The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/imgact_gzip.c

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    1 /*
    2  * ----------------------------------------------------------------------------
    3  * "THE BEER-WARE LICENSE" (Revision 42):
    4  * <phk@login.dkuug.dk> wrote this file.  As long as you retain this notice you
    5  * can do whatever you want with this stuff. If we meet some day, and you think
    6  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
    7  * ----------------------------------------------------------------------------
    8  *
    9  * $FreeBSD$
   10  *
   11  * This module handles execution of a.out files which have been run through
   12  * "gzip".  This saves diskspace, but wastes cpu-cycles and VM.
   13  *
   14  * TODO:
   15  *      text-segments should be made R/O after being filled
   16  *      is the vm-stuff safe ?
   17  *      should handle the entire header of gzip'ed stuff.
   18  *      inflate isn't quite reentrant yet...
   19  *      error-handling is a mess...
   20  *      so is the rest...
   21  *      tidy up unnecesary includes
   22  */
   23 
   24 #include <sys/param.h>
   25 #include <sys/exec.h>
   26 #include <sys/imgact.h>
   27 #include <sys/imgact_aout.h>
   28 #include <sys/kernel.h>
   29 #include <sys/mman.h>
   30 #include <sys/proc.h>
   31 #include <sys/resourcevar.h>
   32 #include <sys/sysent.h>
   33 #include <sys/systm.h>
   34 #include <sys/vnode.h>
   35 #include <sys/inflate.h>
   36 
   37 #include <vm/vm.h>
   38 #include <vm/vm_param.h>
   39 #include <vm/vm_prot.h>
   40 #include <sys/lock.h>
   41 #include <vm/pmap.h>
   42 #include <vm/vm_map.h>
   43 #include <vm/vm_kern.h>
   44 #include <vm/vm_extern.h>
   45 
   46 struct imgact_gzip {
   47         struct image_params *ip;
   48         struct exec     a_out;
   49         int             error;
   50         int             gotheader;
   51         int             where;
   52         u_char         *inbuf;
   53         u_long          offset;
   54         u_long          output;
   55         u_long          len;
   56         int             idx;
   57         u_long          virtual_offset, file_offset, file_end, bss_size;
   58 };
   59 
   60 static int exec_gzip_imgact __P((struct image_params *imgp));
   61 static int NextByte __P((void *vp));
   62 static int do_aout_hdr __P((struct imgact_gzip *));
   63 static int Flush __P((void *vp, u_char *, u_long siz));
   64 
   65 static int
   66 exec_gzip_imgact(imgp)
   67         struct image_params *imgp;
   68 {
   69         int             error, error2 = 0;
   70         const u_char   *p = (const u_char *) imgp->image_header;
   71         struct imgact_gzip igz;
   72         struct inflate  infl;
   73         struct vmspace *vmspace;
   74 
   75         /* If these four are not OK, it isn't a gzip file */
   76         if (p[0] != 0x1f)
   77                 return -1;      /* 0    Simply magic     */
   78         if (p[1] != 0x8b)
   79                 return -1;      /* 1    Simply magic     */
   80         if (p[2] != 0x08)
   81                 return -1;      /* 2    Compression method       */
   82         if (p[9] != 0x03)
   83                 return -1;      /* 9    OS compressed on         */
   84 
   85         /*
   86          * If this one contains anything but a comment or a filename marker,
   87          * we don't want to chew on it
   88          */
   89         if (p[3] & ~(0x18))
   90                 return ENOEXEC; /* 3    Flags            */
   91 
   92         /* These are of no use to us */
   93         /* 4-7  Timestamp                */
   94         /* 8    Extra flags              */
   95 
   96         bzero(&igz, sizeof igz);
   97         bzero(&infl, sizeof infl);
   98         infl.gz_private = (void *) &igz;
   99         infl.gz_input = NextByte;
  100         infl.gz_output = Flush;
  101 
  102         igz.ip = imgp;
  103         igz.idx = 10;
  104 
  105         if (p[3] & 0x08) {      /* skip a filename */
  106                 while (p[igz.idx++])
  107                         if (igz.idx >= PAGE_SIZE)
  108                                 return ENOEXEC;
  109         }
  110         if (p[3] & 0x10) {      /* skip a comment */
  111                 while (p[igz.idx++])
  112                         if (igz.idx >= PAGE_SIZE)
  113                                 return ENOEXEC;
  114         }
  115         igz.len = imgp->attr->va_size;
  116 
  117         error = inflate(&infl);
  118 
  119         /*
  120          * The unzipped file may not even have been long enough to contain
  121          * a header giving Flush() a chance to return error.  Check for this.
