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![Vasiliy Kulikov](/assets/img/avatar_default.png)
The patch http://lkml.org/lkml/2003/7/13/226 introduced an RLIMIT_NPROC check in set_user() to check for NPROC exceeding via setuid() and similar functions. Before the check there was a possibility to greatly exceed the allowed number of processes by an unprivileged user if the program relied on rlimit only. But the check created new security threat: many poorly written programs simply don't check setuid() return code and believe it cannot fail if executed with root privileges. So, the check is removed in this patch because of too often privilege escalations related to buggy programs. The NPROC can still be enforced in the common code flow of daemons spawning user processes. Most of daemons do fork()+setuid()+execve(). The check introduced in execve() (1) enforces the same limit as in setuid() and (2) doesn't create similar security issues. Neil Brown suggested to track what specific process has exceeded the limit by setting PF_NPROC_EXCEEDED process flag. With the change only this process would fail on execve(), and other processes' execve() behaviour is not changed. Solar Designer suggested to re-check whether NPROC limit is still exceeded at the moment of execve(). If the process was sleeping for days between set*uid() and execve(), and the NPROC counter step down under the limit, the defered execve() failure because NPROC limit was exceeded days ago would be unexpected. If the limit is not exceeded anymore, we clear the flag on successful calls to execve() and fork(). The flag is also cleared on successful calls to set_user() as the limit was exceeded for the previous user, not the current one. Similar check was introduced in -ow patches (without the process flag). v3 - clear PF_NPROC_EXCEEDED on successful calls to set_user(). Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Acked-by: NeilBrown <neilb@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1782 lines
42 KiB
C
1782 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/module.h>
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#include <linux/vmalloc.h>
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#include <linux/completion.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/fdtable.h>
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#include <linux/iocontext.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/mmu_notifier.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/cgroup.h>
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#include <linux/security.h>
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#include <linux/hugetlb.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/compat.h>
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#include <linux/kthread.h>
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#include <linux/task_io_accounting_ops.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/memcontrol.h>
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#include <linux/ftrace.h>
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#include <linux/profile.h>
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#include <linux/rmap.h>
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#include <linux/ksm.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/freezer.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 <linux/tty.h>
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#include <linux/blkdev.h>
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#include <linux/fs_struct.h>
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#include <linux/magic.h>
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#include <linux/perf_event.h>
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#include <linux/posix-timers.h>
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#include <linux/user-return-notifier.h>
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#include <linux/oom.h>
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#include <linux/khugepaged.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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#include <trace/events/sched.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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#ifdef CONFIG_PROVE_RCU
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int lockdep_tasklist_lock_is_held(void)
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{
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return lockdep_is_held(&tasklist_lock);
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}
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EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
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#endif /* #ifdef CONFIG_PROVE_RCU */
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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_possible_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_node(node) \
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kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
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# define free_task_struct(tsk) \
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kmem_cache_free(task_struct_cachep, (tsk))
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static struct kmem_cache *task_struct_cachep;
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#endif
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#ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
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static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
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int node)
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{
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#ifdef CONFIG_DEBUG_STACK_USAGE
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gfp_t mask = GFP_KERNEL | __GFP_ZERO;
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#else
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gfp_t mask = GFP_KERNEL;
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#endif
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struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
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return page ? page_address(page) : NULL;
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}
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static inline void free_thread_info(struct thread_info *ti)
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{
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free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
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}
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#endif
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/* SLAB cache for signal_struct structures (tsk->signal) */
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static struct kmem_cache *signal_cachep;
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/* SLAB cache for sighand_struct structures (tsk->sighand) */
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struct kmem_cache *sighand_cachep;
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/* SLAB cache for files_struct structures (tsk->files) */
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struct kmem_cache *files_cachep;
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/* SLAB cache for fs_struct structures (tsk->fs) */
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struct kmem_cache *fs_cachep;
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/* SLAB cache for vm_area_struct structures */
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struct kmem_cache *vm_area_cachep;
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/* SLAB cache for mm_struct structures (tsk->mm) */
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static struct kmem_cache *mm_cachep;
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static void account_kernel_stack(struct thread_info *ti, int account)
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{
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struct zone *zone = page_zone(virt_to_page(ti));
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mod_zone_page_state(zone, NR_KERNEL_STACK, account);
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}
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void free_task(struct task_struct *tsk)
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{
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prop_local_destroy_single(&tsk->dirties);
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account_kernel_stack(tsk->stack, -1);
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free_thread_info(tsk->stack);
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rt_mutex_debug_task_free(tsk);
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ftrace_graph_exit_task(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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static inline void free_signal_struct(struct signal_struct *sig)
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{
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taskstats_tgid_free(sig);
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sched_autogroup_exit(sig);
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kmem_cache_free(signal_cachep, sig);
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}
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static inline void put_signal_struct(struct signal_struct *sig)
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{
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if (atomic_dec_and_test(&sig->sigcnt))
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free_signal_struct(sig);
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}
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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);
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WARN_ON(atomic_read(&tsk->usage));
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WARN_ON(tsk == current);
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exit_creds(tsk);
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delayacct_tsk_free(tsk);
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put_signal_struct(tsk->signal);
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if (!profile_handoff_task(tsk))
