| 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/nsproxy.h> |
| 32 | #include <linux/capability.h> |
| 33 | #include <linux/cpu.h> |
| 34 | #include <linux/cgroup.h> |
| 35 | #include <linux/security.h> |
| 36 | #include <linux/hugetlb.h> |
| 37 | #include <linux/swap.h> |
| 38 | #include <linux/syscalls.h> |
| 39 | #include <linux/jiffies.h> |
| 40 | #include <linux/tracehook.h> |
| 41 | #include <linux/futex.h> |
| 42 | #include <linux/compat.h> |
| 43 | #include <linux/task_io_accounting_ops.h> |
| 44 | #include <linux/rcupdate.h> |
| 45 | #include <linux/ptrace.h> |
| 46 | #include <linux/mount.h> |
| 47 | #include <linux/audit.h> |
| 48 | #include <linux/memcontrol.h> |
| 49 | #include <linux/ftrace.h> |
| 50 | #include <linux/profile.h> |
| 51 | #include <linux/rmap.h> |
| 52 | #include <linux/ksm.h> |
| 53 | #include <linux/acct.h> |
| 54 | #include <linux/tsacct_kern.h> |
| 55 | #include <linux/cn_proc.h> |
| 56 | #include <linux/freezer.h> |
| 57 | #include <linux/delayacct.h> |
| 58 | #include <linux/taskstats_kern.h> |
| 59 | #include <linux/random.h> |
| 60 | #include <linux/tty.h> |
| 61 | #include <linux/proc_fs.h> |
| 62 | #include <linux/blkdev.h> |
| 63 | #include <linux/fs_struct.h> |
| 64 | #include <linux/magic.h> |
| 65 | #include <linux/perf_event.h> |
| 66 | #include <linux/posix-timers.h> |
| 67 | #include <linux/user-return-notifier.h> |
| 68 | #include <linux/oom.h> |
| 69 | |
| 70 | #include <asm/pgtable.h> |
| 71 | #include <asm/pgalloc.h> |
| 72 | #include <asm/uaccess.h> |
| 73 | #include <asm/mmu_context.h> |
| 74 | #include <asm/cacheflush.h> |
| 75 | #include <asm/tlbflush.h> |
| 76 | |
| 77 | #include <trace/events/sched.h> |
| 78 | |
| 79 | /* |
| 80 | * Protected counters by write_lock_irq(&tasklist_lock) |
| 81 | */ |
| 82 | unsigned long total_forks; /* Handle normal Linux uptimes. */ |
| 83 | int nr_threads; /* The idle threads do not count.. */ |
| 84 | |
| 85 | int max_threads; /* tunable limit on nr_threads */ |
| 86 | |
| 87 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
| 88 | |
| 89 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
| 90 | |
| 91 | #ifdef CONFIG_PROVE_RCU |
| 92 | int lockdep_tasklist_lock_is_held(void) |
| 93 | { |
| 94 | return lockdep_is_held(&tasklist_lock); |
| 95 | } |
| 96 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
| 97 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
| 98 | |
| 99 | int nr_processes(void) |
| 100 | { |
| 101 | int cpu; |
| 102 | int total = 0; |
| 103 | |
| 104 | for_each_possible_cpu(cpu) |
| 105 | total += per_cpu(process_counts, cpu); |
| 106 | |
| 107 | return total; |
| 108 | } |
| 109 | |
| 110 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
| 111 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) |
| 112 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) |
| 113 | static struct kmem_cache *task_struct_cachep; |
| 114 | #endif |
| 115 | |
| 116 | #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR |
| 117 | static inline struct thread_info *alloc_thread_info(struct task_struct *tsk) |
| 118 | { |
| 119 | #ifdef CONFIG_DEBUG_STACK_USAGE |
| 120 | gfp_t mask = GFP_KERNEL | __GFP_ZERO; |
| 121 | #else |
| 122 | gfp_t mask = GFP_KERNEL; |
| 123 | #endif |
| 124 | return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); |
| 125 | } |
| 126 | |
| 127 | static inline void free_thread_info(struct thread_info *ti) |
| 128 | { |
| 129 | free_pages((unsigned long)ti, THREAD_SIZE_ORDER); |
| 130 | } |
| 131 | #endif |
| 132 | |
| 133 | /* SLAB cache for signal_struct structures (tsk->signal) */ |
| 134 | static struct kmem_cache *signal_cachep; |
| 135 | |
| 136 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
| 137 | struct kmem_cache *sighand_cachep; |
| 138 | |
| 139 | /* SLAB cache for files_struct structures (tsk->files) */ |
| 140 | struct kmem_cache *files_cachep; |
| 141 | |
| 142 | /* SLAB cache for fs_struct structures (tsk->fs) */ |
| 143 | struct kmem_cache *fs_cachep; |
| 144 | |
| 145 | /* SLAB cache for vm_area_struct structures */ |
| 146 | struct kmem_cache *vm_area_cachep; |
| 147 | |
| 148 | /* SLAB cache for mm_struct structures (tsk->mm) */ |
| 149 | static struct kmem_cache *mm_cachep; |
| 150 | |
| 151 | static void account_kernel_stack(struct thread_info *ti, int account) |
| 152 | { |
| 153 | struct zone *zone = page_zone(virt_to_page(ti)); |
| 154 | |
| 155 | mod_zone_page_state(zone, NR_KERNEL_STACK, account); |
| 156 | } |
| 157 | |
| 158 | void free_task(struct task_struct *tsk) |
| 159 | { |
| 160 | prop_local_destroy_single(&tsk->dirties); |
| 161 | account_kernel_stack(tsk->stack, -1); |
| 162 | free_thread_info(tsk->stack); |
| 163 | rt_mutex_debug_task_free(tsk); |
| 164 | ftrace_graph_exit_task(tsk); |
| 165 | free_task_struct(tsk); |
| 166 | } |
| 167 | EXPORT_SYMBOL(free_task); |
| 168 | |
| 169 | static inline void free_signal_struct(struct signal_struct *sig) |
| 170 | { |
| 171 | taskstats_tgid_free(sig); |
| 172 | kmem_cache_free(signal_cachep, sig); |
| 173 | } |
| 174 | |
| 175 | static inline void put_signal_struct(struct signal_struct *sig) |
| 176 | { |
| 177 | if (atomic_dec_and_test(&sig->sigcnt)) { |
| 178 | sched_autogroup_exit(sig); |
| 179 | free_signal_struct(sig); |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | void __put_task_struct(struct task_struct *tsk) |
| 184 | { |
| 185 | WARN_ON(!tsk->exit_state); |
| 186 | WARN_ON(atomic_read(&tsk->usage)); |
| 187 | WARN_ON(tsk == current); |
| 188 | |
| 189 | exit_creds(tsk); |
| 190 | delayacct_tsk_free(tsk); |
| 191 | put_signal_struct(tsk->signal); |
| 192 | |
| 193 | if (!profile_handoff_task(tsk)) |
| 194 | free_task(tsk); |
| 195 | } |
| 196 | |
| 197 | /* |
| 198 | * macro override instead of weak attribute alias, to workaround |
| 199 | * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. |
| 200 | */ |
| 201 | #ifndef arch_task_cache_init |
| 202 | #define arch_task_cache_init() |
| 203 | #endif |
| 204 | |
| 205 | void __init fork_init(unsigned long mempages) |
| 206 | { |
| 207 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
| 208 | #ifndef ARCH_MIN_TASKALIGN |
| 209 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES |
| 210 | #endif |
| 211 | /* create a slab on which task_structs can be allocated */ |
| 212 | task_struct_cachep = |
| 213 | kmem_cache_create("task_struct", sizeof(struct task_struct), |
| 214 | ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); |
| 215 | #endif |
| 216 | |
| 217 | /* do the arch specific task caches init */ |
| 218 | arch_task_cache_init(); |
| 219 | |
| 220 | /* |
| 221 | * The default maximum number of threads is set to a safe |
| 222 | * value: the thread structures can take up at most half |
| 223 | * of memory. |
| 224 | */ |
| 225 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); |
| 226 | |
| 227 | /* |
| 228 | * we need to allow at least 20 threads to boot a system |
| 229 | */ |
| 230 | if(max_threads < 20) |
| 231 | max_threads = 20; |
| 232 | |
| 233 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
| 234 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
| 235 | init_task.signal->rlim[RLIMIT_SIGPENDING] = |
| 236 | init_task.signal->rlim[RLIMIT_NPROC]; |
