1 /* Trace calls through PLTs and show caller, callee, and parameters.
2 Copyright (C) 2011-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <error.h>
20 #include <fcntl.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <unistd.h>
25 #include <sys/param.h>
26 #include <sys/uio.h>
27
28 #include <ldsodefs.h>
29
30
31 extern const char *__progname;
32 extern const char *__progname_full;
33
34
35 /* List of objects to trace calls from. */
36 static const char *fromlist;
37 /* List of objects to trace calls to. */
38 static const char *tolist;
39
40 /* If non-zero, also trace returns of the calls. */
41 static int do_exit;
42 /* If non-zero print PID for each line. */
43 static int print_pid;
44
45 /* The output stream to use. */
46 static FILE *out_file;
47
48
49 static int
match_pid(pid_t pid,const char * which)50 match_pid (pid_t pid, const char *which)
51 {
52 if (which == NULL || which[0] == '\0')
53 {
54 print_pid = 1;
55 return 1;
56 }
57
58 char *endp;
59 unsigned long n = strtoul (which, &endp, 0);
60 return *endp == '\0' && n == pid;
61 }
62
63
64 static void
init(void)65 init (void)
66 {
67 fromlist = getenv ("SOTRUSS_FROMLIST");
68 if (fromlist != NULL && fromlist[0] == '\0')
69 fromlist = NULL;
70 tolist = getenv ("SOTRUSS_TOLIST");
71 if (tolist != NULL && tolist[0] == '\0')
72 tolist = NULL;
73 do_exit = (getenv ("SOTRUSS_EXIT") ?: "")[0] != '\0';
74
75 /* Determine whether this process is supposed to be traced and if
76 yes, whether we should print into a file. */
77 const char *which_process = getenv ("SOTRUSS_WHICH");
78 pid_t pid = getpid ();
79 int out_fd = -1;
80 if (match_pid (pid, which_process))
81 {
82 const char *out_filename = getenv ("SOTRUSS_OUTNAME");
83
84 if (out_filename != NULL && out_filename[0] != 0)
85 {
86 size_t out_filename_len = strlen (out_filename) + 13;
87 char fullname[out_filename_len];
88 char *endp = stpcpy (fullname, out_filename);
89 if (which_process == NULL || which_process[0] == '\0')
90 snprintf (endp, 13, ".%ld", (long int) pid);
91
92 out_fd = open64 (fullname, O_RDWR | O_CREAT | O_TRUNC, 0666);
93 if (out_fd != -1)
94 print_pid = 0;
95 }
96 }
97
98 /* If we do not write into a file write to stderr. Duplicate the
99 descriptor so that we can keep printing in case the program
100 closes stderr. Try first to allocate a descriptor with a value
101 usually not used as to minimize interference with the
102 program. */
103 if (out_fd == -1)
104 {
105 out_fd = fcntl64 (STDERR_FILENO, F_DUPFD, 1000);
106 if (out_fd == -1)
107 out_fd = dup (STDERR_FILENO);
108 }
109
110 if (out_fd != -1)
111 {
112 /* Convert file descriptor into a stream. */
113 out_file = fdopen (out_fd, "w");
114 if (out_file != NULL)
115 setlinebuf (out_file);
116 }
117 }
118
119
120 /* Audit interface verification. We also initialize everything if
121 everything checks out OK. */
122 unsigned int
la_version(unsigned int v)123 la_version (unsigned int v)
124 {
125 if (v != LAV_CURRENT)
126 error (1, 0, "cannot handle interface version %u", v);
127
128 init ();
129
130 return v;
131 }
132
133
134 /* Check whether a file name is on the colon-separated list of file
135 names. */
136 static unsigned int
match_file(const char * list,const char * name,size_t name_len,unsigned int mask)137 match_file (const char *list, const char *name, size_t name_len,
138 unsigned int mask)
139 {
140 if (list[0] == '\0')
141 return 0;
142
143 const char *cp = list;
144 while (1)
145 {
146 if (strncmp (cp, name, name_len) == 0
147 && (cp[name_len] == ':' || cp[name_len] == '\0'))
148 return mask;
149
150 cp = strchr (cp, ':');
151 if (cp == NULL)
152 return 0;
153 ++cp;
154 }
155 }
156
157
158 unsigned int
la_objopen(struct link_map * map,Lmid_t lmid,uintptr_t * cookie)159 la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
160 {
161 if (out_file == NULL)
162 return 0;
163
164 const char *full_name = map->l_name ?: "";
165 if (full_name[0] == '\0')
166 full_name = __progname_full;
167 size_t full_name_len = strlen (full_name);
168 const char *base_name = basename (full_name);
169 if (base_name[0] == '\0')
170 base_name = __progname;
171 size_t base_name_len = strlen (base_name);
172
173 int result = 0;
174 const char *print_name = NULL;
