9a3a04ac38
This reverts commit 0130b0b32e
.
Sergey Vlasov points out (and Vadim Lobanov concurs) that the bug it was
supposed to fix must be some unrelated memory corruption, and the "fix"
actually causes more problems:
"However, the new code does not look safe in all cases. If some other
task has opened more files while dup_fd() released oldf->file_lock, the
new code will update open_files to the new larger value. But newf was
allocated with the old smaller value of open_files, therefore subsequent
accesses to newf may try to write into unallocated memory."
so revert it.
Cc: Sharyathi Nagesh <sharyath@in.ibm.com>
Cc: Sergey Vlasov <vsu@altlinux.ru>
Cc: Vadim Lobanov <vlobanov@speakeasy.net>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1753 lines
42 KiB
C
1753 lines
42 KiB
C
/*
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* linux/kernel/fork.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* 'fork.c' contains the help-routines for the 'fork' system call
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* (see also entry.S and others).
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* Fork is rather simple, once you get the hang of it, but the memory
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* management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
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*/
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/unistd.h>
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#include <linux/smp_lock.h>
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/completion.h>
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#include <linux/namespace.h>
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#include <linux/personality.h>
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#include <linux/mempolicy.h>
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#include <linux/sem.h>
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#include <linux/file.h>
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#include <linux/key.h>
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#include <linux/binfmts.h>
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#include <linux/mman.h>
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#include <linux/fs.h>
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#include <linux/nsproxy.h>
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#include <linux/capability.h>
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#include <linux/cpu.h>
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#include <linux/cpuset.h>
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#include <linux/security.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/jiffies.h>
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#include <linux/futex.h>
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#include <linux/rcupdate.h>
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#include <linux/ptrace.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/profile.h>
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#include <linux/rmap.h>
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#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/delayacct.h>
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#include <linux/taskstats_kern.h>
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#include <linux/random.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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/*
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* Protected counters by write_lock_irq(&tasklist_lock)
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*/
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unsigned long total_forks; /* Handle normal Linux uptimes. */
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int nr_threads; /* The idle threads do not count.. */
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int max_threads; /* tunable limit on nr_threads */
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DEFINE_PER_CPU(unsigned long, process_counts) = 0;
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__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
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int nr_processes(void)
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{
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int cpu;
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int total = 0;
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for_each_online_cpu(cpu)
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total += per_cpu(process_counts, cpu);
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return total;
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}
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
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# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
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static kmem_cache_t *task_struct_cachep;
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#endif
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/* SLAB cache for signal_struct structures (tsk->signal) */
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static kmem_cache_t *signal_cachep;
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/* SLAB cache for sighand_struct structures (tsk->sighand) */
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kmem_cache_t *sighand_cachep;
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/* SLAB cache for files_struct structures (tsk->files) */
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kmem_cache_t *files_cachep;
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/* SLAB cache for fs_struct structures (tsk->fs) */
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kmem_cache_t *fs_cachep;
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/* SLAB cache for vm_area_struct structures */
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kmem_cache_t *vm_area_cachep;
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/* SLAB cache for mm_struct structures (tsk->mm) */
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static kmem_cache_t *mm_cachep;
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void free_task(struct task_struct *tsk)
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{
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free_thread_info(tsk->thread_info);
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rt_mutex_debug_task_free(tsk);
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free_task_struct(tsk);
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}
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EXPORT_SYMBOL(free_task);
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void __put_task_struct(struct task_struct *tsk)
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{
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WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
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WARN_ON(atomic_read(&tsk->usage));
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WARN_ON(tsk == current);
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security_task_free(tsk);
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free_uid(tsk->user);
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put_group_info(tsk->group_info);
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delayacct_tsk_free(tsk);
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if (!profile_handoff_task(tsk))
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free_task(tsk);
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}
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void __init fork_init(unsigned long mempages)
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{
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#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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#ifndef ARCH_MIN_TASKALIGN
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#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
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#endif
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/* create a slab on which task_structs can be allocated */
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task_struct_cachep =
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kmem_cache_create("task_struct", sizeof(struct task_struct),
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ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
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#endif
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/*
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* The default maximum number of threads is set to a safe
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* value: the thread structures can take up at most half
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* of memory.
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*/
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max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
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/*
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* we need to allow at least 20 threads to boot a system
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*/
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if(max_threads < 20)
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max_threads = 20;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
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init_task.signal->rlim[RLIMIT_SIGPENDING] =
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init_task.signal->rlim[RLIMIT_NPROC];
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}
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static struct task_struct *dup_task_struct(struct task_struct *orig)
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{
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struct task_struct *tsk;
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struct thread_info *ti;
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prepare_to_copy(orig);
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tsk = alloc_task_struct();
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if (!tsk)
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return NULL;
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ti = alloc_thread_info(tsk);
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if (!ti) {
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free_task_struct(tsk);
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return NULL;
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}
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*tsk = *orig;
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tsk->thread_info = ti;
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setup_thread_stack(tsk, orig);
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#ifdef CONFIG_CC_STACKPROTECTOR
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tsk->stack_canary = get_random_int();
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#endif
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/* One for us, one for whoever does the "release_task()" (usually parent) */
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atomic_set(&tsk->usage,2);
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atomic_set(&tsk->fs_excl, 0);
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#ifdef CONFIG_BLK_DEV_IO_TRACE
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tsk->btrace_seq = 0;
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#endif
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tsk->splice_pipe = NULL;
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return tsk;
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}
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#ifdef CONFIG_MMU
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static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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struct vm_area_struct *mpnt, *tmp, **pprev;
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struct rb_node **rb_link, *rb_parent;
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int retval;
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unsigned long charge;
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struct mempolicy *pol;
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down_write(&oldmm->mmap_sem);
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flush_cache_mm(oldmm);
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/*
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* Not linked in yet - no deadlock potential:
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*/
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down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
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mm->locked_vm = 0;
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mm->mmap = NULL;
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mm->mmap_cache = NULL;
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mm->free_area_cache = oldmm->mmap_base;
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mm->cached_hole_size = ~0UL;
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mm->map_count = 0;
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cpus_clear(mm->cpu_vm_mask);
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mm->mm_rb = RB_ROOT;
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rb_link = &mm->mm_rb.rb_node;
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rb_parent = NULL;
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pprev = &mm->mmap;
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for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
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struct file *file;
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if (mpnt->vm_flags & VM_DONTCOPY) {
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long pages = vma_pages(mpnt);
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mm->total_vm -= pages;
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vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
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-pages);
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continue;
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}
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charge = 0;
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if (mpnt->vm_flags & VM_ACCOUNT) {
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unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
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if (security_vm_enough_memory(len))
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goto fail_nomem;
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charge = len;
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}
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tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
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if (!tmp)
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goto fail_nomem;
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*tmp = *mpnt;
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pol = mpol_copy(vma_policy(mpnt));
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retval = PTR_ERR(pol);
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if (IS_ERR(pol))
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goto fail_nomem_policy;
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vma_set_policy(tmp, pol);
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tmp->vm_flags &= ~VM_LOCKED;
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tmp->vm_mm = mm;
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tmp->vm_next = NULL;
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anon_vma_link(tmp);
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file = tmp->vm_file;
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if (file) {
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struct inode *inode = file->f_dentry->d_inode;
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get_file(file);
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if (tmp->vm_flags & VM_DENYWRITE)
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atomic_dec(&inode->i_writecount);
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/* insert tmp into the share list, just after mpnt */
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spin_lock(&file->f_mapping->i_mmap_lock);
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tmp->vm_truncate_count = mpnt->vm_truncate_count;
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flush_dcache_mmap_lock(file->f_mapping);
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vma_prio_tree_add(tmp, mpnt);
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flush_dcache_mmap_unlock(file->f_mapping);
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spin_unlock(&file->f_mapping->i_mmap_lock);
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}
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/*
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* Link in the new vma and copy the page table entries.