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free_task(tsk);
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}
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EXPORT_SYMBOL_GPL(__put_task_struct);
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/*
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* macro override instead of weak attribute alias, to workaround
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* gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
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*/
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#ifndef arch_task_cache_init
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#define arch_task_cache_init()
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#endif
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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 | SLAB_NOTRACK, NULL);
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#endif
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/* do the arch specific task caches init */
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arch_task_cache_init();
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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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int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
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struct task_struct *src)
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{
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*dst = *src;
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return 0;
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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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unsigned long *stackend;
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int node = tsk_fork_get_node(orig);
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int err;
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prepare_to_copy(orig);
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tsk = alloc_task_struct_node(node);
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if (!tsk)
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return NULL;
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ti = alloc_thread_info_node(tsk, node);
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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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err = arch_dup_task_struct(tsk, orig);
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if (err)
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goto out;
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tsk->stack = ti;
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err = prop_local_init_single(&tsk->dirties);
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if (err)
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goto out;
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setup_thread_stack(tsk, orig);
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clear_user_return_notifier(tsk);
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clear_tsk_need_resched(tsk);
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stackend = end_of_stack(tsk);
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*stackend = STACK_END_MAGIC; /* for overflow detection */
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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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/*
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* One for us, one for whoever does the "release_task()" (usually
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* parent)
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*/
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atomic_set(&tsk->usage, 2);
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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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account_kernel_stack(ti, 1);
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return tsk;
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out:
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free_thread_info(ti);
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free_task_struct(tsk);
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return NULL;
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}
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#ifdef CONFIG_MMU
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static 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, *prev, **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_dup_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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cpumask_clear(mm_cpumask(mm));
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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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retval = ksm_fork(mm, oldmm);
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if (retval)
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goto out;
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retval = khugepaged_fork(mm, oldmm);
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if (retval)
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goto out;
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prev = NULL;
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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, GFP_KERNEL);
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if (!tmp)
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goto fail_nomem;
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*tmp = *mpnt;
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INIT_LIST_HEAD(&tmp->anon_vma_chain);
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pol = mpol_dup(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_mm = mm;
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if (anon_vma_fork(tmp, mpnt))
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goto fail_nomem_anon_vma_fork;
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tmp->vm_flags &= ~VM_LOCKED;
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tmp->vm_next = tmp->vm_prev = NULL;
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file = tmp->vm_file;
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if (file) {
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struct inode *inode = file->f_path.dentry->d_inode;
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struct address_space *mapping = file->f_mapping;
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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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mutex_lock(&mapping->i_mmap_mutex);
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if (tmp->vm_flags & VM_SHARED)
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mapping->i_mmap_writable++;
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flush_dcache_mmap_lock(mapping);
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/* insert tmp into the share list, just after mpnt */
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vma_prio_tree_add(tmp, mpnt);
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flush_dcache_mmap_unlock(mapping);
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mutex_unlock(&mapping->i_mmap_mutex);
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}
|
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|
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/*
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* Clear hugetlb-related page reserves for children. This only
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* affects MAP_PRIVATE mappings. Faults generated by the child
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* are not guaranteed to succeed, even if read-only
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*/
|
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if (is_vm_hugetlb_page(tmp))
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reset_vma_resv_huge_pages(tmp);
|
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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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tmp->vm_prev = prev;
|
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prev = tmp;
|
|
|
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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;
|
|
|
|
mm->map_count++;
|
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retval = copy_page_range(mm, oldmm, mpnt);
|
|
|
|
if (tmp->vm_ops && tmp->vm_ops->open)
|
|
tmp->vm_ops->open(tmp);
|
|
|
|
if (retval)
|
|
goto out;
|
|
}
|
|
/* a new mm has just been created */
|
|
arch_dup_mmap(oldmm, mm);
|
|
retval = 0;
|
|
out:
|
|
up_write(&mm->mmap_sem);
|
|
flush_tlb_mm(oldmm);
|
|
up_write(&oldmm->mmap_sem);
|
|
return retval;
|
|
fail_nomem_anon_vma_fork:
|
|
mpol_put(pol);
|
|
fail_nomem_policy:
|
|
kmem_cache_free(vm_area_cachep, tmp);
|
|
fail_nomem:
|
|
retval = -ENOMEM;
|
|
vm_unacct_memory(charge);
|
|
goto out;
|
|
}
|
|
|
|
static inline int mm_alloc_pgd(struct mm_struct *mm)
|
|
{
|
|
mm->pgd = pgd_alloc(mm);
|
|
if (unlikely(!mm->pgd))
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static inline void mm_free_pgd(struct mm_struct *mm)
|
|
{
|
|
pgd_free(mm, mm->pgd);
|
|
}
|
|
#else
|
|
#define dup_mmap(mm, oldmm) (0)
|
|
#define mm_alloc_pgd(mm) (0)
|
|
#define mm_free_pgd(mm)
|
|
#endif /* CONFIG_MMU */
|
|
|
|
__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
|
|
|
|
#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
|
|
#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
|
|
|
|
static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
|
|
|
|
static int __init coredump_filter_setup(char *s)
|
|
{
|
|
default_dump_filter =
|
|
(simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
|
|
MMF_DUMP_FILTER_MASK;
|
|
return 1;
|
|
}
|
|
|
|
__setup("coredump_filter=", coredump_filter_setup);
|
|
|
|
#include <linux/init_task.h>
|
|
|
|
static void mm_init_aio(struct mm_struct *mm)
|
|
{
|
|
#ifdef CONFIG_AIO
|
|
spin_lock_init(&mm->ioctx_lock);
|
|
INIT_HLIST_HEAD(&mm->ioctx_list);
|
|
#endif
|
|
}
|
|
|
|
static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
atomic_set(&mm->mm_users, 1);
|
|
atomic_set(&mm->mm_count, 1);
|
|
init_rwsem(&mm->mmap_sem);
|
|
INIT_LIST_HEAD(&mm->mmlist);
|
|
mm->flags = (current->mm) ?
