| 1 | /* |
| 2 | * linux/fs/exec.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | /* |
| 8 | * #!-checking implemented by tytso. |
| 9 | */ |
| 10 | /* |
| 11 | * Demand-loading implemented 01.12.91 - no need to read anything but |
| 12 | * the header into memory. The inode of the executable is put into |
| 13 | * "current->executable", and page faults do the actual loading. Clean. |
| 14 | * |
| 15 | * Once more I can proudly say that linux stood up to being changed: it |
| 16 | * was less than 2 hours work to get demand-loading completely implemented. |
| 17 | * |
| 18 | * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead, |
| 19 | * current->executable is only used by the procfs. This allows a dispatch |
| 20 | * table to check for several different types of binary formats. We keep |
| 21 | * trying until we recognize the file or we run out of supported binary |
| 22 | * formats. |
| 23 | */ |
| 24 | |
| 25 | #include <linux/slab.h> |
| 26 | #include <linux/file.h> |
| 27 | #include <linux/fdtable.h> |
| 28 | #include <linux/mm.h> |
| 29 | #include <linux/stat.h> |
| 30 | #include <linux/fcntl.h> |
| 31 | #include <linux/swap.h> |
| 32 | #include <linux/string.h> |
| 33 | #include <linux/init.h> |
| 34 | #include <linux/pagemap.h> |
| 35 | #include <linux/perf_event.h> |
| 36 | #include <linux/highmem.h> |
| 37 | #include <linux/spinlock.h> |
| 38 | #include <linux/key.h> |
| 39 | #include <linux/personality.h> |
| 40 | #include <linux/binfmts.h> |
| 41 | #include <linux/utsname.h> |
| 42 | #include <linux/pid_namespace.h> |
| 43 | #include <linux/module.h> |
| 44 | #include <linux/namei.h> |
| 45 | #include <linux/proc_fs.h> |
| 46 | #include <linux/mount.h> |
| 47 | #include <linux/security.h> |
| 48 | #include <linux/syscalls.h> |
| 49 | #include <linux/tsacct_kern.h> |
| 50 | #include <linux/cn_proc.h> |
| 51 | #include <linux/audit.h> |
| 52 | #include <linux/tracehook.h> |
| 53 | #include <linux/kmod.h> |
| 54 | #include <linux/fsnotify.h> |
| 55 | #include <linux/fs_struct.h> |
| 56 | #include <linux/pipe_fs_i.h> |
| 57 | #include <linux/oom.h> |
| 58 | |
| 59 | #include <asm/uaccess.h> |
| 60 | #include <asm/mmu_context.h> |
| 61 | #include <asm/tlb.h> |
| 62 | #include "internal.h" |
| 63 | |
| 64 | int core_uses_pid; |
| 65 | char core_pattern[CORENAME_MAX_SIZE] = "core"; |
| 66 | unsigned int core_pipe_limit; |
| 67 | int suid_dumpable = 0; |
| 68 | |
| 69 | struct core_name { |
| 70 | char *corename; |
| 71 | int used, size; |
| 72 | }; |
| 73 | static atomic_t call_count = ATOMIC_INIT(1); |
| 74 | |
| 75 | /* The maximal length of core_pattern is also specified in sysctl.c */ |
| 76 | |
| 77 | static LIST_HEAD(formats); |
| 78 | static DEFINE_RWLOCK(binfmt_lock); |
| 79 | |
| 80 | int __register_binfmt(struct linux_binfmt * fmt, int insert) |
| 81 | { |
| 82 | if (!fmt) |
| 83 | return -EINVAL; |
| 84 | write_lock(&binfmt_lock); |
| 85 | insert ? list_add(&fmt->lh, &formats) : |
| 86 | list_add_tail(&fmt->lh, &formats); |
| 87 | write_unlock(&binfmt_lock); |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | EXPORT_SYMBOL(__register_binfmt); |
| 92 | |
| 93 | void unregister_binfmt(struct linux_binfmt * fmt) |
| 94 | { |
| 95 | write_lock(&binfmt_lock); |
| 96 | list_del(&fmt->lh); |
| 97 | write_unlock(&binfmt_lock); |
| 98 | } |
| 99 | |
| 100 | EXPORT_SYMBOL(unregister_binfmt); |
| 101 | |
| 102 | static inline void put_binfmt(struct linux_binfmt * fmt) |
| 103 | { |
| 104 | module_put(fmt->module); |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * Note that a shared library must be both readable and executable due to |
| 109 | * security reasons. |
| 110 | * |
| 111 | * Also note that we take the address to load from from the file itself. |
| 112 | */ |
| 113 | SYSCALL_DEFINE1(uselib, const char __user *, library) |
| 114 | { |
| 115 | struct file *file; |
| 116 | char *tmp = getname(library); |
| 117 | int error = PTR_ERR(tmp); |
| 118 | static const struct open_flags uselib_flags = { |
| 119 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
| 120 | .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN, |
| 121 | .intent = LOOKUP_OPEN |
| 122 | }; |
| 123 | |
| 124 | if (IS_ERR(tmp)) |
| 125 | goto out; |
| 126 | |
| 127 | file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW); |
| 128 | putname(tmp); |
| 129 | error = PTR_ERR(file); |
| 130 | if (IS_ERR(file)) |
| 131 | goto out; |
| 132 | |
| 133 | error = -EINVAL; |
| 134 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
| 135 | goto exit; |
| 136 | |
| 137 | error = -EACCES; |
| 138 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
| 139 | goto exit; |
| 140 | |
| 141 | fsnotify_open(file); |
| 142 | |
| 143 | error = -ENOEXEC; |
| 144 | if(file->f_op) { |
| 145 | struct linux_binfmt * fmt; |
| 146 | |
| 147 | read_lock(&binfmt_lock); |
| 148 | list_for_each_entry(fmt, &formats, lh) { |
| 149 | if (!fmt->load_shlib) |
| 150 | continue; |
| 151 | if (!try_module_get(fmt->module)) |
| 152 | continue; |
| 153 | read_unlock(&binfmt_lock); |
| 154 | error = fmt->load_shlib(file); |
| 155 | read_lock(&binfmt_lock); |
| 156 | put_binfmt(fmt); |
| 157 | if (error != -ENOEXEC) |
| 158 | break; |
| 159 | } |
| 160 | read_unlock(&binfmt_lock); |
| 161 | } |
| 162 | exit: |
| 163 | fput(file); |
| 164 | out: |
| 165 | return error; |
| 166 | } |
| 167 | |
| 168 | #ifdef CONFIG_MMU |
| 169 | |
| 170 | void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
| 171 | { |
| 172 | struct mm_struct *mm = current->mm; |
| 173 | long diff = (long)(pages - bprm->vma_pages); |
| 174 | |
| 175 | if (!mm || !diff) |
| 176 | return; |
| 177 | |
| 178 | bprm->vma_pages = pages; |
| 179 | |
| 180 | #ifdef SPLIT_RSS_COUNTING |
| 181 | add_mm_counter(mm, MM_ANONPAGES, diff); |
| 182 | #else |
| 183 | spin_lock(&mm->page_table_lock); |
| 184 | add_mm_counter(mm, MM_ANONPAGES, diff); |
| 185 | spin_unlock(&mm->page_table_lock); |
| 186 | #endif |
| 187 | } |
| 188 | |
| 189 | struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| 190 | int write) |
| 191 | { |
| 192 | struct page *page; |
| 193 | int ret; |
| 194 | |
| 195 | #ifdef CONFIG_STACK_GROWSUP |
| 196 | if (write) { |
| 197 | ret = expand_stack_downwards(bprm->vma, pos); |
| 198 | if (ret < 0) |
| 199 | return NULL; |
| 200 | } |
| 201 | #endif |
| 202 | ret = get_user_pages(current, bprm->mm, pos, |
| 203 | 1, write, 1, &page, NULL); |
| 204 | if (ret <= 0) |
| 205 | return NULL; |
| 206 | |
| 207 | if (write) { |
| 208 | unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; |
| 209 | struct rlimit *rlim; |
| 210 | |
| 211 | acct_arg_size(bprm, size / PAGE_SIZE); |
| 212 | |
| 213 | /* |
| 214 | * We've historically supported up to 32 pages (ARG_MAX) |
| 215 | * of argument strings even with small stacks |
| 216 | */ |
| 217 | if (size <= ARG_MAX) |
| 218 | return page; |
| 219 | |
| 220 | /* |
| 221 | * Limit to 1/4-th the stack size for the argv+env strings. |
| 222 | * This ensures that: |
| 223 | * - the remaining binfmt code will not run out of stack space, |
| 224 | * - the program will have a reasonable amount of stack left |
| 225 | * to work from. |
| 226 | */ |
| 227 | rlim = current->signal->rlim; |
| 228 | if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) { |
| 229 | put_page(page); |
| 230 | return NULL; |
| 231 | } |
| 232 | } |
| 233 | |
| 234 | return page; |
| 235 | } |
| 236 | |
| 237 | static void put_arg_page(struct page *page) |
| 238 | { |
| 239 | put_page(page); |
| 240 | } |
| 241 | |
| 242 | static void free_arg_page(struct linux_binprm *bprm, int i) |
| 243 | { |
| 244 | } |
| 245 | |
| 246 | static void free_arg_pages(struct linux_binprm *bprm) |
| 247 | { |
| 248 | } |
| 249 | |
| 250 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| 251 | struct page *page) |
| 252 | { |
| 253 | flush_cache_page(bprm->vma, pos, page_to_pfn(page)); |
| 254 | } |
| 255 | |
| 256 | static int __bprm_mm_init(struct linux_binprm *bprm) |
| 257 | { |
| 258 | int err; |
| 259 | struct vm_area_struct *vma = NULL; |
| 260 | struct mm_struct *mm = bprm->mm; |
| 261 | |
| 262 | bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
| 263 | if (!vma) |
| 264 | return -ENOMEM; |
| 265 | |
| 266 | down_write(&mm->mmap_sem); |
| 267 | vma->vm_mm = mm; |
| 268 | |
| 269 | /* |
| 270 | * Place the stack at the largest stack address the architecture |
| 271 | * supports. Later, we'll move this to an appropriate place. We don't |
| 272 | * use STACK_TOP because that can depend on attributes which aren't |
| 273 | * configured yet. |
| 274 | */ |
| 275 | BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP); |