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*/
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*pprev = tmp;
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pprev = &tmp->vm_next;
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__vma_link_rb(mm, tmp, rb_link, rb_parent);
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rb_link = &tmp->vm_rb.rb_right;
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rb_parent = &tmp->vm_rb;
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mm->map_count++;
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retval = copy_page_range(mm, oldmm, mpnt);
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if (tmp->vm_ops && tmp->vm_ops->open)
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tmp->vm_ops->open(tmp);
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if (retval)
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goto out;
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}
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retval = 0;
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out:
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up_write(&mm->mmap_sem);
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flush_tlb_mm(oldmm);
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up_write(&oldmm->mmap_sem);
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return retval;
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fail_nomem_policy:
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kmem_cache_free(vm_area_cachep, tmp);
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fail_nomem:
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retval = -ENOMEM;
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vm_unacct_memory(charge);
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goto out;
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}
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static inline int mm_alloc_pgd(struct mm_struct * mm)
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{
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mm->pgd = pgd_alloc(mm);
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if (unlikely(!mm->pgd))
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return -ENOMEM;
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return 0;
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}
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static inline void mm_free_pgd(struct mm_struct * mm)
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{
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pgd_free(mm->pgd);
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}
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#else
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#define dup_mmap(mm, oldmm) (0)
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#define mm_alloc_pgd(mm) (0)
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#define mm_free_pgd(mm)
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#endif /* CONFIG_MMU */
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
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#define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
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#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
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#include <linux/init_task.h>
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static struct mm_struct * mm_init(struct mm_struct * mm)
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{
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atomic_set(&mm->mm_users, 1);
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atomic_set(&mm->mm_count, 1);
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init_rwsem(&mm->mmap_sem);
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INIT_LIST_HEAD(&mm->mmlist);
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mm->core_waiters = 0;
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mm->nr_ptes = 0;
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set_mm_counter(mm, file_rss, 0);
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set_mm_counter(mm, anon_rss, 0);
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spin_lock_init(&mm->page_table_lock);
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rwlock_init(&mm->ioctx_list_lock);
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mm->ioctx_list = NULL;
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mm->free_area_cache = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = ~0UL;
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|
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if (likely(!mm_alloc_pgd(mm))) {
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mm->def_flags = 0;
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return mm;
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|
}
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free_mm(mm);
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return NULL;
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}
|
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|
|
/*
|
|
* Allocate and initialize an mm_struct.
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*/
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struct mm_struct * mm_alloc(void)
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{
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struct mm_struct * mm;
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|
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mm = allocate_mm();
|
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if (mm) {
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memset(mm, 0, sizeof(*mm));
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mm = mm_init(mm);
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}
|
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return mm;
|
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}
|
|
|
|
/*
|
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* Called when the last reference to the mm
|
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* is dropped: either by a lazy thread or by
|
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* mmput. Free the page directory and the mm.
|
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*/
|
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void fastcall __mmdrop(struct mm_struct *mm)
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{
|
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BUG_ON(mm == &init_mm);
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mm_free_pgd(mm);
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destroy_context(mm);
|
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free_mm(mm);
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}
|
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|
|
/*
|
|
* Decrement the use count and release all resources for an mm.
|
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*/
|
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void mmput(struct mm_struct *mm)
|
|
{
|
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might_sleep();
|
|
|
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if (atomic_dec_and_test(&mm->mm_users)) {
|
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exit_aio(mm);
|
|
exit_mmap(mm);
|
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if (!list_empty(&mm->mmlist)) {
|
|
spin_lock(&mmlist_lock);
|
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list_del(&mm->mmlist);
|
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spin_unlock(&mmlist_lock);
|
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}
|
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put_swap_token(mm);
|
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mmdrop(mm);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(mmput);
|
|
|
|
/**
|
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* get_task_mm - acquire a reference to the task's mm
|
|
*
|
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* Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (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
|
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* bumping up the use count. User must release the mm via mmput()
|
|
* after use. Typically used by /proc and ptrace.
|
|
*/
|
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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_BORROWED_MM)
|
|
mm = NULL;
|
|
else
|
|
atomic_inc(&mm->mm_users);
|
|
}
|
|
task_unlock(task);
|
|
return mm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_task_mm);
|
|
|
|
/* Please note the differences between mmput and mm_release.
|
|
* mmput is called whenever we stop holding onto a mm_struct,
|
|
* error success whatever.
|
|
*
|
|
* mm_release is called after a mm_struct has been removed
|
|
* from the current process.
|
|
*
|
|
* This difference is important for error handling, when we
|
|
* only half set up a mm_struct for a new process and need to restore
|
|
* the old one. Because we mmput the new mm_struct before
|
|
* restoring the old one. . .
|
|
* Eric Biederman 10 January 1998
|
|
*/
|
|
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
|
|
{
|
|
struct completion *vfork_done = tsk->vfork_done;
|
|
|
|
/* Get rid of any cached register state */
|
|
deactivate_mm(tsk, mm);
|
|
|
|
/* notify parent sleeping on vfork() */
|
|
if (vfork_done) {
|
|
tsk->vfork_done = NULL;
|
|
complete(vfork_done);
|
|
}
|
|
if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
|
|
u32 __user * tidptr = tsk->clear_child_tid;
|
|
tsk->clear_child_tid = NULL;
|
|
|
|
/*
|
|
* We don't check the error code - if userspace has
|
|
* not set up a proper pointer then tough luck.
