sys/kern/imgact_gzip.c

   1 /*-
   2  * SPDX-License-Identifier: Beerware
   3  *
   4  * ----------------------------------------------------------------------------
   5  * "THE BEER-WARE LICENSE" (Revision 42):
   6  * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
   7  * can do whatever you want with this stuff. If we meet some day, and you think
   8  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
   9  * ----------------------------------------------------------------------------
  10  */
  11
  12 /*
  13  * This module handles execution of a.out files which have been run through
  14  * "gzip".  This saves diskspace, but wastes cpu-cycles and VM.
  15  *
  16  * TODO:
  17  *      text-segments should be made R/O after being filled
  18  *      is the vm-stuff safe ?
  19  *      should handle the entire header of gzip'ed stuff.
  20  *      inflate isn't quite reentrant yet...
  21  *      error-handling is a mess...
  22  *      so is the rest...
  23  *      tidy up unnecessary includes
  24  */
  25
  26 #include <sys/cdefs.h>
  27 __FBSDID("$FreeBSD$");
  28
  29 #include <sys/param.h>
  30 #include <sys/exec.h>
  31 #include <sys/imgact.h>
  32 #include <sys/imgact_aout.h>
  33 #include <sys/kernel.h>
  34 #include <sys/lock.h>
  35 #include <sys/mman.h>
  36 #include <sys/mutex.h>
  37 #include <sys/proc.h>
  38 #include <sys/racct.h>
  39 #include <sys/resourcevar.h>
  40 #include <sys/sysent.h>
  41 #include <sys/systm.h>
  42 #include <sys/vnode.h>
  43 #include <sys/inflate.h>
  44
  45 #include <vm/vm.h>
  46 #include <vm/vm_param.h>
  47 #include <vm/pmap.h>
  48 #include <vm/vm_map.h>
  49 #include <vm/vm_kern.h>
  50 #include <vm/vm_extern.h>
  51
  52 struct imgact_gzip {
  53         struct image_params *ip;
  54         struct exec     a_out;
  55         int             error;
  56         int             gotheader;
  57         int             where;
  58         u_char         *inbuf;
  59         u_long          offset;
  60         u_long          output;
  61         u_long          len;
  62         int             idx;
  63         u_long          virtual_offset, file_offset, file_end, bss_size;
  64 };
  65
  66 static int exec_gzip_imgact(struct image_params *imgp);
  67 static int NextByte(void *vp);
  68 static int do_aout_hdr(struct imgact_gzip *);
  69 static int Flush(void *vp, u_char *, u_long siz);
  70
  71 static int
  72 exec_gzip_imgact(struct image_params *imgp)
  73 {
  74         int             error;
  75         const u_char   *p = (const u_char *) imgp->image_header;
  76         struct imgact_gzip igz;
  77         struct inflate  infl;
  78         struct vmspace *vmspace;
  79
  80         /* If these four are not OK, it isn't a gzip file */
  81         if (p[0] != 0x1f)
  82                 return -1;      /* 0    Simply magic     */
  83         if (p[1] != 0x8b)
  84                 return -1;      /* 1    Simply magic     */
  85         if (p[2] != 0x08)
  86                 return -1;      /* 2    Compression method       */
  87         if (p[9] != 0x03)
  88                 return -1;      /* 9    OS compressed on         */
  89
  90         /*
  91          * If this one contains anything but a comment or a filename marker,
  92          * we don't want to chew on it
  93          */
  94         if (p[3] & ~(0x18))
  95                 return ENOEXEC; /* 3    Flags            */
  96
  97         /* These are of no use to us */
  98         /* 4-7  Timestamp                */
  99         /* 8    Extra flags              */
 100
 101         bzero(&igz, sizeof igz);
 102         bzero(&infl, sizeof infl);
 103         infl.gz_private = (void *) &igz;
 104         infl.gz_input = NextByte;
 105         infl.gz_output = Flush;
 106
 107         igz.ip = imgp;
 108         igz.idx = 10;
 109
 110         if (p[3] & 0x08) {      /* skip a filename */
 111                 while (p[igz.idx++])
 112                         if (igz.idx >= PAGE_SIZE)
 113                                 return ENOEXEC;
 114         }
 115         if (p[3] & 0x10) {      /* skip a comment */
 116                 while (p[igz.idx++])
 117                         if (igz.idx >= PAGE_SIZE)
 118                                 return ENOEXEC;
 119         }
 120         igz.len = imgp->attr->va_size;
 121
 122         error = inflate(&infl);
 123
 124         /*
 125          * The unzipped file may not even have been long enough to contain
 126          * a header giving Flush() a chance to return error.  Check for this.