| 237 | } |
| 238 | |
| 239 | int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, |
| 240 | struct task_struct *src) |
| 241 | { |
| 242 | *dst = *src; |
| 243 | return 0; |
| 244 | } |
| 245 | |
| 246 | static struct task_struct *dup_task_struct(struct task_struct *orig) |
| 247 | { |
| 248 | struct task_struct *tsk; |
| 249 | struct thread_info *ti; |
| 250 | unsigned long *stackend; |
| 251 | |
| 252 | int err; |
| 253 | |
| 254 | prepare_to_copy(orig); |
| 255 | |
| 256 | tsk = alloc_task_struct(); |
| 257 | if (!tsk) |
| 258 | return NULL; |
| 259 | |
| 260 | ti = alloc_thread_info(tsk); |
| 261 | if (!ti) { |
| 262 | free_task_struct(tsk); |
| 263 | return NULL; |
| 264 | } |
| 265 | |
| 266 | err = arch_dup_task_struct(tsk, orig); |
| 267 | if (err) |
| 268 | goto out; |
| 269 | |
| 270 | tsk->stack = ti; |
| 271 | |
| 272 | err = prop_local_init_single(&tsk->dirties); |
| 273 | if (err) |
| 274 | goto out; |
| 275 | |
| 276 | setup_thread_stack(tsk, orig); |
| 277 | clear_user_return_notifier(tsk); |
| 278 | clear_tsk_need_resched(tsk); |
| 279 | stackend = end_of_stack(tsk); |
| 280 | *stackend = STACK_END_MAGIC; /* for overflow detection */ |
| 281 | |
| 282 | #ifdef CONFIG_CC_STACKPROTECTOR |
| 283 | tsk->stack_canary = get_random_int(); |
| 284 | #endif |
| 285 | |
| 286 | /* One for us, one for whoever does the "release_task()" (usually parent) */ |
| 287 | atomic_set(&tsk->usage,2); |
| 288 | atomic_set(&tsk->fs_excl, 0); |
| 289 | #ifdef CONFIG_BLK_DEV_IO_TRACE |
| 290 | tsk->btrace_seq = 0; |
| 291 | #endif |
| 292 | tsk->splice_pipe = NULL; |
| 293 | |
| 294 | account_kernel_stack(ti, 1); |
| 295 | |
| 296 | return tsk; |
| 297 | |
| 298 | out: |
| 299 | free_thread_info(ti); |
| 300 | free_task_struct(tsk); |
| 301 | return NULL; |
| 302 | } |
| 303 | |
| 304 | #ifdef CONFIG_MMU |
| 305 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
| 306 | { |
| 307 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
| 308 | struct rb_node **rb_link, *rb_parent; |
| 309 | int retval; |
| 310 | unsigned long charge; |
| 311 | struct mempolicy *pol; |
| 312 | |
| 313 | down_write(&oldmm->mmap_sem); |
| 314 | flush_cache_dup_mm(oldmm); |
| 315 | /* |
| 316 | * Not linked in yet - no deadlock potential: |
| 317 | */ |
| 318 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); |
| 319 | |
| 320 | mm->locked_vm = 0; |
| 321 | mm->mmap = NULL; |
| 322 | mm->mmap_cache = NULL; |
| 323 | mm->free_area_cache = oldmm->mmap_base; |
| 324 | mm->cached_hole_size = ~0UL; |
| 325 | mm->map_count = 0; |
| 326 | cpumask_clear(mm_cpumask(mm)); |
| 327 | mm->mm_rb = RB_ROOT; |
| 328 | rb_link = &mm->mm_rb.rb_node; |
| 329 | rb_parent = NULL; |
| 330 | pprev = &mm->mmap; |
| 331 | retval = ksm_fork(mm, oldmm); |
| 332 | if (retval) |
| 333 | goto out; |
| 334 | |
| 335 | prev = NULL; |
| 336 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
| 337 | struct file *file; |
| 338 | |
| 339 | if (mpnt->vm_flags & VM_DONTCOPY) { |
| 340 | long pages = vma_pages(mpnt); |
| 341 | mm->total_vm -= pages; |
| 342 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
| 343 | -pages); |
| 344 | continue; |
| 345 | } |
| 346 | charge = 0; |
| 347 | if (mpnt->vm_flags & VM_ACCOUNT) { |
| 348 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; |
| 349 | if (security_vm_enough_memory(len)) |
| 350 | goto fail_nomem; |
| 351 | charge = len; |
| 352 | } |
| 353 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| 354 | if (!tmp) |
| 355 | goto fail_nomem; |
| 356 | *tmp = *mpnt; |
| 357 | INIT_LIST_HEAD(&tmp->anon_vma_chain); |
| 358 | pol = mpol_dup(vma_policy(mpnt)); |
| 359 | retval = PTR_ERR(pol); |
| 360 | if (IS_ERR(pol)) |
| 361 | goto fail_nomem_policy; |
| 362 | vma_set_policy(tmp, pol); |
| 363 | tmp->vm_mm = mm; |
| 364 | if (anon_vma_fork(tmp, mpnt)) |
| 365 | goto fail_nomem_anon_vma_fork; |
| 366 | tmp->vm_flags &= ~VM_LOCKED; |
| 367 | tmp->vm_next = tmp->vm_prev = NULL; |
| 368 | file = tmp->vm_file; |
| 369 | if (file) { |
| 370 | struct inode *inode = file->f_path.dentry->d_inode; |
| 371 | struct address_space *mapping = file->f_mapping; |
| 372 | |
| 373 | get_file(file); |
| 374 | if (tmp->vm_flags & VM_DENYWRITE) |
| 375 | atomic_dec(&inode->i_writecount); |
| 376 | spin_lock(&mapping->i_mmap_lock); |
| 377 | if (tmp->vm_flags & VM_SHARED) |
| 378 | mapping->i_mmap_writable++; |
| 379 | tmp->vm_truncate_count = mpnt->vm_truncate_count; |
| 380 | flush_dcache_mmap_lock(mapping); |
| 381 | /* insert tmp into the share list, just after mpnt */ |
| 382 | vma_prio_tree_add(tmp, mpnt); |
| 383 | flush_dcache_mmap_unlock(mapping); |
| 384 | spin_unlock(&mapping->i_mmap_lock); |
| 385 | } |
| 386 | |
| 387 | /* |
| 388 | * Clear hugetlb-related page reserves for children. This only |
| 389 | * affects MAP_PRIVATE mappings. Faults generated by the child |
| 390 | * are not guaranteed to succeed, even if read-only |
| 391 | */ |
| 392 | if (is_vm_hugetlb_page(tmp)) |
| 393 | reset_vma_resv_huge_pages(tmp); |
| 394 | |
| 395 | /* |
| 396 | * Link in the new vma and copy the page table entries. |
| 397 | */ |
| 398 | *pprev = tmp; |
| 399 | pprev = &tmp->vm_next; |
| 400 | tmp->vm_prev = prev; |
| 401 | prev = tmp; |
| 402 | |
| 403 | __vma_link_rb(mm, tmp, rb_link, rb_parent); |
| 404 | rb_link = &tmp->vm_rb.rb_right; |
| 405 | rb_parent = &tmp->vm_rb; |
| 406 | |
| 407 | mm->map_count++; |
| 408 | retval = copy_page_range(mm, oldmm, mpnt); |
| 409 | |
| 410 | if (tmp->vm_ops && tmp->vm_ops->open) |
| 411 | tmp->vm_ops->open(tmp); |
| 412 | |
| 413 | if (retval) |
| 414 | goto out; |
| 415 | } |
| 416 | /* a new mm has just been created */ |
| 417 | arch_dup_mmap(oldmm, mm); |
| 418 | retval = 0; |
| 419 | out: |
| 420 | up_write(&mm->mmap_sem); |
| 421 | flush_tlb_mm(oldmm); |
| 422 | up_write(&oldmm->mmap_sem); |
| 423 | return retval; |
| 424 | fail_nomem_anon_vma_fork: |
| 425 | mpol_put(pol); |
| 426 | fail_nomem_policy: |
| 427 | kmem_cache_free(vm_area_cachep, tmp); |
| 428 | fail_nomem: |
| 429 | retval = -ENOMEM; |
| 430 | vm_unacct_memory(charge); |
| 431 | goto out; |
| 432 | } |
| 433 | |
| 434 | static inline int mm_alloc_pgd(struct mm_struct * mm) |
| 435 | { |
| 436 | mm->pgd = pgd_alloc(mm); |
| 437 | if (unlikely(!mm->pgd)) |
| 438 | return -ENOMEM; |
| 439 | return 0; |
| 440 | } |
| 441 | |
| 442 | static inline void mm_free_pgd(struct mm_struct * mm) |
| 443 | { |
| 444 | pgd_free(mm, mm->pgd); |
| 445 | } |
| 446 | #else |
| 447 | #define dup_mmap(mm, oldmm) (0) |
| 448 | #define mm_alloc_pgd(mm) (0) |
| 449 | #define mm_free_pgd(mm) |
| 450 | #endif /* CONFIG_MMU */ |
| 451 | |
| 452 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
| 453 | |
| 454 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
| 455 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
| 456 | |
| 457 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
| 458 | |
| 459 | static int __init coredump_filter_setup(char *s) |
| 460 | { |
| 461 | default_dump_filter = |
| 462 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
| 463 | MMF_DUMP_FILTER_MASK; |
| 464 | return 1; |
| 465 | } |
| 466 | |
| 467 | __setup("coredump_filter=", coredump_filter_setup); |
| 468 | |
| 469 | #include <linux/init_task.h> |
