elf/sotruss-lib.c

   1 /* Trace calls through PLTs and show caller, callee, and parameters.
   2    Copyright (C) 2011-2024 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 <err.h>
  20 #include <error.h>
  21 #include <fcntl.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/param.h>
  27 #include <sys/uio.h>
  28
  29 #include <ldsodefs.h>
  30
  31
  32 extern const char *__progname;
  33 extern const char *__progname_full;
  34
  35
  36 /* List of objects to trace calls from.  */
  37 static const char *fromlist;
  38 /* List of objects to trace calls to.  */
  39 static const char *tolist;
  40
  41 /* If non-zero, also trace returns of the calls.  */
  42 static int do_exit;
  43 /* If non-zero print PID for each line.  */
  44 static int print_pid;
  45
  46 /* The output stream to use.  */
  47 static FILE *out_file;
  48
  49
  50 static int
  51 match_pid (pid_t pid, const char *which)
  52 {
  53   if (which == NULL || which[0] == '\0')
  54     {
  55       print_pid = 1;
  56       return 1;
  57     }
  58
  59   char *endp;
  60   unsigned long n = strtoul (which, &endp, 0);
  61   return *endp == '\0' && n == pid;
  62 }
  63
  64
  65 static void
  66 init (void)
  67 {
  68   fromlist = getenv ("SOTRUSS_FROMLIST");
  69   if (fromlist != NULL && fromlist[0] == '\0')
  70     fromlist = NULL;
  71   tolist = getenv ("SOTRUSS_TOLIST");
  72   if (tolist != NULL && tolist[0] == '\0')
  73     tolist = NULL;
  74   do_exit = (getenv ("SOTRUSS_EXIT") ?: "")[0] != '\0';
  75
  76   /* Determine whether this process is supposed to be traced and if
  77      yes, whether we should print into a file.  */
  78   const char *which_process = getenv ("SOTRUSS_WHICH");
  79   pid_t pid = getpid ();
  80   int out_fd = -1;
  81   if (match_pid (pid, which_process))
  82     {
  83       const char *out_filename = getenv ("SOTRUSS_OUTNAME");
  84
  85       if (out_filename != NULL && out_filename[0] != 0)
  86         {
  87           size_t out_filename_len = strlen (out_filename) + 13;
  88           char fullname[out_filename_len];
  89           char *endp = stpcpy (fullname, out_filename);
  90           if (which_process == NULL || which_process[0] == '\0')
  91             snprintf (endp, 13, ".%ld", (long int) pid);
  92
  93           out_fd = open64 (fullname, O_RDWR | O_CREAT | O_TRUNC, 0666);
  94           if (out_fd != -1)
  95             print_pid = 0;
  96         }
  97     }
  98
  99   /* If we do not write into a file write to stderr.  Duplicate the
 100      descriptor so that we can keep printing in case the program
 101      closes stderr.  Try first to allocate a descriptor with a value
 102      usually not used as to minimize interference with the
 103      program.  */
 104   if (out_fd == -1)
 105     {
 106       out_fd = fcntl64 (STDERR_FILENO, F_DUPFD, 1000);
 107       if (out_fd == -1)
 108         out_fd = dup (STDERR_FILENO);
 109     }
 110
 111   if (out_fd != -1)
 112     {
 113       /* Convert file descriptor into a stream.  */
 114       out_file = fdopen (out_fd, "w");
 115       if (out_file != NULL)
 116         setlinebuf (out_file);
 117     }
 118 }
 119
 120
 121 /* Audit interface verification.  We also initialize everything if
 122    everything checks out OK.  */
 123 unsigned int
 124 la_version (unsigned int v)
 125 {
 126   if (v != LAV_CURRENT)
 127     error (1, 0, "cannot handle interface version %u", v);
 128
 129   init ();
 130
 131   return v;
 132 }
 133
 134
 135 /* Check whether a file name is on the colon-separated list of file
 136    names.  */
 137 static unsigned int
 138 match_file (const char *list, const char *name, size_t name_len,
 139             unsigned int mask)
 140 {
 141   if (list[0] == '\0')
 142     return 0;
 143
 144   const char *cp = list;
 145   while (1)
 146     {
 147       if (strncmp (cp, name, name_len) == 0
 148           && (cp[name_len] == ':' || cp[name_len] == '\0'))
 149         return mask;
 150
 151       cp = strchr (cp, ':');
 152       if (cp == NULL)
 153         return 0;
 154       ++cp;
 155     }
 156 }
 157
 158
 159 unsigned int
 160 la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
 161 {
 162   if (out_file == NULL)
 163     return 0;
 164
 165   const char *full_name = map->l_name ?: "";
