1 /* 2 * linux/kernel/fork.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 /* 8 * 'fork.c' contains the help-routines for the 'fork' system call 9 * (see also entry.S and others). 10 * Fork is rather simple, once you get the hang of it, but the memory 11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' 12 */ 13 14 #include <linux/slab.h> 15 #include <linux/init.h> 16 #include <linux/unistd.h> 17 #include <linux/module.h> 18 #include <linux/vmalloc.h> 19 #include <linux/completion.h> 20 #include <linux/personality.h> 21 #include <linux/mempolicy.h> 22 #include <linux/sem.h> 23 #include <linux/file.h> 24 #include <linux/fdtable.h> 25 #include <linux/iocontext.h> 26 #include <linux/key.h> 27 #include <linux/binfmts.h> 28 #include <linux/mman.h> 29 #include <linux/mmu_notifier.h> 30 #include <linux/fs.h> 31 #include <linux/mm.h> 32 #include <linux/vmacache.h> 33 #include <linux/nsproxy.h> 34 #include <linux/capability.h> 35 #include <linux/cpu.h> 36 #include <linux/cgroup.h> 37 #include <linux/security.h> 38 #include <linux/hugetlb.h> 39 #include <linux/seccomp.h> 40 #include <linux/swap.h> 41 #include <linux/syscalls.h> 42 #include <linux/jiffies.h> 43 #include <linux/futex.h> 44 #include <linux/compat.h> 45 #include <linux/kthread.h> 46 #include <linux/task_io_accounting_ops.h> 47 #include <linux/rcupdate.h> 48 #include <linux/ptrace.h> 49 #include <linux/mount.h> 50 #include <linux/audit.h> 51 #include <linux/memcontrol.h> 52 #include <linux/ftrace.h> 53 #include <linux/proc_fs.h> 54 #include <linux/profile.h> 55 #include <linux/rmap.h> 56 #include <linux/ksm.h> 57 #include <linux/acct.h> 58 #include <linux/tsacct_kern.h> 59 #include <linux/cn_proc.h> 60 #include <linux/freezer.h> 61 #include <linux/delayacct.h> 62 #include <linux/taskstats_kern.h> 63 #include <linux/random.h> 64 #include <linux/tty.h> 65 #include <linux/blkdev.h> 66 #include <linux/fs_struct.h> 67 #include <linux/magic.h> 68 #include <linux/perf_event.h> 69 #include <linux/posix-timers.h> 70 #include <linux/user-return-notifier.h> 71 #include <linux/oom.h> 72 #include <linux/khugepaged.h> 73 #include <linux/signalfd.h> 74 #include <linux/uprobes.h> 75 #include <linux/aio.h> 76 #include <linux/compiler.h> 77 #include <linux/sysctl.h> 78 #include <linux/kcov.h> 79 80 #include <asm/pgtable.h> 81 #include <asm/pgalloc.h> 82 #include <asm/uaccess.h> 83 #include <asm/mmu_context.h> 84 #include <asm/cacheflush.h> 85 #include <asm/tlbflush.h> 86 87 #include <trace/events/sched.h> 88 89 #define CREATE_TRACE_POINTS 90 #include <trace/events/task.h> 91 92 /* 93 * Minimum number of threads to boot the kernel 94 */ 95 #define MIN_THREADS 20 96 97 /* 98 * Maximum number of threads 99 */ 100 #define MAX_THREADS FUTEX_TID_MASK 101 102 /* 103 * Protected counters by write_lock_irq(&tasklist_lock) 104 */ 105 unsigned long total_forks; /* Handle normal Linux uptimes. */ 106 int nr_threads; /* The idle threads do not count.. */ 107 108 int max_threads; /* tunable limit on nr_threads */ 109 110 DEFINE_PER_CPU(unsigned long, process_counts) = 0; 111 112 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ 113 114 #ifdef CONFIG_PROVE_RCU 115 int lockdep_tasklist_lock_is_held(void) 116 { 117 return lockdep_is_held(&tasklist_lock); 118 } 119 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); 120 #endif /* #ifdef CONFIG_PROVE_RCU */ 121 122 int nr_processes(void) 123 { 124 int cpu; 125 int total = 0; 126 127 for_each_possible_cpu(cpu) 128 total += per_cpu(process_counts, cpu); 129 130 return total; 131 } 132 133 void __weak arch_release_task_struct(struct task_struct *tsk) 134 { 135 } 136 137 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 138 static struct kmem_cache *task_struct_cachep; 139 140 static inline struct task_struct *alloc_task_struct_node(int node) 141 { 142 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); 143 } 144 145 static inline void free_task_struct(struct task_struct *tsk) 146 { 147 kmem_cache_free(task_struct_cachep, tsk); 148 } 149 #endif 150 151 void __weak arch_release_thread_info(struct thread_info *ti) 152 { 153 } 154 155 #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR 156 157 /* 158 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a 159 * kmemcache based allocator. 160 */ 161 # if THREAD_SIZE >= PAGE_SIZE 162 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, 163 int node) 164 { 165 struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP, 166 THREAD_SIZE_ORDER); 167 168 if (page) 169 memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK, 170 1 << THREAD_SIZE_ORDER); 171 172 return page ? page_address(page) : NULL; 173 } 174 175 static inline void free_thread_info(struct thread_info *ti) 176 { 177 struct page *page = virt_to_page(ti); 178 179 memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK, 180 -(1 << THREAD_SIZE_ORDER)); 181 __free_kmem_pages(page, THREAD_SIZE_ORDER); 182 } 183 # else 184 static struct kmem_cache *thread_info_cache; 185 186 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, 187 int node) 188 { 189 return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node); 190 } 191 192 static void free_thread_info(struct thread_info *ti) 193 { 194 kmem_cache_free(thread_info_cache, ti); 195 } 196 197 void thread_info_cache_init(void) 198 { 199 thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE, 200 THREAD_SIZE, 0, NULL); 201 BUG_ON(thread_info_cache == NULL); 202 } 203 # endif 204 #endif 205 206 /* SLAB cache for signal_struct structures (tsk->signal) */ 207 static struct kmem_cache *signal_cachep; 208 209 /* SLAB cache for sighand_struct structures (tsk->sighand) */ 210 struct kmem_cache *sighand_cachep; 211 212 /* SLAB cache for files_struct structures (tsk->files) */ 213 struct kmem_cache *files_cachep; 214 215 /* SLAB cache for fs_struct structures (tsk->fs) */ 216 struct kmem_cache *fs_cachep; 217 218 /* SLAB cache for vm_area_struct structures */ 219 struct kmem_cache *vm_area_cachep; 220 221 /* SLAB cache for mm_struct structures (tsk->mm) */ 222 static struct kmem_cache *mm_cachep; 223 224 static void account_kernel_stack(struct thread_info *ti, int account) 225 { 226 struct zone *zone = page_zone(virt_to_page(ti)); 227 228 mod_zone_page_state(zone, NR_KERNEL_STACK, account); 229 } 230 231 void free_task(struct task_struct *tsk) 232 { 233 account_kernel_stack(tsk->stack, -1); 234 arch_release_thread_info(tsk->stack); 235 free_thread_info(tsk->stack); 236 rt_mutex_debug_task_free(tsk); 237 ftrace_graph_exit_task(tsk); 238 put_seccomp_filter(tsk); 239 arch_release_task_struct(tsk); 240 free_task_struct(tsk); 241 } 242 EXPORT_SYMBOL(free_task); 243 244 static inline void free_signal_struct(struct signal_struct *sig) 245 { 246 taskstats_tgid_free(sig); 247 sched_autogroup_exit(sig); 248 kmem_cache_free(signal_cachep, sig); 249 } 250 251 static inline void put_signal_struct(struct signal_struct *sig) 252 { 253 if (atomic_dec_and_test(&sig->sigcnt)) 254 free_signal_struct(sig); 255 } 256 257 void __put_task_struct(struct task_struct *tsk) 258 { 259 WARN_ON(!tsk->exit_state); 260 WARN_ON(atomic_read(&tsk->usage)); 261 WARN_ON(tsk == current); 262 263 cgroup_free(tsk); 264 task_numa_free(tsk); 265 security_task_free(tsk); 266 exit_creds(tsk); 267 delayacct_tsk_free(tsk); 268 put_signal_struct(tsk->signal); 269 270 if (!profile_handoff_task(tsk)) 271 free_task(tsk); 272 } 273 EXPORT_SYMBOL_GPL(__put_task_struct); 274 275 void __init __weak arch_task_cache_init(void) { } 276 277 /* 278 * set_max_threads 279 */ 280 static void set_max_threads(unsigned int max_threads_suggested) 281 { 282 u64 threads; 283 284 /* 285 * The number of threads shall be limited such that the thread 286 * structures may only consume a small part of the available memory. 