diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 3554 |
1 files changed, 3554 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c new file mode 100644 index 0000000000..177ce7438d --- /dev/null +++ b/kernel/fork.c @@ -0,0 +1,3554 @@ +// 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/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/stackprotector.h> +#include <linux/user_events.h> +#include <linux/iommu.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; + int nr_charged = 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; + nr_charged++; + } + return 0; +err: + for (i = 0; i < nr_charged; 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); + vma_numab_state_init(new); + dup_anon_vma_name(orig, new); + + return new; +} + +void __vm_area_free(struct vm_area_struct *vma) +{ + vma_numab_state_free(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 + 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); + 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); + VMA_ITERATOR(old_vmi, oldmm, 0); + VMA_ITERATOR(vmi, mm, 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); + + retval = vma_iter_bulk_alloc(&vmi, oldmm->map_count); + if (retval) + goto out; + + mt_clear_in_rcu(vmi.mas.tree); + for_each_vma(old_vmi, mpnt) { + struct file *file; + + vma_start_write(mpnt); + 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 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 */ + if (vma_iter_bulk_store(&vmi, tmp)) + goto fail_nomem_vmi_store; + + 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 loop_out; + } + /* a new mm has just been created */ + retval = arch_dup_mmap(oldmm, mm); +loop_out: + vma_iter_free(&vmi); + if (!retval) + mt_set_in_rcu(vmi.mas.tree); +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_vmi_store: + unlink_anon_vmas(tmp); +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 = percpu_counter_sum(&mm->rss_stat[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))) + +static void do_check_lazy_tlb(void *arg) +{ + struct mm_struct *mm = arg; + + WARN_ON_ONCE(current->active_mm == mm); +} + +static void do_shoot_lazy_tlb(void *arg) +{ + struct mm_struct *mm = arg; + + if (current->active_mm == mm) { + WARN_ON_ONCE(current->mm); + current->active_mm = &init_mm; + switch_mm(mm, &init_mm, current); + } +} + +static void cleanup_lazy_tlbs(struct mm_struct *mm) +{ + if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) { + /* + * In this case, lazy tlb mms are refounted and would not reach + * __mmdrop until all CPUs have switched away and mmdrop()ed. + */ + return; + } + + /* + * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it + * requires lazy mm users to switch to another mm when the refcount + * drops to zero, before the mm is freed. This requires IPIs here to + * switch kernel threads to init_mm. + * + * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm + * switch with the final userspace teardown TLB flush which leaves the + * mm lazy on this CPU but no others, reducing the need for additional + * IPIs here. There are cases where a final IPI is still required here, + * such as the final mmdrop being performed on a different CPU than the + * one exiting, or kernel threads using the mm when userspace exits. + * + * IPI overheads have not found to be expensive, but they could be + * reduced in a number of possible ways, for example (roughly + * increasing order of complexity): + * - The last lazy reference created by exit_mm() could instead switch + * to init_mm, however it's probable this will run on the same CPU + * immediately afterwards, so this may not reduce IPIs much. + * - A batch of mms requiring IPIs could be gathered and freed at once. + * - CPUs store active_mm where it can be remotely checked without a + * lock, to filter out false-positives in the cpumask. + * - After mm_users or mm_count reaches zero, switching away from the + * mm could clear mm_cpumask to reduce some IPIs, perhaps together + * with some batching or delaying of the final IPIs. + * - A delayed freeing and RCU-like quiescing sequence based on mm + * switching to avoid IPIs completely. + */ + on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1); + if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES)) + on_each_cpu(do_check_lazy_tlb, (void *)mm, 1); +} + +/* + * 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); + + /* Ensure no CPUs are using this as their lazy tlb mm */ + cleanup_lazy_tlbs(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); + mm_destroy_cid(mm); + percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS); + + 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_disk = 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 + +#ifdef CONFIG_SCHED_MM_CID + tsk->mm_cid = -1; + tsk->last_mm_cid = -1; + tsk->mm_cid_active = 0; + tsk->migrate_from_cpu = -1; +#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) +{ + 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 = mmf_init_flags(current->mm->flags); + 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; + + if (mm_alloc_cid(mm)) + goto fail_cid; + + if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT, + NR_MM_COUNTERS)) + goto fail_pcpu; + + mm->user_ns = get_user_ns(user_ns); + lru_gen_init_mm(mm); + return mm; + +fail_pcpu: + mm_destroy_cid(mm); +fail_cid: + destroy_context(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)) + __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 it happens before + * the new mm is made visible to anyone. + * + * 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). + * + * 