1 /*
2 * Copyright (c) 2005, 2014, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 #include "jni.h"
27 #include "jni_util.h"
28 #include "jvm.h"
29
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <errno.h>
34 #include <unistd.h>
35 #include <signal.h>
36 #include <dirent.h>
37 #include <ctype.h>
38 #include <sys/types.h>
39 #include <sys/types.h>
40 #include <sys/socket.h>
41 #include <sys/stat.h>
42 #include <sys/un.h>
43
44 #include "sun_tools_attach_VirtualMachineImpl.h"
45
46 #define RESTARTABLE(_cmd, _result) do { \
47 do { \
48 _result = _cmd; \
49 } while((_result == -1) && (errno == EINTR)); \
50 } while(0)
51
52 /*
53 * Defines a callback that is invoked for each process
54 */
55 typedef void (*ProcessCallback)(const pid_t pid, void* user_data);
56
57 /*
58 * Invokes the callback function for each process
59 */
60 static void forEachProcess(ProcessCallback f, void* user_data) {
61 DIR* dir;
62 struct dirent* ptr;
63
64 /*
65 * To locate the children we scan /proc looking for files that have a
66 * position integer as a filename.
67 */
68 if ((dir = opendir("/proc")) == NULL) {
69 return;
70 }
71 while ((ptr = readdir(dir)) != NULL) {
72 pid_t pid;
73
74 /* skip current/parent directories */
75 if (strcmp(ptr->d_name, ".") == 0 || strcmp(ptr->d_name, "..") == 0) {
76 continue;
77 }
78
79 /* skip files that aren't numbers */
80 pid = (pid_t)atoi(ptr->d_name);
81 if ((int)pid <= 0) {
82 continue;
83 }
84
85 /* invoke the callback */
86 (*f)(pid, user_data);
87 }
88 closedir(dir);
89 }
90
91
92 /*
93 * Returns the parent pid of a given pid, or -1 if not found
94 */
95 static pid_t getParent(pid_t pid) {
96 char state;
97 FILE* fp;
98 char stat[2048];
99 int statlen;
100 char fn[32];
101 int i, p;
102 char* s;
103
104 /*
105 * try to open /proc/%d/stat
106 */
107 sprintf(fn, "/proc/%d/stat", pid);
108 fp = fopen(fn, "r");
109 if (fp == NULL) {
110 return -1;
111 }
112
113 /*
114 * The format is: pid (command) state ppid ...
115 * As the command could be anything we must find the right most
116 * ")" and then skip the white spaces that follow it.
117 */
118 statlen = fread(stat, 1, 2047, fp);
119 stat[statlen] = '\0';
120 fclose(fp);
121 s = strrchr(stat, ')');
122 if (s == NULL) {
123 return -1;
124 }
125 do s++; while (isspace(*s));
126 i = sscanf(s, "%c %d", &state, &p);
127 return (pid_t)p;
128 }
129
130
131 /*
132 * Class: sun_tools_attach_VirtualMachineImpl
133 * Method: socket
134 * Signature: ()I
135 */
136 JNIEXPORT jint JNICALL Java_sun_tools_attach_VirtualMachineImpl_socket
137 (JNIEnv *env, jclass cls)
138 {
139 int fd = socket(PF_UNIX, SOCK_STREAM, 0);
140 if (fd == -1) {
141 JNU_ThrowIOExceptionWithLastError(env, "socket");
142 }
143 return (jint)fd;
144 }
145
146 /*
147 * Class: sun_tools_attach_VirtualMachineImpl
148 * Method: connect
149 * Signature: (ILjava/lang/String;)I
150 */
151 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_connect
152 (JNIEnv *env, jclass cls, jint fd, jstring path)
153 {
154 jboolean isCopy;
155 const char* p = GetStringPlatformChars(env, path, &isCopy);
156 if (p != NULL) {
157 struct sockaddr_un addr;
158 int err = 0;
159
160 memset(&addr, 0, sizeof(addr));
161 addr.sun_family = AF_UNIX;
162 /* strncpy is safe because addr.sun_path was zero-initialized before. */
163 strncpy(addr.sun_path, p, sizeof(addr.sun_path) - 1);
164
165 if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
166 err = errno;
167 }
168
169 if (isCopy) {
170 JNU_ReleaseStringPlatformChars(env, path, p);
171 }
172
173 /*
174 * If the connect failed then we throw the appropriate exception
175 * here (can't throw it before releasing the string as can't call
176 * JNI with pending exception)
177 */
178 if (err != 0) {
179 if (err == ENOENT) {
180 JNU_ThrowByName(env, "java/io/FileNotFoundException", NULL);
181 } else {
182 char* msg = strdup(strerror(err));
