1/*
2   Unix SMB/CIFS implementation.
3   Critical Fault handling
4   Copyright (C) Andrew Tridgell 1992-1998
5   Copyright (C) Tim Prouty 2009
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 3 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#include "includes.h"
22
23#ifdef HAVE_SYS_SYSCTL_H
24#include <sys/sysctl.h>
25#endif
26
27
28#ifdef HAVE_SYS_PRCTL_H
29#include <sys/prctl.h>
30#endif
31
32static void (*cont_fn)(void *);
33static char *corepath;
34
35/*******************************************************************
36report a fault
37********************************************************************/
38static void fault_report(int sig)
39{
40	static int counter;
41
42	if (counter) _exit(1);
43
44	counter++;
45
46	DEBUGSEP(0);
47	DEBUG(0,("INTERNAL ERROR: Signal %d in pid %d (%s)",sig,(int)sys_getpid(),samba_version_string()));
48	DEBUG(0,("\nPlease read the Trouble-Shooting section of the Samba3-HOWTO\n"));
49	DEBUG(0,("\nFrom: http://www.samba.org/samba/docs/Samba3-HOWTO.pdf\n"));
50	DEBUGSEP(0);
51
52	smb_panic("internal error");
53
54	if (cont_fn) {
55		cont_fn(NULL);
56#ifdef SIGSEGV
57		CatchSignal(SIGSEGV,SIGNAL_CAST SIG_DFL);
58#endif
59#ifdef SIGBUS
60		CatchSignal(SIGBUS,SIGNAL_CAST SIG_DFL);
61#endif
62#ifdef SIGABRT
63		CatchSignal(SIGABRT,SIGNAL_CAST SIG_DFL);
64#endif
65		return; /* this should cause a core dump */
66	}
67	exit(1);
68}
69
70/****************************************************************************
71catch serious errors
72****************************************************************************/
73static void sig_fault(int sig)
74{
75	fault_report(sig);
76}
77
78/*******************************************************************
79setup our fault handlers
80********************************************************************/
81void fault_setup(void (*fn)(void *))
82{
83	cont_fn = fn;
84
85#ifdef SIGSEGV
86	CatchSignal(SIGSEGV,SIGNAL_CAST sig_fault);
87#endif
88#ifdef SIGBUS
89	CatchSignal(SIGBUS,SIGNAL_CAST sig_fault);
90#endif
91#ifdef SIGABRT
92	CatchSignal(SIGABRT,SIGNAL_CAST sig_fault);
93#endif
94}
95
96/**
97 * Build up the default corepath as "<logbase>/cores/<progname>"
98 */
99static char *get_default_corepath(const char *logbase, const char *progname)
100{
101	char *tmp_corepath;
102
103	/* Setup core dir in logbase. */
104	tmp_corepath = talloc_asprintf(NULL, "%s/cores", logbase);
105	if (!tmp_corepath)
106		return NULL;
107
108	if ((mkdir(tmp_corepath, 0700) == -1) && errno != EEXIST)
109		goto err_out;
110
111	if (chmod(tmp_corepath, 0700) == -1)
112		goto err_out;
113
114	talloc_free(tmp_corepath);
115
116	/* Setup progname-specific core subdir */
117	tmp_corepath = talloc_asprintf(NULL, "%s/cores/%s", logbase, progname);
118	if (!tmp_corepath)
119		return NULL;
120
121	if (mkdir(tmp_corepath, 0700) == -1 && errno != EEXIST)
122		goto err_out;
123
124	if (chown(tmp_corepath, getuid(), getgid()) == -1)
125		goto err_out;
126
127	if (chmod(tmp_corepath, 0700) == -1)
128		goto err_out;
129
130	return tmp_corepath;
131
132 err_out:
133	talloc_free(tmp_corepath);
134	return NULL;
135}
136
137/**
138 * Get the FreeBSD corepath.
139 *
140 * On FreeBSD the current working directory is ignored when creating a core
141 * file.  Instead the core directory is controlled via sysctl.  This consults
142 * the value of "kern.corefile" so the correct corepath can be printed out
143 * before dump_core() calls abort.
144 */
145#if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
146static char *get_freebsd_corepath(void)
147{
148	char *tmp_corepath = NULL;
149	char *end = NULL;
150	size_t len = 128;
151	int ret;
152
153	/* Loop with increasing sizes so we don't allocate too much. */
154	do {
155		if (len > 1024)  {
156			goto err_out;
157		}
158
159		tmp_corepath = (char *)talloc_realloc(NULL, tmp_corepath,
160						      char, len);
161		if (!tmp_corepath) {
162			return NULL;
163		}
164
165		ret = sysctlbyname("kern.corefile", tmp_corepath, &len, NULL,
166				   0);
167		if (ret == -1) {
168			if (errno != ENOMEM) {
169				DEBUG(0, ("sysctlbyname failed getting "
170					  "kern.corefile %s\n",
171					  strerror(errno)));
172				goto err_out;
173			}
174
175			/* Not a large enough array, try a bigger one. */
176			len = len << 1;
177		}
178	} while (ret == -1);
179
180	/* Strip off the common filename expansion */
181	if ((end = strrchr_m(tmp_corepath, '/'))) {
182		*end = '\0';
183	}
184
185	return tmp_corepath;
186
187 err_out:
188	if (tmp_corepath) {
189		talloc_free(tmp_corepath);
190	}
191	return NULL;
192}
193#endif
194
195/**
196 * Try getting system-specific corepath if one exists.