|
|
(current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
|
|
mm->core_state = NULL;
|
|
mm->nr_ptes = 0;
|
|
memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
|
|
spin_lock_init(&mm->page_table_lock);
|
|
mm->free_area_cache = TASK_UNMAPPED_BASE;
|
|
mm->cached_hole_size = ~0UL;
|
|
mm_init_aio(mm);
|
|
mm_init_owner(mm, p);
|
|
atomic_set(&mm->oom_disable_count, 0);
|
|
|
|
if (likely(!mm_alloc_pgd(mm))) {
|
|
mm->def_flags = 0;
|
|
mmu_notifier_mm_init(mm);
|
|
return mm;
|
|
}
|
|
|
|
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));
|
|
mm_init_cpumask(mm);
|
|
return mm_init(mm, current);
|
|
}
|
|
|
|
/*
|
|
* Called when the last reference to the mm
|
|
* is dropped: either by a lazy thread or by
|
|
* mmput. Free the page directory and the mm.
|
|
*/
|
|
void __mmdrop(struct mm_struct *mm)
|
|
{
|
|
BUG_ON(mm == &init_mm);
|
|
mm_free_pgd(mm);
|
|
destroy_context(mm);
|
|
mmu_notifier_mm_destroy(mm);
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
VM_BUG_ON(mm->pmd_huge_pte);
|
|
#endif
|
|
free_mm(mm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__mmdrop);
|
|
|
|
/*
|
|
* Decrement the use count and release all resources for an mm.
|
|
*/
|
|
void mmput(struct mm_struct *mm)
|
|
{
|
|
might_sleep();
|
|
|
|
if (atomic_dec_and_test(&mm->mm_users)) {
|
|
exit_aio(mm);
|
|
ksm_exit(mm);
|
|
khugepaged_exit(mm); /* must run before exit_mmap */
|
|
exit_mmap(mm);
|
|
set_mm_exe_file(mm, NULL);
|
|
if (!list_empty(&mm->mmlist)) {
|
|
spin_lock(&mmlist_lock);
|
|
list_del(&mm->mmlist);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
put_swap_token(mm);
|
|
if (mm->binfmt)
|
|
module_put(mm->binfmt->module);
|
|
mmdrop(mm);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(mmput);
|
|
|
|
/*
|
|
* We added or removed a vma mapping the executable. The vmas are only mapped
|
|
* during exec and are not mapped with the mmap system call.
|
|
* Callers must hold down_write() on the mm's mmap_sem for these
|
|
*/
|
|
void added_exe_file_vma(struct mm_struct *mm)
|
|
{
|
|
mm->num_exe_file_vmas++;
|
|
}
|
|
|
|
void removed_exe_file_vma(struct mm_struct *mm)
|
|
{
|
|
mm->num_exe_file_vmas--;
|
|
if ((mm->num_exe_file_vmas == 0) && mm->exe_file) {
|
|
fput(mm->exe_file);
|
|
mm->exe_file = NULL;
|
|
}
|
|
|
|
}
|
|
|
|
void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
|
{
|
|
if (new_exe_file)
|
|
get_file(new_exe_file);
|
|
if (mm->exe_file)
|
|
fput(mm->exe_file);
|
|
mm->exe_file = new_exe_file;
|
|
mm->num_exe_file_vmas = 0;
|
|
}
|
|
|
|
struct file *get_mm_exe_file(struct mm_struct *mm)
|
|
{
|
|
struct file *exe_file;
|
|
|
|
/* We need mmap_sem to protect against races with removal of
|
|
* VM_EXECUTABLE vmas */
|
|
down_read(&mm->mmap_sem);
|
|
exe_file = mm->exe_file;
|
|
if (exe_file)
|
|
get_file(exe_file);
|
|
up_read(&mm->mmap_sem);
|
|
return exe_file;
|
|
}
|
|
|
|
static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
|
|
{
|
|
/* It's safe to write the exe_file pointer without exe_file_lock because
|
|
* this is called during fork when the task is not yet in /proc */
|
|
newmm->exe_file = get_mm_exe_file(oldmm);
|
|
}
|
|
|
|
/**
|
|
* get_task_mm - acquire a reference to the task's mm
|
|
*
|
|
* Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
|
|
* this kernel workthread has transiently adopted a user mm with use_mm,
|
|
* to do its AIO) is not set and if so returns a reference to it, after
|
|
* bumping up the use count. User must release the mm via mmput()
|
|
* after use. Typically used by /proc and ptrace.
|
|
*/
|
|
struct mm_struct *get_task_mm(struct task_struct *task)
|
|
{
|
|
struct mm_struct *mm;
|
|
|
|
task_lock(task);
|
|
mm = task->mm;
|
|
if (mm) {
|
|
if (task->flags & PF_KTHREAD)
|
|
mm = NULL;
|
|
else
|
|
atomic_inc(&mm->mm_users);
|
|
}
|
|
task_unlock(task);
|
|
return mm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_task_mm);
|
|
|
|
/* 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 futexes when releasing the mm */
|
|
#ifdef CONFIG_FUTEX
|
|
if (unlikely(tsk->robust_list)) {
|
|
exit_robust_list(tsk);
|
|
tsk->robust_list = NULL;
|
|
}
|
|
#ifdef CONFIG_COMPAT
|
|
if (unlikely(tsk->compat_robust_list)) {
|
|
compat_exit_robust_list(tsk);
|
|
tsk->compat_robust_list = NULL;
|
|
}
|
|
#endif
|
|
if (unlikely(!list_empty(&tsk->pi_state_list)))
|
|
exit_pi_state_list(tsk);
|
|
#endif
|
|
|
|
/* 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 we're exiting normally, clear a user-space tid field if
|
|
* requested. We leave this alone when dying by signal, to leave
|
|
* the value intact in a core dump, and to save the unnecessary
|
|
* trouble otherwise. Userland only wants this done for a sys_exit.
