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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * 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/anon_inodes.h>
- #include <linux/slab.h>
- #include <linux/sched/autogroup.h>
- #include <linux/sched/mm.h>
- #include <linux/sched/coredump.h>
- #include <linux/sched/user.h>
- #include <linux/sched/numa_balancing.h>
- #include <linux/sched/stat.h>
- #include <linux/sched/task.h>
- #include <linux/sched/task_stack.h>
- #include <linux/sched/cputime.h>
- #include <linux/seq_file.h>
- #include <linux/rtmutex.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/kmsan.h>
- #include <linux/binfmts.h>
- #include <linux/mman.h>
- #include <linux/mmu_notifier.h>
- #include <linux/fs.h>
- #include <linux/mm.h>
- #include <linux/mm_inline.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/userfaultfd_k.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/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 <linux/compiler.h>
- #include <linux/sysctl.h>
- #include <linux/kcov.h>
- #include <linux/livepatch.h>
- #include <linux/thread_info.h>
- #include <linux/stackleak.h>
- #include <linux/kasan.h>
- #include <linux/scs.h>
- #include <linux/io_uring.h>
- #include <linux/bpf.h>
- #include <linux/cpufreq_times.h>
- #include <asm/pgalloc.h>
- #include <linux/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>
- #undef CREATE_TRACE_POINTS
- #include <trace/hooks/sched.h>
- #ifdef CONFIG_KDP_CRED
- #include <linux/kdp.h>
- #endif
- /*
- * Minimum number of threads to boot the kernel
- */
- #define MIN_THREADS 20
- /*
- * Maximum number of threads
- */
- #define MAX_THREADS FUTEX_TID_MASK
- EXPORT_TRACEPOINT_SYMBOL_GPL(task_newtask);
- EXPORT_TRACEPOINT_SYMBOL_GPL(task_rename);
- /*
- * 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.. */
- static int max_threads; /* tunable limit on nr_threads */
- #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
- static const char * const resident_page_types[] = {
- NAMED_ARRAY_INDEX(MM_FILEPAGES),
- NAMED_ARRAY_INDEX(MM_ANONPAGES),
- NAMED_ARRAY_INDEX(MM_SWAPENTS),
- NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
- };
- DEFINE_PER_CPU(unsigned long, process_counts) = 0;
- __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
- EXPORT_SYMBOL_GPL(tasklist_lock);
- #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
- #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
- /*
- * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
- * kmemcache based allocator.
- */
- # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
- # ifdef CONFIG_VMAP_STACK
- /*
- * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
- * flush. Try to minimize the number of calls by caching stacks.
- */
- #define NR_CACHED_STACKS 2
- static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
- struct vm_stack {
- struct rcu_head rcu;
- struct vm_struct *stack_vm_area;
- };
- static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
- {
- unsigned int i;
- for (i = 0; i < NR_CACHED_STACKS; i++) {
- if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
- continue;
- return true;
- }
- return false;
- }
- static void thread_stack_free_rcu(struct rcu_head *rh)
- {
- struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
- if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
- return;
- vfree(vm_stack);
- }
- static void thread_stack_delayed_free(struct task_struct *tsk)
- {
- struct vm_stack *vm_stack = tsk->stack;
- vm_stack->stack_vm_area = tsk->stack_vm_area;
- call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
- }
- static int free_vm_stack_cache(unsigned int cpu)
- {
- struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
- int i;
- for (i = 0; i < NR_CACHED_STACKS; i++) {
- struct vm_struct *vm_stack = cached_vm_stacks[i];
- if (!vm_stack)
- continue;
- vfree(vm_stack->addr);
- cached_vm_stacks[i] = NULL;
- }
- return 0;
- }
- static int memcg_charge_kernel_stack(struct vm_struct *vm)
- {
- int i;
- int ret;
- BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
- BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
- ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
- if (ret)
- goto err;
- }
- return 0;
- err:
- /*
- * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
- * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
- * ignore this page.
- */
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
- memcg_kmem_uncharge_page(vm->pages[i], 0);
- return ret;
- }
- static int alloc_thread_stack_node(struct task_struct *tsk, int node)
- {
- struct vm_struct *vm;
- void *stack;
- int i;
- for (i = 0; i < NR_CACHED_STACKS; i++) {
- struct vm_struct *s;
- s = this_cpu_xchg(cached_stacks[i], NULL);
- if (!s)
- continue;
- /* Reset stack metadata. */
- kasan_unpoison_range(s->addr, THREAD_SIZE);
- stack = kasan_reset_tag(s->addr);
- /* Clear stale pointers from reused stack. */
- memset(stack, 0, THREAD_SIZE);
- if (memcg_charge_kernel_stack(s)) {
- vfree(s->addr);
- return -ENOMEM;
- }
- tsk->stack_vm_area = s;
- tsk->stack = stack;
- return 0;
- }
- /*
- * Allocated stacks are cached and later reused by new threads,
- * so memcg accounting is performed manually on assigning/releasing
- * stacks to tasks. Drop __GFP_ACCOUNT.
- */
- stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
- VMALLOC_START, VMALLOC_END,
- THREADINFO_GFP & ~__GFP_ACCOUNT,
- PAGE_KERNEL,
- 0, node, __builtin_return_address(0));
- if (!stack)
- return -ENOMEM;
- vm = find_vm_area(stack);
- if (memcg_charge_kernel_stack(vm)) {
- vfree(stack);
- return -ENOMEM;
- }
- /*
- * We can't call find_vm_area() in interrupt context, and
- * free_thread_stack() can be called in interrupt context,
- * so cache the vm_struct.
- */
- tsk->stack_vm_area = vm;
- stack = kasan_reset_tag(stack);
- tsk->stack = stack;
- return 0;
- }
- static void free_thread_stack(struct task_struct *tsk)
- {
- if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
- thread_stack_delayed_free(tsk);
- tsk->stack = NULL;
- tsk->stack_vm_area = NULL;
- }
- # else /* !CONFIG_VMAP_STACK */
- static void thread_stack_free_rcu(struct rcu_head *rh)
- {
- __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
- }
- static void thread_stack_delayed_free(struct task_struct *tsk)
- {
- struct rcu_head *rh = tsk->stack;
- call_rcu(rh, thread_stack_free_rcu);
- }
- static int alloc_thread_stack_node(struct task_struct *tsk, int node)
- {
- struct page *page = alloc_pages_node(node, THREADINFO_GFP,
- THREAD_SIZE_ORDER);
- if (likely(page)) {
- tsk->stack = kasan_reset_tag(page_address(page));
- return 0;
- }
- return -ENOMEM;
- }
- static void free_thread_stack(struct task_struct *tsk)
- {
- thread_stack_delayed_free(tsk);
- tsk->stack = NULL;
- }
- # endif /* CONFIG_VMAP_STACK */
- # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
- static struct kmem_cache *thread_stack_cache;
- static void thread_stack_free_rcu(struct rcu_head *rh)
- {
- kmem_cache_free(thread_stack_cache, rh);
- }
- static void thread_stack_delayed_free(struct task_struct *tsk)
- {
- struct rcu_head *rh = tsk->stack;
- call_rcu(rh, thread_stack_free_rcu);
- }
- static int alloc_thread_stack_node(struct task_struct *tsk, int node)
- {
- unsigned long *stack;
- stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
- stack = kasan_reset_tag(stack);
- tsk->stack = stack;
- return stack ? 0 : -ENOMEM;
- }
- static void free_thread_stack(struct task_struct *tsk)
- {
- thread_stack_delayed_free(tsk);
- tsk->stack = NULL;
- }
- void thread_stack_cache_init(void)
- {
- thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
- THREAD_SIZE, THREAD_SIZE, 0, 0,
- THREAD_SIZE, NULL);
- BUG_ON(thread_stack_cache == NULL);
- }
- # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
- #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
- static int alloc_thread_stack_node(struct task_struct *tsk, int node)
- {
- unsigned long *stack;
- stack = arch_alloc_thread_stack_node(tsk, node);
- tsk->stack = stack;
- return stack ? 0 : -ENOMEM;
- }
- static void free_thread_stack(struct task_struct *tsk)
- {
- arch_free_thread_stack(tsk);
- tsk->stack = NULL;
- }
- #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
- /* 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 */
- static struct kmem_cache *vm_area_cachep;
- /* SLAB cache for mm_struct structures (tsk->mm) */
- static struct kmem_cache *mm_cachep;
- #ifdef CONFIG_PER_VMA_LOCK
- /* SLAB cache for vm_area_struct.lock */
- static struct kmem_cache *vma_lock_cachep;
- static bool vma_lock_alloc(struct vm_area_struct *vma)
- {
- vma->vm_lock = kmem_cache_alloc(vma_lock_cachep, GFP_KERNEL);
- if (!vma->vm_lock)
- return false;
- init_rwsem(&vma->vm_lock->lock);
- vma->vm_lock_seq = -1;
- return true;
- }
- static inline void vma_lock_free(struct vm_area_struct *vma)
- {
- kmem_cache_free(vma_lock_cachep, vma->vm_lock);
- }
- #else /* CONFIG_PER_VMA_LOCK */
- static inline bool vma_lock_alloc(struct vm_area_struct *vma) { return true; }
- static inline void vma_lock_free(struct vm_area_struct *vma) {}
- #endif /* CONFIG_PER_VMA_LOCK */
- struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
- {
- struct vm_area_struct *vma;
- vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
- if (!vma)
- return NULL;
- vma_init(vma, mm);
- if (!vma_lock_alloc(vma)) {
- kmem_cache_free(vm_area_cachep, vma);
- return NULL;
- }
- return vma;
- }
- struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
- {
- struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
- if (!new)
- return NULL;
- ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
- ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
- /*
- * orig->shared.rb may be modified concurrently, but the clone
- * will be reinitialized.