183 JNU_ThrowIOException(env, msg);
184 if (msg != NULL) {
185 free(msg);
186 }
187 }
188 }
189 }
190 }
191
192 /*
193 * Class: sun_tools_attach_VirtualMachineImpl
194 * Method: isLinuxThreads
195 * Signature: ()V
196 */
197 JNIEXPORT jboolean JNICALL Java_sun_tools_attach_VirtualMachineImpl_isLinuxThreads
198 (JNIEnv *env, jclass cls)
199 {
200 # ifndef _CS_GNU_LIBPTHREAD_VERSION
201 # define _CS_GNU_LIBPTHREAD_VERSION 3
202 # endif
203 size_t n;
204 char* s;
205 jboolean res;
206
207 n = confstr(_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
208 if (n <= 0) {
209 /* glibc before 2.3.2 only has LinuxThreads */
210 return JNI_TRUE;
211 }
212
213 s = (char *)malloc(n);
214 if (s == NULL) {
215 JNU_ThrowOutOfMemoryError(env, "malloc failed");
216 return JNI_TRUE;
217 }
218 confstr(_CS_GNU_LIBPTHREAD_VERSION, s, n);
219
220 /*
221 * If the LIBPTHREAD version include "NPTL" then we know we
222 * have the new threads library and not LinuxThreads
223 */
224 res = (jboolean)(strstr(s, "NPTL") == NULL);
225 free(s);
226 return res;
227 }
228
229 /*
230 * Structure and callback function used to count the children of
231 * a given process, and record the pid of the "manager thread".
232 */
233 typedef struct {
234 pid_t ppid;
235 int count;
236 pid_t mpid;
237 } ChildCountContext;
238
239 static void ChildCountCallback(const pid_t pid, void* user_data) {
240 ChildCountContext* context = (ChildCountContext*)user_data;
241 if (getParent(pid) == context->ppid) {
242 context->count++;
243 /*
244 * Remember the pid of the first child. If the final count is
245 * one then this is the pid of the LinuxThreads manager.
246 */
247 if (context->count == 1) {
248 context->mpid = pid;
249 }
250 }
251 }
252
253 /*
254 * Class: sun_tools_attach_VirtualMachineImpl
255 * Method: getLinuxThreadsManager
256 * Signature: (I)I
257 */
258 JNIEXPORT jint JNICALL Java_sun_tools_attach_VirtualMachineImpl_getLinuxThreadsManager
259 (JNIEnv *env, jclass cls, jint pid)
260 {
261 ChildCountContext context;
262
263 /*
264 * Iterate over all processes to find how many children 'pid' has
265 */
266 context.ppid = pid;
267 context.count = 0;
268 context.mpid = (pid_t)0;
269 forEachProcess(ChildCountCallback, (void*)&context);
270
271 /*
272 * If there's no children then this is likely the pid of the primordial
273 * created by the launcher - in that case the LinuxThreads manager is the
274 * parent of this process.
275 */
276 if (context.count == 0) {
277 pid_t parent = getParent(pid);
278 if ((int)parent > 0) {
279 return (jint)parent;
280 }
281 }
282
283 /*
284 * There's one child so this is likely the embedded VM case where the
285 * the primordial thread == LinuxThreads initial thread. The LinuxThreads
286 * manager in that case is the child.
287 */
288 if (context.count == 1) {
289 return (jint)context.mpid;
290 }
291
292 /*
293 * If we get here it's most likely we were given the wrong pid
294 */
295 JNU_ThrowIOException(env, "Unable to get pid of LinuxThreads manager thread");
296 return -1;
297 }
298
299 /*
300 * Structure and callback function used to send a QUIT signal to all
301 * children of a given process
302 */
303 typedef struct {
304 pid_t ppid;
305 } SendQuitContext;
306
307 static void SendQuitCallback(const pid_t pid, void* user_data) {
308 SendQuitContext* context = (SendQuitContext*)user_data;
309 pid_t parent = getParent(pid);
310 if (parent == context->ppid) {
311 kill(pid, SIGQUIT);
312 }
313 }
314
315 /*
316 * Class: sun_tools_attach_VirtualMachineImpl
317 * Method: sendQuitToChildrenOf
318 * Signature: (I)V
319 */
320 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_sendQuitToChildrenOf
321 (JNIEnv *env, jclass cls, jint pid)
322 {
323 SendQuitContext context;
324 context.ppid = (pid_t)pid;
325
326 /*
327 * Iterate over all children of 'pid' and send a QUIT signal to each.