|
|
*/
|
|
if (tsk->clear_child_tid) {
|
|
if (!(tsk->flags & PF_SIGNALED) &&
|
|
atomic_read(&mm->mm_users) > 1) {
|
|
/*
|
|
* We don't check the error code - if userspace has
|
|
* not set up a proper pointer then tough luck.
|
|
*/
|
|
put_user(0, tsk->clear_child_tid);
|
|
sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
|
1, NULL, NULL, 0);
|
|
}
|
|
tsk->clear_child_tid = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocate a new mm structure and copy contents from the
|
|
* mm structure of the passed in task structure.
|
|
*/
|
|
struct mm_struct *dup_mm(struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm = current->mm;
|
|
int err;
|
|
|
|
if (!oldmm)
|
|
return NULL;
|
|
|
|
mm = allocate_mm();
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
memcpy(mm, oldmm, sizeof(*mm));
|
|
mm_init_cpumask(mm);
|
|
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
mm->pmd_huge_pte = NULL;
|
|
#endif
|
|
|
|
if (!mm_init(mm, tsk))
|
|
goto fail_nomem;
|
|
|
|
if (init_new_context(tsk, mm))
|
|
goto fail_nocontext;
|
|
|
|
dup_mm_exe_file(oldmm, mm);
|
|
|
|
err = dup_mmap(mm, oldmm);
|
|
if (err)
|
|
goto free_pt;
|
|
|
|
mm->hiwater_rss = get_mm_rss(mm);
|
|
mm->hiwater_vm = mm->total_vm;
|
|
|
|
if (mm->binfmt && !try_module_get(mm->binfmt->module))
|
|
goto free_pt;
|
|
|
|
return mm;
|
|
|
|
free_pt:
|
|
/* don't put binfmt in mmput, we haven't got module yet */
|
|
mm->binfmt = NULL;
|
|
mmput(mm);
|
|
|
|
fail_nomem:
|
|
return NULL;
|
|
|
|
fail_nocontext:
|
|
/*
|
|
* If init_new_context() failed, we cannot use mmput() to free the mm
|
|
* because it calls destroy_context()
|
|
*/
|
|
mm_free_pgd(mm);
|
|
free_mm(mm);
|
|
return NULL;
|
|
}
|
|
|
|
static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm;
|
|
int retval;
|
|
|
|
tsk->min_flt = tsk->maj_flt = 0;
|
|
tsk->nvcsw = tsk->nivcsw = 0;
|
|
#ifdef CONFIG_DETECT_HUNG_TASK
|
|
tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
|
|
#endif
|
|
|
|
tsk->mm = NULL;
|
|
tsk->active_mm = NULL;
|
|
|
|
/*
|
|
* Are we cloning a kernel thread?
|
|
*
|
|
* We need to steal a active VM for that..
|
|
*/
|
|
oldmm = current->mm;
|
|
if (!oldmm)
|
|
return 0;
|
|
|
|
if (clone_flags & CLONE_VM) {
|
|
atomic_inc(&oldmm->mm_users);
|
|
mm = oldmm;
|
|
goto good_mm;
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
mm = dup_mm(tsk);
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
good_mm:
|
|
/* Initializing for Swap token stuff */
|
|
mm->token_priority = 0;
|
|
mm->last_interval = 0;
|
|
if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
|
|
atomic_inc(&mm->oom_disable_count);
|
|
|
|
tsk->mm = mm;
|
|
tsk->active_mm = mm;
|
|
return 0;
|
|
|
|
fail_nomem:
|
|
return retval;
|
|
}
|
|
|
|
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
if (clone_flags & CLONE_FS) {
|
|
/* tsk->fs is already what we want */
|
|
spin_lock(&fs->lock);
|
|
if (fs->in_exec) {
|
|
spin_unlock(&fs->lock);
|
|
return -EAGAIN;
|
|
}
|
|
fs->users++;
|
|
spin_unlock(&fs->lock);
|
|
return 0;
|
|
}
|
|
tsk->fs = copy_fs_struct(fs);
|
|
if (!tsk->fs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct files_struct *oldf, *newf;
|
|
int error = 0;
|
|
|
|
/*
|
|
* A background process may not have any files ...
|
|
*/
|
|
oldf = current->files;
|
|
if (!oldf)
|
|
goto out;
|
|
|
|
if (clone_flags & CLONE_FILES) {
|
|
atomic_inc(&oldf->count);
|
|
goto out;
|
|
}
|
|
|
|
newf = dup_fd(oldf, &error);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
tsk->files = newf;
|
|
error = 0;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
#ifdef CONFIG_BLOCK
|
|
struct io_context *ioc = current->io_context;
|
|
|
|
if (!ioc)
|
|
return 0;
|
|
/*
|
|
* Share io context with parent, if CLONE_IO is set
|
|
*/
|
|
if (clone_flags & CLONE_IO) {
|
|
tsk->io_context = ioc_task_link(ioc);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
} else if (ioprio_valid(ioc->ioprio)) {
|
|
tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
|
|
if (unlikely(!tsk->io_context))
|
|
return -ENOMEM;
|
|
|
|
tsk->io_context->ioprio = ioc->ioprio;
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct sighand_struct *sig;
|
|
|
|
if (clone_flags & CLONE_SIGHAND) {
|
|
atomic_inc(¤t->sighand->count);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
|
rcu_assign_pointer(tsk->sighand, sig);
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
atomic_set(&sig->count, 1);
|
|
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_sighand(struct sighand_struct *sighand)
|
|
{
|
|
if (atomic_dec_and_test(&sighand->count))
|
|
kmem_cache_free(sighand_cachep, sighand);
|
|
}
|
|
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a thread group.