287 */ 288 if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64) 289 threads = MAX_THREADS; 290 else 291 threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE, 292 (u64) THREAD_SIZE * 8UL); 293 294 if (threads > max_threads_suggested) 295 threads = max_threads_suggested; 296 297 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS); 298 } 299 300 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT 301 /* Initialized by the architecture: */ 302 int arch_task_struct_size __read_mostly; 303 #endif 304 305 void __init fork_init(void) 306 { 307 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR 308 #ifndef ARCH_MIN_TASKALIGN 309 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES 310 #endif 311 /* create a slab on which task_structs can be allocated */ 312 task_struct_cachep = kmem_cache_create("task_struct", 313 arch_task_struct_size, ARCH_MIN_TASKALIGN, 314 SLAB_PANIC|SLAB_NOTRACK|SLAB_ACCOUNT, NULL); 315 #endif 316 317 /* do the arch specific task caches init */ 318 arch_task_cache_init(); 319 320 set_max_threads(MAX_THREADS); 321 322 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; 323 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; 324 init_task.signal->rlim[RLIMIT_SIGPENDING] = 325 init_task.signal->rlim[RLIMIT_NPROC]; 326 } 327 328 int __weak arch_dup_task_struct(struct task_struct *dst, 329 struct task_struct *src) 330 { 331 *dst = *src; 332 return 0; 333 } 334 335 void set_task_stack_end_magic(struct task_struct *tsk) 336 { 337 unsigned long *stackend; 338 339 stackend = end_of_stack(tsk); 340 *stackend = STACK_END_MAGIC; /* for overflow detection */ 341 } 342 343 static struct task_struct *dup_task_struct(struct task_struct *orig, int node) 344 { 345 struct task_struct *tsk; 346 struct thread_info *ti; 347 int err; 348 349 if (node == NUMA_NO_NODE) 350 node = tsk_fork_get_node(orig); 351 tsk = alloc_task_struct_node(node); 352 if (!tsk) 353 return NULL; 354 355 ti = alloc_thread_info_node(tsk, node); 356 if (!ti) 357 goto free_tsk; 358 359 err = arch_dup_task_struct(tsk, orig); 360 if (err) 361 goto free_ti; 362 363 tsk->stack = ti; 364 #ifdef CONFIG_SECCOMP 365 /* 366 * We must handle setting up seccomp filters once we're under 367 * the sighand lock in case orig has changed between now and 368 * then. Until then, filter must be NULL to avoid messing up 369 * the usage counts on the error path calling free_task. 370 */ 371 tsk->seccomp.filter = NULL; 372 #endif 373 374 setup_thread_stack(tsk, orig); 375 clear_user_return_notifier(tsk); 376 clear_tsk_need_resched(tsk); 377 set_task_stack_end_magic(tsk); 378 379 #ifdef CONFIG_CC_STACKPROTECTOR 380 tsk->stack_canary = get_random_int(); 381 #endif 382 383 /* 384 * One for us, one for whoever does the "release_task()" (usually 385 * parent) 386 */ 387 atomic_set(&tsk->usage, 2); 388 #ifdef CONFIG_BLK_DEV_IO_TRACE 389 tsk->btrace_seq = 0; 390 #endif 391 tsk->splice_pipe = NULL; 392 tsk->task_frag.page = NULL; 393 tsk->wake_q.next = NULL; 394 395 account_kernel_stack(ti, 1); 396 397 kcov_task_init(tsk); 398 399 return tsk; 400 401 free_ti: 402 free_thread_info(ti); 403 free_tsk: 404 free_task_struct(tsk); 405 return NULL; 406 } 407 408 #ifdef CONFIG_MMU 409 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 410 { 411 struct vm_area_struct *mpnt, *tmp, *prev, **pprev; 412 struct rb_node **rb_link, *rb_parent; 413 int retval; 414 unsigned long charge; 415 416 uprobe_start_dup_mmap(); 417 if (down_write_killable(&oldmm->mmap_sem)) { 418 retval = -EINTR; 419 goto fail_uprobe_end; 420 } 421 flush_cache_dup_mm(oldmm); 422 uprobe_dup_mmap(oldmm, mm); 423 /* 424 * Not linked in yet - no deadlock potential: 425 */ 426 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); 427 428 /* No ordering required: file already has been exposed. */ 429 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 430 431 mm->total_vm = oldmm->total_vm; 432 mm->data_vm = oldmm->data_vm; 433 mm->exec_vm = oldmm->exec_vm; 434 mm->stack_vm = oldmm->stack_vm; 435 436 rb_link = &mm->mm_rb.rb_node; 437 rb_parent = NULL; 438 pprev = &mm->mmap; 439 retval = ksm_fork(mm, oldmm); 440 if (retval) 441 goto out; 442 retval = khugepaged_fork(mm, oldmm); 443 if (retval) 444 goto out; 445 446 prev = NULL; 447 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { 448 struct file *file; 449 450 if (mpnt->vm_flags & VM_DONTCOPY) { 451 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); 452 continue; 453 } 454 charge = 0; 455 if (mpnt->vm_flags & VM_ACCOUNT) { 456 unsigned long len = vma_pages(mpnt); 457 458 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ 459 goto fail_nomem; 460 charge = len; 461 } 462 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 463 if (!tmp) 464 goto fail_nomem; 465 *tmp = *mpnt; 466 INIT_LIST_HEAD(&tmp->anon_vma_chain); 467 retval = vma_dup_policy(mpnt, tmp); 468 if (retval) 469 goto fail_nomem_policy; 470 tmp->vm_mm = mm; 471 if (anon_vma_fork(tmp, mpnt)) 472 goto fail_nomem_anon_vma_fork; 473 tmp->vm_flags &= 474 ~(VM_LOCKED|VM_LOCKONFAULT|VM_UFFD_MISSING|VM_UFFD_WP); 475 tmp->vm_next = tmp->vm_prev = NULL; 476 tmp->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; 477 file = tmp->vm_file; 478 if (file) { 479 struct inode *inode = file_inode(file); 480 struct address_space *mapping = file->f_mapping; 481 482 get_file(file); 483 if (tmp->vm_flags & VM_DENYWRITE) 484 atomic_dec(&inode->i_writecount); 485 i_mmap_lock_write(mapping); 486 if (tmp->vm_flags & VM_SHARED) 487 atomic_inc(&mapping->i_mmap_writable); 488 flush_dcache_mmap_lock(mapping); 489 /* insert tmp into the share list, just after mpnt */ 490 vma_interval_tree_insert_after(tmp, mpnt, 491 &mapping->i_mmap); 492 flush_dcache_mmap_unlock(mapping); 493 i_mmap_unlock_write(mapping); 494 } 495 496 /* 497 * Clear hugetlb-related page reserves for children. This only 498 * affects MAP_PRIVATE mappings. Faults generated by the child 499 * are not guaranteed to succeed, even if read-only 500 */ 501 if (is_vm_hugetlb_page(tmp)) 502 reset_vma_resv_huge_pages(tmp); 503 504 /* 505 * Link in the new vma and copy the page table entries. 