| 276 | vma->vm_end = STACK_TOP_MAX; |
| 277 | vma->vm_start = vma->vm_end - PAGE_SIZE; |
| 278 | vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; |
| 279 | vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); |
| 280 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
| 281 | |
| 282 | err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1); |
| 283 | if (err) |
| 284 | goto err; |
| 285 | |
| 286 | err = insert_vm_struct(mm, vma); |
| 287 | if (err) |
| 288 | goto err; |
| 289 | |
| 290 | mm->stack_vm = mm->total_vm = 1; |
| 291 | up_write(&mm->mmap_sem); |
| 292 | bprm->p = vma->vm_end - sizeof(void *); |
| 293 | return 0; |
| 294 | err: |
| 295 | up_write(&mm->mmap_sem); |
| 296 | bprm->vma = NULL; |
| 297 | kmem_cache_free(vm_area_cachep, vma); |
| 298 | return err; |
| 299 | } |
| 300 | |
| 301 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
| 302 | { |
| 303 | return len <= MAX_ARG_STRLEN; |
| 304 | } |
| 305 | |
| 306 | #else |
| 307 | |
| 308 | void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) |
| 309 | { |
| 310 | } |
| 311 | |
| 312 | struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| 313 | int write) |
| 314 | { |
| 315 | struct page *page; |
| 316 | |
| 317 | page = bprm->page[pos / PAGE_SIZE]; |
| 318 | if (!page && write) { |
| 319 | page = alloc_page(GFP_HIGHUSER|__GFP_ZERO); |
| 320 | if (!page) |
| 321 | return NULL; |
| 322 | bprm->page[pos / PAGE_SIZE] = page; |
| 323 | } |
| 324 | |
| 325 | return page; |
| 326 | } |
| 327 | |
| 328 | static void put_arg_page(struct page *page) |
| 329 | { |
| 330 | } |
| 331 | |
| 332 | static void free_arg_page(struct linux_binprm *bprm, int i) |
| 333 | { |
| 334 | if (bprm->page[i]) { |
| 335 | __free_page(bprm->page[i]); |
| 336 | bprm->page[i] = NULL; |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | static void free_arg_pages(struct linux_binprm *bprm) |
| 341 | { |
| 342 | int i; |
| 343 | |
| 344 | for (i = 0; i < MAX_ARG_PAGES; i++) |
| 345 | free_arg_page(bprm, i); |
| 346 | } |
| 347 | |
| 348 | static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos, |
| 349 | struct page *page) |
| 350 | { |
| 351 | } |
| 352 | |
| 353 | static int __bprm_mm_init(struct linux_binprm *bprm) |
| 354 | { |
| 355 | bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *); |
| 356 | return 0; |
| 357 | } |
| 358 | |
| 359 | static bool valid_arg_len(struct linux_binprm *bprm, long len) |
| 360 | { |
| 361 | return len <= bprm->p; |
| 362 | } |
| 363 | |
| 364 | #endif /* CONFIG_MMU */ |
| 365 | |
| 366 | /* |
| 367 | * Create a new mm_struct and populate it with a temporary stack |
| 368 | * vm_area_struct. We don't have enough context at this point to set the stack |
| 369 | * flags, permissions, and offset, so we use temporary values. We'll update |
| 370 | * them later in setup_arg_pages(). |
| 371 | */ |
| 372 | int bprm_mm_init(struct linux_binprm *bprm) |
| 373 | { |
| 374 | int err; |
| 375 | struct mm_struct *mm = NULL; |
| 376 | |
| 377 | bprm->mm = mm = mm_alloc(); |
| 378 | err = -ENOMEM; |
| 379 | if (!mm) |
| 380 | goto err; |
| 381 | |
| 382 | err = init_new_context(current, mm); |
| 383 | if (err) |
| 384 | goto err; |
| 385 | |
| 386 | err = __bprm_mm_init(bprm); |
| 387 | if (err) |
| 388 | goto err; |
| 389 | |
| 390 | return 0; |
| 391 | |
| 392 | err: |
| 393 | if (mm) { |
| 394 | bprm->mm = NULL; |
| 395 | mmdrop(mm); |
| 396 | } |
| 397 | |
| 398 | return err; |
| 399 | } |
| 400 | |
| 401 | /* |
| 402 | * count() counts the number of strings in array ARGV. |
| 403 | */ |
| 404 | static int count(const char __user * const __user * argv, int max) |
| 405 | { |
| 406 | int i = 0; |
| 407 | |
| 408 | if (argv != NULL) { |
| 409 | for (;;) { |
| 410 | const char __user * p; |
| 411 | |
| 412 | if (get_user(p, argv)) |
| 413 | return -EFAULT; |
| 414 | if (!p) |
| 415 | break; |
| 416 | argv++; |
| 417 | if (i++ >= max) |
| 418 | return -E2BIG; |
| 419 | |
| 420 | if (fatal_signal_pending(current)) |
| 421 | return -ERESTARTNOHAND; |
| 422 | cond_resched(); |
| 423 | } |
| 424 | } |
| 425 | return i; |
| 426 | } |
| 427 | |
| 428 | /* |
| 429 | * 'copy_strings()' copies argument/environment strings from the old |
| 430 | * processes's memory to the new process's stack. The call to get_user_pages() |
| 431 | * ensures the destination page is created and not swapped out. |
| 432 | */ |
| 433 | static int copy_strings(int argc, const char __user *const __user *argv, |
| 434 | struct linux_binprm *bprm) |
| 435 | { |
| 436 | struct page *kmapped_page = NULL; |
| 437 | char *kaddr = NULL; |
| 438 | unsigned long kpos = 0; |
| 439 | int ret; |
| 440 | |
| 441 | while (argc-- > 0) { |
| 442 | const char __user *str; |
| 443 | int len; |
| 444 | unsigned long pos; |
| 445 | |
| 446 | if (get_user(str, argv+argc) || |
| 447 | !(len = strnlen_user(str, MAX_ARG_STRLEN))) { |
| 448 | ret = -EFAULT; |
| 449 | goto out; |
| 450 | } |
| 451 | |
| 452 | if (!valid_arg_len(bprm, len)) { |
| 453 | ret = -E2BIG; |
| 454 | goto out; |
| 455 | } |
| 456 | |
| 457 | /* We're going to work our way backwords. */ |
| 458 | pos = bprm->p; |
| 459 | str += len; |
| 460 | bprm->p -= len; |
| 461 | |
| 462 | while (len > 0) { |
| 463 | int offset, bytes_to_copy; |
| 464 | |
| 465 | if (fatal_signal_pending(current)) { |
| 466 | ret = -ERESTARTNOHAND; |
| 467 | goto out; |
| 468 | } |
| 469 | cond_resched(); |
| 470 | |
| 471 | offset = pos % PAGE_SIZE; |
| 472 | if (offset == 0) |
| 473 | offset = PAGE_SIZE; |
| 474 | |
| 475 | bytes_to_copy = offset; |
| 476 | if (bytes_to_copy > len) |
| 477 | bytes_to_copy = len; |
| 478 | |
| 479 | offset -= bytes_to_copy; |
| 480 | pos -= bytes_to_copy; |
| 481 | str -= bytes_to_copy; |
| 482 | len -= bytes_to_copy; |
| 483 | |
| 484 | if (!kmapped_page || kpos != (pos & PAGE_MASK)) { |
| 485 | struct page *page; |
| 486 | |
| 487 | page = get_arg_page(bprm, pos, 1); |
| 488 | if (!page) { |
| 489 | ret = -E2BIG; |
| 490 | goto out; |
| 491 | } |
| 492 | |
| 493 | if (kmapped_page) { |
| 494 | flush_kernel_dcache_page(kmapped_page); |
| 495 | kunmap(kmapped_page); |
| 496 | put_arg_page(kmapped_page); |
| 497 | } |
| 498 | kmapped_page = page; |
| 499 | kaddr = kmap(kmapped_page); |
| 500 | kpos = pos & PAGE_MASK; |
| 501 | flush_arg_page(bprm, kpos, kmapped_page); |
| 502 | } |
| 503 | if (copy_from_user(kaddr+offset, str, bytes_to_copy)) { |
| 504 | ret = -EFAULT; |
| 505 | goto out; |
| 506 | } |
| 507 | } |
| 508 | } |
| 509 | ret = 0; |
| 510 | out: |
| 511 | if (kmapped_page) { |
| 512 | flush_kernel_dcache_page(kmapped_page); |
| 513 | kunmap(kmapped_page); |
| 514 | put_arg_page(kmapped_page); |
| 515 | } |
| 516 | return ret; |
| 517 | } |
| 518 | |
| 519 | /* |
| 520 | * Like copy_strings, but get argv and its values from kernel memory. |
| 521 | */ |
| 522 | int copy_strings_kernel(int argc, const char *const *argv, |
| 523 | struct linux_binprm *bprm) |
| 524 | { |
| 525 | int r; |
| 526 | mm_segment_t oldfs = get_fs(); |
| 527 | set_fs(KERNEL_DS); |
| 528 | r = copy_strings(argc, (const char __user *const __user *)argv, bprm); |
| 529 | set_fs(oldfs); |
| 530 | return r; |
| 531 | } |
| 532 | EXPORT_SYMBOL(copy_strings_kernel); |
| 533 | |
| 534 | #ifdef CONFIG_MMU |
| 535 | |
| 536 | /* |
| 537 | * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once |
| 538 | * the binfmt code determines where the new stack should reside, we shift it to |
| 539 | * its final location. The process proceeds as follows: |
| 540 | * |
| 541 | * 1) Use shift to calculate the new vma endpoints. |
| 542 | * 2) Extend vma to cover both the old and new ranges. This ensures the |
| 543 | * arguments passed to subsequent functions are consistent. |
| 544 | * 3) Move vma's page tables to the new range. |
| 545 | * 4) Free up any cleared pgd range. |
| 546 | * 5) Shrink the vma to cover only the new range. |
| 547 | */ |
| 548 | static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift) |
| 549 | { |
| 550 | struct mm_struct *mm = vma->vm_mm; |
| 551 | unsigned long old_start = vma->vm_start; |
| 552 | unsigned long old_end = vma->vm_end; |
| 553 | unsigned long length = old_end - old_start; |
| 554 | unsigned long new_start = old_start - shift; |
| 555 | unsigned long new_end = old_end - shift; |
| 556 | struct mmu_gather *tlb; |
| 557 | |
| 558 | BUG_ON(new_start > new_end); |
| 559 | |
| 560 | /* |
| 561 | * ensure there are no vmas between where we want to go |
| 562 | * and where we are |
| 563 | */ |
| 564 | if (vma != find_vma(mm, new_start)) |
| 565 | return -EFAULT; |
| 566 | |
| 567 | /* |