|
|
*/
|
|
static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
|
{
|
|
unsigned long cpu_limit;
|
|
|
|
/* Thread group counters. */
|
|
thread_group_cputime_init(sig);
|
|
|
|
cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
if (cpu_limit != RLIM_INFINITY) {
|
|
sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
|
|
sig->cputimer.running = 1;
|
|
}
|
|
|
|
/* The timer lists. */
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
}
|
|
|
|
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig;
|
|
|
|
if (clone_flags & CLONE_THREAD)
|
|
return 0;
|
|
|
|
sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
|
|
tsk->signal = sig;
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
|
|
sig->nr_threads = 1;
|
|
atomic_set(&sig->live, 1);
|
|
atomic_set(&sig->sigcnt, 1);
|
|
init_waitqueue_head(&sig->wait_chldexit);
|
|
if (clone_flags & CLONE_NEWPID)
|
|
sig->flags |= SIGNAL_UNKILLABLE;
|
|
sig->curr_target = tsk;
|
|
init_sigpending(&sig->shared_pending);
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
sig->real_timer.function = it_real_fn;
|
|
|
|
task_lock(current->group_leader);
|
|
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
|
task_unlock(current->group_leader);
|
|
|
|
posix_cpu_timers_init_group(sig);
|
|
|
|
tty_audit_fork(sig);
|
|
sched_autogroup_fork(sig);
|
|
|
|
#ifdef CONFIG_CGROUPS
|
|
init_rwsem(&sig->threadgroup_fork_lock);
|
|
#endif
|
|
|
|
sig->oom_adj = current->signal->oom_adj;
|
|
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);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void copy_flags(unsigned long clone_flags, struct task_struct *p)
|
|
{
|
|
unsigned long new_flags = p->flags;
|
|
|
|
new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
|
|
new_flags |= PF_FORKNOEXEC;
|
|
new_flags |= PF_STARTING;
|
|
p->flags = new_flags;
|
|
clear_freeze_flag(p);
|
|
}
|
|
|
|
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
|
|
plist_head_init(&p->pi_waiters);
|
|
p->pi_blocked_on = NULL;
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_MM_OWNER
|
|
void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
mm->owner = p;
|
|
}
|
|
#endif /* CONFIG_MM_OWNER */
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a single task.
|
|
*/
|
|
static void posix_cpu_timers_init(struct task_struct *tsk)
|
|
{
|
|
tsk->cputime_expires.prof_exp = cputime_zero;
|
|
tsk->cputime_expires.virt_exp = cputime_zero;
|
|
tsk->cputime_expires.sched_exp = 0;
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[2]);
|
|
}
|
|
|
|
/*
|
|
* 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 *child_tidptr,
|
|
struct pid *pid,
|
|
int trace)
|
|
{
|
|
int retval;
|
|
struct task_struct *p;
|
|
int cgroup_callbacks_done = 0;
|
|
|
|
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);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
retval = security_task_create(clone_flags);
|
|
if (retval)
|
|
goto fork_out;
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
ftrace_graph_init_task(p);
|
|
|
|
rt_mutex_init_task(p);
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
|
|
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
|
#endif
|
|
retval = -EAGAIN;
|
|
if (atomic_read(&p->real_cred->user->processes) >=
|
|
task_rlimit(p, RLIMIT_NPROC)) {
|
|
if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
|
|
p->real_cred->user != INIT_USER)
|
|
goto bad_fork_free;
|
|
}
|
|
current->flags &= ~PF_NPROC_EXCEEDED;
|
|
|
|
retval = copy_creds(p, clone_flags);
|
|
if (retval < 0)
|
|
goto bad_fork_free;
|
|
|
|
/*
|
|
* If multiple threads are within copy_process(), then this check
|
|
* triggers too late. This doesn't hurt, the check is only there
|
|
* to stop root fork bombs.