197 *
198 * If the system doesn't define a corepath, then the default is used.
199 */
200static char *get_corepath(const char *logbase, const char *progname)
201{
202#if (defined(FREEBSD) && defined(HAVE_SYSCTLBYNAME))
203
204	/* @todo: Add support for the linux corepath. */
205
206	char *tmp_corepath = NULL;
207	tmp_corepath = get_freebsd_corepath();
208
209	/* If this has been set correctly, we're done. */
210	if (tmp_corepath) {
211		return tmp_corepath;
212	}
213#endif
214
215	/* Fall back to the default. */
216	return get_default_corepath(logbase, progname);
217}
218
219/*******************************************************************
220make all the preparations to safely dump a core file
221********************************************************************/
222
223void dump_core_setup(const char *progname)
224{
225	char *logbase = NULL;
226	char *end = NULL;
227
228	if (lp_logfile() && *lp_logfile()) {
229		if (asprintf(&logbase, "%s", lp_logfile()) < 0) {
230			return;
231		}
232		if ((end = strrchr_m(logbase, '/'))) {
233			*end = '\0';
234		}
235	} else {
236		/* We will end up here if the log file is given on the command
237		 * line by the -l option but the "log file" option is not set
238		 * in smb.conf.
239		 */
240		if (asprintf(&logbase, "%s", get_dyn_LOGFILEBASE()) < 0) {
241			return;
242		}
243	}
244
245	SMB_ASSERT(progname != NULL);
246
247	corepath = get_corepath(logbase, progname);
248	if (!corepath) {
249		DEBUG(0, ("Unable to setup corepath for %s: %s\n", progname,
250			  strerror(errno)));
251		goto out;
252	}
253
254
255#ifdef HAVE_GETRLIMIT
256#ifdef RLIMIT_CORE
257	{
258		struct rlimit rlp;
259		getrlimit(RLIMIT_CORE, &rlp);
260		rlp.rlim_cur = MAX(16*1024*1024,rlp.rlim_cur);
261		setrlimit(RLIMIT_CORE, &rlp);
262		getrlimit(RLIMIT_CORE, &rlp);
263		DEBUG(3,("Maximum core file size limits now %d(soft) %d(hard)\n",
264			 (int)rlp.rlim_cur,(int)rlp.rlim_max));
265	}
266#endif
267#endif
268
269#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
270	/* On Linux we lose the ability to dump core when we change our user
271	 * ID. We know how to dump core safely, so let's make sure we have our
272	 * dumpable flag set.
273	 */
274	prctl(PR_SET_DUMPABLE, 1);
275#endif
276
277	/* FIXME: if we have a core-plus-pid facility, configurably set
278	 * this up here.
279	 */
280 out:
281	SAFE_FREE(logbase);
282}
283
284 void dump_core(void)
285{
286	static bool called;
287
288	if (called) {
289		DEBUG(0, ("dump_core() called recursive\n"));
290		exit(1);
291	}
292	called = true;
293
294	/* Note that even if core dumping has been disabled, we still set up
295	 * the core path. This is to handle the case where core dumping is
296	 * turned on in smb.conf and the relevant daemon is not restarted.
297	 */
298	if (!lp_enable_core_files()) {
299		DEBUG(0, ("Exiting on internal error (core file administratively disabled)\n"));
300		exit(1);
301	}
302
303#if DUMP_CORE
304	/* If we're running as non root we might not be able to dump the core
305	 * file to the corepath.  There must not be an unbecome_root() before
306	 * we call abort(). */
307	if (geteuid() != 0) {
308		become_root();
309	}
310
311	if (corepath == NULL) {
312		DEBUG(0, ("Can not dump core: corepath not set up\n"));
313		exit(1);
314	}
315
316	if (*corepath != '\0') {
317		/* The chdir might fail if we dump core before we finish
318		 * processing the config file.
319		 */
320		if (chdir(corepath) != 0) {
321			DEBUG(0, ("unable to change to %s\n", corepath));
322			DEBUGADD(0, ("refusing to dump core\n"));
323			exit(1);
324		}
325
326		DEBUG(0,("dumping core in %s\n", corepath));
327	}
328
329	umask(~(0700));
330	dbgflush();
331
332	/* Ensure we don't have a signal handler for abort. */
333#ifdef SIGABRT
334	CatchSignal(SIGABRT,SIGNAL_CAST SIG_DFL);
335#endif
336
337	abort();
338
339#else /* DUMP_CORE */
340	exit(1);
341#endif /* DUMP_CORE */
342}
343
344