| // 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/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/vmacache.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/sched/mm.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> |
| |
| /* |
| * Minimum number of threads to boot the kernel |
| */ |
| #define MIN_THREADS 20 |
| |
| /* |
| * Maximum number of threads |
| */ |
| #define MAX_THREADS FUTEX_TID_MASK |
| |
| /* |
| * 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 */ |
| |
| #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; |
| |
| 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) |
| vma_init(vma, mm); |
| 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) { |
| 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. |
| */ |
| *new = data_race(*orig); |
| INIT_LIST_HEAD(&new->anon_vma_chain); |
| new->vm_next = new->vm_prev = NULL; |
| dup_anon_vma_name(orig, new); |
| } |
| return new; |
| } |
| |
| void vm_area_free(struct vm_area_struct *vma) |
| { |
| free_anon_vma_name(vma); |
| kmem_cache_free(vm_area_cachep, vma); |
| } |
| |
| 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) |
| { |
| release_user_cpus_ptr(tsk); |
| scs_release(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); |
| 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, *prev, **pprev; |
| struct rb_node **rb_link, *rb_parent; |
| int retval; |
| unsigned long charge; |
| LIST_HEAD(uf); |
| |
| 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; |
| |
| rb_link = &mm->mm_rb.rb_node; |
| rb_parent = NULL; |
| pprev = &mm->mmap; |
| retval = ksm_fork(mm, oldmm); |
| if (retval) |
| goto out; |
| khugepaged_fork(mm, oldmm); |
| |
| 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, -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 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; |
| tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT); |
| 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); |
| } |
| |
| /* |
| * 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++; |
| 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) |
| goto out; |
| } |
| /* a new mm has just been created */ |
| retval = arch_dup_mmap(oldmm, mm); |
| 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 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); |
| bpf_task_storage_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 __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 < MAX_PER_NAMESPACE_UCOUNTS; i++) |
| init_user_ns.ucount_max[i] = max_threads/2; |
| |
| set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY); |
| set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY); |
| set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY); |
| set_rlimit_ucount_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); |
| 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 |
| |
| 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) |
| { |
| mm->mmap = NULL; |
| mm->mm_rb = RB_ROOT; |
| mm->vmacache_seqnum = 0; |
| 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); |
| 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); |
| 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); |
| 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)) |
| __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); |
| } |
| } |
| #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) { |
| mmap_read_lock(mm); |
| for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) { |
| if (!vma->vm_file) |
| continue; |
| if (path_equal(&vma->vm_file->f_path, |
| &old_exe_file->f_path)) |
| ret = -EBUSY; |
| } |
| 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) |
| { |
| int killed; |
| |
| freezer_do_not_count(); |
| cgroup_enter_frozen(); |
| killed = wait_for_completion_killable(vfork); |
| cgroup_leave_frozen(false); |
| 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 |
| */ |
| 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; |
| |
| /* initialize the new vmacache entries */ |
| vmacache_flush(tsk); |
| |
| 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; |
| 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. |
| * |
| * On vfork, the child process enters the target time namespace only |
| * after exec. |
| */ |
| if ((clone_flags & (CLONE_VM | CLONE_VFORK)) == 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)); |
| } |
| |
| 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_ucounts_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); |
| |
| /* |
| * Copy seccomp details explicitly here, in case they were changed |
| * before holding sighand lock. |
| */ |
| copy_seccomp(p); |
| |
| 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; |
| } |
| |
| 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++; |
| 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++; |
| } |
| 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); |
| |
| 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; |
| } |
| |
| struct mm_struct *copy_init_mm(void) |
| { |
| return dup_mm(NULL, &init_mm); |
| } |
| |
| /* |
| * 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); |
| |
| /* |
| * 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); |
| } |
| |
| 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)) |
| 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 proc_caches_init(void) |
| { |
| unsigned int mm_size; |
| |
| 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); |
| |
| /* |
| * 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); |
| vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); |
| 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 *b
|