|
|
*/
|
|
retval = -EAGAIN;
|
|
if (nr_threads >= max_threads)
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (!try_module_get(task_thread_info(p)->exec_domain->module))
|
|
goto bad_fork_cleanup_count;
|
|
|
|
p->did_exec = 0;
|
|
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
|
|
copy_flags(clone_flags, p);
|
|
INIT_LIST_HEAD(&p->children);
|
|
INIT_LIST_HEAD(&p->sibling);
|
|
rcu_copy_process(p);
|
|
p->vfork_done = NULL;
|
|
spin_lock_init(&p->alloc_lock);
|
|
|
|
init_sigpending(&p->pending);
|
|
|
|
p->utime = cputime_zero;
|
|
p->stime = cputime_zero;
|
|
p->gtime = cputime_zero;
|
|
p->utimescaled = cputime_zero;
|
|
p->stimescaled = cputime_zero;
|
|
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
|
|
p->prev_utime = cputime_zero;
|
|
p->prev_stime = cputime_zero;
|
|
#endif
|
|
#if defined(SPLIT_RSS_COUNTING)
|
|
memset(&p->rss_stat, 0, sizeof(p->rss_stat));
|
|
#endif
|
|
|
|
p->default_timer_slack_ns = current->timer_slack_ns;
|
|
|
|
task_io_accounting_init(&p->ioac);
|
|
acct_clear_integrals(p);
|
|
|
|
posix_cpu_timers_init(p);
|
|
|
|
do_posix_clock_monotonic_gettime(&p->start_time);
|
|
p->real_start_time = p->start_time;
|
|
monotonic_to_bootbased(&p->real_start_time);
|
|
p->io_context = NULL;
|
|
p->audit_context = NULL;
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_fork_read_lock(current);
|
|
cgroup_fork(p);
|
|
#ifdef CONFIG_NUMA
|
|
p->mempolicy = mpol_dup(p->mempolicy);
|
|
if (IS_ERR(p->mempolicy)) {
|
|
retval = PTR_ERR(p->mempolicy);
|
|
p->mempolicy = NULL;
|
|
goto bad_fork_cleanup_cgroup;
|
|
}
|
|
mpol_fix_fork_child_flag(p);
|
|
#endif
|
|
#ifdef CONFIG_CPUSETS
|
|
p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
|
|
p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
|
|
#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
|
|
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
|
|
p->memcg_batch.do_batch = 0;
|
|
p->memcg_batch.memcg = NULL;
|
|
#endif
|
|
|
|
/* Perform scheduler related setup. Assign this task to a CPU. */
|
|
sched_fork(p);
|
|
|
|
retval = perf_event_init_task(p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
retval = audit_alloc(p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
/* copy all the process information */
|
|
retval = copy_semundo(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_audit;
|
|
retval = copy_files(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_semundo;
|
|
retval = copy_fs(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_files;
|
|
retval = copy_sighand(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_fs;
|
|
retval = copy_signal(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_sighand;
|
|
retval = copy_mm(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_signal;
|
|
retval = copy_namespaces(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_mm;
|
|
retval = copy_io(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_namespaces;
|
|
retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
|
|
if (retval)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (pid != &init_struct_pid) {
|
|
retval = -ENOMEM;
|
|
pid = alloc_pid(p->nsproxy->pid_ns);
|
|
if (!pid)
|
|
goto bad_fork_cleanup_io;
|
|
}
|
|
|
|
p->pid = pid_nr(pid);
|
|
p->tgid = p->pid;
|
|
if (clone_flags & CLONE_THREAD)
|
|
p->tgid = current->tgid;
|
|
|
|
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
|
|
/*
|
|
* Clear TID on mm_release()?
|
|
*/
|
|
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
|
|
#ifdef CONFIG_BLOCK
|
|
p->plug = NULL;
|
|
#endif
|
|
#ifdef CONFIG_FUTEX
|
|
p->robust_list = NULL;
|
|
#ifdef CONFIG_COMPAT
|
|
p->compat_robust_list = NULL;
|
|
#endif
|
|
INIT_LIST_HEAD(&p->pi_state_list);
|
|
p->pi_state_cache = NULL;
|
|
#endif
|
|
/*
|
|
* sigaltstack should be cleared when sharing the same VM
|
|
*/
|
|
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
|
p->sas_ss_sp = p->sas_ss_size = 0;
|
|
|
|
/*
|
|
* Syscall tracing and stepping should be turned off in the
|
|
* child regardless of CLONE_PTRACE.
|
|
*/
|
|
user_disable_single_step(p);
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
|
|
#ifdef TIF_SYSCALL_EMU
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
|
|
#endif
|
|
clear_all_latency_tracing(p);
|
|
|
|
/* ok, now we should be set up.. */
|
|
p->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);
|
|
|
|
/* Now that the task is set up, run cgroup callbacks if
|
|
* necessary. We need to run them before the task is visible
|
|
* on the tasklist. */
|
|
cgroup_fork_callbacks(p);
|
|
cgroup_callbacks_done = 1;
|
|
|
|
/* Need tasklist lock for parent etc handling! */
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
/* CLONE_PARENT re-uses the old parent */
|
|
if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
|
|
p->real_parent = current->real_parent;
|
|
p->parent_exec_id = current->parent_exec_id;
|
|
} else {
|
|
p->real_parent = current;
|
|
p->parent_exec_id = current->self_exec_id;
|
|
}
|
|
|
|
spin_lock(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Process group and session signals need to be delivered to just the
|
|
* parent before the fork or both the parent and the child after the
|
|
* fork. Restart if a signal comes in before we add the new process to
|
|
* it's process group.
|
|
* A fatal signal pending means that current will exit, so the new
|
|
* thread can't slip out of an OOM kill (or normal SIGKILL).
