1 /* This file handles the EXEC system call. It performs the work as follows: 2 * - see if the permissions allow the file to be executed 3 * - read the header and extract the sizes 4 * - fetch the initial args and environment from the user space 5 * - allocate the memory for the new process 6 * - copy the initial stack from PM to the process 7 * - read in the text and data segments and copy to the process 8 * - take care of setuid and setgid bits 9 * - fix up 'mproc' table 10 * - tell kernel about EXEC 11 * - save offset to initial argc (for ps) 12 * 13 * The entry points into this file are: 14 * pm_exec: perform the EXEC system call 15 */ 16 17 #include "fs.h" 18 #include <sys/stat.h> 19 #include <sys/mman.h> 20 #include <minix/callnr.h> 21 #include <minix/endpoint.h> 22 #include <minix/com.h> 23 #include <minix/u64.h> 24 #include <signal.h> 25 #include <stdlib.h> 26 #include <string.h> 27 #include <sys/dirent.h> 28 #include <sys/exec.h> 29 #include <sys/param.h> 30 #include "path.h" 31 #include "vnode.h" 32 #include "file.h" 33 #include <minix/vfsif.h> 34 #include <machine/vmparam.h> 35 #include <assert.h> 36 #include <fcntl.h> 37 38 #define _KERNEL /* for ELF_AUX_ENTRIES */ 39 #include <libexec.h> 40 41 /* fields only used by elf and in VFS */ 42 struct vfs_exec_info { 43 struct exec_info args; /* libexec exec args */ 44 struct vnode *vp; /* Exec file's vnode */ 45 struct vmnt *vmp; /* Exec file's vmnt */ 46 struct stat sb; /* Exec file's stat structure */ 47 int userflags; /* exec() flags from userland */ 48 int is_dyn; /* Dynamically linked executable */ 49 int elf_main_fd; /* Dyn: FD of main program execuatble */ 50 char execname[PATH_MAX]; /* Full executable invocation */ 51 int vmfd; 52 int vmfd_used; 53 }; 54 55 static int patch_stack(struct vnode *vp, char stack[ARG_MAX], 56 size_t *stk_bytes, char path[PATH_MAX], vir_bytes *vsp); 57 static int is_script(struct vfs_exec_info *execi); 58 static int insert_arg(char stack[ARG_MAX], size_t *stk_bytes, char *arg, 59 vir_bytes *vsp, char replace); 60 static void clo_exec(struct fproc *rfp); 61 static int stack_prepare_elf(struct vfs_exec_info *execi, 62 char *curstack, size_t *frame_len, vir_bytes *vsp); 63 static int map_header(struct vfs_exec_info *execi); 64 static int read_seg(struct exec_info *execi, off_t off, vir_bytes seg_addr, size_t seg_bytes); 65 66 #define PTRSIZE sizeof(char *) /* Size of pointers in argv[] and envp[]. */ 67 68 /* Array of loaders for different object file formats */ 69 typedef int (*exechook_t)(struct vfs_exec_info *execpackage); 70 typedef int (*stackhook_t)(struct vfs_exec_info *execi, char *curstack, 71 size_t *frame_len, vir_bytes *vsp); 72 struct exec_loaders { 73 libexec_exec_loadfunc_t load_object; /* load executable into memory */ 74 stackhook_t setup_stack; /* prepare stack before argc and argv push */ 75 }; 76 77 static const struct exec_loaders exec_loaders[] = { 78 { libexec_load_elf, stack_prepare_elf }, 79 { NULL, NULL } 80 }; 81 82 #define lock_exec() lock_proc(fproc_addr(VM_PROC_NR)) 83 #define unlock_exec() unlock_proc(fproc_addr(VM_PROC_NR)) 84 85 /*===========================================================================* 86 * get_read_vp * 87 *===========================================================================*/ 88 static int get_read_vp(struct vfs_exec_info *execi, 89 char *fullpath, int copyprogname, int sugid, struct lookup *resolve, struct fproc *fp) 90 { 91 /* Make the executable that we want to exec() into the binary pointed 92 * to by 'fullpath.' This function fills in necessary details in the execi 93 * structure, such as opened vnode. It unlocks and releases the vnode if 94 * it was already there. This makes it easy to change the executable 95 * during the exec(), which is often necessary, by calling this function 96 * more than once. This is specifically necessary when we discover the 97 * executable is actually a script or a dynamically linked executable. 98 */ 99 int r; 100 101 /* Caller wants to switch vp to the file in 'fullpath.' 102 * unlock and put it first if there is any there. 103 */ 104 if(execi->vp) { 105 unlock_vnode(execi->vp); 106 put_vnode(execi->vp); 107 execi->vp = NULL; 108 } 109 110 /* Remember/overwrite the executable name if requested. */ 111 if(copyprogname) { 112 char *cp = strrchr(fullpath, '/'); 113 if(cp) cp++; 114 else cp = fullpath; 115 strlcpy(execi->args.progname, cp, sizeof(execi->args.progname)); 116 execi->args.progname[sizeof(execi->args.progname)-1] = '\0'; 117 } 118 119 /* Open executable */ 120 if ((execi->vp = eat_path(resolve, fp)) == NULL) 121 return err_code; 122 123 unlock_vmnt(execi->vmp); 124 125 if (!S_ISREG(execi->vp->v_mode)) 126 return ENOEXEC; 127 else if ((r = forbidden(fp, execi->vp, X_BIT)) != OK) 128 return r; 129 else 130 r = req_stat(execi->vp->v_fs_e, execi->vp->v_inode_nr, 131 VFS_PROC_NR, (vir_bytes) &(execi->sb)); 132 133 if (r != OK) return r; 134 135 /* If caller wants us to, honour suid/guid mode bits. */ 136 if (sugid) { 137 /* Deal with setuid/setgid executables */ 138 if (execi->vp->v_mode & I_SET_UID_BIT) { 139 execi->args.new_uid = execi->vp->v_uid; 140 execi->args.allow_setuid = 1; 141 } 142 if (execi->vp->v_mode & I_SET_GID_BIT) { 143 execi->args.new_gid = execi->vp->v_gid; 144 execi->args.allow_setuid = 1; 145 } 146 } 147 148 /* Read in first chunk of file. */ 149 if((r=map_header(execi)) != OK) 150 return r; 151 152 return OK; 153 } 154 155 #define FAILCHECK(expr) if((r=(expr)) != OK) { goto pm_execfinal; } while(0) 156 #define Get_read_vp(e,f,p,s,rs,fp) do { \ 157 r=get_read_vp(&e,f,p,s,rs,fp); if(r != OK) { FAILCHECK(r); } \ 158 } while(0) 159 160 static int vfs_memmap(struct exec_info *execi, 161 vir_bytes vaddr, vir_bytes len, vir_bytes foffset, u16_t clearend, 162 int protflags) 163 { 164 struct vfs_exec_info *vi = (struct vfs_exec_info *) execi->opaque; 165 struct vnode *vp = ((struct vfs_exec_info *) execi->opaque)->vp; 166 int r; 167 u16_t flags = 0; 168 169 if(protflags & PROT_WRITE) 170 flags |= MVM_WRITABLE; 171 172 r = minix_vfs_mmap(execi->proc_e, foffset, len, 173 vp->v_dev, vp->v_inode_nr, vi->vmfd, vaddr, clearend, flags); 174 if(r == OK) { 175 vi->vmfd_used = 1; 176 } 177 178 return r; 179 } 180 181 /*===========================================================================* 182 * pm_exec * 183 *===========================================================================*/ 184 int pm_exec(vir_bytes path, size_t path_len, vir_bytes frame, size_t frame_len, 185 vir_bytes *pc, vir_bytes *newsp, vir_bytes *UNUSED(ps_str)) 186 { 187 /* Perform the execve(name, argv, envp) call. The user library builds a 188 * complete stack image, including pointers, args, environ, etc. The stack 189 * is copied to a buffer inside VFS, and then to the new core image. 