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 (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
  24  */
  25 
  26 /*      Copyright (c) 1988 AT&T     */
  27 /*        All Rights Reserved   */
  28 /*
  29  * Copyright 2014, Joyent, Inc.  All rights reserved.
  30  */
  31 
  32 #include <sys/types.h>
  33 #include <sys/param.h>
  34 #include <sys/sysmacros.h>
  35 #include <sys/systm.h>
  36 #include <sys/signal.h>
  37 #include <sys/cred_impl.h>
  38 #include <sys/policy.h>
  39 #include <sys/user.h>
  40 #include <sys/errno.h>
  41 #include <sys/file.h>
  42 #include <sys/vfs.h>
  43 #include <sys/vnode.h>
  44 #include <sys/mman.h>
  45 #include <sys/acct.h>
  46 #include <sys/cpuvar.h>
  47 #include <sys/proc.h>
  48 #include <sys/cmn_err.h>
  49 #include <sys/debug.h>
  50 #include <sys/pathname.h>
  51 #include <sys/vm.h>
  52 #include <sys/lgrp.h>
  53 #include <sys/vtrace.h>
  54 #include <sys/exec.h>
  55 #include <sys/exechdr.h>
  56 #include <sys/kmem.h>
  57 #include <sys/prsystm.h>
  58 #include <sys/modctl.h>
  59 #include <sys/vmparam.h>
  60 #include <sys/door.h>
  61 #include <sys/schedctl.h>
  62 #include <sys/utrap.h>
  63 #include <sys/systeminfo.h>
  64 #include <sys/stack.h>
  65 #include <sys/rctl.h>
  66 #include <sys/dtrace.h>
  67 #include <sys/lwpchan_impl.h>
  68 #include <sys/pool.h>
  69 #include <sys/sdt.h>
  70 #include <sys/brand.h>
  71 #include <sys/klpd.h>
  72 #include <sys/random.h>
  73 
  74 #include <c2/audit.h>
  75 
  76 #include <vm/hat.h>
  77 #include <vm/anon.h>
  78 #include <vm/as.h>
  79 #include <vm/seg.h>
  80 #include <vm/seg_vn.h>
  81 
  82 #define PRIV_RESET              0x01    /* needs to reset privs */
  83 #define PRIV_SETID              0x02    /* needs to change uids */
  84 #define PRIV_SETUGID            0x04    /* is setuid/setgid/forced privs */
  85 #define PRIV_INCREASE           0x08    /* child runs with more privs */
  86 #define MAC_FLAGS               0x10    /* need to adjust MAC flags */
  87 #define PRIV_FORCED             0x20    /* has forced privileges */
  88 
  89 static int execsetid(struct vnode *, struct vattr *, uid_t *, uid_t *,
  90     priv_set_t *, cred_t *, const char *);
  91 static int hold_execsw(struct execsw *);
  92 
  93 uint_t auxv_hwcap = 0;  /* auxv AT_SUN_HWCAP value; determined on the fly */
  94 uint_t auxv_hwcap_2 = 0;        /* AT_SUN_HWCAP2 */
  95 #if defined(_SYSCALL32_IMPL)
  96 uint_t auxv_hwcap32 = 0;        /* 32-bit version of auxv_hwcap */
  97 uint_t auxv_hwcap32_2 = 0;      /* 32-bit version of auxv_hwcap2 */
  98 #endif
  99 
 100 #define PSUIDFLAGS              (SNOCD|SUGID)
 101 
 102 /*
 103  * These are consumed within the specific exec modules, but are defined here because
 104  *
 105  * 1) The exec modules are unloadable, which would make this near useless.
 106  *
 107  * 2) We want them to be common across all of them, should more than ELF come
 108  *    to support them.
 109  *
 110  * All must be powers of 2.
 111  */
 112 volatile size_t aslr_max_brk_skew = 16 * 1024 * 1024; /* 16MB */
 113 #pragma weak exec_stackgap = aslr_max_stack_skew      /* Old, compatible name */
 114 volatile size_t aslr_max_stack_skew = 64 * 1024;      /* 64KB */
 115 
 116 /*
 117  * exece() - system call wrapper around exec_common()
 118  */
 119 int
 120 exece(const char *fname, const char **argp, const char **envp)
 121 {
 122         int error;
 123 
 124         error = exec_common(fname, argp, envp, EBA_NONE);
 125         return (error ? (set_errno(error)) : 0);
 126 }
 127 
 128 int
 129 exec_common(const char *fname, const char **argp, const char **envp,
 130     int brand_action)
 131 {
 132         vnode_t *vp = NULL, *dir = NULL, *tmpvp = NULL;
 133         proc_t *p = ttoproc(curthread);
 134         klwp_t *lwp = ttolwp(curthread);
 135         struct user *up = PTOU(p);
 136         long execsz;            /* temporary count of exec size */
 137         int i;
 138         int error;
 139         char exec_file[MAXCOMLEN+1];
 140         struct pathname pn;
 141         struct pathname resolvepn;
 142         struct uarg args;
 143         struct execa ua;
 144         k_sigset_t savedmask;
 145         lwpdir_t *lwpdir = NULL;
 146         tidhash_t *tidhash;
 147         lwpdir_t *old_lwpdir = NULL;
 148         uint_t old_lwpdir_sz;
 149         tidhash_t *old_tidhash;
 150         uint_t old_tidhash_sz;
 151         ret_tidhash_t *ret_tidhash;
 152         lwpent_t *lep;
 153         boolean_t brandme = B_FALSE;
 154 
 155         /*
 156          * exec() is not supported for the /proc agent lwp.
 157          */
 158         if (curthread == p->p_agenttp)
 159                 return (ENOTSUP);
 160 
 161         if (brand_action != EBA_NONE) {
 162                 /*
 163                  * Brand actions are not supported for processes that are not
 164                  * running in a branded zone.
 165                  */
 166                 if (!ZONE_IS_BRANDED(p->p_zone))
 167                         return (ENOTSUP);
 168 
 169                 if (brand_action == EBA_NATIVE) {
 170                         /* Only branded processes can be unbranded */
 171                         if (!PROC_IS_BRANDED(p))
 172                                 return (ENOTSUP);
 173                 } else {
 174                         /* Only unbranded processes can be branded */
 175                         if (PROC_IS_BRANDED(p))
 176                                 return (ENOTSUP);
 177                         brandme = B_TRUE;
 178                 }
 179         } else {
 180                 /*
 181                  * If this is a native zone, or if the process is already
 182                  * branded, then we don't need to do anything.  If this is
 183                  * a native process in a branded zone, we need to brand the
 184                  * process as it exec()s the new binary.
 185                  */
 186                 if (ZONE_IS_BRANDED(p->p_zone) && !PROC_IS_BRANDED(p))
 187                         brandme = B_TRUE;
 188         }
 189 
 190         /*
 191          * Inform /proc that an exec() has started.
 192          * Hold signals that are ignored by default so that we will
 193          * not be interrupted by a signal that will be ignored after
 194          * successful completion of gexec().
 195          */
 196         mutex_enter(&p->p_lock);
 197         prexecstart();
 198         schedctl_finish_sigblock(curthread);
 199         savedmask = curthread->t_hold;
 200         sigorset(&curthread->t_hold, &ignoredefault);
 201         mutex_exit(&p->p_lock);
 202 
 203         /*
 204          * Look up path name and remember last component for later.
 205          * To help coreadm expand its %d token, we attempt to save
 206          * the directory containing the executable in p_execdir. The
 207          * first call to lookuppn() may fail and return EINVAL because
 208          * dirvpp is non-NULL. In that case, we make a second call to
 209          * lookuppn() with dirvpp set to NULL; p_execdir will be NULL,
 210          * but coreadm is allowed to expand %d to the empty string and
 211          * there are other cases in which that failure may occur.
 212          */
 213         if ((error = pn_get((char *)fname, UIO_USERSPACE, &pn)) != 0)
 214                 goto out;
 215         pn_alloc(&resolvepn);
 216         if ((error = lookuppn(&pn, &resolvepn, FOLLOW, &dir, &vp)) != 0) {
 217                 pn_free(&resolvepn);
 218                 pn_free(&pn);
 219                 if (error != EINVAL)
 220                         goto out;
 221 
 222                 dir = NULL;
 223                 if ((error = pn_get((char *)fname, UIO_USERSPACE, &pn)) != 0)
 224                         goto out;
 225                 pn_alloc(&resolvepn);
 226                 if ((error = lookuppn(&pn, &resolvepn, FOLLOW, NULLVPP,
 227                     &vp)) != 0) {
 228                         pn_free(&resolvepn);
 229                         pn_free(&pn);
 230                         goto out;
 231                 }
 232         }
 233         if (vp == NULL) {
 234                 if (dir != NULL)
 235                         VN_RELE(dir);
 236                 error = ENOENT;
 237                 pn_free(&resolvepn);
 238                 pn_free(&pn);
 239                 goto out;
 240         }
 241 
 242         if ((error = secpolicy_basic_exec(CRED(), vp)) != 0) {
 243                 if (dir != NULL)
 244                         VN_RELE(dir);
 245                 pn_free(&resolvepn);
 246                 pn_free(&pn);
 247                 VN_RELE(vp);
 248                 goto out;
 249         }
 250 
 251         /*
 252          * We do not allow executing files in attribute directories.
 253          * We test this by determining whether the resolved path
 254          * contains a "/" when we're in an attribute directory;
 255          * only if the pathname does not contain a "/" the resolved path
 256          * points to a file in the current working (attribute) directory.
 257          */
 258         if ((p->p_user.u_cdir->v_flag & V_XATTRDIR) != 0 &&
 259             strchr(resolvepn.pn_path, '/') == NULL) {
 260                 if (dir != NULL)
 261                         VN_RELE(dir);
 262                 error = EACCES;
 263                 pn_free(&resolvepn);
 264                 pn_free(&pn);
 265                 VN_RELE(vp);
 266                 goto out;
 267         }
 268 
 269         bzero(exec_file, MAXCOMLEN+1);
 270         (void) strncpy(exec_file, pn.pn_path, MAXCOMLEN);
 271         bzero(&args, sizeof (args));
 272         args.pathname = resolvepn.pn_path;
 273         /* don't free resolvepn until we are done with args */
 274         pn_free(&pn);
 275 
 276         /*
 277          * If we're running in a profile shell, then call pfexecd.