506 */ 507 *pprev = tmp; 508 pprev = &tmp->vm_next; 509 tmp->vm_prev = prev; 510 prev = tmp; 511 512 __vma_link_rb(mm, tmp, rb_link, rb_parent); 513 rb_link = &tmp->vm_rb.rb_right; 514 rb_parent = &tmp->vm_rb; 515 516 mm->map_count++; 517 retval = copy_page_range(mm, oldmm, mpnt); 518 519 if (tmp->vm_ops && tmp->vm_ops->open) 520 tmp->vm_ops->open(tmp); 521 522 if (retval) 523 goto out; 524 } 525 /* a new mm has just been created */ 526 arch_dup_mmap(oldmm, mm); 527 retval = 0; 528 out: 529 up_write(&mm->mmap_sem); 530 flush_tlb_mm(oldmm); 531 up_write(&oldmm->mmap_sem); 532 fail_uprobe_end: 533 uprobe_end_dup_mmap(); 534 return retval; 535 fail_nomem_anon_vma_fork: 536 mpol_put(vma_policy(tmp)); 537 fail_nomem_policy: 538 kmem_cache_free(vm_area_cachep, tmp); 539 fail_nomem: 540 retval = -ENOMEM; 541 vm_unacct_memory(charge); 542 goto out; 543 } 544 545 static inline int mm_alloc_pgd(struct mm_struct *mm) 546 { 547 mm->pgd = pgd_alloc(mm); 548 if (unlikely(!mm->pgd)) 549 return -ENOMEM; 550 return 0; 551 } 552 553 static inline void mm_free_pgd(struct mm_struct *mm) 554 { 555 pgd_free(mm, mm->pgd); 556 } 557 #else 558 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) 559 { 560 down_write(&oldmm->mmap_sem); 561 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm)); 562 up_write(&oldmm->mmap_sem); 563 return 0; 564 } 565 #define mm_alloc_pgd(mm) (0) 566 #define mm_free_pgd(mm) 567 #endif /* CONFIG_MMU */ 568 569 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); 570 571 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) 572 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) 573 574 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; 575 576 static int __init coredump_filter_setup(char *s) 577 { 578 default_dump_filter = 579 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & 580 MMF_DUMP_FILTER_MASK; 581 return 1; 582 } 583 584 __setup("coredump_filter=", coredump_filter_setup); 585 586 #include <linux/init_task.h> 587 588 static void mm_init_aio(struct mm_struct *mm) 589 { 590 #ifdef CONFIG_AIO 591 spin_lock_init(&mm->ioctx_lock); 592 mm->ioctx_table = NULL; 593 #endif 594 } 595 596 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p) 597 { 598 #ifdef CONFIG_MEMCG 599 mm->owner = p; 600 #endif 601 } 602 603 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) 604 { 605 mm->mmap = NULL; 606 mm->mm_rb = RB_ROOT; 607 mm->vmacache_seqnum = 0; 608 atomic_set(&mm->mm_users, 1); 609 atomic_set(&mm->mm_count, 1); 610 init_rwsem(&mm->mmap_sem); 611 INIT_LIST_HEAD(&mm->mmlist); 612 mm->core_state = NULL; 613 atomic_long_set(&mm->nr_ptes, 0); 614 mm_nr_pmds_init(mm); 615 mm->map_count = 0; 616 mm->locked_vm = 0; 617 mm->pinned_vm = 0; 618 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); 619 spin_lock_init(&mm->page_table_lock); 620 mm_init_cpumask(mm); 621 mm_init_aio(mm); 622 mm_init_owner(mm, p); 623 mmu_notifier_mm_init(mm); 624 clear_tlb_flush_pending(mm); 625 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 626 mm->pmd_huge_pte = NULL; 627 #endif 628 629 if (current->mm) { 630 mm->flags = current->mm->flags & MMF_INIT_MASK; 631 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; 632 } else { 633 mm->flags = default_dump_filter; 634 mm->def_flags = 0; 635 } 636 637 if (mm_alloc_pgd(mm)) 638 goto fail_nopgd; 639 640 if (init_new_context(p, mm)) 641 goto fail_nocontext; 642 643 return mm; 644 645 fail_nocontext: 646 mm_free_pgd(mm); 647 fail_nopgd: 648 free_mm(mm); 649 return NULL; 650 } 651 652 static void check_mm(struct mm_struct *mm) 653 { 654 int i; 655 656 for (i = 0; i < NR_MM_COUNTERS; i++) { 657 long x = atomic_long_read(&mm->rss_stat.count[i]); 658 659 if (unlikely(x)) 660 printk(KERN_ALERT "BUG: Bad rss-counter state " 661 "mm:%p idx:%d val:%ld\n", mm, i, x); 662 } 663 664 if (atomic_long_read(&mm->nr_ptes)) 665 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n", 666 atomic_long_read(&mm->nr_ptes)); 667 if (mm_nr_pmds(mm)) 668 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n", 669 mm_nr_pmds(mm)); 670 671 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS 672 VM_BUG_ON_MM(mm->pmd_huge_pte, mm); 673 #endif 674 } 675 676 /* 677 * Allocate and initialize an mm_struct. 678 */ 679 struct mm_struct *mm_alloc(void) 680 { 681 struct mm_struct *mm; 682 683 mm = allocate_mm(); 684 if (!mm) 685 return NULL; 686 687 memset(mm, 0, sizeof(*mm)); 688 return mm_init(mm, current); 689 } 690 691 /* 692 * Called when the last reference to the mm 693 * is dropped: either by a lazy thread or by 694 * mmput. Free the page directory and the mm. 695 */ 696 void __mmdrop(struct mm_struct *mm) 697 { 698 BUG_ON(mm == &init_mm); 699 mm_free_pgd(mm); 700 destroy_context(mm); 701 mmu_notifier_mm_destroy(mm); 702 check_mm(mm); 703 free_mm(mm); 704 } 705 EXPORT_SYMBOL_GPL(__mmdrop); 706 707 static inline void __mmput(struct mm_struct *mm) 708 { 709 VM_BUG_ON(atomic_read(&mm->mm_users)); 710 711 uprobe_clear_state(mm); 712 exit_aio(mm); 713 ksm_exit(mm); 714 khugepaged_exit(mm); /* must run before exit_mmap */ 715 exit_mmap(mm); 716 set_mm_exe_file(mm, NULL); 717 if (!list_empty(&mm->mmlist)) { 718 spin_lock(&mmlist_lock); 719 list_del(&mm->mmlist); 720 spin_unlock(&mmlist_lock); 721 } 722 if (mm->binfmt) 723 module_put(mm->binfmt->module); 724 mmdrop(mm); 725 } 726 727 /* 728 * Decrement the use count and release all resources for an mm. 729 */ 730 void mmput(struct mm_struct *mm) 731 { 732 might_sleep(); 733 734 if (atomic_dec_and_test(&mm->mm_users)) 735 __mmput(mm); 736 } 737 EXPORT_SYMBOL_GPL(mmput); 738 739 #ifdef CONFIG_MMU 740 static void mmput_async_fn(struct work_struct *work) 741 { 742 struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work); 743 __mmput(mm); 744 } 745 746 void mmput_async(struct mm_struct *mm) 747 { 748 if (atomic_dec_and_test(&mm->mm_users)) { 749 INIT_WORK(&mm->async_put_work, mmput_async_fn); 750 schedule_work(&mm->async_put_work); 751 } 752 } 753 #endif 754 755 /** 756 * set_mm_exe_file - change a reference to the mm's executable file 757 * 758 * This changes mm's executable file (shown as symlink /proc/[pid]/exe). 759 * 760 * Main users are mmput() and sys_execve(). Callers prevent concurrent 761 * invocations: in mmput() nobody alive left, in execve task is single 762 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the 763 * mm->exe_file, but does so without using set_mm_exe_file() in order 764 * to do avoid the need for any locks. 765 */ 766 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) 767 { 768 struct file *old_exe_file; 769 770 /* 771 * It is safe to dereference the exe_file without RCU as 772 * this function is only called if nobody else can access 773 * this mm -- see comment above for justification. 774 */ 775 old_exe_file = rcu_dereference_raw(mm->exe_file); 776 777 if (new_exe_file) 778 get_file(new_exe_file); 779 rcu_assign_pointer(mm->exe_file, new_exe_file); 780 if (old_exe_file) 781 fput(old_exe_file); 782 } 783 784 /** 785 * get_mm_exe_file - acquire a reference to the mm's executable file 786 * 787 * Returns %NULL if mm has no associated executable file. 788 * User must release file via fput(). 789 */ 790 struct file *get_mm_exe_file(struct mm_struct *mm) 791 { 792 struct file *exe_file; 793 794 rcu_read_lock(); 795 exe_file = rcu_dereference(mm->exe_file); 796 if (exe_file && !get_file_rcu(exe_file)) 797 exe_file = NULL; 798 rcu_read_unlock(); 799 return exe_file; 800 } 801 EXPORT_SYMBOL(get_mm_exe_file); 802 803 /** 804 * get_task_mm - acquire a reference to the task's mm 805 * 806 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning 807 * this kernel workthread has transiently adopted a user mm with use_mm, 808 * to do its AIO) is not set and if so returns a reference to it, after 809 * bumping up the use count. User must release the mm via mmput() 810 * after use. Typically used by /proc and ptrace. 