|
|
*/
|
|
put_user(0, tidptr);
|
|
sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new mm structure and copy contents from the
|
|
* mm structure of the passed in task structure.
|
|
*/
|
|
static struct mm_struct *dup_mm(struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm = current->mm;
|
|
int err;
|
|
|
|
if (!oldmm)
|
|
return NULL;
|
|
|
|
mm = allocate_mm();
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
memcpy(mm, oldmm, sizeof(*mm));
|
|
|
|
if (!mm_init(mm))
|
|
goto fail_nomem;
|
|
|
|
if (init_new_context(tsk, mm))
|
|
goto fail_nocontext;
|
|
|
|
err = dup_mmap(mm, oldmm);
|
|
if (err)
|
|
goto free_pt;
|
|
|
|
mm->hiwater_rss = get_mm_rss(mm);
|
|
mm->hiwater_vm = mm->total_vm;
|
|
|
|
return mm;
|
|
|
|
free_pt:
|
|
mmput(mm);
|
|
|
|
fail_nomem:
|
|
return NULL;
|
|
|
|
fail_nocontext:
|
|
/*
|
|
* If init_new_context() failed, we cannot use mmput() to free the mm
|
|
* because it calls destroy_context()
|
|
*/
|
|
mm_free_pgd(mm);
|
|
free_mm(mm);
|
|
return NULL;
|
|
}
|
|
|
|
static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct mm_struct * mm, *oldmm;
|
|
int retval;
|
|
|
|
tsk->min_flt = tsk->maj_flt = 0;
|
|
tsk->nvcsw = tsk->nivcsw = 0;
|
|
|
|
tsk->mm = NULL;
|
|
tsk->active_mm = NULL;
|
|
|
|
/*
|
|
* Are we cloning a kernel thread?
|
|
*
|
|
* We need to steal a active VM for that..
|
|
*/
|
|
oldmm = current->mm;
|
|
if (!oldmm)
|
|
return 0;
|
|
|
|
if (clone_flags & CLONE_VM) {
|
|
atomic_inc(&oldmm->mm_users);
|
|
mm = oldmm;
|
|
goto good_mm;
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
mm = dup_mm(tsk);
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
good_mm:
|
|
tsk->mm = mm;
|
|
tsk->active_mm = mm;
|
|
return 0;
|
|
|
|
fail_nomem:
|
|
return retval;
|
|
}
|
|
|
|
static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
|
|
{
|
|
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
|
|
/* We don't need to lock fs - think why ;-) */
|
|
if (fs) {
|
|
atomic_set(&fs->count, 1);
|
|
rwlock_init(&fs->lock);
|
|
fs->umask = old->umask;
|
|
read_lock(&old->lock);
|
|
fs->rootmnt = mntget(old->rootmnt);
|
|
fs->root = dget(old->root);
|
|
fs->pwdmnt = mntget(old->pwdmnt);
|
|
fs->pwd = dget(old->pwd);
|
|
if (old->altroot) {
|
|
fs->altrootmnt = mntget(old->altrootmnt);
|
|
fs->altroot = dget(old->altroot);
|
|
} else {
|
|
fs->altrootmnt = NULL;
|
|
fs->altroot = NULL;
|
|
}
|
|
read_unlock(&old->lock);
|
|
}
|
|
return fs;
|
|
}
|
|
|
|
struct fs_struct *copy_fs_struct(struct fs_struct *old)
|
|
{
|
|
return __copy_fs_struct(old);
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(copy_fs_struct);
|
|
|
|
static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
if (clone_flags & CLONE_FS) {
|
|
atomic_inc(¤t->fs->count);
|
|
return 0;
|
|
}
|
|
tsk->fs = __copy_fs_struct(current->fs);
|
|
if (!tsk->fs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static int count_open_files(struct fdtable *fdt)
|
|
{
|
|
int size = fdt->max_fdset;
|
|
int i;
|
|
|
|
/* Find the last open fd */
|
|
for (i = size/(8*sizeof(long)); i > 0; ) {
|
|
if (fdt->open_fds->fds_bits[--i])
|
|
break;
|
|
}
|
|
i = (i+1) * 8 * sizeof(long);
|
|
return i;
|
|
}
|
|
|
|
static struct files_struct *alloc_files(void)
|
|
{
|
|
struct files_struct *newf;
|
|
struct fdtable *fdt;
|
|
|
|
newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
atomic_set(&newf->count, 1);
|
|
|
|
spin_lock_init(&newf->file_lock);
|
|
newf->next_fd = 0;
|
|
fdt = &newf->fdtab;
|
|
fdt->max_fds = NR_OPEN_DEFAULT;
|
|
fdt->max_fdset = EMBEDDED_FD_SET_SIZE;
|
|
fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
|
|
fdt->open_fds = (fd_set *)&newf->open_fds_init;
|
|
fdt->fd = &newf->fd_array[0];
|
|
INIT_RCU_HEAD(&fdt->rcu);
|
|
fdt->free_files = NULL;
|
|
fdt->next = NULL;
|
|
rcu_assign_pointer(newf->fdt, fdt);
|
|
out:
|
|
return newf;
|
|
}
|
|
|
|
/*
|
|
* Allocate a new files structure and copy contents from the
|
|
* passed in files structure.
|
|
* errorp will be valid only when the returned files_struct is NULL.
|
|
*/
|
|
static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
|
|
{
|
|
struct files_struct *newf;
|
|
struct file **old_fds, **new_fds;
|
|
int open_files, size, i, expand;
|
|
struct fdtable *old_fdt, *new_fdt;
|
|
|
|
*errorp = -ENOMEM;
|
|
newf = alloc_files();
|
|
if (!newf)
|
|
goto out;
|
|
|
|
spin_lock(&oldf->file_lock);
|
|
old_fdt = files_fdtable(oldf);
|
|
new_fdt = files_fdtable(newf);
|
|
size = old_fdt->max_fdset;
|
|
open_files = count_open_files(old_fdt);
|
|
expand = 0;
|
|
|
|
/*
|
|
* Check whether we need to allocate a larger fd array or fd set.
|
|
* Note: we're not a clone task, so the open count won't change.