  122          */
  123         if (!igz.gotheader)
  124                 return ENOEXEC;
  125 
  126         if ( !error ) {
  127                 vmspace = imgp->proc->p_vmspace;
  128                 error = vm_map_protect(&vmspace->vm_map,
  129                         (vm_offset_t) vmspace->vm_taddr,
  130                         (vm_offset_t) (vmspace->vm_taddr + 
  131                                       (vmspace->vm_tsize << PAGE_SHIFT)) ,
  132                         VM_PROT_READ|VM_PROT_EXECUTE,0);
  133         }
  134 
  135         if (igz.inbuf) {
  136                 error2 =
  137                         vm_map_remove(kernel_map, (vm_offset_t) igz.inbuf,
  138                             (vm_offset_t) igz.inbuf + PAGE_SIZE);
  139         }
  140         if (igz.error || error || error2) {
  141                 printf("Output=%lu ", igz.output);
  142                 printf("Inflate_error=%d igz.error=%d error2=%d where=%d\n",
  143                        error, igz.error, error2, igz.where);
  144         }
  145         if (igz.error)
  146                 return igz.error;
  147         if (error)
  148                 return ENOEXEC;
  149         if (error2)
  150                 return error2;
  151         return 0;
  152 }
  153 
  154 static int
  155 do_aout_hdr(struct imgact_gzip * gz)
  156 {
  157         int             error;
  158         struct vmspace *vmspace;
  159         vm_offset_t     vmaddr;
  160 
  161         /*
  162          * Set file/virtual offset based on a.out variant. We do two cases:
  163          * host byte order and network byte order (for NetBSD compatibility)
  164          */
  165         switch ((int) (gz->a_out.a_magic & 0xffff)) {
  166         case ZMAGIC:
  167                 gz->virtual_offset = 0;
  168                 if (gz->a_out.a_text) {
  169                         gz->file_offset = PAGE_SIZE;
  170                 } else {
  171                         /* Bill's "screwball mode" */
  172                         gz->file_offset = 0;
  173                 }
  174                 break;
  175         case QMAGIC:
  176                 gz->virtual_offset = PAGE_SIZE;
  177                 gz->file_offset = 0;
  178                 break;
  179         default:
  180                 /* NetBSD compatibility */
  181                 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) {
  182                 case ZMAGIC:
  183                 case QMAGIC:
  184                         gz->virtual_offset = PAGE_SIZE;
  185                         gz->file_offset = 0;
  186                         break;
  187                 default:
  188                         gz->where = __LINE__;
  189                         return (-1);
  190                 }
  191         }
  192 
  193         gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE);
  194 
  195         /*
  196          * Check various fields in header for validity/bounds.
  197          */
  198         if (                    /* entry point must lay with text region */
  199             gz->a_out.a_entry < gz->virtual_offset ||
  200             gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||
  201 
  202         /* text and data size must each be page rounded */
  203             gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) {
  204                 gz->where = __LINE__;
  205                 return (-1);
  206         }
  207         /*
  208          * text/data/bss must not exceed limits
  209          */
  210         if (                    /* text can't exceed maximum text size */
  211             gz->a_out.a_text > MAXTSIZ ||
  212 
  213         /* data + bss can't exceed rlimit */
  214             gz->a_out.a_data + gz->bss_size >
  215             gz->ip->proc->p_rlimit[RLIMIT_DATA].rlim_cur) {
  216                 gz->where = __LINE__;
  217                 return (ENOMEM);
  218         }
  219         /* Find out how far we should go */
  220         gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;
  221 
  222         /* copy in arguments and/or environment from old process */
  223         error = exec_extract_strings(gz->ip);
  224         if (error) {
  225                 gz->where = __LINE__;
  226                 return (error);
  227         }
  228         /*
  229          * Destroy old process VM and create a new one (with a new stack)
  230          */
  231         exec_new_vmspace(gz->ip);
  232 
  233         vmspace = gz->ip->proc->p_vmspace;
  234 
  235         vmaddr = gz->virtual_offset;
  236 
  237         error = vm_mmap(&vmspace->vm_map,
  238                         &vmaddr,
  239                         gz->a_out.a_text + gz->a_out.a_data,
  240                         VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
  241                         0,
  242                         0);
  243 
  244         if (error) {
  245                 gz->where = __LINE__;
  246                 return (error);
  247         }
  248 
  249         if (gz->bss_size != 0) {
  250                 /*
  251                  * Allocate demand-zeroed area for uninitialized data.
  252                  * "bss" = 'block started by symbol' - named after the 
  253                  * IBM 7090 instruction of the same name.
