HardenedBSD/sys/kern/imgact_gzip.c

/*
 * Parts of this file are not covered by:
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 *
 * $Id: imgact_gzip.c,v 1.7 1994/10/07 22:26:51 csgr Exp $
 *
 * This module handles execution of a.out files which have been run through
 * "gzip -9".
 *
 * For now you need to use exactly this command to compress the binaries:
 *
 *		gzip -9 -v < /bin/sh > /tmp/sh
 *
 * TODO:
 *	text-segments should be made R/O after being filled
 *	is the vm-stuff safe ?
 * 	should handle the entire header of gzip'ed stuff.
 *	inflate isn't quite reentrant yet...
 *	error-handling is a mess...
 *	so is the rest...
 *	tidy up unnecesary includes
 */


#include <sys/param.h>	/* some header file needs this first foo! */

#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_aout.h>
#include <sys/inflate.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/resourcevar.h>
#include <sys/sysent.h>
#include <sys/systm.h>

#include <vm/vm.h>
#include <vm/vm_kern.h>

extern struct sysentvec aout_sysvec;

int
exec_gzip_imgact(iparams)
	struct image_params *iparams;
{
	int error,error2=0;
	u_char *p = (u_char *) iparams->image_header;
	struct gzip *gz;
	struct gz_global gz_glbl;

	/* If these four are not OK, it isn't a gzip file */
	if (p[0] != 0x1f)   return -1;      /* 0    Simply magic	*/
	if (p[1] != 0x8b)   return -1;      /* 1    Simply magic	*/
	if (p[2] != 0x08)   return -1;      /* 2    Compression method	*/
	if (p[9] != 0x03)   return -1;      /* 9    OS compressed on	*/

	/* If this one contains anything but a comment or a filename
	 * marker, we don't want to chew on it
	 */
	if (p[3] & ~(0x18)) return ENOEXEC; /* 3    Flags		*/

	/* These are of no use to us */
					    /* 4-7  Timestamp		*/
					    /* 8    Extra flags		*/

	gz = malloc(sizeof *gz,M_GZIP,M_NOWAIT);
	if (!gz)
		return ENOMEM;
	bzero(gz,sizeof *gz); /* waste of time ? */

	gz->gz_slide = malloc(WSIZE,M_TEMP,M_NOWAIT);
	if (!gz->gz_slide) {
		free(gz,M_GZIP);
		return ENOMEM;
	}

	gz->ip = iparams;
	gz->error = ENOEXEC;
	gz->idx = 10; 

	if (p[3] & 0x08) {  /* skip a filename */
	    while (p[gz->idx++]) 
		if (gz->idx >= PAGE_SIZE)
		    goto done;
	}

	if (p[3] & 0x10) {  /* skip a comment */
	    while (p[gz->idx++]) 
		if (gz->idx >= PAGE_SIZE)
		    goto done;
	}
	
	gz->len = gz->ip->attr->va_size;

	gz->error = 0;

	error = inflate(gz, &gz_glbl);

	if (gz->inbuf) {
	    error2 = 
		vm_deallocate(kernel_map, (vm_offset_t)gz->inbuf, PAGE_SIZE);
	}

	if (gz->error || error || error2) {
	    printf("Output=%lu ",gz->output);
	    printf("Inflate_error=%d gz->error=%d error2=%d where=%d\n",
		error,gz->error,error2,gz->where);
	    if (gz->error)  
		goto done;
	    if (error) {
		gz->error = ENOEXEC;
		goto done;
	    }
	    if (error2) {
		gz->error = error2;
		goto done;
	    }
	}

    done:
	error = gz->error;
	free(gz->gz_slide,M_TEMP);
	free(gz,M_GZIP);
	return error;
}

int
do_aout_hdr(struct gzip *gz)
{
    int error;
    struct vmspace *vmspace = gz->ip->proc->p_vmspace;
    u_long vmaddr;