|
|
*/
|
|
if (open_files > new_fdt->max_fdset) {
|
|
new_fdt->max_fdset = 0;
|
|
expand = 1;
|
|
}
|
|
if (open_files > new_fdt->max_fds) {
|
|
new_fdt->max_fds = 0;
|
|
expand = 1;
|
|
}
|
|
|
|
/* if the old fdset gets grown now, we'll only copy up to "size" fds */
|
|
if (expand) {
|
|
spin_unlock(&oldf->file_lock);
|
|
spin_lock(&newf->file_lock);
|
|
*errorp = expand_files(newf, open_files-1);
|
|
spin_unlock(&newf->file_lock);
|
|
if (*errorp < 0)
|
|
goto out_release;
|
|
new_fdt = files_fdtable(newf);
|
|
/*
|
|
* Reacquire the oldf lock and a pointer to its fd table
|
|
* who knows it may have a new bigger fd table. We need
|
|
* the latest pointer.
|
|
*/
|
|
spin_lock(&oldf->file_lock);
|
|
old_fdt = files_fdtable(oldf);
|
|
}
|
|
|
|
old_fds = old_fdt->fd;
|
|
new_fds = new_fdt->fd;
|
|
|
|
memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
|
|
memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
|
|
|
|
for (i = open_files; i != 0; i--) {
|
|
struct file *f = *old_fds++;
|
|
if (f) {
|
|
get_file(f);
|
|
} else {
|
|
/*
|
|
* The fd may be claimed in the fd bitmap but not yet
|
|
* instantiated in the files array if a sibling thread
|
|
* is partway through open(). So make sure that this
|
|
* fd is available to the new process.
|
|
*/
|
|
FD_CLR(open_files - i, new_fdt->open_fds);
|
|
}
|
|
rcu_assign_pointer(*new_fds++, f);
|
|
}
|
|
spin_unlock(&oldf->file_lock);
|
|
|
|
/* compute the remainder to be cleared */
|
|
size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
|
|
|
|
/* This is long word aligned thus could use a optimized version */
|
|
memset(new_fds, 0, size);
|
|
|
|
if (new_fdt->max_fdset > open_files) {
|
|
int left = (new_fdt->max_fdset-open_files)/8;
|
|
int start = open_files / (8 * sizeof(unsigned long));
|
|
|
|
memset(&new_fdt->open_fds->fds_bits[start], 0, left);
|
|
memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
|
|
}
|
|
|
|
out:
|
|
return newf;
|
|
|
|
out_release:
|
|
free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
|
|
free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
|
|
free_fd_array(new_fdt->fd, new_fdt->max_fds);
|
|
kmem_cache_free(files_cachep, newf);
|
|
return NULL;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Note: we may be using current for both targets (See exec.c)
|
|
* This works because we cache current->files (old) as oldf. Don't
|
|
* break this.
|
|
*/
|
|
tsk->files = NULL;
|
|
newf = dup_fd(oldf, &error);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
tsk->files = newf;
|
|
error = 0;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* 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 files_struct *files = current->files;
|
|
int rc;
|
|
|
|
BUG_ON(!files);
|
|
|
|
/* This can race but the race causes us to copy when we don't
|
|
need to and drop the copy */
|
|
if(atomic_read(&files->count) == 1)
|
|
{
|
|
atomic_inc(&files->count);
|
|
return 0;
|
|
}
|
|
rc = copy_files(0, current);
|
|
if(rc)
|
|
current->files = files;
|
|
return rc;
|
|
}
|
|
|
|
EXPORT_SYMBOL(unshare_files);
|
|
|
|
static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct sighand_struct *sig;
|
|
|
|
if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
|
|
atomic_inc(¤t->sighand->count);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
|
rcu_assign_pointer(tsk->sighand, sig);
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
atomic_set(&sig->count, 1);
|
|
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_sighand(struct sighand_struct *sighand)
|
|
{
|
|
if (atomic_dec_and_test(&sighand->count))
|
|
kmem_cache_free(sighand_cachep, sighand);
|
|
}
|
|
|
|
static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
|
|
{
|
|
struct signal_struct *sig;
|
|
int ret;
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
atomic_inc(¤t->signal->count);
|
|
atomic_inc(¤t->signal->live);
|
|
taskstats_tgid_alloc(current);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
|
|
tsk->signal = sig;
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
|
|
ret = copy_thread_group_keys(tsk);
|
|
if (ret < 0) {
|
|
kmem_cache_free(signal_cachep, sig);
|
|
return ret;
|
|
}
|
|
|
|
atomic_set(&sig->count, 1);
|
|
atomic_set(&sig->live, 1);
|
|
init_waitqueue_head(&sig->wait_chldexit);
|
|
sig->flags = 0;
|
|
sig->group_exit_code = 0;
|
|
sig->group_exit_task = NULL;
|
|
sig->group_stop_count = 0;
|
|
sig->curr_target = NULL;
|
|
init_sigpending(&sig->shared_pending);
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
|
|
sig->it_real_incr.tv64 = 0;
|
|
sig->real_timer.function = it_real_fn;
|
|
sig->tsk = tsk;
|
|
|
|
sig->it_virt_expires = cputime_zero;
|
|
sig->it_virt_incr = cputime_zero;
|
|
sig->it_prof_expires = cputime_zero;
|
|
sig->it_prof_incr = cputime_zero;
|
|
|
|
sig->leader = 0; /* session leadership doesn't inherit */
|
|
sig->tty_old_pgrp = 0;
|
|
|
|
sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
|
|
sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
|
|
sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
|
|
sig->sched_time = 0;
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
taskstats_tgid_init(sig);
|
|
|
|
task_lock(current->group_leader);
|
|
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
|
task_unlock(current->group_leader);
|
|
|
|
if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
|
|
/*
|
|
* New sole thread in the process gets an expiry time
|
|
* of the whole CPU time limit.