| 568 | * cover the whole range: [new_start, old_end) |
| 569 | */ |
| 570 | if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL)) |
| 571 | return -ENOMEM; |
| 572 | |
| 573 | /* |
| 574 | * move the page tables downwards, on failure we rely on |
| 575 | * process cleanup to remove whatever mess we made. |
| 576 | */ |
| 577 | if (length != move_page_tables(vma, old_start, |
| 578 | vma, new_start, length)) |
| 579 | return -ENOMEM; |
| 580 | |
| 581 | lru_add_drain(); |
| 582 | tlb = tlb_gather_mmu(mm, 0); |
| 583 | if (new_end > old_start) { |
| 584 | /* |
| 585 | * when the old and new regions overlap clear from new_end. |
| 586 | */ |
| 587 | free_pgd_range(tlb, new_end, old_end, new_end, |
| 588 | vma->vm_next ? vma->vm_next->vm_start : 0); |
| 589 | } else { |
| 590 | /* |
| 591 | * otherwise, clean from old_start; this is done to not touch |
| 592 | * the address space in [new_end, old_start) some architectures |
| 593 | * have constraints on va-space that make this illegal (IA64) - |
| 594 | * for the others its just a little faster. |
| 595 | */ |
| 596 | free_pgd_range(tlb, old_start, old_end, new_end, |
| 597 | vma->vm_next ? vma->vm_next->vm_start : 0); |
| 598 | } |
| 599 | tlb_finish_mmu(tlb, new_end, old_end); |
| 600 | |
| 601 | /* |
| 602 | * Shrink the vma to just the new range. Always succeeds. |
| 603 | */ |
| 604 | vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); |
| 605 | |
| 606 | return 0; |
| 607 | } |
| 608 | |
| 609 | /* |
| 610 | * Finalizes the stack vm_area_struct. The flags and permissions are updated, |
| 611 | * the stack is optionally relocated, and some extra space is added. |
| 612 | */ |
| 613 | int setup_arg_pages(struct linux_binprm *bprm, |
| 614 | unsigned long stack_top, |
| 615 | int executable_stack) |
| 616 | { |
| 617 | unsigned long ret; |
| 618 | unsigned long stack_shift; |
| 619 | struct mm_struct *mm = current->mm; |
| 620 | struct vm_area_struct *vma = bprm->vma; |
| 621 | struct vm_area_struct *prev = NULL; |
| 622 | unsigned long vm_flags; |
| 623 | unsigned long stack_base; |
| 624 | unsigned long stack_size; |
| 625 | unsigned long stack_expand; |
| 626 | unsigned long rlim_stack; |
| 627 | |
| 628 | #ifdef CONFIG_STACK_GROWSUP |
| 629 | /* Limit stack size to 1GB */ |
| 630 | stack_base = rlimit_max(RLIMIT_STACK); |
| 631 | if (stack_base > (1 << 30)) |
| 632 | stack_base = 1 << 30; |
| 633 | |
| 634 | /* Make sure we didn't let the argument array grow too large. */ |
| 635 | if (vma->vm_end - vma->vm_start > stack_base) |
| 636 | return -ENOMEM; |
| 637 | |
| 638 | stack_base = PAGE_ALIGN(stack_top - stack_base); |
| 639 | |
| 640 | stack_shift = vma->vm_start - stack_base; |
| 641 | mm->arg_start = bprm->p - stack_shift; |
| 642 | bprm->p = vma->vm_end - stack_shift; |
| 643 | #else |
| 644 | stack_top = arch_align_stack(stack_top); |
| 645 | stack_top = PAGE_ALIGN(stack_top); |
| 646 | |
| 647 | if (unlikely(stack_top < mmap_min_addr) || |
| 648 | unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr)) |
| 649 | return -ENOMEM; |
| 650 | |
| 651 | stack_shift = vma->vm_end - stack_top; |
| 652 | |
| 653 | bprm->p -= stack_shift; |
| 654 | mm->arg_start = bprm->p; |
| 655 | #endif |
| 656 | |
| 657 | if (bprm->loader) |
| 658 | bprm->loader -= stack_shift; |
| 659 | bprm->exec -= stack_shift; |
| 660 | |
| 661 | down_write(&mm->mmap_sem); |
| 662 | vm_flags = VM_STACK_FLAGS; |
| 663 | |
| 664 | /* |
| 665 | * Adjust stack execute permissions; explicitly enable for |
| 666 | * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone |
| 667 | * (arch default) otherwise. |
| 668 | */ |
| 669 | if (unlikely(executable_stack == EXSTACK_ENABLE_X)) |
| 670 | vm_flags |= VM_EXEC; |
| 671 | else if (executable_stack == EXSTACK_DISABLE_X) |
| 672 | vm_flags &= ~VM_EXEC; |
| 673 | vm_flags |= mm->def_flags; |
| 674 | vm_flags |= VM_STACK_INCOMPLETE_SETUP; |
| 675 | |
| 676 | ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end, |
| 677 | vm_flags); |
| 678 | if (ret) |
| 679 | goto out_unlock; |
| 680 | BUG_ON(prev != vma); |
| 681 | |
| 682 | /* Move stack pages down in memory. */ |
| 683 | if (stack_shift) { |
| 684 | ret = shift_arg_pages(vma, stack_shift); |
| 685 | if (ret) |
| 686 | goto out_unlock; |
| 687 | } |
| 688 | |
| 689 | /* mprotect_fixup is overkill to remove the temporary stack flags */ |
| 690 | vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP; |
| 691 | |
| 692 | stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */ |
| 693 | stack_size = vma->vm_end - vma->vm_start; |
| 694 | /* |
| 695 | * Align this down to a page boundary as expand_stack |
| 696 | * will align it up. |
| 697 | */ |
| 698 | rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; |
| 699 | #ifdef CONFIG_STACK_GROWSUP |
| 700 | if (stack_size + stack_expand > rlim_stack) |
| 701 | stack_base = vma->vm_start + rlim_stack; |
| 702 | else |
| 703 | stack_base = vma->vm_end + stack_expand; |
| 704 | #else |
| 705 | if (stack_size + stack_expand > rlim_stack) |
| 706 | stack_base = vma->vm_end - rlim_stack; |
| 707 | else |
| 708 | stack_base = vma->vm_start - stack_expand; |
| 709 | #endif |
| 710 | current->mm->start_stack = bprm->p; |
| 711 | ret = expand_stack(vma, stack_base); |
| 712 | if (ret) |
| 713 | ret = -EFAULT; |
| 714 | |
| 715 | out_unlock: |
| 716 | up_write(&mm->mmap_sem); |
| 717 | return ret; |
| 718 | } |
| 719 | EXPORT_SYMBOL(setup_arg_pages); |
| 720 | |
| 721 | #endif /* CONFIG_MMU */ |
| 722 | |
| 723 | struct file *open_exec(const char *name) |
| 724 | { |
| 725 | struct file *file; |
| 726 | int err; |
| 727 | static const struct open_flags open_exec_flags = { |
| 728 | .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC, |
| 729 | .acc_mode = MAY_EXEC | MAY_OPEN, |
| 730 | .intent = LOOKUP_OPEN |
| 731 | }; |
| 732 | |
| 733 | file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW); |
| 734 | if (IS_ERR(file)) |
| 735 | goto out; |
| 736 | |
| 737 | err = -EACCES; |
| 738 | if (!S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
| 739 | goto exit; |
| 740 | |
| 741 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) |
| 742 | goto exit; |
| 743 | |
| 744 | fsnotify_open(file); |
| 745 | |
| 746 | err = deny_write_access(file); |
| 747 | if (err) |
| 748 | goto exit; |
| 749 | |
| 750 | out: |
| 751 | return file; |
| 752 | |
| 753 | exit: |
| 754 | fput(file); |
| 755 | return ERR_PTR(err); |
| 756 | } |
| 757 | EXPORT_SYMBOL(open_exec); |
| 758 | |
| 759 | int kernel_read(struct file *file, loff_t offset, |
| 760 | char *addr, unsigned long count) |
| 761 | { |
| 762 | mm_segment_t old_fs; |
| 763 | loff_t pos = offset; |
| 764 | int result; |
| 765 | |
| 766 | old_fs = get_fs(); |
| 767 | set_fs(get_ds()); |
| 768 | /* The cast to a user pointer is valid due to the set_fs() */ |
| 769 | result = vfs_read(file, (void __user *)addr, count, &pos); |
| 770 | set_fs(old_fs); |
| 771 | return result; |
| 772 | } |
| 773 | |
| 774 | EXPORT_SYMBOL(kernel_read); |
| 775 | |
| 776 | static int exec_mmap(struct mm_struct *mm) |
| 777 | { |
| 778 | struct task_struct *tsk; |
| 779 | struct mm_struct * old_mm, *active_mm; |
| 780 | |
| 781 | /* Notify parent that we're no longer interested in the old VM */ |
| 782 | tsk = current; |
| 783 | old_mm = current->mm; |
| 784 | sync_mm_rss(tsk, old_mm); |
| 785 | mm_release(tsk, old_mm); |
| 786 | |
| 787 | if (old_mm) { |
| 788 | /* |
| 789 | * Make sure that if there is a core dump in progress |
| 790 | * for the old mm, we get out and die instead of going |
| 791 | * through with the exec. We must hold mmap_sem around |
| 792 | * checking core_state and changing tsk->mm. |
| 793 | */ |
| 794 | down_read(&old_mm->mmap_sem); |
| 795 | if (unlikely(old_mm->core_state)) { |
| 796 | up_read(&old_mm->mmap_sem); |
| 797 | return -EINTR; |
| 798 | } |
| 799 | } |
| 800 | task_lock(tsk); |
| 801 | active_mm = tsk->active_mm; |
| 802 | tsk->mm = mm; |
| 803 | tsk->active_mm = mm; |
| 804 | activate_mm(active_mm, mm); |
| 805 | if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { |
| 806 | atomic_dec(&old_mm->oom_disable_count); |
| 807 | atomic_inc(&tsk->mm->oom_disable_count); |
| 808 | } |
| 809 | task_unlock(tsk); |
| 810 | arch_pick_mmap_layout(mm); |
| 811 | if (old_mm) { |
| 812 | up_read(&old_mm->mmap_sem); |
| 813 | BUG_ON(active_mm != old_mm); |
| 814 | mm_update_next_owner(old_mm); |
| 815 | mmput(old_mm); |
| 816 | return 0; |
| 817 | } |
| 818 | mmdrop(active_mm); |
| 819 | return 0; |
| 820 | } |
| 821 | |
| 822 | /* |
| 823 | * This function makes sure the current process has its own signal table, |
