| /* |
| * linux/kernel/fork.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| */ |
| |
| /* |
| * 'fork.c' contains the help-routines for the 'fork' system call |
| * (see also entry.S and others). |
| * Fork is rather simple, once you get the hang of it, but the memory |
| * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' |
| */ |
| |
| #include <linux/slab.h> |
| #include <linux/init.h> |
| #include <linux/unistd.h> |
| #include <linux/module.h> |
| #include <linux/vmalloc.h> |
| #include <linux/completion.h> |
| #include <linux/personality.h> |
| #include <linux/mempolicy.h> |
| #include <linux/sem.h> |
| #include <linux/file.h> |
| #include <linux/fdtable.h> |
| #include <linux/iocontext.h> |
| #include <linux/key.h> |
| #include <linux/binfmts.h> |
| #include <linux/mman.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/fs.h> |
| #include <linux/nsproxy.h> |
| #include <linux/capability.h> |
| #include <linux/cpu.h> |
| #include <linux/cgroup.h> |
| #include <linux/security.h> |
| #include <linux/hugetlb.h> |
| #include <linux/seccomp.h> |
| #include <linux/swap.h> |
| #include <linux/syscalls.h> |
| #include <linux/jiffies.h> |
| #include <linux/futex.h> |
| #include <linux/compat.h> |
| #include <linux/kthread.h> |
| #include <linux/task_io_accounting_ops.h> |
| #include <linux/rcupdate.h> |
| #include <linux/ptrace.h> |
| #include <linux/mount.h> |
| #include <linux/audit.h> |
| #include <linux/memcontrol.h> |
| #include <linux/ftrace.h> |
| #include <linux/proc_fs.h> |
| #include <linux/profile.h> |
| #include <linux/rmap.h> |
| #include <linux/ksm.h> |
| #include <linux/acct.h> |
| #include <linux/tsacct_kern.h> |
| #include <linux/cn_proc.h> |
| #include <linux/freezer.h> |
| #include <linux/delayacct.h> |
| #include <linux/taskstats_kern.h> |
| #include <linux/random.h> |
| #include <linux/tty.h> |
| #include <linux/blkdev.h> |
| #include <linux/fs_struct.h> |
| #include <linux/magic.h> |
| #include <linux/perf_event.h> |
| #include <linux/posix-timers.h> |
| #include <linux/user-return-notifier.h> |
| #include <linux/oom.h> |
| #include <linux/khugepaged.h> |
| #include <linux/signalfd.h> |
| #include <linux/uprobes.h> |
| #include <linux/aio.h> |
| |
| #include <asm/pgtable.h> |
| #include <asm/pgalloc.h> |
| #include <asm/uaccess.h> |
| #include <asm/mmu_context.h> |
| #include <asm/cacheflush.h> |
| #include <asm/tlbflush.h> |
| |
| #include <trace/events/sched.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/task.h> |
| |
| /* |
| * Protected counters by write_lock_irq(&tasklist_lock) |
| */ |
| unsigned long total_forks; /* Handle normal Linux uptimes. */ |
| int nr_threads; /* The idle threads do not count.. */ |
| |
| int max_threads; /* tunable limit on nr_threads */ |
| |
| DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
| |
| __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
| |
| #ifdef CONFIG_PROVE_RCU |
| int lockdep_tasklist_lock_is_held(void) |
| { |
| return lockdep_is_held(&tasklist_lock); |
| } |
| EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
| #endif /* #ifdef CONFIG_PROVE_RCU */ |
| |
| int nr_processes(void) |
| { |
| int cpu; |
| int total = 0; |
| |
| for_each_possible_cpu(cpu) |
| total += per_cpu(process_counts, cpu); |
| |
| return total; |
| } |
| |
| void __weak arch_release_task_struct(struct task_struct *tsk) |
| { |
| } |
| |
| #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
| static struct kmem_cache *task_struct_cachep; |
| |
| static inline struct task_struct *alloc_task_struct_node(int node) |
| { |
| return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node); |
| } |
| |
| static inline void free_task_struct(struct task_struct *tsk) |
| { |
| kmem_cache_free(task_struct_cachep, tsk); |
| } |
| #endif |
| |
| void __weak arch_release_thread_info(struct thread_info *ti) |
| { |
| } |
| |
| #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR |
| |
| /* |
| * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a |
| * kmemcache based allocator. |
| */ |
| # if THREAD_SIZE >= PAGE_SIZE |
| static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, |
| int node) |
| { |
| struct page *page = alloc_pages_node(node, THREADINFO_GFP_ACCOUNTED, |
| THREAD_SIZE_ORDER); |
| |
| return page ? page_address(page) : NULL; |
| } |
| |
| static inline void free_thread_info(struct thread_info *ti) |
| { |
| free_memcg_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER); |
| } |
| # else |
| static struct kmem_cache *thread_info_cache; |
| |
| static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, |
| int node) |
| { |
| return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node); |
| } |
| |
| static void free_thread_info(struct thread_info *ti) |
| { |
| kmem_cache_free(thread_info_cache, ti); |
| } |
| |
| void thread_info_cache_init(void) |
| { |
| thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE, |
| THREAD_SIZE, 0, NULL); |
| BUG_ON(thread_info_cache == NULL); |
| } |
| # endif |
| #endif |
| |
| /* SLAB cache for signal_struct structures (tsk->signal) */ |
| static struct kmem_cache *signal_cachep; |
| |
| /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
| struct kmem_cache *sighand_cachep; |
| |
| /* SLAB cache for files_struct structures (tsk->files) */ |
| struct kmem_cache *files_cachep; |
| |
| /* SLAB cache for fs_struct structures (tsk->fs) */ |
| struct kmem_cache *fs_cachep; |
| |
| /* SLAB cache for vm_area_struct structures */ |
| struct kmem_cache *vm_area_cachep; |
| |
| /* SLAB cache for mm_struct structures (tsk->mm) */ |
| static struct kmem_cache *mm_cachep; |
| |
| static void account_kernel_stack(struct thread_info *ti, int account) |
| { |
| struct zone *zone = page_zone(virt_to_page(ti)); |
| |
| mod_zone_page_state(zone, NR_KERNEL_STACK, account); |
| } |
| |
| void free_task(struct task_struct *tsk) |
| { |
| account_kernel_stack(tsk->stack, -1); |
| arch_release_thread_info(tsk->stack); |
| free_thread_info(tsk->stack); |
| rt_mutex_debug_task_free(tsk); |
| ftrace_graph_exit_task(tsk); |
| put_seccomp_filter(tsk); |
| arch_release_task_struct(tsk); |
| free_task_struct(tsk); |
| } |
| EXPORT_SYMBOL(free_task); |
| |
| static inline void free_signal_struct(struct signal_struct *sig) |
| { |
| taskstats_tgid_free(sig); |
| sched_autogroup_exit(sig); |
| kmem_cache_free(signal_cachep, sig); |
| } |
| |
| static inline void put_signal_struct(struct signal_struct *sig) |
| { |
| if (atomic_dec_and_test(&sig->sigcnt)) |