|
|
*/
|
|
tsk->it_prof_expires =
|
|
secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
}
|
|
acct_init_pacct(&sig->pacct);
|
|
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_signal(struct signal_struct *sig)
|
|
{
|
|
exit_thread_group_keys(sig);
|
|
kmem_cache_free(signal_cachep, sig);
|
|
}
|
|
|
|
static inline void cleanup_signal(struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig = tsk->signal;
|
|
|
|
atomic_dec(&sig->live);
|
|
|
|
if (atomic_dec_and_test(&sig->count))
|
|
__cleanup_signal(sig);
|
|
}
|
|
|
|
static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
unsigned long new_flags = p->flags;
|
|
|
|
new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
|
|
new_flags |= PF_FORKNOEXEC;
|
|
if (!(clone_flags & CLONE_PTRACE))
|
|
p->ptrace = 0;
|
|
p->flags = new_flags;
|
|
}
|
|
|
|
asmlinkage long sys_set_tid_address(int __user *tidptr)
|
|
{
|
|
current->clear_child_tid = tidptr;
|
|
|
|
return current->pid;
|
|
}
|
|
|
|
static inline void rt_mutex_init_task(struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
spin_lock_init(&p->pi_lock);
|
|
plist_head_init(&p->pi_waiters, &p->pi_lock);
|
|
p->pi_blocked_on = NULL;
|
|
#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 struct task_struct *copy_process(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr,
|
|
int pid)
|
|
{
|
|
int retval;
|
|
struct task_struct *p = NULL;
|
|
|
|
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|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);
|
|
|
|
retval = security_task_create(clone_flags);
|
|
if (retval)
|
|
goto fork_out;
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
rt_mutex_init_task(p);
|
|
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
|
|
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
|
#endif
|
|
retval = -EAGAIN;
|
|
if (atomic_read(&p->user->processes) >=
|
|
p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
|
|
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
|
|
p->user != &root_user)
|
|
goto bad_fork_free;
|
|
}
|
|
|
|
atomic_inc(&p->user->__count);
|
|
atomic_inc(&p->user->processes);
|
|
get_group_info(p->group_info);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (nr_threads >= max_threads)
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (!try_module_get(task_thread_info(p)->exec_domain->module))
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (p->binfmt && !try_module_get(p->binfmt->module))
|
|
goto bad_fork_cleanup_put_domain;
|
|
|
|
p->did_exec = 0;
|
|
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
|
|
copy_flags(clone_flags, p);
|
|
p->pid = pid;
|
|
retval = -EFAULT;
|
|
if (clone_flags & CLONE_PARENT_SETTID)
|
|
if (put_user(p->pid, parent_tidptr))
|
|
goto bad_fork_cleanup_delays_binfmt;
|
|
|
|
INIT_LIST_HEAD(&p->children);
|
|
INIT_LIST_HEAD(&p->sibling);
|
|
p->vfork_done = NULL;
|
|
spin_lock_init(&p->alloc_lock);
|
|
|
|
clear_tsk_thread_flag(p, TIF_SIGPENDING);
|
|
init_sigpending(&p->pending);
|
|
|
|
p->utime = cputime_zero;
|
|
p->stime = cputime_zero;
|
|
p->sched_time = 0;
|
|
p->rchar = 0; /* I/O counter: bytes read */
|
|
p->wchar = 0; /* I/O counter: bytes written */
|
|
p->syscr = 0; /* I/O counter: read syscalls */
|
|
p->syscw = 0; /* I/O counter: write syscalls */
|
|
acct_clear_integrals(p);
|
|
|
|
p->it_virt_expires = cputime_zero;
|
|
p->it_prof_expires = cputime_zero;
|
|
p->it_sched_expires = 0;
|
|
INIT_LIST_HEAD(&p->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&p->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&p->cpu_timers[2]);
|
|
|
|
p->lock_depth = -1; /* -1 = no lock */
|
|
do_posix_clock_monotonic_gettime(&p->start_time);
|
|
p->security = NULL;
|
|
p->io_context = NULL;
|
|
p->io_wait = NULL;
|
|
p->audit_context = NULL;
|
|
cpuset_fork(p);
|
|
#ifdef CONFIG_NUMA
|
|
p->mempolicy = mpol_copy(p->mempolicy);
|
|
if (IS_ERR(p->mempolicy)) {
|
|
retval = PTR_ERR(p->mempolicy);
|
|
p->mempolicy = NULL;
|
|
goto bad_fork_cleanup_cpuset;
|
|
}
|
|
mpol_fix_fork_child_flag(p);
|
|
#endif
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
p->irq_events = 0;
|
|
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
|
|
p->hardirqs_enabled = 1;
|
|
#else
|
|
p->hardirqs_enabled = 0;
|
|
#endif
|
|
p->hardirq_enable_ip = 0;
|
|
p->hardirq_enable_event = 0;
|
|
p->hardirq_disable_ip = _THIS_IP_;
|
|
p->hardirq_disable_event = 0;
|
|
p->softirqs_enabled = 1;
|
|
p->softirq_enable_ip = _THIS_IP_;
|
|
p->softirq_enable_event = 0;
|
|
p->softirq_disable_ip = 0;
|
|
p->softirq_disable_event = 0;
|
|
p->hardirq_context = 0;
|
|
p->softirq_context = 0;
|
|
#endif
|
|
#ifdef CONFIG_LOCKDEP
|
|
p->lockdep_depth = 0; /* no locks held yet */
|
|
p->curr_chain_key = 0;
|
|
p->lockdep_recursion = 0;
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_MUTEXES
|
|
p->blocked_on = NULL; /* not blocked yet */
|
|
#endif
|
|
|
|
p->tgid = p->pid;
|
|
if (clone_flags & CLONE_THREAD)
|
|
p->tgid = current->tgid;
|
|
|
|
if ((retval = security_task_alloc(p)))
|
|
goto bad_fork_cleanup_policy;
|
|
if ((retval = audit_alloc(p)))
|
|
goto bad_fork_cleanup_security;
|
|
/* copy all the process information */
|
|
if ((retval = copy_semundo(clone_flags, p)))
|
|
goto bad_fork_cleanup_audit;
|
|
if ((retval = copy_files(clone_flags, p)))
|
|
goto bad_fork_cleanup_semundo;
|
|
if ((retval = copy_fs(clone_flags, p)))
|
|
goto bad_fork_cleanup_files;
|
|
if ((retval = copy_sighand(clone_flags, p)))
|
|
goto bad_fork_cleanup_fs;
|
|
if ((retval = copy_signal(clone_flags, p)))
|
|
goto bad_fork_cleanup_sighand;
|
|
if ((retval = copy_mm(clone_flags, p)))
|
|
goto bad_fork_cleanup_signal;
|
|
if ((retval = copy_keys(clone_flags, p)))
|
|
goto bad_fork_cleanup_mm;
|
|
if ((retval = copy_namespaces(clone_flags, p)))
|
|
goto bad_fork_cleanup_keys;
|
|
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
|
|
if (retval)
|
|
goto bad_fork_cleanup_namespaces;
|
|
|
|
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
|
|
/*
|
|
* Clear TID on mm_release()?
