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 /*
  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/cdefs.h>
  25 __FBSDID("$FreeBSD$");
  26
  27 #include <sys/param.h>
  28 #include <sys/exec.h>
  29 #include <sys/imgact.h>
  30 #include <sys/imgact_aout.h>
  31 #include <sys/kernel.h>
  32 #include <sys/lock.h>
  33 #include <sys/mman.h>
  34 #include <sys/mutex.h>
  35 #include <sys/proc.h>
  36 #include <sys/resourcevar.h>
  37 #include <sys/sysent.h>
  38 #include <sys/systm.h>
  39 #include <sys/vnode.h>
  40 #include <sys/inflate.h>
  41
  42 #include <vm/vm.h>
  43 #include <vm/vm_param.h>
  44 #include <vm/pmap.h>
  45 #include <vm/vm_map.h>
  46 #include <vm/vm_kern.h>
  47 #include <vm/vm_extern.h>
  48
  49 struct imgact_gzip {
  50         struct image_params *ip;
  51         struct exec     a_out;
  52         int             error;
  53         int             gotheader;
  54         int             where;
  55         u_char         *inbuf;
  56         u_long          offset;
  57         u_long          output;
  58         u_long          len;
  59         int             idx;
  60         u_long          virtual_offset, file_offset, file_end, bss_size;
  61 };
  62
  63 static int exec_gzip_imgact(struct image_params *imgp);
  64 static int NextByte(void *vp);
  65 static int do_aout_hdr(struct imgact_gzip *);
  66 static int Flush(void *vp, u_char *, u_long siz);
  67
  68 static int
  69 exec_gzip_imgact(imgp)
  70         struct image_params *imgp;
  71 {
  72         int             error, error2 = 0;
  73         const u_char   *p = (const u_char *) imgp->image_header;
  74         struct imgact_gzip igz;
  75         struct inflate  infl;
  76         struct vmspace *vmspace;
  77
  78         /* If these four are not OK, it isn't a gzip file */
  79         if (p[0] != 0x1f)
  80                 return -1;      /* 0    Simply magic     */
  81         if (p[1] != 0x8b)
  82                 return -1;      /* 1    Simply magic     */
  83         if (p[2] != 0x08)
  84                 return -1;      /* 2    Compression method       */
  85         if (p[9] != 0x03)
  86                 return -1;      /* 9    OS compressed on         */
  87
  88         /*
  89          * If this one contains anything but a comment or a filename marker,
  90          * we don't want to chew on it
  91          */
  92         if (p[3] & ~(0x18))
  93                 return ENOEXEC; /* 3    Flags            */
  94
  95         /* These are of no use to us */
  96         /* 4-7  Timestamp                */
  97         /* 8    Extra flags              */
  98
  99         bzero(&igz, sizeof igz);
 100         bzero(&infl, sizeof infl);
 101         infl.gz_private = (void *) &igz;
 102         infl.gz_input = NextByte;
 103         infl.gz_output = Flush;
 104
 105         igz.ip = imgp;
 106         igz.idx = 10;
 107
 108         if (p[3] & 0x08) {      /* skip a filename */
 109                 while (p[igz.idx++])
 110                         if (igz.idx >= PAGE_SIZE)
 111                                 return ENOEXEC;
 112         }
 113         if (p[3] & 0x10) {      /* skip a comment */
 114                 while (p[igz.idx++])
 115                         if (igz.idx >= PAGE_SIZE)
 116                                 return ENOEXEC;
 117         }
 118         igz.len = imgp->attr->va_size;
 119
 120         error = inflate(&infl);
 121
 122         /*
 123          * The unzipped file may not even have been long enough to contain
 124          * a header giving Flush() a chance to return error.  Check for this.
