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