/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #pragma ident "%Z%%M% %I% %E% SMI" /* Copyright (c) 1988 AT&T */ /* All Rights Reserved */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define PRIV_RESET 0x01 /* needs to reset privs */ #define PRIV_SETID 0x02 /* needs to change uids */ #define PRIV_SETUGID 0x04 /* is setuid/setgid/forced privs */ #define PRIV_INCREASE 0x08 /* child runs with more privs */ #define MAC_FLAGS 0x10 /* need to adjust MAC flags */ static int execsetid(struct vnode *, struct vattr *, uid_t *, uid_t *); static int hold_execsw(struct execsw *); uint_t auxv_hwcap = 0; /* auxv AT_SUN_HWCAP value; determined on the fly */ #if defined(_SYSCALL32_IMPL) uint_t auxv_hwcap32 = 0; /* 32-bit version of auxv_hwcap */ #endif #define PSUIDFLAGS (SNOCD|SUGID) /* * exec() - wrapper around exece providing NULL environment pointer */ int exec(const char *fname, const char **argp) { return (exece(fname, argp, NULL)); } /* * exece() - system call wrapper around exec_common() */ int exece(const char *fname, const char **argp, const char **envp) { int error; error = exec_common(fname, argp, envp, EBA_NONE); return (error ? (set_errno(error)) : 0); } int exec_common(const char *fname, const char **argp, const char **envp, int brand_action) { vnode_t *vp = NULL, *dir = NULL, *tmpvp = NULL; proc_t *p = ttoproc(curthread); klwp_t *lwp = ttolwp(curthread); struct user *up = PTOU(p); long execsz; /* temporary count of exec size */ int i; int error; char exec_file[MAXCOMLEN+1]; struct pathname pn; struct pathname resolvepn; struct uarg args; struct execa ua; k_sigset_t savedmask; lwpdir_t *lwpdir = NULL; lwpdir_t **tidhash; lwpdir_t *old_lwpdir = NULL; uint_t old_lwpdir_sz; lwpdir_t **old_tidhash; uint_t old_tidhash_sz; lwpent_t *lep; int brandme = 0; /* * exec() is not supported for the /proc agent lwp. */ if (curthread == p->p_agenttp) return (ENOTSUP); if ((error = secpolicy_basic_exec(CRED())) != 0) return (error); if (brand_action != EBA_NONE) { /* * Brand actions are not supported for processes that are not * running in a branded zone. */ if (!ZONE_IS_BRANDED(p->p_zone)) return (ENOTSUP); if (brand_action == EBA_NATIVE) { /* Only branded processes can be unbranded */ if (!PROC_IS_BRANDED(p)) return (ENOTSUP); } else { /* Only unbranded processes can be branded */ if (PROC_IS_BRANDED(p)) return (ENOTSUP); brandme = 1; } } else { /* * If this is a native zone, or if the process is already * branded, then we don't need to do anything. If this is * a native process in a branded zone, we need to brand the * process as it exec()s the new binary. */ if (ZONE_IS_BRANDED(p->p_zone) && !PROC_IS_BRANDED(p)) brandme = 1; } /* * Inform /proc that an exec() has started. * Hold signals that are ignored by default so that we will * not be interrupted by a signal that will be ignored after * successful completion of gexec(). */ mutex_enter(&p->p_lock); prexecstart(); schedctl_finish_sigblock(curthread); savedmask = curthread->t_hold; sigorset(&curthread->t_hold, &ignoredefault); mutex_exit(&p->p_lock); /* * Look up path name and remember last component for later. * To help coreadm expand its %d token, we attempt to save * the directory containing the executable in p_execdir. The * first call to lookuppn() may fail and return EINVAL because * dirvpp is non-NULL. In that case, we make a second call to * lookuppn() with dirvpp set to NULL; p_execdir will be NULL, * but coreadm is allowed to expand %d to the empty string and * there are other cases in which that failure may occur. */ if ((error = pn_get((char *)fname, UIO_USERSPACE, &pn)) != 0) goto out; pn_alloc(&resolvepn); if ((error = lookuppn(&pn, &resolvepn, FOLLOW, &dir, &vp)) != 0) { pn_free(&resolvepn); pn_free(&pn); if (error != EINVAL) goto out; dir = NULL; if ((error = pn_get((char *)fname, UIO_USERSPACE, &pn)) != 0) goto out; pn_alloc(&resolvepn); if ((error = lookuppn(&pn, &resolvepn, FOLLOW, NULLVPP, &vp)) != 0) { pn_free(&resolvepn); pn_free(&pn); goto out; } } if (vp == NULL) { if (dir != NULL) VN_RELE(dir); error = ENOENT; pn_free(&resolvepn); pn_free(&pn); goto out; } /* * We do not allow executing files in attribute directories. * We test this by determining whether the resolved path * contains a "/" when we're in an attribute directory; * only if the pathname does not contain a "/" the resolved path * points to a file in the current working (attribute) directory. */ if ((p->p_user.u_cdir->v_flag & V_XATTRDIR) != 0 && strchr(resolvepn.pn_path, '/') == NULL) { if (dir != NULL) VN_RELE(dir); error = EACCES; pn_free(&resolvepn); pn_free(&pn); VN_RELE(vp); goto out; } bzero(exec_file, MAXCOMLEN+1); (void) strncpy(exec_file, pn.pn_path, MAXCOMLEN); bzero(&args, sizeof (args)); args.pathname = resolvepn.pn_path; /* don't free resolvepn until we are done with args */ pn_free(&pn); /* * Specific exec handlers, or policies determined via * /etc/system may override the historical default. */ args.stk_prot = PROT_ZFOD; args.dat_prot = PROT_ZFOD; CPU_STATS_ADD_K(sys, sysexec, 1); DTRACE_PROC1(exec, char *, args.pathname); ua.fname = fname; ua.argp = argp; ua.envp = envp; /* If necessary, brand this