| free_signal_struct(sig); |
| } |
| |
| void __put_task_struct(struct task_struct *tsk) |
| { |
| WARN_ON(!tsk->exit_state); |
| WARN_ON(atomic_read(&tsk->usage)); |
| WARN_ON(tsk == current); |
| |
| security_task_free(tsk); |
| exit_creds(tsk); |
| delayacct_tsk_free(tsk); |
| put_signal_struct(tsk->signal); |
| |
| if (!profile_handoff_task(tsk)) |
| free_task(tsk); |
| } |
| EXPORT_SYMBOL_GPL(__put_task_struct); |
| |
| void __init __weak arch_task_cache_init(void) { } |
| |
| void __init fork_init(unsigned long mempages) |
| { |
| #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR |
| #ifndef ARCH_MIN_TASKALIGN |
| #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES |
| #endif |
| /* create a slab on which task_structs can be allocated */ |
| task_struct_cachep = |
| kmem_cache_create("task_struct", sizeof(struct task_struct), |
| ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); |
| #endif |
| |
| /* do the arch specific task caches init */ |
| arch_task_cache_init(); |
| |
| /* |
| * The default maximum number of threads is set to a safe |
| * value: the thread structures can take up at most half |
| * of memory. |
| */ |
| max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); |
| |
| /* |
| * we need to allow at least 20 threads to boot a system |
| */ |
| if (max_threads < 20) |
| max_threads = 20; |
| |
| init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
| init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
| init_task.signal->rlim[RLIMIT_SIGPENDING] = |
| init_task.signal->rlim[RLIMIT_NPROC]; |
| } |
| |
| int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, |
| struct task_struct *src) |
| { |
| *dst = *src; |
| return 0; |
| } |
| |
| static struct task_struct *dup_task_struct(struct task_struct *orig) |
| { |
| struct task_struct *tsk; |
| struct thread_info *ti; |
| unsigned long *stackend; |
| int node = tsk_fork_get_node(orig); |
| int err; |
| |
| tsk = alloc_task_struct_node(node); |
| if (!tsk) |
| return NULL; |
| |
| ti = alloc_thread_info_node(tsk, node); |
| if (!ti) |
| goto free_tsk; |
| |
| err = arch_dup_task_struct(tsk, orig); |
| if (err) |
| goto free_ti; |
| |
| tsk->stack = ti; |
| |
| setup_thread_stack(tsk, orig); |
| clear_user_return_notifier(tsk); |
| clear_tsk_need_resched(tsk); |
| stackend = end_of_stack(tsk); |
| *stackend = STACK_END_MAGIC; /* for overflow detection */ |
| |
| #ifdef CONFIG_CC_STACKPROTECTOR |
| tsk->stack_canary = get_random_int(); |
| #endif |
| |
| /* |
| * One for us, one for whoever does the "release_task()" (usually |
| * parent) |
| */ |
| atomic_set(&tsk->usage, 2); |
| #ifdef CONFIG_BLK_DEV_IO_TRACE |
| tsk->btrace_seq = 0; |
| #endif |
| tsk->splice_pipe = NULL; |
| tsk->task_frag.page = NULL; |
| |
| account_kernel_stack(ti, 1); |
| |
| return tsk; |
| |
| free_ti: |
| free_thread_info(ti); |
| free_tsk: |
| free_task_struct(tsk); |
| return NULL; |
| } |
| |
| #ifdef CONFIG_MMU |
| static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
| { |
| struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
| struct rb_node **rb_link, *rb_parent; |
| int retval; |
| unsigned long charge; |
| |
| uprobe_start_dup_mmap(); |
| down_write(&oldmm->mmap_sem); |
| flush_cache_dup_mm(oldmm); |
| uprobe_dup_mmap(oldmm, mm); |
| /* |
| * Not linked in yet - no deadlock potential: |
| */ |
| down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); |
| |
| mm->locked_vm = 0; |
| mm->mmap = NULL; |
| mm->mmap_cache = NULL; |
| mm->map_count = 0; |
| cpumask_clear(mm_cpumask(mm)); |
| mm->mm_rb = RB_ROOT; |
| rb_link = &mm->mm_rb.rb_node; |
| rb_parent = NULL; |
| pprev = &mm->mmap; |
| retval = ksm_fork(mm, oldmm); |
| if (retval) |
| goto out; |
| retval = khugepaged_fork(mm, oldmm); |
| if (retval) |
| goto out; |
| |
| prev = NULL; |
| for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
| struct file *file; |
| |
| if (mpnt->vm_flags & VM_DONTCOPY) { |
| vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
| -vma_pages(mpnt)); |
| continue; |
| } |
| charge = 0; |
| if (mpnt->vm_flags & VM_ACCOUNT) { |
| unsigned long len = vma_pages(mpnt); |
| |
| if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ |
| goto fail_nomem; |
| charge = len; |
| } |
| tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
| if (!tmp) |
| goto fail_nomem; |
| *tmp = *mpnt; |
| INIT_LIST_HEAD(&tmp->anon_vma_chain); |
| retval = vma_dup_policy(mpnt, tmp); |
| if (retval) |
| goto fail_nomem_policy; |
| tmp->vm_mm = mm; |
| if (anon_vma_fork(tmp, mpnt)) |
| goto fail_nomem_anon_vma_fork; |
| tmp->vm_flags &= ~VM_LOCKED; |
| tmp->vm_next = tmp->vm_prev = NULL; |
| file = tmp->vm_file; |
| if (file) { |
| struct inode *inode = file_inode(file); |
| struct address_space *mapping = file->f_mapping; |
| |
| get_file(file); |
| if (tmp->vm_flags & VM_DENYWRITE) |
| atomic_dec(&inode->i_writecount); |
| mutex_lock(&mapping->i_mmap_mutex); |
| if (tmp->vm_flags & VM_SHARED) |
| mapping->i_mmap_writable++; |
| flush_dcache_mmap_lock(mapping); |
| /* insert tmp into the share list, just after mpnt */ |
| if (unlikely(tmp->vm_flags & VM_NONLINEAR)) |
| vma_nonlinear_insert(tmp, |
| &mapping->i_mmap_nonlinear); |
| else |
| vma_interval_tree_insert_after(tmp, mpnt, |
| &mapping->i_mmap); |
| flush_dcache_mmap_unlock(mapping); |
| mutex_unlock(&mapping->i_mmap_mutex); |
| } |
| |
| /* |
| * Clear hugetlb-related page reserves for children. This only |
| * affects MAP_PRIVATE mappings. Faults generated by the child |
| * are not guaranteed to succeed, even if read-only |
| */ |
| if (is_vm_hugetlb_page(tmp)) |
| reset_vma_resv_huge_pages(tmp); |
| |
| /* |
| * Link in the new vma and copy the page table entries. |
| */ |
| *pprev = tmp; |
| pprev = &tmp->vm_next; |
| tmp->vm_prev = prev; |
| prev = tmp; |
| |
| __vma_link_rb(mm, tmp, rb_link, rb_parent); |
| rb_link = &tmp->vm_rb.rb_right; |
| rb_parent = &tmp->vm_rb; |
| |
| mm->map_count++; |
| retval = copy_page_range(mm, oldmm, mpnt); |
| |
| if (tmp->vm_ops && tmp->vm_ops->open) |
| tmp->vm_ops->open(tmp); |
| |
| if (retval) |
| goto out; |
| } |
| /* a new mm has just been created */ |
| arch_dup_mmap(oldmm, mm); |
| retval = 0; |
| out: |
| up_write(&mm->mmap_sem); |
| flush_tlb_mm(oldmm); |
| up_write(&oldmm->mmap_sem); |
| uprobe_end_dup_mmap(); |
| return retval; |
| fail_nomem_anon_vma_fork: |
| mpol_put(vma_policy(tmp)); |
| fail_nomem_policy: |
| kmem_cache_free(vm_area_cachep, tmp); |
| fail_nomem: |
