1 /*
  2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "classfile/javaClasses.hpp"
 27 #include "classfile/symbolTable.hpp"
 28 #include "classfile/systemDictionary.hpp"
 29 #include "classfile/vmClasses.hpp"
 30 #include "classfile/vmSymbols.hpp"
 31 #include "logging/log.hpp"
 32 #include "logging/logTag.hpp"
 33 #include "memory/oopFactory.hpp"
 34 #include "memory/resourceArea.hpp"
 35 #include "oops/instanceKlass.hpp"
 36 #include "oops/klass.inline.hpp"
 37 #include "oops/method.hpp"
 38 #include "oops/oop.inline.hpp"
 39 #include "oops/symbol.hpp"
 40 #include "prims/jvm_misc.hpp"
 41 #include "prims/jvmtiExport.hpp"
 42 #include "prims/nativeLookup.hpp"
 43 #include "prims/unsafe.hpp"
 44 #include "prims/scopedMemoryAccess.hpp"
 45 #include "prims/shipilevMagic.hpp"
 46 #include "runtime/arguments.hpp"
 47 #include "runtime/handles.inline.hpp"
 48 #include "runtime/interfaceSupport.inline.hpp"
 49 #include "runtime/javaCalls.hpp"
 50 #include "runtime/os.hpp"
 51 #include "runtime/sharedRuntime.hpp"
 52 #include "runtime/signature.hpp"
 53 #include "utilities/macros.hpp"
 54 #include "utilities/utf8.hpp"
 55 #if INCLUDE_JFR
 56 #include "jfr/jfr.hpp"
 57 #endif
 58 
 59 /*
 60 
 61 The JNI specification defines the mapping from a Java native method name to
 62 a C native library implementation function name as follows:
 63 
 64   The mapping produces a native method name by concatenating the following components
 65   derived from a `native` method declaration:
 66 
 67   1. the prefix Java_
 68   2. given the binary name, in internal form, of the class which declares the native method:
 69      the result of escaping the name.
 70   3. an underscore ("_")
 71   4. the escaped method name
 72   5. if the native method declaration is overloaded: two underscores ("__") followed by the
 73    escaped parameter descriptor (JVMS 4.3.3) of the method declaration.
 74 
 75   Escaping leaves every alphanumeric ASCII character (A-Za-z0-9) unchanged, and replaces each
 76   UTF-16 code unit n the table below with the corresponding escape sequence. If the name to be
 77   escaped contains a surrogate pair, then the high-surrogate code unit and the low-surrogate code
 78   unit are escaped separately. The result of escaping is a string consisting only of the ASCII
 79   characters A-Za-z0-9 and underscore.
 80 
 81   ------------------------------                  ------------------------------------
 82   UTF-16 code unit                                Escape sequence
 83   ------------------------------                  ------------------------------------
 84   Forward slash (/, U+002F)                       _
 85   Underscore (_, U+005F)                          _1
 86   Semicolon (;, U+003B)                           _2
 87   Left square bracket ([, U+005B)                 _3
 88   Any UTF-16 code unit \u_WXYZ_ that does not     _0wxyz where w, x, y, and z are the lower-case
 89   represent alphanumeric ASCII (A-Za-z0-9),       forms of the hexadecimal digits W, X, Y, and Z.
 90   forward slash, underscore, semicolon,           (For example, U+ABCD becomes _0abcd.)
 91   or left square bracket
 92   ------------------------------                  ------------------------------------
 93 
 94   Note that escape sequences can safely begin _0, _1, etc, because class and method
 95   names in Java source code never begin with a number. However, that is not the case in
 96   class files that were not generated from Java source code.
 97 
 98   To preserve the 1:1 mapping to a native method name, the VM checks the resulting name as
 99   follows. If the process of escaping any precursor string from the native  method declaration
100   (class or method name, or argument type) causes a "0", "1", "2", or "3" character
101   from the precursor string to appear unchanged in the result *either* immediately after an
102   underscore *or* at the beginning of the escaped string (where it will follow an underscore
103   in the fully assembled name), then the escaping process is said to have "failed".
104   In such cases, no native library search is performed, and the attempt to link the native
105   method invocation will throw UnsatisfiedLinkError.
106 
107 
108 For example:
109 
110   package/my_class/method
111 
112 and
113 
114   package/my/1class/method
115 
116 both map to
117 
118   Java_package_my_1class_method
119 
120 To address this potential conflict we need only check if the character after
121 / is a digit 0..3, or if the first character after an injected '_' separator
122 is a digit 0..3. If we encounter an invalid identifier we reset the
123 stringStream and return false. Otherwise the stringStream contains the mapped
124 name and we return true.
