e3669c3393
count is 0, wait for use count to drain before finishing the close. This is necessary in order for multiple processes to safely share file descriptor tables.
314 lines
9.1 KiB
C
314 lines
9.1 KiB
C
/* $NetBSD: exec_script.c,v 1.21 1999/05/05 20:01:08 thorpej Exp $ */
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/*
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* Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Christopher G. Demetriou.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#if defined(SETUIDSCRIPTS) && !defined(FDSCRIPTS)
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#define FDSCRIPTS /* Need this for safe set-id scripts. */
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#endif
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/malloc.h>
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#include <sys/vnode.h>
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#include <sys/namei.h>
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#include <sys/file.h>
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#ifdef SETUIDSCRIPTS
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#include <sys/stat.h>
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#endif
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#include <sys/filedesc.h>
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#include <sys/exec.h>
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#include <sys/resourcevar.h>
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#include <vm/vm.h>
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#include <sys/exec_script.h>
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/*
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* exec_script_makecmds(): Check if it's an executable shell script.
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*
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* Given a proc pointer and an exec package pointer, see if the referent
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* of the epp is in shell script. If it is, then set thing up so that
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* the script can be run. This involves preparing the address space
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* and arguments for the shell which will run the script.
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*
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* This function is ultimately responsible for creating a set of vmcmds
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* which can be used to build the process's vm space and inserting them
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* into the exec package.
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*/
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int
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exec_script_makecmds(p, epp)
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struct proc *p;
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struct exec_package *epp;
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{
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int error, hdrlinelen, shellnamelen, shellarglen;
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char *hdrstr = epp->ep_hdr;
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char *cp, *shellname, *shellarg, *oldpnbuf;
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char **shellargp, **tmpsap;
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struct vnode *scriptvp;
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#ifdef SETUIDSCRIPTS
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/* Gcc needs those initialized for spurious uninitialized warning */
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uid_t script_uid = (uid_t) -1;
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gid_t script_gid = NOGROUP;
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u_short script_sbits;
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#endif
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/*
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* if the magic isn't that of a shell script, or we've already
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* done shell script processing for this exec, punt on it.
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*/
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if ((epp->ep_flags & EXEC_INDIR) != 0 ||
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epp->ep_hdrvalid < EXEC_SCRIPT_MAGICLEN ||
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strncmp(hdrstr, EXEC_SCRIPT_MAGIC, EXEC_SCRIPT_MAGICLEN))
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return ENOEXEC;
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/*
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* check that the shell spec is terminated by a newline,
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* and that it isn't too large. Don't modify the
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* buffer unless we're ready to commit to handling it.
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* (The latter requirement means that we have to check
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* for both spaces and tabs later on.)
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*/
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hdrlinelen = min(epp->ep_hdrvalid, MAXINTERP);
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for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; cp < hdrstr + hdrlinelen;
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cp++) {
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if (*cp == '\n') {
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*cp = '\0';
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break;
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}
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}
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if (cp >= hdrstr + hdrlinelen)
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return ENOEXEC;
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shellname = NULL;
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shellarg = NULL;
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shellarglen = 0;
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/* strip spaces before the shell name */
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for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t';
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cp++)
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;
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/* collect the shell name; remember it's length for later */
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shellname = cp;
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shellnamelen = 0;
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if (*cp == '\0')
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goto check_shell;
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for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++)
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shellnamelen++;
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if (*cp == '\0')
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goto check_shell;
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*cp++ = '\0';
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/* skip spaces before any argument */
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for ( /* cp = cp */ ; *cp == ' ' || *cp == '\t'; cp++)
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;
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if (*cp == '\0')
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goto check_shell;
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/*
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* collect the shell argument. everything after the shell name
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* is passed as ONE argument; that's the correct (historical)
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* behaviour.
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*/
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shellarg = cp;
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for ( /* cp = cp */ ; *cp != '\0'; cp++)
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shellarglen++;
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*cp++ = '\0';
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check_shell:
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#ifdef SETUIDSCRIPTS
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/*
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* MNT_NOSUID and STRC are already taken care of by check_exec,
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* so we don't need to worry about them now or later.
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*/
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script_sbits = epp->ep_vap->va_mode & (S_ISUID | S_ISGID);
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if (script_sbits != 0) {
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script_uid = epp->ep_vap->va_uid;
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script_gid = epp->ep_vap->va_gid;
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}
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#endif
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#ifdef FDSCRIPTS
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/*
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* if the script isn't readable, or it's set-id, then we've
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* gotta supply a "/dev/fd/..." for the shell to read.
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* Note that stupid shells (csh) do the wrong thing, and
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* close all open fd's when the start. That kills this
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* method of implementing "safe" set-id and x-only scripts.