    /*
     * Set file/virtual offset based on a.out variant.
     *	We do two cases: host byte order and network byte order
     *	(for NetBSD compatibility)
     */
    switch ((int)(gz->a_out.a_magic & 0xffff)) {
    case ZMAGIC:
	gz->virtual_offset = 0;
	if (gz->a_out.a_text) {
	    gz->file_offset = NBPG;
	} else {
	    /* Bill's "screwball mode" */
	    gz->file_offset = 0;
	}
	break;
    case QMAGIC:
	gz->virtual_offset = NBPG;
	gz->file_offset = 0;
	break;
    default:
	/* NetBSD compatibility */
	switch ((int)(ntohl(gz->a_out.a_magic) & 0xffff)) {
	case ZMAGIC:
	case QMAGIC:
	    gz->virtual_offset = NBPG;
	    gz->file_offset = 0;
	    break;
	default:
	    gz->where = __LINE__;
	    return (-1);
	}
    }

    gz->bss_size = roundup(gz->a_out.a_bss, NBPG);

    /*
     * Check various fields in header for validity/bounds.
     */
    if (/* entry point must lay with text region */
	gz->a_out.a_entry < gz->virtual_offset ||
	gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||

	/* text and data size must each be page rounded */
	gz->a_out.a_text % NBPG ||
	gz->a_out.a_data % NBPG) {
	    gz->where = __LINE__;
	    return (-1);
    }

    /*
     * text/data/bss must not exceed limits
     */
    if (/* text can't exceed maximum text size */
	gz->a_out.a_text > MAXTSIZ ||

	/* data + bss can't exceed maximum data size */
	gz->a_out.a_data + gz->bss_size > MAXDSIZ ||

	/* data + bss can't exceed rlimit */
	gz->a_out.a_data + gz->bss_size >
	    gz->ip->proc->p_rlimit[RLIMIT_DATA].rlim_cur) {
		    gz->where = __LINE__;
		    return (ENOMEM);
    }

    /* Find out how far we should go */
    gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;

    /* copy in arguments and/or environment from old process */
    error = exec_extract_strings(gz->ip);
    if (error) {
	gz->where = __LINE__;
	return (error);
    }

    /*
     * Destroy old process VM and create a new one (with a new stack)
     */
    exec_new_vmspace(gz->ip);

    vmaddr = gz->virtual_offset;

    error = vm_mmap(&vmspace->vm_map,           /* map */
	&vmaddr,                                /* address */
	gz->a_out.a_text,                      /* size */
	VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_WRITE,  /* protection */
	VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_WRITE,
	MAP_ANON | MAP_FIXED,                /* flags */
	0,				        /* vnode */
	0);                                     /* offset */

    if (error) {
	gz->where = __LINE__;
	return (error);
    }

    vmaddr = gz->virtual_offset + gz->a_out.a_text;

    /*
     * Map data read/write (if text is 0, assume text is in data area
     *      [Bill's screwball mode])
     */

    error = vm_mmap(&vmspace->vm_map,
	&vmaddr,
	gz->a_out.a_data,
	VM_PROT_READ | VM_PROT_WRITE | (gz->a_out.a_text ? 0 : VM_PROT_EXECUTE),   
	VM_PROT_ALL, MAP_ANON | MAP_FIXED,
	0,
	0);

    if (error) {
	gz->where = __LINE__;
	return (error);
    }

    /*
     * Allocate demand-zeroed area for uninitialized data
     * "bss" = 'block started by symbol' - named after the IBM 7090
     *      instruction of the same name.
     */
    vmaddr = gz->virtual_offset + gz->a_out.a_text + gz->a_out.a_data;
    error = vm_allocate(&vmspace->vm_map, &vmaddr, gz->bss_size, FALSE);
    if (error) {
	gz->where = __LINE__;
	return (error);
    }

    /* Fill in process VM information */
    vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
    vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
    vmspace->vm_taddr = (caddr_t) gz->virtual_offset;
    vmspace->vm_daddr = (caddr_t) gz->virtual_offset + gz->a_out.a_text;

    /* Fill in image_params */
    gz->ip->interpreted = 0;
    gz->ip->entry_addr = gz->a_out.a_entry;

    gz->ip->proc->p_sysent = &aout_sysvec;

    return 0;
}

/*
 * Tell kern_execve.c about it, with a little help from the linker.
 * Since `const' objects end up in the text segment, TEXT_SET is the
 * correct directive to use.
 */
static const struct execsw gzip_execsw = { exec_gzip_imgact, "gzip" };
TEXT_SET(execsw_set, gzip_execsw);