190 * 191 * ps_str is not currently used, but may be if the ps_strings structure has to 192 * be moved to another location. 193 */ 194 int r; 195 vir_bytes vsp; 196 static char mbuf[ARG_MAX]; /* buffer for stack and zeroes */ 197 struct vfs_exec_info execi; 198 int i; 199 static char fullpath[PATH_MAX], 200 elf_interpreter[PATH_MAX], 201 firstexec[PATH_MAX], 202 finalexec[PATH_MAX]; 203 struct lookup resolve; 204 struct fproc *vmfp = fproc_addr(VM_PROC_NR); 205 stackhook_t makestack = NULL; 206 struct filp *newfilp = NULL; 207 208 lock_exec(); 209 210 /* unset execi values are 0. */ 211 memset(&execi, 0, sizeof(execi)); 212 execi.vmfd = -1; 213 214 /* passed from exec() libc code */ 215 execi.userflags = 0; 216 execi.args.stack_high = kinfo.user_sp; 217 execi.args.stack_size = DEFAULT_STACK_LIMIT; 218 219 fp->text_size = 0; 220 fp->data_size = 0; 221 222 lookup_init(&resolve, fullpath, PATH_NOFLAGS, &execi.vmp, &execi.vp); 223 224 resolve.l_vmnt_lock = VMNT_READ; 225 resolve.l_vnode_lock = VNODE_READ; 226 227 /* Fetch the stack from the user before destroying the old core image. */ 228 if (frame_len > ARG_MAX) 229 FAILCHECK(ENOMEM); /* stack too big */ 230 231 r = sys_datacopy_wrapper(fp->fp_endpoint, (vir_bytes) frame, SELF, (vir_bytes) mbuf, 232 (size_t) frame_len); 233 if (r != OK) { /* can't fetch stack (e.g. bad virtual addr) */ 234 printf("VFS: pm_exec: sys_datacopy failed\n"); 235 FAILCHECK(r); 236 } 237 238 /* Compute the current virtual stack pointer, has to be done before calling 239 * patch_stack, which needs it, and will adapt as required. */ 240 vsp = execi.args.stack_high - frame_len; 241 242 /* The default is to keep the original user and group IDs */ 243 execi.args.new_uid = fp->fp_effuid; 244 execi.args.new_gid = fp->fp_effgid; 245 246 /* Get the exec file name. */ 247 FAILCHECK(fetch_name(path, path_len, fullpath)); 248 strlcpy(finalexec, fullpath, PATH_MAX); 249 strlcpy(firstexec, fullpath, PATH_MAX); 250 251 /* Get_read_vp will return an opened vn in execi. 252 * if necessary it releases the existing vp so we can 253 * switch after we find out what's inside the file. 254 * It reads the start of the file. 255 */ 256 Get_read_vp(execi, fullpath, 1, 1, &resolve, fp); 257 258 /* If this is a script (i.e. has a #!/interpreter line), 259 * retrieve the name of the interpreter and open that 260 * executable instead. 261 */ 262 if(is_script(&execi)) { 263 /* patch_stack will add interpreter name and 264 * args to stack and retrieve the new binary 265 * name into fullpath. 266 */ 267 FAILCHECK(fetch_name(path, path_len, fullpath)); 268 FAILCHECK(patch_stack(execi.vp, mbuf, &frame_len, fullpath, &vsp)); 269 270 strlcpy(finalexec, fullpath, PATH_MAX); 271 strlcpy(firstexec, fullpath, PATH_MAX); 272 Get_read_vp(execi, fullpath, 1, 0, &resolve, fp); 273 } 274 275 /* If this is a dynamically linked executable, retrieve 276 * the name of that interpreter in elf_interpreter and open that 277 * executable instead. But open the current executable in an 278 * fd for the current process. 