| retval = -ENOMEM; |
| vm_unacct_memory(charge); |
| goto out; |
| } |
| |
| static inline int mm_alloc_pgd(struct mm_struct *mm) |
| { |
| mm->pgd = pgd_alloc(mm); |
| if (unlikely(!mm->pgd)) |
| return -ENOMEM; |
| return 0; |
| } |
| |
| static inline void mm_free_pgd(struct mm_struct *mm) |
| { |
| pgd_free(mm, mm->pgd); |
| } |
| #else |
| #define dup_mmap(mm, oldmm) (0) |
| #define mm_alloc_pgd(mm) (0) |
| #define mm_free_pgd(mm) |
| #endif /* CONFIG_MMU */ |
| |
| __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
| |
| #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
| #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
| |
| static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
| |
| static int __init coredump_filter_setup(char *s) |
| { |
| default_dump_filter = |
| (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
| MMF_DUMP_FILTER_MASK; |
| return 1; |
| } |
| |
| __setup("coredump_filter=", coredump_filter_setup); |
| |
| #include <linux/init_task.h> |
| |
| static void mm_init_aio(struct mm_struct *mm) |
| { |
| #ifdef CONFIG_AIO |
| spin_lock_init(&mm->ioctx_lock); |
| mm->ioctx_table = NULL; |
| #endif |
| } |
| |
| static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) |
| { |
| atomic_set(&mm->mm_users, 1); |
| atomic_set(&mm->mm_count, 1); |
| init_rwsem(&mm->mmap_sem); |
| INIT_LIST_HEAD(&mm->mmlist); |
| mm->flags = (current->mm) ? |
| (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; |
| mm->core_state = NULL; |
| atomic_long_set(&mm->nr_ptes, 0); |
| memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
| spin_lock_init(&mm->page_table_lock); |
| mm_init_aio(mm); |
| mm_init_owner(mm, p); |
| clear_tlb_flush_pending(mm); |
| |
| if (likely(!mm_alloc_pgd(mm))) { |
| mm->def_flags = 0; |
| mmu_notifier_mm_init(mm); |
| return mm; |
| } |
| |
| free_mm(mm); |
| return NULL; |
| } |
| |
| static void check_mm(struct mm_struct *mm) |
| { |
| int i; |
| |
| for (i = 0; i < NR_MM_COUNTERS; i++) { |
| long x = atomic_long_read(&mm->rss_stat.count[i]); |
| |
| if (unlikely(x)) |
| printk(KERN_ALERT "BUG: Bad rss-counter state " |
| "mm:%p idx:%d val:%ld\n", mm, i, x); |
| } |
| |
| #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
| VM_BUG_ON(mm->pmd_huge_pte); |
| #endif |
| } |
| |
| /* |
| * Allocate and initialize an mm_struct. |
| */ |
| struct mm_struct *mm_alloc(void) |
| { |
| struct mm_struct *mm; |
| |
| mm = allocate_mm(); |
| if (!mm) |
| return NULL; |
| |
| memset(mm, 0, sizeof(*mm)); |
| mm_init_cpumask(mm); |
| return mm_init(mm, current); |
| } |
| |
| /* |
| * Called when the last reference to the mm |
| * is dropped: either by a lazy thread or by |
| * mmput. Free the page directory and the mm. |
| */ |
| void __mmdrop(struct mm_struct *mm) |
| { |
| BUG_ON(mm == &init_mm); |
| mm_free_pgd(mm); |
| destroy_context(mm); |
| mmu_notifier_mm_destroy(mm); |
| check_mm(mm); |
| free_mm(mm); |
| } |
| EXPORT_SYMBOL_GPL(__mmdrop); |
| |
| /* |
| * Decrement the use count and release all resources for an mm. |
| */ |
| void mmput(struct mm_struct *mm) |
| { |
| might_sleep(); |
| |
| if (atomic_dec_and_test(&mm->mm_users)) { |
| uprobe_clear_state(mm); |
| exit_aio(mm); |
| ksm_exit(mm); |
| khugepaged_exit(mm); /* must run before exit_mmap */ |
| exit_mmap(mm); |
| set_mm_exe_file(mm, NULL); |
| if (!list_empty(&mm->mmlist)) { |
| spin_lock(&mmlist_lock); |
| list_del(&mm->mmlist); |
| spin_unlock(&mmlist_lock); |
| } |
| if (mm->binfmt) |
| module_put(mm->binfmt->module); |
| mmdrop(mm); |
| } |
| } |
| EXPORT_SYMBOL_GPL(mmput); |
| |
| void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) |
| { |
| if (new_exe_file) |
| get_file(new_exe_file); |
| if (mm->exe_file) |
| fput(mm->exe_file); |
| mm->exe_file = new_exe_file; |
| } |
| |
| struct file *get_mm_exe_file(struct mm_struct *mm) |
| { |
| struct file *exe_file; |
| |
| /* We need mmap_sem to protect against races with removal of exe_file */ |
| down_read(&mm->mmap_sem); |
| exe_file = mm->exe_file; |
| if (exe_file) |
| get_file(exe_file); |
| up_read(&mm->mmap_sem); |
| return exe_file; |
| } |
| |
| static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm) |
| { |
| /* It's safe to write the exe_file pointer without exe_file_lock because |
| * this is called during fork when the task is not yet in /proc */ |
| newmm->exe_file = get_mm_exe_file(oldmm); |
| } |
| |
| /** |
| * get_task_mm - acquire a reference to the task's mm |
| * |
| * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
| * this kernel workthread has transiently adopted a user mm with use_mm, |
| * to do its AIO) is not set and if so returns a reference to it, after |
| * bumping up the use count. User must release the mm via mmput() |
| * after use. Typically used by /proc and ptrace. |
| */ |
| struct mm_struct *get_task_mm(struct task_struct *task) |
| { |
| struct mm_struct *mm; |
| |
| task_lock(task); |
| mm = task->mm; |
| if (mm) { |
| if (task->flags & PF_KTHREAD) |
| mm = NULL; |
| else |
| atomic_inc(&mm->mm_users); |
| } |
| task_unlock(task); |
| return mm; |
| } |
| EXPORT_SYMBOL_GPL(get_task_mm); |
| |
| struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) |
| { |
| struct mm_struct *mm; |
| int err; |
| |
| err = mutex_lock_killable(&task->signal->cred_guard_mutex); |
| if (err) |
| return ERR_PTR(err); |
| |
| mm = get_task_mm(task); |
| if (mm && mm != current->mm && |
| !ptrace_may_access(task, mode)) { |
| mmput(mm); |
| mm = ERR_PTR(-EACCES); |
| } |
| mutex_unlock(&task->signal->cred_guard_mutex); |
| |
| return mm; |
| } |
| |
| static void complete_vfork_done(struct task_struct *tsk) |
| { |
| struct completion *vfork; |
| |
| task_lock(tsk); |
| vfork = tsk->vfork_done; |
| if (likely(vfork)) { |
| tsk->vfork_done = NULL; |
| complete(vfork); |
| } |
| task_unlock(tsk); |
| } |
| |
| static int wait_for_vfork_done(struct task_struct *child, |
| struct completion *vfork) |
| { |
| int killed; |
| |
| freezer_do_not_count(); |
| killed = wait_for_completion_killable(vfork); |
| freezer_count(); |
| |
| if (killed) { |
| task_lock(child); |
| child->vfork_done = NULL; |
| task_unlock(child); |
| } |
| |
| put_task_struct(child); |
| return killed; |
| } |
| |
| /* Please note the differences between mmput and mm_release. |
| * mmput is called whenever we stop holding onto a mm_struct, |
| * error success whatever. |
| * |
| * mm_release is called after a mm_struct has been removed |
| * from the current process. |
| * |