| 824 | * so that flush_signal_handlers can later reset the handlers without |
| 825 | * disturbing other processes. (Other processes might share the signal |
| 826 | * table via the CLONE_SIGHAND option to clone().) |
| 827 | */ |
| 828 | static int de_thread(struct task_struct *tsk) |
| 829 | { |
| 830 | struct signal_struct *sig = tsk->signal; |
| 831 | struct sighand_struct *oldsighand = tsk->sighand; |
| 832 | spinlock_t *lock = &oldsighand->siglock; |
| 833 | |
| 834 | if (thread_group_empty(tsk)) |
| 835 | goto no_thread_group; |
| 836 | |
| 837 | /* |
| 838 | * Kill all other threads in the thread group. |
| 839 | */ |
| 840 | spin_lock_irq(lock); |
| 841 | if (signal_group_exit(sig)) { |
| 842 | /* |
| 843 | * Another group action in progress, just |
| 844 | * return so that the signal is processed. |
| 845 | */ |
| 846 | spin_unlock_irq(lock); |
| 847 | return -EAGAIN; |
| 848 | } |
| 849 | |
| 850 | sig->group_exit_task = tsk; |
| 851 | sig->notify_count = zap_other_threads(tsk); |
| 852 | if (!thread_group_leader(tsk)) |
| 853 | sig->notify_count--; |
| 854 | |
| 855 | while (sig->notify_count) { |
| 856 | __set_current_state(TASK_UNINTERRUPTIBLE); |
| 857 | spin_unlock_irq(lock); |
| 858 | schedule(); |
| 859 | spin_lock_irq(lock); |
| 860 | } |
| 861 | spin_unlock_irq(lock); |
| 862 | |
| 863 | /* |
| 864 | * At this point all other threads have exited, all we have to |
| 865 | * do is to wait for the thread group leader to become inactive, |
| 866 | * and to assume its PID: |
| 867 | */ |
| 868 | if (!thread_group_leader(tsk)) { |
| 869 | struct task_struct *leader = tsk->group_leader; |
| 870 | |
| 871 | sig->notify_count = -1; /* for exit_notify() */ |
| 872 | for (;;) { |
| 873 | write_lock_irq(&tasklist_lock); |
| 874 | if (likely(leader->exit_state)) |
| 875 | break; |
| 876 | __set_current_state(TASK_UNINTERRUPTIBLE); |
| 877 | write_unlock_irq(&tasklist_lock); |
| 878 | schedule(); |
| 879 | } |
| 880 | |
| 881 | /* |
| 882 | * The only record we have of the real-time age of a |
| 883 | * process, regardless of execs it's done, is start_time. |
| 884 | * All the past CPU time is accumulated in signal_struct |
| 885 | * from sister threads now dead. But in this non-leader |
| 886 | * exec, nothing survives from the original leader thread, |
| 887 | * whose birth marks the true age of this process now. |
| 888 | * When we take on its identity by switching to its PID, we |
| 889 | * also take its birthdate (always earlier than our own). |
| 890 | */ |
| 891 | tsk->start_time = leader->start_time; |
| 892 | |
| 893 | BUG_ON(!same_thread_group(leader, tsk)); |
| 894 | BUG_ON(has_group_leader_pid(tsk)); |
| 895 | /* |
| 896 | * An exec() starts a new thread group with the |
| 897 | * TGID of the previous thread group. Rehash the |
| 898 | * two threads with a switched PID, and release |
| 899 | * the former thread group leader: |
| 900 | */ |
| 901 | |
| 902 | /* Become a process group leader with the old leader's pid. |
| 903 | * The old leader becomes a thread of the this thread group. |
| 904 | * Note: The old leader also uses this pid until release_task |
| 905 | * is called. Odd but simple and correct. |
| 906 | */ |
| 907 | detach_pid(tsk, PIDTYPE_PID); |
| 908 | tsk->pid = leader->pid; |
| 909 | attach_pid(tsk, PIDTYPE_PID, task_pid(leader)); |
| 910 | transfer_pid(leader, tsk, PIDTYPE_PGID); |
| 911 | transfer_pid(leader, tsk, PIDTYPE_SID); |
| 912 | |
| 913 | list_replace_rcu(&leader->tasks, &tsk->tasks); |
| 914 | list_replace_init(&leader->sibling, &tsk->sibling); |
| 915 | |
| 916 | tsk->group_leader = tsk; |
| 917 | leader->group_leader = tsk; |
| 918 | |
| 919 | tsk->exit_signal = SIGCHLD; |
| 920 | |
| 921 | BUG_ON(leader->exit_state != EXIT_ZOMBIE); |
| 922 | leader->exit_state = EXIT_DEAD; |
| 923 | write_unlock_irq(&tasklist_lock); |
| 924 | |
| 925 | release_task(leader); |
| 926 | } |
| 927 | |
| 928 | sig->group_exit_task = NULL; |
| 929 | sig->notify_count = 0; |
| 930 | |
| 931 | no_thread_group: |
| 932 | if (current->mm) |
| 933 | setmax_mm_hiwater_rss(&sig->maxrss, current->mm); |
| 934 | |
| 935 | exit_itimers(sig); |
| 936 | flush_itimer_signals(); |
| 937 | |
| 938 | if (atomic_read(&oldsighand->count) != 1) { |
| 939 | struct sighand_struct *newsighand; |
| 940 | /* |
| 941 | * This ->sighand is shared with the CLONE_SIGHAND |
| 942 | * but not CLONE_THREAD task, switch to the new one. |
| 943 | */ |
| 944 | newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
| 945 | if (!newsighand) |
| 946 | return -ENOMEM; |
| 947 | |
| 948 | atomic_set(&newsighand->count, 1); |
| 949 | memcpy(newsighand->action, oldsighand->action, |
| 950 | sizeof(newsighand->action)); |
| 951 | |
| 952 | write_lock_irq(&tasklist_lock); |
| 953 | spin_lock(&oldsighand->siglock); |
| 954 | rcu_assign_pointer(tsk->sighand, newsighand); |
| 955 | spin_unlock(&oldsighand->siglock); |
| 956 | write_unlock_irq(&tasklist_lock); |
| 957 | |
| 958 | __cleanup_sighand(oldsighand); |
| 959 | } |
| 960 | |
| 961 | BUG_ON(!thread_group_leader(tsk)); |
| 962 | return 0; |
| 963 | } |
| 964 | |
| 965 | /* |
| 966 | * These functions flushes out all traces of the currently running executable |
| 967 | * so that a new one can be started |
| 968 | */ |
| 969 | static void flush_old_files(struct files_struct * files) |
| 970 | { |
| 971 | long j = -1; |
| 972 | struct fdtable *fdt; |
| 973 | |
| 974 | spin_lock(&files->file_lock); |
| 975 | for (;;) { |
| 976 | unsigned long set, i; |
| 977 | |
| 978 | j++; |
| 979 | i = j * __NFDBITS; |
| 980 | fdt = files_fdtable(files); |
| 981 | if (i >= fdt->max_fds) |
| 982 | break; |
| 983 | set = fdt->close_on_exec->fds_bits[j]; |
| 984 | if (!set) |
| 985 | continue; |
| 986 | fdt->close_on_exec->fds_bits[j] = 0; |
| 987 | spin_unlock(&files->file_lock); |
| 988 | for ( ; set ; i++,set >>= 1) { |
| 989 | if (set & 1) { |
| 990 | sys_close(i); |
| 991 | } |
| 992 | } |
| 993 | spin_lock(&files->file_lock); |
| 994 | |
| 995 | } |
| 996 | spin_unlock(&files->file_lock); |
| 997 | } |
| 998 | |
| 999 | char *get_task_comm(char *buf, struct task_struct *tsk) |
| 1000 | { |
| 1001 | /* buf must be at least sizeof(tsk->comm) in size */ |
| 1002 | task_lock(tsk); |
| 1003 | strncpy(buf, tsk->comm, sizeof(tsk->comm)); |
| 1004 | task_unlock(tsk); |
| 1005 | return buf; |
| 1006 | } |
| 1007 | |
| 1008 | void set_task_comm(struct task_struct *tsk, char *buf) |
| 1009 | { |
| 1010 | task_lock(tsk); |
| 1011 | |
| 1012 | /* |
| 1013 | * Threads may access current->comm without holding |
| 1014 | * the task lock, so write the string carefully. |
| 1015 | * Readers without a lock may see incomplete new |
| 1016 | * names but are safe from non-terminating string reads. |
| 1017 | */ |
| 1018 | memset(tsk->comm, 0, TASK_COMM_LEN); |
| 1019 | wmb(); |
| 1020 | strlcpy(tsk->comm, buf, sizeof(tsk->comm)); |
| 1021 | task_unlock(tsk); |
| 1022 | perf_event_comm(tsk); |
| 1023 | } |
| 1024 | |
| 1025 | int flush_old_exec(struct linux_binprm * bprm) |
| 1026 | { |
| 1027 | int retval; |
| 1028 | |
| 1029 | /* |
| 1030 | * Make sure we have a private signal table and that |
| 1031 | * we are unassociated from the previous thread group. |
| 1032 | */ |
| 1033 | retval = de_thread(current); |
| 1034 | if (retval) |
| 1035 | goto out; |
| 1036 | |
| 1037 | set_mm_exe_file(bprm->mm, bprm->file); |
| 1038 | |
| 1039 | /* |
| 1040 | * Release all of the old mmap stuff |
| 1041 | */ |
| 1042 | acct_arg_size(bprm, 0); |
| 1043 | retval = exec_mmap(bprm->mm); |
| 1044 | if (retval) |
| 1045 | goto out; |
| 1046 | |
| 1047 | bprm->mm = NULL; /* We're using it now */ |
| 1048 | |
| 1049 | current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD); |
| 1050 | flush_thread(); |
| 1051 | current->personality &= ~bprm->per_clear; |
| 1052 | |
| 1053 | return 0; |
| 1054 | |
| 1055 | out: |
| 1056 | return retval; |
| 1057 | } |
| 1058 | EXPORT_SYMBOL(flush_old_exec); |
| 1059 | |
| 1060 | void setup_new_exec(struct linux_binprm * bprm) |
| 1061 | { |
| 1062 | int i, ch; |
| 1063 | const char *name; |
| 1064 | char tcomm[sizeof(current->comm)]; |
| 1065 | |
| 1066 | arch_pick_mmap_layout(current->mm); |
| 1067 | |
| 1068 | /* This is the point of no return */ |
| 1069 | current->sas_ss_sp = current->sas_ss_size = 0; |
| 1070 | |
| 1071 | if (current_euid() == current_uid() && current_egid() == current_gid()) |
| 1072 | set_dumpable(current->mm, 1); |
| 1073 | else |
| 1074 | set_dumpable(current->mm, suid_dumpable); |
| 1075 | |
| 1076 | name = bprm->filename; |
| 1077 | |
| 1078 | /* Copies the binary name from after last slash */ |
| 1079 | for (i=0; (ch = *(name++)) != '\0';) { |
