xref: /illumos-gate/usr/src/cmd/sgs/rtld/common/debug.c (revision cb511613a15cb3949eadffd67b37d3c665b4ef22)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #include	<sys/types.h>
28 #include	<sys/stat.h>
29 #include	<sys/param.h>
30 #include	<stdio.h>
31 #include	<fcntl.h>
32 #include	<stdarg.h>
33 #include	<dlfcn.h>
34 #include	<unistd.h>
35 #include	<string.h>
36 #include	<thread.h>
37 #include	<debug.h>
38 #include	"_rtld.h"
39 #include	"_elf.h"
40 #include	"msg.h"
41 
42 
43 static int		dbg_fd;		/* debugging output file descriptor */
44 static dev_t		dbg_dev;
45 static rtld_ino_t	dbg_ino;
46 static pid_t		pid;
47 
48 /*
49  * Enable diagnostic output.  All debugging functions reside in the linker
50  * debugging library liblddbg.so which is lazy loaded when required.
51  */
52 uintptr_t
53 dbg_setup(const char *options, Dbg_desc *dbp)
54 {
55 	uintptr_t	ret;
56 	rtld_stat_t	status;
57 
58 	/*
59 	 * If we're running secure, only allow debugging if ld.so.1 itself is
60 	 * owned by root and has its mode setuid.  Fail silently.
61 	 */
62 	if ((rtld_flags & RT_FL_SECURE) && (is_rtld_setuid() == 0))
63 		return (0);
64 
65 	/*
66 	 * As Dbg_setup() will effectively lazy load the necessary support
67 	 * libraries, make sure ld.so.1 is initialized for plt relocations.
68 	 */
69 	if (elf_rtld_load() == 0)
70 		return (0);
71 
72 	/*
73 	 * Call the debugging setup routine.  This function verifies the
74 	 * debugging tokens provided and returns a mask indicating the debugging
75 	 * categories selected.  The mask effectively enables calls to the
76 	 * debugging library.
77 	 */
78 	if ((ret = Dbg_setup(options, dbp)) != (uintptr_t)1)
79 		return (ret);
80 
81 	/*
82 	 * If an LD_DEBUG_OUTPUT file was specified then we need to direct all
83 	 * diagnostics to the specified file.  Add the process id as a file
84 	 * suffix so that multiple processes that inherit the same debugging
85 	 * environment variable don't fight over the same file.
86 	 */
87 	if (dbg_file) {
88 		char 	file[MAXPATHLEN];
89 
90 		(void) snprintf(file, MAXPATHLEN, MSG_ORIG(MSG_DBG_FILE),
91 		    dbg_file, getpid());
92 		if ((dbg_fd = open(file, (O_RDWR | O_CREAT), 0666)) == -1) {
93 			int	err = errno;
94 
95 			eprintf(&lml_rtld, ERR_FATAL, MSG_INTL(MSG_SYS_OPEN),
96 			    file, strerror(err));
97 			dbp->d_class = 0;
98 			return (0);
99 		}
100 	} else {
101 		/*
102 		 * The default is to direct debugging to the stderr.
103 		 */
104 		dbg_fd = 2;
105 	}
106 
107 	/*
108 	 * Initialize the dev/inode pair to enable us to determine if
109 	 * the debugging file descriptor is still available once the
110 	 * application has been entered.
111 	 */
112 	(void) rtld_fstat(dbg_fd, &status);
113 	dbg_dev = status.st_dev;
114 	dbg_ino = status.st_ino;
115 	pid = getpid();
116 
117 	return (ret);
118 }
119 
120 static int
121 dbg_lmid(Lm_list *lml)
122 {
123 	const char	*str;
124 	Aliste		idx;
125 
126 	for (APLIST_TRAVERSE(dbg_desc->d_list, idx, str)) {
127 		if (strcmp(lml->lm_lmidstr, str) == 0)
128 			return (1);
129 	}
130 	return (0);
131 }
132 
133 /*
134  * All diagnostic requests are funneled to this routine.
135  */
136 /* PRINTFLIKE2 */
137 void
138 dbg_print(Lm_list *lml, const char *format, ...)