 127          */
 128         if ( !igz.gotheader )
 129                 return ENOEXEC;
 130
 131         if ( !error ) {
 132                 vmspace = imgp->proc->p_vmspace;
 133                 error = vm_map_protect(&vmspace->vm_map,
 134                         (vm_offset_t) vmspace->vm_taddr,
 135                         (vm_offset_t) (vmspace->vm_taddr +
 136                                       (vmspace->vm_tsize << PAGE_SHIFT)) ,
 137                         VM_PROT_READ|VM_PROT_EXECUTE,0);
 138         }
 139
 140         if (igz.inbuf)
 141                 kmap_free_wakeup(exec_map, (vm_offset_t)igz.inbuf, PAGE_SIZE);
 142         if (igz.error || error) {
 143                 printf("Output=%lu ", igz.output);
 144                 printf("Inflate_error=%d igz.error=%d where=%d\n",
 145                        error, igz.error, igz.where);
 146         }
 147         if (igz.error)
 148                 return igz.error;
 149         if (error)
 150                 return ENOEXEC;
 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_midmag & 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_midmag) & 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         PROC_LOCK(gz->ip->proc);
 211         if (                    /* text can't exceed maximum text size */
 212             gz->a_out.a_text > maxtsiz ||
 213
 214         /* data + bss can't exceed rlimit */
 215             gz->a_out.a_data + gz->bss_size >
 216             lim_cur_proc(gz->ip->proc, RLIMIT_DATA) ||
 217             racct_set(gz->ip->proc, RACCT_DATA,
 218             gz->a_out.a_data + gz->bss_size) != 0) {
 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         /*
 228          * Avoid a possible deadlock if the current address space is destroyed
 229          * and that address space maps the locked vnode.  In the common case,
 230          * the locked vnode's v_usecount is decremented but remains greater
 231          * than zero.  Consequently, the vnode lock is not needed by vrele().
 232          * However, in cases where the vnode lock is external, such as nullfs,
 233          * v_usecount may become zero.
 234          */
 235         VOP_UNLOCK(gz->ip->vp, 0);
 236
 237         /*
 238          * Destroy old process VM and create a new one (with a new stack)
 239          */
 240         error = exec_new_vmspace(gz->ip, &aout_sysvec);
 241
 242         vn_lock(gz->ip->vp, LK_EXCLUSIVE | LK_RETRY);
 243         if (error) {
 244                 gz->where = __LINE__;
 245                 return (error);
 246         }
 247
 248         vmspace = gz->ip->proc->p_vmspace;
 249
 250         vmaddr = gz->virtual_offset;
 251
 252         error = vm_mmap(&vmspace->vm_map,
 253                         &vmaddr,
 254                         gz->a_out.a_text + gz->a_out.a_data,
 255                         VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED,
 256                         OBJT_DEFAULT,
 257                         NULL,
 258                         0);
 259
 260         if (error) {
 261                 gz->where = __LINE__;
 262                 return (error);
 263         }
 264
 265         if (gz->bss_size != 0) {
 266                 /*
 267                  * Allocate demand-zeroed area for uninitialized data.
 268                  * "bss" = 'block started by symbol' - named after the
 269                  * IBM 7090 instruction of the same name.