175 for (struct libname_list *l = map->l_libname; l != NULL; l = l->next)
176 {
177 if (print_name == NULL || (print_name[0] == '/' && l->name[0] != '/'))
178 print_name = l->name;
179
180 if (fromlist != NULL)
181 result |= match_file (fromlist, l->name, strlen (l->name),
182 LA_FLG_BINDFROM);
183
184 if (tolist != NULL)
185 result |= match_file (tolist, l->name, strlen (l->name),LA_FLG_BINDTO);
186 }
187
188 if (print_name == NULL)
189 print_name = base_name;
190 if (print_name[0] == '\0')
191 print_name = __progname;
192
193 /* We cannot easily get to the object name in the PLT handling
194 functions. Use the cookie to get the string pointer passed back
195 to us. */
196 *cookie = (uintptr_t) print_name;
197
198 /* The object name has to be on the list of objects to trace calls
199 from or that list must be empty. In the latter case we trace
200 only calls from the main binary. */
201 if (fromlist == NULL)
202 result |= map->l_name[0] == '\0' ? LA_FLG_BINDFROM : 0;
203 else
204 result |= (match_file (fromlist, full_name, full_name_len,
205 LA_FLG_BINDFROM)
206 | match_file (fromlist, base_name, base_name_len,
207 LA_FLG_BINDFROM));
208
209 /* The object name has to be on the list of objects to trace calls
210 to or that list must be empty. In the latter case we trace
211 calls toall objects. */
212 if (tolist == NULL)
213 result |= LA_FLG_BINDTO;
214 else
215 result |= (match_file (tolist, full_name, full_name_len, LA_FLG_BINDTO)
216 | match_file (tolist, base_name, base_name_len, LA_FLG_BINDTO));
217
218 return result;
219 }
220
221
222 #if __ELF_NATIVE_CLASS == 32
223 # define la_symbind la_symbind32
224 typedef Elf32_Sym Elf_Sym;
225 #else
226 # define la_symbind la_symbind64
227 typedef Elf64_Sym Elf_Sym;
228 #endif
229
230 uintptr_t
la_symbind(Elf_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,unsigned int * flags,const char * symname)231 la_symbind (Elf_Sym *sym, unsigned int ndx, uintptr_t *refcook,
232 uintptr_t *defcook, unsigned int *flags, const char *symname)
233 {
234 if (!do_exit)
235 *flags = LA_SYMB_NOPLTEXIT;
236
237 return sym->st_value;
238 }
239
240
241 static void
print_enter(uintptr_t * refcook,uintptr_t * defcook,const char * symname,unsigned long int reg1,unsigned long int reg2,unsigned long int reg3,unsigned int flags)242 print_enter (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
243 unsigned long int reg1, unsigned long int reg2,
244 unsigned long int reg3, unsigned int flags)
245 {
246 char buf[3 * sizeof (pid_t) + 3];
247 buf[0] = '\0';
248 if (print_pid)
249 snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
250
251 fprintf (out_file, "%s%15s -> %-15s:%s%s(0x%lx, 0x%lx, 0x%lx)\n",
252 buf, (char *) *refcook, (char *) *defcook,
253 (flags & LA_SYMB_NOPLTEXIT) ? "*" : " ", symname, reg1, reg2, reg3);
254 }
255
256
257 #ifdef __i386__
258 Elf32_Addr
la_i86_gnu_pltenter(Elf32_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,La_i86_regs * regs,unsigned int * flags,const char * symname,long int * framesizep)259 la_i86_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
260 unsigned int ndx __attribute__ ((unused)),
261 uintptr_t *refcook, uintptr_t *defcook,
262 La_i86_regs *regs, unsigned int *flags,
263 const char *symname, long int *framesizep)
264 {
265 unsigned long int *sp = (unsigned long int *) regs->lr_esp;
266
267 print_enter (refcook, defcook, symname, sp[1], sp[2], sp[3], *flags);
268
269 /* No need to copy anything, we will not need the parameters in any case. */
270 *framesizep = 0;
271
272 return sym->st_value;
273 }
274 #elif defined __x86_64__
275 Elf64_Addr
la_x86_64_gnu_pltenter(Elf64_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,La_x86_64_regs * regs,unsigned int * flags,const char * symname,long int * framesizep)276 la_x86_64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
277 unsigned int ndx __attribute__ ((unused)),
278 uintptr_t *refcook, uintptr_t *defcook,
279 La_x86_64_regs *regs, unsigned int *flags,
280 const char *symname, long int *framesizep)
281 {
282 print_enter (refcook, defcook, symname,
283 regs->lr_rdi, regs->lr_rsi, regs->lr_rdx, *flags);
284
285 /* No need to copy anything, we will not need the parameters in any case. */
286 *framesizep = 0;
287
288 return sym->st_value;
289 }