| 470 | |
| 471 | static void mm_init_aio(struct mm_struct *mm) |
| 472 | { |
| 473 | #ifdef CONFIG_AIO |
| 474 | spin_lock_init(&mm->ioctx_lock); |
| 475 | INIT_HLIST_HEAD(&mm->ioctx_list); |
| 476 | #endif |
| 477 | } |
| 478 | |
| 479 | static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) |
| 480 | { |
| 481 | atomic_set(&mm->mm_users, 1); |
| 482 | atomic_set(&mm->mm_count, 1); |
| 483 | init_rwsem(&mm->mmap_sem); |
| 484 | INIT_LIST_HEAD(&mm->mmlist); |
| 485 | mm->flags = (current->mm) ? |
| 486 | (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; |
| 487 | mm->core_state = NULL; |
| 488 | mm->nr_ptes = 0; |
| 489 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
| 490 | spin_lock_init(&mm->page_table_lock); |
| 491 | mm->free_area_cache = TASK_UNMAPPED_BASE; |
| 492 | mm->cached_hole_size = ~0UL; |
| 493 | mm_init_aio(mm); |
| 494 | mm_init_owner(mm, p); |
| 495 | atomic_set(&mm->oom_disable_count, 0); |
| 496 | |
| 497 | if (likely(!mm_alloc_pgd(mm))) { |
| 498 | mm->def_flags = 0; |
| 499 | mmu_notifier_mm_init(mm); |
| 500 | return mm; |
| 501 | } |
| 502 | |
| 503 | free_mm(mm); |
| 504 | return NULL; |
| 505 | } |
| 506 | |
| 507 | /* |
| 508 | * Allocate and initialize an mm_struct. |
| 509 | */ |
| 510 | struct mm_struct * mm_alloc(void) |
| 511 | { |
| 512 | struct mm_struct * mm; |
| 513 | |
| 514 | mm = allocate_mm(); |
| 515 | if (mm) { |
| 516 | memset(mm, 0, sizeof(*mm)); |
| 517 | mm = mm_init(mm, current); |
| 518 | } |
| 519 | return mm; |
| 520 | } |
| 521 | |
| 522 | /* |
| 523 | * Called when the last reference to the mm |
| 524 | * is dropped: either by a lazy thread or by |
| 525 | * mmput. Free the page directory and the mm. |
| 526 | */ |
| 527 | void __mmdrop(struct mm_struct *mm) |
| 528 | { |
| 529 | BUG_ON(mm == &init_mm); |
| 530 | mm_free_pgd(mm); |
| 531 | destroy_context(mm); |
| 532 | mmu_notifier_mm_destroy(mm); |
| 533 | free_mm(mm); |
| 534 | } |
| 535 | EXPORT_SYMBOL_GPL(__mmdrop); |
| 536 | |
| 537 | /* |
| 538 | * Decrement the use count and release all resources for an mm. |
| 539 | */ |
| 540 | void mmput(struct mm_struct *mm) |
| 541 | { |
| 542 | might_sleep(); |
| 543 | |
| 544 | if (atomic_dec_and_test(&mm->mm_users)) { |
| 545 | exit_aio(mm); |
| 546 | ksm_exit(mm); |
| 547 | exit_mmap(mm); |
| 548 | set_mm_exe_file(mm, NULL); |
| 549 | if (!list_empty(&mm->mmlist)) { |
| 550 | spin_lock(&mmlist_lock); |
| 551 | list_del(&mm->mmlist); |
| 552 | spin_unlock(&mmlist_lock); |
| 553 | } |
| 554 | put_swap_token(mm); |
| 555 | if (mm->binfmt) |
| 556 | module_put(mm->binfmt->module); |
| 557 | mmdrop(mm); |
| 558 | } |
| 559 | } |
| 560 | EXPORT_SYMBOL_GPL(mmput); |
| 561 | |
| 562 | /** |
| 563 | * get_task_mm - acquire a reference to the task's mm |
| 564 | * |
| 565 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
| 566 | * this kernel workthread has transiently adopted a user mm with use_mm, |
| 567 | * to do its AIO) is not set and if so returns a reference to it, after |
| 568 | * bumping up the use count. User must release the mm via mmput() |
| 569 | * after use. Typically used by /proc and ptrace. |
| 570 | */ |
| 571 | struct mm_struct *get_task_mm(struct task_struct *task) |
| 572 | { |
| 573 | struct mm_struct *mm; |
| 574 | |
| 575 | task_lock(task); |
| 576 | mm = task->mm; |
| 577 | if (mm) { |
| 578 | if (task->flags & PF_KTHREAD) |
| 579 | mm = NULL; |
| 580 | else |
| 581 | atomic_inc(&mm->mm_users); |
| 582 | } |
| 583 | task_unlock(task); |
| 584 | return mm; |
| 585 | } |
| 586 | EXPORT_SYMBOL_GPL(get_task_mm); |
| 587 | |
| 588 | /* Please note the differences between mmput and mm_release. |
| 589 | * mmput is called whenever we stop holding onto a mm_struct, |
| 590 | * error success whatever. |
| 591 | * |
| 592 | * mm_release is called after a mm_struct has been removed |
| 593 | * from the current process. |
| 594 | * |
| 595 | * This difference is important for error handling, when we |
| 596 | * only half set up a mm_struct for a new process and need to restore |
| 597 | * the old one. Because we mmput the new mm_struct before |
| 598 | * restoring the old one. . . |
| 599 | * Eric Biederman 10 January 1998 |
| 600 | */ |
| 601 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
| 602 | { |
| 603 | struct completion *vfork_done = tsk->vfork_done; |
| 604 | |
| 605 | /* Get rid of any futexes when releasing the mm */ |
| 606 | #ifdef CONFIG_FUTEX |
| 607 | if (unlikely(tsk->robust_list)) { |
| 608 | exit_robust_list(tsk); |
| 609 | tsk->robust_list = NULL; |
| 610 | } |
| 611 | #ifdef CONFIG_COMPAT |
| 612 | if (unlikely(tsk->compat_robust_list)) { |
| 613 | compat_exit_robust_list(tsk); |
| 614 | tsk->compat_robust_list = NULL; |
| 615 | } |
| 616 | #endif |
| 617 | if (unlikely(!list_empty(&tsk->pi_state_list))) |
| 618 | exit_pi_state_list(tsk); |
| 619 | #endif |
| 620 | |
| 621 | /* Get rid of any cached register state */ |
| 622 | deactivate_mm(tsk, mm); |
| 623 | |
| 624 | /* notify parent sleeping on vfork() */ |
| 625 | if (vfork_done) { |
| 626 | tsk->vfork_done = NULL; |
| 627 | complete(vfork_done); |
| 628 | } |
| 629 | |
| 630 | /* |
| 631 | * If we're exiting normally, clear a user-space tid field if |
| 632 | * requested. We leave this alone when dying by signal, to leave |
| 633 | * the value intact in a core dump, and to save the unnecessary |
| 634 | * trouble otherwise. Userland only wants this done for a sys_exit. |
| 635 | */ |
| 636 | if (tsk->clear_child_tid) { |
| 637 | if (!(tsk->flags & PF_SIGNALED) && |
| 638 | atomic_read(&mm->mm_users) > 1) { |
| 639 | /* |
| 640 | * We don't check the error code - if userspace has |
| 641 | * not set up a proper pointer then tough luck. |
| 642 | */ |
| 643 | put_user(0, tsk->clear_child_tid); |
| 644 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, |
| 645 | 1, NULL, NULL, 0); |
| 646 | } |
| 647 | tsk->clear_child_tid = NULL; |
| 648 | } |
| 649 | } |
| 650 | |
| 651 | /* |
| 652 | * Allocate a new mm structure and copy contents from the |
| 653 | * mm structure of the passed in task structure. |
| 654 | */ |
| 655 | struct mm_struct *dup_mm(struct task_struct *tsk) |
| 656 | { |
| 657 | struct mm_struct *mm, *oldmm = current->mm; |
| 658 | int err; |
| 659 | |
| 660 | if (!oldmm) |
| 661 | return NULL; |
| 662 | |
| 663 | mm = allocate_mm(); |
| 664 | if (!mm) |
| 665 | goto fail_nomem; |
| 666 | |
| 667 | memcpy(mm, oldmm, sizeof(*mm)); |
| 668 | |
| 669 | /* Initializing for Swap token stuff */ |
| 670 | mm->token_priority = 0; |
| 671 | mm->last_interval = 0; |
| 672 | |
| 673 | if (!mm_init(mm, tsk)) |
| 674 | goto fail_nomem; |
| 675 | |
| 676 | if (init_new_context(tsk, mm)) |
| 677 | goto fail_nocontext; |
| 678 | |
| 679 | dup_mm_exe_file(oldmm, mm); |
| 680 | |
| 681 | err = dup_mmap(mm, oldmm); |
| 682 | if (err) |
| 683 | goto free_pt; |
| 684 | |
| 685 | mm->hiwater_rss = get_mm_rss(mm); |
| 686 | mm->hiwater_vm = mm->total_vm; |
| 687 | |
| 688 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
| 689 | goto free_pt; |
| 690 | |
| 691 | return mm; |
| 692 | |
| 693 | free_pt: |
| 694 | /* don't put binfmt in mmput, we haven't got module yet */ |
| 695 | mm->binfmt = NULL; |
| 696 | mmput(mm); |
