Fix "failed to find __libc_dlopen_mode in the .dynstr section" when t…

…he libc is glibc 2.34 or later.

__libc_dlopen_mode in libc was removed and dlopen was moved from libdl.so.2 to libc.so.6 in glibc 2.34.

src/linux/elf.c

@@ -56,6 +56,7 @@ int injector__collect_libc_information(injector_t *injector)
     size_t str_size = 0;
     size_t sym_offset = 0;
     size_t sym_num = 0;
+    int use_internal_dlfunc = 0;
     size_t sym_entsize = 0;
     size_t dlopen_st_name;
     size_t dlopen_offset;
@@ -124,9 +125,14 @@ int injector__collect_libc_information(injector_t *injector)
         goto cleanup;
     }
 
-    dlopen_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlopen_mode");
+    dlopen_st_name = find_strtab_offset(fp, str_offset, str_size, "dlopen");
     if (dlopen_st_name == 0) {
-        injector__set_errmsg("failed to find __libc_dlopen_mode in the .dynstr section.");
+        /* glibc 2.33 or earlier */
+        use_internal_dlfunc = 1;
+        dlopen_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlopen_mode");
+    }
+    if (dlopen_st_name == 0) {
+        injector__set_errmsg("failed to find dlopen/__libc_dlopen_mode in the .dynstr section.");
         rv = INJERR_NO_FUNCTION;
         goto cleanup;
     }
@@ -143,9 +149,13 @@ int injector__collect_libc_information(injector_t *injector)
         }
     }
 
-    dlclose_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlclose");
+    if (!use_internal_dlfunc) {
+        dlclose_st_name = find_strtab_offset(fp, str_offset, str_size, "dlclose");
+    } else {
+        dlclose_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlclose");
+    }
     if (dlclose_st_name == 0) {
-        injector__set_errmsg("failed to find __libc_dlclose in the .dynstr section.");
+        injector__set_errmsg("failed to find dlclose/__libc_dlclose in the .dynstr section.");
         rv = INJERR_NO_FUNCTION;
         goto cleanup;
     }
@@ -161,10 +171,14 @@ int injector__collect_libc_information(injector_t *injector)
             break;
         }
     }
-
-    dlsym_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlsym");
+
+    if (!use_internal_dlfunc) {
+        dlsym_st_name = find_strtab_offset(fp, str_offset, str_size, "dlsym");
+    } else {
+        dlsym_st_name = find_strtab_offset(fp, str_offset, str_size, "__libc_dlsym");
+    }
     if (dlsym_st_name == 0) {
-        injector__set_errmsg("failed to find __libc_dlsym  in the .dynstr section.");
+        injector__set_errmsg("failed to find dlsym/__libc_dlsym  in the .dynstr section.");
         rv = INJERR_NO_FUNCTION;
         goto cleanup;
     }
@@ -181,6 +195,7 @@ int injector__collect_libc_information(injector_t *injector)
         }
     }
 
+    injector->use_internal_dlfunc = use_internal_dlfunc;
     injector->dlopen_addr = libc_addr + dlopen_offset;
     injector->dlclose_addr = libc_addr + dlclose_offset;
     injector->dlsym_addr = libc_addr + dlsym_offset;

src/linux/injector.c

@@ -114,6 +114,7 @@ int injector_attach(injector_t **injector_out, pid_t pid)
 int injector_inject(injector_t *injector, const char *path, void **handle)
 {
     char abspath[PATH_MAX];
+    int dlflags = RTLD_LAZY;
     size_t len;
     int rv;
     long retval;
@@ -136,8 +137,11 @@ int injector_inject(injector_t *injector, const char *path, void **handle)
     if (rv != 0) {
         return rv;
     }
+    if (injector->use_internal_dlfunc) {
 #define __RTLD_DLOPEN	0x80000000 // glibc internal flag
-    rv = injector__call_function(injector, &retval, injector->dlopen_addr, injector->text, RTLD_LAZY | __RTLD_DLOPEN);
+        dlflags |= __RTLD_DLOPEN;
+    }
+    rv = injector__call_function(injector, &retval, injector->dlopen_addr, injector->text, dlflags);
     if (rv != 0) {
         return rv;
     }

src/linux/injector_internal.h

@@ -71,6 +71,7 @@ struct injector {
     uint8_t mmapped;
     arch_t arch;
     struct user_regs_struct regs;
+    int use_internal_dlfunc; /* true if glibc 2.33 or earlier */
     size_t dlopen_addr;
     size_t dlclose_addr;
     size_t dlsym_addr;