125 
126 */
127 static bool map_escaped_name_on(stringStream* st, Symbol* name, int begin, int end) {
128   char* bytes = (char*)name->bytes() + begin;
129   char* end_bytes = (char*)name->bytes() + end;
130   bool check_escape_char = true; // initially true as first character here follows '_'
131   while (bytes < end_bytes) {
132     jchar c;
133     bytes = UTF8::next(bytes, &c);
134     if (c <= 0x7f && isalnum(c)) {
135       if (check_escape_char && (c >= '0' && c <= '3')) {
136         // This is a non-Java identifier and we won't escape it to
137         // ensure no name collisions with a Java identifier.
138         if (log_is_enabled(Debug, jni, resolve)) {
139           ResourceMark rm;
140           log_debug(jni, resolve)("[Lookup of native method with non-Java identifier rejected: %s]",
141                                   name->as_C_string());
142         }
143         st->reset();  // restore to "" on error
144         return false;
145       }
146       st->put((char) c);
147       check_escape_char = false;
148     } else {
149       check_escape_char = false;
150       if (c == '_') st->print("_1");
151       else if (c == '/') {
152         st->print("_");
153         // Following a / we must have non-escape character
154         check_escape_char = true;
155       }
156       else if (c == ';') st->print("_2");
157       else if (c == '[') st->print("_3");
158       else               st->print("_%.5x", c);
159     }
160   }
161   return true;
162 }
163 
164 
165 static bool map_escaped_name_on(stringStream* st, Symbol* name) {
166   return map_escaped_name_on(st, name, 0, name->utf8_length());
167 }
168 
169 
170 char* NativeLookup::pure_jni_name(const methodHandle& method) {
171   stringStream st;
172   // Prefix
173   st.print("Java_");
174   // Klass name
175   if (!map_escaped_name_on(&st, method->klass_name())) {
176     return nullptr;
177   }
178   st.print("_");
179   // Method name
180   if (!map_escaped_name_on(&st, method->name())) {
181     return nullptr;
182   }
183   return st.as_string();
184 }
185 
186 char* NativeLookup::long_jni_name(const methodHandle& method) {
187   // Signatures ignore the wrapping parentheses and the trailing return type
188   stringStream st;
189   Symbol* signature = method->signature();
190   st.print("__");
191   // find ')'
192   int end;
193   for (end = 0; end < signature->utf8_length() && signature->char_at(end) != JVM_SIGNATURE_ENDFUNC; end++);
194   // skip first '('
195   if (!map_escaped_name_on(&st, signature, 1, end)) {
196     return nullptr;
197   }
198 
199   return st.as_string();
200 }
201 
202 extern "C" {
203   void JNICALL JVM_RegisterMethodHandleMethods(JNIEnv *env, jclass unsafecls);
204   void JNICALL JVM_RegisterReferencesMethods(JNIEnv *env, jclass unsafecls);
205   void JNICALL JVM_RegisterUpcallHandlerMethods(JNIEnv *env, jclass unsafecls);
206   void JNICALL JVM_RegisterUpcallLinkerMethods(JNIEnv *env, jclass unsafecls);
207   void JNICALL JVM_RegisterNativeEntryPointMethods(JNIEnv *env, jclass unsafecls);
208   void JNICALL JVM_RegisterPerfMethods(JNIEnv *env, jclass perfclass);
209   void JNICALL JVM_RegisterWhiteBoxMethods(JNIEnv *env, jclass wbclass);
210   void JNICALL JVM_RegisterVectorSupportMethods(JNIEnv *env, jclass vsclass);
211 #if INCLUDE_JVMCI
212   jobject  JNICALL JVM_GetJVMCIRuntime(JNIEnv *env, jclass c);
213   void     JNICALL JVM_RegisterJVMCINatives(JNIEnv *env, jclass compilerToVMClass);
214 #endif
215 }
216 
217 #define CC (char*)  /* cast a literal from (const char*) */
218 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
219 
220 static JNINativeMethod lookup_special_native_methods[] = {
221   { CC"Java_jdk_internal_misc_Unsafe_registerNatives",             nullptr, FN_PTR(JVM_RegisterJDKInternalMiscUnsafeMethods) },
222   { CC"Java_java_lang_invoke_MethodHandleNatives_registerNatives", nullptr, FN_PTR(JVM_RegisterMethodHandleMethods) },
223   { CC"Java_jdk_internal_foreign_abi_UpcallStubs_registerNatives",      nullptr, FN_PTR(JVM_RegisterUpcallHandlerMethods) },
224   { CC"Java_jdk_internal_foreign_abi_UpcallLinker_registerNatives",      nullptr, FN_PTR(JVM_RegisterUpcallLinkerMethods) },
225   { CC"Java_jdk_internal_foreign_abi_NativeEntryPoint_registerNatives",      nullptr, FN_PTR(JVM_RegisterNativeEntryPointMethods) },
