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