elf/sotruss-lib.c

   1 /* Trace calls through PLTs and show caller, callee, and parameters.
   2    Copyright (C) 2011-2022 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
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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