279 */ 280 if(elf_has_interpreter(execi.args.hdr, execi.args.hdr_len, 281 elf_interpreter, sizeof(elf_interpreter))) { 282 /* Switch the executable vnode to the interpreter */ 283 execi.is_dyn = 1; 284 285 /* The interpreter (loader) needs an fd to the main program, 286 * which is currently in finalexec 287 */ 288 if((r = execi.elf_main_fd = common_open(finalexec, O_RDONLY, 0)) < 0) { 289 printf("VFS: exec: dynamic: open main exec failed %s (%d)\n", 290 fullpath, r); 291 FAILCHECK(r); 292 } 293 294 /* ld.so is linked at 0, but it can relocate itself; we 295 * want it higher to trap NULL pointer dereferences. 296 * Let's put it below the stack, and reserve 10MB for ld.so. 297 */ 298 execi.args.load_offset = 299 execi.args.stack_high - execi.args.stack_size - 0xa00000; 300 301 /* Remember it */ 302 strlcpy(execi.execname, finalexec, PATH_MAX); 303 304 /* The executable we need to execute first (loader) 305 * is in elf_interpreter, and has to be in fullpath to 306 * be looked up 307 */ 308 strlcpy(fullpath, elf_interpreter, PATH_MAX); 309 strlcpy(firstexec, elf_interpreter, PATH_MAX); 310 Get_read_vp(execi, fullpath, 0, 0, &resolve, fp); 311 } 312 313 /* We also want an FD for VM to mmap() the process in if possible. */ 314 { 315 struct vnode *vp = execi.vp; 316 assert(vp); 317 if ((vp->v_vmnt->m_fs_flags & RES_HASPEEK) && 318 major(vp->v_dev) != MEMORY_MAJOR) { 319 int newfd = -1; 320 if(get_fd(vmfp, 0, R_BIT, &newfd, &newfilp) == OK) { 321 assert(newfd >= 0 && newfd < OPEN_MAX); 322 assert(!vmfp->fp_filp[newfd]); 323 newfilp->filp_count = 1; 324 newfilp->filp_vno = vp; 325 newfilp->filp_flags = O_RDONLY; 326 vmfp->fp_filp[newfd] = newfilp; 327 /* dup_vnode(vp); */ 328 execi.vmfd = newfd; 329 execi.args.memmap = vfs_memmap; 330 } 331 } 332 } 333 334 /* callback functions and data */ 335 execi.args.copymem = read_seg; 336 execi.args.clearproc = libexec_clearproc_vm_procctl; 337 execi.args.clearmem = libexec_clear_sys_memset; 338 execi.args.allocmem_prealloc_cleared = libexec_alloc_mmap_prealloc_cleared; 339 execi.args.allocmem_prealloc_junk = libexec_alloc_mmap_prealloc_junk; 340 execi.args.allocmem_ondemand = libexec_alloc_mmap_ondemand; 341 execi.args.opaque = &execi; 342 343 execi.args.proc_e = fp->fp_endpoint; 344 execi.args.frame_len = frame_len; 345 execi.args.filesize = execi.vp->v_size; 346 347 for (i = 0; exec_loaders[i].load_object != NULL; i++) { 348 r = (*exec_loaders[i].load_object)(&execi.args); 349 /* Loaded successfully, so no need to try other loaders */ 350 if (r == OK) { makestack = exec_loaders[i].setup_stack; break; } 351 } 352 353 FAILCHECK(r); 354 355 /* Inform PM */ 356 FAILCHECK(libexec_pm_newexec(fp->fp_endpoint, &execi.args)); 357 358 /* Save off PC */ 359 *pc = execi.args.pc; 360 361 /* call a stack-setup function if this executable type wants it */ 362 if(makestack) FAILCHECK(makestack(&execi, mbuf, &frame_len, &vsp)); 363 364 /* Copy the stack from VFS to new core image. */ 365 FAILCHECK(sys_datacopy_wrapper(SELF, (vir_bytes) mbuf, fp->fp_endpoint, 