 125          */
 126         if ( !igz.gotheader )
 127                 return ENOEXEC;
 128
 129         if ( !error ) {
 130                 vmspace = imgp->proc->p_vmspace;
 131                 error = vm_map_protect(&vmspace->vm_map,
 132                         (vm_offset_t) vmspace->vm_taddr,
 133                         (vm_offset_t) (vmspace->vm_taddr +
 134                                       (vmspace->vm_tsize << PAGE_SHIFT)) ,
 135                         VM_PROT_READ|VM_PROT_EXECUTE,0);
 136         }
 137
 138         if (igz.inbuf) {
 139                 error2 =
 140                         vm_map_remove(kernel_map, (vm_offset_t) igz.inbuf,
 141                             (vm_offset_t) igz.inbuf + PAGE_SIZE);
 142         }
 143         if (igz.error || error || error2) {
 144                 printf("Output=%lu ", igz.output);
 145                 printf("Inflate_error=%d igz.error=%d error2=%d where=%d\n",
 146                        error, igz.error, error2, igz.where);
 147         }
 148         if (igz.error)
 149                 return igz.error;
 150         if (error)
 151                 return ENOEXEC;
 152         if (error2)
 153                 return error2;
 154         return 0;
 155 }
 156
 157 static int
 158 do_aout_hdr(struct imgact_gzip * gz)
 159 {
 160         int             error;
 161         struct thread  *td = curthread;
 162         struct vmspace *vmspace;
 163         vm_offset_t     vmaddr;
 164
 165         /*
 166          * Set file/virtual offset based on a.out variant. We do two cases:
 167          * host byte order and network byte order (for NetBSD compatibility)
 168          */
 169         switch ((int) (gz->a_out.a_magic & 0xffff)) {
 170         case ZMAGIC:
 171                 gz->virtual_offset = 0;
 172                 if (gz->a_out.a_text) {
 173                         gz->file_offset = PAGE_SIZE;
 174                 } else {
 175                         /* Bill's "screwball mode" */
 176                         gz->file_offset = 0;
 177                 }
 178                 break;
 179         case QMAGIC:
 180                 gz->virtual_offset = PAGE_SIZE;
 181                 gz->file_offset = 0;
 182                 break;
 183         default:
 184                 /* NetBSD compatibility */
 185                 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) {
 186                 case ZMAGIC:
 187                 case QMAGIC:
 188                         gz->virtual_offset = PAGE_SIZE;
 189                         gz->file_offset = 0;
 190                         break;
 191                 default:
 192                         gz->where = __LINE__;
 193                         return (-1);
 194                 }
 195         }
 196
 197         gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE);
 198
 199         /*
 200          * Check various fields in header for validity/bounds.
 201          */
 202         if (                    /* entry point must lay with text region */
 203             gz->a_out.a_entry < gz->virtual_offset ||
 204             gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text ||
 205
 206         /* text and data size must each be page rounded */
 207             gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) {
 208                 gz->where = __LINE__;
 209                 return (-1);
 210         }
 211         /*
 212          * text/data/bss must not exceed limits
 213          */
 214         PROC_LOCK(gz->ip->proc);
 215         if (                    /* text can't exceed maximum text size */
 216             gz->a_out.a_text > maxtsiz ||
 217
 218         /* data + bss can't exceed rlimit */
 219             gz->a_out.a_data + gz->bss_size >
 220             lim_cur(gz->ip->proc, RLIMIT_DATA)) {
 221                 PROC_UNLOCK(gz->ip->proc);
 222                 gz->where = __LINE__;
 223                 return (ENOMEM);
 224         }
 225         PROC_UNLOCK(gz->ip->proc);
 226         /* Find out how far we should go */
 227         gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data;
 228
 229         /*
 230          * Avoid a possible deadlock if the current address space is destroyed
 231          * and that address space maps the locked vnode.  In the common case,
 232          * the locked vnode's v_usecount is decremented but remains greater
 233          * than zero.  Consequently, the vnode lock is not needed by vrele().
 234          * However, in cases where the vnode lock is external, such as nullfs,
 235          * v_usecount may become zero.
 236          */
 237         VOP_UNLOCK(gz->ip->vp, 0, td);
 238
 239         /*
 240          * Destroy old process VM and create a new one (with a new stack)
 241          */
 242         error = exec_new_vmspace(gz->ip, &aout_sysvec);
 243
 244         vn_lock(gz->ip->vp, LK_EXCLUSIVE | LK_RETRY, td);
 245         if (error) {
 246                 gz->where = __LINE__;
 247                 return (error);
 248         }
 249
 250         vmspace = gz->ip->proc->p_vmspace;
 251
 252         vmaddr = gz->virtual_offset;
 253
 254         error = vm_mmap(&vmspace->vm_map,
 255                         &vmaddr,
 256                         gz->a_out.a_text + gz->a_out.a_data,
 257                         VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
 258                         OBJT_DEFAULT,
 259                         NULL,
 260                         0);
 261
 262         if (error) {
 263                 gz->where = __LINE__;
 264                 return (error);
 265         }
 266
 267         if (gz->bss_size != 0) {
 268                 /*
 269                  * Allocate demand-zeroed area for uninitialized data.
 270                  * "bss" = 'block started by symbol' - named after the
 271                  * IBM 7090 instruction of the same name.
