Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/imgact_gzip.c
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1 /* 2 * ---------------------------------------------------------------------------- 3 * "THE BEER-WARE LICENSE" (Revision 42): 4 * <phk@login.dkuug.dk> 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 * $FreeBSD: src/sys/kern/imgact_gzip.c,v 1.40.2.1 2001/11/03 01:41:08 ps Exp $ 10 * $DragonFly: src/sys/kern/imgact_gzip.c,v 1.9 2006/12/28 21:24:01 dillon Exp $ 11 * 12 * This module handles execution of a.out files which have been run through 13 * "gzip". This saves diskspace, but wastes cpu-cycles and VM. 14 * 15 * TODO: 16 * text-segments should be made R/O after being filled 17 * is the vm-stuff safe ? 18 * should handle the entire header of gzip'ed stuff. 19 * inflate isn't quite reentrant yet... 20 * error-handling is a mess... 21 * so is the rest... 22 * tidy up unnecesary includes 23 */ 24 25 #include <sys/param.h> 26 #include <sys/exec.h> 27 #include <sys/imgact.h> 28 #include <sys/imgact_aout.h> 29 #include <sys/kernel.h> 30 #include <sys/mman.h> 31 #include <sys/proc.h> 32 #include <sys/resourcevar.h> 33 #include <sys/sysent.h> 34 #include <sys/systm.h> 35 #include <sys/vnode.h> 36 #include <sys/inflate.h> 37 38 #include <vm/vm.h> 39 #include <vm/vm_param.h> 40 #include <sys/lock.h> 41 #include <vm/pmap.h> 42 #include <vm/vm_map.h> 43 #include <vm/vm_kern.h> 44 #include <vm/vm_extern.h> 45 46 struct imgact_gzip { 47 struct image_params *ip; 48 struct exec a_out; 49 int error; 50 int gotheader; 51 int where; 52 u_char *inbuf; 53 u_long offset; 54 u_long output; 55 u_long len; 56 int idx; 57 u_long virtual_offset, file_offset, file_end, bss_size; 58 }; 59 60 static int exec_gzip_imgact (struct image_params *imgp); 61 static int NextByte (void *vp); 62 static int do_aout_hdr (struct imgact_gzip *); 63 static int Flush (void *vp, u_char *, u_long siz); 64 65 static int 66 exec_gzip_imgact(struct image_params *imgp) 67 { 68 int error, error2 = 0; 69 const u_char *p = (const u_char *) imgp->image_header; 70 struct imgact_gzip igz; 71 struct inflate infl; 72 struct vmspace *vmspace; 73 74 /* If these four are not OK, it isn't a gzip file */ 75 if (p[0] != 0x1f) 76 return -1; /* 0 Simply magic */ 77 if (p[1] != 0x8b) 78 return -1; /* 1 Simply magic */ 79 if (p[2] != 0x08) 80 return -1; /* 2 Compression method */ 81 if (p[9] != 0x03) 82 return -1; /* 9 OS compressed on */ 83 84 /* 85 * If this one contains anything but a comment or a filename marker, 86 * we don't want to chew on it 87 */ 88 if (p[3] & ~(0x18)) 89 return ENOEXEC; /* 3 Flags */ 90 91 /* These are of no use to us */ 92 /* 4-7 Timestamp */ 93 /* 8 Extra flags */ 94 95 bzero(&igz, sizeof igz); 96 bzero(&infl, sizeof infl); 97 infl.gz_private = (void *) &igz; 98 infl.gz_input = NextByte; 99 infl.gz_output = Flush; 100 101 igz.ip = imgp; 102 igz.idx = 10; 103 104 if (p[3] & 0x08) { /* skip a filename */ 105 while (p[igz.idx++]) 106 if (igz.idx >= PAGE_SIZE) 107 return ENOEXEC; 108 } 109 if (p[3] & 0x10) { /* skip a comment */ 110 while (p[igz.idx++]) 111 if (igz.idx >= PAGE_SIZE) 112 return ENOEXEC; 113 } 114 igz.len = imgp->attr->va_size; 115 116 error = inflate(&infl); 117 118 /* 119 * The unzipped file may not even have been long enough to contain 120 * a header giving Flush() a chance to return error. Check for this. 