usr/src/cmd/truss/ipc.c

   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 2010 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <unistd.h>
  33 #include <ctype.h>
  34 #include <string.h>
  35 #include <signal.h>
  36 #include <stropts.h>
  37 #include <errno.h>
  38 #include <sys/types.h>
  39 #include <sys/termio.h>
  40 #include <libproc.h>
  41 #include "ramdata.h"
  42 #include "proto.h"
  43
  44 /*
  45  * Routines related to interprocess communication
  46  * among the truss processes which are controlling
  47  * multiple traced processes.
  48  */
  49
  50 /*
  51  * Function prototypes for static routines in this module.
  52  */
  53 void    Ecritical(int);
  54 void    Xcritical(int);
  55
  56 /*
  57  * Ensure everyone keeps out of each other's way
  58  * while writing lines of trace output.
  59  */
  60 void
  61 Flush()
  62 {
  63         /*
  64          * Except for regions bounded by Eserialize()/Xserialize(),
  65          * this is the only place anywhere in the program where a
  66          * write() to the trace output file takes place, so here
  67          * is where we detect errors writing to the output.
  68          */
  69
  70         errno = 0;
  71
  72         Ecritical(0);
  73         (void) fflush(stdout);
  74         Xcritical(0);
  75
  76         if (ferror(stdout) && errno)    /* error on write(), probably EPIPE */
  77                 interrupt = SIGTERM;            /* post an interrupt */
  78 }
  79
  80 /*
  81  * Eserialize() and Xserialize() are used to bracket
  82  * a region which may produce large amounts of output,
  83  * such as showargs()/dumpargs().
  84  */
  85
  86 void
  87 Eserialize()
  88 {
  89         /* serialize output */
  90         Ecritical(0);
  91 }
  92
  93 void
  94 Xserialize()
  95 {
  96         (void) fflush(stdout);
  97         Xcritical(0);
  98 }
  99
 100 /*
 101  * Enter critical region --- Wait on mutex, lock out other processes.
 102  * Lock zero is used to serialize output in situations where multiple processes
 103  * may be writing to stdout/stderr and order must be preserved.  Most of these
 104  * are in expound.c
 105  * Lock one is used to protect the table of processes currently being traced
 106  * every time a pid is added or removed from the table Ecritical(1)/Xcritical(1)
 107  * get called.
 108  */
 109 void
 110 Ecritical(int num)
 111 {
 112         int rv;
 113
 114         if (num == 0)
 115                 rv = mutex_lock(&gps->ps_mutex0);
 116         else if (num == 1)
 117                 rv = mutex_lock(&gps->ps_mutex1);
 118         else
 119                 abend("Invalid mutex specified", NULL);
 120
 121         if (rv != 0) {
 122                 char mnum[2];
 123                 mnum[0] = '0' + num;
 124                 mnum[1] = '\0';
 125                 errno = rv;
 126                 perror(command);
 127                 errmsg("cannot grab mutex #", mnum);
 128         }
 129 }
 130
 131 /*
 132  * Exit critical region ---
 133  * Release other processes waiting on mutex.
 134  */
 135 void
 136 Xcritical(int num)
 137 {
 138         int rv;
 139
 140         if (num == 0)
 141                 rv = mutex_unlock(&gps->ps_mutex0);
 142         else if (num == 1)
 143                 rv = mutex_unlock(&gps->ps_mutex1);
 144         else
 145                 abend("Invalid mutex specified", NULL);
 146
 147
 148         if (rv != 0) {
 149                 char mnum[2];
 150                 mnum[0] = '0' + num;
 151                 mnum[1] = '\0';
 152                 errno = rv;
 153                 perror(command);
 154                 errmsg("cannot release mutex #", mnum);
 155         }
 156 }
 157
 158 /*
 159  * Add process to set of those being traced.
 160  */
 161 void
 162 procadd(pid_t spid, const char *lwplist)
 163 {
 164         int i;
 165         int j = -1;
 166
 167         if (gps == NULL)
 168                 return;
 169
 170         Ecritical(1);
 171         for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
 172                 if (gps->tpid[i] == 0) {
 173                         if (j == -1)    /* remember first vacant slot */
 174                                 j = i;
 175                         if (gps->spid[i] == 0)  /* this slot is better */
 176                                 break;
 177                 }
 178         }
 179         if (i < sizeof (gps->tpid) / sizeof (gps->tpid[0]))
 180                 j = i;
 181         if (j >= 0) {
 182                 gps->tpid[j] = getpid();
 183                 gps->spid[j] = spid;
 184                 gps->lwps[j] = lwplist;
 185         }
 186         Xcritical(1);
 187 }
 188
 189 /*
 190  * Delete process from set of those being traced.