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; + } + + ret = deny_write_access(new_exe_file); + if (ret) + return -EACCES; + get_file(new_exe_file); + + /* set the new file */ + mmap_write_lock(mm); + old_exe_file = rcu_dereference_raw(mm->exe_file); + rcu_assign_pointer(mm->exe_file, new_exe_file); + mmap_write_unlock(mm); + + if (old_exe_file) { + allow_write_access(old_exe_file); + fput(old_exe_file); + } + 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; + sched_mm_cid_fork(tsk); + 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, + int no_files) +{ + struct files_struct *oldf, *newf; + int error = 0; + + /* + * A background process may not have any files ... + */ + oldf = current->files; + if (!oldf) + goto out; + + if (no_files) { + tsk->files = NULL; + 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 +}; + +/** + * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd + * @pid: the struct pid for which to create a pidfd + * @flags: flags of the new @pidfd + * @pidfd: the pidfd to return + * + * Allocate a new file that stashes @pid and reserve a new pidfd number in the + * caller's file descriptor table. The pidfd is reserved but not installed yet. + + * The helper doesn't perform checks on @pid which makes it useful for pidfds + * created via CLONE_PIDFD where @pid has no task attached when the pidfd and + * pidfd file are prepared. + * + * If this function returns successfully the caller is responsible to either + * call fd_install() passing the returned pidfd and pidfd file as arguments in + * order to install the pidfd into its file descriptor table or they must use + * put_unused_fd() and fput() on the returned pidfd and pidfd file + * respectively. + * + * This function is useful when a pidfd must already be reserved but there + * might still be points of failure afterwards and the caller wants to ensure + * that no pidfd is leaked into its file descriptor table. + * + * Return: On success, a reserved pidfd is returned from the function and a new + * pidfd file is returned in the last argument to the function. On + * error, a negative error code is returned from the function and the + * last argument remains unchanged. + */ +static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) +{ + int pidfd; + struct file *pidfd_file; + + if (flags & ~(O_NONBLOCK | O_RDWR | O_CLOEXEC)) + return -EINVAL; + + pidfd = get_unused_fd_flags(O_RDWR | O_CLOEXEC); + if (pidfd < 0) + return pidfd; + + pidfd_file = anon_inode_getfile("[pidfd]", &pidfd_fops, pid, + flags | O_RDWR | O_CLOEXEC); + if (IS_ERR(pidfd_file)) { + put_unused_fd(pidfd); + return PTR_ERR(pidfd_file); + } + get_pid(pid); /* held by pidfd_file now */ + *ret = pidfd_file; + return pidfd; +} + +/** + * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd + * @pid: the struct pid for which to create a pidfd + * @flags: flags of the new @pidfd + * @pidfd: the pidfd to return + * + * Allocate a new file that stashes @pid and reserve a new pidfd number in the + * caller's file descriptor table. The pidfd is reserved but not installed yet. + * + * The helper verifies that @pid is used as a thread group leader. + * + * If this function returns successfully the caller is responsible to either + * call fd_install() passing the returned pidfd and pidfd file as arguments in + * order to install the pidfd into its file descriptor table or they must use + * put_unused_fd() and fput() on the returned pidfd and pidfd file + * respectively. + * + * This function is useful when a pidfd must already be reserved but there + * might still be points of failure afterwards and the caller wants to ensure + * that no pidfd is leaked into its file descriptor table. + * + * Return: On success, a reserved pidfd is returned from the function and a new + * pidfd file is returned in the last argument to the function. On + * error, a negative error code is returned from the function and the + * last argument remains unchanged. + */ +int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) +{ + if (!pid || !pid_has_task(pid, PIDTYPE_TGID)) + return -EINVAL; + + return __pidfd_prepare(pid, flags, ret); +} + +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. + */ +__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 (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->user_worker) { + /* + * Mark us a user worker, and block any signal that isn't + * fatal or STOP + */ + p->flags |= PF_USER_WORKER; + siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP)); + } + if (args->io_thread) + p->flags |= PF_IO_WORKER; + + if (args->name) + strscpy_pad(p->comm, args->name, sizeof(p->comm)); + + 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, args->no_files); + 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) { + /* Note that no task has been attached to @pid yet. */ + retval = __pidfd_prepare(pid, O_RDWR | O_CLOEXEC, &pidfile); + if (retval < 0) + goto bad_fork_free_pid; + pidfd = retval; + + 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++; + } + 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); + user_events_fork(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; +} + +/* + * 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, + .user_worker = 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); + } + + 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, const char *name, + 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, + .name = name, + .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_cid_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; +} |