226   { CC"Java_jdk_internal_perf_Perf_registerNatives",               nullptr, FN_PTR(JVM_RegisterPerfMethods)         },
227   { CC"Java_sun_hotspot_WhiteBox_registerNatives",                 nullptr, FN_PTR(JVM_RegisterWhiteBoxMethods)     },
228   { CC"Java_jdk_test_whitebox_WhiteBox_registerNatives",           nullptr, FN_PTR(JVM_RegisterWhiteBoxMethods)     },
229   { CC"Java_jdk_internal_vm_vector_VectorSupport_registerNatives", nullptr, FN_PTR(JVM_RegisterVectorSupportMethods)},
230 #if INCLUDE_JVMCI
231   { CC"Java_jdk_vm_ci_runtime_JVMCI_initializeRuntime",            nullptr, FN_PTR(JVM_GetJVMCIRuntime)             },
232   { CC"Java_jdk_vm_ci_hotspot_CompilerToVM_registerNatives",       nullptr, FN_PTR(JVM_RegisterJVMCINatives)        },
233 #endif
234 #if INCLUDE_JFR
235   { CC"Java_jdk_jfr_internal_JVM_registerNatives",                 nullptr, FN_PTR(jfr_register_natives)            },
236 #endif
237   { CC"Java_jdk_internal_misc_ScopedMemoryAccess_registerNatives", nullptr, FN_PTR(JVM_RegisterJDKInternalMiscScopedMemoryAccessMethods) },
238   { CC"Java_net_shipilev_Magic_registerNatives",                   nullptr, FN_PTR(JVM_RegisterNetShipilevMagicMethods) },
239 };
240 
241 static address lookup_special_native(const char* jni_name) {
242   int count = sizeof(lookup_special_native_methods) / sizeof(JNINativeMethod);
243   for (int i = 0; i < count; i++) {
244     // NB: To ignore the jni prefix and jni postfix strstr is used matching.
245     if (strstr(jni_name, lookup_special_native_methods[i].name) != nullptr) {
246       return CAST_FROM_FN_PTR(address, lookup_special_native_methods[i].fnPtr);
247     }
248   }
249   return nullptr;
250 }
251 
252 address NativeLookup::lookup_style(const methodHandle& method, char* pure_name, const char* long_name, int args_size, bool os_style, TRAPS) {
253   address entry;
254   const char* jni_name = compute_complete_jni_name(pure_name, long_name, args_size, os_style);
255 
256 
257   // If the loader is null we have a system class, so we attempt a lookup in
258   // the native Java library. This takes care of any bootstrapping problems.
259   // Note: It is critical for bootstrapping that Java_java_lang_ClassLoader_findNative
260   // gets found the first time around - otherwise an infinite loop can occur. This is
261   // another VM/library dependency
262   Handle loader(THREAD, method->method_holder()->class_loader());
263   if (loader.is_null()) {
264     entry = lookup_special_native(jni_name);
265     if (entry == nullptr) {
266        entry = (address) os::dll_lookup(os::native_java_library(), jni_name);
267     }
268     if (entry != nullptr) {
269       return entry;
270     }
271   }
272 
273   // Otherwise call static method findNative in ClassLoader
274   Klass*   klass = vmClasses::ClassLoader_klass();
275   Handle name_arg = java_lang_String::create_from_str(jni_name, CHECK_NULL);
276 
277   JavaValue result(T_LONG);
278   JavaCalls::call_static(&result,
279                          klass,
280                          vmSymbols::findNative_name(),
281                          vmSymbols::classloader_string_long_signature(),
282                          // Arguments
283                          loader,
284                          name_arg,
285                          CHECK_NULL);
286   entry = (address) (intptr_t) result.get_jlong();
287 
288   if (entry == nullptr) {
289     // findNative didn't find it, if there are any agent libraries look in them
290     AgentLibrary* agent;
291     for (agent = Arguments::agents(); agent != nullptr; agent = agent->next()) {
292       entry = (address) os::dll_lookup(agent->os_lib(), jni_name);
293       if (entry != nullptr) {
294         return entry;
295       }
296     }
297   }
298 
299   return entry;
300 }
301 
302 const char* NativeLookup::compute_complete_jni_name(const char* pure_name, const char* long_name, int args_size, bool os_style) {
303   stringStream st;
304   if (os_style) {
305     os::print_jni_name_prefix_on(&st, args_size);
306   }
307 
308   st.print_raw(pure_name);
309   st.print_raw(long_name);
310   if (os_style) {
311     os::print_jni_name_suffix_on(&st, args_size);
312   }
313 
314   return st.as_string();
315 }
316 
317 // Check all the formats of native implementation name to see if there is one
318 // for the specified method.