| * This difference is important for error handling, when we |
| * only half set up a mm_struct for a new process and need to restore |
| * the old one. Because we mmput the new mm_struct before |
| * restoring the old one. . . |
| * Eric Biederman 10 January 1998 |
| */ |
| void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
| { |
| /* Get rid of any futexes when releasing the mm */ |
| #ifdef CONFIG_FUTEX |
| if (unlikely(tsk->robust_list)) { |
| exit_robust_list(tsk); |
| tsk->robust_list = NULL; |
| } |
| #ifdef CONFIG_COMPAT |
| if (unlikely(tsk->compat_robust_list)) { |
| compat_exit_robust_list(tsk); |
| tsk->compat_robust_list = NULL; |
| } |
| #endif |
| if (unlikely(!list_empty(&tsk->pi_state_list))) |
| exit_pi_state_list(tsk); |
| #endif |
| |
| uprobe_free_utask(tsk); |
| |
| /* Get rid of any cached register state */ |
| deactivate_mm(tsk, mm); |
| |
| /* |
| * If we're exiting normally, clear a user-space tid field if |
| * requested. We leave this alone when dying by signal, to leave |
| * the value intact in a core dump, and to save the unnecessary |
| * trouble, say, a killed vfork parent shouldn't touch this mm. |
| * Userland only wants this done for a sys_exit. |
| */ |
| if (tsk->clear_child_tid) { |
| if (!(tsk->flags & PF_SIGNALED) && |
| atomic_read(&mm->mm_users) > 1) { |
| /* |
| * We don't check the error code - if userspace has |
| * not set up a proper pointer then tough luck. |
| */ |
| put_user(0, tsk->clear_child_tid); |
| sys_futex(tsk->clear_child_tid, FUTEX_WAKE, |
| 1, NULL, NULL, 0); |
| } |
| tsk->clear_child_tid = NULL; |
| } |
| |
| /* |
| * All done, finally we can wake up parent and return this mm to him. |
| * Also kthread_stop() uses this completion for synchronization. |
| */ |
| if (tsk->vfork_done) |
| complete_vfork_done(tsk); |
| } |
| |
| /* |
| * Allocate a new mm structure and copy contents from the |
| * mm structure of the passed in task structure. |
| */ |
| struct mm_struct *dup_mm(struct task_struct *tsk) |
| { |
| struct mm_struct *mm, *oldmm = current->mm; |
| int err; |
| |
| if (!oldmm) |
| return NULL; |
| |
| mm = allocate_mm(); |
| if (!mm) |
| goto fail_nomem; |
| |
| memcpy(mm, oldmm, sizeof(*mm)); |
| mm_init_cpumask(mm); |
| |
| #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS |
| mm->pmd_huge_pte = NULL; |
| #endif |
| if (!mm_init(mm, tsk)) |
| goto fail_nomem; |
| |
| if (init_new_context(tsk, mm)) |
| goto fail_nocontext; |
| |
| dup_mm_exe_file(oldmm, mm); |
| |
| err = dup_mmap(mm, oldmm); |
| if (err) |
| goto free_pt; |
| |
| mm->hiwater_rss = get_mm_rss(mm); |
| mm->hiwater_vm = mm->total_vm; |
| |
| if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
| goto free_pt; |
| |
| return mm; |
| |
| free_pt: |
| /* don't put binfmt in mmput, we haven't got module yet */ |
| mm->binfmt = NULL; |
| mmput(mm); |
| |
| fail_nomem: |
| return NULL; |
| |
| fail_nocontext: |
| /* |
| * If init_new_context() failed, we cannot use mmput() to free the mm |
| * because it calls destroy_context() |
| */ |
| mm_free_pgd(mm); |
| free_mm(mm); |
| return NULL; |
| } |
| |
| static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| struct mm_struct *mm, *oldmm; |
| int retval; |
| |
| tsk->min_flt = tsk->maj_flt = 0; |
| tsk->nvcsw = tsk->nivcsw = 0; |
| #ifdef CONFIG_DETECT_HUNG_TASK |
| tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
| #endif |
| |
| tsk->mm = NULL; |
| tsk->active_mm = NULL; |
| |
| /* |
| * Are we cloning a kernel thread? |
| * |
| * We need to steal a active VM for that.. |
| */ |
| oldmm = current->mm; |
| if (!oldmm) |
| return 0; |
| |
| if (clone_flags & CLONE_VM) { |
| atomic_inc(&oldmm->mm_users); |
| mm = oldmm; |
| goto good_mm; |
| } |
| |
| retval = -ENOMEM; |
| mm = dup_mm(tsk); |
| if (!mm) |
| goto fail_nomem; |
| |
| good_mm: |
| tsk->mm = mm; |
| tsk->active_mm = mm; |
| return 0; |
| |
| fail_nomem: |
| return retval; |
| } |
| |
| static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| struct fs_struct *fs = current->fs; |
| if (clone_flags & CLONE_FS) { |
| /* tsk->fs is already what we want */ |
| spin_lock(&fs->lock); |
| if (fs->in_exec) { |
| spin_unlock(&fs->lock); |
| return -EAGAIN; |
| } |
| fs->users++; |
| spin_unlock(&fs->lock); |
| return 0; |
| } |
| tsk->fs = copy_fs_struct(fs); |
| if (!tsk->fs) |
| return -ENOMEM; |
| return 0; |
| } |
| |
| static int copy_files(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| struct files_struct *oldf, *newf; |
| int error = 0; |
| |
| /* |
| * A background process may not have any files ... |
| */ |
| oldf = current->files; |
| if (!oldf) |
| goto out; |
| |
| if (clone_flags & CLONE_FILES) { |
| atomic_inc(&oldf->count); |
| goto out; |
| } |
| |
| newf = dup_fd(oldf, &error); |
| if (!newf) |
| goto out; |
| |
| tsk->files = newf; |
| error = 0; |
| out: |
| return error; |
| } |
| |
| static int copy_io(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| #ifdef CONFIG_BLOCK |
| struct io_context *ioc = current->io_context; |
| struct io_context *new_ioc; |
| |
| if (!ioc) |
| return 0; |
| /* |
| * Share io context with parent, if CLONE_IO is set |
| */ |
| if (clone_flags & CLONE_IO) { |
| ioc_task_link(ioc); |
| tsk->io_context = ioc; |
| } else if (ioprio_valid(ioc->ioprio)) { |
| new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); |
| if (unlikely(!new_ioc)) |
| return -ENOMEM; |
| |
| new_ioc->ioprio = ioc->ioprio; |
| put_io_context(new_ioc); |
| } |
| #endif |
| return 0; |
| } |
| |
| static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| struct sighand_struct *sig; |
| |
| if (clone_flags & CLONE_SIGHAND) { |
| atomic_inc(¤t->sighand->count); |
| return 0; |
| } |
| sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
| rcu_assign_pointer(tsk->sighand, sig); |
| if (!sig) |
| return -ENOMEM; |
| atomic_set(&sig->count, 1); |
| memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
| return 0; |
| } |
| |
| void __cleanup_sighand(struct sighand_struct *sighand) |
| { |
| if (atomic_dec_and_test(&sighand->count)) { |
| signalfd_cleanup(sighand); |
| kmem_cache_free(sighand_cachep, sighand); |
| } |
| } |
| |
| |
| /* |
| * Initialize POSIX timer handling for a thread group. |
| */ |
| static void posix_cpu_timers_init_group(struct signal_struct *sig) |
| { |
| unsigned long cpu_limit; |
| |
| /* Thread group counters. */ |
| thread_group_cputime_init(sig); |
| |
| cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
| if (cpu_limit != RLIM_INFINITY) { |
| sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); |
| sig->cputimer.running = 1; |
| } |
| |
| /* The timer lists. */ |
| INIT_LIST_HEAD(&sig->cpu_timers[0]); |
| INIT_LIST_HEAD(&sig->cpu_timers[1]); |
| INIT_LIST_HEAD(&sig->cpu_timers[2]); |
| } |
| |
| static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
| { |
| struct signal_struct *sig; |
| |
| if (clone_flags & CLONE_THREAD) |
| return 0; |
| |
| sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
| tsk->signal = sig; |
| if (!sig) |
| return -ENOMEM; |
| |
| sig->nr_threads = 1; |
| atomic_set(&sig->live, 1); |
| atomic_set(&sig->sigcnt, 1); |
| init_waitqueue_head(&sig->wait_chldexit); |
| sig->curr_target = tsk; |
| init_sigpending(&sig->shared_pending); |
| INIT_LIST_HEAD(&sig->posix_timers); |
| |
| hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| sig->real_timer.function = it_real_fn; |
| |
| task_lock(current->group_leader); |
| memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
| task_unlock(current->group_leader); |
| |
| posix_cpu_timers_init_group(sig); |
| |
| tty_audit_fork(sig); |
| sched_autogroup_fork(sig); |
| |
| #ifdef CONFIG_CGROUPS |
| init_rwsem(&sig->group_rwsem); |
| #endif |
| |
| sig->oom_score_adj = current->signal->oom_score_adj; |
| sig->oom_score_adj_min = current->signal->oom_score_adj_min; |
| |
| sig->has_child_subreaper = current->signal->has_child_subreaper || |
| current->signal->is_child_subreaper; |
| |
| mutex_init(&sig->cred_guard_mutex); |
| |
| return 0; |
| } |
| |
| static void copy_flags(unsigned long clone_flags, struct task_struct *p) |
| { |
| unsigned long new_flags = p->flags; |
| |
| new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); |
| new_flags |= PF_FORKNOEXEC; |
| p->flags = new_flags; |
| } |
| |
| SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
| { |
| current->clear_child_tid = tidptr; |
| |
| return task_pid_vnr(current); |
| } |
| |
| static void rt_mutex_init_task(struct task_struct *p) |
| { |
| raw_spin_lock_init(&p->pi_lock); |
| #ifdef CONFIG_RT_MUTEXES |
| p->pi_waiters = RB_ROOT; |
| p->pi_waiters_leftmost = NULL; |
| p->pi_blocked_on = NULL; |
| p->pi_top_task = NULL; |
| #endif |
| } |
| |
| #ifdef CONFIG_MM_OWNER |
| void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
| { |
| mm->owner = p; |
| } |
| #endif /* CONFIG_MM_OWNER */ |
| |
| /* |
| * Initialize POSIX timer handling for a single task. |
| */ |
| static void posix_cpu_timers_init(struct task_struct *tsk) |
| { |
| tsk->cputime_expires.prof_exp = 0; |
| tsk->cputime_expires.virt_exp = 0; |
| tsk->cputime_expires.sched_exp = 0; |
| INIT_LIST_HEAD(&tsk->cpu_timers[0]); |
| INIT_LIST_HEAD(&tsk->cpu_timers[1]); |
| INIT_LIST_HEAD(&tsk->cpu_timers[2]); |
| } |
| |
| static inline void |
| init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid) |
| { |
| task->pids[type].pid = pid; |
| } |
| |
| /* |
| * This creates a new process as a copy of the old one, |
| * but does not actually start it yet. |
| * |
| * It copies the registers, and all the appropriate |
| * parts of the process environment (as per the clone |
| * flags). The actual kick-off is left to the caller. |
| */ |
| static struct task_struct *copy_process(unsigned long clone_flags, |
| unsigned long stack_start, |
| unsigned long stack_size, |
| int __user *child_tidptr, |
| struct pid *pid, |
| int trace) |
| { |
| int retval; |
| struct task_struct *p; |
| |
| if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
| return ERR_PTR(-EINVAL); |
| |
| if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS)) |
| return ERR_PTR(-EINVAL); |
| |
| /* |
| * Thread groups must share signals as well, and detached threads |
| * can only be started up within the thread group. |
| */ |
| if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
| return ERR_PTR(-EINVAL); |
| |
| /* |
| * Shared signal handlers imply shared VM. By way of the above, |
| * thread groups also imply shared VM. Blocking this case allows |
| * for various simplifications in other code. |
| */ |
| if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
| return ERR_PTR(-EINVAL); |
| |
| /* |
| * Siblings of global init remain as zombies on exit since they are |
| * not reaped by their parent (swapper). To solve this and to avoid |
| * multi-rooted process trees, prevent global and container-inits |
| * from creating siblings. |
| */ |
| if ((clone_flags & CLONE_PARENT) && |
| current->signal->flags & SIGNAL_UNKILLABLE) |
| return ERR_PTR(-EINVAL); |
| |
| /* |
| * If the new process will be in a different pid or user namespace |
| * do not allow it to share a thread group or signal handlers or |
| * parent with the forking task. |
| */ |
| if (clone_flags & CLONE_SIGHAND) { |
| if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) || |
| (task_active_pid_ns(current) != |
| current->nsproxy->pid_ns_for_children)) |
| return ERR_PTR(-EINVAL); |
| } |
| |
| retval = security_task_create(clone_flags); |
| if (retval) |
| goto fork_out; |
| |
| retval = -ENOMEM; |
| p = dup_task_struct(current); |
| if (!p) |
| goto fork_out; |
| |
| ftrace_graph_init_task(p); |
| get_seccomp_filter(p); |
| |
| rt_mutex_init_task(p); |
| |
| #ifdef CONFIG_PROVE_LOCKING |
| DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); |
| DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
| #endif |
| retval = -EAGAIN; |
| if (atomic_read(&p->real_cred->user->processes) >= |
| task_rlimit(p, RLIMIT_NPROC)) { |
| if (p->real_cred->user != INIT_USER && |
| !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) |
| goto bad_fork_free; |
| } |
| current->flags &= ~PF_NPROC_EXCEEDED; |
| |
| retval = copy_creds(p, clone_flags); |
| if (retval < 0) |
| goto bad_fork_free; |
| |
| /* |
| * If multiple threads are within copy_process(), then this check |
| * triggers too late. This doesn't hurt, the check is only there |
| * to stop root fork bombs. |
| */ |
| retval = -EAGAIN; |
| if (nr_threads >= max_threads) |
| goto bad_fork_cleanup_count; |
| |
| if (!try_module_get(task_thread_info(p)->exec_domain->module)) |
| goto bad_fork_cleanup_count; |
| |
| p->did_exec = 0; |
| delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
| copy_flags(clone_flags, p); |
| INIT_LIST_HEAD(&p->children); |
| INIT_LIST_HEAD(&p->sibling); |
| rcu_copy_process(p); |
| p->vfork_done = NULL; |
| spin_lock_init(&p->alloc_lock); |
| |
| init_sigpending(&p->pending); |
| |
| p->utime = p->stime = p->gtime = 0; |
| p->utimescaled = p->stimescaled = 0; |