process before we start the exec. */ if (brandme != 0) brand_setbrand(p); if ((error = gexec(&vp, &ua, &args, NULL, 0, &execsz, exec_file, p->p_cred, brand_action)) != 0) { if (brandme != 0) BROP(p)->b_proc_exit(p, lwp); VN_RELE(vp); if (dir != NULL) VN_RELE(dir); pn_free(&resolvepn); goto fail; } /* * Free floating point registers (sun4u only) */ ASSERT(lwp != NULL); lwp_freeregs(lwp, 1); /* * Free thread and process context ops. */ if (curthread->t_ctx) freectx(curthread, 1); if (p->p_pctx) freepctx(p, 1); /* * Remember file name for accounting; clear any cached DTrace predicate. */ up->u_acflag &= ~AFORK; bcopy(exec_file, up->u_comm, MAXCOMLEN+1); curthread->t_predcache = NULL; /* * Clear contract template state */ lwp_ctmpl_clear(lwp); /* * Save the directory in which we found the executable for expanding * the %d token used in core file patterns. */ mutex_enter(&p->p_lock); tmpvp = p->p_execdir; p->p_execdir = dir; if (p->p_execdir != NULL) VN_HOLD(p->p_execdir); mutex_exit(&p->p_lock); if (tmpvp != NULL) VN_RELE(tmpvp); /* * Reset stack state to the user stack, clear set of signals * caught on the signal stack, and reset list of signals that * restart system calls; the new program's environment should * not be affected by detritus from the old program. Any * pending held signals remain held, so don't clear t_hold. */ mutex_enter(&p->p_lock); lwp->lwp_oldcontext = 0; lwp->lwp_ustack = 0; lwp->lwp_old_stk_ctl = 0; sigemptyset(&up->u_signodefer); sigemptyset(&up->u_sigonstack); sigemptyset(&up->u_sigresethand); lwp->lwp_sigaltstack.ss_sp = 0; lwp->lwp_sigaltstack.ss_size = 0; lwp->lwp_sigaltstack.ss_flags = SS_DISABLE; /* * Make saved resource limit == current resource limit. */ for (i = 0; i < RLIM_NLIMITS; i++) { /*CONSTCOND*/ if (RLIM_SAVED(i)) { (void) rctl_rlimit_get(rctlproc_legacy[i], p, &up->u_saved_rlimit[i]); } } /* * If the action was to catch the signal, then the action * must be reset to SIG_DFL. */ sigdefault(p); p->p_flag &= ~(SNOWAIT|SJCTL); p->p_flag |= (SEXECED|SMSACCT|SMSFORK); up->u_signal[SIGCLD - 1] = SIG_DFL; /* * Delete the dot4 sigqueues/signotifies. */ sigqfree(p); mutex_exit(&p->p_lock); mutex_enter(&p->p_pflock); p->p_prof.pr_base = NULL; p->p_prof.pr_size = 0; p->p_prof.pr_off = 0; p->p_prof.pr_scale = 0; p->p_prof.pr_samples = 0; mutex_exit(&p->p_pflock); ASSERT(curthread->t_schedctl == NULL); #if defined(__sparc) if (p->p_utraps != NULL) utrap_free(p); #endif /* __sparc */ /* * Close all close-on-exec files. */ close_exec(P_FINFO(p)); TRACE_2(TR_FAC_PROC, TR_PROC_EXEC, "proc_exec:p %p up %p", p, up); /* Unbrand ourself if requested. */ if (brand_action == EBA_NATIVE) BROP(p)->b_proc_exit(p, lwp); ASSERT((brand_action != EBA_NATIVE) || !PROC_IS_BRANDED(p)); setregs(&args); /* Mark this as an executable vnode */ mutex_enter(&vp->v_lock); vp->v_flag |= VVMEXEC; mutex_exit(&vp->v_lock); VN_RELE(vp); if (dir != NULL) VN_RELE(dir); pn_free(&resolvepn); /* * Allocate a new lwp directory and lwpid hash table if necessary. */ if (curthread->t_tid != 1 || p->p_lwpdir_sz != 2) { lwpdir = kmem_zalloc(2 * sizeof (lwpdir_t), KM_SLEEP); lwpdir->ld_next = lwpdir + 1; tidhash = kmem_zalloc(2 * sizeof (lwpdir_t *), KM_SLEEP); if (p->p_lwpdir != NULL) lep = p->p_lwpdir[curthread->t_dslot].ld_entry; else lep = kmem_zalloc(sizeof (*lep), KM_SLEEP); } if (PROC_IS_BRANDED(p)) BROP(p)->b_exec(); mutex_enter(&p->p_lock); prbarrier(p); /* * Reset lwp id to the default value of 1. * This is a single-threaded process now * and lwp #1 is lwp_wait()able by default. * The t_unpark flag should not be inherited. */ ASSERT(p->p_lwpcnt == 1 && p->p_zombcnt == 0); curthread->t_tid = 1; curthread->t_unpark = 0; curthread->t_proc_flag |= TP_TWAIT; curthread->t_proc_flag &= ~TP_DAEMON; /* daemons shouldn't exec */ p->p_lwpdaemon = 0; /* but oh well ... */ p->p_lwpid = 1; /* * Install the newly-allocated lwp directory and lwpid hash table * and insert the current thread into the new hash table. */ if (lwpdir != NULL) { old_lwpdir = p->p_lwpdir; old_lwpdir_sz = p->p_lwpdir_sz; old_tidhash = p->p_tidhash; old_tidhash_sz = p->p_tidhash_sz; p->p_lwpdir = p->p_lwpfree = lwpdir; p->p_lwpdir_sz = 2; p->p_tidhash = tidhash; p->p_tidhash_sz = 2; lep->le_thread = curthread; lep->le_lwpid = curthread->t_tid; lep->le_start = curthread->t_start; lwp_hash_in(p, lep); } /* * Restore the saved signal mask and * inform /proc that the exec() has finished. */ curthread->t_hold = savedmask; prexecend(); mutex_exit(&p->p_lock); if (old_lwpdir) { kmem_free(old_lwpdir, old_lwpdir_sz * sizeof (lwpdir_t)); kmem_free(old_tidhash, old_tidhash_sz * sizeof (lwpdir_t *)); } ASSERT(error == 0); DTRACE_PROC(exec__success); return (0); fail: DTRACE_PROC1(exec__failure, int, error); out: /* error return */ mutex_enter(&p->p_lock); curthread->t_hold = savedmask; prexecend(); mutex_exit(&p->p_lock); ASSERT(error != 0); return (error); } /* * Perform generic exec duties and switchout to object-file specific * handler. */ int gexec( struct vnode **vpp, struct execa *uap, struct uarg *args, struct intpdata *idatap, int level, long *execsz, caddr_t exec_file, struct cred *cred, int brand_action) { struct