121 */ 122 if ( !igz.gotheader ) 123 return ENOEXEC; 124 125 if ( !error ) { 126 vmspace = imgp->proc->p_vmspace; 127 error = vm_map_protect(&vmspace->vm_map, 128 (vm_offset_t) vmspace->vm_taddr, 129 (vm_offset_t) (vmspace->vm_taddr + 130 (vmspace->vm_tsize << PAGE_SHIFT)) , 131 VM_PROT_READ|VM_PROT_EXECUTE,0); 132 } 133 134 if (igz.inbuf) { 135 error2 = vm_map_remove(&kernel_map, (vm_offset_t)igz.inbuf, 136 (vm_offset_t)igz.inbuf + PAGE_SIZE); 137 } 138 if (igz.error || error || error2) { 139 kprintf("Output=%lu ", igz.output); 140 kprintf("Inflate_error=%d igz.error=%d error2=%d where=%d\n", 141 error, igz.error, error2, igz.where); 142 } 143 if (igz.error) 144 return igz.error; 145 if (error) 146 return ENOEXEC; 147 if (error2) 148 return error2; 149 return 0; 150 } 151 152 static int 153 do_aout_hdr(struct imgact_gzip * gz) 154 { 155 int error; 156 struct vmspace *vmspace; 157 vm_offset_t vmaddr; 158 159 /* 160 * Set file/virtual offset based on a.out variant. We do two cases: 161 * host byte order and network byte order (for NetBSD compatibility) 162 */ 163 switch ((int) (gz->a_out.a_magic & 0xffff)) { 164 case ZMAGIC: 165 gz->virtual_offset = 0; 166 if (gz->a_out.a_text) { 167 gz->file_offset = PAGE_SIZE; 168 } else { 169 /* Bill's "screwball mode" */ 170 gz->file_offset = 0; 171 } 172 break; 173 case QMAGIC: 174 gz->virtual_offset = PAGE_SIZE; 175 gz->file_offset = 0; 176 break; 177 default: 178 /* NetBSD compatibility */ 179 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) { 180 case ZMAGIC: 181 case QMAGIC: 182 gz->virtual_offset = PAGE_SIZE; 183 gz->file_offset = 0; 184 break; 185 default: 186 gz->where = __LINE__; 187 return (-1); 188 } 189 } 190 191 gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE); 192 193 /* 194 * Check various fields in header for validity/bounds. 195 */ 196 if ( /* entry point must lay with text region */ 197 gz->a_out.a_entry < gz->virtual_offset || 198 gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text || 199 200 /* text and data size must each be page rounded */ 201 gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) { 202 gz->where = __LINE__; 203 return (-1); 204 } 205 /* 206 * text/data/bss must not exceed limits 207 */ 208 if ( /* text can't exceed maximum text size */ 209 gz->a_out.a_text > maxtsiz || 210 211 /* data + bss can't exceed rlimit */ 212 gz->a_out.a_data + gz->bss_size > 213 gz->ip->proc->p_rlimit[RLIMIT_DATA].rlim_cur) { 214 gz->where = __LINE__; 215 return (ENOMEM); 216 } 217 /* Find out how far we should go */ 218 gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data; 219 220 /* 221 * Destroy old process VM and create a new one (with a new stack) 222 */ 223 exec_new_vmspace(gz->ip, NULL); 224 225 vmspace = gz->ip->proc->p_vmspace; 226 227 vmaddr = gz->virtual_offset; 228 229 error = vm_mmap(&vmspace->vm_map, 230 &vmaddr, 231 gz->a_out.a_text + gz->a_out.a_data, 232 VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED, 233 0, 234 0); 235 236 if (error) { 237 gz->where = __LINE__; 238 return (error); 239 } 240 241 if (gz->bss_size != 0) { 242 /* 243 * Allocate demand-zeroed area for uninitialized data. 244 * "bss" = 'block started by symbol' - named after the 245 * IBM 7090 instruction of the same name. 246 */ 247 vmaddr = gz->virtual_offset + gz->a_out.a_text + 248 gz->a_out.a_data; 249 error = vm_map_find(&vmspace->vm_map, 