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 * $FreeBSD$ 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/param.h> 25 #include <sys/exec.h> 26 #include <sys/imgact.h> 27 #include <sys/imgact_aout.h> 28 #include <sys/kernel.h> 29 #include <sys/mman.h> 30 #include <sys/proc.h> 31 #include <sys/resourcevar.h> 32 #include <sys/sysent.h> 33 #include <sys/systm.h> 34 #include <sys/vnode.h> 35 #include <sys/inflate.h> 36 37 #include <vm/vm.h> 38 #include <vm/vm_param.h> 39 #include <sys/lock.h> 40 #include <vm/pmap.h> 41 #include <vm/vm_map.h> 42 #include <vm/vm_kern.h> 43 #include <vm/vm_extern.h> 44 45 struct imgact_gzip { 46 struct image_params *ip; 47 struct exec a_out; 48 int error; 49 int gotheader; 50 int where; 51 u_char *inbuf; 52 u_long offset; 53 u_long output; 54 u_long len; 55 int idx; 56 u_long virtual_offset, file_offset, file_end, bss_size; 57 }; 58 59 static int exec_gzip_imgact __P((struct image_params *imgp)); 60 static int NextByte __P((void *vp)); 61 static int do_aout_hdr __P((struct imgact_gzip *)); 62 static int Flush __P((void *vp, u_char *, u_long siz)); 63 64 static int 65 exec_gzip_imgact(imgp) 66 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 = 136 vm_map_remove(kernel_map, (vm_offset_t) igz.inbuf, 137 (vm_offset_t) igz.inbuf + PAGE_SIZE); 138 } 139 if (igz.error || error || error2) { 140 printf("Output=%lu ", igz.output); 141 printf("Inflate_error=%d igz.error=%d error2=%d where=%d\n", 142 error, igz.error, error2, igz.where); 143 } 144 if (igz.error) 145 return igz.error; 146 if (error) 147 return ENOEXEC; 148 if (error2) 149 return error2; 150 return 0; 151 } 152 153 static int 154 do_aout_hdr(struct imgact_gzip * gz) 155 { 156 int error; 157 struct vmspace *vmspace; 158 vm_offset_t vmaddr; 159 160 /* 161 * Set file/virtual offset based on a.out variant. We do two cases: 162 * host byte order and network byte order (for NetBSD compatibility) 163 */ 164 switch ((int) (gz->a_out.a_magic & 0xffff)) { 165 case ZMAGIC: 166 gz->virtual_offset = 0; 167 if (gz->a_out.a_text) { 168 gz->file_offset = PAGE_SIZE; 169 } else { 170 /* Bill's "screwball mode" */ 171 gz->file_offset = 0; 172 } 173 break; 174 case QMAGIC: 175 gz->virtual_offset = PAGE_SIZE; 176 gz->file_offset = 0; 177 break; 178 default: 179 /* NetBSD compatibility */ 180 switch ((int) (ntohl(gz->a_out.a_magic) & 0xffff)) { 181 case ZMAGIC: 182 case QMAGIC: 183 gz->virtual_offset = PAGE_SIZE; 184 gz->file_offset = 0; 185 break; 186 default: 187 gz->where = __LINE__; 188 return (-1); 189 } 190 } 191 192 gz->bss_size = roundup(gz->a_out.a_bss, PAGE_SIZE); 193 194 /* 195 * Check various fields in header for validity/bounds. 196 */ 197 if ( /* entry point must lay with text region */ 198 gz->a_out.a_entry < gz->virtual_offset || 199 gz->a_out.a_entry >= gz->virtual_offset + gz->a_out.a_text || 200 201 /* text and data size must each be page rounded */ 202 gz->a_out.a_text & PAGE_MASK || gz->a_out.a_data & PAGE_MASK) { 203 gz->where = __LINE__; 204 return (-1); 205 } 206 /* 207 * text/data/bss must not exceed limits 208 */ 209 if ( /* text can't exceed maximum text size */ 210 gz->a_out.a_text > maxtsiz || 211 212 /* data + bss can't exceed rlimit */ 213 gz->a_out.a_data + gz->bss_size > 214 gz->ip->proc->p_rlimit[RLIMIT_DATA].rlim_cur) { 215 gz->where = __LINE__; 216 return (ENOMEM); 217 } 218 /* Find out how far we should go */ 219 gz->file_end = gz->file_offset + gz->a_out.a_text + gz->a_out.a_data; 220 221 /* copy in arguments and/or environment from old process */ 222 error = exec_extract_strings(gz->ip); 223 if (error) { 224 gz->where = __LINE__; 225 return (error); 226 } 227 /* 228 * Destroy old process VM and create a new one (with a new stack) 229 */ 230 exec_new_vmspace(gz->ip); 231 232 vmspace = gz->ip->proc->p_vmspace; 233 234 vmaddr = gz->virtual_offset; 235 236 error = vm_mmap(&vmspace->vm_map, 237 &vmaddr, 238 