|
|
*/
|
|
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
|
|
p->robust_list = NULL;
|
|
#ifdef CONFIG_COMPAT
|
|
p->compat_robust_list = NULL;
|
|
#endif
|
|
INIT_LIST_HEAD(&p->pi_state_list);
|
|
p->pi_state_cache = NULL;
|
|
|
|
/*
|
|
* sigaltstack should be cleared when sharing the same VM
|
|
*/
|
|
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
|
p->sas_ss_sp = p->sas_ss_size = 0;
|
|
|
|
/*
|
|
* Syscall tracing should be turned off in the child regardless
|
|
* of CLONE_PTRACE.
|
|
*/
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
|
|
#ifdef TIF_SYSCALL_EMU
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
|
|
#endif
|
|
|
|
/* Our parent execution domain becomes current domain
|
|
These must match for thread signalling to apply */
|
|
p->parent_exec_id = p->self_exec_id;
|
|
|
|
/* ok, now we should be set up.. */
|
|
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
|
|
p->pdeath_signal = 0;
|
|
p->exit_state = 0;
|
|
|
|
/*
|
|
* Ok, make it visible to the rest of the system.
|
|
* We dont wake it up yet.
|
|
*/
|
|
p->group_leader = p;
|
|
INIT_LIST_HEAD(&p->thread_group);
|
|
INIT_LIST_HEAD(&p->ptrace_children);
|
|
INIT_LIST_HEAD(&p->ptrace_list);
|
|
|
|
/* Perform scheduler related setup. Assign this task to a CPU. */
|
|
sched_fork(p, clone_flags);
|
|
|
|
/* Need tasklist lock for parent etc handling! */
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
/* for sys_ioprio_set(IOPRIO_WHO_PGRP) */
|
|
p->ioprio = current->ioprio;
|
|
|
|
/*
|
|
* The task hasn't been attached yet, so its cpus_allowed mask will
|
|
* not be changed, nor will its assigned CPU.
|
|
*
|
|
* The cpus_allowed mask of the parent may have changed after it was
|
|
* copied first time - so re-copy it here, then check the child's CPU
|
|
* to ensure it is on a valid CPU (and if not, just force it back to
|
|
* parent's CPU). This avoids alot of nasty races.
|
|
*/
|
|
p->cpus_allowed = current->cpus_allowed;
|
|
if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
|
|
!cpu_online(task_cpu(p))))
|
|
set_task_cpu(p, smp_processor_id());
|
|
|
|
/* CLONE_PARENT re-uses the old parent */
|
|
if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
|
|
p->real_parent = current->real_parent;
|
|
else
|
|
p->real_parent = current;
|
|
p->parent = p->real_parent;
|
|
|
|
spin_lock(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Process group and session signals need to be delivered to just the
|
|
* parent before the fork or both the parent and the child after the
|
|
* fork. Restart if a signal comes in before we add the new process to
|
|
* it's process group.
|
|
* A fatal signal pending means that current will exit, so the new
|
|
* thread can't slip out of an OOM kill (or normal SIGKILL).
|
|
*/
|
|
recalc_sigpending();
|
|
if (signal_pending(current)) {
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_cleanup_namespaces;
|
|
}
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
p->group_leader = current->group_leader;
|
|
list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
|
|
|
|
if (!cputime_eq(current->signal->it_virt_expires,
|
|
cputime_zero) ||
|
|
!cputime_eq(current->signal->it_prof_expires,
|
|
cputime_zero) ||
|
|
current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
|
|
!list_empty(¤t->signal->cpu_timers[0]) ||
|
|
!list_empty(¤t->signal->cpu_timers[1]) ||
|
|
!list_empty(¤t->signal->cpu_timers[2])) {
|
|
/*
|
|
* Have child wake up on its first tick to check
|
|
* for process CPU timers.
|
|
*/
|
|
p->it_prof_expires = jiffies_to_cputime(1);
|
|
}
|
|
}
|
|
|
|
if (likely(p->pid)) {
|
|
add_parent(p);
|
|
if (unlikely(p->ptrace & PT_PTRACED))
|
|
__ptrace_link(p, current->parent);
|
|
|
|
if (thread_group_leader(p)) {
|
|
p->signal->tty = current->signal->tty;
|
|
p->signal->pgrp = process_group(current);
|
|
p->signal->session = current->signal->session;
|
|
attach_pid(p, PIDTYPE_PGID, process_group(p));
|
|
attach_pid(p, PIDTYPE_SID, p->signal->session);
|
|
|
|
list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
|
__get_cpu_var(process_counts)++;
|
|
}
|
|
attach_pid(p, PIDTYPE_PID, p->pid);
|
|
nr_threads++;
|
|
}
|
|
|
|
total_forks++;
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
proc_fork_connector(p);
|
|
return p;
|
|
|
|
bad_fork_cleanup_namespaces:
|
|
exit_task_namespaces(p);
|
|
bad_fork_cleanup_keys:
|
|
exit_keys(p);
|
|
bad_fork_cleanup_mm:
|
|
if (p->mm)
|
|
mmput(p->mm);
|
|
bad_fork_cleanup_signal:
|
|
cleanup_signal(p);
|
|
bad_fork_cleanup_sighand:
|
|
__cleanup_sighand(p->sighand);
|
|
bad_fork_cleanup_fs:
|
|
exit_fs(p); /* blocking */
|
|
bad_fork_cleanup_files:
|
|
exit_files(p); /* blocking */
|
|
bad_fork_cleanup_semundo:
|
|
exit_sem(p);
|
|
bad_fork_cleanup_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_security:
|
|
security_task_free(p);
|
|
bad_fork_cleanup_policy:
|
|
#ifdef CONFIG_NUMA
|
|
mpol_free(p->mempolicy);
|
|
bad_fork_cleanup_cpuset:
|
|
#endif
|
|
cpuset_exit(p);
|
|
bad_fork_cleanup_delays_binfmt:
|
|
delayacct_tsk_free(p);
|
|
if (p->binfmt)
|
|
module_put(p->binfmt->module);
|
|
bad_fork_cleanup_put_domain:
|
|
module_put(task_thread_info(p)->exec_domain->module);
|
|
bad_fork_cleanup_count:
|
|
put_group_info(p->group_info);
|
|
atomic_dec(&p->user->processes);
|
|
free_uid(p->user);
|
|
bad_fork_free:
|
|
free_task(p);
|
|
fork_out:
|
|
return ERR_PTR(retval);
|
|
}
|
|
|
|
struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
|
|
{
|
|
memset(regs, 0, sizeof(struct pt_regs));
|
|
return regs;
|
|
}
|
|
|
|
struct task_struct * __devinit fork_idle(int cpu)
|
|
{
|
|
struct task_struct *task;
|
|
struct pt_regs regs;
|
|
|
|
task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0);
|
|
if (!task)
|
|
return ERR_PTR(-ENOMEM);
|
|
init_idle(task, cpu);
|
|
|
|
return task;
|
|
}
|
|
|
|
static inline int fork_traceflag (unsigned clone_flags)
|
|
{
|
|
if (clone_flags & CLONE_UNTRACED)
|
|
return 0;
|
|
else if (clone_flags & CLONE_VFORK) {
|
|
if (current->ptrace & PT_TRACE_VFORK)
|
|
return PTRACE_EVENT_VFORK;
|
|
} else if ((clone_flags & CSIGNAL) != SIGCHLD) {
|
|
if (current->ptrace & PT_TRACE_CLONE)
|
|
return PTRACE_EVENT_CLONE;
|
|
} else if (current->ptrace & PT_TRACE_FORK)
|
|
return PTRACE_EVENT_FORK;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Ok, this is the main fork-routine.