811 */ 812 struct mm_struct *get_task_mm(struct task_struct *task) 813 { 814 struct mm_struct *mm; 815 816 task_lock(task); 817 mm = task->mm; 818 if (mm) { 819 if (task->flags & PF_KTHREAD) 820 mm = NULL; 821 else 822 atomic_inc(&mm->mm_users); 823 } 824 task_unlock(task); 825 return mm; 826 } 827 EXPORT_SYMBOL_GPL(get_task_mm); 828 829 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) 830 { 831 struct mm_struct *mm; 832 int err; 833 834 err = mutex_lock_killable(&task->signal->cred_guard_mutex); 835 if (err) 836 return ERR_PTR(err); 837 838 mm = get_task_mm(task); 839 if (mm && mm != current->mm && 840 !ptrace_may_access(task, mode)) { 841 mmput(mm); 842 mm = ERR_PTR(-EACCES); 843 } 844 mutex_unlock(&task->signal->cred_guard_mutex); 845 846 return mm; 847 } 848 849 static void complete_vfork_done(struct task_struct *tsk) 850 { 851 struct completion *vfork; 852 853 task_lock(tsk); 854 vfork = tsk->vfork_done; 855 if (likely(vfork)) { 856 tsk->vfork_done = NULL; 857 complete(vfork); 858 } 859 task_unlock(tsk); 860 } 861 862 static int wait_for_vfork_done(struct task_struct *child, 863 struct completion *vfork) 864 { 865 int killed; 866 867 freezer_do_not_count(); 868 killed = wait_for_completion_killable(vfork); 869 freezer_count(); 870 871 if (killed) { 872 task_lock(child); 873 child->vfork_done = NULL; 874 task_unlock(child); 875 } 876 877 put_task_struct(child); 878 return killed; 879 } 880 881 /* Please note the differences between mmput and mm_release. 882 * mmput is called whenever we stop holding onto a mm_struct, 883 * error success whatever. 884 * 885 * mm_release is called after a mm_struct has been removed 886 * from the current process. 887 * 888 * This difference is important for error handling, when we 889 * only half set up a mm_struct for a new process and need to restore 890 * the old one. Because we mmput the new mm_struct before 891 * restoring the old one. . . 892 * Eric Biederman 10 January 1998 893 */ 894 void mm_release(struct task_struct *tsk, struct mm_struct *mm) 895 { 896 /* Get rid of any futexes when releasing the mm */ 897 #ifdef CONFIG_FUTEX 898 if (unlikely(tsk->robust_list)) { 899 exit_robust_list(tsk); 900 tsk->robust_list = NULL; 901 } 902 #ifdef CONFIG_COMPAT 903 if (unlikely(tsk->compat_robust_list)) { 904 compat_exit_robust_list(tsk); 905 tsk->compat_robust_list = NULL; 906 } 907 #endif 908 if (unlikely(!list_empty(&tsk->pi_state_list))) 909 exit_pi_state_list(tsk); 910 #endif 911 912 uprobe_free_utask(tsk); 913 914 /* Get rid of any cached register state */ 915 deactivate_mm(tsk, mm); 916 917 /* 918 * If we're exiting normally, clear a user-space tid field if 919 * requested. We leave this alone when dying by signal, to leave 920 * the value intact in a core dump, and to save the unnecessary 921 * trouble, say, a killed vfork parent shouldn't touch this mm. 922 * Userland only wants this done for a sys_exit. 923 */ 924 if (tsk->clear_child_tid) { 925 if (!(tsk->flags & PF_SIGNALED) && 926 atomic_read(&mm->mm_users) > 1) { 927 /* 928 * We don't check the error code - if userspace has 929 * not set up a proper pointer then tough luck. 930 */ 931 put_user(0, tsk->clear_child_tid); 932 sys_futex(tsk->clear_child_tid, FUTEX_WAKE, 933 1, NULL, NULL, 0); 934 } 935 tsk->clear_child_tid = NULL; 936 } 937 938 /* 939 * All done, finally we can wake up parent and return this mm to him. 940 * Also kthread_stop() uses this completion for synchronization. 941 */ 942 if (tsk->vfork_done) 943 complete_vfork_done(tsk); 944 } 945 946 /* 947 * Allocate a new mm structure and copy contents from the 948 * mm structure of the passed in task structure. 949 */ 950 static struct mm_struct *dup_mm(struct task_struct *tsk) 951 { 952 struct mm_struct *mm, *oldmm = current->mm; 953 int err; 954 955 mm = allocate_mm(); 956 if (!mm) 957 goto fail_nomem; 958 959 memcpy(mm, oldmm, sizeof(*mm)); 960 961 if (!mm_init(mm, tsk)) 962 goto fail_nomem; 963 964 err = dup_mmap(mm, oldmm); 965 if (err) 966 goto free_pt; 967 968 mm->hiwater_rss = get_mm_rss(mm); 969 mm->hiwater_vm = mm->total_vm; 970 971 if (mm->binfmt && !try_module_get(mm->binfmt->module)) 972 goto free_pt; 973 974 return mm; 975 976 free_pt: 977 /* don't put binfmt in mmput, we haven't got module yet */ 978 mm->binfmt = NULL; 979 mmput(mm); 980 981 fail_nomem: 982 return NULL; 983 } 984 985 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) 986 { 987 struct mm_struct *mm, *oldmm; 988 int retval; 989 990 tsk->min_flt = tsk->maj_flt = 0; 991 tsk->nvcsw = tsk->nivcsw = 0; 992 #ifdef CONFIG_DETECT_HUNG_TASK 993 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; 994 #endif 995 996 tsk->mm = NULL; 997 tsk->active_mm = NULL; 998 999 /* 1000 * Are we cloning a kernel thread? 1001 * 1002 * We need to steal a active VM for that.. 1003 */ 1004 oldmm = current->mm; 1005 if (!oldmm) 1006 return 0; 1007 1008 /* initialize the new vmacache entries */ 1009 vmacache_flush(tsk); 1010 1011 if (clone_flags & CLONE_VM) { 1012 atomic_inc(&oldmm->mm_users); 1013 mm = oldmm; 1014 goto good_mm; 1015 } 1016 1017 retval = -ENOMEM; 1018 mm = dup_mm(tsk); 1019 if (!mm) 1020 goto fail_nomem; 1021 1022 good_mm: 1023 tsk->mm = mm; 1024 tsk->active_mm = mm; 1025 return 0; 1026 1027 fail_nomem: 1028 return retval; 1029 } 1030 1031 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) 1032 { 1033 struct fs_struct *fs = current->fs; 1034 if (clone_flags & CLONE_FS) { 1035 /* tsk->fs is already what we want */ 1036 spin_lock(&fs->lock); 1037 if (fs->in_exec) { 1038 spin_unlock(&fs->lock); 1039 return -EAGAIN; 1040 } 1041 fs->users++; 1042 spin_unlock(&fs->lock); 1043 return 0; 1044 } 1045 tsk->fs = copy_fs_struct(fs); 1046 if (!tsk->fs) 1047 return -ENOMEM; 1048 return 0; 1049 } 1050 1051 static int copy_files(unsigned long clone_flags, struct task_struct *tsk) 1052 { 1053 struct files_struct *oldf, *newf; 1054 int error = 0; 1055 1056 /* 1057 * A background process may not have any files ... 1058 */ 1059 oldf = current->files; 1060 if (!oldf) 1061 goto out; 1062 1063 if (clone_flags & CLONE_FILES) { 1064 atomic_inc(&oldf->count); 1065 goto out; 1066 } 1067 1068 newf = dup_fd(oldf, &error); 1069 if (!newf) 1070 goto out; 1071 1072 tsk->files = newf; 1073 error = 0; 1074 out: 1075 return error; 1076 } 1077 1078 static int copy_io(unsigned long clone_flags, struct task_struct *tsk) 1079 { 1080 #ifdef CONFIG_BLOCK 1081 struct io_context *ioc = current->io_context; 1082 struct io_context *new_ioc; 1083 1084 if (!ioc) 1085 return 0; 1086 /* 1087 * Share io context with parent, if CLONE_IO is set 1088 */ 1089 if (clone_flags & CLONE_IO) { 1090 ioc_task_link(ioc); 1091 tsk->io_context = ioc; 1092 } else if (ioprio_valid(ioc->ioprio)) { 1093 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); 1094 if (unlikely(!new_ioc)) 1095 return -ENOMEM; 1096 1097 new_ioc->ioprio = ioc->ioprio; 1098 put_io_context(new_ioc); 1099 } 1100 #endif 1101 return 0; 1102 } 1103 1104 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) 1105 { 1106 struct sighand_struct *sig; 1107 1108 if (clone_flags & CLONE_SIGHAND) { 1109 atomic_inc(¤t->sighand->count); 1110 return 0; 1111 } 1112 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); 1113 rcu_assign_pointer(tsk->sighand, sig); 1114 if (!sig) 1115 return -ENOMEM; 1116 1117 atomic_set(&sig->count, 1); 1118 memcpy(sig->action, current->sighand->action, sizeof(sig->action)); 1119 return 0; 1120 } 1121 1122 void __cleanup_sighand(struct sighand_struct *sighand) 1123 { 1124 if (atomic_dec_and_test(&sighand->count)) { 1125 signalfd_cleanup(sighand); 1126 /* 1127 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it 1128 * without an RCU grace period, see __lock_task_sighand(). 1129 */ 1130 kmem_cache_free(sighand_cachep, sighand); 1131 } 1132 } 1133 1134 /* 1135 * Initialize POSIX timer handling for a thread group. 