328 */
329 forEachProcess(SendQuitCallback, (void*)&context);
330 }
331
332 /*
333 * Class: sun_tools_attach_VirtualMachineImpl
334 * Method: sendQuitTo
335 * Signature: (I)V
336 */
337 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_sendQuitTo
338 (JNIEnv *env, jclass cls, jint pid)
339 {
340 if (kill((pid_t)pid, SIGQUIT)) {
341 JNU_ThrowIOExceptionWithLastError(env, "kill");
342 }
343 }
344
345 /*
346 * Class: sun_tools_attach_VirtualMachineImpl
347 * Method: checkPermissions
348 * Signature: (Ljava/lang/String;)V
349 */
350 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_checkPermissions
351 (JNIEnv *env, jclass cls, jstring path)
352 {
353 jboolean isCopy;
354 const char* p = GetStringPlatformChars(env, path, &isCopy);
355 if (p != NULL) {
356 struct stat64 sb;
357 uid_t uid, gid;
358 int res;
359
360 /*
361 * Check that the path is owned by the effective uid/gid of this
362 * process. Also check that group/other access is not allowed.
363 */
364 uid = geteuid();
365 gid = getegid();
366
367 res = stat64(p, &sb);
368 if (res != 0) {
369 /* save errno */
370 res = errno;
371 }
372
373 if (res == 0) {
374 char msg[100];
375 jboolean isError = JNI_FALSE;
376 if (sb.st_uid != uid) {
377 jio_snprintf(msg, sizeof(msg)-1,
378 "file should be owned by the current user (which is %d) but is owned by %d", uid, sb.st_uid);
379 isError = JNI_TRUE;
380 } else if (sb.st_gid != gid) {
381 jio_snprintf(msg, sizeof(msg)-1,
382 "file's group should be the current group (which is %d) but the group is %d", gid, sb.st_gid);
383 isError = JNI_TRUE;
384 } else if ((sb.st_mode & (S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)) != 0) {
385 jio_snprintf(msg, sizeof(msg)-1,
386 "file should only be readable and writable by the owner but has 0%03o access", sb.st_mode & 0777);
387 isError = JNI_TRUE;
388 }
389 if (isError) {
390 char buf[256];
391 jio_snprintf(buf, sizeof(buf)-1, "well-known file %s is not secure: %s", p, msg);
392 JNU_ThrowIOException(env, buf);
393 }
394 } else {
395 char* msg = strdup(strerror(res));
396 JNU_ThrowIOException(env, msg);
397 if (msg != NULL) {
398 free(msg);
399 }
400 }
401
402 if (isCopy) {
403 JNU_ReleaseStringPlatformChars(env, path, p);
404 }
405 }
406 }
407
408 /*
409 * Class: sun_tools_attach_VirtualMachineImpl
410 * Method: close
411 * Signature: (I)V
412 */
413 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_close
414 (JNIEnv *env, jclass cls, jint fd)
415 {
416 int res;
417 RESTARTABLE(close(fd), res);
418 }
419
420 /*
421 * Class: sun_tools_attach_VirtualMachineImpl
422 * Method: read
423 * Signature: (I[BI)I
424 */
425 JNIEXPORT jint JNICALL Java_sun_tools_attach_VirtualMachineImpl_read
426 (JNIEnv *env, jclass cls, jint fd, jbyteArray ba, jint off, jint baLen)
427 {
428 unsigned char buf[128];
429 size_t len = sizeof(buf);
430 ssize_t n;
431
432 size_t remaining = (size_t)(baLen - off);
433 if (len > remaining) {
434 len = remaining;
435 }
436
437 RESTARTABLE(read(fd, buf, len), n);
438 if (n == -1) {
439 JNU_ThrowIOExceptionWithLastError(env, "read");
440 } else {
441 if (n == 0) {
442 n = -1; // EOF
443 } else {
444 (*env)->SetByteArrayRegion(env, ba, off, (jint)n, (jbyte *)(buf));
445 }
446 }
447 return n;
448 }
449
450 /*
451 * Class: sun_tools_attach_VirtualMachineImpl
452 * Method: write
453 * Signature: (I[B)V
454 */
455 JNIEXPORT void JNICALL Java_sun_tools_attach_VirtualMachineImpl_write
456 (JNIEnv *env, jclass cls, jint fd, jbyteArray ba, jint off, jint bufLen)
457 {
458 size_t remaining = bufLen;
459 do {
460 unsigned char buf[128];
461 size_t len = sizeof(buf);
462 int n;
463
464 if (len > remaining) {
465 len = remaining;
466 }
467 (*env)->GetByteArrayRegion(env, ba, off, len, (jbyte *)buf);
468
469 RESTARTABLE(write(fd, buf, len), n);
470 if (n > 0) {
471 off += n;
472 remaining -= n;
473 } else {
474 JNU_ThrowIOExceptionWithLastError(env, "write");
475 return;
476 }
477
478 } while (remaining > 0);
479 }