 278          */
 279         if ((CR_FLAGS(p->p_cred) & PRIV_PFEXEC) != 0) {
 280                 error = pfexec_call(p->p_cred, &resolvepn, &args.pfcred,
 281                     &args.scrubenv);
 282 
 283                 /* Returning errno in case we're not allowed to execute. */
 284                 if (error > 0) {
 285                         if (dir != NULL)
 286                                 VN_RELE(dir);
 287                         pn_free(&resolvepn);
 288                         VN_RELE(vp);
 289                         goto out;
 290                 }
 291 
 292                 /* Don't change the credentials when using old ptrace. */
 293                 if (args.pfcred != NULL &&
 294                     (p->p_proc_flag & P_PR_PTRACE) != 0) {
 295                         crfree(args.pfcred);
 296                         args.pfcred = NULL;
 297                         args.scrubenv = B_FALSE;
 298                 }
 299         }
 300 
 301         /*
 302          * Specific exec handlers, or policies determined via
 303          * /etc/system may override the historical default.
 304          */
 305         args.stk_prot = PROT_ZFOD;
 306         args.dat_prot = PROT_ZFOD;
 307 
 308         CPU_STATS_ADD_K(sys, sysexec, 1);
 309         DTRACE_PROC1(exec, char *, args.pathname);
 310 
 311         ua.fname = fname;
 312         ua.argp = argp;
 313         ua.envp = envp;
 314 
 315         /* If necessary, brand this process before we start the exec. */
 316         if (brandme)
 317                 brand_setbrand(p);
 318 
 319         if ((error = gexec(&vp, &ua, &args, NULL, 0, &execsz,
 320             exec_file, p->p_cred, brand_action)) != 0) {
 321                 if (brandme)
 322                         brand_clearbrand(p, B_FALSE);
 323                 VN_RELE(vp);
 324                 if (dir != NULL)
 325                         VN_RELE(dir);
 326                 pn_free(&resolvepn);
 327                 goto fail;
 328         }
 329 
 330         /*
 331          * Free floating point registers (sun4u only)
 332          */
 333         ASSERT(lwp != NULL);
 334         lwp_freeregs(lwp, 1);
 335 
 336         /*
 337          * Free thread and process context ops.
 338          */
 339         if (curthread->t_ctx)
 340                 freectx(curthread, 1);
 341         if (p->p_pctx)
 342                 freepctx(p, 1);
 343 
 344         /*
 345          * Remember file name for accounting; clear any cached DTrace predicate.
 346          */
 347         up->u_acflag &= ~AFORK;
 348         bcopy(exec_file, up->u_comm, MAXCOMLEN+1);
 349         curthread->t_predcache = NULL;
 350 
 351         /*
 352          * Clear contract template state
 353          */
 354         lwp_ctmpl_clear(lwp);
 355 
 356         /*
 357          * Save the directory in which we found the executable for expanding
 358          * the %d token used in core file patterns.
 359          */
 360         mutex_enter(&p->p_lock);
 361         tmpvp = p->p_execdir;
 362         p->p_execdir = dir;
 363         if (p->p_execdir != NULL)
 364                 VN_HOLD(p->p_execdir);
 365         mutex_exit(&p->p_lock);
 366 
 367         if (tmpvp != NULL)
 368                 VN_RELE(tmpvp);
 369 
 370         /*
 371          * Reset stack state to the user stack, clear set of signals
 372          * caught on the signal stack, and reset list of signals that
 373          * restart system calls; the new program's environment should
 374          * not be affected by detritus from the old program.  Any
 375          * pending held signals remain held, so don't clear t_hold.
 376          */
 377         mutex_enter(&p->p_lock);
 378         lwp->lwp_oldcontext = 0;
 379         lwp->lwp_ustack = 0;
 380         lwp->lwp_old_stk_ctl = 0;
 381         sigemptyset(&up->u_signodefer);
 382         sigemptyset(&up->u_sigonstack);
 383         sigemptyset(&up->u_sigresethand);
 384         lwp->lwp_sigaltstack.ss_sp = 0;
 385         lwp->lwp_sigaltstack.ss_size = 0;
 386         lwp->lwp_sigaltstack.ss_flags = SS_DISABLE;
 387 
 388         /*
 389          * Make saved resource limit == current resource limit.
 390          */
 391         for (i = 0; i < RLIM_NLIMITS; i++) {
 392                 /*CONSTCOND*/
 393                 if (RLIM_SAVED(i)) {
 394                         (void) rctl_rlimit_get(rctlproc_legacy[i], p,
 395                             &up->u_saved_rlimit[i]);
 396                 }
 397         }
 398 
 399         /*
 400          * If the action was to catch the signal, then the action
 401          * must be reset to SIG_DFL.
 402          */
 403         sigdefault(p);
 404         p->p_flag &= ~(SNOWAIT|SJCTL);
 405         p->p_flag |= (SEXECED|SMSACCT|SMSFORK);
 406         up->u_signal[SIGCLD - 1] = SIG_DFL;
 407 
 408         /*
 409          * Delete the dot4 sigqueues/signotifies.
 410          */
 411         sigqfree(p);
 412 
 413         mutex_exit(&p->p_lock);
 414 
 415         mutex_enter(&p->p_pflock);
 416         p->p_prof.pr_base = NULL;
 417         p->p_prof.pr_size = 0;
 418         p->p_prof.pr_off = 0;
 419         p->p_prof.pr_scale = 0;
 420         p->p_prof.pr_samples = 0;
 421         mutex_exit(&p->p_pflock);
 422 
 423         ASSERT(curthread->t_schedctl == NULL);
 424 
 425 #if defined(__sparc)
 426         if (p->p_utraps != NULL)
 427                 utrap_free(p);
 428 #endif  /* __sparc */
 429 
 430         /*
 431          * Close all close-on-exec files.
 432          */
 433         close_exec(P_FINFO(p));
 434         TRACE_2(TR_FAC_PROC, TR_PROC_EXEC, "proc_exec:p %p up %p", p, up);
 435 
 436         /* Unbrand ourself if necessary. */
 437         if (PROC_IS_BRANDED(p) && (brand_action == EBA_NATIVE))
 438                 brand_clearbrand(p, B_FALSE);
 439 
 440         setregs(&args);
 441 
 442         /* Mark this as an executable vnode */
 443         mutex_enter(&vp->v_lock);
 444         vp->v_flag |= VVMEXEC;
 445         mutex_exit(&vp->v_lock);
 446 
 447         VN_RELE(vp);
 448         if (dir != NULL)
 449                 VN_RELE(dir);
 450         pn_free(&resolvepn);
 451 
 452         /*
 453          * Allocate a new lwp directory and lwpid hash table if necessary.
 454          */
 455         if (curthread->t_tid != 1 || p->p_lwpdir_sz != 2) {
 456                 lwpdir = kmem_zalloc(2 * sizeof (lwpdir_t), KM_SLEEP);
 457                 lwpdir->ld_next = lwpdir + 1;
 458                 tidhash = kmem_zalloc(2 * sizeof (tidhash_t), KM_SLEEP);
 459                 if (p->p_lwpdir != NULL)
 460                         lep = p->p_lwpdir[curthread->t_dslot].ld_entry;
 461                 else
 462                         lep = kmem_zalloc(sizeof (*lep), KM_SLEEP);
 463         }
 464 
 465         if (PROC_IS_BRANDED(p))
 466                 BROP(p)->b_exec();
 467 
 468         mutex_enter(&p->p_lock);
 469         prbarrier(p);
 470 
 471         /*
 472          * Reset lwp id to the default value of 1.
 473          * This is a single-threaded process now
 474          * and lwp #1 is lwp_wait()able by default.
 475          * The t_unpark flag should not be inherited.
 476          */
 477         ASSERT(p->p_lwpcnt == 1 && p->p_zombcnt == 0);
 478         curthread->t_tid = 1;
 479         kpreempt_disable();
 480         ASSERT(curthread->t_lpl != NULL);
 481         p->p_t1_lgrpid = curthread->t_lpl->lpl_lgrpid;
 482         kpreempt_enable();
 483         if (p->p_tr_lgrpid != LGRP_NONE && p->p_tr_lgrpid != p->p_t1_lgrpid) {
 484                 lgrp_update_trthr_migrations(1);
 485         }
 486         curthread->t_unpark = 0;
 487         curthread->t_proc_flag |= TP_TWAIT;
 488         curthread->t_proc_flag &= ~TP_DAEMON;    /* daemons shouldn't exec */
 489         p->p_lwpdaemon = 0;                  /* but oh well ... */
 490         p->p_lwpid = 1;
 491 
 492         /*
 493          * Install the newly-allocated lwp directory and lwpid hash table
 494          * and insert the current thread into the new hash table.
 495          */
 496         if (lwpdir != NULL) {
 497                 old_lwpdir = p->p_lwpdir;
 498                 old_lwpdir_sz = p->p_lwpdir_sz;
 499                 old_tidhash = p->p_tidhash;
 500                 old_tidhash_sz = p->p_tidhash_sz;
 501                 p->p_lwpdir = p->p_lwpfree = lwpdir;
 502                 p->p_lwpdir_sz = 2;
 503                 lep->le_thread = curthread;
 504                 lep->le_lwpid = curthread->t_tid;
 505                 lep->le_start = curthread->t_start;
 506                 lwp_hash_in(p, lep, tidhash, 2, 0);
 507                 p->p_tidhash = tidhash;
 508                 p->p_tidhash_sz = 2;
 509         }
 510         ret_tidhash = p->p_ret_tidhash;
 511         p->p_ret_tidhash = NULL;
 512 
 513         /*
 514          * Restore the saved signal mask and
 515          * inform /proc that the exec() has finished.