vnode *vp; proc_t *pp = ttoproc(curthread); struct execsw *eswp; int error = 0; int suidflags = 0; ssize_t resid; uid_t uid, gid; struct vattr vattr; char magbuf[MAGIC_BYTES]; int setid; cred_t *oldcred, *newcred = NULL; int privflags = 0; int setidfl; /* * If the SNOCD or SUGID flag is set, turn it off and remember the * previous setting so we can restore it if we encounter an error. */ if (level == 0 && (pp->p_flag & PSUIDFLAGS)) { mutex_enter(&pp->p_lock); suidflags = pp->p_flag & PSUIDFLAGS; pp->p_flag &= ~PSUIDFLAGS; mutex_exit(&pp->p_lock); } if ((error = execpermissions(*vpp, &vattr, args)) != 0) goto bad; /* need to open vnode for stateful file systems like rfs */ if ((error = VOP_OPEN(vpp, FREAD, CRED())) != 0) goto bad; vp = *vpp; /* * Note: to support binary compatibility with SunOS a.out * executables, we read in the first four bytes, as the * magic number is in bytes 2-3. */ if (error = vn_rdwr(UIO_READ, vp, magbuf, sizeof (magbuf), (offset_t)0, UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid)) goto bad; if (resid != 0) goto bad; if ((eswp = findexec_by_hdr(magbuf)) == NULL) goto bad; if (level == 0 && (privflags = execsetid(vp, &vattr, &uid, &gid)) != 0) { newcred = cred = crdup(cred); /* If we can, drop the PA bit */ if ((privflags & PRIV_RESET) != 0) priv_adjust_PA(cred); if (privflags & PRIV_SETID) { cred->cr_uid = uid; cred->cr_gid = gid; cred->cr_suid = uid; cred->cr_sgid = gid; } if (privflags & MAC_FLAGS) { if (!(CR_FLAGS(cred) & NET_MAC_AWARE_INHERIT)) CR_FLAGS(cred) &= ~NET_MAC_AWARE; CR_FLAGS(cred) &= ~NET_MAC_AWARE_INHERIT; } /* * Implement the privilege updates: * * Restrict with L: * * I' = I & L * * E' = P' = (I' + F) & A * * But if running under ptrace, we cap I with P. */ if ((privflags & PRIV_RESET) != 0) { if ((privflags & PRIV_INCREASE) != 0 && (pp->p_proc_flag & P_PR_PTRACE) != 0) priv_intersect(&CR_OPPRIV(cred), &CR_IPRIV(cred)); priv_intersect(&CR_LPRIV(cred), &CR_IPRIV(cred)); CR_EPRIV(cred) = CR_PPRIV(cred) = CR_IPRIV(cred); priv_adjust_PA(cred); } } /* SunOS 4.x buy-back */ if ((vp->v_vfsp->vfs_flag & VFS_NOSETUID) && (vattr.va_mode & (VSUID|VSGID))) { cmn_err(CE_NOTE, "!%s, uid %d: setuid execution not allowed, dev=%lx", exec_file, cred->cr_uid, vp->v_vfsp->vfs_dev); } /* * execsetid() told us whether or not we had to change the * credentials of the process. In privflags, it told us * whether we gained any privileges or executed a set-uid executable. */ setid = (privflags & (PRIV_SETUGID|PRIV_INCREASE)); /* * Use /etc/system variable to determine if the stack * should be marked as executable by default. */ if (noexec_user_stack) args->stk_prot &= ~PROT_EXEC; args->execswp = eswp; /* Save execsw pointer in uarg for exec_func */ /* * Traditionally, the setid flags told the sub processes whether * the file just executed was set-uid or set-gid; this caused * some confusion as the 'setid' flag did not match the SUGID * process flag which is only set when the uids/gids do not match. * A script set-gid/set-uid to the real uid/gid would start with * /dev/fd/X but an executable would happily trust LD_LIBRARY_PATH. * Now we flag those cases where the calling process cannot * be trusted to influence the newly exec'ed process, either * because it runs with more privileges or when the uids/gids * do in fact not match. * This also makes the runtime linker agree with the on exec * values of SNOCD and SUGID. */ setidfl = 0; if (cred->cr_uid != cred->cr_ruid || (cred->cr_rgid != cred->cr_gid && !supgroupmember(cred->cr_gid, cred))) { setidfl |= EXECSETID_UGIDS; } if (setid & PRIV_SETUGID) setidfl |= EXECSETID_SETID; if (setid & PRIV_INCREASE) setidfl |= EXECSETID_PRIVS; error = (*eswp->exec_func)(vp, uap, args, idatap, level, execsz, setidfl, exec_file, cred, brand_action); rw_exit(eswp->exec_lock); if (error != 0) { if (newcred != NULL) crfree(newcred); goto bad; } if (level == 0) { mutex_enter(&pp->p_crlock); if (newcred != NULL) { /* * Free the old credentials, and set the new ones. * Do this for both the process and the (single) thread. */ crfree(pp->p_cred); pp->p_cred = cred; /* cred already held for proc */ crhold(cred); /* hold new cred for thread */ /* * DTrace accesses t_cred in probe context. t_cred * must always be either NULL, or point to a valid, * allocated cred structure. */ oldcred = curthread->t_cred; curthread->t_cred = cred; crfree(oldcred); } /* * On emerging from a successful exec(), the saved * uid and gid equal the effective uid and gid. */ cred->cr_suid = cred->cr_uid; cred->cr_sgid = cred->cr_gid; /* * If the real and effective ids do not match, this * is a setuid process that should not dump core. * The group comparison is tricky; we prevent the code * from flagging SNOCD when executing with an effective gid * which is a supplementary group. */ if (cred->cr_ruid != cred->cr_uid || (cred->cr_rgid != cred->cr_gid && !supgroupmember(cred->cr_gid, cred)) || (privflags & PRIV_INCREASE) != 0) suidflags = PSUIDFLAGS; else suidflags = 0; mutex_exit(&pp->p_crlock); if (suidflags) { mutex_enter(&pp->p_lock); pp->p_flag |= suidflags; mutex_exit(&pp->p_lock); } if (setid && (pp->p_proc_flag & P_PR_PTRACE) == 0) { /* * If process is traced via /proc, arrange to * invalidate the associated /proc vnode. */ if (pp->p_plist || (pp->p_proc_flag & P_PR_TRACE)) args->traceinval = 1; } if (pp->p_proc_flag & P_PR_PTRACE) psignal(pp, SIGTRAP); if (args->traceinval) prinvalidate(&pp->p_user); } return (0); bad: if (error == 0) error = ENOEXEC; if (suidflags) { mutex_enter(&pp->p_lock); pp->p_flag |= suidflags; mutex_exit(&pp->p_lock); } return (error); } extern char *execswnames[]; struct execsw * allocate_execsw(char *name, char *magic, size_t magic_size) { int i, j; char *ename; char *magicp; mutex_enter(&execsw_lock); for (i = 0; i < nexectype; i++) { if (execswnames[i] == NULL) { ename = kmem_alloc(strlen(name) + 1, KM_SLEEP); (void) strcpy(ename, name); execswnames[i] = ename; /* * Set the magic number last so that we * don't need to hold the execsw_lock in * findexectype(). */ magicp = kmem_alloc(magic_size, KM_SLEEP); for (j = 0; j < magic_size; j++) magicp[j] = magic[j]; execsw[i].exec_magic = magicp; mutex_exit(&execsw_lock); return (&execsw[i]); } } mutex_exit(&execsw_lock); return (NULL); } /* * Find the exec switch table entry with the corresponding magic string. */ struct execsw * findexecsw(char *magic) { struct execsw *eswp; for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) { ASSERT(eswp->exec_maglen <= MAGIC_BYTES); if (magic && eswp->exec_maglen != 0 && bcmp(magic, eswp->exec_magic, eswp->exec_maglen) == 0) return (eswp); } return (NULL); } /* * Find the execsw[] index for the given exec header string by looking for the * magic string at a specified offset and length for each kind of executable * file format until one matches. If no execsw[] entry is found, try to * autoload a module for this magic string. */ struct execsw * findexec_by_hdr(char *header) { struct execsw *eswp; for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) { ASSERT(eswp->exec_maglen <= MAGIC_BYTES); if (header && eswp->exec_maglen != 0 && bcmp(&header[eswp->exec_magoff], eswp->exec_magic, eswp->exec_maglen) == 0) { if (hold_execsw(eswp) != 0) return (NULL); return (eswp); } } return (NULL); /* couldn't find the type */ } /* * Find the execsw[] index for the given magic string. If no execsw[] entry * is found, try to autoload a module for this magic string. */ struct execsw * findexec_by_magic(char *magic) { struct execsw *eswp; for (eswp = execsw; eswp < &execsw[nexectype]; eswp++) { ASSERT(eswp->exec_maglen <= MAGIC_BYTES); if (magic && eswp->exec_maglen != 0 && bcmp(magic, eswp->exec_magic, eswp->exec_maglen) == 0) { if (hold_execsw(eswp) != 0) return (NULL); return (eswp); } } return (NULL); /* couldn't find the type */ } static int hold_execsw(struct execsw *eswp) { char *name; rw_enter(eswp->exec_lock, RW_READER); while (!LOADED_EXEC(eswp)) { rw_exit(eswp->exec_lock); name = execswnames[eswp-execsw]; ASSERT(name); if (modload("exec", name) == -1) return (-1); rw_enter(eswp->exec_lock, RW_READER); } return (0); } static int execsetid(struct vnode *vp, struct vattr *vattrp, uid_t *uidp, uid_t *gidp) { proc_t *pp = ttoproc(curthread); uid_t uid, gid; cred_t *cr = pp->p_cred; int privflags = 0; /* * Remember credentials. */ uid = cr->cr_uid; gid = cr->cr_gid; /* Will try to reset the PRIV_AWARE bit later. */ if ((CR_FLAGS(cr) & (PRIV_AWARE|PRIV_AWARE_INHERIT)) == PRIV_AWARE) privflags |= PRIV_RESET; if ((vp->v_vfsp->vfs_flag & VFS_NOSETUID) == 0) { /* * Set-uid root execution only allowed if the limit set * holds all unsafe privileges. */ if ((vattrp->va_mode & VSUID) && (vattrp->va_uid != 0 || priv_issubset(&priv_unsafe, &CR_LPRIV(cr)))) { uid = vattrp->va_uid; privflags |= PRIV_SETUGID; } if (vattrp->va_mode & VSGID) { gid = vattrp->va_gid; privflags |= PRIV_SETUGID; } } /* * Do we need to change our credential anyway? * This is the case when E != I or P != I, as * we need to do the assignments (with F empty and A full) * Or when I is not a subset of L; in that case we need to * enforce L. * * I' = L & I * * E' = P' = (I' + F) & A * or * E' = P' = I' */ if (!priv_isequalset(&CR_EPRIV(cr), &CR_IPRIV(cr)) || !priv_issubset(&CR_IPRIV(cr), &CR_LPRIV(cr)) || !priv_isequalset(&CR_PPRIV(cr), &CR_IPRIV(cr))) privflags |= PRIV_RESET; /* If MAC-aware flag(s) are on, need to update cred to remove. */ if ((CR_FLAGS(cr) & NET_MAC_AWARE) || (CR_FLAGS(cr) & NET_MAC_AWARE_INHERIT)) privflags |= MAC_FLAGS; /* * When we introduce the "forced" set then we will need * to set PRIV_INCREASE here if I not a subset of P. * If the "allowed" set is introduced we will need to do * a similar thing; however, it seems more reasonable to * have the allowed set reduce "L": script language interpreters * would typically have an allowed set of "all". */ /* * Set setuid/setgid protections if no ptrace() compatibility. * For privileged processes, honor setuid/setgid even in * the presence of ptrace() compatibility. */ if (((pp->p_proc_flag & P_PR_PTRACE) == 0 || PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, (uid == 0))) && (cr->cr_uid != uid || cr->cr_gid != gid || cr->cr_suid != uid || cr->cr_sgid != gid)) { *uidp = uid; *gidp = gid; privflags |= PRIV_SETID; } return (privflags); } int execpermissions(struct vnode *vp, struct vattr *vattrp, struct uarg *args) { int error; proc_t *p = ttoproc(curthread); vattrp->va_mask = AT_MODE | AT_UID | AT_GID | AT_SIZE; if (error = VOP_GETATTR(vp, vattrp, ATTR_EXEC, p->p_cred)) return (error); /* * Check the access mode. * If VPROC, ask /proc if the file is an object file. */ if ((error = VOP_ACCESS(vp, VEXEC, 0, p->p_cred)) != 0 || !