| #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
| p->prev_cputime.utime = p->prev_cputime.stime = 0; |
| #endif |
| #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN |
| seqlock_init(&p->vtime_seqlock); |
| p->vtime_snap = 0; |
| p->vtime_snap_whence = VTIME_SLEEPING; |
| #endif |
| |
| #if defined(SPLIT_RSS_COUNTING) |
| memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
| #endif |
| |
| p->default_timer_slack_ns = current->timer_slack_ns; |
| |
| task_io_accounting_init(&p->ioac); |
| acct_clear_integrals(p); |
| |
| posix_cpu_timers_init(p); |
| |
| do_posix_clock_monotonic_gettime(&p->start_time); |
| p->real_start_time = p->start_time; |
| monotonic_to_bootbased(&p->real_start_time); |
| p->io_context = NULL; |
| p->audit_context = NULL; |
| if (clone_flags & CLONE_THREAD) |
| threadgroup_change_begin(current); |
| cgroup_fork(p); |
| #ifdef CONFIG_NUMA |
| p->mempolicy = mpol_dup(p->mempolicy); |
| if (IS_ERR(p->mempolicy)) { |
| retval = PTR_ERR(p->mempolicy); |
| p->mempolicy = NULL; |
| goto bad_fork_cleanup_cgroup; |
| } |
| mpol_fix_fork_child_flag(p); |
| #endif |
| #ifdef CONFIG_CPUSETS |
| p->cpuset_mem_spread_rotor = NUMA_NO_NODE; |
| p->cpuset_slab_spread_rotor = NUMA_NO_NODE; |
| seqcount_init(&p->mems_allowed_seq); |
| #endif |
| #ifdef CONFIG_TRACE_IRQFLAGS |
| p->irq_events = 0; |
| p->hardirqs_enabled = 0; |
| p->hardirq_enable_ip = 0; |
| p->hardirq_enable_event = 0; |
| p->hardirq_disable_ip = _THIS_IP_; |
| p->hardirq_disable_event = 0; |
| p->softirqs_enabled = 1; |
| p->softirq_enable_ip = _THIS_IP_; |
| p->softirq_enable_event = 0; |
| p->softirq_disable_ip = 0; |
| p->softirq_disable_event = 0; |
| p->hardirq_context = 0; |
| p->softirq_context = 0; |
| #endif |
| #ifdef CONFIG_LOCKDEP |
| p->lockdep_depth = 0; /* no locks held yet */ |
| p->curr_chain_key = 0; |
| p->lockdep_recursion = 0; |
| #endif |
| |
| #ifdef CONFIG_DEBUG_MUTEXES |
| p->blocked_on = NULL; /* not blocked yet */ |
| #endif |
| #ifdef CONFIG_MEMCG |
| p->memcg_batch.do_batch = 0; |
| p->memcg_batch.memcg = NULL; |
| #endif |
| #ifdef CONFIG_BCACHE |
| p->sequential_io = 0; |
| p->sequential_io_avg = 0; |
| #endif |
| |
| /* Perform scheduler related setup. Assign this task to a CPU. */ |
| retval = sched_fork(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_policy; |
| |
| retval = perf_event_init_task(p); |
| if (retval) |
| goto bad_fork_cleanup_policy; |
| retval = audit_alloc(p); |
| if (retval) |
| goto bad_fork_cleanup_policy; |
| /* copy all the process information */ |
| retval = copy_semundo(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_audit; |
| retval = copy_files(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_semundo; |
| retval = copy_fs(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_files; |
| retval = copy_sighand(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_fs; |
| retval = copy_signal(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_sighand; |
| retval = copy_mm(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_signal; |
| retval = copy_namespaces(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_mm; |
| retval = copy_io(clone_flags, p); |
| if (retval) |
| goto bad_fork_cleanup_namespaces; |
| retval = copy_thread(clone_flags, stack_start, stack_size, p); |
| if (retval) |
| goto bad_fork_cleanup_io; |
| |
| if (pid != &init_struct_pid) { |
| retval = -ENOMEM; |
| pid = alloc_pid(p->nsproxy->pid_ns_for_children); |
| if (!pid) |
| goto bad_fork_cleanup_io; |
| } |
| |
| p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; |
| /* |
| * Clear TID on mm_release()? |
| */ |
| p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; |
| #ifdef CONFIG_BLOCK |
| p->plug = NULL; |
| #endif |
| #ifdef CONFIG_FUTEX |
| p->robust_list = NULL; |
| #ifdef CONFIG_COMPAT |
| p->compat_robust_list = NULL; |
| #endif |
| INIT_LIST_HEAD(&p->pi_state_list); |
| p->pi_state_cache = NULL; |
| #endif |
| /* |
| * sigaltstack should be cleared when sharing the same VM |
| */ |
| if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
| p->sas_ss_sp = p->sas_ss_size = 0; |
| |
| /* |
| * Syscall tracing and stepping should be turned off in the |
| * child regardless of CLONE_PTRACE. |
| */ |
| user_disable_single_step(p); |
| clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); |
| #ifdef TIF_SYSCALL_EMU |
| clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); |
| #endif |
| clear_all_latency_tracing(p); |
| |
| /* ok, now we should be set up.. */ |
| p->pid = pid_nr(pid); |
| if (clone_flags & CLONE_THREAD) { |
| p->exit_signal = -1; |
| p->group_leader = current->group_leader; |
| p->tgid = current->tgid; |
| } else { |
| if (clone_flags & CLONE_PARENT) |
| p->exit_signal = current->group_leader->exit_signal; |
| else |
| p->exit_signal = (clone_flags & CSIGNAL); |
| p->group_leader = p; |
| p->tgid = p->pid; |
| } |
| |
| p->nr_dirtied = 0; |
| p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); |
| p->dirty_paused_when = 0; |
| |
| p->pdeath_signal = 0; |
| INIT_LIST_HEAD(&p->thread_group); |
| p->task_works = NULL; |
| |
| /* |
| * Make it visible to the rest of the system, but dont wake it up yet. |
| * Need tasklist lock for parent etc handling! |
| */ |
| write_lock_irq(&tasklist_lock); |
| |
| /* CLONE_PARENT re-uses the old parent */ |
| if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
| p->real_parent = current->real_parent; |
| p->parent_exec_id = current->parent_exec_id; |
| } else { |
| p->real_parent = current; |
| p->parent_exec_id = current->self_exec_id; |
| } |
| |
| spin_lock(¤t->sighand->siglock); |
| |
| /* |
| * Process group and session signals need to be delivered to just the |
| * parent before the fork or both the parent and the child after the |
| * fork. Restart if a signal comes in before we add the new process to |
| * it's process group. |
| * A fatal signal pending means that current will exit, so the new |
| * thread can't slip out of an OOM kill (or normal SIGKILL). |
| */ |
| recalc_sigpending(); |
| if (signal_pending(current)) { |
| spin_unlock(¤t->sighand->siglock); |
| write_unlock_irq(&tasklist_lock); |
| retval = -ERESTARTNOINTR; |
| goto bad_fork_free_pid; |
| } |
| |
| if (likely(p->pid)) { |
| ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); |
| |
| init_task_pid(p, PIDTYPE_PID, pid); |
| if (thread_group_leader(p)) { |
| init_task_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