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*/
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vn_lock(epp->ep_vp, LK_EXCLUSIVE | LK_RETRY);
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error = VOP_ACCESS(epp->ep_vp, VREAD, p->p_ucred, p);
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VOP_UNLOCK(epp->ep_vp, 0);
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if (error == EACCES
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#ifdef SETUIDSCRIPTS
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|| script_sbits
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#endif
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) {
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struct file *fp;
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extern struct fileops vnops;
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#if defined(DIAGNOSTIC) && defined(FDSCRIPTS)
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if (epp->ep_flags & EXEC_HASFD)
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panic("exec_script_makecmds: epp already has a fd");
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#endif
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/* falloc() will use the descriptor for us */
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if ((error = falloc(p, &fp, &epp->ep_fd)) != 0) {
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scriptvp = NULL;
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shellargp = NULL;
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goto fail;
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}
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epp->ep_flags |= EXEC_HASFD;
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fp->f_type = DTYPE_VNODE;
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fp->f_ops = &vnops;
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fp->f_data = (caddr_t) epp->ep_vp;
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fp->f_flag = FREAD;
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FILE_UNUSE(fp);
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}
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#endif
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/* set up the parameters for the recursive check_exec() call */
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epp->ep_ndp->ni_dirp = shellname;
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epp->ep_ndp->ni_segflg = UIO_SYSSPACE;
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epp->ep_flags |= EXEC_INDIR;
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/* and set up the fake args list, for later */
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MALLOC(shellargp, char **, 4 * sizeof(char *), M_EXEC, M_WAITOK);
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tmpsap = shellargp;
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MALLOC(*tmpsap, char *, shellnamelen + 1, M_EXEC, M_WAITOK);
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strcpy(*tmpsap++, shellname);
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if (shellarg != NULL) {
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MALLOC(*tmpsap, char *, shellarglen + 1, M_EXEC, M_WAITOK);
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strcpy(*tmpsap++, shellarg);
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}
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MALLOC(*tmpsap, char *, MAXPATHLEN, M_EXEC, M_WAITOK);
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#ifdef FDSCRIPTS
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if ((epp->ep_flags & EXEC_HASFD) == 0) {
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#endif
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/* normally can't fail, but check for it if diagnostic */
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error = copyinstr(epp->ep_name, *tmpsap++, MAXPATHLEN,
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(size_t *)0);
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#ifdef DIAGNOSTIC
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if (error != 0)
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panic("exec_script: copyinstr couldn't fail\n");
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#endif
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#ifdef FDSCRIPTS
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} else
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sprintf(*tmpsap++, "/dev/fd/%d", epp->ep_fd);
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#endif
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*tmpsap = NULL;
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/*
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* mark the header we have as invalid; check_exec will read
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* the header from the new executable
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*/
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epp->ep_hdrvalid = 0;
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/*
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* remember the old vp and pnbuf for later, so we can restore
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* them if check_exec() fails.
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*/
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scriptvp = epp->ep_vp;
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oldpnbuf = epp->ep_ndp->ni_cnd.cn_pnbuf;
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if ((error = check_exec(p, epp)) == 0) {
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/* note that we've clobbered the header */
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epp->ep_flags |= EXEC_DESTR;
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/*
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* It succeeded. Unlock the script and
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* close it if we aren't using it any more.
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* Also, set things up so that the fake args
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* list will be used.
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*/
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if ((epp->ep_flags & EXEC_HASFD) == 0) {
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vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
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VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
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vput(scriptvp);
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}
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/* free the old pathname buffer */
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FREE(oldpnbuf, M_NAMEI);
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epp->ep_flags |= (EXEC_HASARGL | EXEC_SKIPARG);
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epp->ep_fa = shellargp;
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#ifdef SETUIDSCRIPTS
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/*
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* set thing up so that set-id scripts will be
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* handled appropriately
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*/
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epp->ep_vap->va_mode |= script_sbits;
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if (script_sbits & S_ISUID)
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epp->ep_vap->va_uid = script_uid;
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if (script_sbits & S_ISGID)
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epp->ep_vap->va_gid = script_gid;
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#endif
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return (0);
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}
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/* XXX oldpnbuf not set for "goto fail" path */
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epp->ep_ndp->ni_cnd.cn_pnbuf = oldpnbuf;
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#ifdef FDSCRIPTS
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fail:
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#endif
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/* note that we've clobbered the header */
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epp->ep_flags |= EXEC_DESTR;
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/* kill the opened file descriptor, else close the file */
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if (epp->ep_flags & EXEC_HASFD) {
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epp->ep_flags &= ~EXEC_HASFD;
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(void) fdrelease(p, epp->ep_fd);
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} else if (scriptvp) {
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vn_lock(scriptvp, LK_EXCLUSIVE | LK_RETRY);
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VOP_CLOSE(scriptvp, FREAD, p->p_ucred, p);
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vput(scriptvp);
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}
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FREE(epp->ep_ndp->ni_cnd.cn_pnbuf, M_NAMEI);
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/* free the fake arg list, because we're not returning it */
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if ((tmpsap = shellargp) != NULL) {
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while (*tmpsap != NULL) {
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FREE(*tmpsap, M_EXEC);
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tmpsap++;
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}
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FREE(shellargp, M_EXEC);
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}
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/*
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* free any vmspace-creation commands,
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* and release their references
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*/
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kill_vmcmds(&epp->ep_vmcmds);
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return error;
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}
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