/* $NetBSD: subr_emul.c,v 1.2 2019/01/27 02:08:43 pgoyette Exp $ */

/* $NetBSD: subr_emul.c,v 1.2 2019/01/27 02:08:43 pgoyette Exp $ */

/*-
* Copyright (c) 1994, 2000, 2005, 2015 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Christos Zoulas and Maxime Villard.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* Copyright (c) 1996 Christopher G. Demetriou
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: subr_emul.c,v 1.2 2019/01/27 02:08:43 pgoyette Exp $");

#ifdef _KERNEL_OPT
#include "opt_pax.h"
#endif /* _KERNEL_OPT */

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/namei.h>
#include <sys/exec.h>

#include <compat/common/compat_util.h>

void
emul_find_root(struct lwp *l, struct exec_package *epp)
{
struct vnode *vp;
const char *emul_path;

if (epp->ep_emul_root != NULL)
/* We've already found it */
return;

emul_path = epp->ep_esch->es_emul->e_path;
if (emul_path == NULL)
/* Emulation doesn't have a root */
return;

if (namei_simple_kernel(emul_path, NSM_FOLLOW_NOEMULROOT, &vp) != 0)
/* emulation root doesn't exist */
return;

epp->ep_emul_root = vp;
}

/*
* Search the alternate path for dynamic binary interpreter. If not found
* there, check if the interpreter exists in within 'proper' tree.
*/
int
emul_find_interp(struct lwp *l, struct exec_package *epp, const char *itp)
{
int error;
struct pathbuf *pb;
struct nameidata nd;
unsigned int flags;

pb = pathbuf_create(itp);
if (pb == NULL) {
return ENOMEM;
}

/* If we haven't found the emulation root already, do so now */
/* Maybe we should remember failures somehow ? */
if (epp->ep_esch->es_emul->e_path != 0 && epp->ep_emul_root == NULL)
emul_find_root(l, epp);

if (epp->ep_interp != NULL)
vrele(epp->ep_interp);

/* We need to use the emulation root for the new program,
* not the one for the current process. */
if (epp->ep_emul_root == NULL)
flags = FOLLOW;
else {
nd.ni_erootdir = epp->ep_emul_root;
/* hack: Pass in the emulation path for ktrace calls */
nd.ni_next = epp->ep_esch->es_emul->e_path;
flags = FOLLOW | TRYEMULROOT | EMULROOTSET;
}

NDINIT(&nd, LOOKUP, flags, pb);
error = namei(&nd);
if (error != 0) {
epp->ep_interp = NULL;
pathbuf_destroy(pb);
return error;
}

/* Save interpreter in case we actually need to load it */
epp->ep_interp = nd.ni_vp;

pathbuf_destroy(pb);

return 0;
}