| 697 | |
| 698 | fail_nomem: |
| 699 | return NULL; |
| 700 | |
| 701 | fail_nocontext: |
| 702 | /* |
| 703 | * If init_new_context() failed, we cannot use mmput() to free the mm |
| 704 | * because it calls destroy_context() |
| 705 | */ |
| 706 | mm_free_pgd(mm); |
| 707 | free_mm(mm); |
| 708 | return NULL; |
| 709 | } |
| 710 | |
| 711 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) |
| 712 | { |
| 713 | struct mm_struct * mm, *oldmm; |
| 714 | int retval; |
| 715 | |
| 716 | tsk->min_flt = tsk->maj_flt = 0; |
| 717 | tsk->nvcsw = tsk->nivcsw = 0; |
| 718 | #ifdef CONFIG_DETECT_HUNG_TASK |
| 719 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
| 720 | #endif |
| 721 | |
| 722 | tsk->mm = NULL; |
| 723 | tsk->active_mm = NULL; |
| 724 | |
| 725 | /* |
| 726 | * Are we cloning a kernel thread? |
| 727 | * |
| 728 | * We need to steal a active VM for that.. |
| 729 | */ |
| 730 | oldmm = current->mm; |
| 731 | if (!oldmm) |
| 732 | return 0; |
| 733 | |
| 734 | if (clone_flags & CLONE_VM) { |
| 735 | atomic_inc(&oldmm->mm_users); |
| 736 | mm = oldmm; |
| 737 | goto good_mm; |
| 738 | } |
| 739 | |
| 740 | retval = -ENOMEM; |
| 741 | mm = dup_mm(tsk); |
| 742 | if (!mm) |
| 743 | goto fail_nomem; |
| 744 | |
| 745 | good_mm: |
| 746 | /* Initializing for Swap token stuff */ |
| 747 | mm->token_priority = 0; |
| 748 | mm->last_interval = 0; |
| 749 | if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) |
| 750 | atomic_inc(&mm->oom_disable_count); |
| 751 | |
| 752 | tsk->mm = mm; |
| 753 | tsk->active_mm = mm; |
| 754 | return 0; |
| 755 | |
| 756 | fail_nomem: |
| 757 | return retval; |
| 758 | } |
| 759 | |
| 760 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
| 761 | { |
| 762 | struct fs_struct *fs = current->fs; |
| 763 | if (clone_flags & CLONE_FS) { |
| 764 | /* tsk->fs is already what we want */ |
| 765 | spin_lock(&fs->lock); |
| 766 | if (fs->in_exec) { |
| 767 | spin_unlock(&fs->lock); |
| 768 | return -EAGAIN; |
| 769 | } |
| 770 | fs->users++; |
| 771 | spin_unlock(&fs->lock); |
| 772 | return 0; |
| 773 | } |
| 774 | tsk->fs = copy_fs_struct(fs); |
| 775 | if (!tsk->fs) |
| 776 | return -ENOMEM; |
| 777 | return 0; |
| 778 | } |
| 779 | |
| 780 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) |
| 781 | { |
| 782 | struct files_struct *oldf, *newf; |
| 783 | int error = 0; |
| 784 | |
| 785 | /* |
| 786 | * A background process may not have any files ... |
| 787 | */ |
| 788 | oldf = current->files; |
| 789 | if (!oldf) |
| 790 | goto out; |
| 791 | |
| 792 | if (clone_flags & CLONE_FILES) { |
| 793 | atomic_inc(&oldf->count); |
| 794 | goto out; |
| 795 | } |
| 796 | |
| 797 | newf = dup_fd(oldf, &error); |
| 798 | if (!newf) |
| 799 | goto out; |
| 800 | |
| 801 | tsk->files = newf; |
| 802 | error = 0; |
| 803 | out: |
| 804 | return error; |
| 805 | } |
| 806 | |
| 807 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) |
| 808 | { |
| 809 | #ifdef CONFIG_BLOCK |
| 810 | struct io_context *ioc = current->io_context; |
| 811 | |
| 812 | if (!ioc) |
| 813 | return 0; |
| 814 | /* |
| 815 | * Share io context with parent, if CLONE_IO is set |
| 816 | */ |
| 817 | if (clone_flags & CLONE_IO) { |
| 818 | tsk->io_context = ioc_task_link(ioc); |
| 819 | if (unlikely(!tsk->io_context)) |
| 820 | return -ENOMEM; |
| 821 | } else if (ioprio_valid(ioc->ioprio)) { |
| 822 | tsk->io_context = alloc_io_context(GFP_KERNEL, -1); |
| 823 | if (unlikely(!tsk->io_context)) |
| 824 | return -ENOMEM; |
| 825 | |
| 826 | tsk->io_context->ioprio = ioc->ioprio; |
| 827 | } |
| 828 | #endif |
| 829 | return 0; |
| 830 | } |
| 831 | |
| 832 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
| 833 | { |
| 834 | struct sighand_struct *sig; |
| 835 | |
| 836 | if (clone_flags & CLONE_SIGHAND) { |
| 837 | atomic_inc(¤t->sighand->count); |
| 838 | return 0; |
| 839 | } |
| 840 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
| 841 | rcu_assign_pointer(tsk->sighand, sig); |
| 842 | if (!sig) |
| 843 | return -ENOMEM; |
| 844 | atomic_set(&sig->count, 1); |
| 845 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
| 846 | return 0; |
| 847 | } |
| 848 | |
| 849 | void __cleanup_sighand(struct sighand_struct *sighand) |
| 850 | { |
| 851 | if (atomic_dec_and_test(&sighand->count)) |
| 852 | kmem_cache_free(sighand_cachep, sighand); |
| 853 | } |
| 854 | |
| 855 | |
| 856 | /* |
| 857 | * Initialize POSIX timer handling for a thread group. |
| 858 | */ |
| 859 | static void posix_cpu_timers_init_group(struct signal_struct *sig) |
| 860 | { |
| 861 | unsigned long cpu_limit; |
| 862 | |
| 863 | /* Thread group counters. */ |
| 864 | thread_group_cputime_init(sig); |
| 865 | |
| 866 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
| 867 | if (cpu_limit != RLIM_INFINITY) { |
| 868 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); |
| 869 | sig->cputimer.running = 1; |
| 870 | } |
| 871 | |
| 872 | /* The timer lists. */ |
| 873 | INIT_LIST_HEAD(&sig->cpu_timers[0]); |
| 874 | INIT_LIST_HEAD(&sig->cpu_timers[1]); |
| 875 | INIT_LIST_HEAD(&sig->cpu_timers[2]); |
| 876 | } |
| 877 | |
| 878 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
| 879 | { |
| 880 | struct signal_struct *sig; |
| 881 | |
| 882 | if (clone_flags & CLONE_THREAD) |
| 883 | return 0; |
| 884 | |
| 885 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
| 886 | tsk->signal = sig; |
| 887 | if (!sig) |
| 888 | return -ENOMEM; |
| 889 | |
| 890 | sig->nr_threads = 1; |
| 891 | atomic_set(&sig->live, 1); |
| 892 | atomic_set(&sig->sigcnt, 1); |
| 893 | init_waitqueue_head(&sig->wait_chldexit); |
| 894 | if (clone_flags & CLONE_NEWPID) |
| 895 | sig->flags |= SIGNAL_UNKILLABLE; |
| 896 | sig->curr_target = tsk; |
| 897 | init_sigpending(&sig->shared_pending); |
| 898 | INIT_LIST_HEAD(&sig->posix_timers); |
| 899 | |
| 900 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 901 | sig->real_timer.function = it_real_fn; |
| 902 | |
| 903 | task_lock(current->group_leader); |
| 904 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
| 905 | task_unlock(current->group_leader); |
| 906 | |
| 907 | posix_cpu_timers_init_group(sig); |
| 908 | |
| 909 | tty_audit_fork(sig); |
| 910 | sched_autogroup_fork(sig); |
| 911 | |
| 912 | sig->oom_adj = current->signal->oom_adj; |
| 913 | sig->oom_score_adj = current->signal->oom_score_adj; |
| 914 | |
| 915 | mutex_init(&sig->cred_guard_mutex); |
| 916 | |
| 917 | return 0; |
| 918 | } |
| 919 | |
| 920 | static void copy_flags(unsigned long clone_flags, struct task_struct *p) |
| 921 | { |
| 922 | unsigned long new_flags = p->flags; |
| 923 | |
| 924 | new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); |
| 925 | new_flags |= PF_FORKNOEXEC; |
| 926 | new_flags |= PF_STARTING; |
| 927 | p->flags = new_flags; |
| 928 | clear_freeze_flag(p); |
| 929 | } |
| 930 | |
| 931 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
| 932 | { |
| 933 | current->clear_child_tid = tidptr; |
| 934 | |
| 935 | return task_pid_vnr(current); |
| 936 | } |
| 937 | |
| 938 | static void rt_mutex_init_task(struct task_struct *p) |
| 939 | { |
| 940 | raw_spin_lock_init(&p->pi_lock); |
| 941 | #ifdef CONFIG_RT_MUTEXES |
| 942 | plist_head_init_raw(&p->pi_waiters, &p->pi_lock); |