- */
- data_race(memcpy(new, orig, sizeof(*new)));
- if (!vma_lock_alloc(new)) {
- kmem_cache_free(vm_area_cachep, new);
- return NULL;
- }
- INIT_LIST_HEAD(&new->anon_vma_chain);
- dup_anon_vma_name(orig, new);
- return new;
- }
- void __vm_area_free(struct vm_area_struct *vma)
- {
- free_anon_vma_name(vma);
- vma_lock_free(vma);
- kmem_cache_free(vm_area_cachep, vma);
- }
- #ifdef CONFIG_PER_VMA_LOCK
- static void vm_area_free_rcu_cb(struct rcu_head *head)
- {
- struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
- vm_rcu);
- /* The vma should not be locked while being destroyed. */
- VM_BUG_ON_VMA(rwsem_is_locked(&vma->vm_lock->lock), vma);
- __vm_area_free(vma);
- }
- #endif
- void vm_area_free(struct vm_area_struct *vma)
- {
- #ifdef CONFIG_PER_VMA_LOCK
- call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
- #else
- __vm_area_free(vma);
- #endif
- }
- static void account_kernel_stack(struct task_struct *tsk, int account)
- {
- if (IS_ENABLED(CONFIG_VMAP_STACK)) {
- struct vm_struct *vm = task_stack_vm_area(tsk);
- int i;
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
- mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
- account * (PAGE_SIZE / 1024));
- } else {
- void *stack = task_stack_page(tsk);
- /* All stack pages are in the same node. */
- mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
- account * (THREAD_SIZE / 1024));
- }
- }
- void exit_task_stack_account(struct task_struct *tsk)
- {
- account_kernel_stack(tsk, -1);
- if (IS_ENABLED(CONFIG_VMAP_STACK)) {
- struct vm_struct *vm;
- int i;
- vm = task_stack_vm_area(tsk);
- for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
- memcg_kmem_uncharge_page(vm->pages[i], 0);
- }
- }
- static void release_task_stack(struct task_struct *tsk)
- {
- if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
- return; /* Better to leak the stack than to free prematurely */
- free_thread_stack(tsk);
- }
- #ifdef CONFIG_THREAD_INFO_IN_TASK
- void put_task_stack(struct task_struct *tsk)
- {
- if (refcount_dec_and_test(&tsk->stack_refcount))
- release_task_stack(tsk);
- }
- #endif
- void free_task(struct task_struct *tsk)
- {
- #ifdef CONFIG_SECCOMP
- WARN_ON_ONCE(tsk->seccomp.filter);
- #endif
- cpufreq_task_times_exit(tsk);
- release_user_cpus_ptr(tsk);
- scs_release(tsk);
- trace_android_vh_free_task(tsk);
- #ifndef CONFIG_THREAD_INFO_IN_TASK
- /*
- * The task is finally done with both the stack and thread_info,
- * so free both.
- */
- release_task_stack(tsk);
- #else
- /*
- * If the task had a separate stack allocation, it should be gone
- * by now.
- */
- WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
- #endif
- rt_mutex_debug_task_free(tsk);
- ftrace_graph_exit_task(tsk);
- arch_release_task_struct(tsk);
- if (tsk->flags & PF_KTHREAD)
- free_kthread_struct(tsk);
- bpf_task_storage_free(tsk);
- free_task_struct(tsk);
- }
- EXPORT_SYMBOL(free_task);
- static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
- {
- struct file *exe_file;
- exe_file = get_mm_exe_file(oldmm);
- RCU_INIT_POINTER(mm->exe_file, exe_file);
- /*
- * We depend on the oldmm having properly denied write access to the
- * exe_file already.
- */
- if (exe_file && deny_write_access(exe_file))
- pr_warn_once("deny_write_access() failed in %s\n", __func__);
- }
- #ifdef CONFIG_MMU
- static __latent_entropy int dup_mmap(struct mm_struct *mm,
- struct mm_struct *oldmm)
- {
- struct vm_area_struct *mpnt, *tmp;
- int retval;
- unsigned long charge = 0;
- LIST_HEAD(uf);
- MA_STATE(mas, &mm->mm_mt, 0, 0);
- uprobe_start_dup_mmap();
- if (mmap_write_lock_killable(oldmm)) {
- retval = -EINTR;
- goto fail_uprobe_end;
- }
- flush_cache_dup_mm(oldmm);
- uprobe_dup_mmap(oldmm, mm);
- /*
- * Not linked in yet - no deadlock potential:
- */
- mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
- /* No ordering required: file already has been exposed. */
- dup_mm_exe_file(mm, oldmm);
- mm->total_vm = oldmm->total_vm;
- mm->data_vm = oldmm->data_vm;
- mm->exec_vm = oldmm->exec_vm;
- mm->stack_vm = oldmm->stack_vm;
- retval = ksm_fork(mm, oldmm);
- if (retval)
- goto out;
- khugepaged_fork(mm, oldmm);
- /* Use __mt_dup() to efficiently build an identical maple tree. */
- retval = __mt_dup(&oldmm->mm_mt, &mm->mm_mt, GFP_KERNEL);
- if (unlikely(retval))
- goto out;
- mt_clear_in_rcu(mas.tree);
- mas_for_each(&mas, mpnt, ULONG_MAX) {
- struct file *file;
- vma_start_write(mpnt);
- if (mpnt->vm_flags & VM_DONTCOPY) {
- __mas_set_range(&mas, mpnt->vm_start, mpnt->vm_end - 1);
- mas_store_gfp(&mas, NULL, GFP_KERNEL);
- if (unlikely(mas_is_err(&mas))) {
- retval = -ENOMEM;
- goto loop_out;
- }
- vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
- continue;
- }
- charge = 0;
- /*
- * Don't duplicate many vmas if we've been oom-killed (for
- * example)
- */
- if (fatal_signal_pending(current)) {
- retval = -EINTR;
- goto loop_out;
- }
- 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 = vm_area_dup(mpnt);
- if (!tmp)
- goto fail_nomem;
- retval = vma_dup_policy(mpnt, tmp);
- if (retval)
- goto fail_nomem_policy;
- tmp->vm_mm = mm;
- retval = dup_userfaultfd(tmp, &uf);
- if (retval)
- goto fail_nomem_anon_vma_fork;
- if (tmp->vm_flags & VM_WIPEONFORK) {
- /*
- * VM_WIPEONFORK gets a clean slate in the child.
- * Don't prepare anon_vma until fault since we don't
- * copy page for current vma.
- */
- tmp->anon_vma = NULL;
- } else if (anon_vma_fork(tmp, mpnt))
- goto fail_nomem_anon_vma_fork;
- vm_flags_clear(tmp, VM_LOCKED_MASK);
- file = tmp->vm_file;
- if (file) {
- struct address_space *mapping = file->f_mapping;
- get_file(file);
- i_mmap_lock_write(mapping);
- if (tmp->vm_flags & VM_SHARED)
- mapping_allow_writable(mapping);
- flush_dcache_mmap_lock(mapping);
- /* insert tmp into the share list, just after mpnt */
- vma_interval_tree_insert_after(tmp, mpnt,
- &mapping->i_mmap);
- flush_dcache_mmap_unlock(mapping);
- i_mmap_unlock_write(mapping);
- }
- /*
- * Copy/update hugetlb private vma information.
- */
- if (is_vm_hugetlb_page(tmp))
- hugetlb_dup_vma_private(tmp);
- /*
- * Link the vma into the MT. After using __mt_dup(), memory
- * allocation is not necessary here, so it cannot fail.
- */
- mas.index = tmp->vm_start;
- mas.last = tmp->vm_end - 1;
- mas_store(&mas, tmp);
- mm->map_count++;
- if (!(tmp->vm_flags & VM_WIPEONFORK))
- retval = copy_page_range(tmp, mpnt);
- if (tmp->vm_ops && tmp->vm_ops->open)
- tmp->vm_ops->open(tmp);
- if (retval) {
- mpnt = mas_find(&mas, ULONG_MAX);
- goto loop_out;
- }
- }
- /* a new mm has just been created */
- retval = arch_dup_mmap(oldmm, mm);
- loop_out:
- mas_destroy(&mas);
- if (!retval) {
- mt_set_in_rcu(mas.tree);
- } else if (mpnt) {
- /*
- * The entire maple tree has already been duplicated. If the
- * mmap duplication fails, mark the failure point with
- * XA_ZERO_ENTRY. In exit_mmap(), if this marker is encountered,
- * stop releasing VMAs that have not been duplicated after this
- * point.