 191  */
 192 void
 193 procdel()
 194 {
 195         int i;
 196         pid_t tpid;
 197
 198         if (gps == NULL)
 199                 return;
 200
 201         tpid = getpid();
 202
 203         Ecritical(1);
 204         for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
 205                 if (gps->tpid[i] == tpid) {
 206                         gps->tpid[i] = 0;
 207                         break;
 208                 }
 209         }
 210         Xcritical(1);
 211 }
 212
 213 /*
 214  * Determine if the lwp for this process should be traced.
 215  */
 216 int
 217 lwptrace(pid_t spid, lwpid_t lwpid)
 218 {
 219         int i;
 220         pid_t tpid;
 221         const char *lwps;
 222
 223         if (gps == NULL)
 224                 return (0);
 225
 226         tpid = getpid();
 227
 228         Ecritical(1);
 229         for (i = 0; i < sizeof (gps->tpid) / sizeof (gps->tpid[0]); i++) {
 230                 if (gps->tpid[i] == tpid &&
 231                     gps->spid[i] == spid)
 232                         break;
 233         }
 234         lwps = gps->lwps[i];
 235         Xcritical(1);
 236
 237         return (proc_lwp_in_set(lwps, lwpid));
 238 }
 239
 240 /*
 241  * Check for open of a /proc/nnnnn file.
 242  * Return 0 if this is not an open of a /proc file.
 243  * Return 1 if the process opened itself.
 244  * Return 2 if the process failed to open another process
 245  * in truss's set of controlled processes.
 246  * Return 3 if the process successfully opened another process
 247  * in truss's set of controlled processes.
 248  * We notify and wait for the other controlling truss process
 249  * to terminate before returning in cases 2 and 3.
 250  */
 251 /* ARGSUSED */
 252 int
 253 checkproc(private_t *pri)
 254 {
 255         char *path = pri->sys_path;
 256         const pstatus_t *Psp = Pstatus(Proc);
 257         struct ps_lwphandle *Lwp = pri->Lwp;
 258         const lwpstatus_t *Lsp = pri->lwpstat;
 259         int what = Lsp->pr_what;        /* one of the SYS_open* syscalls */
 260         int err = Lsp->pr_errno;
 261         int pid;
 262         int i;
 263         const char *dirname;
 264         char *next;
 265         char *sp1;
 266         char *sp2;
 267         prgreg_t pc;
 268
 269         /*
 270          * A bit heuristic ...
 271          * Test for the cases:
 272          *      1234
 273          *      1234/as
 274          *      1234/ctl
 275          *      1234/lwp/24/lwpctl
 276          *      .../1234
 277          *      .../1234/as
 278          *      .../1234/ctl
 279          *      .../1234/lwp/24/lwpctl
 280          * Insert a '\0', if necessary, so the path becomes ".../1234".