 516          */
 517         curthread->t_hold = savedmask;
 518         prexecend();
 519         mutex_exit(&p->p_lock);
 520         if (old_lwpdir) {
 521                 kmem_free(old_lwpdir, old_lwpdir_sz * sizeof (lwpdir_t));
 522                 kmem_free(old_tidhash, old_tidhash_sz * sizeof (tidhash_t));
 523         }
 524         while (ret_tidhash != NULL) {
 525                 ret_tidhash_t *next = ret_tidhash->rth_next;
 526                 kmem_free(ret_tidhash->rth_tidhash,
 527                     ret_tidhash->rth_tidhash_sz * sizeof (tidhash_t));
 528                 kmem_free(ret_tidhash, sizeof (*ret_tidhash));
 529                 ret_tidhash = next;
 530         }
 531 
 532         ASSERT(error == 0);
 533         DTRACE_PROC(exec__success);
 534         return (0);
 535 
 536 fail:
 537         DTRACE_PROC1(exec__failure, int, error);
 538 out:            /* error return */
 539         mutex_enter(&p->p_lock);
 540         curthread->t_hold = savedmask;
 541         prexecend();
 542         mutex_exit(&p->p_lock);
 543         ASSERT(error != 0);
 544         return (error);
 545 }
 546 
 547 
 548 /*
 549  * Perform generic exec duties and switchout to object-file specific
 550  * handler.
 551  */
 552 int
 553 gexec(
 554         struct vnode **vpp,
 555         struct execa *uap,
 556         struct uarg *args,
 557         struct intpdata *idatap,
 558         int level,
 559         long *execsz,
 560         caddr_t exec_file,
 561         struct cred *cred,
 562         int brand_action)
 563 {
 564         struct vnode *vp, *execvp = NULL;
 565         proc_t *pp = ttoproc(curthread);
 566         struct execsw *eswp;
 567         int error = 0;
 568         int suidflags = 0;
 569         ssize_t resid;
 570         uid_t uid, gid;
 571         struct vattr vattr;
 572         char magbuf[MAGIC_BYTES];
 573         int setid;
 574         cred_t *oldcred, *newcred = NULL;
 575         int privflags = 0;
 576         int setidfl;
 577         priv_set_t fset;
 578 
 579         /*
 580          * If the SNOCD or SUGID flag is set, turn it off and remember the
 581          * previous setting so we can restore it if we encounter an error.
 582          */
 583         if (level == 0 && (pp->p_flag & PSUIDFLAGS)) {
 584                 mutex_enter(&pp->p_lock);
 585                 suidflags = pp->p_flag & PSUIDFLAGS;
 586                 pp->p_flag &= ~PSUIDFLAGS;
 587                 mutex_exit(&pp->p_lock);
 588         }
 589 
 590         if ((error = execpermissions(*vpp, &vattr, args)) != 0)
 591                 goto bad_noclose;
 592 
 593         /* need to open vnode for stateful file systems */
 594         if ((error = VOP_OPEN(vpp, FREAD, CRED(), NULL)) != 0)
 595                 goto bad_noclose;
 596         vp = *vpp;
 597 
 598         /*
 599          * Note: to support binary compatibility with SunOS a.out
 600          * executables, we read in the first four bytes, as the
 601          * magic number is in bytes 2-3.
 602          */
 603         if (error = vn_rdwr(UIO_READ, vp, magbuf, sizeof (magbuf),
 604             (offset_t)0, UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid))
 605                 goto bad;
 606         if (resid != 0)
 607                 goto bad;
 608 
 609         if ((eswp = findexec_by_hdr(magbuf)) == NULL)
 610                 goto bad;
 611 
 612         if (level == 0 &&
 613             (privflags = execsetid(vp, &vattr, &uid, &gid, &fset,
 614             args->pfcred == NULL ? cred : args->pfcred, args->pathname)) != 0) {
 615 
 616                 /* Pfcred is a credential with a ref count of 1 */
 617 
 618                 if (args->pfcred != NULL) {
 619                         privflags |= PRIV_INCREASE|PRIV_RESET;
 620                         newcred = cred = args->pfcred;
 621                 } else {
 622                         newcred = cred = crdup(cred);
 623                 }
 624 
 625                 /* If we can, drop the PA bit */
 626                 if ((privflags & PRIV_RESET) != 0)
 627                         priv_adjust_PA(cred);
 628 
 629                 if (privflags & PRIV_SETID) {
 630                         cred->cr_uid = uid;
 631                         cred->cr_gid = gid;
 632                         cred->cr_suid = uid;
 633                         cred->cr_sgid = gid;
 634                 }
 635 
 636                 if (privflags & MAC_FLAGS) {
 637                         if (!(CR_FLAGS(cred) & NET_MAC_AWARE_INHERIT))
 638                                 CR_FLAGS(cred) &= ~NET_MAC_AWARE;
 639                         CR_FLAGS(cred) &= ~NET_MAC_AWARE_INHERIT;
 640                 }
 641 
 642                 /*
 643                  * Implement the privilege updates:
 644                  *
 645                  * Restrict with L:
 646                  *
 647                  *      I' = I & L
 648                  *
 649                  *      E' = P' = (I' + F) & A
 650                  *
 651                  * But if running under ptrace, we cap I and F with P.
 652                  */
 653                 if ((privflags & (PRIV_RESET|PRIV_FORCED)) != 0) {
 654                         if ((privflags & PRIV_INCREASE) != 0 &&
 655                             (pp->p_proc_flag & P_PR_PTRACE) != 0) {
 656                                 priv_intersect(&CR_OPPRIV(cred),
 657                                     &CR_IPRIV(cred));
 658                                 priv_intersect(&CR_OPPRIV(cred), &fset);
 659                         }
 660                         priv_intersect(&CR_LPRIV(cred), &CR_IPRIV(cred));
 661                         CR_EPRIV(cred) = CR_PPRIV(cred) = CR_IPRIV(cred);
 662                         if (privflags & PRIV_FORCED) {
 663                                 priv_set_PA(cred);
 664                                 priv_union(&fset, &CR_EPRIV(cred));
 665                                 priv_union(&fset, &CR_PPRIV(cred));
 666                         }
 667                         priv_adjust_PA(cred);
 668                 }
 669         } else if (level == 0 && args->pfcred != NULL) {
 670                 newcred = cred = args->pfcred;
 671                 privflags |= PRIV_INCREASE;
 672                 /* pfcred is not forced to adhere to these settings */
 673                 priv_intersect(&CR_LPRIV(cred), &CR_IPRIV(cred));
 674                 CR_EPRIV(cred) = CR_PPRIV(cred) = CR_IPRIV(cred);
 675                 priv_adjust_PA(cred);
 676         }
 677 
 678         /* The new image gets the inheritable secflags as its secflags */
 679         /* XXX: This probably means we have the wrong secflags when exec fails */
 680         secflag_promote(pp);
 681 
 682         /* SunOS 4.x buy-back */
 683         if ((vp->v_vfsp->vfs_flag & VFS_NOSETUID) &&
 684             (vattr.va_mode & (VSUID|VSGID))) {
 685                 char path[MAXNAMELEN];
 686                 refstr_t *mntpt = NULL;
 687                 int ret = -1;
 688 
 689                 bzero(path, sizeof (path));
 690                 zone_hold(pp->p_zone);
 691 
 692                 ret = vnodetopath(pp->p_zone->zone_rootvp, vp, path,
 693                     sizeof (path), cred);
 694 
 695                 /* fallback to mountpoint if a path can't be found */
 696                 if ((ret != 0) || (ret == 0 && path[0] == '\0'))
 697                         mntpt = vfs_getmntpoint(vp->v_vfsp);
 698 
 699                 if (mntpt == NULL)
 700                         zcmn_err(pp->p_zone->zone_id, CE_NOTE,
 701                             "!uid %d: setuid execution not allowed, "
 702                             "file=%s", cred->cr_uid, path);
 703                 else
 704                         zcmn_err(pp->p_zone->zone_id, CE_NOTE,
 705                             "!uid %d: setuid execution not allowed, "
 706                             "fs=%s, file=%s", cred->cr_uid,
 707                             ZONE_PATH_TRANSLATE(refstr_value(mntpt),
 708                             pp->p_zone), exec_file);
 709 
 710                 if (!INGLOBALZONE(pp)) {
 711                         /* zone_rootpath always has trailing / */
 712                         if (mntpt == NULL)
 713                                 cmn_err(CE_NOTE, "!zone: %s, uid: %d "
 714                                     "setuid execution not allowed, file=%s%s",
 715                                     pp->p_zone->zone_name, cred->cr_uid,
 716                                     pp->p_zone->zone_rootpath, path + 1);
 717                         else
 718                                 cmn_err(CE_NOTE, "!zone: %s, uid: %d "
 719                                     "setuid execution not allowed, fs=%s, "
 720                                     "file=%s", pp->p_zone->zone_name,
 721                                     cred->cr_uid, refstr_value(mntpt),
 722                                     exec_file);
 723                 }
 724 
 725                 if (mntpt != NULL)
 726                         refstr_rele(mntpt);
 727 
 728                 zone_rele(pp->p_zone);
 729         }
 730 
 731         /*
 732          * execsetid() told us whether or not we had to change the
 733          * credentials of the process.  In privflags, it told us
 734          * whether we gained any privileges or executed a set-uid executable.
 735          */
 736         setid = (privflags & (PRIV_SETUGID|PRIV_INCREASE|PRIV_FORCED));
 737 
 738         /*
 739          * Use /etc/system variable to determine if the stack
 740          * should be marked as executable by default.
 741          */
 742         if (noexec_user_stack)
 743                 args->stk_prot &= ~PROT_EXEC;
 744 
 745         args->execswp = eswp; /* Save execsw pointer in uarg for exec_func */
 746         args->ex_vp = vp;
 747 
 748         /*
 749          * Traditionally, the setid flags told the sub processes whether
 750          * the file just executed was set-uid or set-gid; this caused
 751          * some confusion as the 'setid' flag did not match the SUGID
 752          * process flag which is only set when the uids/gids do not match.
 753          * A script set-gid/set-uid to the real uid/gid would start with
 754          * /dev/fd/X but an executable would happily trust LD_LIBRARY_PATH.
 755          * Now we flag those cases where the calling process cannot
 756          * be trusted to influence the newly exec'ed process, either
 757          * because it runs with more privileges or when the uids/gids
 758          * do in fact not match.
 759          * This also makes the runtime linker agree with the on exec
 760          * values of SNOCD and SUGID.