- */
- mas_set_range(&mas, mpnt->vm_start, mpnt->vm_end - 1);
- mas_store(&mas, XA_ZERO_ENTRY);
- }
- out:
- mmap_write_unlock(mm);
- flush_tlb_mm(oldmm);
- mmap_write_unlock(oldmm);
- dup_userfaultfd_complete(&uf);
- fail_uprobe_end:
- uprobe_end_dup_mmap();
- return retval;
- fail_nomem_anon_vma_fork:
- mpol_put(vma_policy(tmp));
- fail_nomem_policy:
- vm_area_free(tmp);
- fail_nomem:
- retval = -ENOMEM;
- vm_unacct_memory(charge);
- goto loop_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
- static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
- {
- mmap_write_lock(oldmm);
- dup_mm_exe_file(mm, oldmm);
- mmap_write_unlock(oldmm);
- return 0;
- }
- #define mm_alloc_pgd(mm) (0)
- #define mm_free_pgd(mm)
- #endif /* CONFIG_MMU */
- static void check_mm(struct mm_struct *mm)
- {
- int i;
- BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
- "Please make sure 'struct resident_page_types[]' is updated as well");
- for (i = 0; i < NR_MM_COUNTERS; i++) {
- long x = atomic_long_read(&mm->rss_stat.count[i]);
- if (unlikely(x))
- pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
- mm, resident_page_types[i], x);
- }
- if (mm_pgtables_bytes(mm))
- pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
- mm_pgtables_bytes(mm));
- #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
- VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
- #endif
- }
- #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
- #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
- /*
- * 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);
- WARN_ON_ONCE(mm == current->mm);
- WARN_ON_ONCE(mm == current->active_mm);
- mm_free_pgd(mm);
- destroy_context(mm);
- mmu_notifier_subscriptions_destroy(mm);
- check_mm(mm);
- put_user_ns(mm->user_ns);
- mm_pasid_drop(mm);
- free_mm(mm);
- }
- EXPORT_SYMBOL_GPL(__mmdrop);
- static void mmdrop_async_fn(struct work_struct *work)
- {
- struct mm_struct *mm;
- mm = container_of(work, struct mm_struct, async_put_work);
- __mmdrop(mm);
- }
- static void mmdrop_async(struct mm_struct *mm)
- {
- if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
- INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
- schedule_work(&mm->async_put_work);
- }
- }
- static inline void free_signal_struct(struct signal_struct *sig)
- {
- taskstats_tgid_free(sig);
- sched_autogroup_exit(sig);
- /*
- * __mmdrop is not safe to call from softirq context on x86 due to
- * pgd_dtor so postpone it to the async context
- */
- if (sig->oom_mm)
- mmdrop_async(sig->oom_mm);
- kmem_cache_free(signal_cachep, sig);
- }
- static inline void put_signal_struct(struct signal_struct *sig)
- {
- if (refcount_dec_and_test(&sig->sigcnt))
- free_signal_struct(sig);
- }
- void __put_task_struct(struct task_struct *tsk)
- {
- WARN_ON(!tsk->exit_state);
- WARN_ON(refcount_read(&tsk->usage));
- WARN_ON(tsk == current);
- io_uring_free(tsk);
- cgroup_free(tsk);
- task_numa_free(tsk, true);
- security_task_free(tsk);
- exit_creds(tsk);
- delayacct_tsk_free(tsk);
- put_signal_struct(tsk->signal);
- sched_core_free(tsk);
- free_task(tsk);
- }
- EXPORT_SYMBOL_GPL(__put_task_struct);
- void __put_task_struct_rcu_cb(struct rcu_head *rhp)
- {
- struct task_struct *task = container_of(rhp, struct task_struct, rcu);
- __put_task_struct(task);
- }
- EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
- void __init __weak arch_task_cache_init(void) { }
- /*
- * set_max_threads
- */
- static void set_max_threads(unsigned int max_threads_suggested)
- {
- u64 threads;
- unsigned long nr_pages = totalram_pages();
- /*
- * The number of threads shall be limited such that the thread
- * structures may only consume a small part of the available memory.
- */
- if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
- threads = MAX_THREADS;
- else
- threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
- (u64) THREAD_SIZE * 8UL);
- if (threads > max_threads_suggested)
- threads = max_threads_suggested;
- max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
- }
- #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
- /* Initialized by the architecture: */
- int arch_task_struct_size __read_mostly;
- #endif
- #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
- static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
- {
- /* Fetch thread_struct whitelist for the architecture. */
- arch_thread_struct_whitelist(offset, size);
- /*
- * Handle zero-sized whitelist or empty thread_struct, otherwise
- * adjust offset to position of thread_struct in task_struct.
- */
- if (unlikely(*size == 0))
- *offset = 0;
- else
- *offset += offsetof(struct task_struct, thread);
- }
- #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
- void __init fork_init(void)
- {
- int i;
- #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
- #ifndef ARCH_MIN_TASKALIGN
- #define ARCH_MIN_TASKALIGN 0
- #endif
- int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
- unsigned long useroffset, usersize;
- /* create a slab on which task_structs can be allocated */
- task_struct_whitelist(&useroffset, &usersize);
- task_struct_cachep = kmem_cache_create_usercopy("task_struct",
- arch_task_struct_size, align,
- SLAB_PANIC|SLAB_ACCOUNT,
- useroffset, usersize, NULL);
- #endif
- /* do the arch specific task caches init */
- arch_task_cache_init();
- set_max_threads(MAX_THREADS);
- 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];
- for (i = 0; i < UCOUNT_COUNTS; i++)
- init_user_ns.ucount_max[i] = max_threads/2;
- set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
- set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
- set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
- set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
- #ifdef CONFIG_VMAP_STACK
- cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
- NULL, free_vm_stack_cache);
- #endif
- scs_init();
- lockdep_init_task(&init_task);
- uprobes_init();
- }
- int __weak arch_dup_task_struct(struct task_struct *dst,
- struct task_struct *src)
- {
- *dst = *src;
- return 0;
- }
- void set_task_stack_end_magic(struct task_struct *tsk)
- {
- unsigned long *stackend;
- stackend = end_of_stack(tsk);
- *stackend = STACK_END_MAGIC; /* for overflow detection */
- }
- static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
- {
- struct task_struct *tsk;
- int err;
- if (node == NUMA_NO_NODE)
- node = tsk_fork_get_node(orig);
- tsk = alloc_task_struct_node(node);
- if (!tsk)
- return NULL;
- err = arch_dup_task_struct(tsk, orig);
- if (err)
- goto free_tsk;
- err = alloc_thread_stack_node(tsk, node);
- if (err)
- goto free_tsk;
- #ifdef CONFIG_THREAD_INFO_IN_TASK
- refcount_set(&tsk->stack_refcount, 1);
- #endif
- account_kernel_stack(tsk, 1);
- err = scs_prepare(tsk, node);
- if (err)
- goto free_stack;
- #ifdef CONFIG_SECCOMP
- /*
- * We must handle setting up seccomp filters once we're under
- * the sighand lock in case orig has changed between now and
- * then. Until then, filter must be NULL to avoid messing up
- * the usage counts on the error path calling free_task.
- */
- tsk->seccomp.filter = NULL;
- #endif
- setup_thread_stack(tsk, orig);
- clear_user_return_notifier(tsk);
- clear_tsk_need_resched(tsk);
- set_task_stack_end_magic(tsk);
- clear_syscall_work_syscall_user_dispatch(tsk);
- #ifdef CONFIG_STACKPROTECTOR
- tsk->stack_canary = get_random_canary();
- #endif
- if (orig->cpus_ptr == &orig->cpus_mask)
- tsk->cpus_ptr = &tsk->cpus_mask;
- dup_user_cpus_ptr(tsk, orig, node);
- /*
- * One for the user space visible state that goes away when reaped.
- * One for the scheduler.