|
|
*/
|
|
recalc_sigpending();
|
|
if (signal_pending(current)) {
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
if (clone_flags & CLONE_THREAD) {
|
|
current->signal->nr_threads++;
|
|
atomic_inc(¤t->signal->live);
|
|
atomic_inc(¤t->signal->sigcnt);
|
|
p->group_leader = current->group_leader;
|
|
list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
|
|
}
|
|
|
|
if (likely(p->pid)) {
|
|
ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
|
|
|
|
if (thread_group_leader(p)) {
|
|
if (is_child_reaper(pid))
|
|
p->nsproxy->pid_ns->child_reaper = p;
|
|
|
|
p->signal->leader_pid = pid;
|
|
p->signal->tty = tty_kref_get(current->signal->tty);
|
|
attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
|
|
attach_pid(p, PIDTYPE_SID, task_session(current));
|
|
list_add_tail(&p->sibling, &p->real_parent->children);
|
|
list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
|
__this_cpu_inc(process_counts);
|
|
}
|
|
attach_pid(p, PIDTYPE_PID, pid);
|
|
nr_threads++;
|
|
}
|
|
|
|
total_forks++;
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
proc_fork_connector(p);
|
|
cgroup_post_fork(p);
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_fork_read_unlock(current);
|
|
perf_event_fork(p);
|
|
return p;
|
|
|
|
bad_fork_free_pid:
|
|
if (pid != &init_struct_pid)
|
|
free_pid(pid);
|
|
bad_fork_cleanup_io:
|
|
if (p->io_context)
|
|
exit_io_context(p);
|
|
bad_fork_cleanup_namespaces:
|
|
exit_task_namespaces(p);
|
|
bad_fork_cleanup_mm:
|
|
if (p->mm) {
|
|
task_lock(p);
|
|
if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
|
|
atomic_dec(&p->mm->oom_disable_count);
|
|
task_unlock(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_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_policy:
|
|
perf_event_free_task(p);
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(p->mempolicy);
|
|
bad_fork_cleanup_cgroup:
|
|
#endif
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_fork_read_unlock(current);
|
|
cgroup_exit(p, cgroup_callbacks_done);
|
|
delayacct_tsk_free(p);
|
|
module_put(task_thread_info(p)->exec_domain->module);
|
|
bad_fork_cleanup_count:
|
|
atomic_dec(&p->cred->user->processes);
|
|
exit_creds(p);
|
|
bad_fork_free:
|
|
free_task(p);
|
|
fork_out:
|
|
return ERR_PTR(retval);
|
|
}
|
|
|
|
noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
|
|
{
|
|
memset(regs, 0, sizeof(struct pt_regs));
|
|
return regs;
|
|
}
|
|
|
|
static inline void init_idle_pids(struct pid_link *links)
|
|
{
|
|
enum pid_type type;
|
|
|
|
for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
|
|
INIT_HLIST_NODE(&links[type].node); /* not really needed */
|
|
links[type].pid = &init_struct_pid;
|
|
}
|
|
}
|
|
|
|
struct task_struct * __cpuinit fork_idle(int cpu)
|
|
{
|
|
struct task_struct *task;
|
|
struct pt_regs regs;
|
|
|
|
task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
|
|
&init_struct_pid, 0);
|
|
if (!IS_ERR(task)) {
|
|
init_idle_pids(task->pids);
|
|
init_idle(task, cpu);
|
|
}
|
|
|
|
return task;
|
|
}
|
|
|
|
/*
|
|
* Ok, this is the main fork-routine.
|
|
*
|
|
* It copies the process, and if successful kick-starts
|
|
* it and waits for it to finish using the VM if required.
|
|
*/
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
struct pt_regs *regs,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
struct task_struct *p;
|
|
int trace = 0;
|
|
long nr;
|
|
|
|
/*
|
|
* Do some preliminary argument and permissions checking before we
|
|
* actually start allocating stuff
|
|
*/
|
|
if (clone_flags & CLONE_NEWUSER) {
|
|
if (clone_flags & CLONE_THREAD)
|
|
return -EINVAL;
|
|
/* hopefully this check will go away when userns support is
|
|
* complete
|
|
*/
|
|
if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
|
|
!capable(CAP_SETGID))
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* 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 (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
|
|
if (clone_flags & CLONE_VFORK)
|
|
trace = PTRACE_EVENT_VFORK;
|
|
else if ((clone_flags & CSIGNAL) != SIGCHLD)
|
|
trace = PTRACE_EVENT_CLONE;
|
|
else
|
|
trace = PTRACE_EVENT_FORK;
|
|
|
|
if (likely(!ptrace_event_enabled(current, trace)))
|
|
trace = 0;
|
|
}
|
|
|
|
p = copy_process(clone_flags, stack_start, regs, stack_size,
|
|
child_tidptr, NULL, trace);
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
if (!IS_ERR(p)) {
|
|
struct completion vfork;
|
|
|
|
trace_sched_process_fork(current, p);
|
|
|
|
nr = task_pid_vnr(p);
|
|
|
|
if (clone_flags & CLONE_PARENT_SETTID)
|
|
put_user(nr, parent_tidptr);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
p->vfork_done = &vfork;
|
|
init_completion(&vfork);
|
|
}
|
|
|
|
audit_finish_fork(p);
|
|
|
|
/*
|
|
* We set PF_STARTING at creation in case tracing wants to
|
|
* use this to distinguish a fully live task from one that
|
|
* hasn't finished SIGSTOP raising yet. Now we clear it
|
|
* and set the child going.
|
|
*/
|
|
p->flags &= ~PF_STARTING;
|
|
|
|
wake_up_new_task(p);
|
|
|
|
/* forking complete and child started to run, tell ptracer */
|
|
if (unlikely(trace))
|
|
ptrace_event(trace, nr);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
freezer_do_not_count();
|
|
wait_for_completion(&vfork);
|
|
freezer_count();
|
|
ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
|
|
}
|
|
} else {
|
|
nr = PTR_ERR(p);
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
|
#define ARCH_MIN_MMSTRUCT_ALIGN 0
|
|
#endif
|
|
|
|
static void sighand_ctor(void *data)
|
|
{
|
|
struct sighand_struct *sighand = data;
|
|
|
|
spin_lock_init(&sighand->siglock);
|
|
init_waitqueue_head(&sighand->signalfd_wqh);
|
|
}
|
|
|
|
void __init proc_caches_init(void)
|
|
{
|
|
sighand_cachep = kmem_cache_create("sighand_cache",
|
|
sizeof(struct sighand_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
|
|
SLAB_NOTRACK, sighand_ctor);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
/*
|
|
* FIXME! The "sizeof(struct mm_struct)" currently includes the
|
|
* whole struct cpumask for the OFFSTACK case. We could change
|
|
* this to *only* allocate as much of it as required by the
|
|
* maximum number of CPU's we can ever have. The cpumask_allocation
|
|
* is at the end of the structure, exactly for that reason.