 761          */
 762         setidfl = 0;
 763         if (cred->cr_uid != cred->cr_ruid || (cred->cr_rgid != cred->cr_gid &&
 764             !supgroupmember(cred->cr_gid, cred))) {
 765                 setidfl |= EXECSETID_UGIDS;
 766         }
 767         if (setid & PRIV_SETUGID)
 768                 setidfl |= EXECSETID_SETID;
 769         if (setid & PRIV_FORCED)
 770                 setidfl |= EXECSETID_PRIVS;
 771 
 772         execvp = pp->p_exec;
 773         if (execvp)
 774                 VN_HOLD(execvp);
 775 
 776         error = (*eswp->exec_func)(vp, uap, args, idatap, level, execsz,
 777             setidfl, exec_file, cred, brand_action);
 778         rw_exit(eswp->exec_lock);
 779         if (error != 0) {
 780                 if (execvp)
 781                         VN_RELE(execvp);
 782                 /*
 783                  * If this process's p_exec has been set to the vp of
 784                  * the executable by exec_func, we will return without
 785                  * calling VOP_CLOSE because proc_exit will close it
 786                  * on exit.
 787                  */
 788                 if (pp->p_exec == vp)
 789                         goto bad_noclose;
 790                 else
 791                         goto bad;
 792         }
 793 
 794         if (level == 0) {
 795                 uid_t oruid;
 796 
 797                 if (execvp != NULL) {
 798                         /*
 799                          * Close the previous executable only if we are
 800                          * at level 0.
 801                          */
 802                         (void) VOP_CLOSE(execvp, FREAD, 1, (offset_t)0,
 803                             cred, NULL);
 804                 }
 805 
 806                 mutex_enter(&pp->p_crlock);
 807 
 808                 oruid = pp->p_cred->cr_ruid;
 809 
 810                 if (newcred != NULL) {
 811                         /*
 812                          * Free the old credentials, and set the new ones.
 813                          * Do this for both the process and the (single) thread.
 814                          */
 815                         crfree(pp->p_cred);
 816                         pp->p_cred = cred;   /* cred already held for proc */
 817                         crhold(cred);           /* hold new cred for thread */
 818                         /*
 819                          * DTrace accesses t_cred in probe context.  t_cred
 820                          * must always be either NULL, or point to a valid,
 821                          * allocated cred structure.
 822                          */
 823                         oldcred = curthread->t_cred;
 824                         curthread->t_cred = cred;
 825                         crfree(oldcred);
 826 
 827                         if (priv_basic_test >= 0 &&
 828                             !PRIV_ISASSERT(&CR_IPRIV(newcred),
 829                             priv_basic_test)) {
 830                                 pid_t pid = pp->p_pid;
 831                                 char *fn = PTOU(pp)->u_comm;
 832 
 833                                 cmn_err(CE_WARN, "%s[%d]: exec: basic_test "
 834                                     "privilege removed from E/I", fn, pid);
 835                         }
 836                 }
 837                 /*
 838                  * On emerging from a successful exec(), the saved
 839                  * uid and gid equal the effective uid and gid.
 840                  */
 841                 cred->cr_suid = cred->cr_uid;
 842                 cred->cr_sgid = cred->cr_gid;
 843 
 844                 /*
 845                  * If the real and effective ids do not match, this
 846                  * is a setuid process that should not dump core.
 847                  * The group comparison is tricky; we prevent the code
 848                  * from flagging SNOCD when executing with an effective gid
 849                  * which is a supplementary group.
 850                  */
 851                 if (cred->cr_ruid != cred->cr_uid ||
 852                     (cred->cr_rgid != cred->cr_gid &&
 853                     !supgroupmember(cred->cr_gid, cred)) ||
 854                     (privflags & PRIV_INCREASE) != 0)
 855                         suidflags = PSUIDFLAGS;
 856                 else
 857                         suidflags = 0;
 858 
 859                 mutex_exit(&pp->p_crlock);
 860                 if (newcred != NULL && oruid != newcred->cr_ruid) {
 861                         /* Note that the process remains in the same zone. */
 862                         mutex_enter(&pidlock);
 863                         upcount_dec(oruid, crgetzoneid(newcred));
 864                         upcount_inc(newcred->cr_ruid, crgetzoneid(newcred));
 865                         mutex_exit(&pidlock);
 866                 }
 867                 if (suidflags) {
 868                         mutex_enter(&pp->p_lock);
 869                         pp->p_flag |= suidflags;
 870                         mutex_exit(&pp->p_lock);
 871                 }
 872                 if (setid && (pp->p_proc_flag & P_PR_PTRACE) == 0) {
 873                         /*
 874                          * If process is traced via /proc, arrange to
 875                          * invalidate the associated /proc vnode.
 876                          */
 877                         if (pp->p_plist || (pp->p_proc_flag & P_PR_TRACE))
 878                                 args->traceinval = 1;
 879                 }
 880                 if (pp->p_proc_flag & P_PR_PTRACE)
 881                         psignal(pp, SIGTRAP);
 882                 if (args->traceinval)
 883                         prinvalidate(&pp->p_user);
 884         }
 885         if (execvp)
 886                 VN_RELE(execvp);
 887         return (0);
 888 
 889 bad:
 890         (void) VOP_CLOSE(vp, FREAD, 1, (offset_t)0, cred, NULL);
 891 
 892 bad_noclose:
 893         if (newcred != NULL)
 894                 crfree(newcred);
 895         if (error == 0)
 896                 error = ENOEXEC;
 897 
 898         if (suidflags) {
 899                 mutex_enter(&pp->p_lock);
 900                 pp->p_flag |= suidflags;
 901                 mutex_exit(&pp->p_lock);
 902         }
 903         return (error);
 904 }
 905 
 906 extern char *execswnames[];
 907 
 908 struct execsw *
 909 allocate_execsw(char *name, char *magic, size_t magic_size)
 910 {
 911         int i, j;
 912         char *ename;
 913         char *magicp;
 914 
 915         mutex_enter(&execsw_lock);
 916         for (i = 0; i < nexectype; i++) {
 917                 if (execswnames[i] == NULL) {
 918                         ename = kmem_alloc(strlen(name) + 1, KM_SLEEP);
 919                         (void) strcpy(ename, name);
 920                         execswnames[i] = ename;
 921                         /*
 922                          * Set the magic number last so that we
 923                          * don't need to hold the execsw_lock in
 924                          * findexectype().
 925                          */
 926                         magicp = kmem_alloc(magic_size, KM_SLEEP);
 927                         for (j = 0; j < magic_size; j++)
 928                                 magicp[j] = magic[j];
 929                         execsw[i].exec_magic = magicp;
 930                         mutex_exit(&execsw_lock);
 931                         return (&execsw[i]);
 932                 }
 933         }
 934         mutex_exit(&execsw_lock);
 935         return (NULL);
 936 }
 937 
 938 /*
 939  * Find the exec switch table entry with the corresponding magic string.
 940  */
 941 struct execsw *
 942 findexecsw(char *magic)
 943 {
 944         struct execsw *eswp;
 945 
 946         for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) {
 947                 ASSERT(eswp->exec_maglen <= MAGIC_BYTES);
 948                 if (magic && eswp->exec_maglen != 0 &&
 949                     bcmp(magic, eswp->exec_magic, eswp->exec_maglen) == 0)
 950                         return (eswp);
 951         }
 952         return (NULL);
 953 }
 954 
 955 /*
 956  * Find the execsw[] index for the given exec header string by looking for the
 957  * magic string at a specified offset and length for each kind of executable
 958  * file format until one matches.  If no execsw[] entry is found, try to
 959  * autoload a module for this magic string.
 960  */
 961 struct execsw *
 962 findexec_by_hdr(char *header)
 963 {
 964         struct execsw *eswp;
 965 
 966         for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) {
 967                 ASSERT(eswp->exec_maglen <= MAGIC_BYTES);
 968                 if (header && eswp->exec_maglen != 0 &&
 969                     bcmp(&header[eswp->exec_magoff], eswp->exec_magic,
 970                     eswp->exec_maglen) == 0) {
 971                         if (hold_execsw(eswp) != 0)
 972                                 return (NULL);
 973                         return (eswp);
 974                 }
 975         }
 976         return (NULL);  /* couldn't find the type */
 977 }
 978 
 979 /*
 980  * Find the execsw[] index for the given magic string.  If no execsw[] entry
 981  * is found, try to autoload a module for this magic string.
 982  */
 983 struct execsw *
 984 findexec_by_magic(char *magic)
 985 {
 986         struct execsw *eswp;
 987 
 988         for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) {
 989                 ASSERT(eswp->exec_maglen <= MAGIC_BYTES);
 990                 if (magic && eswp->exec_maglen != 0 &&
 991                     bcmp(magic, eswp->exec_magic, eswp->exec_maglen) == 0) {
 992                         if (hold_execsw(eswp) != 0)
 993                                 return (NULL);
 994                         return (eswp);
 995                 }
 996         }
 997         return (NULL);  /* couldn't find the type */
 998 }
 999 
1000 static int
1001 hold_execsw(struct execsw *eswp)
1002 {
1003         char *name;
1004 
1005         rw_enter(eswp->exec_lock, RW_READER);
1006         while (!LOADED_EXEC(eswp)) {
1007                 rw_exit(eswp->exec_lock);
1008                 name = execswnames[eswp-execsw];
1009                 ASSERT(name);
1010                 if (modload("exec", name) == -1)
1011                         return (-1);
1012                 rw_enter(eswp->exec_lock, RW_READER);
1013         }
1014         return (0);
1015 }
1016 
1017 static int
1018 execsetid(struct vnode *vp, struct vattr *vattrp, uid_t *uidp, uid_t *gidp,
1019     priv_set_t *fset, cred_t *cr, const char *pathname)
1020 {
1021         proc_t *pp = ttoproc(curthread);
1022         uid_t uid, gid;
1023         int privflags = 0;
1024 
1025         /*
1026          * Remember credentials.