366 (vir_bytes) vsp, (phys_bytes)frame_len)); 367 368 /* Return new stack pointer to caller */ 369 *newsp = vsp; 370 371 clo_exec(fp); 372 373 if (execi.args.allow_setuid) { 374 /* If after loading the image we're still allowed to run with 375 * setuid or setgid, change credentials now */ 376 fp->fp_effuid = execi.args.new_uid; 377 fp->fp_effgid = execi.args.new_gid; 378 } 379 380 /* Remember the new name of the process */ 381 strlcpy(fp->fp_name, execi.args.progname, PROC_NAME_LEN); 382 fp->text_size = execi.args.text_size; 383 fp->data_size = execi.args.data_size; 384 385 pm_execfinal: 386 if(newfilp) unlock_filp(newfilp); 387 else if (execi.vp != NULL) { 388 unlock_vnode(execi.vp); 389 put_vnode(execi.vp); 390 } 391 392 if(execi.vmfd >= 0 && !execi.vmfd_used) { 393 if(OK != close_fd(vmfp, execi.vmfd)) { 394 printf("VFS: unexpected close fail of vm fd\n"); 395 } 396 } 397 398 unlock_exec(); 399 400 return(r); 401 } 402 403 /* This is a copy-paste of the same macro in minix/lib/libc/sys/stack_utils.c. 404 * Keep it synchronized. */ 405 #define STACK_MIN_SZ \ 406 ( \ 407 sizeof(int) + sizeof(void *) * 2 + \ 408 sizeof(AuxInfo) * PMEF_AUXVECTORS + PMEF_EXECNAMELEN1 + \ 409 sizeof(struct ps_strings) \ 410 ) 411 412 static int stack_prepare_elf(struct vfs_exec_info *execi, char *frame, size_t *frame_size, 413 vir_bytes *vsp) 414 { 415 AuxInfo *aux_vec, *aux_vec_end; 416 vir_bytes vap; /* Address in proc space of the first AuxVec. */ 417 Elf_Ehdr const * const elf_header = (Elf_Ehdr *) execi->args.hdr; 418 struct ps_strings const * const psp = (struct ps_strings *) 419 (frame + (*frame_size - sizeof(struct ps_strings))); 420 421 size_t const execname_len = strlen(execi->execname); 422 423 if (!execi->is_dyn) 424 return OK; 425 426 if (execi->args.hdr_len < sizeof(*elf_header)) { 427 printf("VFS: malformed ELF headers for exec\n"); 428 return ENOEXEC; 429 } 430 431 if (*frame_size < STACK_MIN_SZ) { 432 printf("VFS: malformed stack for exec(), smaller than minimum" 433 " possible size.\n"); 434 return ENOEXEC; 435 } 436 437 /* Find first Aux vector in the stack frame. */ 438 vap = (vir_bytes)(psp->ps_envstr + (psp->ps_nenvstr + 1)); 439 aux_vec = (AuxInfo *) (frame + (vap - *vsp)); 440 aux_vec_end = aux_vec + PMEF_AUXVECTORS; 441 442 if (((char *)aux_vec < frame) || 443 ((char *)aux_vec > (frame + *frame_size))) { 444 printf("VFS: malformed stack for exec(), first AuxVector is" 445 " not on the stack.\n"); 446 return ENOEXEC; 447 } 448 449 if (((char *)aux_vec_end < frame) || 450 ((char *)aux_vec_end > (frame + *frame_size))) { 451 printf("VFS: malformed stack for exec(), last AuxVector is" 452 " not on the stack.\n"); 453 return ENOEXEC; 454 } 455 456 /* Userland provides a fully filled stack frame, with argc, argv, envp 457 * and then all the argv and envp strings; consistent with ELF ABI, 458 * except for a list of Aux vectors that should be between envp points 459 * and the start of the strings. 