 166   if (full_name[0] == '\0')
 167     full_name = __progname_full;
 168   size_t full_name_len = strlen (full_name);
 169   const char *base_name = basename (full_name);
 170   if (base_name[0] == '\0')
 171     base_name = __progname;
 172   size_t base_name_len = strlen (base_name);
 173
 174   int result = 0;
 175   const char *print_name = NULL;
 176   for (struct libname_list *l = map->l_libname; l != NULL; l = l->next)
 177     {
 178       if (print_name == NULL || (print_name[0] == '/' && l->name[0] != '/'))
 179         print_name = l->name;
 180
 181       if (fromlist != NULL)
 182         result |= match_file (fromlist, l->name, strlen (l->name),
 183                               LA_FLG_BINDFROM);
 184
 185       if (tolist != NULL)
 186         result |= match_file (tolist, l->name, strlen (l->name),LA_FLG_BINDTO);
 187     }
 188
 189   if (print_name == NULL)
 190     print_name = base_name;
 191   if (print_name[0] == '\0')
 192     print_name = __progname;
 193
 194   /* We cannot easily get to the object name in the PLT handling
 195      functions.  Use the cookie to get the string pointer passed back
 196      to us.  */
 197   *cookie = (uintptr_t) print_name;
 198
 199   /* The object name has to be on the list of objects to trace calls
 200      from or that list must be empty.  In the latter case we trace
 201      only calls from the main binary.  */
 202   if (fromlist == NULL)
 203     result |= map->l_name[0] == '\0' ? LA_FLG_BINDFROM : 0;
 204   else
 205     result |= (match_file (fromlist, full_name, full_name_len,
 206                            LA_FLG_BINDFROM)
 207                | match_file (fromlist, base_name, base_name_len,
 208                              LA_FLG_BINDFROM));
 209
 210   /* The object name has to be on the list of objects to trace calls
 211      to or that list must be empty.  In the latter case we trace
 212      calls toall objects.  */
 213   if (tolist == NULL)
 214     result |= LA_FLG_BINDTO;
 215   else
 216     result |= (match_file (tolist, full_name, full_name_len, LA_FLG_BINDTO)
 217                | match_file (tolist, base_name, base_name_len, LA_FLG_BINDTO));
 218
 219   return result;
 220 }
 221
 222
 223 #if __ELF_NATIVE_CLASS == 32
 224 # define la_symbind la_symbind32
 225 typedef Elf32_Sym Elf_Sym;
 226 #else
 227 # define la_symbind la_symbind64
 228 typedef Elf64_Sym Elf_Sym;
 229 #endif
 230
 231 uintptr_t
 232 la_symbind (Elf_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 233             uintptr_t *defcook, unsigned int *flags, const char *symname)
 234 {
 235   if (*flags & LA_SYMB_NOPLTENTER)
 236     warnx ("cannot trace PLT enter (bind-now enabled)");
 237
 238   if (do_exit && *flags & LA_SYMB_NOPLTEXIT)
 239     warnx ("cannot trace PLT exit (bind-now enabled)");
 240
 241   if (!do_exit)
 242     *flags = LA_SYMB_NOPLTEXIT;
 243
 244   return sym->st_value;
 245 }
 246
 247
 248 static void
 249 print_enter (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
 250              unsigned long int reg1, unsigned long int reg2,
 251              unsigned long int reg3, unsigned int flags)
 252 {
 253   char buf[3 * sizeof (pid_t) + 3];
 254   buf[0] = '\0';
 255   if (print_pid)
 256     snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
 257
 258   fprintf (out_file, "%s%15s -> %-15s:%s%s(0x%lx, 0x%lx, 0x%lx)\n",
 259            buf, (char *) *refcook, (char *) *defcook,
 260            (flags & LA_SYMB_NOPLTEXIT) ? "*" : " ", symname, reg1, reg2, reg3);
 261 }
 262
 263
 264 #ifdef __i386__
 265 Elf32_Addr
 266 la_i86_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
 267                      unsigned int ndx __attribute__ ((unused)),
 268                      uintptr_t *refcook, uintptr_t *defcook,
 269                      La_i86_regs *regs, unsigned int *flags,
 270                      const char *symname, long int *framesizep)
 271 {
 272   unsigned long int *sp = (unsigned long int *) regs->lr_esp;
 273
 274   print_enter (refcook, defcook, symname, sp[1], sp[2], sp[3], *flags);
 275
 276   /* No need to copy anything, we will not need the parameters in any case.  */
 277   *framesizep = 0;
 278
 279   return sym->st_value;
 280 }
 281 #elif defined __x86_64__
 282 Elf64_Addr
 283 la_x86_64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