1027          */
1028         uid = cr->cr_uid;
1029         gid = cr->cr_gid;
1030 
1031         /* Will try to reset the PRIV_AWARE bit later. */
1032         if ((CR_FLAGS(cr) & (PRIV_AWARE|PRIV_AWARE_INHERIT)) == PRIV_AWARE)
1033                 privflags |= PRIV_RESET;
1034 
1035         if ((vp->v_vfsp->vfs_flag & VFS_NOSETUID) == 0) {
1036                 /*
1037                  * If it's a set-uid root program we perform the
1038                  * forced privilege look-aside. This has three possible
1039                  * outcomes:
1040                  *      no look aside information -> treat as before
1041                  *      look aside in Limit set -> apply forced privs
1042                  *      look aside not in Limit set -> ignore set-uid root
1043                  *
1044                  * Ordinary set-uid root execution only allowed if the limit
1045                  * set holds all unsafe privileges.
1046                  */
1047                 if (vattrp->va_mode & VSUID) {
1048                         if (vattrp->va_uid == 0) {
1049                                 int res = get_forced_privs(cr, pathname, fset);
1050 
1051                                 switch (res) {
1052                                 case -1:
1053                                         if (priv_issubset(&priv_unsafe,
1054                                             &CR_LPRIV(cr))) {
1055                                                 uid = vattrp->va_uid;
1056                                                 privflags |= PRIV_SETUGID;
1057                                         }
1058                                         break;
1059                                 case 0:
1060                                         privflags |= PRIV_FORCED|PRIV_INCREASE;
1061                                         break;
1062                                 default:
1063                                         break;
1064                                 }
1065                         } else {
1066                                 uid = vattrp->va_uid;
1067                                 privflags |= PRIV_SETUGID;
1068                         }
1069                 }
1070                 if (vattrp->va_mode & VSGID) {
1071                         gid = vattrp->va_gid;
1072                         privflags |= PRIV_SETUGID;
1073                 }
1074         }
1075 
1076         /*
1077          * Do we need to change our credential anyway?
1078          * This is the case when E != I or P != I, as
1079          * we need to do the assignments (with F empty and A full)
1080          * Or when I is not a subset of L; in that case we need to
1081          * enforce L.
1082          *
1083          *              I' = L & I
1084          *
1085          *              E' = P' = (I' + F) & A
1086          * or
1087          *              E' = P' = I'
1088          */
1089         if (!priv_isequalset(&CR_EPRIV(cr), &CR_IPRIV(cr)) ||
1090             !priv_issubset(&CR_IPRIV(cr), &CR_LPRIV(cr)) ||
1091             !priv_isequalset(&CR_PPRIV(cr), &CR_IPRIV(cr)))
1092                 privflags |= PRIV_RESET;
1093 
1094         /* Child has more privileges than parent */
1095         if (!priv_issubset(&CR_IPRIV(cr), &CR_PPRIV(cr)))
1096                 privflags |= PRIV_INCREASE;
1097 
1098         /* If MAC-aware flag(s) are on, need to update cred to remove. */
1099         if ((CR_FLAGS(cr) & NET_MAC_AWARE) ||
1100             (CR_FLAGS(cr) & NET_MAC_AWARE_INHERIT))
1101                 privflags |= MAC_FLAGS;
1102         /*
1103          * Set setuid/setgid protections if no ptrace() compatibility.
1104          * For privileged processes, honor setuid/setgid even in
1105          * the presence of ptrace() compatibility.
1106          */
1107         if (((pp->p_proc_flag & P_PR_PTRACE) == 0 ||
1108             PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, (uid == 0))) &&
1109             (cr->cr_uid != uid ||
1110             cr->cr_gid != gid ||
1111             cr->cr_suid != uid ||
1112             cr->cr_sgid != gid)) {
1113                 *uidp = uid;
1114                 *gidp = gid;
1115                 privflags |= PRIV_SETID;
1116         }
1117         return (privflags);
1118 }
1119 
1120 int
1121 execpermissions(struct vnode *vp, struct vattr *vattrp, struct uarg *args)
1122 {
1123         int error;
1124         proc_t *p = ttoproc(curthread);
1125 
1126         vattrp->va_mask = AT_MODE | AT_UID | AT_GID | AT_SIZE;
1127         if (error = VOP_GETATTR(vp, vattrp, ATTR_EXEC, p->p_cred, NULL))
1128                 return (error);
1129         /*
1130          * Check the access mode.
1131          * If VPROC, ask /proc if the file is an object file.
1132          */
1133         if ((error = VOP_ACCESS(vp, VEXEC, 0, p->p_cred, NULL)) != 0 ||
1134             !(vp->v_type == VREG || (vp->v_type == VPROC && pr_isobject(vp))) ||
1135             (vp->v_vfsp->vfs_flag & VFS_NOEXEC) != 0 ||
1136             (vattrp->va_mode & (VEXEC|(VEXEC>>3)|(VEXEC>>6))) == 0) {
1137                 if (error == 0)
1138                         error = EACCES;
1139                 return (error);
1140         }
1141 
1142         if ((p->p_plist || (p->p_proc_flag & (P_PR_PTRACE|P_PR_TRACE))) &&
1143             (error = VOP_ACCESS(vp, VREAD, 0, p->p_cred, NULL))) {
1144                 /*
1145                  * If process is under ptrace(2) compatibility,
1146                  * fail the exec(2).
1147                  */
1148                 if (p->p_proc_flag & P_PR_PTRACE)
1149                         goto bad;
1150                 /*
1151                  * Process is traced via /proc.
1152                  * Arrange to invalidate the /proc vnode.
1153                  */
1154                 args->traceinval = 1;
1155         }
1156         return (0);
1157 bad:
1158         if (error == 0)
1159                 error = ENOEXEC;
1160         return (error);
1161 }
1162 
1163 /*
1164  * Map a section of an executable file into the user's
1165  * address space.
1166  */
1167 int
1168 execmap(struct vnode *vp, caddr_t addr, size_t len, size_t zfodlen,
1169     off_t offset, int prot, int page, uint_t szc)
1170 {
1171         int error = 0;
1172         off_t oldoffset;
1173         caddr_t zfodbase, oldaddr;
1174         size_t end, oldlen;
1175         size_t zfoddiff;
1176         label_t ljb;
1177         proc_t *p = ttoproc(curthread);
1178 
1179         oldaddr = addr;
1180         addr = (caddr_t)((uintptr_t)addr & (uintptr_t)PAGEMASK);
1181         if (len) {
1182                 oldlen = len;
1183                 len += ((size_t)oldaddr - (size_t)addr);
1184                 oldoffset = offset;
1185                 offset = (off_t)((uintptr_t)offset & PAGEMASK);
1186                 if (page) {
1187                         spgcnt_t  prefltmem, availm, npages;
1188                         int preread;
1189                         uint_t mflag = MAP_PRIVATE | MAP_FIXED;
1190 
1191                         if ((prot & (PROT_WRITE | PROT_EXEC)) == PROT_EXEC) {
1192                                 mflag |= MAP_TEXT;
1193                         } else {
1194                                 mflag |= MAP_INITDATA;
1195                         }
1196 
1197                         if (valid_usr_range(addr, len, prot, p->p_as,
1198                             p->p_as->a_userlimit) != RANGE_OKAY) {
1199                                 error = ENOMEM;
1200                                 goto bad;
1201                         }
1202                         if (error = VOP_MAP(vp, (offset_t)offset,
1203                             p->p_as, &addr, len, prot, PROT_ALL,
1204                             mflag, CRED(), NULL))
1205                                 goto bad;
1206 
1207                         /*
1208                          * If the segment can fit, then we prefault
1209                          * the entire segment in.  This is based on the
1210                          * model that says the best working set of a
1211                          * small program is all of its pages.
1212                          */
1213                         npages = (spgcnt_t)btopr(len);
1214                         prefltmem = freemem - desfree;
1215                         preread =
1216                             (npages < prefltmem && len < PGTHRESH) ? 1 : 0;
1217 
1218                         /*
1219                          * If we aren't prefaulting the segment,
1220                          * increment "deficit", if necessary to ensure
1221                          * that pages will become available when this
1222                          * process starts executing.
1223                          */
1224                         availm = freemem - lotsfree;
1225                         if (preread == 0 && npages > availm &&
1226                             deficit < lotsfree) {
1227                                 deficit += MIN((pgcnt_t)(npages - availm),
1228                                     lotsfree - deficit);
1229                         }
1230 
1231                         if (preread) {
1232                                 TRACE_2(TR_FAC_PROC, TR_EXECMAP_PREREAD,
1233                                     "execmap preread:freemem %d size %lu",
1234                                     freemem, len);
1235                                 (void) as_fault(p->p_as->a_hat, p->p_as,
1236                                     (caddr_t)addr, len, F_INVAL, S_READ);
1237                         }
1238                 } else {
1239                         if (valid_usr_range(addr, len, prot, p->p_as,
1240                             p->p_as->a_userlimit) != RANGE_OKAY) {
1241                                 error = ENOMEM;
1242                                 goto bad;
1243                         }
1244 
1245                         if (error = as_map(p->p_as, addr, len,
1246                             segvn_create, zfod_argsp))
1247                                 goto bad;
1248                         /*
1249                          * Read in the segment in one big chunk.
1250                          */
1251                         if (error = vn_rdwr(UIO_READ, vp, (caddr_t)oldaddr,
1252                             oldlen, (offset_t)oldoffset, UIO_USERSPACE, 0,
1253                             (rlim64_t)0, CRED(), (ssize_t *)0))
1254                                 goto bad;
1255                         /*
1256                          * Now set protections.
1257                          */
1258                         if (prot != PROT_ZFOD) {
1259                                 (void) as_setprot(p->p_as, (caddr_t)addr,
1260                                     len, prot);
1261                         }
1262                 }
1263         }
1264 
1265         if (zfodlen) {
1266                 struct as *as = curproc->p_as;
1267                 struct seg *seg;
1268                 uint_t zprot = 0;
1269 
1270                 end = (size_t)addr + len;
1271                 zfodbase = (caddr_t)roundup(end, PAGESIZE);
1272                 zfoddiff = (uintptr_t)zfodbase - end;
1273                 if (zfoddiff) {
1274                         /*
1275                          * Before we go to zero the remaining space on the last
1276                          * page, make sure we have write permission.
1277                          *
1278                          * Normal illumos binaries don't even hit the case
1279                          * where we have to change permission on the last page
1280                          * since their protection is typically either
1281                          *    PROT_USER | PROT_WRITE | PROT_READ
1282                          * or
1283                          *    PROT_ZFOD (same as PROT_ALL).