| 943 | p->pi_blocked_on = NULL; |
| 944 | #endif |
| 945 | } |
| 946 | |
| 947 | #ifdef CONFIG_MM_OWNER |
| 948 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
| 949 | { |
| 950 | mm->owner = p; |
| 951 | } |
| 952 | #endif /* CONFIG_MM_OWNER */ |
| 953 | |
| 954 | /* |
| 955 | * Initialize POSIX timer handling for a single task. |
| 956 | */ |
| 957 | static void posix_cpu_timers_init(struct task_struct *tsk) |
| 958 | { |
| 959 | tsk->cputime_expires.prof_exp = cputime_zero; |
| 960 | tsk->cputime_expires.virt_exp = cputime_zero; |
| 961 | tsk->cputime_expires.sched_exp = 0; |
| 962 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); |
| 963 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); |
| 964 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); |
| 965 | } |
| 966 | |
| 967 | /* |
| 968 | * This creates a new process as a copy of the old one, |
| 969 | * but does not actually start it yet. |
| 970 | * |
| 971 | * It copies the registers, and all the appropriate |
| 972 | * parts of the process environment (as per the clone |
| 973 | * flags). The actual kick-off is left to the caller. |
| 974 | */ |
| 975 | static struct task_struct *copy_process(unsigned long clone_flags, |
| 976 | unsigned long stack_start, |
| 977 | struct pt_regs *regs, |
| 978 | unsigned long stack_size, |
| 979 | int __user *child_tidptr, |
| 980 | struct pid *pid, |
| 981 | int trace) |
| 982 | { |
| 983 | int retval; |
| 984 | struct task_struct *p; |
| 985 | int cgroup_callbacks_done = 0; |
| 986 | |
| 987 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
| 988 | return ERR_PTR(-EINVAL); |
| 989 | |
| 990 | /* |
| 991 | * Thread groups must share signals as well, and detached threads |
| 992 | * can only be started up within the thread group. |
| 993 | */ |
| 994 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
| 995 | return ERR_PTR(-EINVAL); |
| 996 | |
| 997 | /* |
| 998 | * Shared signal handlers imply shared VM. By way of the above, |
| 999 | * thread groups also imply shared VM. Blocking this case allows |
| 1000 | * for various simplifications in other code. |
| 1001 | */ |
| 1002 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
| 1003 | return ERR_PTR(-EINVAL); |
| 1004 | |
| 1005 | /* |
| 1006 | * Siblings of global init remain as zombies on exit since they are |
| 1007 | * not reaped by their parent (swapper). To solve this and to avoid |
| 1008 | * multi-rooted process trees, prevent global and container-inits |
| 1009 | * from creating siblings. |
| 1010 | */ |
| 1011 | if ((clone_flags & CLONE_PARENT) && |
| 1012 | current->signal->flags & SIGNAL_UNKILLABLE) |
| 1013 | return ERR_PTR(-EINVAL); |
| 1014 | |
| 1015 | retval = security_task_create(clone_flags); |
| 1016 | if (retval) |
| 1017 | goto fork_out; |
| 1018 | |
| 1019 | retval = -ENOMEM; |
| 1020 | p = dup_task_struct(current); |
| 1021 | if (!p) |
| 1022 | goto fork_out; |
| 1023 | |
| 1024 | ftrace_graph_init_task(p); |
| 1025 | |
| 1026 | rt_mutex_init_task(p); |
| 1027 | |
| 1028 | #ifdef CONFIG_PROVE_LOCKING |
| 1029 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); |
| 1030 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
| 1031 | #endif |
| 1032 | retval = -EAGAIN; |
| 1033 | if (atomic_read(&p->real_cred->user->processes) >= |
| 1034 | task_rlimit(p, RLIMIT_NPROC)) { |
| 1035 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && |
| 1036 | p->real_cred->user != INIT_USER) |
| 1037 | goto bad_fork_free; |
| 1038 | } |
| 1039 | |
| 1040 | retval = copy_creds(p, clone_flags); |
| 1041 | if (retval < 0) |
| 1042 | goto bad_fork_free; |
| 1043 | |
| 1044 | /* |
| 1045 | * If multiple threads are within copy_process(), then this check |
| 1046 | * triggers too late. This doesn't hurt, the check is only there |
| 1047 | * to stop root fork bombs. |
| 1048 | */ |
| 1049 | retval = -EAGAIN; |
| 1050 | if (nr_threads >= max_threads) |
| 1051 | goto bad_fork_cleanup_count; |
| 1052 | |
| 1053 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) |
| 1054 | goto bad_fork_cleanup_count; |
| 1055 | |
| 1056 | p->did_exec = 0; |
| 1057 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
| 1058 | copy_flags(clone_flags, p); |
| 1059 | INIT_LIST_HEAD(&p->children); |
| 1060 | INIT_LIST_HEAD(&p->sibling); |
| 1061 | rcu_copy_process(p); |
| 1062 | p->vfork_done = NULL; |
| 1063 | spin_lock_init(&p->alloc_lock); |
| 1064 | |
| 1065 | init_sigpending(&p->pending); |
| 1066 | |
| 1067 | p->utime = cputime_zero; |
| 1068 | p->stime = cputime_zero; |
| 1069 | p->gtime = cputime_zero; |
| 1070 | p->utimescaled = cputime_zero; |
| 1071 | p->stimescaled = cputime_zero; |
| 1072 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING |
| 1073 | p->prev_utime = cputime_zero; |
| 1074 | p->prev_stime = cputime_zero; |
| 1075 | #endif |
| 1076 | #if defined(SPLIT_RSS_COUNTING) |
| 1077 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
| 1078 | #endif |
| 1079 | |
| 1080 | p->default_timer_slack_ns = current->timer_slack_ns; |
| 1081 | |
| 1082 | task_io_accounting_init(&p->ioac); |
| 1083 | acct_clear_integrals(p); |
| 1084 | |
| 1085 | posix_cpu_timers_init(p); |
| 1086 | |
| 1087 | p->lock_depth = -1; /* -1 = no lock */ |
| 1088 | do_posix_clock_monotonic_gettime(&p->start_time); |
| 1089 | p->real_start_time = p->start_time; |
| 1090 | monotonic_to_bootbased(&p->real_start_time); |
| 1091 | p->io_context = NULL; |
| 1092 | p->audit_context = NULL; |
| 1093 | cgroup_fork(p); |
| 1094 | #ifdef CONFIG_NUMA |
| 1095 | p->mempolicy = mpol_dup(p->mempolicy); |
| 1096 | if (IS_ERR(p->mempolicy)) { |
| 1097 | retval = PTR_ERR(p->mempolicy); |
| 1098 | p->mempolicy = NULL; |
| 1099 | goto bad_fork_cleanup_cgroup; |
| 1100 | } |
| 1101 | mpol_fix_fork_child_flag(p); |
| 1102 | #endif |
| 1103 | #ifdef CONFIG_TRACE_IRQFLAGS |
| 1104 | p->irq_events = 0; |
| 1105 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW |
| 1106 | p->hardirqs_enabled = 1; |
| 1107 | #else |
| 1108 | p->hardirqs_enabled = 0; |
| 1109 | #endif |
| 1110 | p->hardirq_enable_ip = 0; |
| 1111 | p->hardirq_enable_event = 0; |
| 1112 | p->hardirq_disable_ip = _THIS_IP_; |
| 1113 | p->hardirq_disable_event = 0; |
| 1114 | p->softirqs_enabled = 1; |
| 1115 | p->softirq_enable_ip = _THIS_IP_; |
| 1116 | p->softirq_enable_event = 0; |
| 1117 | p->softirq_disable_ip = 0; |
| 1118 | p->softirq_disable_event = 0; |
| 1119 | p->hardirq_context = 0; |
| 1120 | p->softirq_context = 0; |
| 1121 | #endif |
| 1122 | #ifdef CONFIG_LOCKDEP |
| 1123 | p->lockdep_depth = 0; /* no locks held yet */ |
| 1124 | p->curr_chain_key = 0; |
| 1125 | p->lockdep_recursion = 0; |
| 1126 | #endif |
| 1127 | |
| 1128 | #ifdef CONFIG_DEBUG_MUTEXES |
| 1129 | p->blocked_on = NULL; /* not blocked yet */ |
| 1130 | #endif |
| 1131 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
| 1132 | p->memcg_batch.do_batch = 0; |
| 1133 | p->memcg_batch.memcg = NULL; |
| 1134 | #endif |
| 1135 | |
| 1136 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
| 1137 | sched_fork(p, clone_flags); |
| 1138 | |
| 1139 | retval = perf_event_init_task(p); |
| 1140 | if (retval) |
| 1141 | goto bad_fork_cleanup_policy; |
| 1142 | |
| 1143 | if ((retval = audit_alloc(p))) |