460 * 461 * It would take some very unpleasant hackery to insert the aux vectors 462 * before the strings, and correct all the pointers, so the exec code 463 * in libc makes space for us. 464 */ 465 466 #define AUXINFO(a, type, value) \ 467 do { \ 468 if (a < aux_vec_end) { \ 469 a->a_type = type; \ 470 a->a_v = value; \ 471 a++; \ 472 } else { \ 473 printf("VFS: No more room for ELF AuxVec type %d, skipping it for %s\n", type, execi->execname); \ 474 (aux_vec_end - 1)->a_type = AT_NULL; \ 475 (aux_vec_end - 1)->a_v = 0; \ 476 } \ 477 } while(0) 478 479 AUXINFO(aux_vec, AT_BASE, execi->args.load_base); 480 AUXINFO(aux_vec, AT_ENTRY, execi->args.pc); 481 AUXINFO(aux_vec, AT_EXECFD, execi->elf_main_fd); 482 #if 0 483 AUXINFO(aux_vec, AT_PHDR, XXX ); /* should be &phdr[0] */ 484 AUXINFO(aux_vec, AT_PHENT, elf_header->e_phentsize); 485 AUXINFO(aux_vec, AT_PHNUM, elf_header->e_phnum); 486 487 AUXINFO(aux_vec, AT_RUID, XXX); 488 AUXINFO(aux_vec, AT_RGID, XXX); 489 #endif 490 AUXINFO(aux_vec, AT_EUID, execi->args.new_uid); 491 AUXINFO(aux_vec, AT_EGID, execi->args.new_gid); 492 AUXINFO(aux_vec, AT_PAGESZ, PAGE_SIZE); 493 494 if(execname_len < PMEF_EXECNAMELEN1) { 495 char *spacestart; 496 vir_bytes userp; 497 498 /* Empty space starts after aux_vec table; we can put the name 499 * here. */ 500 spacestart = (char *) aux_vec + 2 * sizeof(AuxInfo); 501 strlcpy(spacestart, execi->execname, PMEF_EXECNAMELEN1); 502 memset(spacestart + execname_len, '\0', 503 PMEF_EXECNAMELEN1 - execname_len); 504 505 /* What will the address of the string for the user be */ 506 userp = *vsp + (spacestart - frame); 507 508 /* Move back to where the AT_NULL is */ 509 AUXINFO(aux_vec, AT_SUN_EXECNAME, userp); 510 } 511 512 /* Always terminate with AT_NULL */ 513 AUXINFO(aux_vec, AT_NULL, 0); 514 515 return OK; 516 } 517 518 /*===========================================================================* 519 * is_script * 520 *===========================================================================*/ 521 static int is_script(struct vfs_exec_info *execi) 522 { 523 /* Is Interpreted script? */ 524 assert(execi->args.hdr != NULL); 525 526 return(execi->args.hdr[0] == '#' && execi->args.hdr[1] == '!' 527 && execi->args.hdr_len >= 2); 528 } 529 530 /*===========================================================================* 531 * patch_stack * 532 *===========================================================================*/ 533 static int patch_stack(vp, stack, stk_bytes, path, vsp) 534 struct vnode *vp; /* pointer for open script file */ 535 char stack[ARG_MAX]; /* pointer to stack image within VFS */ 536 size_t *stk_bytes; /* size of initial stack */ 537 char path[PATH_MAX]; /* path to script file */ 538 vir_bytes *vsp; 539 { 540 /* Patch the argument vector to include the path name of the script to be 541 * interpreted, and all strings on the #! line. Returns the path name of 542 * the interpreter. 543 */ 544 enum { INSERT=FALSE, REPLACE=TRUE }; 545 int n, r; 546 off_t pos, new_pos; 547 char *sp, *interp = NULL; 548 size_t cum_io; 549 char buf[PAGE_SIZE]; 550 551 /* Make 'path' the new argv[0]. */ 552 if (!insert_arg(stack, stk_bytes, path, vsp, REPLACE)) return(ENOMEM); 553 554 pos = 0; /* Read from the start of the file */ 555 556 /* Issue request */ 557 r = req_readwrite(vp->v_fs_e, vp->v_inode_nr, pos, READING, VFS_PROC_NR, 558 (vir_bytes) buf, sizeof(buf), &new_pos, &cum_io); 559 560 if (r != OK) return(r); 