1136 */ 1137 static void posix_cpu_timers_init_group(struct signal_struct *sig) 1138 { 1139 unsigned long cpu_limit; 1140 1141 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); 1142 if (cpu_limit != RLIM_INFINITY) { 1143 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); 1144 sig->cputimer.running = true; 1145 } 1146 1147 /* The timer lists. */ 1148 INIT_LIST_HEAD(&sig->cpu_timers[0]); 1149 INIT_LIST_HEAD(&sig->cpu_timers[1]); 1150 INIT_LIST_HEAD(&sig->cpu_timers[2]); 1151 } 1152 1153 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) 1154 { 1155 struct signal_struct *sig; 1156 1157 if (clone_flags & CLONE_THREAD) 1158 return 0; 1159 1160 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); 1161 tsk->signal = sig; 1162 if (!sig) 1163 return -ENOMEM; 1164 1165 sig->nr_threads = 1; 1166 atomic_set(&sig->live, 1); 1167 atomic_set(&sig->sigcnt, 1); 1168 1169 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ 1170 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); 1171 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head); 1172 1173 init_waitqueue_head(&sig->wait_chldexit); 1174 sig->curr_target = tsk; 1175 init_sigpending(&sig->shared_pending); 1176 INIT_LIST_HEAD(&sig->posix_timers); 1177 seqlock_init(&sig->stats_lock); 1178 prev_cputime_init(&sig->prev_cputime); 1179 1180 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 1181 sig->real_timer.function = it_real_fn; 1182 1183 task_lock(current->group_leader); 1184 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); 1185 task_unlock(current->group_leader); 1186 1187 posix_cpu_timers_init_group(sig); 1188 1189 tty_audit_fork(sig); 1190 sched_autogroup_fork(sig); 1191 1192 sig->oom_score_adj = current->signal->oom_score_adj; 1193 sig->oom_score_adj_min = current->signal->oom_score_adj_min; 1194 1195 sig->has_child_subreaper = current->signal->has_child_subreaper || 1196 current->signal->is_child_subreaper; 1197 1198 mutex_init(&sig->cred_guard_mutex); 1199 1200 return 0; 1201 } 1202 1203 static void copy_seccomp(struct task_struct *p) 1204 { 1205 #ifdef CONFIG_SECCOMP 1206 /* 1207 * Must be called with sighand->lock held, which is common to 1208 * all threads in the group. Holding cred_guard_mutex is not 1209 * needed because this new task is not yet running and cannot 1210 * be racing exec. 1211 */ 1212 assert_spin_locked(¤t->sighand->siglock); 1213 1214 /* Ref-count the new filter user, and assign it. */ 1215 get_seccomp_filter(current); 1216 p->seccomp = current->seccomp; 1217 1218 /* 1219 * Explicitly enable no_new_privs here in case it got set 1220 * between the task_struct being duplicated and holding the 1221 * sighand lock. The seccomp state and nnp must be in sync. 1222 */ 1223 if (task_no_new_privs(current)) 1224 task_set_no_new_privs(p); 1225 1226 /* 1227 * If the parent gained a seccomp mode after copying thread 1228 * flags and between before we held the sighand lock, we have 1229 * to manually enable the seccomp thread flag here. 1230 */ 1231 if (p->seccomp.mode != SECCOMP_MODE_DISABLED) 1232 set_tsk_thread_flag(p, TIF_SECCOMP); 1233 #endif 1234 } 1235 1236 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) 1237 { 1238 current->clear_child_tid = tidptr; 1239 1240 return task_pid_vnr(current); 1241 } 1242 1243 static void rt_mutex_init_task(struct task_struct *p) 1244 { 1245 raw_spin_lock_init(&p->pi_lock); 1246 #ifdef CONFIG_RT_MUTEXES 1247 p->pi_waiters = RB_ROOT; 1248 p->pi_waiters_leftmost = NULL; 1249 p->pi_blocked_on = NULL; 1250 #endif 1251 } 1252 1253 /* 1254 * Initialize POSIX timer handling for a single task. 1255 */ 1256 static void posix_cpu_timers_init(struct task_struct *tsk) 1257 { 1258 tsk->cputime_expires.prof_exp = 0; 1259 tsk->cputime_expires.virt_exp = 0; 1260 tsk->cputime_expires.sched_exp = 0; 1261 INIT_LIST_HEAD(&tsk->cpu_timers[0]); 1262 INIT_LIST_HEAD(&tsk->cpu_timers[1]); 1263 INIT_LIST_HEAD(&tsk->cpu_timers[2]); 1264 } 1265 1266 static inline void 1267 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) 1268 { 1269 task->pids[type].pid = pid; 1270 } 1271 1272 /* 1273 * This creates a new process as a copy of the old one, 1274 * but does not actually start it yet. 1275 * 1276 * It copies the registers, and all the appropriate 1277 * parts of the process environment (as per the clone 1278 * flags). The actual kick-off is left to the caller. 1279 */ 1280 static struct task_struct *copy_process(unsigned long clone_flags, 1281 unsigned long stack_start, 1282 unsigned long stack_size, 1283 int __user *child_tidptr, 1284 struct pid *pid, 1285 int trace, 1286 unsigned long tls, 1287 int node) 1288 { 1289 int retval; 1290 struct task_struct *p; 1291 1292 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) 1293 return ERR_PTR(-EINVAL); 1294 1295 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) 1296 return ERR_PTR(-EINVAL); 1297 1298 /* 1299 * Thread groups must share signals as well, and detached threads 1300 * can only be started up within the thread group. 1301 */ 1302 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) 1303 return ERR_PTR(-EINVAL); 1304 1305 /* 1306 * Shared signal handlers imply shared VM. By way of the above, 1307 * thread groups also imply shared VM. Blocking this case allows 1308 * for various simplifications in other code. 1309 */ 1310 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) 1311 return ERR_PTR(-EINVAL); 1312 1313 /* 1314 * Siblings of global init remain as zombies on exit since they are 1315 * not reaped by their parent (swapper). To solve this and to avoid 1316 * multi-rooted process trees, prevent global and container-inits 1317 * from creating siblings. 1318 */ 1319 if ((clone_flags & CLONE_PARENT) && 1320 current->signal->flags & SIGNAL_UNKILLABLE) 1321 return ERR_PTR(-EINVAL); 1322 1323 /* 1324 * If the new process will be in a different pid or user namespace 1325 * do not allow it to share a thread group with the forking task. 1326 */ 1327 if (clone_flags & CLONE_THREAD) { 1328 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || 1329 (task_active_pid_ns(current) != 1330 current->nsproxy->pid_ns_for_children)) 1331 return ERR_PTR(-EINVAL); 1332 } 1333 1334 retval = security_task_create(clone_flags); 1335 if (retval) 1336 goto fork_out; 1337 1338 retval = -ENOMEM; 1339 p = dup_task_struct(current, node); 1340 if (!p) 1341 goto fork_out; 1342 1343 ftrace_graph_init_task(p); 1344 1345 rt_mutex_init_task(p); 1346 1347 #ifdef CONFIG_PROVE_LOCKING 1348 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); 1349 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); 1350 #endif 1351 retval = -EAGAIN; 1352 if (atomic_read(&p->real_cred->user->processes) >= 1353 task_rlimit(p, RLIMIT_NPROC)) { 1354 if (p->real_cred->user != INIT_USER && 1355 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) 1356 goto bad_fork_free; 1357 } 1358 current->flags &= ~PF_NPROC_EXCEEDED; 1359 1360 retval = copy_creds(p, clone_flags); 1361 if (retval < 0) 1362 goto bad_fork_free; 1363 1364 /* 1365 * If multiple threads are within copy_process(), then this check 1366 * triggers too late. This doesn't hurt, the check is only there 1367 * to stop root fork bombs. 