| 1080 | if (ch == '/') |
| 1081 | i = 0; /* overwrite what we wrote */ |
| 1082 | else |
| 1083 | if (i < (sizeof(tcomm) - 1)) |
| 1084 | tcomm[i++] = ch; |
| 1085 | } |
| 1086 | tcomm[i] = '\0'; |
| 1087 | set_task_comm(current, tcomm); |
| 1088 | |
| 1089 | /* Set the new mm task size. We have to do that late because it may |
| 1090 | * depend on TIF_32BIT which is only updated in flush_thread() on |
| 1091 | * some architectures like powerpc |
| 1092 | */ |
| 1093 | current->mm->task_size = TASK_SIZE; |
| 1094 | |
| 1095 | /* install the new credentials */ |
| 1096 | if (bprm->cred->uid != current_euid() || |
| 1097 | bprm->cred->gid != current_egid()) { |
| 1098 | current->pdeath_signal = 0; |
| 1099 | } else if (file_permission(bprm->file, MAY_READ) || |
| 1100 | bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) { |
| 1101 | set_dumpable(current->mm, suid_dumpable); |
| 1102 | } |
| 1103 | |
| 1104 | /* |
| 1105 | * Flush performance counters when crossing a |
| 1106 | * security domain: |
| 1107 | */ |
| 1108 | if (!get_dumpable(current->mm)) |
| 1109 | perf_event_exit_task(current); |
| 1110 | |
| 1111 | /* An exec changes our domain. We are no longer part of the thread |
| 1112 | group */ |
| 1113 | |
| 1114 | current->self_exec_id++; |
| 1115 | |
| 1116 | flush_signal_handlers(current, 0); |
| 1117 | flush_old_files(current->files); |
| 1118 | } |
| 1119 | EXPORT_SYMBOL(setup_new_exec); |
| 1120 | |
| 1121 | /* |
| 1122 | * Prepare credentials and lock ->cred_guard_mutex. |
| 1123 | * install_exec_creds() commits the new creds and drops the lock. |
| 1124 | * Or, if exec fails before, free_bprm() should release ->cred and |
| 1125 | * and unlock. |
| 1126 | */ |
| 1127 | int prepare_bprm_creds(struct linux_binprm *bprm) |
| 1128 | { |
| 1129 | if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) |
| 1130 | return -ERESTARTNOINTR; |
| 1131 | |
| 1132 | bprm->cred = prepare_exec_creds(); |
| 1133 | if (likely(bprm->cred)) |
| 1134 | return 0; |
| 1135 | |
| 1136 | mutex_unlock(¤t->signal->cred_guard_mutex); |
| 1137 | return -ENOMEM; |
| 1138 | } |
| 1139 | |
| 1140 | void free_bprm(struct linux_binprm *bprm) |
| 1141 | { |
| 1142 | free_arg_pages(bprm); |
| 1143 | if (bprm->cred) { |
| 1144 | mutex_unlock(¤t->signal->cred_guard_mutex); |
| 1145 | abort_creds(bprm->cred); |
| 1146 | } |
| 1147 | kfree(bprm); |
| 1148 | } |
| 1149 | |
| 1150 | /* |
| 1151 | * install the new credentials for this executable |
| 1152 | */ |
| 1153 | void install_exec_creds(struct linux_binprm *bprm) |
| 1154 | { |
| 1155 | security_bprm_committing_creds(bprm); |
| 1156 | |
| 1157 | commit_creds(bprm->cred); |
| 1158 | bprm->cred = NULL; |
| 1159 | /* |
| 1160 | * cred_guard_mutex must be held at least to this point to prevent |
| 1161 | * ptrace_attach() from altering our determination of the task's |
| 1162 | * credentials; any time after this it may be unlocked. |
| 1163 | */ |
| 1164 | security_bprm_committed_creds(bprm); |
| 1165 | mutex_unlock(¤t->signal->cred_guard_mutex); |
| 1166 | } |
| 1167 | EXPORT_SYMBOL(install_exec_creds); |
| 1168 | |
| 1169 | /* |
| 1170 | * determine how safe it is to execute the proposed program |
| 1171 | * - the caller must hold ->cred_guard_mutex to protect against |
| 1172 | * PTRACE_ATTACH |
| 1173 | */ |
| 1174 | int check_unsafe_exec(struct linux_binprm *bprm) |
| 1175 | { |
| 1176 | struct task_struct *p = current, *t; |
| 1177 | unsigned n_fs; |
| 1178 | int res = 0; |
| 1179 | |
| 1180 | bprm->unsafe = tracehook_unsafe_exec(p); |
| 1181 | |
| 1182 | n_fs = 1; |
| 1183 | spin_lock(&p->fs->lock); |
| 1184 | rcu_read_lock(); |
| 1185 | for (t = next_thread(p); t != p; t = next_thread(t)) { |
| 1186 | if (t->fs == p->fs) |
| 1187 | n_fs++; |
| 1188 | } |
| 1189 | rcu_read_unlock(); |
| 1190 | |
| 1191 | if (p->fs->users > n_fs) { |
| 1192 | bprm->unsafe |= LSM_UNSAFE_SHARE; |
| 1193 | } else { |
| 1194 | res = -EAGAIN; |
| 1195 | if (!p->fs->in_exec) { |
| 1196 | p->fs->in_exec = 1; |
| 1197 | res = 1; |
| 1198 | } |
| 1199 | } |
| 1200 | spin_unlock(&p->fs->lock); |
| 1201 | |
| 1202 | return res; |
| 1203 | } |
| 1204 | |
| 1205 | /* |
| 1206 | * Fill the binprm structure from the inode. |
| 1207 | * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes |
| 1208 | * |
| 1209 | * This may be called multiple times for binary chains (scripts for example). |
| 1210 | */ |
| 1211 | int prepare_binprm(struct linux_binprm *bprm) |
| 1212 | { |
| 1213 | umode_t mode; |
| 1214 | struct inode * inode = bprm->file->f_path.dentry->d_inode; |
| 1215 | int retval; |
| 1216 | |
| 1217 | mode = inode->i_mode; |
| 1218 | if (bprm->file->f_op == NULL) |
| 1219 | return -EACCES; |
| 1220 | |
| 1221 | /* clear any previous set[ug]id data from a previous binary */ |
| 1222 | bprm->cred->euid = current_euid(); |
| 1223 | bprm->cred->egid = current_egid(); |
| 1224 | |
| 1225 | if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) { |
| 1226 | /* Set-uid? */ |
| 1227 | if (mode & S_ISUID) { |
| 1228 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
| 1229 | bprm->cred->euid = inode->i_uid; |
| 1230 | } |
| 1231 | |
| 1232 | /* Set-gid? */ |
| 1233 | /* |
| 1234 | * If setgid is set but no group execute bit then this |
| 1235 | * is a candidate for mandatory locking, not a setgid |
| 1236 | * executable. |
| 1237 | */ |
| 1238 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
| 1239 | bprm->per_clear |= PER_CLEAR_ON_SETID; |
| 1240 | bprm->cred->egid = inode->i_gid; |
| 1241 | } |
| 1242 | } |
| 1243 | |
| 1244 | /* fill in binprm security blob */ |
| 1245 | retval = security_bprm_set_creds(bprm); |
| 1246 | if (retval) |
| 1247 | return retval; |
| 1248 | bprm->cred_prepared = 1; |
| 1249 | |
| 1250 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); |
| 1251 | return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); |
| 1252 | } |
| 1253 | |
| 1254 | EXPORT_SYMBOL(prepare_binprm); |
| 1255 | |
| 1256 | /* |
| 1257 | * Arguments are '\0' separated strings found at the location bprm->p |
| 1258 | * points to; chop off the first by relocating brpm->p to right after |
| 1259 | * the first '\0' encountered. |
| 1260 | */ |
| 1261 | int remove_arg_zero(struct linux_binprm *bprm) |
| 1262 | { |
| 1263 | int ret = 0; |
| 1264 | unsigned long offset; |
| 1265 | char *kaddr; |
| 1266 | struct page *page; |
| 1267 | |
| 1268 | if (!bprm->argc) |
| 1269 | return 0; |
| 1270 | |
| 1271 | do { |
| 1272 | offset = bprm->p & ~PAGE_MASK; |
| 1273 | page = get_arg_page(bprm, bprm->p, 0); |
| 1274 | if (!page) { |
| 1275 | ret = -EFAULT; |
| 1276 | goto out; |
| 1277 | } |
| 1278 | kaddr = kmap_atomic(page, KM_USER0); |
| 1279 | |
| 1280 | for (; offset < PAGE_SIZE && kaddr[offset]; |
| 1281 | offset++, bprm->p++) |
| 1282 | ; |
| 1283 | |
| 1284 | kunmap_atomic(kaddr, KM_USER0); |
| 1285 | put_arg_page(page); |
| 1286 | |
| 1287 | if (offset == PAGE_SIZE) |
| 1288 | free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1); |
| 1289 | } while (offset == PAGE_SIZE); |
| 1290 | |
| 1291 | bprm->p++; |
| 1292 | bprm->argc--; |
| 1293 | ret = 0; |
| 1294 | |
| 1295 | out: |
| 1296 | return ret; |
| 1297 | } |
| 1298 | EXPORT_SYMBOL(remove_arg_zero); |
| 1299 | |
| 1300 | /* |
| 1301 | * cycle the list of binary formats handler, until one recognizes the image |
| 1302 | */ |
| 1303 | int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs) |
| 1304 | { |
| 1305 | unsigned int depth = bprm->recursion_depth; |
| 1306 | int try,retval; |
| 1307 | struct linux_binfmt *fmt; |
| 1308 | |
| 1309 | retval = security_bprm_check(bprm); |
| 1310 | if (retval) |
| 1311 | return retval; |
| 1312 | |
| 1313 | /* kernel module loader fixup */ |
| 1314 | /* so we don't try to load run modprobe in kernel space. */ |
| 1315 | set_fs(USER_DS); |
| 1316 | |
| 1317 | retval = audit_bprm(bprm); |
| 1318 | if (retval) |
| 1319 | return retval; |
| 1320 | |
| 1321 | retval = -ENOENT; |
| 1322 | for (try=0; try<2; try++) { |
| 1323 | read_lock(&binfmt_lock); |
| 1324 | list_for_each_entry(fmt, &formats, lh) { |
| 1325 | int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary; |
| 1326 | if (!fn) |
| 1327 | continue; |
| 1328 | if (!try_module_get(fmt->module)) |
| 1329 | continue; |
| 1330 | read_unlock(&binfmt_lock); |
| 1331 | retval = fn(bprm, regs); |
| 1332 | /* |
| 1333 | * Restore the depth counter to its starting value |
| 1334 | * in this call, so we don't have to rely on every |
| 1335 | * load_binary function to restore it on return. |
| 1336 | */ |
| 1337 | bprm->recursion_depth = depth; |
| 1338 | if (retval >= 0) { |
| 1339 | if (depth == 0) |