 272                  */
 273                 vmaddr = gz->virtual_offset + gz->a_out.a_text +
 274                         gz->a_out.a_data;
 275                 error = vm_map_find(&vmspace->vm_map,
 276                                 NULL,
 277                                 0,
 278                                 &vmaddr,
 279                                 gz->bss_size,
 280                                 FALSE, VM_PROT_ALL, VM_PROT_ALL, 0);
 281                 if (error) {
 282                         gz->where = __LINE__;
 283                         return (error);
 284                 }
 285         }
 286         /* Fill in process VM information */
 287         vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
 288         vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
 289         vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
 290         vmspace->vm_daddr = (caddr_t) (uintptr_t)
 291                             (gz->virtual_offset + gz->a_out.a_text);
 292
 293         /* Fill in image_params */
 294         gz->ip->interpreted = 0;
 295         gz->ip->entry_addr = gz->a_out.a_entry;
 296
 297         gz->ip->proc->p_sysent = &aout_sysvec;
 298
 299         return 0;
 300 }
 301
 302 static int
 303 NextByte(void *vp)
 304 {
 305         int             error;
 306         struct imgact_gzip *igz = (struct imgact_gzip *) vp;
 307
 308         if (igz->idx >= igz->len) {
 309                 igz->where = __LINE__;
 310                 return GZ_EOF;
 311         }
 312         if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
 313                 return igz->inbuf[(igz->idx++) - igz->offset];
 314         }
 315         if (igz->inbuf) {
 316                 error = vm_map_remove(kernel_map, (vm_offset_t) igz->inbuf,
 317                             (vm_offset_t) igz->inbuf + PAGE_SIZE);
 318                 if (error) {
 319                         igz->where = __LINE__;
 320                         igz->error = error;
 321                         return GZ_EOF;
 322                 }
 323         }
 324         igz->offset = igz->idx & ~PAGE_MASK;
 325
 326         error = vm_mmap(kernel_map,     /* map */
 327                         (vm_offset_t *) & igz->inbuf,   /* address */
 328                         PAGE_SIZE,      /* size */
 329                         VM_PROT_READ,   /* protection */
 330                         VM_PROT_READ,   /* max protection */
 331                         0,      /* flags */
 332                         OBJT_VNODE,     /* handle type */
 333                         igz->ip->vp,    /* vnode */
 334                         igz->offset);   /* offset */
 335         if (error) {
 336                 igz->where = __LINE__;
 337                 igz->error = error;
 338                 return GZ_EOF;
 339         }
 340         return igz->inbuf[(igz->idx++) - igz->offset];
 341 }
 342
 343 static int
 344 Flush(void *vp, u_char * ptr, u_long siz)
 345 {
 346         struct imgact_gzip *gz = (struct imgact_gzip *) vp;
 347         u_char         *p = ptr, *q;
 348         int             i;
 349
 350         /* First, find an a.out-header. */
 351         if (gz->output < sizeof gz->a_out) {
 352                 q = (u_char *) & gz->a_out;
 353                 i = min(siz, sizeof gz->a_out - gz->output);
 354                 bcopy(p, q + gz->output, i);
 355                 gz->output += i;
 356                 p += i;
 357                 siz -= i;
 358                 if (gz->output == sizeof gz->a_out) {
 359                         gz->gotheader = 1;
 360                         i = do_aout_hdr(gz);
 361                         if (i == -1) {
 362                                 if (!gz->where)
 363                                         gz->where = __LINE__;
 364                                 gz->error = ENOEXEC;
 365                                 return ENOEXEC;
 366                         } else if (i) {
 367                                 gz->where = __LINE__;
 368                                 gz->error = i;
 369                                 return ENOEXEC;
 370                         }
 371                         if (gz->file_offset == 0) {
 372                                 q = (u_char *) (uintptr_t) gz->virtual_offset;
 373                                 copyout(&gz->a_out, q, sizeof gz->a_out);
 374                         }
 375                 }
 376         }
 377         /* Skip over zero-padded first PAGE if needed */
 378         if (gz->output < gz->file_offset &&
 379             gz->output + siz > gz->file_offset) {
 380                 i = min(siz, gz->file_offset - gz->output);
 381                 gz->output += i;
 382                 p += i;
 383                 siz -= i;
 384         }
 385         if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
 386                 i = min(siz, gz->file_end - gz->output);
 387                 q = (u_char *) (uintptr_t)
 388                     (gz->virtual_offset + gz->output - gz->file_offset);
 389                 copyout(p, q, i);
 390                 gz->output += i;
 391                 p += i;
 392                 siz -= i;
 393         }
 394         gz->output += siz;
 395         return 0;
 396 }
 397
 398
 399 /*
 400  * Tell kern_execve.c about it, with a little help from the linker.
 401  */
 402 static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"};
 403 EXEC_SET(execgzip, gzip_execsw);