exec/intp/intp.c

	intp.c revision 9acbbeaf2a1ffe5c14b244867d427714fab43c5c
/*
 * 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.
 */

/*  Copyright (c) 1988 AT&T */
/*    All Rights Reserved   */


#pragma ident   "%Z%%M% %I% %E% SMI" /* from S5R4 1.6 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysmacros.h>
#include <sys/signal.h>
#include <sys/cred.h>
#include <sys/user.h>
#include <sys/errno.h>
#include <sys/vnode.h>
#include <sys/proc.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/pathname.h>
#include <sys/disp.h>
#include <sys/exec.h>
#include <sys/kmem.h>
#include <sys/note.h>

/*
 * This is the loadable module wrapper.
 */
#include <sys/modctl.h>

extern int intpexec();

static struct execsw esw = {
    intpmagicstr,
    0,
    2,
    intpexec,
    NULL
};

/*
 * Module linkage information for the kernel.
 */
extern struct mod_ops mod_execops;

static struct modlexec modlexec = {
    &mod_execops, "exec mod for interp", &esw
};

static struct modlinkage modlinkage = {
    MODREV_1, (void *)&modlexec, NULL
};

int
_init()
{
    return (mod_install(&modlinkage));
}

int
_fini()
{
    return (mod_remove(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}


/*
 * Crack open a '#!' line.
 */
static int
getintphead(struct vnode *vp, struct intpdata *idatap)
{
    int error;
    char *cp, *linep = idatap->intp;
    ssize_t resid;

    /*
     * Read the entire line and confirm that it starts with '#!'.
     */
    if (error = vn_rdwr(UIO_READ, vp, linep, INTPSZ, (offset_t)0,
        UIO_SYSSPACE, 0, (rlim64_t)0, CRED(), &resid))
        return (error);
    if (resid > INTPSZ-2 || linep[0] != '#' || linep[1] != '!')
        return (ENOEXEC);
    /*
     * Blank all white space and find the newline.
     */
    for (cp = &linep[2]; cp < &linep[INTPSZ] && *cp != '\n'; cp++)
        if (*cp == '\t')
            *cp = ' ';
    if (cp >= &linep[INTPSZ])
        return (ENOEXEC);
    ASSERT(*cp == '\n');
    *cp = '\0';

    /*
     * Locate the beginning and end of the interpreter name.
     * In addition to the name, one additional argument may
     * optionally be included here, to be prepended to the
     * arguments provided on the command line.  Thus, for
     * example, you can say
     *
     *  #! /usr/bin/awk -f
     */
    for (cp = &linep[2]; *cp == ' '; cp++)
        ;
    if (*cp == '\0')
        return (ENOEXEC);
    idatap->intp_name = cp;
    while (*cp && *cp != ' ')
        cp++;
    if (*cp == '\0')
        idatap->intp_arg = NULL;
    else {
        *cp++ = '\0';
        while (*cp == ' ')
            cp++;
        if (*cp == '\0')
            idatap->intp_arg = NULL;
        else {
            idatap->intp_arg = cp;
            while (*cp && *cp != ' ')
                cp++;
            *cp = '\0';
        }
    }
    return (0);
}

int
intpexec(
    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,
    int brand_action)
{
    _NOTE(ARGUNUSED(brand_action))
    vnode_t *nvp;
    int error = 0;
    struct intpdata idata;
    struct pathname intppn;
    struct pathname resolvepn;
    char *opath;
    char devfd[14];
    int fd = -1;

    if (level) {        /* Can't recurse */
        error = ENOEXEC;
        goto bad;
    }

    ASSERT(idatap == (struct intpdata *)NULL);

    /*
     * Allocate a buffer to read in the interpreter pathname.
     */
    idata.intp = kmem_alloc(INTPSZ, KM_SLEEP);
    if (error = getintphead(vp, &idata))
        goto fail;

    /*
     * Look the new vnode up.
     */
    if (error = pn_get(idata.intp_name, UIO_SYSSPACE, &intppn))
        goto fail;
    pn_alloc(&resolvepn);
    if (error = lookuppn(&intppn, &resolvepn, FOLLOW, NULLVPP, &nvp)) {
        pn_free(&resolvepn);
        pn_free(&intppn);
        goto fail;
    }
    opath = args->pathname;
    args->pathname = resolvepn.pn_path;
    /* don't free resolvepn until we are done with args */
    pn_free(&intppn);

    /*
     * When we're executing a set-uid script resulting in uids
     * mismatching or when we execute with additional privileges,
     * we close the "replace script between exec and open by shell"
     * hole by passing the script as /dev/fd parameter.
     */
    if ((setid & EXECSETID_PRIVS) != 0 ||
        (setid & (EXECSETID_UGIDS|EXECSETID_SETID)) ==
        (EXECSETID_UGIDS|EXECSETID_SETID)) {
        (void) strcpy(devfd, "/dev/fd/");
        if (error = execopen(&vp, &fd))
            goto done;
        numtos(fd, &devfd[8]);
        args->fname = devfd;
    }

    error = gexec(&nvp, uap, args, &idata, ++level, execsz, exec_file, cred,
        EBA_NONE);
done:
    VN_RELE(nvp);
    args->pathname = opath;
    pn_free(&resolvepn);
fail:
    kmem_free(idata.intp, INTPSZ);
    if (error && fd != -1)
        (void) execclose(fd);
bad:
    return (error);
}