561 562 n = vp->v_size; 563 if (n > sizeof(buf)) 564 n = sizeof(buf); 565 if (n < 2) return ENOEXEC; 566 567 sp = &(buf[2]); /* just behind the #! */ 568 n -= 2; 569 if (n > PATH_MAX) n = PATH_MAX; 570 571 /* Use the 'path' variable for temporary storage */ 572 memcpy(path, sp, n); 573 574 if ((sp = memchr(path, '\n', n)) == NULL) /* must be a proper line */ 575 return(ENOEXEC); 576 577 /* Move sp backwards through script[], prepending each string to stack. */ 578 for (;;) { 579 /* skip spaces behind argument. */ 580 while (sp > path && (*--sp == ' ' || *sp == '\t')) {} 581 if (sp == path) break; 582 583 sp[1] = 0; 584 /* Move to the start of the argument. */ 585 while (sp > path && sp[-1] != ' ' && sp[-1] != '\t') --sp; 586 587 interp = sp; 588 if (!insert_arg(stack, stk_bytes, sp, vsp, INSERT)) { 589 printf("VFS: patch_stack: insert_arg failed\n"); 590 return(ENOMEM); 591 } 592 } 593 594 if(!interp) 595 return ENOEXEC; 596 597 if (interp != path) 598 memmove(path, interp, strlen(interp)+1); 599 600 return(OK); 601 } 602 603 /*===========================================================================* 604 * insert_arg * 605 *===========================================================================*/ 606 static int insert_arg(char stack[ARG_MAX], size_t *stk_bytes, char *arg, 607 vir_bytes *vsp, char replace) 608 { 609 /* Patch the stack so that arg will become argv[0]. Be careful, the 610 * stack may be filled with garbage, although it normally looks like 611 * this: 612 * nargs argv[0] ... argv[nargs-1] NULL envp[0] ... NULL 613 * followed by the strings "pointed" to by the argv[i] and the envp[i]. 614 * The * pointers are in the new process address space. 615 * 616 * Return true iff the operation succeeded. 617 */ 618 struct ps_strings *psp; 619 int offset; 620 size_t old_bytes = *stk_bytes; 621 622 int const arg_len = strlen(arg) + 1; 623 624 /* Offset to argv[0][0] in the stack frame. */ 625 int const a0 = (int)(((char **)stack)[1] - *vsp); 626 627 /* Check that argv[0] points within the stack frame. */ 628 if ((a0 < 0) || (a0 >= old_bytes)) { 629 printf("vfs:: argv[0][] not within stack range!! %i\n", a0); 630 return FALSE; 631 } 632 633 if (!replace) { 634 /* Prepending arg adds one pointer, one string and a zero byte. */ 635 offset = arg_len + PTRSIZE; 636 } else { 637 /* replacing argv[0] with arg adds the difference in length of 638 * the two strings. Make sure we don't go beyond the stack size 639 * when computing the length of the current argv[0]. */ 640 offset = arg_len - strnlen(stack + a0, ARG_MAX - a0 - 1); 641 } 642 643 /* As ps_strings follows the strings, ensure the offset is word aligned. */ 644 offset = offset + (PTRSIZE - ((PTRSIZE + offset) % PTRSIZE)); 645 646 /* The stack will grow (or shrink) by offset bytes. */ 647 if ((*stk_bytes += offset) > ARG_MAX) { 648 printf("vfs:: offset too big!! %zu (max %d)\n", *stk_bytes, 649 ARG_MAX); 650 return FALSE; 651 } 652 653 /* Reposition the strings by offset bytes */ 654 memmove(stack + a0 + offset, stack + a0, old_bytes - a0); 655 656 /* Put arg in the new space, leaving padding in front of it. */ 657 strlcpy(stack + a0 + offset - arg_len, arg, arg_len); 658 659 if (!replace) { 