(vp->v_type == VREG || (vp->v_type == VPROC && pr_isobject(vp))) || (vp->v_vfsp->vfs_flag & VFS_NOEXEC) != 0 || (vattrp->va_mode & (VEXEC|(VEXEC>>3)|(VEXEC>>6))) == 0) { if (error == 0) error = EACCES; return (error); } if ((p->p_plist || (p->p_proc_flag & (P_PR_PTRACE|P_PR_TRACE))) && (error = VOP_ACCESS(vp, VREAD, 0, p->p_cred))) { /* * If process is under ptrace(2) compatibility, * fail the exec(2). */ if (p->p_proc_flag & P_PR_PTRACE) goto bad; /* * Process is traced via /proc. * Arrange to invalidate the /proc vnode. */ args->traceinval = 1; } return (0); bad: if (error == 0) error = ENOEXEC; return (error); } /* * Map a section of an executable file into the user's * address space. */ int execmap(struct vnode *vp, caddr_t addr, size_t len, size_t zfodlen, off_t offset, int prot, int page, uint_t szc) { int error = 0; off_t oldoffset; caddr_t zfodbase, oldaddr; size_t end, oldlen; size_t zfoddiff; label_t ljb; proc_t *p = ttoproc(curthread); oldaddr = addr; addr = (caddr_t)((uintptr_t)addr & (uintptr_t)PAGEMASK); if (len) { oldlen = len; len += ((size_t)oldaddr - (size_t)addr); oldoffset = offset; offset = (off_t)((uintptr_t)offset & PAGEMASK); if (page) { spgcnt_t prefltmem, availm, npages; int preread; uint_t mflag = MAP_PRIVATE | MAP_FIXED; if ((prot & (PROT_WRITE | PROT_EXEC)) == PROT_EXEC) { mflag |= MAP_TEXT; } else { mflag |= MAP_INITDATA; } if (valid_usr_range(addr, len, prot, p->p_as, p->p_as->a_userlimit) != RANGE_OKAY) { error = ENOMEM; goto bad; } if (error = VOP_MAP(vp, (offset_t)offset, p->p_as, &addr, len, prot, PROT_ALL, mflag, CRED())) goto bad; /* * If the segment can fit, then we prefault * the entire segment in. This is based on the * model that says the best working set of a * small program is all of its pages. */ npages = (spgcnt_t)btopr(len); prefltmem = freemem - desfree; preread = (npages < prefltmem && len < PGTHRESH) ? 1 : 0; /* * If we aren't prefaulting the segment, * increment "deficit", if necessary to ensure * that pages will become available when this * process starts executing. */ availm = freemem - lotsfree; if (preread == 0 && npages > availm && deficit < lotsfree) { deficit += MIN((pgcnt_t)(npages - availm), lotsfree - deficit); } if (preread) { TRACE_2(TR_FAC_PROC, TR_EXECMAP_PREREAD, "execmap preread:freemem %d size %lu", freemem, len); (void) as_fault(p->p_as->a_hat, p->p_as, (caddr_t)addr, len, F_INVAL, S_READ); } } else { if (valid_usr_range(addr, len, prot, p->p_as, p->p_as->a_userlimit) != RANGE_OKAY) { error = ENOMEM; goto bad; } if (error = as_map(p->p_as, addr, len, segvn_create, zfod_argsp)) goto bad; /* * Read in the segment in one big chunk. */ if (error = vn_rdwr(UIO_READ, vp, (caddr_t)oldaddr, oldlen, (offset_t)oldoffset, UIO_USERSPACE, 0, (rlim64_t)0, CRED(), (ssize_t *)0)) goto bad; /* * Now set protections. */ if (prot != PROT_ZFOD) { (void) as_setprot(p->p_as, (caddr_t)addr, len, prot); } } } if (zfodlen) { struct as *as = curproc->p_as; struct seg *seg; uint_t zprot = 0; end = (size_t)addr + len; zfodbase = (caddr_t)roundup(end, PAGESIZE); zfoddiff = (uintptr_t)zfodbase - end; if (zfoddiff) { /* * Before we go to zero the remaining space on the last * page, make sure we have write permission. */ AS_LOCK_ENTER(as, &as->a_lock, RW_READER); seg = as_segat(curproc->p_as, (caddr_t)end); if (seg != NULL) SEGOP_GETPROT(seg, (caddr_t)end, zfoddiff - 1, &zprot); AS_LOCK_EXIT(as, &as->a_lock); if (seg != NULL && (zprot & PROT_WRITE) == 0) { (void) as_setprot(as, (caddr_t)end, zfoddiff - 1, zprot | PROT_WRITE); } if (on_fault(&ljb)) { no_fault(); if (seg != NULL && (zprot & PROT_WRITE) == 0) (void) as_setprot(as, (caddr_t)end, zfoddiff - 1, zprot); error = EFAULT; goto bad; } uzero((void *)end, zfoddiff); no_fault(); if (seg != NULL && (zprot & PROT_WRITE) == 0) (void) as_setprot(as, (caddr_t)end, zfoddiff - 1, zprot); } if (zfodlen > zfoddiff) { struct segvn_crargs crargs = SEGVN_ZFOD_ARGS(PROT_ZFOD, PROT_ALL); zfodlen -= zfoddiff; if (valid_usr_range(zfodbase, zfodlen, prot, p->p_as, p->p_as->a_userlimit) != RANGE_OKAY) { error = ENOMEM; goto bad; } if (szc > 0) { /* * ASSERT alignment because the mapelfexec() * caller for the szc > 0 case extended zfod * so it's end is pgsz aligned. */ size_t pgsz = page_get_pagesize(szc); ASSERT(IS_P2ALIGNED(zfodbase + zfodlen, pgsz)); if (IS_P2ALIGNED(zfodbase, pgsz)) { crargs.szc = szc; } else { crargs.szc = AS_MAP_HEAP; } } else { crargs.szc = AS_MAP_NO_LPOOB; } if (error = as_map(p->p_as, (caddr_t)zfodbase, zfodlen, segvn_create, &crargs)) goto bad; if (prot != PROT_ZFOD) { (void) as_setprot(p->p_as, (caddr_t)zfodbase, zfodlen, prot); } } } return (0); bad: return (error); } void setexecenv(struct execenv *ep) { proc_t *p = ttoproc(curthread); klwp_t *lwp = ttolwp(curthread); struct vnode *vp; p->p_bssbase = ep->ex_bssbase; p->p_brkbase = ep->ex_brkbase; p->p_brksize = ep->ex_brksize; if (p->p_exec) VN_RELE(p->p_exec); /* out with the old */ vp = p->p_exec = ep->ex_vp; if (vp != NULL) VN_HOLD(vp); /* in with the new */ lwp->lwp_sigaltstack.ss_sp = 0; lwp->lwp_sigaltstack.ss_size = 0; lwp->lwp_sigaltstack.ss_flags = SS_DISABLE; } int execopen(struct vnode **vpp, int *fdp) { struct vnode *vp = *vpp; file_t *fp; int error = 0; int filemode = FREAD; VN_HOLD(vp); /* open reference */ if (error = falloc(NULL, filemode, &fp, fdp)) { VN_RELE(vp); *fdp = -1; /* just in case falloc changed value */ return (error); } if (error = VOP_OPEN(&vp, filemode, CRED())) { VN_RELE(vp); setf(*fdp, NULL); unfalloc(fp); *fdp = -1; return (error); } *vpp = vp; /* vnode should not have changed */ fp->f_vnode = vp; mutex_exit(&fp->f_tlock); setf(*fdp, fp); return (0); } int execclose(int fd) { return (closeandsetf(fd, NULL)); } /* * noexec stub function. */ /*ARGSUSED*/ int noexec( struct vnode *vp, struct execa *uap, struct uarg *args, struct intpdata *idatap, int level, long *execsz, int setid, caddr_t exec_file, struct cred *cred) { cmn_err(CE_WARN, "missing exec capability for %s", uap->fname); return (ENOEXEC); } /* * Support routines for building a user stack. * * execve(path, argv, envp) must construct a new stack with the specified * arguments and environment variables (see exec_args() for a description * of the user stack layout). To do this, we copy the arguments and * environment variables from the old user address space into the kernel, * free the old as, create the new as, and copy our buffered information * to the new stack. Our kernel buffer has the following structure: * * +-----------------------+ <--- stk_base + stk_size * | string offsets | * +-----------------------+ <--- stk_offp * | | * | STK_AVAIL() space | * | | * +-----------------------+ <--- stk_strp * | strings | * +-----------------------+ <--- stk_base * * When we add a string, we store the string's contents (including the null * terminator) at stk_strp, and we store the offset of the string relative to * stk_base at --stk_offp. At strings are added, stk_strp increases and * stk_offp decreases. The amount of space remaining, STK_AVAIL(), is just * the difference between these pointers. If we run out of space, we return * an error and exec_args() starts all over again with a buffer twice as large. * When we're all done, the kernel buffer looks like this: * * +-----------------------+ <--- stk_base + stk_size * | argv[0] offset | * +-----------------------+ * | ... | * +-----------------------+ * | argv[argc-1] offset | * +-----------------------+ * | envp[0] offset | * +-----------------------+ * | ... | * +-----------------------+ * | envp[envc-1] offset | * +-----------------------+ * | AT_SUN_PLATFORM offset| * +-----------------------+ * | AT_SUN_EXECNAME offset| * +-----------------------+ <--- stk_offp * | | * | STK_AVAIL() space | * | | * +-----------------------+ <--- stk_strp * | AT_SUN_EXECNAME offset| * +-----------------------+ * | AT_SUN_PLATFORM offset| * +-----------------------+ * | envp[envc-1] string | * +-----------------------+ * | ... | * +-----------------------+ * | envp[0] string | * +-----------------------+ * | argv[argc-1] string | * +-----------------------+ * | ... | * +-----------------------+ * | argv[0] string | * +-----------------------+ <--- stk_base */ #define STK_AVAIL(args) ((char *)(args)->stk_offp - (args)->stk_strp) /* * Add a string to the stack. */ static int stk_add(uarg_t *args, const char *sp, enum uio_seg segflg) { int error; size_t len; if (STK_AVAIL(args) < sizeof (int)) return (E2BIG); *--args->stk_offp = args->stk_strp - args->stk_base; if (segflg == UIO_USERSPACE) { error = copyinstr(sp, args->stk_strp, STK_AVAIL(args), &len); if (error != 0) return (error); } else { len = strlen(sp) + 1; if (len > STK_AVAIL(args)) return (E2BIG); bcopy(sp, args->stk_strp, len); } args->stk_strp += len; return (0); } static int stk_getptr(uarg_t *args, char *src, char **dst) { int error; if (args->from_model == DATAMODEL_NATIVE) { ulong_t ptr; error = fulword(src, &ptr); *dst = (caddr_t)ptr; } else { uint32_t ptr; error = fuword32(src, &ptr); *dst = (caddr_t)(uintptr_t)ptr; } return (error); } static int stk_putptr(uarg_t *args, char *addr, char *value) { if (args->to_model == DATAMODEL_NATIVE) return (sulword(addr, (ulong_t)value)); else return (suword32(addr, (uint32_t)(uintptr_t)value)); } static int stk_copyin(execa_t *uap, uarg_t *args, intpdata_t *intp, void **auxvpp) { char *sp; int argc, error; int argv_empty = 0; size_t ptrsize = args->from_ptrsize; size_t size, pad; char *argv = (char *)uap->argp; char *envp = (char *)uap->envp; /* * Copy interpreter's name and argument to argv[0] and argv[1]. */ if (intp != NULL && intp->intp_name != NULL) { if ((error = stk_add(args, intp->intp_name, UIO_SYSSPACE)) != 0) return (error); if (intp->intp_arg != NULL && (error = stk_add(args, intp->intp_arg, UIO_SYSSPACE)) != 0) return (error); if (args->fname != NULL) error = stk_add(args, args->fname, UIO_SYSSPACE); else