319 address NativeLookup::lookup_entry(const methodHandle& method, TRAPS) {
320   address entry = nullptr;
321   // Compute pure name
322   char* pure_name = pure_jni_name(method);
323   if (pure_name == nullptr) {
324     // JNI name mapping rejected this method so return
325     // null to indicate UnsatisfiedLinkError should be thrown.
326     return nullptr;
327   }
328 
329   // Compute argument size
330   int args_size = 1                             // JNIEnv
331                 + (method->is_static() ? 1 : 0) // class for static methods
332                 + method->size_of_parameters(); // actual parameters
333 
334   // 1) Try JNI short style
335   entry = lookup_style(method, pure_name, "",        args_size, true,  CHECK_NULL);
336   if (entry != nullptr) return entry;
337 
338   // Compute long name
339   char* long_name = long_jni_name(method);
340   if (long_name == nullptr) {
341     // JNI name mapping rejected this method so return
342     // null to indicate UnsatisfiedLinkError should be thrown.
343     return nullptr;
344   }
345 
346   // 2) Try JNI long style
347   entry = lookup_style(method, pure_name, long_name, args_size, true,  CHECK_NULL);
348   if (entry != nullptr) return entry;
349 
350   // 3) Try JNI short style without os prefix/suffix
351   entry = lookup_style(method, pure_name, "",        args_size, false, CHECK_NULL);
352   if (entry != nullptr) return entry;
353 
354   // 4) Try JNI long style without os prefix/suffix
355   entry = lookup_style(method, pure_name, long_name, args_size, false, CHECK_NULL);
356 
357   return entry; // null indicates not found
358 }
359 
360 // Check if there are any JVM TI prefixes which have been applied to the native method name.
361 // If any are found, remove them before attempting the look up of the
362 // native implementation again.
363 // See SetNativeMethodPrefix in the JVM TI Spec for more details.
364 address NativeLookup::lookup_entry_prefixed(const methodHandle& method, TRAPS) {
365 #if INCLUDE_JVMTI
366   ResourceMark rm(THREAD);
367 
368   int prefix_count;
369   char** prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
370   char* in_name = method->name()->as_C_string();
371   char* wrapper_name = in_name;
372   // last applied prefix will be first -- go backwards
373   for (int i = prefix_count-1; i >= 0; i--) {
374     char* prefix = prefixes[i];
375     size_t prefix_len = strlen(prefix);
376     if (strncmp(prefix, wrapper_name, prefix_len) == 0) {
377       // has this prefix remove it
378       wrapper_name += prefix_len;
379     }
380   }
381   if (wrapper_name != in_name) {
382     // we have a name for a wrapping method
383     int wrapper_name_len = (int)strlen(wrapper_name);
384     TempNewSymbol wrapper_symbol = SymbolTable::probe(wrapper_name, wrapper_name_len);
385     if (wrapper_symbol != nullptr) {
386       Klass* k = method->method_holder();
387       Method* wrapper_method = k->lookup_method(wrapper_symbol, method->signature());
388       if (wrapper_method != nullptr && !wrapper_method->is_native()) {
389         // we found a wrapper method, use its native entry
390         method->set_is_prefixed_native();
391         return lookup_entry(methodHandle(THREAD, wrapper_method), THREAD);
392       }
393     }
394   }
395 #endif // INCLUDE_JVMTI
396   return nullptr;
397 }
398 
399 address NativeLookup::lookup_base(const methodHandle& method, TRAPS) {
400   address entry = nullptr;
401   ResourceMark rm(THREAD);
402 
403   entry = lookup_entry(method, CHECK_NULL);
404   if (entry != nullptr) return entry;
405 
406   // standard native method resolution has failed.  Check if there are any
407   // JVM TI prefixes which have been applied to the native method name.
408   entry = lookup_entry_prefixed(method, CHECK_NULL);
409   if (entry != nullptr) return entry;
410 
411   // Native function not found, throw UnsatisfiedLinkError
412   stringStream ss;
413   ss.print("'");
414   method->print_external_name(&ss);
415   ss.print("'");
416   THROW_MSG_0(vmSymbols::java_lang_UnsatisfiedLinkError(), ss.as_string());
417 }
418 
419 
420 address NativeLookup::lookup(const methodHandle& method, TRAPS) {
421   if (!method->has_native_function()) {
422     address entry = lookup_base(method, CHECK_NULL);
423     method->set_native_function(entry,
424       Method::native_bind_event_is_interesting);
425     // -verbose:jni printing
426     if (log_is_enabled(Debug, jni, resolve)) {
427       ResourceMark rm(THREAD);
428       log_debug(jni, resolve)("[Dynamic-linking native method %s.%s ... JNI]",
429                               method->method_holder()->external_name(),
430                               method->name()->as_C_string());
431     }
432   }
433   return method->native_function();
434 }