|
|
*
|
|
* It copies the process, and if successful kick-starts
|
|
* it and waits for it to finish using the VM if required.
|
|
*/
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
struct task_struct *p;
|
|
int trace = 0;
|
|
struct pid *pid = alloc_pid();
|
|
long nr;
|
|
|
|
if (!pid)
|
|
return -EAGAIN;
|
|
nr = pid->nr;
|
|
if (unlikely(current->ptrace)) {
|
|
trace = fork_traceflag (clone_flags);
|
|
if (trace)
|
|
clone_flags |= CLONE_PTRACE;
|
|
}
|
|
|
|
p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, nr);
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
if (!IS_ERR(p)) {
|
|
struct completion vfork;
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
p->vfork_done = &vfork;
|
|
init_completion(&vfork);
|
|
}
|
|
|
|
if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
|
|
/*
|
|
* We'll start up with an immediate SIGSTOP.
|
|
*/
|
|
sigaddset(&p->pending.signal, SIGSTOP);
|
|
set_tsk_thread_flag(p, TIF_SIGPENDING);
|
|
}
|
|
|
|
if (!(clone_flags & CLONE_STOPPED))
|
|
wake_up_new_task(p, clone_flags);
|
|
else
|
|
p->state = TASK_STOPPED;
|
|
|
|
if (unlikely (trace)) {
|
|
current->ptrace_message = nr;
|
|
ptrace_notify ((trace << 8) | SIGTRAP);
|
|
}
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
wait_for_completion(&vfork);
|
|
if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
|
|
current->ptrace_message = nr;
|
|
ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
|
|
}
|
|
}
|
|
} else {
|
|
free_pid(pid);
|
|
nr = PTR_ERR(p);
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
|
#define ARCH_MIN_MMSTRUCT_ALIGN 0
|
|
#endif
|
|
|
|
static void sighand_ctor(void *data, kmem_cache_t *cachep, unsigned long flags)
|
|
{
|
|
struct sighand_struct *sighand = data;
|
|
|
|
if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
|
|
SLAB_CTOR_CONSTRUCTOR)
|
|
spin_lock_init(&sighand->siglock);
|
|
}
|
|
|
|
void __init proc_caches_init(void)
|
|
{
|
|
sighand_cachep = kmem_cache_create("sighand_cache",
|
|
sizeof(struct sighand_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
|
|
sighand_ctor, NULL);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
|
|
vm_area_cachep = kmem_cache_create("vm_area_struct",
|
|
sizeof(struct vm_area_struct), 0,
|
|
SLAB_PANIC, NULL, NULL);
|
|
mm_cachep = kmem_cache_create("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
|
|
}
|
|
|
|
|
|
/*
|
|
* Check constraints on flags passed to the unshare system call and
|
|
* force unsharing of additional process context as appropriate.
|
|
*/
|
|
static inline void check_unshare_flags(unsigned long *flags_ptr)
|
|
{
|
|
/*
|
|
* If unsharing a thread from a thread group, must also
|
|
* unshare vm.
|
|
*/
|
|
if (*flags_ptr & CLONE_THREAD)
|
|
*flags_ptr |= CLONE_VM;
|
|
|
|
/*
|
|
* If unsharing vm, must also unshare signal handlers.
|
|
*/
|
|
if (*flags_ptr & CLONE_VM)
|
|
*flags_ptr |= CLONE_SIGHAND;
|
|
|
|
/*
|
|
* If unsharing signal handlers and the task was created
|
|
* using CLONE_THREAD, then must unshare the thread
|
|
*/
|
|
if ((*flags_ptr & CLONE_SIGHAND) &&
|
|
(atomic_read(¤t->signal->count) > 1))
|
|
*flags_ptr |= CLONE_THREAD;
|
|
|
|
/*
|
|
* If unsharing namespace, must also unshare filesystem information.
|
|
*/
|
|
if (*flags_ptr & CLONE_NEWNS)
|
|
*flags_ptr |= CLONE_FS;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of tasks created with CLONE_THREAD is not supported yet
|
|
*/
|
|
static int unshare_thread(unsigned long unshare_flags)
|
|
{
|
|
if (unshare_flags & CLONE_THREAD)
|
|
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 && atomic_read(&fs->count) > 1)) {
|
|
*new_fsp = __copy_fs_struct(current->fs);
|
|
if (!*new_fsp)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare the namespace structure if it is being shared
|
|
*/
|
|
static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp, struct fs_struct *new_fs)
|
|
{
|
|
struct namespace *ns = current->nsproxy->namespace;
|
|
|
|
if ((unshare_flags & CLONE_NEWNS) && ns) {
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
*new_nsp = dup_namespace(current, new_fs ? new_fs : current->fs);
|
|
if (!*new_nsp)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of sighand for tasks created with CLONE_SIGHAND is not
|
|
* supported yet
|
|
*/
|
|
static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
|
|
{
|
|
struct sighand_struct *sigh = current->sighand;
|
|
|
|
if ((unshare_flags & CLONE_SIGHAND) &&
|
|
(sigh && atomic_read(&sigh->count) > 1))
|
|
return -EINVAL;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare vm if it is being shared
|
|
*/
|
|
static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
if ((unshare_flags & CLONE_VM) &&
|
|
(mm && atomic_read(&mm->mm_users) > 1)) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptor table if it is being shared
|
|
*/
|
|
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
|
{
|
|
struct files_struct *fd = current->files;
|
|
int error = 0;
|
|
|
|
if ((unshare_flags & CLONE_FILES) &&
|
|
(fd && atomic_read(&fd->count) > 1)) {
|
|
*new_fdp = dup_fd(fd, &error);
|
|
if (!*new_fdp)
|
|
return error;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
|
|
* supported yet
|
|
*/
|
|
static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp)
|
|
{
|
|
if (unshare_flags & CLONE_SYSVSEM)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifndef CONFIG_IPC_NS
|
|
static inline int unshare_ipcs(unsigned long flags, struct ipc_namespace **ns)
|
|
{
|
|
if (flags & CLONE_NEWIPC)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* unshare allows a process to 'unshare' part of the process
|
|
* context which was originally shared using clone. copy_*
|
|
* functions used by do_fork() cannot be used here directly
|
|
* because they modify an inactive task_struct that is being
|
|
* constructed. Here we are modifying the current, active,
|
|
* task_struct.