error = stk_add(args, uap->fname, UIO_USERSPACE); if (error) return (error); /* * Check for an empty argv[]. */ if (stk_getptr(args, argv, &sp)) return (EFAULT); if (sp == NULL) argv_empty = 1; argv += ptrsize; /* ignore original argv[0] */ } if (argv_empty == 0) { /* * Add argv[] strings to the stack. */ for (;;) { if (stk_getptr(args, argv, &sp)) return (EFAULT); if (sp == NULL) break; if ((error = stk_add(args, sp, UIO_USERSPACE)) != 0) return (error); argv += ptrsize; } } argc = (int *)(args->stk_base + args->stk_size) - args->stk_offp; args->arglen = args->stk_strp - args->stk_base; /* * Add environ[] strings to the stack. */ if (envp != NULL) { for (;;) { if (stk_getptr(args, envp, &sp)) return (EFAULT); if (sp == NULL) break; if ((error = stk_add(args, sp, UIO_USERSPACE)) != 0) return (error); envp += ptrsize; } } args->na = (int *)(args->stk_base + args->stk_size) - args->stk_offp; args->ne = args->na - argc; /* * Add AT_SUN_PLATFORM, AT_SUN_EXECNAME, AT_SUN_BRANDNAME, and * AT_SUN_EMULATOR strings to the stack. */ if (auxvpp != NULL && *auxvpp != NULL) { if ((error = stk_add(args, platform, UIO_SYSSPACE)) != 0) return (error); if ((error = stk_add(args, args->pathname, UIO_SYSSPACE)) != 0) return (error); if (args->brandname != NULL && (error = stk_add(args, args->brandname, UIO_SYSSPACE)) != 0) return (error); if (args->emulator != NULL && (error = stk_add(args, args->emulator, UIO_SYSSPACE)) != 0) return (error); } /* * Compute the size of the stack. This includes all the pointers, * the space reserved for the aux vector, and all the strings. * The total number of pointers is args->na (which is argc + envc) * plus 4 more: (1) a pointer's worth of space for argc; (2) the NULL * after the last argument (i.e. argv[argc]); (3) the NULL after the * last environment variable (i.e. envp[envc]); and (4) the NULL after * all the strings, at the very top of the stack. */ size = (args->na + 4) * args->to_ptrsize + args->auxsize + (args->stk_strp - args->stk_base); /* * Pad the string section with zeroes to align the stack size. */ pad = P2NPHASE(size, args->stk_align); if (STK_AVAIL(args) < pad) return (E2BIG); args->usrstack_size = size + pad; while (pad-- != 0) *args->stk_strp++ = 0; args->nc = args->stk_strp - args->stk_base; return (0); } static int stk_copyout(uarg_t *args, char *usrstack, void **auxvpp, user_t *up) { size_t ptrsize = args->to_ptrsize; ssize_t pslen; char *kstrp = args->stk_base; char *ustrp = usrstack - args->nc - ptrsize; char *usp = usrstack - args->usrstack_size; int *offp = (int *)(args->stk_base + args->stk_size); int envc = args->ne; int argc = args->na - envc; int i; /* * Record argc for /proc. */ up->u_argc = argc; /* * Put argc on the stack. Note that even though it's an int, * it always consumes ptrsize bytes (for alignment). */ if (stk_putptr(args, usp, (char *)(uintptr_t)argc)) return (-1); /* * Add argc space (ptrsize) to usp and record argv for /proc. */ up->u_argv = (uintptr_t)(usp += ptrsize); /* * Put the argv[] pointers on the stack. */ for (i = 0; i < argc; i++, usp += ptrsize) if (stk_putptr(args, usp, &ustrp[*--offp])) return (-1); /* * Copy arguments to u_psargs. */ pslen = MIN(args->arglen, PSARGSZ) - 1; for (i = 0; i < pslen; i++) up->u_psargs[i] = (kstrp[i] == '\0' ? ' ' : kstrp[i]); while (i < PSARGSZ) up->u_psargs[i++] = '\0'; /* * Add space for argv[]'s NULL terminator (ptrsize) to usp and * record envp for /proc. */ up->u_envp = (uintptr_t)(usp += ptrsize); /* * Put the envp[] pointers on the stack. */ for (i = 0; i < envc; i++, usp += ptrsize) if (stk_putptr(args, usp, &ustrp[*--offp])) return (-1); /* * Add space for envp[]'s NULL terminator (ptrsize) to usp and * remember where the stack ends, which is also where auxv begins. */ args->stackend = usp += ptrsize; /* * Put all the argv[], envp[], and auxv strings on the stack. */ if (copyout(args->stk_base, ustrp, args->nc)) return (-1); /* * Fill in the aux vector now that we know the user stack addresses * for the AT_SUN_PLATFORM, AT_SUN_EXECNAME, AT_SUN_BRANDNAME and * AT_SUN_EMULATOR strings. */ if (auxvpp != NULL && *auxvpp != NULL) { if (args->to_model == DATAMODEL_NATIVE) { auxv_t **a = (auxv_t **)auxvpp; ADDAUX(*a, AT_SUN_PLATFORM, (long)&ustrp[*--offp]) ADDAUX(*a, AT_SUN_EXECNAME, (long)&ustrp[*--offp]) if (args->brandname != NULL) ADDAUX(*a, AT_SUN_BRANDNAME, (long)&ustrp[*--offp]) if (args->emulator != NULL) ADDAUX(*a, AT_SUN_EMULATOR, (long)&ustrp[*--offp]) } else { auxv32_t **a = (auxv32_t **)auxvpp; ADDAUX(*a, AT_SUN_PLATFORM, (int)(uintptr_t)&ustrp[*--offp]) ADDAUX(*a, AT_SUN_EXECNAME, (int)(uintptr_t)&ustrp[*--offp]) if (args->brandname != NULL) ADDAUX(*a, AT_SUN_BRANDNAME, (int)(uintptr_t)&ustrp[*--offp]) if (args->emulator != NULL) ADDAUX(*a, AT_SUN_EMULATOR, (int)(uintptr_t)&ustrp[*--offp]) } } return (0); } /* * Initialize a new user stack with the specified arguments and environment. * The initial user stack layout is as follows: * * User Stack * +---------------+ <--- curproc->p_usrstack * | | * | slew | * | | * +---------------+ * | NULL | * +---------------+ * | | * | auxv strings | * | | * +---------------+ * | | * | envp