- */
- refcount_set(&tsk->rcu_users, 2);
- /* One for the rcu users */
- refcount_set(&tsk->usage, 1);
- #ifdef CONFIG_BLK_DEV_IO_TRACE
- tsk->btrace_seq = 0;
- #endif
- tsk->splice_pipe = NULL;
- tsk->task_frag.page = NULL;
- tsk->wake_q.next = NULL;
- tsk->worker_private = NULL;
- kcov_task_init(tsk);
- kmsan_task_create(tsk);
- kmap_local_fork(tsk);
- #ifdef CONFIG_FAULT_INJECTION
- tsk->fail_nth = 0;
- #endif
- #ifdef CONFIG_BLK_CGROUP
- tsk->throttle_queue = NULL;
- tsk->use_memdelay = 0;
- #endif
- #ifdef CONFIG_IOMMU_SVA
- tsk->pasid_activated = 0;
- #endif
- #ifdef CONFIG_MEMCG
- tsk->active_memcg = NULL;
- #endif
- #ifdef CONFIG_CPU_SUP_INTEL
- tsk->reported_split_lock = 0;
- #endif
- android_init_vendor_data(tsk, 1);
- android_init_oem_data(tsk, 1);
- trace_android_vh_dup_task_struct(tsk, orig);
- return tsk;
- free_stack:
- exit_task_stack_account(tsk);
- free_thread_stack(tsk);
- free_tsk:
- free_task_struct(tsk);
- return NULL;
- }
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
- 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 __always_inline void mm_clear_owner(struct mm_struct *mm,
- struct task_struct *p)
- {
- #ifdef CONFIG_MEMCG
- if (mm->owner == p)
- WRITE_ONCE(mm->owner, NULL);
- #endif
- }
- static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
- {
- #ifdef CONFIG_MEMCG
- mm->owner = p;
- #endif
- }
- static void mm_init_uprobes_state(struct mm_struct *mm)
- {
- #ifdef CONFIG_UPROBES
- mm->uprobes_state.xol_area = NULL;
- #endif
- }
- static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
- struct user_namespace *user_ns)
- {
- mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
- mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
- atomic_set(&mm->mm_users, 1);
- atomic_set(&mm->mm_count, 1);
- seqcount_init(&mm->write_protect_seq);
- mmap_init_lock(mm);
- INIT_LIST_HEAD(&mm->mmlist);
- #ifdef CONFIG_PER_VMA_LOCK
- mm->mm_lock_seq = 0;
- #endif
- mm_pgtables_bytes_init(mm);
- mm->map_count = 0;
- mm->locked_vm = 0;
- atomic64_set(&mm->pinned_vm, 0);
- memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
- spin_lock_init(&mm->page_table_lock);
- spin_lock_init(&mm->arg_lock);
- mm_init_cpumask(mm);
- mm_init_aio(mm);
- mm_init_owner(mm, p);
- mm_pasid_init(mm);
- RCU_INIT_POINTER(mm->exe_file, NULL);
- mmu_notifier_subscriptions_init(mm);
- init_tlb_flush_pending(mm);
- #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
- mm->pmd_huge_pte = NULL;
- #endif
- mm_init_uprobes_state(mm);
- hugetlb_count_init(mm);
- if (current->mm) {
- mm->flags = current->mm->flags & MMF_INIT_MASK;
- mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
- } else {
- mm->flags = default_dump_filter;
- mm->def_flags = 0;
- }
- if (mm_alloc_pgd(mm))
- goto fail_nopgd;
- if (init_new_context(p, mm))
- goto fail_nocontext;
- mm->user_ns = get_user_ns(user_ns);
- lru_gen_init_mm(mm);
- return mm;
- fail_nocontext:
- mm_free_pgd(mm);
- fail_nopgd:
- free_mm(mm);
- return NULL;
- }
- /*
- * 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));
- return mm_init(mm, current, current_user_ns());
- }
- static inline void __mmput(struct mm_struct *mm)
- {
- VM_BUG_ON(atomic_read(&mm->mm_users));
- uprobe_clear_state(mm);
- exit_aio(mm);
- ksm_exit(mm);
- khugepaged_exit(mm); /* must run before exit_mmap */
- exit_mmap(mm);
- mm_put_huge_zero_page(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);
- lru_gen_del_mm(mm);
- mmdrop(mm);
- }
- /*
- * 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)) {
- trace_android_vh_mmput(mm);
- __mmput(mm);
- }
- }
- EXPORT_SYMBOL_GPL(mmput);
- #ifdef CONFIG_MMU
- static void mmput_async_fn(struct work_struct *work)
- {
- struct mm_struct *mm = container_of(work, struct mm_struct,
- async_put_work);
- __mmput(mm);
- }
- void mmput_async(struct mm_struct *mm)
- {
- if (atomic_dec_and_test(&mm->mm_users)) {
- INIT_WORK(&mm->async_put_work, mmput_async_fn);
- schedule_work(&mm->async_put_work);
- }
- }
- EXPORT_SYMBOL_GPL(mmput_async);
- #endif
- /**
- * set_mm_exe_file - change a reference to the mm's executable file
- *
- * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
- *
- * Main users are mmput() and sys_execve(). Callers prevent concurrent
- * invocations: in mmput() nobody alive left, in execve task is single
- * threaded.
- *
- * Can only fail if new_exe_file != NULL.
- */
- int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
- {
- struct file *old_exe_file;
- /*
- * It is safe to dereference the exe_file without RCU as
- * this function is only called if nobody else can access
- * this mm -- see comment above for justification.
- */
- old_exe_file = rcu_dereference_raw(mm->exe_file);
- if (new_exe_file) {
- /*
- * We expect the caller (i.e., sys_execve) to already denied
- * write access, so this is unlikely to fail.
- */
- if (unlikely(deny_write_access(new_exe_file)))
- return -EACCES;
- get_file(new_exe_file);
- }
- rcu_assign_pointer(mm->exe_file, new_exe_file);
- if (old_exe_file) {
- allow_write_access(old_exe_file);
- fput(old_exe_file);
- }
- return 0;
- }
- /**
- * replace_mm_exe_file - replace a reference to the mm's executable file
- *
- * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
- * dealing with concurrent invocation and without grabbing the mmap lock in
- * write mode.
- *
- * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
- */
- int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
- {
- struct vm_area_struct *vma;
- struct file *old_exe_file;
- int ret = 0;
- /* Forbid mm->exe_file change if old file still mapped. */
- old_exe_file = get_mm_exe_file(mm);
- if (old_exe_file) {
- VMA_ITERATOR(vmi, mm, 0);
- mmap_read_lock(mm);
- for_each_vma(vmi, vma) {
- if (!vma->vm_file)
- continue;
- if (path_equal(&vma->vm_file->f_path,
- &old_exe_file->f_path)) {
- ret = -EBUSY;
- break;
- }
- }
- mmap_read_unlock(mm);
- fput(old_exe_file);
- if (ret)
- return ret;
- }
- /* set the new file, lockless */
- ret = deny_write_access(new_exe_file);
- if (ret)
- return -EACCES;
- get_file(new_exe_file);
- old_exe_file = xchg(&mm->exe_file, new_exe_file);
- if (old_exe_file) {
- /*
- * Don't race with dup_mmap() getting the file and disallowing
- * write access while someone might open the file writable.
- */
- mmap_read_lock(mm);
- allow_write_access(old_exe_file);
- fput(old_exe_file);
- mmap_read_unlock(mm);
- }
- return 0;
- }
- /**
- * get_mm_exe_file - acquire a reference to the mm's executable file
- *
- * Returns %NULL if mm has no associated executable file.
- * User must release file via fput().
- */
- struct file *get_mm_exe_file(struct mm_struct *mm)
- {
- struct file *exe_file;
- rcu_read_lock();
- exe_file = rcu_dereference(mm->exe_file);
- if (exe_file && !get_file_rcu(exe_file))
- exe_file = NULL;
- rcu_read_unlock();
- return exe_file;
- }
- /**
- * get_task_exe_file - acquire a reference to the task's executable file
- *
- * Returns %NULL if task's mm (if any) has no associated executable file or
- * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
- * User must release file via fput().
- */
- struct file *get_task_exe_file(struct task_struct *task)
- {
- struct file *exe_file = NULL;
- struct mm_struct *mm;
- task_lock(task);
- mm = task->mm;
- if (mm) {
- if (!(task->flags & PF_KTHREAD))
- exe_file = get_mm_exe_file(mm);
- }
- task_unlock(task);
- return exe_file;
- }
- /**
- * 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
- mmget(mm);
- }
- 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 = down_read_killable(&task->signal->exec_update_lock);
- 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);
- }
- up_read(&task->signal->exec_update_lock);
- 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)
- {
- unsigned int state = TASK_UNINTERRUPTIBLE|TASK_KILLABLE|TASK_FREEZABLE;
- int killed;
- cgroup_enter_frozen();
- killed = wait_for_completion_state(vfork, state);
- cgroup_leave_frozen(false);
- 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
- */
- static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
- {
- uprobe_free_utask(tsk);
- /* Get rid of any cached register state */
- deactivate_mm(tsk, mm);
- /*
- * Signal userspace if we're not exiting with a core dump
- * because we want to leave the value intact for debugging
- * purposes.
- */
- if (tsk->clear_child_tid) {
- if (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);
- do_futex(tsk->clear_child_tid, FUTEX_WAKE,
- 1, NULL, NULL, 0, 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);
- }
- void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
- {
- futex_exit_release(tsk);
- mm_release(tsk, mm);
- }
- void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
- {
- futex_exec_release(tsk);
- mm_release(tsk, mm);
- }
- /**
- * dup_mm() - duplicates an existing mm structure
- * @tsk: the task_struct with which the new mm will be associated.
- * @oldmm: the mm to duplicate.
- *
- * Allocates a new mm structure and duplicates the provided @oldmm structure
- * content into it.
- *
- * Return: the duplicated mm or NULL on failure.