  254                  */
  255                 vmaddr = gz->virtual_offset + gz->a_out.a_text + 
  256                         gz->a_out.a_data;
  257                 error = vm_map_find(&vmspace->vm_map,
  258                                 NULL,
  259                                 0,
  260                                 &vmaddr, 
  261                                 gz->bss_size,
  262                                 FALSE, VM_PROT_ALL, VM_PROT_ALL, 0);
  263                 if (error) {
  264                         gz->where = __LINE__;
  265                         return (error);
  266                 }
  267         }
  268         /* Fill in process VM information */
  269         vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
  270         vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
  271         vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
  272         vmspace->vm_daddr = (caddr_t) (uintptr_t)
  273                             (gz->virtual_offset + gz->a_out.a_text);
  274 
  275         /* Fill in image_params */
  276         gz->ip->interpreted = 0;
  277         gz->ip->entry_addr = gz->a_out.a_entry;
  278 
  279         gz->ip->proc->p_sysent = &aout_sysvec;
  280 
  281         return 0;
  282 }
  283 
  284 static int
  285 NextByte(void *vp)
  286 {
  287         int             error;
  288         struct imgact_gzip *igz = (struct imgact_gzip *) vp;
  289 
  290         if (igz->idx >= igz->len) {
  291                 igz->where = __LINE__;
  292                 return GZ_EOF;
  293         }
  294         if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
  295                 return igz->inbuf[(igz->idx++) - igz->offset];
  296         }
  297         if (igz->inbuf) {
  298                 error = vm_map_remove(kernel_map, (vm_offset_t) igz->inbuf,
  299                             (vm_offset_t) igz->inbuf + PAGE_SIZE);
  300                 if (error) {
  301                         igz->where = __LINE__;
  302                         igz->error = error;
  303                         return GZ_EOF;
  304                 }
  305         }
  306         igz->offset = igz->idx & ~PAGE_MASK;
  307 
  308         error = vm_mmap(kernel_map,     /* map */
  309                         (vm_offset_t *) & igz->inbuf,   /* address */
  310                         PAGE_SIZE,      /* size */
  311                         VM_PROT_READ,   /* protection */
  312                         VM_PROT_READ,   /* max protection */
  313                         0,      /* flags */
  314                         (caddr_t) igz->ip->vp,  /* vnode */
  315                         igz->offset);   /* offset */
  316         if (error) {
  317                 igz->where = __LINE__;
  318                 igz->error = error;
  319                 return GZ_EOF;
  320         }
  321         return igz->inbuf[(igz->idx++) - igz->offset];
  322 }
  323 
  324 static int
  325 Flush(void *vp, u_char * ptr, u_long siz)
  326 {
  327         struct imgact_gzip *gz = (struct imgact_gzip *) vp;
  328         u_char         *p = ptr, *q;
  329         int             i;
  330 
  331         /* First, find a a.out-header */
  332         if (gz->output < sizeof gz->a_out) {
  333                 q = (u_char *) & gz->a_out;
  334                 i = min(siz, sizeof gz->a_out - gz->output);
  335                 bcopy(p, q + gz->output, i);
  336                 gz->output += i;
  337                 p += i;
  338                 siz -= i;
  339                 if (gz->output == sizeof gz->a_out) {
  340                         gz->gotheader = 1;
  341                         i = do_aout_hdr(gz);
  342                         if (i == -1) {
  343                                 if (!gz->where)
  344                                         gz->where = __LINE__;
  345                                 gz->error = ENOEXEC;
  346                                 return ENOEXEC;
  347                         } else if (i) {
  348                                 gz->where = __LINE__;
  349                                 gz->error = i;
  350                                 return ENOEXEC;
  351                         }
  352                         if (gz->file_offset == 0) {
  353                                 q = (u_char *) (uintptr_t) gz->virtual_offset;
  354                                 copyout(&gz->a_out, q, sizeof gz->a_out);
  355                         }
  356                 }
  357         }
  358         /* Skip over zero-padded first PAGE if needed */
  359         if (gz->output < gz->file_offset &&
  360             gz->output + siz > gz->file_offset) {
  361                 i = min(siz, gz->file_offset - gz->output);
  362                 gz->output += i;
  363                 p += i;
  364                 siz -= i;
  365         }
  366         if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
  367                 i = min(siz, gz->file_end - gz->output);
  368                 q = (u_char *) (uintptr_t)
  369                     (gz->virtual_offset + gz->output - gz->file_offset);
  370                 copyout(p, q, i);
  371                 gz->output += i;
  372                 p += i;
  373                 siz -= i;
  374         }
  375         gz->output += siz;
  376         return 0;
  377 }
  378 
  379 
  380 /*
  381  * Tell kern_execve.c about it, with a little help from the linker.
  382  * Since `const' objects end up in the text segment, TEXT_SET is the
  383  * correct directive to use.
  384  */
  385 
  386 static const struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"};
  387 EXEC_SET(execgzip, gzip_execsw);

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