
 			supplicant_params.plugin_load_path);
 	fprintf(stderr, "\t-r, --rpmb-cid: RPMB device identification register "
@@ -698,10 +700,15 @@ static void *thread_main(void *a)
 
 static void set_ta_path(void)
 {
+	char *ta_path_str = NULL;
 	char *p = NULL;
 	char *saveptr = NULL;
-	const char *path = (char *)TEEC_LOAD_PATH;
+	char *new_path = NULL;
 	size_t n = 0;
+	const char *path = supplicant_params.ta_load_path;
+
+	if (!path)
+		path = TEEC_LOAD_PATH;
 
 	ta_path_str = strdup(path);
 	if (!ta_path_str)
@@ -721,8 +728,22 @@ static void set_ta_path(void)
 	n = 0;
 	strcpy(ta_path_str, path);
 	p = ta_path_str;
-	while ((ta_path[n++] = strtok_r(p, ":", &saveptr)))
-	       p = NULL;
+
+	while ((new_path = strtok_r(p, ":", &saveptr))) {
+		if (!supplicant_params.ta_load_path) {
+			char full_path[PATH_MAX] = { 0 };
+
+			snprintf(full_path, PATH_MAX, "%s/%s", new_path,
+					supplicant_params.ta_dir);
+			ta_path[n++] = strdup(full_path);
+		} else {
+			ta_path[n++] = strdup(new_path);
+		}
+
+		p = NULL;
+	}
+
+	free(ta_path_str);
 
 	return;
 err:
@@ -803,13 +824,14 @@ int main(int argc, char *argv[])
 		{ "help",            no_argument,       0, 'h' },
 		{ "daemonize",       no_argument,       0, 'd' },
 		{ "fs-parent-path",  required_argument, 0, 'f' },
+		{ "ta-path",         required_argument, 0, 'l' },
 		{ "ta-dir",          required_argument, 0, 't' },
 		{ "plugin-path",     required_argument, 0, 'p' },
 		{ "rpmb-cid",        required_argument, 0, 'r' },
 		{ 0, 0, 0, 0 }
 	};
 
-	while ((opt = getopt_long(argc, argv, "hdf:t:p:r:",
+	while ((opt = getopt_long(argc, argv, "hdf:l:t:p:r:",
 				long_options, &long_index )) != -1) {
 		switch (opt) {
 			case 'h' :
@@ -821,6 +843,9 @@ int main(int argc, char *argv[])
 			case 'f':
 				supplicant_params.fs_parent_path = optarg;
 				break;
+			case 'l':
+				supplicant_params.ta_load_path = optarg;
+				break;
 			case 't':
 				supplicant_params.ta_dir = optarg;
 				break;
@@ -846,6 +871,12 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if (!supplicant_params.ta_dir && !supplicant_params.ta_load_path) {
+		supplicant_params.ta_dir = DEFAULT_TA_DIR;
+	} else if (supplicant_params.ta_dir && supplicant_params.ta_load_path) {
+		fprintf(stderr, "Cannot use --ta-path and --ta-dir at the same time\n");
+		return usage(EXIT_FAILURE);
+	}
 
 	set_ta_path();
 

tee-supplicant/src/tee_supplicant.h

@@ -41,6 +41,7 @@ struct tee_ioctl_param;
 /* Global tee-supplicant parameters */
 struct tee_supplicant_params {
     const char *ta_dir;
+    const char *ta_load_path;
     const char *plugin_load_path;
     const char *fs_parent_path;
     const char *rpmb_cid;

tee-supplicant/src/teec_ta_load.c

@@ -51,9 +51,8 @@ struct tee_rpc_cmd {
  * Based on the uuid this function will try to find a TA-binary on the
  * filesystem and return it back to the caller in the parameter ta.
  *
- * @param: prefix       Prefix for TA load path
- * @param: dev_path     Where to load the TA from. The full path to the TA
- *                      binary is @prefix/@dev_path/@destination.ta.
+ * @param: ta_load_path Where to load the TA from. The full path to the TA
+ *                      binary is @ta_load_path/@destination.ta.
  * @param: destination  The uuid of the TA we are searching for.
  * @param: ta           A pointer which this function will allocate and copy
  *                      the TA from the filesystem to the pointer itself. It is
@@ -63,8 +62,7 @@ struct tee_rpc_cmd {
  *
  * @return              0 if TA was found, otherwise -1.
  */
-static int try_load_secure_module(const char* prefix,
-				  const char* dev_path,
+static int try_load_secure_module(const char *ta_load_path,
 				  const TEEC_UUID *destination, void *ta,
 				  size_t *ta_size)
 {
@@ -88,8 +86,8 @@ static int try_load_secure_module(const char* prefix,
 	 */
 again:
 	n = snprintf(fname, PATH_MAX,
-		     "%s/%s/%08x-%04x-%04x-%02x%02x%s%02x%02x%02x%02x%02x%02x.ta",
-		     prefix, dev_path,
+		     "%s/%08x-%04x-%04x-%02x%02x%s%02x%02x%02x%02x%02x%02x.ta",
+		     ta_load_path,
 		     destination->timeLow,
 		     destination->timeMid,
 		     destination->timeHiAndVersion,
@@ -159,16 +157,14 @@ static int try_load_secure_module(const char* prefix,
 	return TA_BINARY_FOUND;
 }
 
-int TEECI_LoadSecureModule(const char* dev_path,
-			   const TEEC_UUID *destination, void *ta,
+int TEECI_LoadSecureModule(const TEEC_UUID *destination, void *ta,
 			   size_t *ta_size)
 {
 	int res = TA_BINARY_NOT_FOUND;
 	char **path = NULL;
 
 	for (path = ta_path; *path; path++) {
-		res = try_load_secure_module(*path, dev_path, destination, ta,
-					     ta_size);
+		res = try_load_secure_module(*path, destination, ta, ta_size);
 		if (res == TA_BINARY_FOUND)
 			break;
 	}

tee-supplicant/src/teec_ta_load.h

@@ -31,9 +31,7 @@
 #define TA_BINARY_FOUND 0
 #define TA_BINARY_NOT_FOUND -1
 
-/* Heap copy of TA load paths, separated by '\0' (access via ta_path) */
-extern char *ta_path_str;
-/* NULL-terminated list of paths (pointers into ta_path_str) */
+/* NULL-terminated list of paths */
 extern char **ta_path;
 
 /**
@@ -49,7 +47,6 @@ extern char **ta_path;
  *
  * @return              0 if TA was found, otherwise -1.
  */
-int TEECI_LoadSecureModule(const char *name,
-			   const TEEC_UUID *destination, void *ta,
+int TEECI_LoadSecureModule(const TEEC_UUID *destination, void *ta,
 			   size_t *ta_size);
 #endif