sys/kern/imgact_gzip.c

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