| init_task_pid(p, PIDTYPE_SID, task_session(current)); |
| |
| if (is_child_reaper(pid)) { |
| ns_of_pid(pid)->child_reaper = p; |
| p->signal->flags |= SIGNAL_UNKILLABLE; |
| } |
| |
| p->signal->leader_pid = pid; |
| p->signal->tty = tty_kref_get(current->signal->tty); |
| list_add_tail(&p->sibling, &p->real_parent->children); |
| list_add_tail_rcu(&p->tasks, &init_task.tasks); |
| attach_pid(p, PIDTYPE_PGID); |
| attach_pid(p, PIDTYPE_SID); |
| __this_cpu_inc(process_counts); |
| } else { |
| current->signal->nr_threads++; |
| atomic_inc(¤t->signal->live); |
| atomic_inc(¤t->signal->sigcnt); |
| list_add_tail_rcu(&p->thread_group, |
| &p->group_leader->thread_group); |
| } |
| attach_pid(p, PIDTYPE_PID); |
| nr_threads++; |
| } |
| |
| total_forks++; |
| spin_unlock(¤t->sighand->siglock); |
| write_unlock_irq(&tasklist_lock); |
| proc_fork_connector(p); |
| cgroup_post_fork(p); |
| if (clone_flags & CLONE_THREAD) |
| threadgroup_change_end(current); |
| perf_event_fork(p); |
| |
| trace_task_newtask(p, clone_flags); |
| uprobe_copy_process(p, clone_flags); |
| |
| return p; |
| |
| bad_fork_free_pid: |
| if (pid != &init_struct_pid) |
| free_pid(pid); |
| bad_fork_cleanup_io: |
| if (p->io_context) |
| exit_io_context(p); |
| bad_fork_cleanup_namespaces: |
| exit_task_namespaces(p); |
| bad_fork_cleanup_mm: |
| if (p->mm) |
| mmput(p->mm); |
| bad_fork_cleanup_signal: |
| if (!(clone_flags & CLONE_THREAD)) |
| free_signal_struct(p->signal); |
| bad_fork_cleanup_sighand: |
| __cleanup_sighand(p->sighand); |
| bad_fork_cleanup_fs: |
| exit_fs(p); /* blocking */ |
| bad_fork_cleanup_files: |
| exit_files(p); /* blocking */ |
| bad_fork_cleanup_semundo: |
| exit_sem(p); |
| bad_fork_cleanup_audit: |
| audit_free(p); |
| bad_fork_cleanup_policy: |
| perf_event_free_task(p); |
| #ifdef CONFIG_NUMA |
| mpol_put(p->mempolicy); |
| bad_fork_cleanup_cgroup: |
| #endif |
| if (clone_flags & CLONE_THREAD) |
| threadgroup_change_end(current); |
| cgroup_exit(p, 0); |
| delayacct_tsk_free(p); |
| module_put(task_thread_info(p)->exec_domain->module); |
| bad_fork_cleanup_count: |
| atomic_dec(&p->cred->user->processes); |
| exit_creds(p); |
| bad_fork_free: |
| free_task(p); |
| fork_out: |
| return ERR_PTR(retval); |
| } |
| |
| static inline void init_idle_pids(struct pid_link *links) |
| { |
| enum pid_type type; |
| |
| for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
| INIT_HLIST_NODE(&links[type].node); /* not really needed */ |
| links[type].pid = &init_struct_pid; |
| } |
| } |
| |
| struct task_struct *fork_idle(int cpu) |
| { |
| struct task_struct *task; |
| task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0); |
| if (!IS_ERR(task)) { |
| init_idle_pids(task->pids); |
| init_idle(task, cpu); |
| } |
| |
| return task; |
| } |
| |
| /* |
| * Ok, this is the main fork-routine. |
| * |
| * It copies the process, and if successful kick-starts |
| * it and waits for it to finish using the VM if required. |
| */ |
| long do_fork(unsigned long clone_flags, |
| unsigned long stack_start, |
| unsigned long stack_size, |
| int __user *parent_tidptr, |
| int __user *child_tidptr) |
| { |
| struct task_struct *p; |
| int trace = 0; |
| long nr; |
| |
| /* |
| * Determine whether and which event to report to ptracer. When |
| * called from kernel_thread or CLONE_UNTRACED is explicitly |
| * requested, no event is reported; otherwise, report if the event |
| * for the type of forking is enabled. |
| */ |
| if (!(clone_flags & CLONE_UNTRACED)) { |
| if (clone_flags & CLONE_VFORK) |
| trace = PTRACE_EVENT_VFORK; |
| else if ((clone_flags & CSIGNAL) != SIGCHLD) |
| trace = PTRACE_EVENT_CLONE; |
| else |
| trace = PTRACE_EVENT_FORK; |
| |
| if (likely(!ptrace_event_enabled(current, trace))) |
| trace = 0; |
| } |
| |
| p = copy_process(clone_flags, stack_start, stack_size, |
| child_tidptr, NULL, trace); |
| /* |
| * Do this prior waking up the new thread - the thread pointer |
| * might get invalid after that point, if the thread exits quickly. |
| */ |
| if (!IS_ERR(p)) { |
| struct completion vfork; |
| |
| trace_sched_process_fork(current, p); |
| |
| nr = task_pid_vnr(p); |
| |
| if (clone_flags & CLONE_PARENT_SETTID) |
| put_user(nr, parent_tidptr); |
| |
| if (clone_flags & CLONE_VFORK) { |
| p->vfork_done = &vfork; |
| init_completion(&vfork); |
| get_task_struct(p); |
| } |
| |
| wake_up_new_task(p); |
| |
| /* forking complete and child started to run, tell ptracer */ |
| if (unlikely(trace)) |
| ptrace_event(trace, nr); |
| |
| if (clone_flags & CLONE_VFORK) { |
| if (!wait_for_vfork_done(p, &vfork)) |
| ptrace_event(PTRACE_EVENT_VFORK_DONE, nr); |
| } |
| } else { |
| nr = PTR_ERR(p); |
| } |
| return nr; |
| } |
| |
| /* |
| * Create a kernel thread. |
| */ |
| pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) |
| { |
| return do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn, |
| (unsigned long)arg, NULL, NULL); |
| } |
| |
| #ifdef __ARCH_WANT_SYS_FORK |
| SYSCALL_DEFINE0(fork) |
| { |
| #ifdef CONFIG_MMU |
| return do_fork(SIGCHLD, 0, 0, NULL, NULL); |
| #else |
| /* can not support in nommu mode */ |
| return(-EINVAL); |
| #endif |
| } |
| #endif |
| |
| #ifdef __ARCH_WANT_SYS_VFORK |
| SYSCALL_DEFINE0(vfork) |
| { |
| return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0, |
| 0, NULL, NULL); |
| } |
| #endif |
| |
| #ifdef __ARCH_WANT_SYS_CLONE |
| #ifdef CONFIG_CLONE_BACKWARDS |
| SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
| int __user *, parent_tidptr, |
| int, tls_val, |
| int __user *, child_tidptr) |
| #elif defined(CONFIG_CLONE_BACKWARDS2) |
| SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags, |
| int __user *, parent_tidptr, |
| int __user *, child_tidptr, |
| int, tls_val) |
| #elif defined(CONFIG_CLONE_BACKWARDS3) |
| SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp, |
| int, stack_size, |
| int __user *, parent_tidptr, |
| int __user *, child_tidptr, |
| int, tls_val) |
| #else |
| SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, |
| int __user *, parent_tidptr, |
| int __user *, child_tidptr, |
| int, tls_val) |
| #endif |
| { |
| return do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr); |
| } |
| #endif |
| |
| #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
| #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
| #endif |
| |
| static void sighand_ctor(void *data) |
| { |
| struct sighand_struct *sighand = data; |
| |
| spin_lock_init(&sighand->siglock); |