139 {
140 	va_list		args;
141 	char		buffer[ERRSIZE + 1];
142 	pid_t		_pid;
143 	rtld_stat_t	status;
144 	Prfbuf		prf;
145 
146 	/*
147 	 * Knock off any newline indicator to signify that a diagnostic has
148 	 * been processed.
149 	 */
150 	dbg_desc->d_extra &= ~DBG_E_STDNL;
151 
152 	/*
153 	 * If debugging has been isolated to individual link-map lists,
154 	 * determine whether this request originates from a link-map list that
155 	 * is being monitored.  Otherwise, process all link-map list diagnostics
156 	 * except those that originate from ld.so.1 processing its own
157 	 * dependencies.
158 	 */
159 	if (dbg_desc->d_list && lml && lml->lm_lmidstr) {
160 		if (dbg_lmid(lml) == 0)
161 			return;
162 	} else if (lml && (lml->lm_flags & LML_FLG_RTLDLM))
163 		return;
164 
165 	/*
166 	 * If we're in the application make sure the debugging file descriptor
167 	 * is still available (ie, the user hasn't closed and/or reused the
168 	 * same descriptor).
169 	 */
170 	if (rtld_flags & RT_FL_APPLIC) {
171 		if ((rtld_fstat(dbg_fd, &status) == -1) ||
172 		    (status.st_dev != dbg_dev) ||
173 		    (status.st_ino != dbg_ino)) {
174 			if (dbg_file) {
175 				/*
176 				 * If the user specified output file has been
177 				 * disconnected try and reconnect to it.
178 				 */
179 				char 	file[MAXPATHLEN];
180 
181 				(void) snprintf(file, MAXPATHLEN,
182 				    MSG_ORIG(MSG_DBG_FILE), dbg_file, pid);
183 				if ((dbg_fd = open(file, (O_RDWR | O_APPEND),
184 				    0)) == -1) {
185 					dbg_desc->d_class = 0;
186 					return;
187 				}
188 				(void) rtld_fstat(dbg_fd, &status);
189 				dbg_dev = status.st_dev;
190 				dbg_ino = status.st_ino;
191 			} else {
192 				/*
193 				 * If stderr has been stolen from us simply
194 				 * turn debugging off.
195 				 */
196 				dbg_desc->d_class = 0;
197 				return;
198 			}
199 		}
200 	}
201 
202 	prf.pr_buf = prf.pr_cur = buffer;
203 	prf.pr_len = ERRSIZE;
204 	prf.pr_fd = dbg_fd;
205 
206 	/*
207 	 * The getpid() call is a 'special' interface between ld.so.1 and dbx,
208 	 * because of this getpid() can't be called freely until after control
209 	 * has been given to the user program.  Once the control has been given
210 	 * to the user program we know that the r_debug structure has been
211 	 * properly initialized for the debugger.
212 	 */
213 	if (rtld_flags & RT_FL_APPLIC)
214 		_pid = getpid();
215 	else
216 		_pid = pid;
217 
218 	if (lml)
219 		(void) bufprint(&prf, MSG_ORIG(MSG_DBG_PID), _pid);
220 	else
221 		(void) bufprint(&prf, MSG_ORIG(MSG_DBG_UNDEF));
222 	prf.pr_cur--;
223 
224 	if (DBG_ISLMID() && lml && lml->lm_lmidstr) {
225 		(void) bufprint(&prf, MSG_ORIG(MSG_DBG_LMID), lml->lm_lmidstr);
226 		prf.pr_cur--;
227 	}
228 	if (rtld_flags & RT_FL_THREADS) {
229 		(void) bufprint(&prf, MSG_ORIG(MSG_DBG_THREAD), rt_thr_self());
230 		prf.pr_cur--;
231 	}
232 
233 	/*
234 	 * Format the message and print it.
235 	 */
236 	va_start(args, format);
237 	(void) doprf(format, args, &prf);
238 	*(prf.pr_cur - 1) = '\n';
239 	(void) dowrite(&prf);
240 	va_end(args);
241 }
242