1284                          *
1285                          * We need to be careful how we zero-fill the last page
1286                          * if the segment protection does not include
1287                          * PROT_WRITE. Using as_setprot() can cause the VM
1288                          * segment code to call segvn_vpage(), which must
1289                          * allocate a page struct for each page in the segment.
1290                          * If we have a very large segment, this may fail, so
1291                          * we have to check for that, even though we ignore
1292                          * other return values from as_setprot.
1293                          */
1294 
1295                         AS_LOCK_ENTER(as, &as->a_lock, RW_READER);
1296                         seg = as_segat(curproc->p_as, (caddr_t)end);
1297                         if (seg != NULL)
1298                                 SEGOP_GETPROT(seg, (caddr_t)end, zfoddiff - 1,
1299                                     &zprot);
1300                         AS_LOCK_EXIT(as, &as->a_lock);
1301 
1302                         if (seg != NULL && (zprot & PROT_WRITE) == 0) {
1303                                 if (as_setprot(as, (caddr_t)end, zfoddiff - 1,
1304                                     zprot | PROT_WRITE) == ENOMEM) {
1305                                         error = ENOMEM;
1306                                         goto bad;
1307                                 }
1308                         }
1309 
1310                         if (on_fault(&ljb)) {
1311                                 no_fault();
1312                                 if (seg != NULL && (zprot & PROT_WRITE) == 0)
1313                                         (void) as_setprot(as, (caddr_t)end,
1314                                             zfoddiff - 1, zprot);
1315                                 error = EFAULT;
1316                                 goto bad;
1317                         }
1318                         uzero((void *)end, zfoddiff);
1319                         no_fault();
1320                         if (seg != NULL && (zprot & PROT_WRITE) == 0)
1321                                 (void) as_setprot(as, (caddr_t)end,
1322                                     zfoddiff - 1, zprot);
1323                 }
1324                 if (zfodlen > zfoddiff) {
1325                         struct segvn_crargs crargs =
1326                             SEGVN_ZFOD_ARGS(PROT_ZFOD, PROT_ALL);
1327 
1328                         zfodlen -= zfoddiff;
1329                         if (valid_usr_range(zfodbase, zfodlen, prot, p->p_as,
1330                             p->p_as->a_userlimit) != RANGE_OKAY) {
1331                                 error = ENOMEM;
1332                                 goto bad;
1333                         }
1334                         if (szc > 0) {
1335                                 /*
1336                                  * ASSERT alignment because the mapelfexec()
1337                                  * caller for the szc > 0 case extended zfod
1338                                  * so it's end is pgsz aligned.
1339                                  */
1340                                 size_t pgsz = page_get_pagesize(szc);
1341                                 ASSERT(IS_P2ALIGNED(zfodbase + zfodlen, pgsz));
1342 
1343                                 if (IS_P2ALIGNED(zfodbase, pgsz)) {
1344                                         crargs.szc = szc;
1345                                 } else {
1346                                         crargs.szc = AS_MAP_HEAP;
1347                                 }
1348                         } else {
1349                                 crargs.szc = AS_MAP_NO_LPOOB;
1350                         }
1351                         if (error = as_map(p->p_as, (caddr_t)zfodbase,
1352                             zfodlen, segvn_create, &crargs))
1353                                 goto bad;
1354                         if (prot != PROT_ZFOD) {
1355                                 (void) as_setprot(p->p_as, (caddr_t)zfodbase,
1356                                     zfodlen, prot);
1357                         }
1358                 }
1359         }
1360         return (0);
1361 bad:
1362         return (error);
1363 }
1364 
1365 void
1366 setexecenv(struct execenv *ep)
1367 {
1368         proc_t *p = ttoproc(curthread);
1369         klwp_t *lwp = ttolwp(curthread);
1370         struct vnode *vp;
1371 
1372         p->p_bssbase = ep->ex_bssbase;
1373         p->p_brkbase = ep->ex_brkbase;
1374         p->p_brksize = ep->ex_brksize;
1375         if (p->p_exec)
1376                 VN_RELE(p->p_exec);  /* out with the old */
1377         vp = p->p_exec = ep->ex_vp;
1378         if (vp != NULL)
1379                 VN_HOLD(vp);            /* in with the new */
1380 
1381         lwp->lwp_sigaltstack.ss_sp = 0;
1382         lwp->lwp_sigaltstack.ss_size = 0;
1383         lwp->lwp_sigaltstack.ss_flags = SS_DISABLE;
1384 }
1385 
1386 int
1387 execopen(struct vnode **vpp, int *fdp)
1388 {
1389         struct vnode *vp = *vpp;
1390         file_t *fp;
1391         int error = 0;
1392         int filemode = FREAD;
1393 
1394         VN_HOLD(vp);            /* open reference */
1395         if (error = falloc(NULL, filemode, &fp, fdp)) {
1396                 VN_RELE(vp);
1397                 *fdp = -1;      /* just in case falloc changed value */
1398                 return (error);
1399         }
1400         if (error = VOP_OPEN(&vp, filemode, CRED(), NULL)) {
1401                 VN_RELE(vp);
1402                 setf(*fdp, NULL);
1403                 unfalloc(fp);
1404                 *fdp = -1;
1405                 return (error);
1406         }
1407         *vpp = vp;              /* vnode should not have changed */
1408         fp->f_vnode = vp;
1409         mutex_exit(&fp->f_tlock);
1410         setf(*fdp, fp);
1411         return (0);
1412 }
1413 
1414 int
1415 execclose(int fd)
1416 {
1417         return (closeandsetf(fd, NULL));
1418 }
1419 
1420 
1421 /*
1422  * noexec stub function.
1423  */
1424 /*ARGSUSED*/
1425 int
1426 noexec(
1427     struct vnode *vp,
1428     struct execa *uap,
1429     struct uarg *args,
1430     struct intpdata *idatap,
1431     int level,
1432     long *execsz,
1433     int setid,
1434     caddr_t exec_file,
1435     struct cred *cred)
1436 {
1437         cmn_err(CE_WARN, "missing exec capability for %s", uap->fname);
1438         return (ENOEXEC);
1439 }
1440 
1441 /*
1442  * Support routines for building a user stack.
1443  *
1444  * execve(path, argv, envp) must construct a new stack with the specified
1445  * arguments and environment variables (see exec_args() for a description
1446  * of the user stack layout).  To do this, we copy the arguments and
1447  * environment variables from the old user address space into the kernel,
1448  * free the old as, create the new as, and copy our buffered information
1449  * to the new stack.  Our kernel buffer has the following structure:
1450  *
1451  *      +-----------------------+ <--- stk_base + stk_size
1452  *      | string offsets        |
1453  *      +-----------------------+ <--- stk_offp
1454  *      |                       |
1455  *      | STK_AVAIL() space     |
1456  *      |                       |
1457  *      +-----------------------+ <--- stk_strp
1458  *      | strings               |
1459  *      +-----------------------+ <--- stk_base
1460  *
1461  * When we add a string, we store the string's contents (including the null
1462  * terminator) at stk_strp, and we store the offset of the string relative to
1463  * stk_base at --stk_offp.  At strings are added, stk_strp increases and
1464  * stk_offp decreases.  The amount of space remaining, STK_AVAIL(), is just
1465  * the difference between these pointers.  If we run out of space, we return
1466  * an error and exec_args() starts all over again with a buffer twice as large.
1467  * When we're all done, the kernel buffer looks like this:
1468  *
1469  *      +-----------------------+ <--- stk_base + stk_size
1470  *      | argv[0] offset        |
1471  *      +-----------------------+
1472  *      | ...                   |
1473  *      +-----------------------+
1474  *      | argv[argc-1] offset   |
1475  *      +-----------------------+
1476  *      | envp[0] offset        |
1477  *      +-----------------------+
1478  *      | ...                   |
1479  *      +-----------------------+
1480  *      | envp[envc-1] offset   |
1481  *      +-----------------------+
1482  *      | AT_SUN_PLATFORM offset|
1483  *      +-----------------------+
1484  *      | AT_SUN_EXECNAME offset|
1485  *      +-----------------------+ <--- stk_offp
1486  *      |                       |
1487  *      | STK_AVAIL() space     |
1488  *      |                       |
1489  *      +-----------------------+ <--- stk_strp
1490  *      | AT_SUN_EXECNAME offset|
1491  *      +-----------------------+
1492  *      | AT_SUN_PLATFORM offset|
1493  *      +-----------------------+
1494  *      | envp[envc-1] string   |
1495  *      +-----------------------+
1496  *      | ...                   |
1497  *      +-----------------------+
1498  *      | envp[0] string        |
1499  *      +-----------------------+
1500  *      | argv[argc-1] string   |
1501  *      +-----------------------+
1502  *      | ...                   |
1503  *      +-----------------------+
1504  *      | argv[0] string        |
1505  *      +-----------------------+ <--- stk_base
1506  */
1507 
1508 #define STK_AVAIL(args)         ((char *)(args)->stk_offp - (args)->stk_strp)
1509 
1510 /*
1511  * Add a string to the stack.
1512  */
1513 static int
1514 stk_add(uarg_t *args, const char *sp, enum uio_seg segflg)
1515 {
1516         int error;
1517         size_t len;
1518 
1519         if (STK_AVAIL(args) < sizeof (int))
1520                 return (E2BIG);
1521         *--args->stk_offp = args->stk_strp - args->stk_base;
1522 
1523         if (segflg == UIO_USERSPACE) {
1524                 error = copyinstr(sp, args->stk_strp, STK_AVAIL(args), &len);
1525                 if (error != 0)
1526                         return (error);
1527         } else {
1528                 len = strlen(sp) + 1;
1529                 if (len > STK_AVAIL(args))
1530                         return (E2BIG);
1531                 bcopy(sp, args->stk_strp, len);
1532         }
1533 
1534         args->stk_strp += len;
1535 
1536         return (0);
1537 }
1538 
1539 static int
1540 stk_getptr(uarg_t *args, char *src, char **dst)
1541 {
1542         int error;
1543 
1544         if (args->from_model == DATAMODEL_NATIVE) {
1545                 ulong_t ptr;
1546                 error = fulword(src, &ptr);
1547                 *dst = (caddr_t)ptr;
1548         } else {
1549                 uint32_t ptr;
1550                 error = fuword32(src, &ptr);
1551                 *dst = (caddr_t)(uintptr_t)ptr;
1552         }
1553         return (error);
1554 }
1555 
1556 static int
1557 stk_putptr(uarg_t *args, char *addr, char *value)
1558 {
1559         if (args->to_model == DATAMODEL_NATIVE)
1560                 return (sulword(addr, (ulong_t)value));
1561         else
1562                 return (suword32(addr, (uint32_t)(uintptr_t)value));
1563 }
1564 
1565 static int
1566 stk_copyin(execa_t *uap, uarg_t *args, intpdata_t *intp, void **auxvpp)
1567 {
1568         char *sp;
1569         int argc, error;
1570         int argv_empty = 0;
1571         size_t ptrsize = args->from_ptrsize;
1572         size_t size, pad;
1573         char *argv = (char *)uap->argp;
1574         char *envp = (char *)uap->envp;
1575 
1576         /*
1577          * Copy interpreter's name and argument to argv[0] and argv[1].
