On 8/25/23 03:20, Yeqi Fu wrote:
+#if defined(CONFIG_NATIVE_CALL)
+ /* Set the library for native bypass */
+ if (native_lib_path) {
+ if (g_file_test(native_lib_path, G_FILE_TEST_IS_REGULAR)) {
+ GString *lib = g_string_new(native_lib_path);
+ lib = g_string_prepend(lib, "LD_PRELOAD=");
+ if (envlist_appendenv(envlist, g_string_free(lib, false), ":")) {
+ fprintf(stderr,
+ "failed to append the native library to environment.\n");
+ exit(EXIT_FAILURE);
+ }
+ } else {
+ fprintf(stderr, "native library %s does not exist.\n",
+ native_lib_path);
+ exit(EXIT_FAILURE);
+ }
+ }
+#endif
Here you append to the existing LD_PRELOAD.
+ /*
+ * An error may occur when executing execv, stating that the
+ * shared library from LD_PRELOAD cannot be preloaded on a
+ * different arch. So, we find LD_PRELOAD and remove it from
+ * envp before executing the execv.
+ */
+ if (native_bypass_enabled()) {
+ i = 0;
+ while (envp[i] != NULL) {
+ if (strncmp(envp[i], "LD_PRELOAD=", 11) == 0) {
+ for (int j = i; envp[j] != NULL; j++) {
+ envp[j] = envp[j + 1];
+ }
+ } else {
+ i++;
+ }
+ }
+ }
Here you simply remove LD_PRELOAD entirely.
At most you should only remove libnative.so.
I'm not at all sure that you should be modifying the target environment at all. It's ok
for simple testing, but it is definitely error prone. There are a couple of different
solutions:
(1) Dynamically modify /etc/ld.so.preload, similar to how we handle various
/proc files.
(2) Merge libnative.so with vdso.so (and select one of two images depending on bypass
enabled).
r~