 281          *
 282          * Along the way, watch out for /proc/self and /proc/1234/lwp/agent
 283          */
 284         if ((sp1 = strrchr(path, '/')) == NULL)         /* last component */
 285                 /* EMPTY */;
 286         else if (isdigit(*(sp1+1))) {
 287                 sp1 += strlen(sp1);
 288                 while (--sp1 > path && isdigit(*sp1))
 289                         ;
 290                 if (*sp1 != '/')
 291                         return (0);
 292         } else if (strcmp(sp1+1, "as") == 0 ||
 293             strcmp(sp1+1, "ctl") == 0) {
 294                 *sp1 = '\0';
 295         } else if (strcmp(sp1+1, "lwpctl") == 0) {
 296                 /*
 297                  * .../1234/lwp/24/lwpctl
 298                  * ............   ^-- sp1
 299                  */
 300                 if (sp1-6 >= path && strncmp(sp1-6, "/agent", 6) == 0)
 301                         sp1 -= 6;
 302                 else {
 303                         while (--sp1 > path && isdigit(*sp1))
 304                                 ;
 305                 }
 306                 if (*sp1 != '/' ||
 307                     (sp1 -= 4) <= path ||
 308                     strncmp(sp1, "/lwp", 4) != 0)
 309                         return (0);
 310                 *sp1 = '\0';
 311         } else if (strcmp(sp1+1, "self") != 0) {
 312                 return (0);
 313         }
 314
 315         if ((sp2 = strrchr(path, '/')) == NULL)
 316                 dirname = path;
 317         else
 318                 dirname = sp2 + 1;
 319
 320         if (strcmp(dirname, "self") == 0) {
 321                 pid = Psp->pr_pid;
 322         } else if ((pid = strtol(dirname, &next, 10)) < 0 ||
 323             *next != '\0') {    /* dirname not a number */
 324                 if (sp1 != NULL)
 325                         *sp1 = '/';
 326                 return (0);
 327         }
 328         if (sp2 == NULL)
 329                 dirname = ".";
 330         else {
 331                 *sp2 = '\0';
 332                 dirname = path;
 333         }
 334
 335         if (!Pisprocdir(Proc, dirname) || /* file not in a /proc directory */
 336             pid == getpid() ||          /* process opened truss's /proc file */
 337             pid == 0) {                 /* process opened process 0 */
 338                 if (sp1 != NULL)
 339                         *sp1 = '/';
 340                 if (sp2 != NULL)
 341                         *sp2 = '/';
 342                 return (0);
 343         }
 344         if (sp1 != NULL)
 345                 *sp1 = '/';
 346         if (sp2 != NULL)
 347                 *sp2 = '/';
 348
 349         /*
 350          * Process did open a /proc file ---
 351          */
 352         if (pid == Psp->pr_pid) {       /* process opened its own /proc file */
 353                 /*
 354                  * In SunOS 5.6 and beyond, self-opens always succeed.
 355                  */
 356                 return (1);
 357         }
 358
 359         /*
 360          * Search for a matching pid in our set of controlled processes.
 361          */
 362         for (i = 0; i < sizeof (gps->tpid)/sizeof (gps->tpid[0]); i++) {
 363                 if (gps->spid[i] == pid) {
 364                         pid = gps->tpid[i];
 365                         break;
 366                 }
 367         }
 368         if (i >= sizeof (gps->tpid) / sizeof (gps->tpid[0])) {
 369                 /*
 370                  * The process opened a /proc file, but not one we care about.
 371                  */
 372                 return (0);
 373         }
 374
 375         /*
 376          * Notify and wait for the controlling process to terminate.
 377          */
 378         while (pid && gps->tpid[i] == pid) {
 379                 if (kill(pid, SIGUSR1) == -1)
 380                         break;
 381                 (void) usleep(1000000);
 382         }
 383         Ecritical(1);
 384         if (gps->tpid[i] == 0)
 385                 gps->spid[i] = 0;
 386         Xcritical(1);
 387
 388         if (err) {      /* prepare to reissue the failed open() system call */
 389 #if defined(__sparc)
 390                 (void) Lgetareg(Lwp, R_PC, &pc);
 391                 if (pri->sys_indirect) {
 392                         (void) Lputareg(Lwp, R_G1, (prgreg_t)SYS_syscall);
 393                         (void) Lputareg(Lwp, R_O0, (prgreg_t)what);
 394                         for (i = 0; i < 5; i++)
 395                                 (void) Lputareg(Lwp, R_O1+i, pri->sys_args[i]);
 396                 } else {
 397                         (void) Lputareg(Lwp, R_G1, (prgreg_t)what);
 398                         for (i = 0; i < 6; i++)
 399                                 (void) Lputareg(Lwp, R_O0+i, pri->sys_args[i]);
 400                 }
 401                 (void) Lputareg(Lwp, R_nPC, pc);
 402 #elif defined(__amd64)
 403                 (void) Lgetareg(Lwp, R_PC, &pc);
 404                 (void) Lputareg(Lwp, REG_RAX, (prgreg_t)what);
 405 #elif defined(__i386)
 406                 (void) Lgetareg(Lwp, R_PC, &pc);
 407                 (void) Lputareg(Lwp, EAX, (prgreg_t)what);
 408 #else
 409 #error "unrecognized architecture"
 410 #endif
 411                 (void) Pissyscall_prev(Proc, pc, (uintptr_t *)&pc);
 412                 (void) Lputareg(Lwp, R_PC, pc);
 413                 return (2);
 414         }
 415
 416         return (3);
 417 }