- */
- static struct mm_struct *dup_mm(struct task_struct *tsk,
- struct mm_struct *oldmm)
- {
- struct mm_struct *mm;
- int err;
- mm = allocate_mm();
- if (!mm)
- goto fail_nomem;
- memcpy(mm, oldmm, sizeof(*mm));
- if (!mm_init(mm, tsk, mm->user_ns))
- goto fail_nomem;
- 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;
- mm_init_owner(mm, NULL);
- mmput(mm);
- fail_nomem:
- return NULL;
- }
- static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
- {
- struct mm_struct *mm, *oldmm;
- 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;
- tsk->last_switch_time = 0;
- #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) {
- mmget(oldmm);
- mm = oldmm;
- } else {
- mm = dup_mm(tsk, current->mm);
- if (!mm)
- return -ENOMEM;
- }
- tsk->mm = mm;
- tsk->active_mm = mm;
- return 0;
- }
- 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, NR_OPEN_MAX, &error);
- if (!newf)
- goto out;
- tsk->files = newf;
- error = 0;
- out:
- return error;
- }
- static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
- {
- struct sighand_struct *sig;
- if (clone_flags & CLONE_SIGHAND) {
- refcount_inc(¤t->sighand->count);
- return 0;
- }
- sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
- RCU_INIT_POINTER(tsk->sighand, sig);
- if (!sig)
- return -ENOMEM;
- refcount_set(&sig->count, 1);
- spin_lock_irq(¤t->sighand->siglock);
- memcpy(sig->action, current->sighand->action, sizeof(sig->action));
- spin_unlock_irq(¤t->sighand->siglock);
- /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
- if (clone_flags & CLONE_CLEAR_SIGHAND)
- flush_signal_handlers(tsk, 0);
- return 0;
- }
- void __cleanup_sighand(struct sighand_struct *sighand)
- {
- if (refcount_dec_and_test(&sighand->count)) {
- signalfd_cleanup(sighand);
- /*
- * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
- * without an RCU grace period, see __lock_task_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)
- {
- struct posix_cputimers *pct = &sig->posix_cputimers;
- unsigned long cpu_limit;
- cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
- posix_cputimers_group_init(pct, cpu_limit);
- }
- 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;
- sig->quick_threads = 1;
- atomic_set(&sig->live, 1);
- refcount_set(&sig->sigcnt, 1);
- /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
- sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
- tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
- init_waitqueue_head(&sig->wait_chldexit);
- sig->curr_target = tsk;
- init_sigpending(&sig->shared_pending);
- INIT_HLIST_HEAD(&sig->multiprocess);
- seqlock_init(&sig->stats_lock);
- prev_cputime_init(&sig->prev_cputime);
- #ifdef CONFIG_POSIX_TIMERS
- INIT_LIST_HEAD(&sig->posix_timers);
- hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- sig->real_timer.function = it_real_fn;
- #endif
- 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);
- sig->oom_score_adj = current->signal->oom_score_adj;
- sig->oom_score_adj_min = current->signal->oom_score_adj_min;
- mutex_init(&sig->cred_guard_mutex);
- init_rwsem(&sig->exec_update_lock);
- return 0;
- }
- static void copy_seccomp(struct task_struct *p)
- {
- #ifdef CONFIG_SECCOMP
- /*
- * Must be called with sighand->lock held, which is common to
- * all threads in the group. Holding cred_guard_mutex is not
- * needed because this new task is not yet running and cannot
- * be racing exec.
- */
- assert_spin_locked(¤t->sighand->siglock);
- /* Ref-count the new filter user, and assign it. */
- get_seccomp_filter(current);
- p->seccomp = current->seccomp;
- /*
- * Explicitly enable no_new_privs here in case it got set
- * between the task_struct being duplicated and holding the
- * sighand lock. The seccomp state and nnp must be in sync.
- */
- if (task_no_new_privs(current))
- task_set_no_new_privs(p);
- /*
- * If the parent gained a seccomp mode after copying thread
- * flags and between before we held the sighand lock, we have
- * to manually enable the seccomp thread flag here.
- */
- if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
- set_task_syscall_work(p, SECCOMP);
- #endif
- }
- 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_CACHED;
- p->pi_top_task = NULL;
- p->pi_blocked_on = NULL;
- #endif
- }
- static inline void init_task_pid_links(struct task_struct *task)
- {
- enum pid_type type;
- for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
- INIT_HLIST_NODE(&task->pid_links[type]);
- }
- static inline void
- init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
- {
- if (type == PIDTYPE_PID)
- task->thread_pid = pid;
- else
- task->signal->pids[type] = pid;
- }
- static inline void rcu_copy_process(struct task_struct *p)
- {
- #ifdef CONFIG_PREEMPT_RCU
- p->rcu_read_lock_nesting = 0;
- p->rcu_read_unlock_special.s = 0;
- p->rcu_blocked_node = NULL;
- INIT_LIST_HEAD(&p->rcu_node_entry);
- #endif /* #ifdef CONFIG_PREEMPT_RCU */
- #ifdef CONFIG_TASKS_RCU
- p->rcu_tasks_holdout = false;
- INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
- p->rcu_tasks_idle_cpu = -1;
- #endif /* #ifdef CONFIG_TASKS_RCU */
- #ifdef CONFIG_TASKS_TRACE_RCU
- p->trc_reader_nesting = 0;
- p->trc_reader_special.s = 0;
- INIT_LIST_HEAD(&p->trc_holdout_list);
- INIT_LIST_HEAD(&p->trc_blkd_node);
- #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
- }
- struct pid *pidfd_pid(const struct file *file)
- {
- if (file->f_op == &pidfd_fops)
- return file->private_data;
- return ERR_PTR(-EBADF);
- }
- static int pidfd_release(struct inode *inode, struct file *file)
- {
- struct pid *pid = file->private_data;
- file->private_data = NULL;
- put_pid(pid);
- return 0;
- }
- #ifdef CONFIG_PROC_FS
- /**
- * pidfd_show_fdinfo - print information about a pidfd
- * @m: proc fdinfo file
- * @f: file referencing a pidfd
- *
- * Pid:
- * This function will print the pid that a given pidfd refers to in the
- * pid namespace of the procfs instance.
- * If the pid namespace of the process is not a descendant of the pid
- * namespace of the procfs instance 0 will be shown as its pid. This is
- * similar to calling getppid() on a process whose parent is outside of
- * its pid namespace.
- *
- * NSpid:
- * If pid namespaces are supported then this function will also print
- * the pid of a given pidfd refers to for all descendant pid namespaces
- * starting from the current pid namespace of the instance, i.e. the
- * Pid field and the first entry in the NSpid field will be identical.
- * If the pid namespace of the process is not a descendant of the pid
- * namespace of the procfs instance 0 will be shown as its first NSpid
- * entry and no others will be shown.
- * Note that this differs from the Pid and NSpid fields in
- * /proc/<pid>/status where Pid and NSpid are always shown relative to
- * the pid namespace of the procfs instance. The difference becomes
- * obvious when sending around a pidfd between pid namespaces from a
- * different branch of the tree, i.e. where no ancestral relation is
- * present between the pid namespaces:
- * - create two new pid namespaces ns1 and ns2 in the initial pid
- * namespace (also take care to create new mount namespaces in the
- * new pid namespace and mount procfs)
- * - create a process with a pidfd in ns1
- * - send pidfd from ns1 to ns2
- * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
- * have exactly one entry, which is 0
- */
- static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
- {
- struct pid *pid = f->private_data;
- struct pid_namespace *ns;
- pid_t nr = -1;
- if (likely(pid_has_task(pid, PIDTYPE_PID))) {
- ns = proc_pid_ns(file_inode(m->file)->i_sb);
- nr = pid_nr_ns(pid, ns);
- }
- seq_put_decimal_ll(m, "Pid:\t", nr);
- #ifdef CONFIG_PID_NS
- seq_put_decimal_ll(m, "\nNSpid:\t", nr);
- if (nr > 0) {
- int i;
- /* If nr is non-zero it means that 'pid' is valid and that
- * ns, i.e. the pid namespace associated with the procfs
- * instance, is in the pid namespace hierarchy of pid.
- * Start at one below the already printed level.
- */
- for (i = ns->level + 1; i <= pid->level; i++)
- seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
- }
- #endif
- seq_putc(m, '\n');
- }
- #endif
- /*
- * Poll support for process exit notification.
- */
- static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
- {
- struct pid *pid = file->private_data;
- __poll_t poll_flags = 0;
- poll_wait(file, &pid->wait_pidfd, pts);
- /*
- * Inform pollers only when the whole thread group exits.
- * If the thread group leader exits before all other threads in the
- * group, then poll(2) should block, similar to the wait(2) family.