1578          */
1579         if (intp != NULL && intp->intp_name != NULL) {
1580                 if ((error = stk_add(args, intp->intp_name, UIO_SYSSPACE)) != 0)
1581                         return (error);
1582                 if (intp->intp_arg != NULL &&
1583                     (error = stk_add(args, intp->intp_arg, UIO_SYSSPACE)) != 0)
1584                         return (error);
1585                 if (args->fname != NULL)
1586                         error = stk_add(args, args->fname, UIO_SYSSPACE);
1587                 else
1588                         error = stk_add(args, uap->fname, UIO_USERSPACE);
1589                 if (error)
1590                         return (error);
1591 
1592                 /*
1593                  * Check for an empty argv[].
1594                  */
1595                 if (stk_getptr(args, argv, &sp))
1596                         return (EFAULT);
1597                 if (sp == NULL)
1598                         argv_empty = 1;
1599 
1600                 argv += ptrsize;                /* ignore original argv[0] */
1601         }
1602 
1603         if (argv_empty == 0) {
1604                 /*
1605                  * Add argv[] strings to the stack.
1606                  */
1607                 for (;;) {
1608                         if (stk_getptr(args, argv, &sp))
1609                                 return (EFAULT);
1610                         if (sp == NULL)
1611                                 break;
1612                         if ((error = stk_add(args, sp, UIO_USERSPACE)) != 0)
1613                                 return (error);
1614                         argv += ptrsize;
1615                 }
1616         }
1617         argc = (int *)(args->stk_base + args->stk_size) - args->stk_offp;
1618         args->arglen = args->stk_strp - args->stk_base;
1619 
1620         /*
1621          * Add environ[] strings to the stack.
1622          */
1623         if (envp != NULL) {
1624                 for (;;) {
1625                         char *tmp = args->stk_strp;
1626                         if (stk_getptr(args, envp, &sp))
1627                                 return (EFAULT);
1628                         if (sp == NULL)
1629                                 break;
1630                         if ((error = stk_add(args, sp, UIO_USERSPACE)) != 0)
1631                                 return (error);
1632                         if (args->scrubenv && strncmp(tmp, "LD_", 3) == 0) {
1633                                 /* Undo the copied string */
1634                                 args->stk_strp = tmp;
1635                                 *(args->stk_offp++) = NULL;
1636                         }
1637                         envp += ptrsize;
1638                 }
1639         }
1640         args->na = (int *)(args->stk_base + args->stk_size) - args->stk_offp;
1641         args->ne = args->na - argc;
1642 
1643         /*
1644          * Add AT_SUN_PLATFORM, AT_SUN_EXECNAME, AT_SUN_BRANDNAME, and
1645          * AT_SUN_EMULATOR strings to the stack.
1646          */
1647         if (auxvpp != NULL && *auxvpp != NULL) {
1648                 if ((error = stk_add(args, platform, UIO_SYSSPACE)) != 0)
1649                         return (error);
1650                 if ((error = stk_add(args, args->pathname, UIO_SYSSPACE)) != 0)
1651                         return (error);
1652                 if (args->brandname != NULL &&
1653                     (error = stk_add(args, args->brandname, UIO_SYSSPACE)) != 0)
1654                         return (error);
1655                 if (args->emulator != NULL &&
1656                     (error = stk_add(args, args->emulator, UIO_SYSSPACE)) != 0)
1657                         return (error);
1658         }
1659 
1660         /*
1661          * Compute the size of the stack.  This includes all the pointers,
1662          * the space reserved for the aux vector, and all the strings.
1663          * The total number of pointers is args->na (which is argc + envc)
1664          * plus 4 more: (1) a pointer's worth of space for argc; (2) the NULL
1665          * after the last argument (i.e. argv[argc]); (3) the NULL after the
1666          * last environment variable (i.e. envp[envc]); and (4) the NULL after
1667          * all the strings, at the very top of the stack.
1668          */
1669         size = (args->na + 4) * args->to_ptrsize + args->auxsize +
1670             (args->stk_strp - args->stk_base);
1671 
1672         /*
1673          * Pad the string section with zeroes to align the stack size.
1674          */
1675         pad = P2NPHASE(size, args->stk_align);
1676 
1677         if (STK_AVAIL(args) < pad)
1678                 return (E2BIG);
1679 
1680         args->usrstack_size = size + pad;
1681 
1682         while (pad-- != 0)
1683                 *args->stk_strp++ = 0;
1684 
1685         args->nc = args->stk_strp - args->stk_base;
1686 
1687         return (0);
1688 }
1689 
1690 static int
1691 stk_copyout(uarg_t *args, char *usrstack, void **auxvpp, user_t *up)
1692 {
1693         size_t ptrsize = args->to_ptrsize;
1694         ssize_t pslen;
1695         char *kstrp = args->stk_base;
1696         char *ustrp = usrstack - args->nc - ptrsize;
1697         char *usp = usrstack - args->usrstack_size;
1698         int *offp = (int *)(args->stk_base + args->stk_size);
1699         int envc = args->ne;
1700         int argc = args->na - envc;
1701         int i;
1702 
1703         /*
1704          * Record argc for /proc.
1705          */
1706         up->u_argc = argc;
1707 
1708         /*
1709          * Put argc on the stack.  Note that even though it's an int,
1710          * it always consumes ptrsize bytes (for alignment).
1711          */
1712         if (stk_putptr(args, usp, (char *)(uintptr_t)argc))
1713                 return (-1);
1714 
1715         /*
1716          * Add argc space (ptrsize) to usp and record argv for /proc.
1717          */
1718         up->u_argv = (uintptr_t)(usp += ptrsize);
1719 
1720         /*
1721          * Put the argv[] pointers on the stack.
1722          */
1723         for (i = 0; i < argc; i++, usp += ptrsize)
1724                 if (stk_putptr(args, usp, &ustrp[*--offp]))
1725                         return (-1);
1726 
1727         /*
1728          * Copy arguments to u_psargs.
1729          */
1730         pslen = MIN(args->arglen, PSARGSZ) - 1;
1731         for (i = 0; i < pslen; i++)
1732                 up->u_psargs[i] = (kstrp[i] == '\0' ? ' ' : kstrp[i]);
1733         while (i < PSARGSZ)
1734                 up->u_psargs[i++] = '\0';
1735 
1736         /*
1737          * Add space for argv[]'s NULL terminator (ptrsize) to usp and
1738          * record envp for /proc.
1739          */
1740         up->u_envp = (uintptr_t)(usp += ptrsize);
1741 
1742         /*
1743          * Put the envp[] pointers on the stack.
1744          */
1745         for (i = 0; i < envc; i++, usp += ptrsize)
1746                 if (stk_putptr(args, usp, &ustrp[*--offp]))
1747                         return (-1);
1748 
1749         /*
1750          * Add space for envp[]'s NULL terminator (ptrsize) to usp and
1751          * remember where the stack ends, which is also where auxv begins.
1752          */
1753         args->stackend = usp += ptrsize;
1754 
1755         /*
1756          * Put all the argv[], envp[], and auxv strings on the stack.
1757          */
1758         if (copyout(args->stk_base, ustrp, args->nc))
1759                 return (-1);
1760 
1761         /*
1762          * Fill in the aux vector now that we know the user stack addresses
1763          * for the AT_SUN_PLATFORM, AT_SUN_EXECNAME, AT_SUN_BRANDNAME and
1764          * AT_SUN_EMULATOR strings.
1765          */
1766         if (auxvpp != NULL && *auxvpp != NULL) {
1767                 if (args->to_model == DATAMODEL_NATIVE) {
1768                         auxv_t **a = (auxv_t **)auxvpp;
1769                         ADDAUX(*a, AT_SUN_PLATFORM, (long)&ustrp[*--offp])
1770                         ADDAUX(*a, AT_SUN_EXECNAME, (long)&ustrp[*--offp])
1771                         if (args->brandname != NULL)
1772                                 ADDAUX(*a,
1773                                     AT_SUN_BRANDNAME, (long)&ustrp[*--offp])
1774                         if (args->emulator != NULL)
1775                                 ADDAUX(*a,
1776                                     AT_SUN_EMULATOR, (long)&ustrp[*--offp])
1777                 } else {
1778                         auxv32_t **a = (auxv32_t **)auxvpp;
1779                         ADDAUX(*a,
1780                             AT_SUN_PLATFORM, (int)(uintptr_t)&ustrp[*--offp])
1781                         ADDAUX(*a,
1782                             AT_SUN_EXECNAME, (int)(uintptr_t)&ustrp[*--offp])
1783                         if (args->brandname != NULL)
1784                                 ADDAUX(*a, AT_SUN_BRANDNAME,
1785                                     (int)(uintptr_t)&ustrp[*--offp])
1786                         if (args->emulator != NULL)
1787                                 ADDAUX(*a, AT_SUN_EMULATOR,
1788                                     (int)(uintptr_t)&ustrp[*--offp])
1789                 }
1790         }
1791 
1792         return (0);
1793 }
1794 
1795 /*
1796  * Though the actual stack base is constant, slew the %sp by a random aligned
1797  * amount in [0,aslr_max_stack_skew).  Mostly, this makes life slightly more
1798  * complicated for buffer overflows hoping to overwrite the return address.