250 NULL, 0, 251 &vmaddr, gz->bss_size, PAGE_SIZE, 252 FALSE, VM_MAPTYPE_NORMAL, 253 VM_PROT_ALL, VM_PROT_ALL, 254 0); 255 if (error) { 256 gz->where = __LINE__; 257 return (error); 258 } 259 } 260 /* Fill in process VM information */ 261 vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT; 262 vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT; 263 vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset; 264 vmspace->vm_daddr = (caddr_t) (uintptr_t) 265 (gz->virtual_offset + gz->a_out.a_text); 266 267 /* Fill in image_params */ 268 gz->ip->interpreted = 0; 269 gz->ip->entry_addr = gz->a_out.a_entry; 270 271 gz->ip->proc->p_sysent = &aout_sysvec; 272 273 return 0; 274 } 275 276 static int 277 NextByte(void *vp) 278 { 279 int error; 280 struct imgact_gzip *igz = (struct imgact_gzip *) vp; 281 282 if (igz->idx >= igz->len) { 283 igz->where = __LINE__; 284 return GZ_EOF; 285 } 286 if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) { 287 return igz->inbuf[(igz->idx++) - igz->offset]; 288 } 289 if (igz->inbuf) { 290 error = vm_map_remove(&kernel_map, (vm_offset_t)igz->inbuf, 291 (vm_offset_t)igz->inbuf + PAGE_SIZE); 292 if (error) { 293 igz->where = __LINE__; 294 igz->error = error; 295 return GZ_EOF; 296 } 297 } 298 igz->offset = igz->idx & ~PAGE_MASK; 299 300 error = vm_mmap(&kernel_map, /* map */ 301 (vm_offset_t *) & igz->inbuf, /* address */ 302 PAGE_SIZE, /* size */ 303 VM_PROT_READ, /* protection */ 304 VM_PROT_READ, /* max protection */ 305 0, /* flags */ 306 (caddr_t) igz->ip->vp, /* vnode */ 307 igz->offset); /* offset */ 308 if (error) { 309 igz->where = __LINE__; 310 igz->error = error; 311 return GZ_EOF; 312 } 313 return igz->inbuf[(igz->idx++) - igz->offset]; 314 } 315 316 static int 317 Flush(void *vp, u_char * ptr, u_long siz) 318 { 319 struct imgact_gzip *gz = (struct imgact_gzip *) vp; 320 u_char *p = ptr, *q; 321 int i; 322 323 /* First, find a a.out-header */ 324 if (gz->output < sizeof gz->a_out) { 325 q = (u_char *) & gz->a_out; 326 i = min(siz, sizeof gz->a_out - gz->output); 327 bcopy(p, q + gz->output, i); 328 gz->output += i; 329 p += i; 330 siz -= i; 331 if (gz->output == sizeof gz->a_out) { 332 gz->gotheader = 1; 333 i = do_aout_hdr(gz); 334 if (i == -1) { 335 if (!gz->where) 336 gz->where = __LINE__; 337 gz->error = ENOEXEC; 338 return ENOEXEC; 339 } else if (i) { 340 gz->where = __LINE__; 341 gz->error = i; 342 return ENOEXEC; 343 } 344 if (gz->file_offset == 0) { 345 q = (u_char *) (uintptr_t) gz->virtual_offset; 346 copyout(&gz->a_out, q, sizeof gz->a_out); 347 } 348 } 349 } 350 /* Skip over zero-padded first PAGE if needed */ 351 if (gz->output < gz->file_offset && 352 gz->output + siz > gz->file_offset) { 353 i = min(siz, gz->file_offset - gz->output); 354 gz->output += i; 355 p += i; 356 siz -= i; 357 } 358 if (gz->output >= gz->file_offset && gz->output < gz->file_end) { 359 i = min(siz, gz->file_end - gz->output); 360 q = (u_char *) (uintptr_t) 361 (gz->virtual_offset + gz->output - gz->file_offset); 362 copyout(p, q, i); 363 gz->output += i; 364 p += i; 365 siz -= i; 366 } 367 gz->output += siz; 368 return 0; 369 } 370 371 372 /* 373 * Tell kern_execve.c about it, with a little help from the linker. 374 */ 375 static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"}; 376 EXEC_SET(execgzip, gzip_execsw);
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