| 1340 | tracehook_report_exec(fmt, bprm, regs); |
| 1341 | put_binfmt(fmt); |
| 1342 | allow_write_access(bprm->file); |
| 1343 | if (bprm->file) |
| 1344 | fput(bprm->file); |
| 1345 | bprm->file = NULL; |
| 1346 | current->did_exec = 1; |
| 1347 | proc_exec_connector(current); |
| 1348 | return retval; |
| 1349 | } |
| 1350 | read_lock(&binfmt_lock); |
| 1351 | put_binfmt(fmt); |
| 1352 | if (retval != -ENOEXEC || bprm->mm == NULL) |
| 1353 | break; |
| 1354 | if (!bprm->file) { |
| 1355 | read_unlock(&binfmt_lock); |
| 1356 | return retval; |
| 1357 | } |
| 1358 | } |
| 1359 | read_unlock(&binfmt_lock); |
| 1360 | if (retval != -ENOEXEC || bprm->mm == NULL) { |
| 1361 | break; |
| 1362 | #ifdef CONFIG_MODULES |
| 1363 | } else { |
| 1364 | #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e)) |
| 1365 | if (printable(bprm->buf[0]) && |
| 1366 | printable(bprm->buf[1]) && |
| 1367 | printable(bprm->buf[2]) && |
| 1368 | printable(bprm->buf[3])) |
| 1369 | break; /* -ENOEXEC */ |
| 1370 | request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2])); |
| 1371 | #endif |
| 1372 | } |
| 1373 | } |
| 1374 | return retval; |
| 1375 | } |
| 1376 | |
| 1377 | EXPORT_SYMBOL(search_binary_handler); |
| 1378 | |
| 1379 | /* |
| 1380 | * sys_execve() executes a new program. |
| 1381 | */ |
| 1382 | int do_execve(const char * filename, |
| 1383 | const char __user *const __user *argv, |
| 1384 | const char __user *const __user *envp, |
| 1385 | struct pt_regs * regs) |
| 1386 | { |
| 1387 | struct linux_binprm *bprm; |
| 1388 | struct file *file; |
| 1389 | struct files_struct *displaced; |
| 1390 | bool clear_in_exec; |
| 1391 | int retval; |
| 1392 | |
| 1393 | retval = unshare_files(&displaced); |
| 1394 | if (retval) |
| 1395 | goto out_ret; |
| 1396 | |
| 1397 | retval = -ENOMEM; |
| 1398 | bprm = kzalloc(sizeof(*bprm), GFP_KERNEL); |
| 1399 | if (!bprm) |
| 1400 | goto out_files; |
| 1401 | |
| 1402 | retval = prepare_bprm_creds(bprm); |
| 1403 | if (retval) |
| 1404 | goto out_free; |
| 1405 | |
| 1406 | retval = check_unsafe_exec(bprm); |
| 1407 | if (retval < 0) |
| 1408 | goto out_free; |
| 1409 | clear_in_exec = retval; |
| 1410 | current->in_execve = 1; |
| 1411 | |
| 1412 | file = open_exec(filename); |
| 1413 | retval = PTR_ERR(file); |
| 1414 | if (IS_ERR(file)) |
| 1415 | goto out_unmark; |
| 1416 | |
| 1417 | sched_exec(); |
| 1418 | |
| 1419 | bprm->file = file; |
| 1420 | bprm->filename = filename; |
| 1421 | bprm->interp = filename; |
| 1422 | |
| 1423 | retval = bprm_mm_init(bprm); |
| 1424 | if (retval) |
| 1425 | goto out_file; |
| 1426 | |
| 1427 | bprm->argc = count(argv, MAX_ARG_STRINGS); |
| 1428 | if ((retval = bprm->argc) < 0) |
| 1429 | goto out; |
| 1430 | |
| 1431 | bprm->envc = count(envp, MAX_ARG_STRINGS); |
| 1432 | if ((retval = bprm->envc) < 0) |
| 1433 | goto out; |
| 1434 | |
| 1435 | retval = prepare_binprm(bprm); |
| 1436 | if (retval < 0) |
| 1437 | goto out; |
| 1438 | |
| 1439 | retval = copy_strings_kernel(1, &bprm->filename, bprm); |
| 1440 | if (retval < 0) |
| 1441 | goto out; |
| 1442 | |
| 1443 | bprm->exec = bprm->p; |
| 1444 | retval = copy_strings(bprm->envc, envp, bprm); |
| 1445 | if (retval < 0) |
| 1446 | goto out; |
| 1447 | |
| 1448 | retval = copy_strings(bprm->argc, argv, bprm); |
| 1449 | if (retval < 0) |
| 1450 | goto out; |
| 1451 | |
| 1452 | retval = search_binary_handler(bprm,regs); |
| 1453 | if (retval < 0) |
| 1454 | goto out; |
| 1455 | |
| 1456 | /* execve succeeded */ |
| 1457 | current->fs->in_exec = 0; |
| 1458 | current->in_execve = 0; |
| 1459 | acct_update_integrals(current); |
| 1460 | free_bprm(bprm); |
| 1461 | if (displaced) |
| 1462 | put_files_struct(displaced); |
| 1463 | return retval; |
| 1464 | |
| 1465 | out: |
| 1466 | if (bprm->mm) { |
| 1467 | acct_arg_size(bprm, 0); |
| 1468 | mmput(bprm->mm); |
| 1469 | } |
| 1470 | |
| 1471 | out_file: |
| 1472 | if (bprm->file) { |
| 1473 | allow_write_access(bprm->file); |
| 1474 | fput(bprm->file); |
| 1475 | } |
| 1476 | |
| 1477 | out_unmark: |
| 1478 | if (clear_in_exec) |
| 1479 | current->fs->in_exec = 0; |
| 1480 | current->in_execve = 0; |
| 1481 | |
| 1482 | out_free: |
| 1483 | free_bprm(bprm); |
| 1484 | |
| 1485 | out_files: |
| 1486 | if (displaced) |
| 1487 | reset_files_struct(displaced); |
| 1488 | out_ret: |
| 1489 | return retval; |
| 1490 | } |
| 1491 | |
| 1492 | void set_binfmt(struct linux_binfmt *new) |
| 1493 | { |
| 1494 | struct mm_struct *mm = current->mm; |
| 1495 | |
| 1496 | if (mm->binfmt) |
| 1497 | module_put(mm->binfmt->module); |
| 1498 | |
| 1499 | mm->binfmt = new; |
| 1500 | if (new) |
| 1501 | __module_get(new->module); |
| 1502 | } |
| 1503 | |
| 1504 | EXPORT_SYMBOL(set_binfmt); |
| 1505 | |
| 1506 | static int expand_corename(struct core_name *cn) |
| 1507 | { |
| 1508 | char *old_corename = cn->corename; |
| 1509 | |
| 1510 | cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count); |
| 1511 | cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL); |
| 1512 | |
| 1513 | if (!cn->corename) { |
| 1514 | kfree(old_corename); |
| 1515 | return -ENOMEM; |
| 1516 | } |
| 1517 | |
| 1518 | return 0; |
| 1519 | } |
| 1520 | |
| 1521 | static int cn_printf(struct core_name *cn, const char *fmt, ...) |
| 1522 | { |
| 1523 | char *cur; |
| 1524 | int need; |
| 1525 | int ret; |
| 1526 | va_list arg; |
| 1527 | |
| 1528 | va_start(arg, fmt); |
| 1529 | need = vsnprintf(NULL, 0, fmt, arg); |
| 1530 | va_end(arg); |
| 1531 | |
| 1532 | if (likely(need < cn->size - cn->used - 1)) |
| 1533 | goto out_printf; |
| 1534 | |
| 1535 | ret = expand_corename(cn); |
| 1536 | if (ret) |
| 1537 | goto expand_fail; |
| 1538 | |
| 1539 | out_printf: |
| 1540 | cur = cn->corename + cn->used; |
| 1541 | va_start(arg, fmt); |
| 1542 | vsnprintf(cur, need + 1, fmt, arg); |
| 1543 | va_end(arg); |
| 1544 | cn->used += need; |
| 1545 | return 0; |
| 1546 | |
| 1547 | expand_fail: |
| 1548 | return ret; |
| 1549 | } |
| 1550 | |
| 1551 | /* format_corename will inspect the pattern parameter, and output a |
| 1552 | * name into corename, which must have space for at least |
| 1553 | * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator. |
| 1554 | */ |
| 1555 | static int format_corename(struct core_name *cn, long signr) |
| 1556 | { |
| 1557 | const struct cred *cred = current_cred(); |
| 1558 | const char *pat_ptr = core_pattern; |
| 1559 | int ispipe = (*pat_ptr == '|'); |
| 1560 | int pid_in_pattern = 0; |
| 1561 | int err = 0; |
| 1562 | |
| 1563 | cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count); |
| 1564 | cn->corename = kmalloc(cn->size, GFP_KERNEL); |
| 1565 | cn->used = 0; |
| 1566 | |
| 1567 | if (!cn->corename) |
| 1568 | return -ENOMEM; |
| 1569 | |
| 1570 | /* Repeat as long as we have more pattern to process and more output |
| 1571 | space */ |
| 1572 | while (*pat_ptr) { |
| 1573 | if (*pat_ptr != '%') { |
| 1574 | if (*pat_ptr == 0) |
| 1575 | goto out; |
| 1576 | err = cn_printf(cn, "%c", *pat_ptr++); |
| 1577 | } else { |
| 1578 | switch (*++pat_ptr) { |
| 1579 | /* single % at the end, drop that */ |
| 1580 | case 0: |
| 1581 | goto out; |
| 1582 | /* Double percent, output one percent */ |
| 1583 | case '%': |
| 1584 | err = cn_printf(cn, "%c", '%'); |
| 1585 | break; |
| 1586 | /* pid */ |
| 1587 | case 'p': |
| 1588 | pid_in_pattern = 1; |
| 1589 | err = cn_printf(cn, "%d", |
| 1590 | task_tgid_vnr(current)); |
| 1591 | break; |
| 1592 | /* uid */ |
| 1593 | case 'u': |
| 1594 | err = cn_printf(cn, "%d", cred->uid); |
| 1595 | break; |
| 1596 | /* gid */ |
| 1597 | case 'g': |
| 1598 | err = cn_printf(cn, "%d", cred->gid); |
| 1599 | break; |
| 1600 | /* signal that caused the coredump */ |
| 1601 | case 's': |
| 1602 | err = cn_printf(cn, "%ld", signr); |
| 1603 | break; |
| 1604 | /* UNIX time of coredump */ |
| 1605 | case 't': { |
| 1606 | struct timeval tv; |
| 1607 | do_gettimeofday(&tv); |
| 1608 | err = cn_printf(cn, "%lu", tv.tv_sec); |
| 1609 | break; |
| 1610 | } |
| 1611 | /* hostname */ |
| 1612 | case 'h': |
| 1613 | down_read(&uts_sem); |
| 1614 | err = cn_printf(cn, "%s", |
| 1615 | utsname()->nodename); |
| 1616 | up_read(&uts_sem); |
| 1617 | break; |
| 1618 | /* executable */ |
| 1619 | case 'e': |
| 1620 | err = cn_printf(cn, "%s", current->comm); |
| 1621 | break; |
| 1622 | /* core limit size */ |
| 1623 | case 'c': |
| 1624 | err = cn_printf(cn, "%lu", |
| 1625 | rlimit(RLIMIT_CORE)); |
| 1626 | break; |
| 1627 | default: |
| 1628 | break; |
| 1629 | } |
| 1630 | ++pat_ptr; |
| 1631 | } |
| 1632 | |
| 1633 | if (err) |
| 1634 | return err; |