1368 */ 1369 retval = -EAGAIN; 1370 if (nr_threads >= max_threads) 1371 goto bad_fork_cleanup_count; 1372 1373 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ 1374 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); 1375 p->flags |= PF_FORKNOEXEC; 1376 INIT_LIST_HEAD(&p->children); 1377 INIT_LIST_HEAD(&p->sibling); 1378 rcu_copy_process(p); 1379 p->vfork_done = NULL; 1380 spin_lock_init(&p->alloc_lock); 1381 1382 init_sigpending(&p->pending); 1383 1384 p->utime = p->stime = p->gtime = 0; 1385 p->utimescaled = p->stimescaled = 0; 1386 prev_cputime_init(&p->prev_cputime); 1387 1388 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN 1389 seqcount_init(&p->vtime_seqcount); 1390 p->vtime_snap = 0; 1391 p->vtime_snap_whence = VTIME_INACTIVE; 1392 #endif 1393 1394 #if defined(SPLIT_RSS_COUNTING) 1395 memset(&p->rss_stat, 0, sizeof(p->rss_stat)); 1396 #endif 1397 1398 p->default_timer_slack_ns = current->timer_slack_ns; 1399 1400 task_io_accounting_init(&p->ioac); 1401 acct_clear_integrals(p); 1402 1403 posix_cpu_timers_init(p); 1404 1405 p->start_time = ktime_get_ns(); 1406 p->real_start_time = ktime_get_boot_ns(); 1407 p->io_context = NULL; 1408 p->audit_context = NULL; 1409 threadgroup_change_begin(current); 1410 cgroup_fork(p); 1411 #ifdef CONFIG_NUMA 1412 p->mempolicy = mpol_dup(p->mempolicy); 1413 if (IS_ERR(p->mempolicy)) { 1414 retval = PTR_ERR(p->mempolicy); 1415 p->mempolicy = NULL; 1416 goto bad_fork_cleanup_threadgroup_lock; 1417 } 1418 #endif 1419 #ifdef CONFIG_CPUSETS 1420 p->cpuset_mem_spread_rotor = NUMA_NO_NODE; 1421 p->cpuset_slab_spread_rotor = NUMA_NO_NODE; 1422 seqcount_init(&p->mems_allowed_seq); 1423 #endif 1424 #ifdef CONFIG_TRACE_IRQFLAGS 1425 p->irq_events = 0; 1426 p->hardirqs_enabled = 0; 1427 p->hardirq_enable_ip = 0; 1428 p->hardirq_enable_event = 0; 1429 p->hardirq_disable_ip = _THIS_IP_; 1430 p->hardirq_disable_event = 0; 1431 p->softirqs_enabled = 1; 1432 p->softirq_enable_ip = _THIS_IP_; 1433 p->softirq_enable_event = 0; 1434 p->softirq_disable_ip = 0; 1435 p->softirq_disable_event = 0; 1436 p->hardirq_context = 0; 1437 p->softirq_context = 0; 1438 #endif 1439 1440 p->pagefault_disabled = 0; 1441 1442 #ifdef CONFIG_LOCKDEP 1443 p->lockdep_depth = 0; /* no locks held yet */ 1444 p->curr_chain_key = 0; 1445 p->lockdep_recursion = 0; 1446 #endif 1447 1448 #ifdef CONFIG_DEBUG_MUTEXES 1449 p->blocked_on = NULL; /* not blocked yet */ 1450 #endif 1451 #ifdef CONFIG_BCACHE 1452 p->sequential_io = 0; 1453 p->sequential_io_avg = 0; 1454 #endif 1455 1456 /* Perform scheduler related setup. Assign this task to a CPU. */ 1457 retval = sched_fork(clone_flags, p); 1458 if (retval) 1459 goto bad_fork_cleanup_policy; 1460 1461 retval = perf_event_init_task(p); 1462 if (retval) 1463 goto bad_fork_cleanup_policy; 1464 retval = audit_alloc(p); 1465 if (retval) 1466 goto bad_fork_cleanup_perf; 1467 /* copy all the process information */ 1468 shm_init_task(p); 1469 retval = copy_semundo(clone_flags, p); 1470 if (retval) 1471 goto bad_fork_cleanup_audit; 1472 retval = copy_files(clone_flags, p); 1473 if (retval) 1474 goto bad_fork_cleanup_semundo; 1475 retval = copy_fs(clone_flags, p); 1476 if (retval) 1477 goto bad_fork_cleanup_files; 1478 retval = copy_sighand(clone_flags, p); 1479 if (retval) 1480 goto bad_fork_cleanup_fs; 1481 retval = copy_signal(clone_flags, p); 1482 if (retval) 1483 goto bad_fork_cleanup_sighand; 1484 retval = copy_mm(clone_flags, p); 1485 if (retval) 1486 goto bad_fork_cleanup_signal; 1487 retval = copy_namespaces(clone_flags, p); 1488 if (retval) 1489 goto bad_fork_cleanup_mm; 1490 retval = copy_io(clone_flags, p); 1491 if (retval) 1492 goto bad_fork_cleanup_namespaces; 1493 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls); 1494 if (retval) 1495 goto bad_fork_cleanup_io; 1496 1497 if (pid != &init_struct_pid) { 1498 pid = alloc_pid(p->nsproxy->pid_ns_for_children); 1499 if (IS_ERR(pid)) { 1500 retval = PTR_ERR(pid); 1501 goto bad_fork_cleanup_thread; 1502 } 1503 } 1504 1505 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; 1506 /* 1507 * Clear TID on mm_release()? 1508 */ 1509 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; 1510 #ifdef CONFIG_BLOCK 1511 p->plug = NULL; 1512 #endif 1513 #ifdef CONFIG_FUTEX 1514 p->robust_list = NULL; 1515 #ifdef CONFIG_COMPAT 1516 p->compat_robust_list = NULL; 1517 #endif 1518 INIT_LIST_HEAD(&p->pi_state_list); 1519 p->pi_state_cache = NULL; 1520 #endif 1521 /* 1522 * sigaltstack should be cleared when sharing the same VM 1523 */ 1524 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) 1525 sas_ss_reset(p); 1526 1527 /* 1528 * Syscall tracing and stepping should be turned off in the 1529 * child regardless of CLONE_PTRACE. 1530 */ 1531 user_disable_single_step(p); 1532 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); 1533 #ifdef TIF_SYSCALL_EMU 1534 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); 1535 #endif 1536 clear_all_latency_tracing(p); 1537 1538 /* ok, now we should be set up.. */ 1539 p->pid = pid_nr(pid); 1540 if (clone_flags & CLONE_THREAD) { 1541 p->exit_signal = -1; 1542 p->group_leader = current->group_leader; 1543 p->tgid = current->tgid; 1544 } else { 1545 if (clone_flags & CLONE_PARENT) 1546 p->exit_signal = current->group_leader->exit_signal; 1547 else 1548 p->exit_signal = (clone_flags & CSIGNAL); 1549 p->group_leader = p; 1550 p->tgid = p->pid; 1551 } 1552 1553 p->nr_dirtied = 0; 1554 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); 1555 p->dirty_paused_when = 0; 1556 1557 p->pdeath_signal = 0; 1558 INIT_LIST_HEAD(&p->thread_group); 1559 p->task_works = NULL; 1560 1561 /* 1562 * Ensure that the cgroup subsystem policies allow the new process to be 1563 * forked. It should be noted the the new process's css_set can be changed 1564 * between here and cgroup_post_fork() if an organisation operation is in 1565 * progress. 1566 */ 1567 retval = cgroup_can_fork(p); 1568 if (retval) 1569 goto bad_fork_free_pid; 1570 1571 /* 1572 * Make it visible to the rest of the system, but dont wake it up yet. 1573 * Need tasklist lock for parent etc handling! 1574 */ 1575 write_lock_irq(&tasklist_lock); 1576 1577 /* CLONE_PARENT re-uses the old parent */ 1578 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { 1579 p->real_parent = current->real_parent; 1580 p->parent_exec_id = current->parent_exec_id; 1581 } else { 1582 p->real_parent = current; 1583 p->parent_exec_id = current->self_exec_id; 1584 } 1585 1586 spin_lock(¤t->sighand->siglock); 1587 1588 /* 1589 * Copy seccomp details explicitly here, in case they were changed 1590 * before holding sighand lock. 1591 */ 1592 copy_seccomp(p); 1593 1594 /* 1595 * Process group and session signals need to be delivered to just the 1596 * parent before the fork or both the parent and the child after the 1597 * fork. Restart if a signal comes in before we add the new process to 1598 * it's process group. 1599 * A fatal signal pending means that current will exit, so the new 1600 * thread can't slip out of an OOM kill (or normal SIGKILL). 