 284                         unsigned int ndx __attribute__ ((unused)),
 285                         uintptr_t *refcook, uintptr_t *defcook,
 286                         La_x86_64_regs *regs, unsigned int *flags,
 287                         const char *symname, long int *framesizep)
 288 {
 289   print_enter (refcook, defcook, symname,
 290                regs->lr_rdi, regs->lr_rsi, regs->lr_rdx, *flags);
 291
 292   /* No need to copy anything, we will not need the parameters in any case.  */
 293   *framesizep = 0;
 294
 295   return sym->st_value;
 296 }
 297 #elif defined __sparc__ && !defined __arch64__
 298 Elf32_Addr
 299 la_sparc32_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
 300                          unsigned int ndx __attribute__ ((unused)),
 301                          uintptr_t *refcook, uintptr_t *defcook,
 302                          La_sparc32_regs *regs, unsigned int *flags,
 303                          const char *symname, long int *framesizep)
 304 {
 305   print_enter (refcook, defcook, symname,
 306                regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
 307                *flags);
 308
 309   /* No need to copy anything, we will not need the parameters in any case.  */
 310   *framesizep = 0;
 311
 312   return sym->st_value;
 313 }
 314 #elif defined __sparc__ && defined __arch64__
 315 Elf64_Addr
 316 la_sparc64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
 317                          unsigned int ndx __attribute__ ((unused)),
 318                          uintptr_t *refcook, uintptr_t *defcook,
 319                          La_sparc64_regs *regs, unsigned int *flags,
 320                          const char *symname, long int *framesizep)
 321 {
 322   print_enter (refcook, defcook, symname,
 323                regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
 324                *flags);
 325
 326   /* No need to copy anything, we will not need the parameters in any case.  */
 327   *framesizep = 0;
 328
 329   return sym->st_value;
 330 }
 331 #elif !defined HAVE_ARCH_PLTENTER
 332 # warning "pltenter for architecture not supported"
 333 #endif
 334
 335
 336 static void
 337 print_exit (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
 338             unsigned long int reg)
 339 {
 340   char buf[3 * sizeof (pid_t) + 3];
 341   buf[0] = '\0';
 342   if (print_pid)
 343     snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
 344
 345   fprintf (out_file, "%s%15s -> %-15s:%s%s - 0x%lx\n",
 346            buf, (char *) *refcook, (char *) *defcook, " ", symname, reg);
 347 }
 348
 349
 350 #ifdef __i386__
 351 unsigned int
 352 la_i86_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 353                     uintptr_t *defcook, const struct La_i86_regs *inregs,
 354                     struct La_i86_retval *outregs, const char *symname)
 355 {
 356   print_exit (refcook, defcook, symname, outregs->lrv_eax);
 357
 358   return 0;
 359 }
 360 #elif defined __x86_64__
 361 unsigned int
 362 la_x86_64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 363                        uintptr_t *defcook, const struct La_x86_64_regs *inregs,
 364                        struct La_x86_64_retval *outregs, const char *symname)
 365 {
 366   print_exit (refcook, defcook, symname, outregs->lrv_rax);
 367
 368   return 0;
 369 }
 370 #elif defined __sparc__ && !defined __arch64__
 371 unsigned int
 372 la_sparc32_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 373                         uintptr_t *defcook, const struct La_sparc32_regs *inregs,
 374                         struct La_sparc32_retval *outregs, const char *symname)
 375 {
 376   print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
 377
 378   return 0;
 379 }
 380 #elif defined __sparc__ && defined __arch64__
 381 unsigned int
 382 la_sparc64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 383                         uintptr_t *defcook, const struct La_sparc64_regs *inregs,
 384                         struct La_sparc64_retval *outregs, const char *symname)
 385 {
 386   print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
 387
 388   return 0;
 389 }
 390 #elif !defined HAVE_ARCH_PLTEXIT
 391 # warning "pltexit for architecture not supported"
 392 #endif