strings | * | | * +---------------+ * | | * | argv strings | * | | * +---------------+ <--- ustrp * | | * | aux vector | * | | * +---------------+ <--- auxv * | NULL | * +---------------+ * | envp[envc-1] | * +---------------+ * | ... | * +---------------+ * | envp[0] | * +---------------+ <--- envp[] * | NULL | * +---------------+ * | argv[argc-1] | * +---------------+ * | ... | * +---------------+ * | argv[0] | * +---------------+ <--- argv[] * | argc | * +---------------+ <--- stack base */ int exec_args(execa_t *uap, uarg_t *args, intpdata_t *intp, void **auxvpp) { size_t size; int error; proc_t *p = ttoproc(curthread); user_t *up = PTOU(p); char *usrstack; rctl_entity_p_t e; struct as *as; extern int use_stk_lpg; size_t sp_slew; args->from_model = p->p_model; if (p->p_model == DATAMODEL_NATIVE) { args->from_ptrsize = sizeof (long); } else { args->from_ptrsize = sizeof (int32_t); } if (args->to_model == DATAMODEL_NATIVE) { args->to_ptrsize = sizeof (long); args->ncargs = NCARGS; args->stk_align = STACK_ALIGN; usrstack = (char *)USRSTACK; } else { args->to_ptrsize = sizeof (int32_t); args->ncargs = NCARGS32; args->stk_align = STACK_ALIGN32; usrstack = (char *)USRSTACK32; } ASSERT(P2PHASE((uintptr_t)usrstack, args->stk_align) == 0); #if defined(__sparc) /* * Make sure user register windows are empty before * attempting to make a new stack. */ (void) flush_user_windows_to_stack(NULL); #endif for (size = PAGESIZE; ; size *= 2) { args->stk_size = size; args->stk_base = kmem_alloc(size, KM_SLEEP); args->stk_strp = args->stk_base; args->stk_offp = (int *)(args->stk_base + size); error = stk_copyin(uap, args, intp, auxvpp); if (error == 0) break; kmem_free(args->stk_base, size); if (error != E2BIG && error != ENAMETOOLONG) return (error); if (size >= args->ncargs) return (E2BIG); } size = args->usrstack_size; ASSERT(error == 0); ASSERT(P2PHASE(size, args->stk_align) == 0); ASSERT((ssize_t)STK_AVAIL(args) >= 0); if (size > args->ncargs) { kmem_free(args->stk_base, args->stk_size); return (E2BIG); } /* * Leave only the current lwp and force the other lwps to exit. * If another lwp beat us to the punch by calling exit(), bail out. */ if ((error = exitlwps(0)) != 0) { kmem_free(args->stk_base, args->stk_size); return (error); } /* * Revoke any doors created by the process. */ if (p->p_door_list) door_exit(); /* * Release schedctl data structures. */ if (p->p_pagep) schedctl_proc_cleanup(); /* * Clean up any DTrace helpers for the process. */ if (p->p_dtrace_helpers != NULL) { ASSERT(dtrace_helpers_cleanup != NULL); (*dtrace_helpers_cleanup)(); } mutex_enter(&p->p_lock); /* * Cleanup the DTrace provider associated with this process. */ if (p->p_dtrace_probes) { ASSERT(dtrace_fasttrap_exec_ptr != NULL); dtrace_fasttrap_exec_ptr(p); } mutex_exit(&p->p_lock); /* * discard the lwpchan cache. */ if (p->p_lcp != NULL) lwpchan_destroy_cache(1); /* * Delete the POSIX timers. */ if (p->p_itimer != NULL) timer_exit(); #ifdef C2_AUDIT if (audit_active) audit_exec(args->stk_base, args->stk_base + args->arglen, args->na - args->ne, args->ne); #endif /* * Ensure that we don't change resource associations while we * change address spaces. */ mutex_enter(&p->p_lock); pool_barrier_enter(); mutex_exit(&p->p_lock); /* * Destroy the old address space and create a new one. * From here on, any errors are fatal to the exec()ing process. * On error we return -1, which means the caller must SIGKILL * the process. */ relvm(); mutex_enter(&p->p_lock); pool_barrier_exit(); mutex_exit(&p->p_lock); up->u_execsw = args->execswp; p->p_brkbase = NULL; p->p_brksize = 0; p->p_brkpageszc = 0; p->p_stksize = 0; p->p_stkpageszc = 0; p->p_model = args->to_model; p->p_usrstack = usrstack; p->p_stkprot = args->stk_prot; p->p_datprot = args->dat_prot; /* * Reset resource controls such that all controls are again active as * well as appropriate to the potentially new address model for the * process. */ e.rcep_p.proc = p; e.rcep_t = RCENTITY_PROCESS; rctl_set_reset(p->p_rctls, p, &e); /* Too early to call map_pgsz for the heap */ if (use_stk_lpg) { p->p_stkpageszc = page_szc(map_pgsz(MAPPGSZ_STK, p, 0, 0, 0)); } mutex_enter(&p->p_lock); p->p_flag |= SAUTOLPG; /* kernel controls page sizes */ mutex_exit(&p->p_lock); /* * Some platforms may choose to randomize real stack start by adding a * small slew (not more than a few hundred bytes) to the top of the * stack. This helps avoid cache thrashing when identical processes * simultaneously share caches that don't provide enough associativity * (e.g. sun4v systems). In this case stack slewing makes the same hot * stack variables in different processes to live in different cache * sets increasing effective associativity. */ sp_slew = exec_get_spslew(); ASSERT(P2PHASE(sp_slew, args->stk_align) == 0); exec_set_sp(size + sp_slew); as = as_alloc(); p->p_as = as; as->a_proc = p; if (p->p_model == DATAMODEL_ILP32) as->a_userlimit = (caddr_t)USERLIMIT32; (void) hat_setup(as->a_hat, HAT_ALLOC); /* * Finally, write out the contents of the new stack. */ error = stk_copyout(args, usrstack - sp_slew, auxvpp, up); kmem_free(args->stk_base, args->stk_size); return (error); }