| 1635 | } |
| 1636 | |
| 1637 | /* Backward compatibility with core_uses_pid: |
| 1638 | * |
| 1639 | * If core_pattern does not include a %p (as is the default) |
| 1640 | * and core_uses_pid is set, then .%pid will be appended to |
| 1641 | * the filename. Do not do this for piped commands. */ |
| 1642 | if (!ispipe && !pid_in_pattern && core_uses_pid) { |
| 1643 | err = cn_printf(cn, ".%d", task_tgid_vnr(current)); |
| 1644 | if (err) |
| 1645 | return err; |
| 1646 | } |
| 1647 | out: |
| 1648 | return ispipe; |
| 1649 | } |
| 1650 | |
| 1651 | static int zap_process(struct task_struct *start, int exit_code) |
| 1652 | { |
| 1653 | struct task_struct *t; |
| 1654 | int nr = 0; |
| 1655 | |
| 1656 | start->signal->flags = SIGNAL_GROUP_EXIT; |
| 1657 | start->signal->group_exit_code = exit_code; |
| 1658 | start->signal->group_stop_count = 0; |
| 1659 | |
| 1660 | t = start; |
| 1661 | do { |
| 1662 | task_clear_group_stop_pending(t); |
| 1663 | if (t != current && t->mm) { |
| 1664 | sigaddset(&t->pending.signal, SIGKILL); |
| 1665 | signal_wake_up(t, 1); |
| 1666 | nr++; |
| 1667 | } |
| 1668 | } while_each_thread(start, t); |
| 1669 | |
| 1670 | return nr; |
| 1671 | } |
| 1672 | |
| 1673 | static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm, |
| 1674 | struct core_state *core_state, int exit_code) |
| 1675 | { |
| 1676 | struct task_struct *g, *p; |
| 1677 | unsigned long flags; |
| 1678 | int nr = -EAGAIN; |
| 1679 | |
| 1680 | spin_lock_irq(&tsk->sighand->siglock); |
| 1681 | if (!signal_group_exit(tsk->signal)) { |
| 1682 | mm->core_state = core_state; |
| 1683 | nr = zap_process(tsk, exit_code); |
| 1684 | } |
| 1685 | spin_unlock_irq(&tsk->sighand->siglock); |
| 1686 | if (unlikely(nr < 0)) |
| 1687 | return nr; |
| 1688 | |
| 1689 | if (atomic_read(&mm->mm_users) == nr + 1) |
| 1690 | goto done; |
| 1691 | /* |
| 1692 | * We should find and kill all tasks which use this mm, and we should |
| 1693 | * count them correctly into ->nr_threads. We don't take tasklist |
| 1694 | * lock, but this is safe wrt: |
| 1695 | * |
| 1696 | * fork: |
| 1697 | * None of sub-threads can fork after zap_process(leader). All |
| 1698 | * processes which were created before this point should be |
| 1699 | * visible to zap_threads() because copy_process() adds the new |
| 1700 | * process to the tail of init_task.tasks list, and lock/unlock |
| 1701 | * of ->siglock provides a memory barrier. |
| 1702 | * |
| 1703 | * do_exit: |
| 1704 | * The caller holds mm->mmap_sem. This means that the task which |
| 1705 | * uses this mm can't pass exit_mm(), so it can't exit or clear |
| 1706 | * its ->mm. |
| 1707 | * |
| 1708 | * de_thread: |
| 1709 | * It does list_replace_rcu(&leader->tasks, ¤t->tasks), |
| 1710 | * we must see either old or new leader, this does not matter. |
| 1711 | * However, it can change p->sighand, so lock_task_sighand(p) |
| 1712 | * must be used. Since p->mm != NULL and we hold ->mmap_sem |
| 1713 | * it can't fail. |
| 1714 | * |
| 1715 | * Note also that "g" can be the old leader with ->mm == NULL |
| 1716 | * and already unhashed and thus removed from ->thread_group. |
| 1717 | * This is OK, __unhash_process()->list_del_rcu() does not |
| 1718 | * clear the ->next pointer, we will find the new leader via |
| 1719 | * next_thread(). |
| 1720 | */ |
| 1721 | rcu_read_lock(); |
| 1722 | for_each_process(g) { |
| 1723 | if (g == tsk->group_leader) |
| 1724 | continue; |
| 1725 | if (g->flags & PF_KTHREAD) |
| 1726 | continue; |
| 1727 | p = g; |
| 1728 | do { |
| 1729 | if (p->mm) { |
| 1730 | if (unlikely(p->mm == mm)) { |
| 1731 | lock_task_sighand(p, &flags); |
| 1732 | nr += zap_process(p, exit_code); |
| 1733 | unlock_task_sighand(p, &flags); |
| 1734 | } |
| 1735 | break; |
| 1736 | } |
| 1737 | } while_each_thread(g, p); |
| 1738 | } |
| 1739 | rcu_read_unlock(); |
| 1740 | done: |
| 1741 | atomic_set(&core_state->nr_threads, nr); |
| 1742 | return nr; |
| 1743 | } |
| 1744 | |
| 1745 | static int coredump_wait(int exit_code, struct core_state *core_state) |
| 1746 | { |
| 1747 | struct task_struct *tsk = current; |
| 1748 | struct mm_struct *mm = tsk->mm; |
| 1749 | struct completion *vfork_done; |
| 1750 | int core_waiters = -EBUSY; |
| 1751 | |
| 1752 | init_completion(&core_state->startup); |
| 1753 | core_state->dumper.task = tsk; |
| 1754 | core_state->dumper.next = NULL; |
| 1755 | |
| 1756 | down_write(&mm->mmap_sem); |
| 1757 | if (!mm->core_state) |
| 1758 | core_waiters = zap_threads(tsk, mm, core_state, exit_code); |
| 1759 | up_write(&mm->mmap_sem); |
| 1760 | |
| 1761 | if (unlikely(core_waiters < 0)) |
| 1762 | goto fail; |
| 1763 | |
| 1764 | /* |
| 1765 | * Make sure nobody is waiting for us to release the VM, |
| 1766 | * otherwise we can deadlock when we wait on each other |
| 1767 | */ |
| 1768 | vfork_done = tsk->vfork_done; |
| 1769 | if (vfork_done) { |
| 1770 | tsk->vfork_done = NULL; |
| 1771 | complete(vfork_done); |
| 1772 | } |
| 1773 | |
| 1774 | if (core_waiters) |
| 1775 | wait_for_completion(&core_state->startup); |
| 1776 | fail: |
| 1777 | return core_waiters; |
| 1778 | } |
| 1779 | |
| 1780 | static void coredump_finish(struct mm_struct *mm) |
| 1781 | { |
| 1782 | struct core_thread *curr, *next; |
| 1783 | struct task_struct *task; |
| 1784 | |
| 1785 | next = mm->core_state->dumper.next; |
| 1786 | while ((curr = next) != NULL) { |
| 1787 | next = curr->next; |
| 1788 | task = curr->task; |
| 1789 | /* |
| 1790 | * see exit_mm(), curr->task must not see |
| 1791 | * ->task == NULL before we read ->next. |
| 1792 | */ |
| 1793 | smp_mb(); |
| 1794 | curr->task = NULL; |
| 1795 | wake_up_process(task); |
| 1796 | } |
| 1797 | |
| 1798 | mm->core_state = NULL; |
| 1799 | } |
| 1800 | |
| 1801 | /* |
| 1802 | * set_dumpable converts traditional three-value dumpable to two flags and |
| 1803 | * stores them into mm->flags. It modifies lower two bits of mm->flags, but |
| 1804 | * these bits are not changed atomically. So get_dumpable can observe the |
| 1805 | * intermediate state. To avoid doing unexpected behavior, get get_dumpable |
| 1806 | * return either old dumpable or new one by paying attention to the order of |
| 1807 | * modifying the bits. |
| 1808 | * |
| 1809 | * dumpable | mm->flags (binary) |
| 1810 | * old new | initial interim final |
| 1811 | * ---------+----------------------- |
| 1812 | * 0 1 | 00 01 01 |
| 1813 | * 0 2 | 00 10(*) 11 |
| 1814 | * 1 0 | 01 00 00 |
| 1815 | * 1 2 | 01 11 11 |
| 1816 | * 2 0 | 11 10(*) 00 |
| 1817 | * 2 1 | 11 11 01 |
| 1818 | * |
| 1819 | * (*) get_dumpable regards interim value of 10 as 11. |
| 1820 | */ |
| 1821 | void set_dumpable(struct mm_struct *mm, int value) |
| 1822 | { |
| 1823 | switch (value) { |
| 1824 | case 0: |
| 1825 | clear_bit(MMF_DUMPABLE, &mm->flags); |
| 1826 | smp_wmb(); |
| 1827 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
| 1828 | break; |
| 1829 | case 1: |
| 1830 | set_bit(MMF_DUMPABLE, &mm->flags); |
| 1831 | smp_wmb(); |
| 1832 | clear_bit(MMF_DUMP_SECURELY, &mm->flags); |
| 1833 | break; |
| 1834 | case 2: |
| 1835 | set_bit(MMF_DUMP_SECURELY, &mm->flags); |
| 1836 | smp_wmb(); |
| 1837 | set_bit(MMF_DUMPABLE, &mm->flags); |
| 1838 | break; |
| 1839 | } |
| 1840 | } |
| 1841 | |
| 1842 | static int __get_dumpable(unsigned long mm_flags) |
| 1843 | { |
| 1844 | int ret; |
| 1845 | |
| 1846 | ret = mm_flags & MMF_DUMPABLE_MASK; |
| 1847 | return (ret >= 2) ? 2 : ret; |
| 1848 | } |
| 1849 | |
| 1850 | int get_dumpable(struct mm_struct *mm) |
| 1851 | { |
| 1852 | return __get_dumpable(mm->flags); |
| 1853 | } |
| 1854 | |
| 1855 | static void wait_for_dump_helpers(struct file *file) |
| 1856 | { |
| 1857 | struct pipe_inode_info *pipe; |
| 1858 | |
| 1859 | pipe = file->f_path.dentry->d_inode->i_pipe; |
| 1860 | |
| 1861 | pipe_lock(pipe); |
| 1862 | pipe->readers++; |
| 1863 | pipe->writers--; |
| 1864 | |
| 1865 | while ((pipe->readers > 1) && (!signal_pending(current))) { |
| 1866 | wake_up_interruptible_sync(&pipe->wait); |
| 1867 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
| 1868 | pipe_wait(pipe); |
| 1869 | } |
| 1870 | |
| 1871 | pipe->readers--; |
| 1872 | pipe->writers++; |
| 1873 | pipe_unlock(pipe); |
| 1874 | |
| 1875 | } |
| 1876 | |
| 1877 | |
| 1878 | /* |
| 1879 | * umh_pipe_setup |
| 1880 | * helper function to customize the process used |
| 1881 | * to collect the core in userspace. Specifically |
| 1882 | * it sets up a pipe and installs it as fd 0 (stdin) |
| 1883 | * for the process. Returns 0 on success, or |
| 1884 | * PTR_ERR on failure. |
| 1885 | * Note that it also sets the core limit to 1. This |