| 1144 | goto bad_fork_cleanup_policy; |
| 1145 | /* copy all the process information */ |
| 1146 | if ((retval = copy_semundo(clone_flags, p))) |
| 1147 | goto bad_fork_cleanup_audit; |
| 1148 | if ((retval = copy_files(clone_flags, p))) |
| 1149 | goto bad_fork_cleanup_semundo; |
| 1150 | if ((retval = copy_fs(clone_flags, p))) |
| 1151 | goto bad_fork_cleanup_files; |
| 1152 | if ((retval = copy_sighand(clone_flags, p))) |
| 1153 | goto bad_fork_cleanup_fs; |
| 1154 | if ((retval = copy_signal(clone_flags, p))) |
| 1155 | goto bad_fork_cleanup_sighand; |
| 1156 | if ((retval = copy_mm(clone_flags, p))) |
| 1157 | goto bad_fork_cleanup_signal; |
| 1158 | if ((retval = copy_namespaces(clone_flags, p))) |
| 1159 | goto bad_fork_cleanup_mm; |
| 1160 | if ((retval = copy_io(clone_flags, p))) |
| 1161 | goto bad_fork_cleanup_namespaces; |
| 1162 | retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); |
| 1163 | if (retval) |
| 1164 | goto bad_fork_cleanup_io; |
| 1165 | |
| 1166 | if (pid != &init_struct_pid) { |
| 1167 | retval = -ENOMEM; |
| 1168 | pid = alloc_pid(p->nsproxy->pid_ns); |
| 1169 | if (!pid) |
| 1170 | goto bad_fork_cleanup_io; |
| 1171 | |
| 1172 | if (clone_flags & CLONE_NEWPID) { |
| 1173 | retval = pid_ns_prepare_proc(p->nsproxy->pid_ns); |
| 1174 | if (retval < 0) |
| 1175 | goto bad_fork_free_pid; |
| 1176 | } |
| 1177 | } |
| 1178 | |
| 1179 | p->pid = pid_nr(pid); |
| 1180 | p->tgid = p->pid; |
| 1181 | if (clone_flags & CLONE_THREAD) |
| 1182 | p->tgid = current->tgid; |
| 1183 | |
| 1184 | if (current->nsproxy != p->nsproxy) { |
| 1185 | retval = ns_cgroup_clone(p, pid); |
| 1186 | if (retval) |
| 1187 | goto bad_fork_free_pid; |
| 1188 | } |
| 1189 | |
| 1190 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; |
| 1191 | /* |
| 1192 | * Clear TID on mm_release()? |
| 1193 | */ |
| 1194 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; |
| 1195 | #ifdef CONFIG_FUTEX |
| 1196 | p->robust_list = NULL; |
| 1197 | #ifdef CONFIG_COMPAT |
| 1198 | p->compat_robust_list = NULL; |
| 1199 | #endif |
| 1200 | INIT_LIST_HEAD(&p->pi_state_list); |
| 1201 | p->pi_state_cache = NULL; |
| 1202 | #endif |
| 1203 | /* |
| 1204 | * sigaltstack should be cleared when sharing the same VM |
| 1205 | */ |
| 1206 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
| 1207 | p->sas_ss_sp = p->sas_ss_size = 0; |
| 1208 | |
| 1209 | /* |
| 1210 | * Syscall tracing and stepping should be turned off in the |
| 1211 | * child regardless of CLONE_PTRACE. |
| 1212 | */ |
| 1213 | user_disable_single_step(p); |
| 1214 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); |
| 1215 | #ifdef TIF_SYSCALL_EMU |
| 1216 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); |
| 1217 | #endif |
| 1218 | clear_all_latency_tracing(p); |
| 1219 | |
| 1220 | /* ok, now we should be set up.. */ |
| 1221 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); |
| 1222 | p->pdeath_signal = 0; |
| 1223 | p->exit_state = 0; |
| 1224 | |
| 1225 | /* |
| 1226 | * Ok, make it visible to the rest of the system. |
| 1227 | * We dont wake it up yet. |
| 1228 | */ |
| 1229 | p->group_leader = p; |
| 1230 | INIT_LIST_HEAD(&p->thread_group); |
| 1231 | |
| 1232 | /* Now that the task is set up, run cgroup callbacks if |
| 1233 | * necessary. We need to run them before the task is visible |
| 1234 | * on the tasklist. */ |
| 1235 | cgroup_fork_callbacks(p); |
| 1236 | cgroup_callbacks_done = 1; |
| 1237 | |
| 1238 | /* Need tasklist lock for parent etc handling! */ |
| 1239 | write_lock_irq(&tasklist_lock); |
| 1240 | |
| 1241 | /* CLONE_PARENT re-uses the old parent */ |
| 1242 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
| 1243 | p->real_parent = current->real_parent; |
| 1244 | p->parent_exec_id = current->parent_exec_id; |
| 1245 | } else { |
| 1246 | p->real_parent = current; |
| 1247 | p->parent_exec_id = current->self_exec_id; |
| 1248 | } |
| 1249 | |
| 1250 | spin_lock(¤t->sighand->siglock); |
| 1251 | |
| 1252 | /* |
| 1253 | * Process group and session signals need to be delivered to just the |
| 1254 | * parent before the fork or both the parent and the child after the |
| 1255 | * fork. Restart if a signal comes in before we add the new process to |
| 1256 | * it's process group. |
| 1257 | * A fatal signal pending means that current will exit, so the new |
| 1258 | * thread can't slip out of an OOM kill (or normal SIGKILL). |
| 1259 | */ |
| 1260 | recalc_sigpending(); |
| 1261 | if (signal_pending(current)) { |
| 1262 | spin_unlock(¤t->sighand->siglock); |
| 1263 | write_unlock_irq(&tasklist_lock); |
| 1264 | retval = -ERESTARTNOINTR; |
| 1265 | goto bad_fork_free_pid; |
| 1266 | } |
| 1267 | |
| 1268 | if (clone_flags & CLONE_THREAD) { |
| 1269 | current->signal->nr_threads++; |
| 1270 | atomic_inc(¤t->signal->live); |
| 1271 | atomic_inc(¤t->signal->sigcnt); |
| 1272 | p->group_leader = current->group_leader; |
| 1273 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); |
| 1274 | } |
| 1275 | |
| 1276 | if (likely(p->pid)) { |
| 1277 | tracehook_finish_clone(p, clone_flags, trace); |
| 1278 | |
| 1279 | if (thread_group_leader(p)) { |
| 1280 | if (clone_flags & CLONE_NEWPID) |
| 1281 | p->nsproxy->pid_ns->child_reaper = p; |
| 1282 | |
| 1283 | p->signal->leader_pid = pid; |
| 1284 | p->signal->tty = tty_kref_get(current->signal->tty); |
| 1285 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
| 1286 | attach_pid(p, PIDTYPE_SID, task_session(current)); |
| 1287 | list_add_tail(&p->sibling, &p->real_parent->children); |
| 1288 | list_add_tail_rcu(&p->tasks, &init_task.tasks); |
| 1289 | __get_cpu_var(process_counts)++; |
| 1290 | } |
| 1291 | attach_pid(p, PIDTYPE_PID, pid); |
| 1292 | nr_threads++; |
| 1293 | } |
| 1294 | |
| 1295 | total_forks++; |
| 1296 | spin_unlock(¤t->sighand->siglock); |
| 1297 | write_unlock_irq(&tasklist_lock); |
| 1298 | proc_fork_connector(p); |
| 1299 | cgroup_post_fork(p); |
| 1300 | perf_event_fork(p); |
| 1301 | return p; |
| 1302 | |
| 1303 | bad_fork_free_pid: |
| 1304 | if (pid != &init_struct_pid) |
| 1305 | free_pid(pid); |
| 1306 | bad_fork_cleanup_io: |
| 1307 | if (p->io_context) |
| 1308 | exit_io_context(p); |
| 1309 | bad_fork_cleanup_namespaces: |
| 1310 | exit_task_namespaces(p); |
| 1311 | bad_fork_cleanup_mm: |
| 1312 | if (p->mm) { |
| 1313 | task_lock(p); |
| 1314 | if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) |
| 1315 | atomic_dec(&p->mm->oom_disable_count); |
| 1316 | task_unlock(p); |
| 1317 | mmput(p->mm); |
| 1318 | } |
| 1319 | bad_fork_cleanup_signal: |
| 1320 | if (!(clone_flags & CLONE_THREAD)) |
| 1321 | put_signal_struct(p->signal); |
| 1322 | bad_fork_cleanup_sighand: |
| 1323 | __cleanup_sighand(p->sighand); |
| 1324 | bad_fork_cleanup_fs: |
| 1325 | exit_fs(p); /* blocking */ |
| 1326 | bad_fork_cleanup_files: |
| 1327 | exit_files(p); /* blocking */ |
| 1328 | bad_fork_cleanup_semundo: |
| 1329 | exit_sem(p); |
| 1330 | bad_fork_cleanup_audit: |
| 1331 | audit_free(p); |
| 1332 | bad_fork_cleanup_policy: |
| 1333 | perf_event_free_task(p); |
| 1334 | #ifdef CONFIG_NUMA |
| 1335 | mpol_put(p->mempolicy); |
| 1336 | bad_fork_cleanup_cgroup: |
| 1337 | #endif |
| 1338 | cgroup_exit(p, cgroup_callbacks_done); |