|
|
*/
|
|
asmlinkage long sys_unshare(unsigned long unshare_flags)
|
|
{
|
|
int err = 0;
|
|
struct fs_struct *fs, *new_fs = NULL;
|
|
struct namespace *ns, *new_ns = NULL;
|
|
struct sighand_struct *sigh, *new_sigh = NULL;
|
|
struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
|
|
struct files_struct *fd, *new_fd = NULL;
|
|
struct sem_undo_list *new_ulist = NULL;
|
|
struct nsproxy *new_nsproxy = NULL, *old_nsproxy = NULL;
|
|
struct uts_namespace *uts, *new_uts = NULL;
|
|
struct ipc_namespace *ipc, *new_ipc = NULL;
|
|
|
|
check_unshare_flags(&unshare_flags);
|
|
|
|
/* Return -EINVAL for all unsupported flags */
|
|
err = -EINVAL;
|
|
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
|
CLONE_NEWUTS|CLONE_NEWIPC))
|
|
goto bad_unshare_out;
|
|
|
|
if ((err = unshare_thread(unshare_flags)))
|
|
goto bad_unshare_out;
|
|
if ((err = unshare_fs(unshare_flags, &new_fs)))
|
|
goto bad_unshare_cleanup_thread;
|
|
if ((err = unshare_namespace(unshare_flags, &new_ns, new_fs)))
|
|
goto bad_unshare_cleanup_fs;
|
|
if ((err = unshare_sighand(unshare_flags, &new_sigh)))
|
|
goto bad_unshare_cleanup_ns;
|
|
if ((err = unshare_vm(unshare_flags, &new_mm)))
|
|
goto bad_unshare_cleanup_sigh;
|
|
if ((err = unshare_fd(unshare_flags, &new_fd)))
|
|
goto bad_unshare_cleanup_vm;
|
|
if ((err = unshare_semundo(unshare_flags, &new_ulist)))
|
|
goto bad_unshare_cleanup_fd;
|
|
if ((err = unshare_utsname(unshare_flags, &new_uts)))
|
|
goto bad_unshare_cleanup_semundo;
|
|
if ((err = unshare_ipcs(unshare_flags, &new_ipc)))
|
|
goto bad_unshare_cleanup_uts;
|
|
|
|
if (new_ns || new_uts || new_ipc) {
|
|
old_nsproxy = current->nsproxy;
|
|
new_nsproxy = dup_namespaces(old_nsproxy);
|
|
if (!new_nsproxy) {
|
|
err = -ENOMEM;
|
|
goto bad_unshare_cleanup_ipc;
|
|
}
|
|
}
|
|
|
|
if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist ||
|
|
new_uts || new_ipc) {
|
|
|
|
task_lock(current);
|
|
|
|
if (new_nsproxy) {
|
|
current->nsproxy = new_nsproxy;
|
|
new_nsproxy = old_nsproxy;
|
|
}
|
|
|
|
if (new_fs) {
|
|
fs = current->fs;
|
|
current->fs = new_fs;
|
|
new_fs = fs;
|
|
}
|
|
|
|
if (new_ns) {
|
|
ns = current->nsproxy->namespace;
|
|
current->nsproxy->namespace = new_ns;
|
|
new_ns = ns;
|
|
}
|
|
|
|
if (new_sigh) {
|
|
sigh = current->sighand;
|
|
rcu_assign_pointer(current->sighand, new_sigh);
|
|
new_sigh = sigh;
|
|
}
|
|
|
|
if (new_mm) {
|
|
mm = current->mm;
|
|
active_mm = current->active_mm;
|
|
current->mm = new_mm;
|
|
current->active_mm = new_mm;
|
|
activate_mm(active_mm, new_mm);
|
|
new_mm = mm;
|
|
}
|
|
|
|
if (new_fd) {
|
|
fd = current->files;
|
|
current->files = new_fd;
|
|
new_fd = fd;
|
|
}
|
|
|
|
if (new_uts) {
|
|
uts = current->nsproxy->uts_ns;
|
|
current->nsproxy->uts_ns = new_uts;
|
|
new_uts = uts;
|
|
}
|
|
|
|
if (new_ipc) {
|
|
ipc = current->nsproxy->ipc_ns;
|
|
current->nsproxy->ipc_ns = new_ipc;
|
|
new_ipc = ipc;
|
|
}
|
|
|
|
task_unlock(current);
|
|
}
|
|
|
|
if (new_nsproxy)
|
|
put_nsproxy(new_nsproxy);
|
|
|
|
bad_unshare_cleanup_ipc:
|
|
if (new_ipc)
|
|
put_ipc_ns(new_ipc);
|
|
|
|
bad_unshare_cleanup_uts:
|
|
if (new_uts)
|
|
put_uts_ns(new_uts);
|
|
|
|
bad_unshare_cleanup_semundo:
|
|
bad_unshare_cleanup_fd:
|
|
if (new_fd)
|
|
put_files_struct(new_fd);
|
|
|
|
bad_unshare_cleanup_vm:
|
|
if (new_mm)
|
|
mmput(new_mm);
|
|
|
|
bad_unshare_cleanup_sigh:
|
|
if (new_sigh)
|
|
if (atomic_dec_and_test(&new_sigh->count))
|
|
kmem_cache_free(sighand_cachep, new_sigh);
|
|
|
|
bad_unshare_cleanup_ns:
|
|
if (new_ns)
|
|
put_namespace(new_ns);
|
|
|
|
bad_unshare_cleanup_fs:
|
|
if (new_fs)
|
|
put_fs_struct(new_fs);
|
|
|
|
bad_unshare_cleanup_thread:
|
|
bad_unshare_out:
|
|
return err;
|
|
}
|