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bbc2e3ef87
free_pid_ns() operates in a recursive fashion:
free_pid_ns(parent)
put_pid_ns(parent)
kref_put(&ns->kref, free_pid_ns);
free_pid_ns
thus if there was a huge nesting of namespaces the userspace may trigger
avalanche calling of free_pid_ns leading to kernel stack exhausting and a
panic eventually.
This patch turns the recursion into an iterative loop.
Based on a patch by Andrew Vagin.
[akpm@linux-foundation.org: export put_pid_ns() to modules]
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
#ifndef _LINUX_PID_NS_H
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#define _LINUX_PID_NS_H
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#include <linux/sched.h>
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#include <linux/bug.h>
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#include <linux/mm.h>
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#include <linux/threads.h>
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#include <linux/nsproxy.h>
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#include <linux/kref.h>
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struct pidmap {
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atomic_t nr_free;
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void *page;
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};
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#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)
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struct bsd_acct_struct;
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struct pid_namespace {
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struct kref kref;
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struct pidmap pidmap[PIDMAP_ENTRIES];
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int last_pid;
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struct task_struct *child_reaper;
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struct kmem_cache *pid_cachep;
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unsigned int level;
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struct pid_namespace *parent;
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#ifdef CONFIG_PROC_FS
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struct vfsmount *proc_mnt;
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#endif
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#ifdef CONFIG_BSD_PROCESS_ACCT
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struct bsd_acct_struct *bacct;
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#endif
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kgid_t pid_gid;
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int hide_pid;
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int reboot; /* group exit code if this pidns was rebooted */
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};
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extern struct pid_namespace init_pid_ns;
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#ifdef CONFIG_PID_NS
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static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
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{
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if (ns != &init_pid_ns)
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kref_get(&ns->kref);
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return ns;
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}
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extern struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *ns);
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extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
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extern int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd);
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extern void put_pid_ns(struct pid_namespace *ns);
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#else /* !CONFIG_PID_NS */
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#include <linux/err.h>
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static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
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{
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return ns;
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}
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static inline struct pid_namespace *
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copy_pid_ns(unsigned long flags, struct pid_namespace *ns)
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{
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if (flags & CLONE_NEWPID)
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ns = ERR_PTR(-EINVAL);
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return ns;
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}
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static inline void put_pid_ns(struct pid_namespace *ns)
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{
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}
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static inline void zap_pid_ns_processes(struct pid_namespace *ns)
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{
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BUG();
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}
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static inline int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
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{
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return 0;
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}
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#endif /* CONFIG_PID_NS */
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extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk);
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void pidhash_init(void);
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void pidmap_init(void);
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#endif /* _LINUX_PID_NS_H */
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