| init_waitqueue_head(&sighand->signalfd_wqh); |
| } |
| |
| void __init proc_caches_init(void) |
| { |
| sighand_cachep = kmem_cache_create("sighand_cache", |
| sizeof(struct sighand_struct), 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| |
| SLAB_NOTRACK, sighand_ctor); |
| signal_cachep = kmem_cache_create("signal_cache", |
| sizeof(struct signal_struct), 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| files_cachep = kmem_cache_create("files_cache", |
| sizeof(struct files_struct), 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| fs_cachep = kmem_cache_create("fs_cache", |
| sizeof(struct fs_struct), 0, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| /* |
| * FIXME! The "sizeof(struct mm_struct)" currently includes the |
| * whole struct cpumask for the OFFSTACK case. We could change |
| * this to *only* allocate as much of it as required by the |
| * maximum number of CPU's we can ever have. The cpumask_allocation |
| * is at the end of the structure, exactly for that reason. |
| */ |
| mm_cachep = kmem_cache_create("mm_struct", |
| sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, |
| SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
| vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); |
| mmap_init(); |
| nsproxy_cache_init(); |
| } |
| |
| /* |
| * Check constraints on flags passed to the unshare system call. |
| */ |
| static int check_unshare_flags(unsigned long unshare_flags) |
| { |
| if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
| CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
| CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET| |
| CLONE_NEWUSER|CLONE_NEWPID)) |
| return -EINVAL; |
| /* |
| * Not implemented, but pretend it works if there is nothing to |
| * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND |
| * needs to unshare vm. |
| */ |
| if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { |
| /* FIXME: get_task_mm() increments ->mm_users */ |
| if (atomic_read(¤t->mm->mm_users) > 1) |
| return -EINVAL; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Unshare the filesystem structure if it is being shared |
| */ |
| static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
| { |
| struct fs_struct *fs = current->fs; |
| |
| if (!(unshare_flags & CLONE_FS) || !fs) |
| return 0; |
| |
| /* don't need lock here; in the worst case we'll do useless copy */ |
| if (fs->users == 1) |
| return 0; |
| |
| *new_fsp = copy_fs_struct(fs); |
| if (!*new_fsp) |
| return -ENOMEM; |
| |
| return 0; |
| } |
| |
| /* |
| * Unshare file descriptor table if it is being shared |
| */ |
| static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) |
| { |
| struct files_struct *fd = current->files; |
| int error = 0; |
| |
| if ((unshare_flags & CLONE_FILES) && |
| (fd && atomic_read(&fd->count) > 1)) { |
| *new_fdp = dup_fd(fd, &error); |
| if (!*new_fdp) |
| return error; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * unshare allows a process to 'unshare' part of the process |
| * context which was originally shared using clone. copy_* |
| * functions used by do_fork() cannot be used here directly |
| * because they modify an inactive task_struct that is being |
| * constructed. Here we are modifying the current, active, |
| * task_struct. |
| */ |
| SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
| { |
| struct fs_struct *fs, *new_fs = NULL; |
| struct files_struct *fd, *new_fd = NULL; |
| struct cred *new_cred = NULL; |
| struct nsproxy *new_nsproxy = NULL; |
| int do_sysvsem = 0; |
| int err; |
| |
| /* |
| * If unsharing a user namespace must also unshare the thread. |
| */ |
| if (unshare_flags & CLONE_NEWUSER) |
| unshare_flags |= CLONE_THREAD | CLONE_FS; |
| /* |
| * If unsharing a thread from a thread group, must also unshare vm. |
| */ |
| if (unshare_flags & CLONE_THREAD) |
| unshare_flags |= CLONE_VM; |
| /* |
| * If unsharing vm, must also unshare signal handlers. |
| */ |
| if (unshare_flags & CLONE_VM) |
| unshare_flags |= CLONE_SIGHAND; |
| /* |
| * If unsharing namespace, must also unshare filesystem information. |
| */ |
| if (unshare_flags & CLONE_NEWNS) |
| unshare_flags |= CLONE_FS; |
| |
| err = check_unshare_flags(unshare_flags); |
| if (err) |
| goto bad_unshare_out; |
| /* |
| * CLONE_NEWIPC must also detach from the undolist: after switching |
| * to a new ipc namespace, the semaphore arrays from the old |
| * namespace are unreachable. |
| */ |
| if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
| do_sysvsem = 1; |
| err = unshare_fs(unshare_flags, &new_fs); |
| if (err) |
| goto bad_unshare_out; |
| err = unshare_fd(unshare_flags, &new_fd); |
| if (err) |
| goto bad_unshare_cleanup_fs; |
| err = unshare_userns(unshare_flags, &new_cred); |
| if (err) |
| goto bad_unshare_cleanup_fd; |
| err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, |
| new_cred, new_fs); |
| if (err) |
| goto bad_unshare_cleanup_cred; |
| |
| if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) { |
| if (do_sysvsem) { |
| /* |
| * CLONE_SYSVSEM is equivalent to sys_exit(). |
| */ |
| exit_sem(current); |
| } |
| |
| if (new_nsproxy) |
| switch_task_namespaces(current, new_nsproxy); |
| |
| task_lock(current); |
| |
| if (new_fs) { |
| fs = current->fs; |
| spin_lock(&fs->lock); |
| current->fs = new_fs; |
| if (--fs->users) |
| new_fs = NULL; |
| else |
| new_fs = fs; |
| spin_unlock(&fs->lock); |
| } |
| |
| if (new_fd) { |
| fd = current->files; |
| current->files = new_fd; |
| new_fd = fd; |
| } |
| |
| task_unlock(current); |
| |
| if (new_cred) { |
| /* Install the new user namespace */ |
| commit_creds(new_cred); |
| new_cred = NULL; |
| } |
| } |
| |
| bad_unshare_cleanup_cred: |
| if (new_cred) |
| put_cred(new_cred); |
| bad_unshare_cleanup_fd: |
| if (new_fd) |
| put_files_struct(new_fd); |
| |
| bad_unshare_cleanup_fs: |
| if (new_fs) |
| free_fs_struct(new_fs); |
| |
| bad_unshare_out: |
| return err; |
| } |
| |
| /* |
| * Helper to unshare the files of the current task. |
| * We don't want to expose copy_files internals to |
| * the exec layer of the kernel. |
| */ |
| |
| int unshare_files(struct files_struct **displaced) |
| { |
| struct task_struct *task = current; |
| struct files_struct *copy = NULL; |
| int error; |
| |
| error = unshare_fd(CLONE_FILES, ©); |
| if (error || !copy) { |
| *displaced = NULL; |
| return error; |
| } |
| *displaced = task->files; |
| task_lock(task); |
| task->files = copy; |
| task_unlock(task); |
| return 0; |
| } |