xref: /src/sys/kern/exec_aout.c

/*	$NetBSD: exec_aout.c,v 1.41.32.1 2025/08/02 05:57:40 perseant Exp $	*/

/*
 * Copyright (c) 1993, 1994 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Christopher G. Demetriou.
 * 4. 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(0, "$NetBSD: exec_aout.c,v 1.41.32.1 2025/08/02 05:57:40 perseant Exp $");

#include <sys/param.h>
#include <sys/types.h>

#include <sys/exec.h>
#include <sys/exec_aout.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sdt.h>
#include <sys/systm.h>
#include <sys/vnode.h>

#include <uvm/uvm_extern.h>

MODULE(MODULE_CLASS_EXEC, exec_aout, NULL);

static struct execsw exec_aout_execsw = {
	.es_hdrsz = sizeof(struct exec),
	.es_makecmds = exec_aout_makecmds,
	.u = {
		.elf_probe_func = NULL,
	},
	.es_emul = &emul_netbsd,
	.es_prio = EXECSW_PRIO_ANY,
	.es_arglen = 0,
	.es_copyargs = copyargs,
	.es_setregs = NULL,
	.es_coredump = coredump_netbsd,
	.es_setup_stack = exec_setup_stack,
};

static int
exec_aout_modcmd(modcmd_t cmd, void *arg)
{

	switch (cmd) {
	case MODULE_CMD_INIT:
		return exec_add(&exec_aout_execsw, 1);

	case MODULE_CMD_FINI:
		return exec_remove(&exec_aout_execsw, 1);

	default:
		return SET_ERROR(ENOTTY);
        }
}

/*
 * exec_aout_makecmds(): Check if it's an a.out-format executable.
 *
 * Given a lwp pointer and an exec package pointer, see if the referent
 * of the epp is in a.out format.  First check 'standard' magic numbers for
 * this architecture.  If that fails, try a CPU-dependent hook.
 *
 * This function, in the former case, or the hook, in the latter, is
 * responsible for creating a set of vmcmds which can be used to build
 * the process's vm space and inserting them into the exec package.
 */

int
exec_aout_makecmds(struct lwp *l, struct exec_package *epp)
{
	u_long midmag, magic;
	u_short mid;
	int error;
	struct exec *execp = epp->ep_hdr;

	if (epp->ep_hdrvalid < sizeof(struct exec))
		return SET_ERROR(ENOEXEC);

	midmag = ntohl(execp->a_midmag);
	mid = (midmag >> 16) & 0x3ff;
	magic = midmag & 0xffff;

	midmag = mid << 16 | magic;

	switch (midmag) {
	case (MID_MACHINE << 16) | ZMAGIC:
		error = exec_aout_prep_zmagic(l, epp);
		break;
	case (MID_MACHINE << 16) | NMAGIC:
		error = exec_aout_prep_nmagic(l, epp);
		break;
	case (MID_MACHINE << 16) | OMAGIC:
		error = exec_aout_prep_omagic(l, epp);
		break;
	default:
		error = cpu_exec_aout_makecmds(l, epp);
	}

	if (error)
		kill_vmcmds(&epp->ep_vmcmds);
	else
		epp->ep_flags &= ~EXEC_TOPDOWN_VM;

	return error;
}

/*
 * exec_aout_prep_zmagic(): Prepare a 'native' ZMAGIC binary's exec package
 *
 * First, set of the various offsets/lengths in the exec package.
 *
 * Then, mark the text image busy (so it can be demand paged) or error
 * out if this is not possible.  Finally, set up vmcmds for the
 * text, data, bss, and stack segments.
 */

int
exec_aout_prep_zmagic(struct lwp *l, struct exec_package *epp)
{
	struct exec *execp = epp->ep_hdr;
	int error;

	epp->ep_taddr = AOUT_LDPGSZ;
	epp->ep_tsize = execp->a_text;
	epp->ep_daddr = epp->ep_taddr + execp->a_text;
	epp->ep_dsize = execp->a_data + execp->a_bss;
	epp->ep_entry = execp->a_entry;

	error = vn_marktext(epp->ep_vp);
	if (error)
		return (error);