 270                  */
 271                 vmaddr = gz->virtual_offset + gz->a_out.a_text +
 272                         gz->a_out.a_data;
 273                 error = vm_map_find(&vmspace->vm_map, NULL, 0, &vmaddr,
 274                     gz->bss_size, 0, VMFS_NO_SPACE, VM_PROT_ALL, VM_PROT_ALL,
 275                     0);
 276                 if (error) {
 277                         gz->where = __LINE__;
 278                         return (error);
 279                 }
 280         }
 281         /* Fill in process VM information */
 282         vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT;
 283         vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT;
 284         vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset;
 285         vmspace->vm_daddr = (caddr_t) (uintptr_t)
 286                             (gz->virtual_offset + gz->a_out.a_text);
 287
 288         /* Fill in image_params */
 289         gz->ip->interpreted = 0;
 290         gz->ip->entry_addr = gz->a_out.a_entry;
 291
 292         gz->ip->proc->p_sysent = &aout_sysvec;
 293
 294         return 0;
 295 }
 296
 297 static int
 298 NextByte(void *vp)
 299 {
 300         int             error;
 301         struct imgact_gzip *igz = (struct imgact_gzip *) vp;
 302
 303         if (igz->idx >= igz->len) {
 304                 igz->where = __LINE__;
 305                 return GZ_EOF;
 306         }
 307         if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) {
 308                 return igz->inbuf[(igz->idx++) - igz->offset];
 309         }
 310         if (igz->inbuf)
 311                 kmap_free_wakeup(exec_map, (vm_offset_t)igz->inbuf, PAGE_SIZE);
 312         igz->offset = igz->idx & ~PAGE_MASK;
 313
 314         error = vm_mmap(exec_map,       /* map */
 315                         (vm_offset_t *) & igz->inbuf,   /* address */
 316                         PAGE_SIZE,      /* size */
 317                         VM_PROT_READ,   /* protection */
 318                         VM_PROT_READ,   /* max protection */
 319                         0,      /* flags */
 320                         OBJT_VNODE,     /* handle type */
 321                         igz->ip->vp,    /* vnode */
 322                         igz->offset);   /* offset */
 323         if (error) {
 324                 igz->where = __LINE__;
 325                 igz->error = error;
 326                 return GZ_EOF;
 327         }
 328         return igz->inbuf[(igz->idx++) - igz->offset];
 329 }
 330
 331 static int
 332 Flush(void *vp, u_char * ptr, u_long siz)
 333 {
 334         struct imgact_gzip *gz = (struct imgact_gzip *) vp;
 335         u_char         *p = ptr, *q;
 336         int             i;
 337
 338         /* First, find an a.out-header. */
 339         if (gz->output < sizeof gz->a_out) {
 340                 q = (u_char *) & gz->a_out;
 341                 i = min(siz, sizeof gz->a_out - gz->output);
 342                 bcopy(p, q + gz->output, i);
 343                 gz->output += i;
 344                 p += i;
 345                 siz -= i;
 346                 if (gz->output == sizeof gz->a_out) {
 347                         gz->gotheader = 1;
 348                         i = do_aout_hdr(gz);
 349                         if (i == -1) {
 350                                 if (!gz->where)
 351                                         gz->where = __LINE__;
 352                                 gz->error = ENOEXEC;
 353                                 return ENOEXEC;
 354                         } else if (i) {
 355                                 gz->where = __LINE__;
 356                                 gz->error = i;
 357                                 return ENOEXEC;
 358                         }
 359                         if (gz->file_offset == 0) {
 360                                 q = (u_char *) (uintptr_t) gz->virtual_offset;
 361                                 copyout(&gz->a_out, q, sizeof gz->a_out);
 362                         }
 363                 }
 364         }
 365         /* Skip over zero-padded first PAGE if needed */
 366         if (gz->output < gz->file_offset &&
 367             gz->output + siz > gz->file_offset) {
 368                 i = min(siz, gz->file_offset - gz->output);
 369                 gz->output += i;
 370                 p += i;
 371                 siz -= i;
 372         }
 373         if (gz->output >= gz->file_offset && gz->output < gz->file_end) {
 374                 i = min(siz, gz->file_end - gz->output);
 375                 q = (u_char *) (uintptr_t)
 376                     (gz->virtual_offset + gz->output - gz->file_offset);
 377                 copyout(p, q, i);
 378                 gz->output += i;
 379                 p += i;
 380                 siz -= i;
 381         }
 382         gz->output += siz;
 383         return 0;
 384 }
 385
 386
 387 /*
 388  * Tell kern_execve.c about it, with a little help from the linker.
 389  */
 390 static struct execsw gzip_execsw = {
 391         .ex_imgact = exec_gzip_imgact,
 392         .ex_name = "gzip"
 393 };
 394 EXEC_SET(execgzip, gzip_execsw);