- */
- if (thread_group_exited(pid))
- poll_flags = EPOLLIN | EPOLLRDNORM;
- return poll_flags;
- }
- const struct file_operations pidfd_fops = {
- .release = pidfd_release,
- .poll = pidfd_poll,
- #ifdef CONFIG_PROC_FS
- .show_fdinfo = pidfd_show_fdinfo,
- #endif
- };
- static void __delayed_free_task(struct rcu_head *rhp)
- {
- struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
- free_task(tsk);
- }
- static __always_inline void delayed_free_task(struct task_struct *tsk)
- {
- if (IS_ENABLED(CONFIG_MEMCG))
- call_rcu(&tsk->rcu, __delayed_free_task);
- else
- free_task(tsk);
- }
- static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
- {
- /* Skip if kernel thread */
- if (!tsk->mm)
- return;
- /* Skip if spawning a thread or using vfork */
- if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
- return;
- /* We need to synchronize with __set_oom_adj */
- mutex_lock(&oom_adj_mutex);
- set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
- /* Update the values in case they were changed after copy_signal */
- tsk->signal->oom_score_adj = current->signal->oom_score_adj;
- tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
- mutex_unlock(&oom_adj_mutex);
- }
- #ifdef CONFIG_RV
- static void rv_task_fork(struct task_struct *p)
- {
- int i;
- for (i = 0; i < RV_PER_TASK_MONITORS; i++)
- p->rv[i].da_mon.monitoring = false;
- }
- #else
- #define rv_task_fork(p) do {} while (0)
- #endif
- /*
- * 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 __latent_entropy struct task_struct *copy_process(
- struct pid *pid,
- int trace,
- int node,
- struct kernel_clone_args *args)
- {
- int pidfd = -1, retval;
- struct task_struct *p;
- struct multiprocess_signals delayed;
- struct file *pidfile = NULL;
- const u64 clone_flags = args->flags;
- struct nsproxy *nsp = current->nsproxy;
- /*
- * Don't allow sharing the root directory with processes in a different
- * namespace
- */
- 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 with the forking task.
- */
- if (clone_flags & CLONE_THREAD) {
- if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
- (task_active_pid_ns(current) != nsp->pid_ns_for_children))
- return ERR_PTR(-EINVAL);
- }
- /*
- * If the new process will be in a different time namespace
- * do not allow it to share VM or a thread group with the forking task.
- */
- if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
- if (nsp->time_ns != nsp->time_ns_for_children)
- return ERR_PTR(-EINVAL);
- }
- if (clone_flags & CLONE_PIDFD) {
- /*
- * - CLONE_DETACHED is blocked so that we can potentially
- * reuse it later for CLONE_PIDFD.
- * - CLONE_THREAD is blocked until someone really needs it.
- */
- if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
- return ERR_PTR(-EINVAL);
- }
- /*
- * Force any signals received before this point to be delivered
- * before the fork happens. Collect up signals sent to multiple
- * processes that happen during the fork and delay them so that
- * they appear to happen after the fork.
- */
- sigemptyset(&delayed.signal);
- INIT_HLIST_NODE(&delayed.node);
- spin_lock_irq(¤t->sighand->siglock);
- if (!(clone_flags & CLONE_THREAD))
- hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
- recalc_sigpending();
- spin_unlock_irq(¤t->sighand->siglock);
- retval = -ERESTARTNOINTR;
- if (task_sigpending(current))
- goto fork_out;
- retval = -ENOMEM;
- p = dup_task_struct(current, node);
- if (!p)
- goto fork_out;
- p->flags &= ~PF_KTHREAD;
- if (args->kthread)
- p->flags |= PF_KTHREAD;
- if (args->io_thread) {
- /*
- * Mark us an IO worker, and block any signal that isn't
- * fatal or STOP
- */
- p->flags |= PF_IO_WORKER;
- siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
- }
- cpufreq_task_times_init(p);
- p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
- /*
- * Clear TID on mm_release()?
- */
- p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
- ftrace_graph_init_task(p);
- rt_mutex_init_task(p);
- lockdep_assert_irqs_enabled();
- #ifdef CONFIG_PROVE_LOCKING
- DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
- #endif
- retval = copy_creds(p, clone_flags);
- if (retval < 0)
- goto bad_fork_free;
- retval = -EAGAIN;
- if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
- if (p->real_cred->user != INIT_USER &&
- !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
- goto bad_fork_cleanup_count;
- }
- current->flags &= ~PF_NPROC_EXCEEDED;
- /*
- * 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 (data_race(nr_threads >= max_threads))
- goto bad_fork_cleanup_count;
- delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
- p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
- p->flags |= PF_FORKNOEXEC;
- 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;
- #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
- p->utimescaled = p->stimescaled = 0;
- #endif
- prev_cputime_init(&p->prev_cputime);
- #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
- seqcount_init(&p->vtime.seqcount);
- p->vtime.starttime = 0;
- p->vtime.state = VTIME_INACTIVE;
- #endif
- #ifdef CONFIG_IO_URING
- p->io_uring = NULL;
- #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;
- #ifdef CONFIG_PSI
- p->psi_flags = 0;
- #endif
- task_io_accounting_init(&p->ioac);
- acct_clear_integrals(p);
- posix_cputimers_init(&p->posix_cputimers);
- p->io_context = NULL;
- audit_set_context(p, NULL);
- cgroup_fork(p);
- if (args->kthread) {
- if (!set_kthread_struct(p))
- goto bad_fork_cleanup_delayacct;
- }
- #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_delayacct;
- }
- #endif
- #ifdef CONFIG_CPUSETS
- p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
- p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
- seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
- #endif
- #ifdef CONFIG_TRACE_IRQFLAGS
- memset(&p->irqtrace, 0, sizeof(p->irqtrace));
- p->irqtrace.hardirq_disable_ip = _THIS_IP_;
- p->irqtrace.softirq_enable_ip = _THIS_IP_;
- p->softirqs_enabled = 1;
- p->softirq_context = 0;
- #endif
- p->pagefault_disabled = 0;
- #ifdef CONFIG_LOCKDEP
- lockdep_init_task(p);
- #endif
- #ifdef CONFIG_DEBUG_MUTEXES
- p->blocked_on = NULL; /* not blocked yet */
- #endif
- #ifdef CONFIG_BCACHE
- p->sequential_io = 0;
- p->sequential_io_avg = 0;
- #endif
- #ifdef CONFIG_BPF_SYSCALL
- RCU_INIT_POINTER(p->bpf_storage, NULL);
- p->bpf_ctx = NULL;
- #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, clone_flags);
- if (retval)
- goto bad_fork_cleanup_policy;
- retval = audit_alloc(p);
- if (retval)
- goto bad_fork_cleanup_perf;
- /* copy all the process information */
- shm_init_task(p);
- retval = security_task_alloc(p, clone_flags);
- if (retval)
- goto bad_fork_cleanup_audit;
- retval = copy_semundo(clone_flags, p);
- if (retval)
- goto bad_fork_cleanup_security;
- 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(p, args);
- if (retval)
- goto bad_fork_cleanup_io;
- stackleak_task_init(p);
- if (pid != &init_struct_pid) {
- pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
- args->set_tid_size);
- if (IS_ERR(pid)) {
- retval = PTR_ERR(pid);
- goto bad_fork_cleanup_thread;
- }
- }
- /*
- * This has to happen after we've potentially unshared the file
- * descriptor table (so that the pidfd doesn't leak into the child
- * if the fd table isn't shared).
- */
- if (clone_flags & CLONE_PIDFD) {
- retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
- if (retval < 0)
- goto bad_fork_free_pid;
- pidfd = retval;
- pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
- O_RDWR | O_CLOEXEC);
- if (IS_ERR(pidfile)) {
- put_unused_fd(pidfd);
- retval = PTR_ERR(pidfile);
- goto bad_fork_free_pid;
- }
- get_pid(pid); /* held by pidfile now */
- retval = put_user(pidfd, args->pidfd);
- if (retval)
- goto bad_fork_put_pidfd;
- }
- #ifdef CONFIG_BLOCK
- p->plug = NULL;
- #endif
- futex_init_task(p);
- /*
- * sigaltstack should be cleared when sharing the same VM
- */
- if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
- sas_ss_reset(p);
- /*
- * Syscall tracing and stepping should be turned off in the
- * child regardless of CLONE_PTRACE.
- */
- user_disable_single_step(p);
- clear_task_syscall_work(p, SYSCALL_TRACE);
- #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
- clear_task_syscall_work(p, SYSCALL_EMU);
- #endif
- clear_tsk_latency_tracing(p);
- /* ok, now we should be set up.. */
- p->pid = pid_nr(pid);
- if (clone_flags & CLONE_THREAD) {
- p->group_leader = current->group_leader;
- p->tgid = current->tgid;
- } else {
- 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;
- clear_posix_cputimers_work(p);
- #ifdef CONFIG_KRETPROBES
- p->kretprobe_instances.first = NULL;
- #endif
- #ifdef CONFIG_RETHOOK
- p->rethooks.first = NULL;
- #endif
- /*
- * Ensure that the cgroup subsystem policies allow the new process to be
- * forked. It should be noted that the new process's css_set can be changed
- * between here and cgroup_post_fork() if an organisation operation is in
- * progress.
- */
- retval = cgroup_can_fork(p, args);
- if (retval)
- goto bad_fork_put_pidfd;
- /*
- * Now that the cgroups are pinned, re-clone the parent cgroup and put
- * the new task on the correct runqueue. All this *before* the task
- * becomes visible.
- *
- * This isn't part of ->can_fork() because while the re-cloning is
- * cgroup specific, it unconditionally needs to place the task on a
- * runqueue.
- */
- sched_cgroup_fork(p, args);
- /*
- * From this point on we must avoid any synchronous user-space
- * communication until we take the tasklist-lock. In particular, we do
- * not want user-space to be able to predict the process start-time by
- * stalling fork(2) after we recorded the start_time but before it is
- * visible to the system.