	/* set up command for text segment */
	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_pagedvn, round_page(execp->a_text),
	    epp->ep_taddr, epp->ep_vp, 0, VM_PROT_READ|VM_PROT_EXECUTE);

	/* set up command for data segment */
	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_pagedvn, round_page(execp->a_data),
	    epp->ep_daddr, epp->ep_vp, execp->a_text,
	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	/* set up command for bss segment */
	if (execp->a_bss > 0)
		NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, execp->a_bss,
		    epp->ep_daddr + execp->a_data, NULLVP, 0,
		    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	return (*epp->ep_esch->es_setup_stack)(l, epp);
}

/*
 * exec_aout_prep_nmagic(): Prepare a 'native' NMAGIC binary's exec package
 */

int
exec_aout_prep_nmagic(struct lwp *l, struct exec_package *epp)
{
	struct exec *execp = epp->ep_hdr;
	long bsize, baddr;

	epp->ep_taddr = AOUT_LDPGSZ;
	epp->ep_tsize = execp->a_text;
	epp->ep_daddr = roundup(epp->ep_taddr + execp->a_text, AOUT_LDPGSZ);
	epp->ep_dsize = execp->a_data + execp->a_bss;
	epp->ep_entry = execp->a_entry;

	/* set up command for text segment */
	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, execp->a_text,
	    epp->ep_taddr, epp->ep_vp, sizeof(struct exec),
	    VM_PROT_READ|VM_PROT_EXECUTE);

	/* set up command for data segment */
	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, execp->a_data,
	    epp->ep_daddr, epp->ep_vp, execp->a_text + sizeof(struct exec),
	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	/* set up command for bss segment */
	baddr = round_page(epp->ep_daddr + execp->a_data);
	bsize = epp->ep_daddr + epp->ep_dsize - baddr;
	if (bsize > 0)
		NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, bsize, baddr,
		    NULLVP, 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	return (*epp->ep_esch->es_setup_stack)(l, epp);
}

/*
 * exec_aout_prep_omagic(): Prepare a 'native' OMAGIC binary's exec package
 */

int
exec_aout_prep_omagic(struct lwp *l, struct exec_package *epp)
{
	struct exec *execp = epp->ep_hdr;
	long dsize, bsize, baddr;

	epp->ep_taddr = AOUT_LDPGSZ;
	epp->ep_tsize = execp->a_text;
	epp->ep_daddr = epp->ep_taddr + execp->a_text;
	epp->ep_dsize = execp->a_data + execp->a_bss;
	epp->ep_entry = execp->a_entry;

	/* set up command for text and data segments */
	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn,
	    execp->a_text + execp->a_data, epp->ep_taddr, epp->ep_vp,
	    sizeof(struct exec), VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	/* set up command for bss segment */
	baddr = round_page(epp->ep_daddr + execp->a_data);
	bsize = epp->ep_daddr + epp->ep_dsize - baddr;
	if (bsize > 0)
		NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, bsize, baddr,
		    NULLVP, 0, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);

	/*
	 * Make sure (# of pages) mapped above equals (vm_tsize + vm_dsize);
	 * obreak(2) relies on this fact. Both `vm_tsize' and `vm_dsize' are
	 * computed (in execve(2)) by rounding *up* `ep_tsize' and `ep_dsize'
	 * respectively to page boundaries.
	 * Compensate `ep_dsize' for the amount of data covered by the last
	 * text page.
	 */
	dsize = epp->ep_dsize + execp->a_text - round_page(execp->a_text);
	epp->ep_dsize = (dsize > 0) ? dsize : 0;
	return (*epp->ep_esch->es_setup_stack)(l, epp);
}