| 1886 | * is a special value that we use to trap recursive |
| 1887 | * core dumps |
| 1888 | */ |
| 1889 | static int umh_pipe_setup(struct subprocess_info *info) |
| 1890 | { |
| 1891 | struct file *rp, *wp; |
| 1892 | struct fdtable *fdt; |
| 1893 | struct coredump_params *cp = (struct coredump_params *)info->data; |
| 1894 | struct files_struct *cf = current->files; |
| 1895 | |
| 1896 | wp = create_write_pipe(0); |
| 1897 | if (IS_ERR(wp)) |
| 1898 | return PTR_ERR(wp); |
| 1899 | |
| 1900 | rp = create_read_pipe(wp, 0); |
| 1901 | if (IS_ERR(rp)) { |
| 1902 | free_write_pipe(wp); |
| 1903 | return PTR_ERR(rp); |
| 1904 | } |
| 1905 | |
| 1906 | cp->file = wp; |
| 1907 | |
| 1908 | sys_close(0); |
| 1909 | fd_install(0, rp); |
| 1910 | spin_lock(&cf->file_lock); |
| 1911 | fdt = files_fdtable(cf); |
| 1912 | FD_SET(0, fdt->open_fds); |
| 1913 | FD_CLR(0, fdt->close_on_exec); |
| 1914 | spin_unlock(&cf->file_lock); |
| 1915 | |
| 1916 | /* and disallow core files too */ |
| 1917 | current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1}; |
| 1918 | |
| 1919 | return 0; |
| 1920 | } |
| 1921 | |
| 1922 | void do_coredump(long signr, int exit_code, struct pt_regs *regs) |
| 1923 | { |
| 1924 | struct core_state core_state; |
| 1925 | struct core_name cn; |
| 1926 | struct mm_struct *mm = current->mm; |
| 1927 | struct linux_binfmt * binfmt; |
| 1928 | const struct cred *old_cred; |
| 1929 | struct cred *cred; |
| 1930 | int retval = 0; |
| 1931 | int flag = 0; |
| 1932 | int ispipe; |
| 1933 | static atomic_t core_dump_count = ATOMIC_INIT(0); |
| 1934 | struct coredump_params cprm = { |
| 1935 | .signr = signr, |
| 1936 | .regs = regs, |
| 1937 | .limit = rlimit(RLIMIT_CORE), |
| 1938 | /* |
| 1939 | * We must use the same mm->flags while dumping core to avoid |
| 1940 | * inconsistency of bit flags, since this flag is not protected |
| 1941 | * by any locks. |
| 1942 | */ |
| 1943 | .mm_flags = mm->flags, |
| 1944 | }; |
| 1945 | |
| 1946 | audit_core_dumps(signr); |
| 1947 | |
| 1948 | binfmt = mm->binfmt; |
| 1949 | if (!binfmt || !binfmt->core_dump) |
| 1950 | goto fail; |
| 1951 | if (!__get_dumpable(cprm.mm_flags)) |
| 1952 | goto fail; |
| 1953 | |
| 1954 | cred = prepare_creds(); |
| 1955 | if (!cred) |
| 1956 | goto fail; |
| 1957 | /* |
| 1958 | * We cannot trust fsuid as being the "true" uid of the |
| 1959 | * process nor do we know its entire history. We only know it |
| 1960 | * was tainted so we dump it as root in mode 2. |
| 1961 | */ |
| 1962 | if (__get_dumpable(cprm.mm_flags) == 2) { |
| 1963 | /* Setuid core dump mode */ |
| 1964 | flag = O_EXCL; /* Stop rewrite attacks */ |
| 1965 | cred->fsuid = 0; /* Dump root private */ |
| 1966 | } |
| 1967 | |
| 1968 | retval = coredump_wait(exit_code, &core_state); |
| 1969 | if (retval < 0) |
| 1970 | goto fail_creds; |
| 1971 | |
| 1972 | old_cred = override_creds(cred); |
| 1973 | |
| 1974 | /* |
| 1975 | * Clear any false indication of pending signals that might |
| 1976 | * be seen by the filesystem code called to write the core file. |
| 1977 | */ |
| 1978 | clear_thread_flag(TIF_SIGPENDING); |
| 1979 | |
| 1980 | ispipe = format_corename(&cn, signr); |
| 1981 | |
| 1982 | if (ispipe == -ENOMEM) { |
| 1983 | printk(KERN_WARNING "format_corename failed\n"); |
| 1984 | printk(KERN_WARNING "Aborting core\n"); |
| 1985 | goto fail_corename; |
| 1986 | } |
| 1987 | |
| 1988 | if (ispipe) { |
| 1989 | int dump_count; |
| 1990 | char **helper_argv; |
| 1991 | |
| 1992 | if (cprm.limit == 1) { |
| 1993 | /* |
| 1994 | * Normally core limits are irrelevant to pipes, since |
| 1995 | * we're not writing to the file system, but we use |
| 1996 | * cprm.limit of 1 here as a speacial value. Any |
| 1997 | * non-1 limit gets set to RLIM_INFINITY below, but |
| 1998 | * a limit of 0 skips the dump. This is a consistent |
| 1999 | * way to catch recursive crashes. We can still crash |
| 2000 | * if the core_pattern binary sets RLIM_CORE = !1 |
| 2001 | * but it runs as root, and can do lots of stupid things |
| 2002 | * Note that we use task_tgid_vnr here to grab the pid |
| 2003 | * of the process group leader. That way we get the |
| 2004 | * right pid if a thread in a multi-threaded |
| 2005 | * core_pattern process dies. |
| 2006 | */ |
| 2007 | printk(KERN_WARNING |
| 2008 | "Process %d(%s) has RLIMIT_CORE set to 1\n", |
| 2009 | task_tgid_vnr(current), current->comm); |
| 2010 | printk(KERN_WARNING "Aborting core\n"); |
| 2011 | goto fail_unlock; |
| 2012 | } |
| 2013 | cprm.limit = RLIM_INFINITY; |
| 2014 | |
| 2015 | dump_count = atomic_inc_return(&core_dump_count); |
| 2016 | if (core_pipe_limit && (core_pipe_limit < dump_count)) { |
| 2017 | printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n", |
| 2018 | task_tgid_vnr(current), current->comm); |
| 2019 | printk(KERN_WARNING "Skipping core dump\n"); |
| 2020 | goto fail_dropcount; |
| 2021 | } |
| 2022 | |
| 2023 | helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL); |
| 2024 | if (!helper_argv) { |
| 2025 | printk(KERN_WARNING "%s failed to allocate memory\n", |
| 2026 | __func__); |
| 2027 | goto fail_dropcount; |
| 2028 | } |
| 2029 | |
| 2030 | retval = call_usermodehelper_fns(helper_argv[0], helper_argv, |
| 2031 | NULL, UMH_WAIT_EXEC, umh_pipe_setup, |
| 2032 | NULL, &cprm); |
| 2033 | argv_free(helper_argv); |
| 2034 | if (retval) { |
| 2035 | printk(KERN_INFO "Core dump to %s pipe failed\n", |
| 2036 | cn.corename); |
| 2037 | goto close_fail; |
| 2038 | } |
| 2039 | } else { |
| 2040 | struct inode *inode; |
| 2041 | |
| 2042 | if (cprm.limit < binfmt->min_coredump) |
| 2043 | goto fail_unlock; |
| 2044 | |
| 2045 | cprm.file = filp_open(cn.corename, |
| 2046 | O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, |
| 2047 | 0600); |
| 2048 | if (IS_ERR(cprm.file)) |
| 2049 | goto fail_unlock; |
| 2050 | |
| 2051 | inode = cprm.file->f_path.dentry->d_inode; |
| 2052 | if (inode->i_nlink > 1) |
| 2053 | goto close_fail; |
| 2054 | if (d_unhashed(cprm.file->f_path.dentry)) |
| 2055 | goto close_fail; |
| 2056 | /* |
| 2057 | * AK: actually i see no reason to not allow this for named |
| 2058 | * pipes etc, but keep the previous behaviour for now. |
| 2059 | */ |
| 2060 | if (!S_ISREG(inode->i_mode)) |
| 2061 | goto close_fail; |
| 2062 | /* |
| 2063 | * Dont allow local users get cute and trick others to coredump |
| 2064 | * into their pre-created files. |
| 2065 | */ |
| 2066 | if (inode->i_uid != current_fsuid()) |
| 2067 | goto close_fail; |
| 2068 | if (!cprm.file->f_op || !cprm.file->f_op->write) |
| 2069 | goto close_fail; |
| 2070 | if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file)) |
| 2071 | goto close_fail; |
| 2072 | } |
| 2073 | |
| 2074 | retval = binfmt->core_dump(&cprm); |
| 2075 | if (retval) |
| 2076 | current->signal->group_exit_code |= 0x80; |
| 2077 | |
| 2078 | if (ispipe && core_pipe_limit) |
| 2079 | wait_for_dump_helpers(cprm.file); |
| 2080 | close_fail: |
| 2081 | if (cprm.file) |
| 2082 | filp_close(cprm.file, NULL); |
| 2083 | fail_dropcount: |
| 2084 | if (ispipe) |
| 2085 | atomic_dec(&core_dump_count); |
| 2086 | fail_unlock: |
| 2087 | kfree(cn.corename); |
| 2088 | fail_corename: |
| 2089 | coredump_finish(mm); |
| 2090 | revert_creds(old_cred); |
| 2091 | fail_creds: |
| 2092 | put_cred(cred); |
| 2093 | fail: |
| 2094 | return; |
| 2095 | } |
| 2096 | |
| 2097 | /* |
| 2098 | * Core dumping helper functions. These are the only things you should |
| 2099 | * do on a core-file: use only these functions to write out all the |
| 2100 | * necessary info. |
| 2101 | */ |
| 2102 | int dump_write(struct file *file, const void *addr, int nr) |
| 2103 | { |
| 2104 | return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr; |
| 2105 | } |
| 2106 | EXPORT_SYMBOL(dump_write); |
| 2107 | |
| 2108 | int dump_seek(struct file *file, loff_t off) |
| 2109 | { |
| 2110 | int ret = 1; |
| 2111 | |
| 2112 | if (file->f_op->llseek && file->f_op->llseek != no_llseek) { |
| 2113 | if (file->f_op->llseek(file, off, SEEK_CUR) < 0) |
| 2114 | return 0; |
| 2115 | } else { |
| 2116 | char *buf = (char *)get_zeroed_page(GFP_KERNEL); |
| 2117 | |
| 2118 | if (!buf) |
| 2119 | return 0; |
| 2120 | while (off > 0) { |
| 2121 | unsigned long n = off; |
| 2122 | |
| 2123 | if (n > PAGE_SIZE) |
| 2124 | n = PAGE_SIZE; |
| 2125 | if (!dump_write(file, buf, n)) { |
| 2126 | ret = 0; |
| 2127 | break; |
| 2128 | } |
| 2129 | off -= n; |
| 2130 | } |
| 2131 | free_page((unsigned long)buf); |
| 2132 | } |
| 2133 | return ret; |
| 2134 | } |
| 2135 | EXPORT_SYMBOL(dump_seek); |