1601 */ 1602 recalc_sigpending(); 1603 if (signal_pending(current)) { 1604 spin_unlock(¤t->sighand->siglock); 1605 write_unlock_irq(&tasklist_lock); 1606 retval = -ERESTARTNOINTR; 1607 goto bad_fork_cancel_cgroup; 1608 } 1609 1610 if (likely(p->pid)) { 1611 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); 1612 1613 init_task_pid(p, PIDTYPE_PID, pid); 1614 if (thread_group_leader(p)) { 1615 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); 1616 init_task_pid(p, PIDTYPE_SID, task_session(current)); 1617 1618 if (is_child_reaper(pid)) { 1619 ns_of_pid(pid)->child_reaper = p; 1620 p->signal->flags |= SIGNAL_UNKILLABLE; 1621 } 1622 1623 p->signal->leader_pid = pid; 1624 p->signal->tty = tty_kref_get(current->signal->tty); 1625 list_add_tail(&p->sibling, &p->real_parent->children); 1626 list_add_tail_rcu(&p->tasks, &init_task.tasks); 1627 attach_pid(p, PIDTYPE_PGID); 1628 attach_pid(p, PIDTYPE_SID); 1629 __this_cpu_inc(process_counts); 1630 } else { 1631 current->signal->nr_threads++; 1632 atomic_inc(¤t->signal->live); 1633 atomic_inc(¤t->signal->sigcnt); 1634 list_add_tail_rcu(&p->thread_group, 1635 &p->group_leader->thread_group); 1636 list_add_tail_rcu(&p->thread_node, 1637 &p->signal->thread_head); 1638 } 1639 attach_pid(p, PIDTYPE_PID); 1640 nr_threads++; 1641 } 1642 1643 total_forks++; 1644 spin_unlock(¤t->sighand->siglock); 1645 syscall_tracepoint_update(p); 1646 write_unlock_irq(&tasklist_lock); 1647 1648 proc_fork_connector(p); 1649 cgroup_post_fork(p); 1650 threadgroup_change_end(current); 1651 perf_event_fork(p); 1652 1653 trace_task_newtask(p, clone_flags); 1654 uprobe_copy_process(p, clone_flags); 1655 1656 return p; 1657 1658 bad_fork_cancel_cgroup: 1659 cgroup_cancel_fork(p); 1660 bad_fork_free_pid: 1661 if (pid != &init_struct_pid) 1662 free_pid(pid); 1663 bad_fork_cleanup_thread: 1664 exit_thread(p); 1665 bad_fork_cleanup_io: 1666 if (p->io_context) 1667 exit_io_context(p); 1668 bad_fork_cleanup_namespaces: 1669 exit_task_namespaces(p); 1670 bad_fork_cleanup_mm: 1671 if (p->mm) 1672 mmput(p->mm); 1673 bad_fork_cleanup_signal: 1674 if (!(clone_flags & CLONE_THREAD)) 1675 free_signal_struct(p->signal); 1676 bad_fork_cleanup_sighand: 1677 __cleanup_sighand(p->sighand); 1678 bad_fork_cleanup_fs: 1679 exit_fs(p); /* blocking */ 1680 bad_fork_cleanup_files: 1681 exit_files(p); /* blocking */ 1682 bad_fork_cleanup_semundo: 1683 exit_sem(p); 1684 bad_fork_cleanup_audit: 1685 audit_free(p); 1686 bad_fork_cleanup_perf: 1687 perf_event_free_task(p); 1688 bad_fork_cleanup_policy: 1689 #ifdef CONFIG_NUMA 1690 mpol_put(p->mempolicy); 1691 bad_fork_cleanup_threadgroup_lock: 1692 #endif 1693 threadgroup_change_end(current); 1694 delayacct_tsk_free(p); 1695 bad_fork_cleanup_count: 1696 atomic_dec(&p->cred->user->processes); 1697 exit_creds(p); 1698 bad_fork_free: 1699 free_task(p); 1700 fork_out: 1701 return ERR_PTR(retval); 1702 } 1703 1704 static inline void init_idle_pids(struct pid_link *links) 1705 { 1706 enum pid_type type; 1707 1708 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { 1709 INIT_HLIST_NODE(&links[type].node); /* not really needed */ 1710 links[type].pid = &init_struct_pid; 1711 } 1712 } 1713 1714 struct task_struct *fork_idle(int cpu) 1715 { 1716 struct task_struct *task; 1717 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, 1718 cpu_to_node(cpu)); 1719 if (!IS_ERR(task)) { 1720 init_idle_pids(task->pids); 1721 init_idle(task, cpu); 1722 } 1723 1724 return task; 1725 } 1726 1727 /* 1728 * Ok, this is the main fork-routine. 1729 * 1730 * It copies the process, and if successful kick-starts 1731 * it and waits for it to finish using the VM if required. 1732 */ 1733 long _do_fork(unsigned long clone_flags, 1734 unsigned long stack_start, 1735 unsigned long stack_size, 1736 int __user *parent_tidptr, 1737 int __user *child_tidptr, 1738 unsigned long tls) 1739 { 1740 struct task_struct *p; 1741 int trace = 0; 1742 long nr; 1743 1744 /* 1745 * Determine whether and which event to report to ptracer. When 1746 * called from kernel_thread or CLONE_UNTRACED is explicitly 1747 * requested, no event is reported; otherwise, report if the event 1748 * for the type of forking is enabled. 1749 */ 1750 if (!(clone_flags & CLONE_UNTRACED)) { 1751 if (clone_flags & CLONE_VFORK) 1752 trace = PTRACE_EVENT_VFORK; 1753 else if ((clone_flags & CSIGNAL) != SIGCHLD) 1754 trace = PTRACE_EVENT_CLONE; 1755 else 1756 trace = PTRACE_EVENT_FORK; 1757 1758 if (likely(!ptrace_event_enabled(current, trace))) 1759 trace = 0; 1760 } 1761 1762 p = copy_process(clone_flags, stack_start, stack_size, 1763 child_tidptr, NULL, trace, tls, NUMA_NO_NODE); 1764 /* 1765 * Do this prior waking up the new thread - the thread pointer 1766 * might get invalid after that point, if the thread exits quickly. 1767 */ 1768 if (!IS_ERR(p)) { 1769 struct completion vfork; 1770 struct pid *pid; 1771 1772 trace_sched_process_fork(current, p); 1773 1774 pid = get_task_pid(p, PIDTYPE_PID); 1775 nr = pid_vnr(pid); 1776 1777 if (clone_flags & CLONE_PARENT_SETTID) 1778 put_user(nr, parent_tidptr); 1779 1780 if (clone_flags & CLONE_VFORK) { 1781 p->vfork_done = &vfork; 1782 init_completion(&vfork); 1783 get_task_struct(p); 1784 } 1785 1786 wake_up_new_task(p); 1787 1788 /* forking complete and child started to run, tell ptracer */ 1789 if (unlikely(trace)) 1790 ptrace_event_pid(trace, pid); 1791 1792 if (clone_flags & CLONE_VFORK) { 1793 if (!wait_for_vfork_done(p, &vfork)) 1794 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid); 1795 } 1796 1797 put_pid(pid); 1798 } else { 1799 nr = PTR_ERR(p); 1800 } 1801 return nr; 1802 } 1803 1804 #ifndef CONFIG_HAVE_COPY_THREAD_TLS 1805 /* For compatibility with architectures that call do_fork directly rather than 1806 * using the syscall entry points below. */ 1807 long do_fork(unsigned long clone_flags, 1808 unsigned long stack_start, 1809 unsigned long stack_size, 1810 int __user *parent_tidptr, 1811 int __user *child_tidptr) 1812 { 1813 return _do_fork(clone_flags, stack_start, stack_size, 1814 parent_tidptr, child_tidptr, 0); 1815 } 1816 #endif 1817 1818 /* 1819 * Create a kernel thread. 1820 */ 1821 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) 1822 { 1823 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, 1824 (unsigned long)arg, NULL, NULL, 0); 1825 } 1826 1827 #ifdef __ARCH_WANT_SYS_FORK 1828 SYSCALL_DEFINE0(fork) 1829 { 1830 #ifdef CONFIG_MMU 1831 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0); 1832 #else 1833 /* can not support in nommu mode */ 1834 return -EINVAL; 1835 #endif 1836 } 1837 #endif 1838 1839 #ifdef __ARCH_WANT_SYS_VFORK 1840 SYSCALL_DEFINE0(vfork) 1841 { 1842 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, 1843 0, NULL, NULL, 0); 1844 } 1845 #endif 1846 1847 #ifdef __ARCH_WANT_SYS_CLONE 1848 #ifdef CONFIG_CLONE_BACKWARDS 1849 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 1850 int __user *, parent_tidptr, 1851 unsigned long, tls, 1852 int __user *, child_tidptr) 1853 #elif defined(CONFIG_CLONE_BACKWARDS2) 1854 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, 1855 int __user *, parent_tidptr, 1856 int __user *, child_tidptr, 1857 unsigned long, tls) 1858 #elif defined(CONFIG_CLONE_BACKWARDS3) 1859 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, 1860 int, stack_size, 1861 int __user *, parent_tidptr, 1862 int __user *, child_tidptr, 1863 unsigned long, tls) 1864 #else 1865 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, 1866 int __user *, parent_tidptr, 1867 int __user *, child_tidptr, 1868 unsigned long, tls) 1869 #endif 1870 { 1871 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls); 1872 } 1873 #endif 1874 1875 #ifndef ARCH_MIN_MMSTRUCT_ALIGN 1876 #define ARCH_MIN_MMSTRUCT_ALIGN 0 1877 #endif 1878 1879 static void sighand_ctor(void *data) 1880 { 1881 struct sighand_struct *sighand = data; 1882 1883 spin_lock_init(&sighand->siglock); 1884 init_waitqueue_head(&sighand->signalfd_wqh); 1885 } 1886 1887 void __init proc_caches_init(void) 1888 { 1889 sighand_cachep = kmem_cache_create("sighand_cache", 1890 sizeof(struct sighand_struct), 0, 1891 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| 1892 SLAB_NOTRACK|SLAB_ACCOUNT, sighand_ctor); 1893 signal_cachep = kmem_cache_create("signal_cache", 1894 sizeof(struct signal_struct), 0, 1895 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK|SLAB_ACCOUNT, 1896 NULL); 1897 files_cachep = kmem_cache_create("files_cache", 1898 sizeof(struct files_struct), 0, 1899 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK|SLAB_ACCOUNT, 1900 NULL); 1901 fs_cachep = kmem_cache_create("fs_cache", 1902 sizeof(struct fs_struct), 0, 1903 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK|SLAB_ACCOUNT, 1904 NULL); 1905 /* 1906 * FIXME! The "sizeof(struct mm_struct)" currently includes the 1907 * whole struct cpumask for the OFFSTACK case. We could change 1908 * this to *only* allocate as much of it as required by the 1909 * maximum number of CPU's we can ever have. The cpumask_allocation 1910 * is at the end of the structure, exactly for that reason. 