290 #elif defined __sparc__ && !defined __arch64__
291 Elf32_Addr
la_sparc32_gnu_pltenter(Elf32_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,La_sparc32_regs * regs,unsigned int * flags,const char * symname,long int * framesizep)292 la_sparc32_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
293 unsigned int ndx __attribute__ ((unused)),
294 uintptr_t *refcook, uintptr_t *defcook,
295 La_sparc32_regs *regs, unsigned int *flags,
296 const char *symname, long int *framesizep)
297 {
298 print_enter (refcook, defcook, symname,
299 regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
300 *flags);
301
302 /* No need to copy anything, we will not need the parameters in any case. */
303 *framesizep = 0;
304
305 return sym->st_value;
306 }
307 #elif defined __sparc__ && defined __arch64__
308 Elf64_Addr
la_sparc64_gnu_pltenter(Elf64_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,La_sparc64_regs * regs,unsigned int * flags,const char * symname,long int * framesizep)309 la_sparc64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
310 unsigned int ndx __attribute__ ((unused)),
311 uintptr_t *refcook, uintptr_t *defcook,
312 La_sparc64_regs *regs, unsigned int *flags,
313 const char *symname, long int *framesizep)
314 {
315 print_enter (refcook, defcook, symname,
316 regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
317 *flags);
318
319 /* No need to copy anything, we will not need the parameters in any case. */
320 *framesizep = 0;
321
322 return sym->st_value;
323 }
324 #elif !defined HAVE_ARCH_PLTENTER
325 # warning "pltenter for architecture not supported"
326 #endif
327
328
329 static void
print_exit(uintptr_t * refcook,uintptr_t * defcook,const char * symname,unsigned long int reg)330 print_exit (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
331 unsigned long int reg)
332 {
333 char buf[3 * sizeof (pid_t) + 3];
334 buf[0] = '\0';
335 if (print_pid)
336 snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
337
338 fprintf (out_file, "%s%15s -> %-15s:%s%s - 0x%lx\n",
339 buf, (char *) *refcook, (char *) *defcook, " ", symname, reg);
340 }
341
342
343 #ifdef __i386__
344 unsigned int
la_i86_gnu_pltexit(Elf32_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,const struct La_i86_regs * inregs,struct La_i86_retval * outregs,const char * symname)345 la_i86_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
346 uintptr_t *defcook, const struct La_i86_regs *inregs,
347 struct La_i86_retval *outregs, const char *symname)
348 {
349 print_exit (refcook, defcook, symname, outregs->lrv_eax);
350
351 return 0;
352 }
353 #elif defined __x86_64__
354 unsigned int
la_x86_64_gnu_pltexit(Elf64_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,const struct La_x86_64_regs * inregs,struct La_x86_64_retval * outregs,const char * symname)355 la_x86_64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
356 uintptr_t *defcook, const struct La_x86_64_regs *inregs,
357 struct La_x86_64_retval *outregs, const char *symname)
358 {
359 print_exit (refcook, defcook, symname, outregs->lrv_rax);
360
361 return 0;
362 }
363 #elif defined __sparc__ && !defined __arch64__
364 unsigned int
la_sparc32_gnu_pltexit(Elf32_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,const struct La_sparc32_regs * inregs,struct La_sparc32_retval * outregs,const char * symname)365 la_sparc32_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
366 uintptr_t *defcook, const struct La_sparc32_regs *inregs,
367 struct La_sparc32_retval *outregs, const char *symname)
368 {
369 print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
370
371 return 0;
372 }
373 #elif defined __sparc__ && defined __arch64__
374 unsigned int
la_sparc64_gnu_pltexit(Elf64_Sym * sym,unsigned int ndx,uintptr_t * refcook,uintptr_t * defcook,const struct La_sparc64_regs * inregs,struct La_sparc64_retval * outregs,const char * symname)375 la_sparc64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
376 uintptr_t *defcook, const struct La_sparc64_regs *inregs,
377 struct La_sparc64_retval *outregs, const char *symname)
378 {
379 print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
380
381 return 0;
382 }
383 #elif !defined HAVE_ARCH_PLTEXIT
384 # warning "pltexit for architecture not supported"
385 #endif
386