gz->a_out.a_text + gz->a_out.a_data, 239 VM_PROT_ALL, VM_PROT_ALL, MAP_ANON | MAP_FIXED, 240 0, 241 0); 242 243 if (error) { 244 gz->where = __LINE__; 245 return (error); 246 } 247 248 if (gz->bss_size != 0) { 249 /* 250 * Allocate demand-zeroed area for uninitialized data. 251 * "bss" = 'block started by symbol' - named after the 252 * IBM 7090 instruction of the same name. 253 */ 254 vmaddr = gz->virtual_offset + gz->a_out.a_text + 255 gz->a_out.a_data; 256 error = vm_map_find(&vmspace->vm_map, 257 NULL, 258 0, 259 &vmaddr, 260 gz->bss_size, 261 FALSE, VM_PROT_ALL, VM_PROT_ALL, 0); 262 if (error) { 263 gz->where = __LINE__; 264 return (error); 265 } 266 } 267 /* Fill in process VM information */ 268 vmspace->vm_tsize = gz->a_out.a_text >> PAGE_SHIFT; 269 vmspace->vm_dsize = (gz->a_out.a_data + gz->bss_size) >> PAGE_SHIFT; 270 vmspace->vm_taddr = (caddr_t) (uintptr_t) gz->virtual_offset; 271 vmspace->vm_daddr = (caddr_t) (uintptr_t) 272 (gz->virtual_offset + gz->a_out.a_text); 273 274 /* Fill in image_params */ 275 gz->ip->interpreted = 0; 276 gz->ip->entry_addr = gz->a_out.a_entry; 277 278 gz->ip->proc->p_sysent = &aout_sysvec; 279 280 return 0; 281 } 282 283 static int 284 NextByte(void *vp) 285 { 286 int error; 287 struct imgact_gzip *igz = (struct imgact_gzip *) vp; 288 289 if (igz->idx >= igz->len) { 290 igz->where = __LINE__; 291 return GZ_EOF; 292 } 293 if (igz->inbuf && igz->idx < (igz->offset + PAGE_SIZE)) { 294 return igz->inbuf[(igz->idx++) - igz->offset]; 295 } 296 if (igz->inbuf) { 297 error = vm_map_remove(kernel_map, (vm_offset_t) igz->inbuf, 298 (vm_offset_t) igz->inbuf + PAGE_SIZE); 299 if (error) { 300 igz->where = __LINE__; 301 igz->error = error; 302 return GZ_EOF; 303 } 304 } 305 igz->offset = igz->idx & ~PAGE_MASK; 306 307 error = vm_mmap(kernel_map, /* map */ 308 (vm_offset_t *) & igz->inbuf, /* address */ 309 PAGE_SIZE, /* size */ 310 VM_PROT_READ, /* protection */ 311 VM_PROT_READ, /* max protection */ 312 0, /* flags */ 313 (caddr_t) igz->ip->vp, /* vnode */ 314 igz->offset); /* offset */ 315 if (error) { 316 igz->where = __LINE__; 317 igz->error = error; 318 return GZ_EOF; 319 } 320 return igz->inbuf[(igz->idx++) - igz->offset]; 321 } 322 323 static int 324 Flush(void *vp, u_char * ptr, u_long siz) 325 { 326 struct imgact_gzip *gz = (struct imgact_gzip *) vp; 327 u_char *p = ptr, *q; 328 int i; 329 330 /* First, find a a.out-header */ 331 if (gz->output < sizeof gz->a_out) { 332 q = (u_char *) & gz->a_out; 333 i = min(siz, sizeof gz->a_out - gz->output); 334 bcopy(p, q + gz->output, i); 335 gz->output += i; 336 p += i; 337 siz -= i; 338 if (gz->output == sizeof gz->a_out) { 339 gz->gotheader = 1; 340 i = do_aout_hdr(gz); 341 if (i == -1) { 342 if (!gz->where) 343 gz->where = __LINE__; 344 gz->error = ENOEXEC; 345 return ENOEXEC; 346 } else if (i) { 347 gz->where = __LINE__; 348 gz->error = i; 349 return ENOEXEC; 350 } 351 if (gz->file_offset == 0) { 352 q = (u_char *) (uintptr_t) gz->virtual_offset; 353 copyout(&gz->a_out, q, sizeof gz->a_out); 354 } 355 } 356 } 357 /* Skip over zero-padded first PAGE if needed */ 358 if (gz->output < gz->file_offset && 359 gz->output + siz > gz->file_offset) { 360 i = min(siz, gz->file_offset - gz->output); 361 gz->output += i; 362 p += i; 363 siz -= i; 364 } 365 if (gz->output >= gz->file_offset && gz->output < gz->file_end) { 366 i = min(siz, gz->file_end - gz->output); 367 q = (u_char *) (uintptr_t) 368 (gz->virtual_offset + gz->output - gz->file_offset); 369 copyout(p, q, i); 370 gz->output += i; 371 p += i; 372 siz -= i; 373 } 374 gz->output += siz; 375 return 0; 376 } 377 378 379 /* 380 * Tell kern_execve.c about it, with a little help from the linker. 381 */ 382 static struct execsw gzip_execsw = {exec_gzip_imgact, "gzip"}; 383 EXEC_SET(execgzip, gzip_execsw);
Cache object: 62554370984f4625fbf92284f4745902
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