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