elf/sotruss-lib.c

   1 /* Trace calls through PLTs and show caller, callee, and parameters.
   2    Copyright (C) 2011-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  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 = open (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 = fcntl (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 (!do_exit)
 236     *flags = LA_SYMB_NOPLTEXIT;
 237
 238   return sym->st_value;
 239 }
 240
 241
 242 static void
 243 print_enter (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
 244              unsigned long int reg1, unsigned long int reg2,
 245              unsigned long int reg3, unsigned int flags)
 246 {
 247   char buf[3 * sizeof (pid_t) + 3];
 248   buf[0] = '\0';
 249   if (print_pid)
 250     snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
 251
 252   fprintf (out_file, "%s%15s -> %-15s:%s%s(0x%lx, 0x%lx, 0x%lx)\n",
 253            buf, (char *) *refcook, (char *) *defcook,
 254            (flags & LA_SYMB_NOPLTEXIT) ? "*" : " ", symname, reg1, reg2, reg3);
 255 }
 256
 257
 258 #ifdef __i386__
 259 Elf32_Addr
 260 la_i86_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
 261                      unsigned int ndx __attribute__ ((unused)),
 262                      uintptr_t *refcook, uintptr_t *defcook,
 263                      La_i86_regs *regs, unsigned int *flags,
 264                      const char *symname, long int *framesizep)
 265 {
 266   unsigned long int *sp = (unsigned long int *) regs->lr_esp;
 267
 268   print_enter (refcook, defcook, symname, sp[1], sp[2], sp[3], *flags);
 269
 270   /* No need to copy anything, we will not need the parameters in any case.  */
 271   *framesizep = 0;
 272
 273   return sym->st_value;
 274 }
 275 #elif defined __x86_64__
 276 Elf64_Addr
 277 la_x86_64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
 278                         unsigned int ndx __attribute__ ((unused)),
 279                         uintptr_t *refcook, uintptr_t *defcook,
 280                         La_x86_64_regs *regs, unsigned int *flags,
 281                         const char *symname, long int *framesizep)
 282 {
 283   print_enter (refcook, defcook, symname,
 284                regs->lr_rdi, regs->lr_rsi, regs->lr_rdx, *flags);
 285
 286   /* No need to copy anything, we will not need the parameters in any case.  */
 287   *framesizep = 0;
 288
 289   return sym->st_value;
 290 }
 291 #elif defined __sparc__ && !defined __arch64__
 292 Elf32_Addr
 293 la_sparc32_gnu_pltenter (Elf32_Sym *sym __attribute__ ((unused)),
 294                          unsigned int ndx __attribute__ ((unused)),
 295                          uintptr_t *refcook, uintptr_t *defcook,
 296                          La_sparc32_regs *regs, unsigned int *flags,
 297                          const char *symname, long int *framesizep)
 298 {
 299   print_enter (refcook, defcook, symname,
 300                regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
 301                *flags);
 302
 303   /* No need to copy anything, we will not need the parameters in any case.  */
 304   *framesizep = 0;
 305
 306   return sym->st_value;
 307 }
 308 #elif defined __sparc__ && defined __arch64__
 309 Elf64_Addr
 310 la_sparc64_gnu_pltenter (Elf64_Sym *sym __attribute__ ((unused)),
 311                          unsigned int ndx __attribute__ ((unused)),
 312                          uintptr_t *refcook, uintptr_t *defcook,
 313                          La_sparc64_regs *regs, unsigned int *flags,
 314                          const char *symname, long int *framesizep)
 315 {
 316   print_enter (refcook, defcook, symname,
 317                regs->lr_reg[0], regs->lr_reg[1], regs->lr_reg[2],
 318                *flags);
 319
 320   /* No need to copy anything, we will not need the parameters in any case.  */
 321   *framesizep = 0;
 322
 323   return sym->st_value;
 324 }
 325 #elif !defined HAVE_ARCH_PLTENTER
 326 # warning "pltenter for architecture not supported"
 327 #endif
 328
 329
 330 static void
 331 print_exit (uintptr_t *refcook, uintptr_t *defcook, const char *symname,
 332             unsigned long int reg)
 333 {
 334   char buf[3 * sizeof (pid_t) + 3];
 335   buf[0] = '\0';
 336   if (print_pid)
 337     snprintf (buf, sizeof (buf), "%5ld: ", (long int) getpid ());
 338
 339   fprintf (out_file, "%s%15s -> %-15s:%s%s - 0x%lx\n",
 340            buf, (char *) *refcook, (char *) *defcook, " ", symname, reg);
 341 }
 342
 343
 344 #ifdef __i386__
 345 unsigned int
 346 la_i86_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 347                     uintptr_t *defcook, const struct La_i86_regs *inregs,
 348                     struct La_i86_retval *outregs, const char *symname)
 349 {
 350   print_exit (refcook, defcook, symname, outregs->lrv_eax);
 351
 352   return 0;
 353 }
 354 #elif defined __x86_64__
 355 unsigned int
 356 la_x86_64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 357                        uintptr_t *defcook, const struct La_x86_64_regs *inregs,
 358                        struct La_x86_64_retval *outregs, const char *symname)
 359 {
 360   print_exit (refcook, defcook, symname, outregs->lrv_rax);
 361
 362   return 0;
 363 }
 364 #elif defined __sparc__ && !defined __arch64__
 365 unsigned int
 366 la_sparc32_gnu_pltexit (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 367                         uintptr_t *defcook, const struct La_sparc32_regs *inregs,
 368                         struct La_sparc32_retval *outregs, const char *symname)
 369 {
 370   print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
 371
 372   return 0;
 373 }
 374 #elif defined __sparc__ && defined __arch64__
 375 unsigned int
 376 la_sparc64_gnu_pltexit (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook,
 377                         uintptr_t *defcook, const struct La_sparc64_regs *inregs,
 378                         struct La_sparc64_retval *outregs, const char *symname)
 379 {
 380   print_exit (refcook, defcook, symname, outregs->lrv_reg[0]);
 381
 382   return 0;
 383 }
 384 #elif !defined HAVE_ARCH_PLTEXIT
 385 # warning "pltexit for architecture not supported"
 386 #endif