|
|
*/
|
|
mm_cachep = kmem_cache_create("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
|
|
mmap_init();
|
|
nsproxy_cache_init();
|
|
}
|
|
|
|
/*
|
|
* Check constraints on flags passed to the unshare system call.
|
|
*/
|
|
static int check_unshare_flags(unsigned long unshare_flags)
|
|
{
|
|
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
|
CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
|
|
return -EINVAL;
|
|
/*
|
|
* Not implemented, but pretend it works if there is nothing to
|
|
* unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
|
|
* needs to unshare vm.
|
|
*/
|
|
if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
|
|
/* FIXME: get_task_mm() increments ->mm_users */
|
|
if (atomic_read(¤t->mm->mm_users) > 1)
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare the filesystem structure if it is being shared
|
|
*/
|
|
static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
|
|
if (!(unshare_flags & CLONE_FS) || !fs)
|
|
return 0;
|
|
|
|
/* don't need lock here; in the worst case we'll do useless copy */
|
|
if (fs->users == 1)
|
|
return 0;
|
|
|
|
*new_fsp = copy_fs_struct(fs);
|
|
if (!*new_fsp)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptor table if it is being shared
|
|
*/
|
|
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
|
{
|
|
struct files_struct *fd = current->files;
|
|
int error = 0;
|
|
|
|
if ((unshare_flags & CLONE_FILES) &&
|
|
(fd && atomic_read(&fd->count) > 1)) {
|
|
*new_fdp = dup_fd(fd, &error);
|
|
if (!*new_fdp)
|
|
return error;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* unshare allows a process to 'unshare' part of the process
|
|
* context which was originally shared using clone. copy_*
|
|
* functions used by do_fork() cannot be used here directly
|
|
* because they modify an inactive task_struct that is being
|
|
* constructed. Here we are modifying the current, active,
|
|
* task_struct.
|
|
*/
|
|
SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
|
{
|
|
struct fs_struct *fs, *new_fs = NULL;
|
|
struct files_struct *fd, *new_fd = NULL;
|
|
struct nsproxy *new_nsproxy = NULL;
|
|
int do_sysvsem = 0;
|
|
int err;
|
|
|
|
err = check_unshare_flags(unshare_flags);
|
|
if (err)
|
|
goto bad_unshare_out;
|
|
|
|
/*
|
|
* If unsharing namespace, must also unshare filesystem information.
|
|
*/
|
|
if (unshare_flags & CLONE_NEWNS)
|
|
unshare_flags |= CLONE_FS;
|
|
/*
|
|
* CLONE_NEWIPC must also detach from the undolist: after switching
|
|
* to a new ipc namespace, the semaphore arrays from the old
|
|
* namespace are unreachable.
|
|
*/
|
|
if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
|
do_sysvsem = 1;
|
|
err = unshare_fs(unshare_flags, &new_fs);
|
|
if (err)
|
|
goto bad_unshare_out;
|
|
err = unshare_fd(unshare_flags, &new_fd);
|
|
if (err)
|
|
goto bad_unshare_cleanup_fs;
|
|
err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs);
|
|
if (err)
|
|
goto bad_unshare_cleanup_fd;
|
|
|
|
if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
|
|
if (do_sysvsem) {
|
|
/*
|
|
* CLONE_SYSVSEM is equivalent to sys_exit().
|
|
*/
|
|
exit_sem(current);
|
|
}
|
|
|
|
if (new_nsproxy) {
|
|
switch_task_namespaces(current, new_nsproxy);
|
|
new_nsproxy = NULL;
|
|
}
|
|
|
|
task_lock(current);
|
|
|
|
if (new_fs) {
|
|
fs = current->fs;
|
|
spin_lock(&fs->lock);
|
|
current->fs = new_fs;
|
|
if (--fs->users)
|
|
new_fs = NULL;
|
|
else
|
|
new_fs = fs;
|
|
spin_unlock(&fs->lock);
|
|
}
|
|
|
|
if (new_fd) {
|
|
fd = current->files;
|
|
current->files = new_fd;
|
|
new_fd = fd;
|
|
}
|
|
|
|
task_unlock(current);
|
|
}
|
|
|
|
if (new_nsproxy)
|
|
put_nsproxy(new_nsproxy);
|
|
|
|
bad_unshare_cleanup_fd:
|
|
if (new_fd)
|
|
put_files_struct(new_fd);
|
|
|
|
bad_unshare_cleanup_fs:
|
|
if (new_fs)
|
|
free_fs_struct(new_fs);
|
|
|
|
bad_unshare_out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Helper to unshare the files of the current task.
|
|
* We don't want to expose copy_files internals to
|
|
* the exec layer of the kernel.
|
|
*/
|
|
|
|
int unshare_files(struct files_struct **displaced)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct files_struct *copy = NULL;
|
|
int error;
|
|
|
|
error = unshare_fd(CLONE_FILES, ©);
|
|
if (error || !copy) {
|
|
*displaced = NULL;
|
|
return error;
|
|
}
|
|
*displaced = task->files;
|
|
task_lock(task);
|
|
task->files = copy;
|
|
task_unlock(task);
|
|
return 0;
|
|
}
|