660 /* Make space for a new argv[0]. */ 661 memmove(stack + 2 * PTRSIZE, 662 stack + 1 * PTRSIZE, a0 - 2 * PTRSIZE); 663 664 ((char **) stack)[0]++; /* nargs++; */ 665 } 666 667 /* set argv[0] correctly */ 668 ((char **) stack)[1] = (char *) a0 - arg_len + *vsp; 669 670 /* Update stack pointer in the process address space. */ 671 *vsp -= offset; 672 673 /* Update argv and envp in ps_strings */ 674 psp = (struct ps_strings *) (stack + *stk_bytes - sizeof(struct ps_strings)); 675 psp->ps_argvstr -= (offset / PTRSIZE); 676 if (!replace) { 677 psp->ps_nargvstr++; 678 } 679 psp->ps_envstr = psp->ps_argvstr + psp->ps_nargvstr + 1; 680 681 return TRUE; 682 } 683 684 /*===========================================================================* 685 * read_seg * 686 *===========================================================================*/ 687 static int read_seg(struct exec_info *execi, off_t off, vir_bytes seg_addr, size_t seg_bytes) 688 { 689 /* 690 * The byte count on read is usually smaller than the segment count, because 691 * a segment is padded out to a click multiple, and the data segment is only 692 * partially initialized. 693 */ 694 int r; 695 off_t new_pos; 696 size_t cum_io; 697 struct vnode *vp = ((struct vfs_exec_info *) execi->opaque)->vp; 698 699 /* Make sure that the file is big enough */ 700 if (off + seg_bytes > LONG_MAX) return(EIO); 701 if ((unsigned long) vp->v_size < off+seg_bytes) return(EIO); 702 703 if ((r = req_readwrite(vp->v_fs_e, vp->v_inode_nr, off, READING, 704 execi->proc_e, (vir_bytes) seg_addr, seg_bytes, 705 &new_pos, &cum_io)) != OK) { 706 printf("VFS: read_seg: req_readwrite failed (data)\n"); 707 return(r); 708 } 709 710 if (r == OK && cum_io != seg_bytes) 711 printf("VFS: read_seg segment has not been read properly\n"); 712 713 return(r); 714 } 715 716 717 /*===========================================================================* 718 * clo_exec * 719 *===========================================================================*/ 720 static void clo_exec(struct fproc *rfp) 721 { 722 /* Files can be marked with the FD_CLOEXEC bit (in fp->fp_cloexec). 723 */ 724 int i; 725 726 /* Check the file desriptors one by one for presence of FD_CLOEXEC. */ 727 for (i = 0; i < OPEN_MAX; i++) 728 if ( FD_ISSET(i, &rfp->fp_cloexec_set)) 729 (void) close_fd(rfp, i); 730 } 731 732 /*===========================================================================* 733 * map_header * 734 *===========================================================================*/ 735 static int map_header(struct vfs_exec_info *execi) 736 { 737 int r; 738 size_t cum_io; 739 off_t pos, new_pos; 740 static char hdr[PAGE_SIZE]; /* Assume that header is not larger than a page */ 741 742 pos = 0; /* Read from the start of the file */ 743 744 /* How much is sensible to read */ 745 execi->args.hdr_len = MIN(execi->vp->v_size, sizeof(hdr)); 746 execi->args.hdr = hdr; 747 748 r = req_readwrite(execi->vp->v_fs_e, execi->vp->v_inode_nr, 749 pos, READING, VFS_PROC_NR, (vir_bytes) hdr, 750 execi->args.hdr_len, &new_pos, &cum_io); 751 if (r != OK) { 752 printf("VFS: exec: map_header: req_readwrite failed\n"); 753 return(r); 754 } 755 756 return(OK); 757 } 758