imgact_linux.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1994-1996 Søren Schmidt
 * All rights reserved.
 *
 * Based heavily on /sys/kern/imgact_aout.c which is:
 * Copyright (c) 1993, David Greenman
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_aout.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/vnode.h>

#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>

#include <i386/linux/linux.h>

static int	exec_linux_imgact(struct image_params *iparams);

static int
exec_linux_imgact(struct image_params *imgp)
{
	const struct exec *a_out = (const struct exec *) imgp->image_header;
	struct vmspace *vmspace;
	vm_offset_t vmaddr;
	unsigned long virtual_offset, file_offset;
	unsigned long bss_size;
	ssize_t aresid;
	int error;

	if (((a_out->a_magic >> 16) & 0xff) != 0x64)
		return (-1);

	/*
	 * Set file/virtual offset based on a.out variant.
	 */
	switch ((int)(a_out->a_magic & 0xffff)) {
	case 0413:
		virtual_offset = 0;
		file_offset = 1024;
		break;
	case 0314:
		virtual_offset = 4096;
		file_offset = 0;
		break;
	default:
		return (-1);
	}
	bss_size = round_page(a_out->a_bss);
#ifdef DEBUG
	printf("imgact: text: %08lx, data: %08lx, bss: %08lx\n",
	    (u_long)a_out->a_text, (u_long)a_out->a_data, bss_size);
#endif

	/*
	 * Check various fields in header for validity/bounds.
	 */
	if (a_out->a_entry < virtual_offset ||
	    a_out->a_entry >= virtual_offset + a_out->a_text ||
	    a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK)
		return (-1);

	/* text + data can't exceed file size */
	if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
		return (EFAULT);
	/*
	 * text/data/bss must not exceed limits
	 */
	PROC_LOCK(imgp->proc);
	if (a_out->a_text > maxtsiz ||
	    a_out->a_data + bss_size > lim_cur_proc(imgp->proc, RLIMIT_DATA) ||
	    racct_set(imgp->proc, RACCT_DATA, a_out->a_data + bss_size) != 0) {
		PROC_UNLOCK(imgp->proc);
		return (ENOMEM);
	}
	PROC_UNLOCK(imgp->proc);

	VOP_UNLOCK(imgp->vp);

	/*
	 * Destroy old process VM and create a new one (with a new stack)
	 */
	error = exec_new_vmspace(imgp, &linux_sysvec);
	if (error)
		goto fail;
	vmspace = imgp->proc->p_vmspace;

	/*
	 * Check if file_offset page aligned,.
	 * Currently we cannot handle misaligned file offsets,
	 * and so we read in the entire image (what a waste).
	 */
	if (file_offset & PAGE_MASK) {
#ifdef DEBUG
		printf("imgact: Non page aligned binary %lu\n", file_offset);
#endif
		/*
		 * Map text+data+bss read/write/execute
		 */
		vmaddr = virtual_offset;
		error = vm_map_find(&vmspace->vm_map, NULL, 0, &vmaddr,
		    a_out->a_text + a_out->a_data + bss_size, 0, VMFS_NO_SPACE,
		    VM_PROT_ALL, VM_PROT_ALL, 0);
		if (error)
			goto fail;

		error = vn_rdwr(UIO_READ, imgp->vp, (void *)vmaddr, file_offset,
		    a_out->a_text + a_out->a_data, UIO_USERSPACE, 0,
		    curthread->td_ucred, NOCRED, &aresid, curthread);
		if (error != 0)
			goto fail;
		if (aresid != 0) {
			error = ENOEXEC;
			goto fail;
		}

		/*
		 * remove write enable on the 'text' part
		 */
		error = vm_map_protect(&vmspace->vm_map, vmaddr,
		    vmaddr + a_out->a_text, 0, VM_PROT_EXECUTE | VM_PROT_READ,
		    VM_MAP_PROTECT_SET_MAXPROT);
		if (error)
			goto fail;
	} else {
#ifdef DEBUG
		printf("imgact: Page aligned binary %lu\n", file_offset);
#endif
		/*
		 * Map text+data read/execute
		 */
		vmaddr = virtual_offset;
		error = vm_mmap(&vmspace->vm_map, &vmaddr,
		    a_out->a_text + a_out->a_data,
		    VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
		    MAP_PRIVATE | MAP_FIXED, OBJT_VNODE, imgp->vp, file_offset);
		if (error)
			goto fail;

#ifdef DEBUG
		printf("imgact: startaddr=%08lx, length=%08lx\n",
		    (u_long)vmaddr,
		    (u_long)a_out->a_text + (u_long)a_out->a_data);
#endif
		/*
		 * allow read/write of data
		 */
		error = vm_map_protect(&vmspace->vm_map, vmaddr + a_out->a_text,
		    vmaddr + a_out->a_text + a_out->a_data, VM_PROT_ALL, 0,
		    VM_MAP_PROTECT_SET_PROT);
		if (error)
			goto fail;

		/*
		 * Allocate anon demand-zeroed area for uninitialized data
		 */
		if (bss_size != 0) {
			vmaddr = virtual_offset + a_out->a_text + a_out->a_data;
		error = vm_map_find(&vmspace->vm_map, NULL, 0, &vmaddr,
		    bss_size, 0, VMFS_NO_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0);
		if (error)
			goto fail;
#ifdef DEBUG
		printf("imgact: bssaddr=%08lx, length=%08lx\n", (u_long)vmaddr,
		    bss_size);
#endif
		}
	}
	/* Fill in process VM information */
	vmspace->vm_tsize = round_page(a_out->a_text) >> PAGE_SHIFT;
	vmspace->vm_dsize = round_page(a_out->a_data + bss_size) >> PAGE_SHIFT;
	vmspace->vm_taddr = (caddr_t)(void *)(uintptr_t)virtual_offset;
	vmspace->vm_daddr =
	    (caddr_t)(void *)(uintptr_t)(virtual_offset + a_out->a_text);

	error = exec_map_stack(imgp);
	if (error != 0)
		goto fail;

	/* Fill in image_params */
	imgp->interpreted = 0;
	imgp->entry_addr = a_out->a_entry;

	imgp->proc->p_sysent = &linux_sysvec;

fail:
	vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
	return (error);
}

/*
 * Tell kern_execve.c about it, with a little help from the linker.
 */
static struct execsw linux_execsw = { exec_linux_imgact, "Linux a.out" };
EXEC_SET(linuxaout, linux_execsw);