| 1339 | delayacct_tsk_free(p); |
| 1340 | module_put(task_thread_info(p)->exec_domain->module); |
| 1341 | bad_fork_cleanup_count: |
| 1342 | atomic_dec(&p->cred->user->processes); |
| 1343 | exit_creds(p); |
| 1344 | bad_fork_free: |
| 1345 | free_task(p); |
| 1346 | fork_out: |
| 1347 | return ERR_PTR(retval); |
| 1348 | } |
| 1349 | |
| 1350 | noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) |
| 1351 | { |
| 1352 | memset(regs, 0, sizeof(struct pt_regs)); |
| 1353 | return regs; |
| 1354 | } |
| 1355 | |
| 1356 | static inline void init_idle_pids(struct pid_link *links) |
| 1357 | { |
| 1358 | enum pid_type type; |
| 1359 | |
| 1360 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
| 1361 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ |
| 1362 | links[type].pid = &init_struct_pid; |
| 1363 | } |
| 1364 | } |
| 1365 | |
| 1366 | struct task_struct * __cpuinit fork_idle(int cpu) |
| 1367 | { |
| 1368 | struct task_struct *task; |
| 1369 | struct pt_regs regs; |
| 1370 | |
| 1371 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, |
| 1372 | &init_struct_pid, 0); |
| 1373 | if (!IS_ERR(task)) { |
| 1374 | init_idle_pids(task->pids); |
| 1375 | init_idle(task, cpu); |
| 1376 | } |
| 1377 | |
| 1378 | return task; |
| 1379 | } |
| 1380 | |
| 1381 | /* |
| 1382 | * Ok, this is the main fork-routine. |
| 1383 | * |
| 1384 | * It copies the process, and if successful kick-starts |
| 1385 | * it and waits for it to finish using the VM if required. |
| 1386 | */ |
| 1387 | long do_fork(unsigned long clone_flags, |
| 1388 | unsigned long stack_start, |
| 1389 | struct pt_regs *regs, |
| 1390 | unsigned long stack_size, |
| 1391 | int __user *parent_tidptr, |
| 1392 | int __user *child_tidptr) |
| 1393 | { |
| 1394 | struct task_struct *p; |
| 1395 | int trace = 0; |
| 1396 | long nr; |
| 1397 | |
| 1398 | /* |
| 1399 | * Do some preliminary argument and permissions checking before we |
| 1400 | * actually start allocating stuff |
| 1401 | */ |
| 1402 | if (clone_flags & CLONE_NEWUSER) { |
| 1403 | if (clone_flags & CLONE_THREAD) |
| 1404 | return -EINVAL; |
| 1405 | /* hopefully this check will go away when userns support is |
| 1406 | * complete |
| 1407 | */ |
| 1408 | if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || |
| 1409 | !capable(CAP_SETGID)) |
| 1410 | return -EPERM; |
| 1411 | } |
| 1412 | |
| 1413 | /* |
| 1414 | * We hope to recycle these flags after 2.6.26 |
| 1415 | */ |
| 1416 | if (unlikely(clone_flags & CLONE_STOPPED)) { |
| 1417 | static int __read_mostly count = 100; |
| 1418 | |
| 1419 | if (count > 0 && printk_ratelimit()) { |
| 1420 | char comm[TASK_COMM_LEN]; |
| 1421 | |
| 1422 | count--; |
| 1423 | printk(KERN_INFO "fork(): process `%s' used deprecated " |
| 1424 | "clone flags 0x%lx\n", |
| 1425 | get_task_comm(comm, current), |
| 1426 | clone_flags & CLONE_STOPPED); |
| 1427 | } |
| 1428 | } |
| 1429 | |
| 1430 | /* |
| 1431 | * When called from kernel_thread, don't do user tracing stuff. |
| 1432 | */ |
| 1433 | if (likely(user_mode(regs))) |
| 1434 | trace = tracehook_prepare_clone(clone_flags); |
| 1435 | |
| 1436 | p = copy_process(clone_flags, stack_start, regs, stack_size, |
| 1437 | child_tidptr, NULL, trace); |
| 1438 | /* |
| 1439 | * Do this prior waking up the new thread - the thread pointer |
| 1440 | * might get invalid after that point, if the thread exits quickly. |
| 1441 | */ |
| 1442 | if (!IS_ERR(p)) { |
| 1443 | struct completion vfork; |
| 1444 | |
| 1445 | trace_sched_process_fork(current, p); |
| 1446 | |
| 1447 | nr = task_pid_vnr(p); |
| 1448 | |
| 1449 | if (clone_flags & CLONE_PARENT_SETTID) |
| 1450 | put_user(nr, parent_tidptr); |
| 1451 | |
| 1452 | if (clone_flags & CLONE_VFORK) { |
| 1453 | p->vfork_done = &vfork; |
| 1454 | init_completion(&vfork); |
| 1455 | } |
| 1456 | |
| 1457 | audit_finish_fork(p); |
| 1458 | tracehook_report_clone(regs, clone_flags, nr, p); |
| 1459 | |
| 1460 | /* |
| 1461 | * We set PF_STARTING at creation in case tracing wants to |
| 1462 | * use this to distinguish a fully live task from one that |
| 1463 | * hasn't gotten to tracehook_report_clone() yet. Now we |
| 1464 | * clear it and set the child going. |
| 1465 | */ |
| 1466 | p->flags &= ~PF_STARTING; |
| 1467 | |
| 1468 | if (unlikely(clone_flags & CLONE_STOPPED)) { |
| 1469 | /* |
| 1470 | * We'll start up with an immediate SIGSTOP. |
| 1471 | */ |
| 1472 | sigaddset(&p->pending.signal, SIGSTOP); |
| 1473 | set_tsk_thread_flag(p, TIF_SIGPENDING); |
| 1474 | __set_task_state(p, TASK_STOPPED); |
| 1475 | } else { |
| 1476 | wake_up_new_task(p, clone_flags); |
| 1477 | } |
| 1478 | |
| 1479 | tracehook_report_clone_complete(trace, regs, |
| 1480 | clone_flags, nr, p); |
| 1481 | |
| 1482 | if (clone_flags & CLONE_VFORK) { |
| 1483 | freezer_do_not_count(); |
| 1484 | wait_for_completion(&vfork); |
| 1485 | freezer_count(); |
| 1486 | tracehook_report_vfork_done(p, nr); |
| 1487 | } |
| 1488 | } else { |
| 1489 | nr = PTR_ERR(p); |
| 1490 | } |
| 1491 | return nr; |
| 1492 | } |
| 1493 | |
| 1494 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
| 1495 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
| 1496 | #endif |
| 1497 | |
| 1498 | static void sighand_ctor(void *data) |
| 1499 | { |
| 1500 | struct sighand_struct *sighand = data; |
| 1501 | |
| 1502 | spin_lock_init(&sighand->siglock); |
| 1503 | init_waitqueue_head(&sighand->signalfd_wqh); |
| 1504 | } |
| 1505 | |
| 1506 | void __init proc_caches_init(void) |
| 1507 | { |
| 1508 | sighand_cachep = kmem_cache_create("sighand_cache", |
| 1509 | sizeof(struct sighand_struct), 0, |
| 1510 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| |
| 1511 | SLAB_NOTRACK, sighand_ctor); |
| 1512 | signal_cachep = kmem_cache_create("signal_cache", |
| 1513 | sizeof(struct signal_struct), 0, |
| 1514 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| 1515 | files_cachep = kmem_cache_create("files_cache", |
| 1516 | sizeof(struct files_struct), 0, |
| 1517 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| 1518 | fs_cachep = kmem_cache_create("fs_cache", |
| 1519 | sizeof(struct fs_struct), 0, |
| 1520 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| 1521 | mm_cachep = kmem_cache_create("mm_struct", |
| 1522 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, |
| 1523 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| 1524 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); |
| 1525 | mmap_init(); |
| 1526 | } |
| 1527 | |
| 1528 | /* |
| 1529 | * Check constraints on flags passed to the unshare system call and |
| 1530 | * force unsharing of additional process context as appropriate. |
| 1531 | */ |
| 1532 | static void check_unshare_flags(unsigned long *flags_ptr) |
| 1533 | { |
| 1534 | /* |
| 1535 | * If unsharing a thread from a thread group, must also |
| 1536 | * unshare vm. |
| 1537 | */ |
| 1538 | if (*flags_ptr & CLONE_THREAD) |
| 1539 | *flags_ptr |= CLONE_VM; |
| 1540 | |
| 1541 | /* |
| 1542 | * If unsharing vm, must also unshare signal handlers. |
| 1543 | */ |
| 1544 | if (*flags_ptr & CLONE_VM) |
| 1545 | *flags_ptr |= CLONE_SIGHAND; |
| 1546 | |
| 1547 | /* |
| 1548 | * If unsharing namespace, must also unshare filesystem information. |