- */
- p->start_time = ktime_get_ns();
- p->start_boottime = ktime_get_boottime_ns();
- /*
- * 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;
- if (clone_flags & CLONE_THREAD)
- p->exit_signal = -1;
- else
- p->exit_signal = current->group_leader->exit_signal;
- } else {
- p->real_parent = current;
- p->parent_exec_id = current->self_exec_id;
- p->exit_signal = args->exit_signal;
- }
- klp_copy_process(p);
- sched_core_fork(p);
- spin_lock(¤t->sighand->siglock);
- rv_task_fork(p);
- rseq_fork(p, clone_flags);
- /* Don't start children in a dying pid namespace */
- if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
- retval = -ENOMEM;
- goto bad_fork_cancel_cgroup;
- }
- /* Let kill terminate clone/fork in the middle */
- if (fatal_signal_pending(current)) {
- retval = -EINTR;
- goto bad_fork_cancel_cgroup;
- }
- /* No more failure paths after this point. */
- /*
- * Copy seccomp details explicitly here, in case they were changed
- * before holding sighand lock.
- */
- copy_seccomp(p);
- init_task_pid_links(p);
- 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_TGID, pid);
- 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->shared_pending.signal = delayed.signal;
- p->signal->tty = tty_kref_get(current->signal->tty);
- /*
- * Inherit has_child_subreaper flag under the same
- * tasklist_lock with adding child to the process tree
- * for propagate_has_child_subreaper optimization.
- */
- p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
- p->real_parent->signal->is_child_subreaper;
- list_add_tail(&p->sibling, &p->real_parent->children);
- list_add_tail_rcu(&p->tasks, &init_task.tasks);
- attach_pid(p, PIDTYPE_TGID);
- attach_pid(p, PIDTYPE_PGID);
- attach_pid(p, PIDTYPE_SID);
- __this_cpu_inc(process_counts);
- } else {
- current->signal->nr_threads++;
- current->signal->quick_threads++;
- atomic_inc(¤t->signal->live);
- refcount_inc(¤t->signal->sigcnt);
- task_join_group_stop(p);
- list_add_tail_rcu(&p->thread_group,
- &p->group_leader->thread_group);
- list_add_tail_rcu(&p->thread_node,
- &p->signal->thread_head);
- }
- attach_pid(p, PIDTYPE_PID);
- nr_threads++;
- }
- trace_android_vh_copy_process(current, nr_threads, current->signal->nr_threads);
- total_forks++;
- hlist_del_init(&delayed.node);
- spin_unlock(¤t->sighand->siglock);
- syscall_tracepoint_update(p);
- write_unlock_irq(&tasklist_lock);
- if (pidfile)
- fd_install(pidfd, pidfile);
- proc_fork_connector(p);
- sched_post_fork(p);
- cgroup_post_fork(p, args);
- perf_event_fork(p);
- trace_task_newtask(p, clone_flags);
- uprobe_copy_process(p, clone_flags);
- copy_oom_score_adj(clone_flags, p);
- #ifdef CONFIG_KDP_CRED
- if (kdp_enable)
- kdp_assign_pgd(p);
- #endif
- return p;
- bad_fork_cancel_cgroup:
- sched_core_free(p);
- spin_unlock(¤t->sighand->siglock);
- write_unlock_irq(&tasklist_lock);
- cgroup_cancel_fork(p, args);
- bad_fork_put_pidfd:
- if (clone_flags & CLONE_PIDFD) {
- fput(pidfile);
- put_unused_fd(pidfd);
- }
- bad_fork_free_pid:
- if (pid != &init_struct_pid)
- free_pid(pid);
- bad_fork_cleanup_thread:
- exit_thread(p);
- 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) {
- mm_clear_owner(p->mm, p);
- 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_security:
- security_task_free(p);
- bad_fork_cleanup_audit:
- audit_free(p);
- bad_fork_cleanup_perf:
- perf_event_free_task(p);
- bad_fork_cleanup_policy:
- lockdep_free_task(p);
- #ifdef CONFIG_NUMA
- mpol_put(p->mempolicy);
- #endif
- bad_fork_cleanup_delayacct:
- delayacct_tsk_free(p);
- bad_fork_cleanup_count:
- dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
- exit_creds(p);
- bad_fork_free:
- WRITE_ONCE(p->__state, TASK_DEAD);
- exit_task_stack_account(p);
- put_task_stack(p);
- delayed_free_task(p);
- fork_out:
- spin_lock_irq(¤t->sighand->siglock);
- hlist_del_init(&delayed.node);
- spin_unlock_irq(¤t->sighand->siglock);
- return ERR_PTR(retval);
- }
- static inline void init_idle_pids(struct task_struct *idle)
- {
- enum pid_type type;
- for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
- INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
- init_task_pid(idle, type, &init_struct_pid);
- }
- }
- static int idle_dummy(void *dummy)
- {
- /* This function is never called */
- return 0;
- }
- struct task_struct * __init fork_idle(int cpu)
- {
- struct task_struct *task;
- struct kernel_clone_args args = {
- .flags = CLONE_VM,
- .fn = &idle_dummy,
- .fn_arg = NULL,
- .kthread = 1,
- .idle = 1,
- };
- task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
- if (!IS_ERR(task)) {
- init_idle_pids(task);
- init_idle(task, cpu);
- }
- return task;
- }
- /*
- * This is like kernel_clone(), but shaved down and tailored to just
- * creating io_uring workers. It returns a created task, or an error pointer.
- * The returned task is inactive, and the caller must fire it up through
- * wake_up_new_task(p). All signals are blocked in the created task.
- */
- struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
- {
- unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
- CLONE_IO;
- struct kernel_clone_args args = {
- .flags = ((lower_32_bits(flags) | CLONE_VM |
- CLONE_UNTRACED) & ~CSIGNAL),
- .exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .fn = fn,
- .fn_arg = arg,
- .io_thread = 1,
- };
- return copy_process(NULL, 0, node, &args);
- }
- /*
- * 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.
- *
- * args->exit_signal is expected to be checked for sanity by the caller.
- */
- pid_t kernel_clone(struct kernel_clone_args *args)
- {
- u64 clone_flags = args->flags;
- struct completion vfork;
- struct pid *pid;
- struct task_struct *p;
- int trace = 0;
- pid_t nr;
- /*
- * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
- * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
- * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
- * field in struct clone_args and it still doesn't make sense to have
- * them both point at the same memory location. Performing this check
- * here has the advantage that we don't need to have a separate helper
- * to check for legacy clone().
- */
- if ((args->flags & CLONE_PIDFD) &&
- (args->flags & CLONE_PARENT_SETTID) &&
- (args->pidfd == args->parent_tid))
- return -EINVAL;
- /*
- * 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 (args->exit_signal != SIGCHLD)
- trace = PTRACE_EVENT_CLONE;
- else
- trace = PTRACE_EVENT_FORK;
- if (likely(!ptrace_event_enabled(current, trace)))
- trace = 0;
- }
- p = copy_process(NULL, trace, NUMA_NO_NODE, args);
- add_latent_entropy();
- if (IS_ERR(p))
- return PTR_ERR(p);
- cpufreq_task_times_alloc(p);
- /*
- * Do this prior waking up the new thread - the thread pointer
- * might get invalid after that point, if the thread exits quickly.
- */
- trace_sched_process_fork(current, p);
- pid = get_task_pid(p, PIDTYPE_PID);
- nr = pid_vnr(pid);
- if (clone_flags & CLONE_PARENT_SETTID)
- put_user(nr, args->parent_tid);
- if (clone_flags & CLONE_VFORK) {
- p->vfork_done = &vfork;
- init_completion(&vfork);
- get_task_struct(p);
- }
- if (IS_ENABLED(CONFIG_LRU_GEN) && !(clone_flags & CLONE_VM)) {
- /* lock the task to synchronize with memcg migration */
- task_lock(p);
- lru_gen_add_mm(p->mm);
- task_unlock(p);
- }
- wake_up_new_task(p);
- /* forking complete and child started to run, tell ptracer */
- if (unlikely(trace))
- ptrace_event_pid(trace, pid);
- if (clone_flags & CLONE_VFORK) {
- if (!wait_for_vfork_done(p, &vfork))
- ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
- }
- put_pid(pid);
- return nr;
- }
- /*
- * Create a kernel thread.
- */
- pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
- {
- struct kernel_clone_args args = {
- .flags = ((lower_32_bits(flags) | CLONE_VM |
- CLONE_UNTRACED) & ~CSIGNAL),
- .exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .fn = fn,
- .fn_arg = arg,
- .kthread = 1,
- };
- return kernel_clone(&args);
- }
- /*
- * Create a user mode thread.