1911 */ 1912 mm_cachep = kmem_cache_create("mm_struct", 1913 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, 1914 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK|SLAB_ACCOUNT, 1915 NULL); 1916 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); 1917 mmap_init(); 1918 nsproxy_cache_init(); 1919 } 1920 1921 /* 1922 * Check constraints on flags passed to the unshare system call. 1923 */ 1924 static int check_unshare_flags(unsigned long unshare_flags) 1925 { 1926 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| 1927 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| 1928 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| 1929 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP)) 1930 return -EINVAL; 1931 /* 1932 * Not implemented, but pretend it works if there is nothing 1933 * to unshare. Note that unsharing the address space or the 1934 * signal handlers also need to unshare the signal queues (aka 1935 * CLONE_THREAD). 1936 */ 1937 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { 1938 if (!thread_group_empty(current)) 1939 return -EINVAL; 1940 } 1941 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) { 1942 if (atomic_read(¤t->sighand->count) > 1) 1943 return -EINVAL; 1944 } 1945 if (unshare_flags & CLONE_VM) { 1946 if (!current_is_single_threaded()) 1947 return -EINVAL; 1948 } 1949 1950 return 0; 1951 } 1952 1953 /* 1954 * Unshare the filesystem structure if it is being shared 1955 */ 1956 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) 1957 { 1958 struct fs_struct *fs = current->fs; 1959 1960 if (!(unshare_flags & CLONE_FS) || !fs) 1961 return 0; 1962 1963 /* don't need lock here; in the worst case we'll do useless copy */ 1964 if (fs->users == 1) 1965 return 0; 1966 1967 *new_fsp = copy_fs_struct(fs); 1968 if (!*new_fsp) 1969 return -ENOMEM; 1970 1971 return 0; 1972 } 1973 1974 /* 1975 * Unshare file descriptor table if it is being shared 1976 */ 1977 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) 1978 { 1979 struct files_struct *fd = current->files; 1980 int error = 0; 1981 1982 if ((unshare_flags & CLONE_FILES) && 1983 (fd && atomic_read(&fd->count) > 1)) { 1984 *new_fdp = dup_fd(fd, &error); 1985 if (!*new_fdp) 1986 return error; 1987 } 1988 1989 return 0; 1990 } 1991 1992 /* 1993 * unshare allows a process to 'unshare' part of the process 1994 * context which was originally shared using clone. copy_* 1995 * functions used by do_fork() cannot be used here directly 1996 * because they modify an inactive task_struct that is being 1997 * constructed. Here we are modifying the current, active, 1998 * task_struct. 1999 */ 2000 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) 2001 { 2002 struct fs_struct *fs, *new_fs = NULL; 2003 struct files_struct *fd, *new_fd = NULL; 2004 struct cred *new_cred = NULL; 2005 struct nsproxy *new_nsproxy = NULL; 2006 int do_sysvsem = 0; 2007 int err; 2008 2009 /* 2010 * If unsharing a user namespace must also unshare the thread group 2011 * and unshare the filesystem root and working directories. 2012 */ 2013 if (unshare_flags & CLONE_NEWUSER) 2014 unshare_flags |= CLONE_THREAD | CLONE_FS; 2015 /* 2016 * If unsharing vm, must also unshare signal handlers. 2017 */ 2018 if (unshare_flags & CLONE_VM) 2019 unshare_flags |= CLONE_SIGHAND; 2020 /* 2021 * If unsharing a signal handlers, must also unshare the signal queues. 2022 */ 2023 if (unshare_flags & CLONE_SIGHAND) 2024 unshare_flags |= CLONE_THREAD; 2025 /* 2026 * If unsharing namespace, must also unshare filesystem information. 2027 */ 2028 if (unshare_flags & CLONE_NEWNS) 2029 unshare_flags |= CLONE_FS; 2030 2031 err = check_unshare_flags(unshare_flags); 2032 if (err) 2033 goto bad_unshare_out; 2034 /* 2035 * CLONE_NEWIPC must also detach from the undolist: after switching 2036 * to a new ipc namespace, the semaphore arrays from the old 2037 * namespace are unreachable. 2038 */ 2039 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) 2040 do_sysvsem = 1; 2041 err = unshare_fs(unshare_flags, &new_fs); 2042 if (err) 2043 goto bad_unshare_out; 2044 err = unshare_fd(unshare_flags, &new_fd); 2045 if (err) 2046 goto bad_unshare_cleanup_fs; 2047 err = unshare_userns(unshare_flags, &new_cred); 2048 if (err) 2049 goto bad_unshare_cleanup_fd; 2050 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, 2051 new_cred, new_fs); 2052 if (err) 2053 goto bad_unshare_cleanup_cred; 2054 2055 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { 2056 if (do_sysvsem) { 2057 /* 2058 * CLONE_SYSVSEM is equivalent to sys_exit(). 2059 */ 2060 exit_sem(current); 2061 } 2062 if (unshare_flags & CLONE_NEWIPC) { 2063 /* Orphan segments in old ns (see sem above). */ 2064 exit_shm(current); 2065 shm_init_task(current); 2066 } 2067 2068 if (new_nsproxy) 2069 switch_task_namespaces(current, new_nsproxy); 2070 2071 task_lock(current); 2072 2073 if (new_fs) { 2074 fs = current->fs; 2075 spin_lock(&fs->lock); 2076 current->fs = new_fs; 2077 if (--fs->users) 2078 new_fs = NULL; 2079 else 2080 new_fs = fs; 2081 spin_unlock(&fs->lock); 2082 } 2083 2084 if (new_fd) { 2085 fd = current->files; 2086 current->files = new_fd; 2087 new_fd = fd; 2088 } 2089 2090 task_unlock(current); 2091 2092 if (new_cred) { 2093 /* Install the new user namespace */ 2094 commit_creds(new_cred); 2095 new_cred = NULL; 2096 } 2097 } 2098 2099 bad_unshare_cleanup_cred: 2100 if (new_cred) 2101 put_cred(new_cred); 2102 bad_unshare_cleanup_fd: 2103 if (new_fd) 2104 put_files_struct(new_fd); 2105 2106 bad_unshare_cleanup_fs: 2107 if (new_fs) 2108 free_fs_struct(new_fs); 2109 2110 bad_unshare_out: 2111 return err; 2112 } 2113 2114 /* 2115 * Helper to unshare the files of the current task. 2116 * We don't want to expose copy_files internals to 2117 * the exec layer of the kernel. 2118 */ 2119 2120 int unshare_files(struct files_struct **displaced) 2121 { 2122 struct task_struct *task = current; 2123 struct files_struct *copy = NULL; 2124 int error; 2125 2126 error = unshare_fd(CLONE_FILES, ©); 2127 if (error || !copy) { 2128 *displaced = NULL; 2129 return error; 2130 } 2131 *displaced = task->files; 2132 task_lock(task); 2133 task->files = copy; 2134 task_unlock(task); 2135 return 0; 2136 } 2137 2138 int sysctl_max_threads(struct ctl_table *table, int write, 2139 void __user *buffer, size_t *lenp, loff_t *ppos) 2140 { 2141 struct ctl_table t; 2142 int ret; 2143 int threads = max_threads; 2144 int min = MIN_THREADS; 2145 int max = MAX_THREADS; 2146 2147 t = *table; 2148 t.data = &threads; 2149 t.extra1 = &min; 2150 t.extra2 = &max; 2151 2152 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); 2153 if (ret || !write) 2154 return ret; 2155 2156 set_max_threads(threads); 2157 2158 return 0; 2159 } 2160