| 1549 | */ |
| 1550 | if (*flags_ptr & CLONE_NEWNS) |
| 1551 | *flags_ptr |= CLONE_FS; |
| 1552 | } |
| 1553 | |
| 1554 | /* |
| 1555 | * Unsharing of tasks created with CLONE_THREAD is not supported yet |
| 1556 | */ |
| 1557 | static int unshare_thread(unsigned long unshare_flags) |
| 1558 | { |
| 1559 | if (unshare_flags & CLONE_THREAD) |
| 1560 | return -EINVAL; |
| 1561 | |
| 1562 | return 0; |
| 1563 | } |
| 1564 | |
| 1565 | /* |
| 1566 | * Unshare the filesystem structure if it is being shared |
| 1567 | */ |
| 1568 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
| 1569 | { |
| 1570 | struct fs_struct *fs = current->fs; |
| 1571 | |
| 1572 | if (!(unshare_flags & CLONE_FS) || !fs) |
| 1573 | return 0; |
| 1574 | |
| 1575 | /* don't need lock here; in the worst case we'll do useless copy */ |
| 1576 | if (fs->users == 1) |
| 1577 | return 0; |
| 1578 | |
| 1579 | *new_fsp = copy_fs_struct(fs); |
| 1580 | if (!*new_fsp) |
| 1581 | return -ENOMEM; |
| 1582 | |
| 1583 | return 0; |
| 1584 | } |
| 1585 | |
| 1586 | /* |
| 1587 | * Unsharing of sighand is not supported yet |
| 1588 | */ |
| 1589 | static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) |
| 1590 | { |
| 1591 | struct sighand_struct *sigh = current->sighand; |
| 1592 | |
| 1593 | if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) |
| 1594 | return -EINVAL; |
| 1595 | else |
| 1596 | return 0; |
| 1597 | } |
| 1598 | |
| 1599 | /* |
| 1600 | * Unshare vm if it is being shared |
| 1601 | */ |
| 1602 | static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) |
| 1603 | { |
| 1604 | struct mm_struct *mm = current->mm; |
| 1605 | |
| 1606 | if ((unshare_flags & CLONE_VM) && |
| 1607 | (mm && atomic_read(&mm->mm_users) > 1)) { |
| 1608 | return -EINVAL; |
| 1609 | } |
| 1610 | |
| 1611 | return 0; |
| 1612 | } |
| 1613 | |
| 1614 | /* |
| 1615 | * Unshare file descriptor table if it is being shared |
| 1616 | */ |
| 1617 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) |
| 1618 | { |
| 1619 | struct files_struct *fd = current->files; |
| 1620 | int error = 0; |
| 1621 | |
| 1622 | if ((unshare_flags & CLONE_FILES) && |
| 1623 | (fd && atomic_read(&fd->count) > 1)) { |
| 1624 | *new_fdp = dup_fd(fd, &error); |
| 1625 | if (!*new_fdp) |
| 1626 | return error; |
| 1627 | } |
| 1628 | |
| 1629 | return 0; |
| 1630 | } |
| 1631 | |
| 1632 | /* |
| 1633 | * unshare allows a process to 'unshare' part of the process |
| 1634 | * context which was originally shared using clone. copy_* |
| 1635 | * functions used by do_fork() cannot be used here directly |
| 1636 | * because they modify an inactive task_struct that is being |
| 1637 | * constructed. Here we are modifying the current, active, |
| 1638 | * task_struct. |
| 1639 | */ |
| 1640 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
| 1641 | { |
| 1642 | int err = 0; |
| 1643 | struct fs_struct *fs, *new_fs = NULL; |
| 1644 | struct sighand_struct *new_sigh = NULL; |
| 1645 | struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; |
| 1646 | struct files_struct *fd, *new_fd = NULL; |
| 1647 | struct nsproxy *new_nsproxy = NULL; |
| 1648 | int do_sysvsem = 0; |
| 1649 | |
| 1650 | check_unshare_flags(&unshare_flags); |
| 1651 | |
| 1652 | /* Return -EINVAL for all unsupported flags */ |
| 1653 | err = -EINVAL; |
| 1654 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
| 1655 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
| 1656 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) |
| 1657 | goto bad_unshare_out; |
| 1658 | |
| 1659 | /* |
| 1660 | * CLONE_NEWIPC must also detach from the undolist: after switching |
| 1661 | * to a new ipc namespace, the semaphore arrays from the old |
| 1662 | * namespace are unreachable. |
| 1663 | */ |
| 1664 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
| 1665 | do_sysvsem = 1; |
| 1666 | if ((err = unshare_thread(unshare_flags))) |
| 1667 | goto bad_unshare_out; |
| 1668 | if ((err = unshare_fs(unshare_flags, &new_fs))) |
| 1669 | goto bad_unshare_cleanup_thread; |
| 1670 | if ((err = unshare_sighand(unshare_flags, &new_sigh))) |
| 1671 | goto bad_unshare_cleanup_fs; |
| 1672 | if ((err = unshare_vm(unshare_flags, &new_mm))) |
| 1673 | goto bad_unshare_cleanup_sigh; |
| 1674 | if ((err = unshare_fd(unshare_flags, &new_fd))) |
| 1675 | goto bad_unshare_cleanup_vm; |
| 1676 | if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, |
| 1677 | new_fs))) |
| 1678 | goto bad_unshare_cleanup_fd; |
| 1679 | |
| 1680 | if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { |
| 1681 | if (do_sysvsem) { |
| 1682 | /* |
| 1683 | * CLONE_SYSVSEM is equivalent to sys_exit(). |
| 1684 | */ |
| 1685 | exit_sem(current); |
| 1686 | } |
| 1687 | |
| 1688 | if (new_nsproxy) { |
| 1689 | switch_task_namespaces(current, new_nsproxy); |
| 1690 | new_nsproxy = NULL; |
| 1691 | } |
| 1692 | |
| 1693 | task_lock(current); |
| 1694 | |
| 1695 | if (new_fs) { |
| 1696 | fs = current->fs; |
| 1697 | spin_lock(&fs->lock); |
| 1698 | current->fs = new_fs; |
| 1699 | if (--fs->users) |
| 1700 | new_fs = NULL; |
| 1701 | else |
| 1702 | new_fs = fs; |
| 1703 | spin_unlock(&fs->lock); |
| 1704 | } |
| 1705 | |
| 1706 | if (new_mm) { |
| 1707 | mm = current->mm; |
| 1708 | active_mm = current->active_mm; |
| 1709 | current->mm = new_mm; |
| 1710 | current->active_mm = new_mm; |
| 1711 | if (current->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) { |
| 1712 | atomic_dec(&mm->oom_disable_count); |
| 1713 | atomic_inc(&new_mm->oom_disable_count); |
| 1714 | } |
| 1715 | activate_mm(active_mm, new_mm); |
| 1716 | new_mm = mm; |
| 1717 | } |
| 1718 | |
| 1719 | if (new_fd) { |
| 1720 | fd = current->files; |
| 1721 | current->files = new_fd; |
| 1722 | new_fd = fd; |
| 1723 | } |
| 1724 | |
| 1725 | task_unlock(current); |
| 1726 | } |
| 1727 | |
| 1728 | if (new_nsproxy) |
| 1729 | put_nsproxy(new_nsproxy); |
| 1730 | |
| 1731 | bad_unshare_cleanup_fd: |
| 1732 | if (new_fd) |
| 1733 | put_files_struct(new_fd); |
| 1734 | |
| 1735 | bad_unshare_cleanup_vm: |
| 1736 | if (new_mm) |
| 1737 | mmput(new_mm); |
| 1738 | |
| 1739 | bad_unshare_cleanup_sigh: |
| 1740 | if (new_sigh) |
| 1741 | if (atomic_dec_and_test(&new_sigh->count)) |
| 1742 | kmem_cache_free(sighand_cachep, new_sigh); |
| 1743 | |
| 1744 | bad_unshare_cleanup_fs: |
| 1745 | if (new_fs) |
| 1746 | free_fs_struct(new_fs); |
| 1747 | |
| 1748 | bad_unshare_cleanup_thread: |
| 1749 | bad_unshare_out: |
| 1750 | return err; |
| 1751 | } |
| 1752 | |
| 1753 | /* |
| 1754 | * Helper to unshare the files of the current task. |
| 1755 | * We don't want to expose copy_files internals to |
| 1756 | * the exec layer of the kernel. |
| 1757 | */ |
| 1758 | |
| 1759 | int unshare_files(struct files_struct **displaced) |
| 1760 | { |
| 1761 | struct task_struct *task = current; |
| 1762 | struct files_struct *copy = NULL; |
| 1763 | int error; |
| 1764 | |
| 1765 | error = unshare_fd(CLONE_FILES, ©); |
| 1766 | if (error || !copy) { |
| 1767 | *displaced = NULL; |
| 1768 | return error; |
| 1769 | } |
| 1770 | *displaced = task->files; |
| 1771 | task_lock(task); |
| 1772 | task->files = copy; |
| 1773 | task_unlock(task); |
| 1774 | return 0; |
| 1775 | } |