1799  *
1800  * On some platforms this helps avoid cache thrashing when identical processes
1801  * simultaneously share caches that don't provide enough associativity
1802  * (e.g. sun4v systems). In this case stack slewing makes the same hot stack
1803  * variables in different processes live in different cache sets increasing
1804  * effective associativity.
1805  */
1806 size_t
1807 exec_get_spslew(void)
1808 {
1809 #ifdef sun4v
1810         static uint_t sp_color_stride = 16;
1811         static uint_t sp_color_mask = 0x1f;
1812         static uint_t sp_current_color = (uint_t)-1;
1813 #endif
1814         size_t off;
1815 
1816         ASSERT(ISP2(aslr_max_stack_skew));
1817 
1818         if ((aslr_max_stack_skew == 0) ||
1819             !secflag_enabled(curproc, PROC_SEC_ASLR)) {
1820 #ifdef sun4v
1821                 uint_t spcolor = atomic_inc_32_nv(&sp_current_color);
1822                 return ((size_t)((spcolor & sp_color_mask) * SA(sp_color_stride)));
1823 #else
1824                 return (0);
1825 #endif
1826         }
1827 
1828         (void) random_get_pseudo_bytes((uint8_t *)&off, sizeof (off));
1829         return SA(P2PHASE(off, aslr_max_stack_skew));
1830 }
1831 
1832 /*
1833  * Initialize a new user stack with the specified arguments and environment.
1834  * The initial user stack layout is as follows:
1835  *
1836  *      User Stack
1837  *      +---------------+ <--- curproc->p_usrstack
1838  *      |               |
1839  *      | slew          |
1840  *      |               |
1841  *      +---------------+
1842  *      | NULL          |
1843  *      +---------------+
1844  *      |               |
1845  *      | auxv strings  |
1846  *      |               |
1847  *      +---------------+
1848  *      |               |
1849  *      | envp strings  |
1850  *      |               |
1851  *      +---------------+
1852  *      |               |
1853  *      | argv strings  |
1854  *      |               |
1855  *      +---------------+ <--- ustrp
1856  *      |               |
1857  *      | aux vector    |
1858  *      |               |
1859  *      +---------------+ <--- auxv
1860  *      | NULL          |
1861  *      +---------------+
1862  *      | envp[envc-1]  |
1863  *      +---------------+
1864  *      | ...           |
1865  *      +---------------+
1866  *      | envp[0]       |
1867  *      +---------------+ <--- envp[]
1868  *      | NULL          |
1869  *      +---------------+
1870  *      | argv[argc-1]  |
1871  *      +---------------+
1872  *      | ...           |
1873  *      +---------------+
1874  *      | argv[0]       |
1875  *      +---------------+ <--- argv[]
1876  *      | argc          |
1877  *      +---------------+ <--- stack base
1878  */
1879 int
1880 exec_args(execa_t *uap, uarg_t *args, intpdata_t *intp, void **auxvpp)
1881 {
1882         size_t size;
1883         int error;
1884         proc_t *p = ttoproc(curthread);
1885         user_t *up = PTOU(p);
1886         char *usrstack;
1887         rctl_entity_p_t e;
1888         struct as *as;
1889         extern int use_stk_lpg;
1890         size_t sp_slew;
1891 
1892         args->from_model = p->p_model;
1893         if (p->p_model == DATAMODEL_NATIVE) {
1894                 args->from_ptrsize = sizeof (long);
1895         } else {
1896                 args->from_ptrsize = sizeof (int32_t);
1897         }
1898 
1899         if (args->to_model == DATAMODEL_NATIVE) {
1900                 args->to_ptrsize = sizeof (long);
1901                 args->ncargs = NCARGS;
1902                 args->stk_align = STACK_ALIGN;
1903                 if (args->addr32)
1904                         usrstack = (char *)USRSTACK64_32;
1905                 else
1906                         usrstack = (char *)USRSTACK;
1907         } else {
1908                 args->to_ptrsize = sizeof (int32_t);
1909                 args->ncargs = NCARGS32;
1910                 args->stk_align = STACK_ALIGN32;
1911                 usrstack = (char *)USRSTACK32;
1912         }
1913 
1914         ASSERT(P2PHASE((uintptr_t)usrstack, args->stk_align) == 0);
1915 
1916 #if defined(__sparc)
1917         /*
1918          * Make sure user register windows are empty before
1919          * attempting to make a new stack.
1920          */
1921         (void) flush_user_windows_to_stack(NULL);
1922 #endif
1923 
1924         for (size = PAGESIZE; ; size *= 2) {
1925                 args->stk_size = size;
1926                 args->stk_base = kmem_alloc(size, KM_SLEEP);
1927                 args->stk_strp = args->stk_base;
1928                 args->stk_offp = (int *)(args->stk_base + size);
1929                 error = stk_copyin(uap, args, intp, auxvpp);
1930                 if (error == 0)
1931                         break;
1932                 kmem_free(args->stk_base, size);
1933                 if (error != E2BIG && error != ENAMETOOLONG)
1934                         return (error);
1935                 if (size >= args->ncargs)
1936                         return (E2BIG);
1937         }
1938 
1939         size = args->usrstack_size;
1940 
1941         ASSERT(error == 0);
1942         ASSERT(P2PHASE(size, args->stk_align) == 0);
1943         ASSERT((ssize_t)STK_AVAIL(args) >= 0);
1944 
1945         if (size > args->ncargs) {
1946                 kmem_free(args->stk_base, args->stk_size);
1947                 return (E2BIG);
1948         }
1949 
1950         /*
1951          * Leave only the current lwp and force the other lwps to exit.
1952          * If another lwp beat us to the punch by calling exit(), bail out.
1953          */
1954         if ((error = exitlwps(0)) != 0) {
1955                 kmem_free(args->stk_base, args->stk_size);
1956                 return (error);
1957         }
1958 
1959         /*
1960          * Revoke any doors created by the process.
1961          */
1962         if (p->p_door_list)
1963                 door_exit();
1964 
1965         /*
1966          * Release schedctl data structures.
1967          */
1968         if (p->p_pagep)
1969                 schedctl_proc_cleanup();
1970 
1971         /*
1972          * Clean up any DTrace helpers for the process.
1973          */
1974         if (p->p_dtrace_helpers != NULL) {
1975                 ASSERT(dtrace_helpers_cleanup != NULL);
1976                 (*dtrace_helpers_cleanup)();
1977         }
1978 
1979         mutex_enter(&p->p_lock);
1980         /*
1981          * Cleanup the DTrace provider associated with this process.
1982          */
1983         if (p->p_dtrace_probes) {
1984                 ASSERT(dtrace_fasttrap_exec_ptr != NULL);
1985                 dtrace_fasttrap_exec_ptr(p);
1986         }
1987         mutex_exit(&p->p_lock);
1988 
1989         /*
1990          * discard the lwpchan cache.
1991          */
1992         if (p->p_lcp != NULL)
1993                 lwpchan_destroy_cache(1);
1994 
1995         /*
1996          * Delete the POSIX timers.
1997          */
1998         if (p->p_itimer != NULL)
1999                 timer_exit();
2000 
2001         /*
2002          * Delete the ITIMER_REALPROF interval timer.
2003          * The other ITIMER_* interval timers are specified
2004          * to be inherited across exec().
2005          */
2006         delete_itimer_realprof();
2007 
2008         if (AU_AUDITING())
2009                 audit_exec(args->stk_base, args->stk_base + args->arglen,
2010                     args->na - args->ne, args->ne, args->pfcred);
2011 
2012         /*
2013          * Ensure that we don't change resource associations while we
2014          * change address spaces.
2015          */
2016         mutex_enter(&p->p_lock);
2017         pool_barrier_enter();
2018         mutex_exit(&p->p_lock);
2019 
2020         /*
2021          * Destroy the old address space and create a new one.
2022          * From here on, any errors are fatal to the exec()ing process.
2023          * On error we return -1, which means the caller must SIGKILL
2024          * the process.
2025          */
2026         relvm();
2027 
2028         mutex_enter(&p->p_lock);
2029         pool_barrier_exit();
2030         mutex_exit(&p->p_lock);
2031 
2032         up->u_execsw = args->execswp;
2033 
2034         p->p_brkbase = NULL;
2035         p->p_brksize = 0;
2036         p->p_brkpageszc = 0;
2037         p->p_stksize = 0;
2038         p->p_stkpageszc = 0;
2039         p->p_model = args->to_model;
2040         p->p_usrstack = usrstack;
2041         p->p_stkprot = args->stk_prot;
2042         p->p_datprot = args->dat_prot;
2043 
2044         /*
2045          * Reset resource controls such that all controls are again active as
2046          * well as appropriate to the potentially new address model for the
2047          * process.
2048          */
2049         e.rcep_p.proc = p;
2050         e.rcep_t = RCENTITY_PROCESS;
2051         rctl_set_reset(p->p_rctls, p, &e);
2052 
2053         /* Too early to call map_pgsz for the heap */
2054         if (use_stk_lpg) {
2055                 p->p_stkpageszc = page_szc(map_pgsz(MAPPGSZ_STK, p, 0, 0, 0));
2056         }
2057 
2058         mutex_enter(&p->p_lock);
2059         p->p_flag |= SAUTOLPG;       /* kernel controls page sizes */
2060         mutex_exit(&p->p_lock);
2061 
2062         sp_slew = exec_get_spslew();
2063         ASSERT(P2PHASE(sp_slew, args->stk_align) == 0);
2064         /* Be certain we don't underflow */
2065         VERIFY((curproc->p_usrstack - (size + sp_slew)) < curproc->p_usrstack);
2066         exec_set_sp(size + sp_slew);
2067 
2068         as = as_alloc();
2069         p->p_as = as;
2070         as->a_proc = p;
2071         if (p->p_model == DATAMODEL_ILP32 || args->addr32)
2072                 as->a_userlimit = (caddr_t)USERLIMIT32;
2073         (void) hat_setup(as->a_hat, HAT_ALLOC);
2074         hat_join_srd(as->a_hat, args->ex_vp);
2075 
2076         /*
2077          * Finally, write out the contents of the new stack.
2078          */
2079         error = stk_copyout(args, usrstack - sp_slew, auxvpp, up);
2080         kmem_free(args->stk_base, args->stk_size);
2081         return (error);
2082 }