- */
- pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
- {
- struct kernel_clone_args args = {
- .flags = ((lower_32_bits(flags) | CLONE_VM |
- CLONE_UNTRACED) & ~CSIGNAL),
- .exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .fn = fn,
- .fn_arg = arg,
- };
- return kernel_clone(&args);
- }
- #ifdef __ARCH_WANT_SYS_FORK
- SYSCALL_DEFINE0(fork)
- {
- #ifdef CONFIG_MMU
- struct kernel_clone_args args = {
- .exit_signal = SIGCHLD,
- };
- return kernel_clone(&args);
- #else
- /* can not support in nommu mode */
- return -EINVAL;
- #endif
- }
- #endif
- #ifdef __ARCH_WANT_SYS_VFORK
- SYSCALL_DEFINE0(vfork)
- {
- struct kernel_clone_args args = {
- .flags = CLONE_VFORK | CLONE_VM,
- .exit_signal = SIGCHLD,
- };
- return kernel_clone(&args);
- }
- #endif
- #ifdef __ARCH_WANT_SYS_CLONE
- #ifdef CONFIG_CLONE_BACKWARDS
- SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
- int __user *, parent_tidptr,
- unsigned long, tls,
- 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,
- unsigned long, tls)
- #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,
- unsigned long, tls)
- #else
- SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
- int __user *, parent_tidptr,
- int __user *, child_tidptr,
- unsigned long, tls)
- #endif
- {
- struct kernel_clone_args args = {
- .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
- .pidfd = parent_tidptr,
- .child_tid = child_tidptr,
- .parent_tid = parent_tidptr,
- .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
- .stack = newsp,
- .tls = tls,
- };
- return kernel_clone(&args);
- }
- #endif
- #ifdef __ARCH_WANT_SYS_CLONE3
- noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
- struct clone_args __user *uargs,
- size_t usize)
- {
- int err;
- struct clone_args args;
- pid_t *kset_tid = kargs->set_tid;
- BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
- CLONE_ARGS_SIZE_VER0);
- BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
- CLONE_ARGS_SIZE_VER1);
- BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
- CLONE_ARGS_SIZE_VER2);
- BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
- if (unlikely(usize > PAGE_SIZE))
- return -E2BIG;
- if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
- return -EINVAL;
- err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
- if (err)
- return err;
- if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
- return -EINVAL;
- if (unlikely(!args.set_tid && args.set_tid_size > 0))
- return -EINVAL;
- if (unlikely(args.set_tid && args.set_tid_size == 0))
- return -EINVAL;
- /*
- * Verify that higher 32bits of exit_signal are unset and that
- * it is a valid signal
- */
- if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
- !valid_signal(args.exit_signal)))
- return -EINVAL;
- if ((args.flags & CLONE_INTO_CGROUP) &&
- (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
- return -EINVAL;
- *kargs = (struct kernel_clone_args){
- .flags = args.flags,
- .pidfd = u64_to_user_ptr(args.pidfd),
- .child_tid = u64_to_user_ptr(args.child_tid),
- .parent_tid = u64_to_user_ptr(args.parent_tid),
- .exit_signal = args.exit_signal,
- .stack = args.stack,
- .stack_size = args.stack_size,
- .tls = args.tls,
- .set_tid_size = args.set_tid_size,
- .cgroup = args.cgroup,
- };
- if (args.set_tid &&
- copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
- (kargs->set_tid_size * sizeof(pid_t))))
- return -EFAULT;
- kargs->set_tid = kset_tid;
- return 0;
- }
- /**
- * clone3_stack_valid - check and prepare stack
- * @kargs: kernel clone args
- *
- * Verify that the stack arguments userspace gave us are sane.
- * In addition, set the stack direction for userspace since it's easy for us to
- * determine.
- */
- static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
- {
- if (kargs->stack == 0) {
- if (kargs->stack_size > 0)
- return false;
- } else {
- if (kargs->stack_size == 0)
- return false;
- if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
- return false;
- #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
- kargs->stack += kargs->stack_size;
- #endif
- }
- return true;
- }
- static bool clone3_args_valid(struct kernel_clone_args *kargs)
- {
- /* Verify that no unknown flags are passed along. */
- if (kargs->flags &
- ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
- return false;
- /*
- * - make the CLONE_DETACHED bit reusable for clone3
- * - make the CSIGNAL bits reusable for clone3
- */
- if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
- return false;
- if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
- (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
- return false;
- if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
- kargs->exit_signal)
- return false;
- if (!clone3_stack_valid(kargs))
- return false;
- return true;
- }
- /**
- * clone3 - create a new process with specific properties
- * @uargs: argument structure
- * @size: size of @uargs
- *
- * clone3() is the extensible successor to clone()/clone2().
- * It takes a struct as argument that is versioned by its size.
- *
- * Return: On success, a positive PID for the child process.
- * On error, a negative errno number.
- */
- SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
- {
- int err;
- struct kernel_clone_args kargs;
- pid_t set_tid[MAX_PID_NS_LEVEL];
- kargs.set_tid = set_tid;
- err = copy_clone_args_from_user(&kargs, uargs, size);
- if (err)
- return err;
- if (!clone3_args_valid(&kargs))
- return -EINVAL;
- return kernel_clone(&kargs);
- }
- #endif
- void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
- {
- struct task_struct *leader, *parent, *child;
- int res;
- read_lock(&tasklist_lock);
- leader = top = top->group_leader;
- down:
- for_each_thread(leader, parent) {
- list_for_each_entry(child, &parent->children, sibling) {
- res = visitor(child, data);
- if (res) {
- if (res < 0)
- goto out;
- leader = child;
- goto down;
- }
- up:
- ;
- }
- }
- if (leader != top) {
- child = leader;
- parent = child->real_parent;
- leader = parent->group_leader;
- goto up;
- }
- out:
- read_unlock(&tasklist_lock);
- }
- #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 mm_cache_init(void)
- {
- unsigned int mm_size;
- /*
- * The mm_cpumask is located at the end of mm_struct, and is
- * dynamically sized based on the maximum CPU number this system
- * can have, taking hotplug into account (nr_cpu_ids).
- */
- mm_size = sizeof(struct mm_struct) + cpumask_size();
- mm_cachep = kmem_cache_create_usercopy("mm_struct",
- mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
- offsetof(struct mm_struct, saved_auxv),
- sizeof_field(struct mm_struct, saved_auxv),
- NULL);
- }
- void __init proc_caches_init(void)
- {
- sighand_cachep = kmem_cache_create("sighand_cache",
- sizeof(struct sighand_struct), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
- SLAB_ACCOUNT, sighand_ctor);
- signal_cachep = kmem_cache_create("signal_cache",
- sizeof(struct signal_struct), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
- NULL);
- files_cachep = kmem_cache_create("files_cache",
- sizeof(struct files_struct), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
- NULL);
- fs_cachep = kmem_cache_create("fs_cache",
- sizeof(struct fs_struct), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
- NULL);
- vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
- #ifdef CONFIG_PER_VMA_LOCK
- vma_lock_cachep = KMEM_CACHE(vma_lock, SLAB_PANIC|SLAB_ACCOUNT);
- #endif
- 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|CLONE_NEWCGROUP|
- CLONE_NEWTIME))
- return -EINVAL;
- /*
- * Not implemented, but pretend it works if there is nothing
- * to unshare. Note that unsharing the address space or the
- * signal handlers also need to unshare the signal queues (aka
- * CLONE_THREAD).
- */
- if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
- if (!thread_group_empty(current))
- return -EINVAL;
- }
- if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
- if (refcount_read(¤t->sighand->count) > 1)
- return -EINVAL;
- }
- if (unshare_flags & CLONE_VM) {
- if (!current_is_single_threaded())
- 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
- */
- int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
- 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, max_fds, &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 kernel_clone() 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.
- */
- int ksys_unshare(unsigned long unshare_flags)
- {
- struct fs_struct *fs, *new_fs = NULL;
- struct files_struct *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 group
- * and unshare the filesystem root and working directories.
- */
- if (unshare_flags & CLONE_NEWUSER)
- unshare_flags |= CLONE_THREAD | CLONE_FS;
- /*
- * If unsharing vm, must also unshare signal handlers.
- */
- if (unshare_flags & CLONE_VM)
- unshare_flags |= CLONE_SIGHAND;
- /*
- * If unsharing a signal handlers, must also unshare the signal queues.
- */
- if (unshare_flags & CLONE_SIGHAND)
- unshare_flags |= CLONE_THREAD;
- /*
- * 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, NR_OPEN_MAX, &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_cred) {
- err = set_cred_ucounts(new_cred);
- 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 (unshare_flags & CLONE_NEWIPC) {
- /* Orphan segments in old ns (see sem above). */
- exit_shm(current);
- shm_init_task(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)
- swap(current->files, new_fd);
- task_unlock(current);
- if (new_cred) {
- /* Install the new user namespace */
- commit_creds(new_cred);
- new_cred = NULL;
- }
- }
- perf_event_namespaces(current);
- 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;
- }
- SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
- {
- return ksys_unshare(unshare_flags);
- }
- /*
- * 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(void)
- {
- struct task_struct *task = current;
- struct files_struct *old, *copy = NULL;
- int error;
- error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
- if (error || !copy)
- return error;
- old = task->files;
- task_lock(task);
- task->files = copy;
- task_unlock(task);
- put_files_struct(old);
- return 0;
- }
- int sysctl_max_threads(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
- {
- struct ctl_table t;
- int ret;
- int threads = max_threads;
- int min = 1;
- int max = MAX_THREADS;
- t = *table;
- t.data = &threads;
- t.extra1 = &min;
- t.extra2 = &max;
- ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
- if (ret || !write)
- return ret;
- max_threads = threads;
- return 0;
- }
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