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858d72ead4
When a task enters a new namespace via a clone() or unshare(), a new cgroup is created and the task moves into it. This version names cgroups which are automatically created using cgroup_clone() as "node_<pid>" where pid is the pid of the unsharing or cloned process. (Thanks Pavel for the idea) This is safe because if the process unshares again, it will create /cgroups/(...)/node_<pid>/node_<pid> The only possibilities (AFAICT) for a -EEXIST on unshare are 1. pid wraparound 2. a process fails an unshare, then tries again. Case 1 is unlikely enough that I ignore it (at least for now). In case 2, the node_<pid> will be empty and can be rmdir'ed to make the subsequent unshare() succeed. Changelog: Name cloned cgroups as "node_<pid>". [clg@fr.ibm.com: fix order of cgroup subsystems in init/Kconfig] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
#ifndef _LINUX_NSPROXY_H
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#define _LINUX_NSPROXY_H
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#include <linux/spinlock.h>
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#include <linux/sched.h>
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struct mnt_namespace;
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struct uts_namespace;
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struct ipc_namespace;
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struct pid_namespace;
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/*
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* A structure to contain pointers to all per-process
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* namespaces - fs (mount), uts, network, sysvipc, etc.
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*
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* 'count' is the number of tasks holding a reference.
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* The count for each namespace, then, will be the number
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* of nsproxies pointing to it, not the number of tasks.
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*
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* The nsproxy is shared by tasks which share all namespaces.
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* As soon as a single namespace is cloned or unshared, the
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* nsproxy is copied.
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*/
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struct nsproxy {
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atomic_t count;
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struct uts_namespace *uts_ns;
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struct ipc_namespace *ipc_ns;
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struct mnt_namespace *mnt_ns;
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struct pid_namespace *pid_ns;
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struct user_namespace *user_ns;
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struct net *net_ns;
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};
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extern struct nsproxy init_nsproxy;
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int copy_namespaces(unsigned long flags, struct task_struct *tsk);
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void get_task_namespaces(struct task_struct *tsk);
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void free_nsproxy(struct nsproxy *ns);
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int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
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struct fs_struct *);
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static inline void put_nsproxy(struct nsproxy *ns)
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{
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if (atomic_dec_and_test(&ns->count)) {
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free_nsproxy(ns);
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}
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}
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static inline void exit_task_namespaces(struct task_struct *p)
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{
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struct nsproxy *ns = p->nsproxy;
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if (ns) {
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task_lock(p);
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p->nsproxy = NULL;
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task_unlock(p);
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put_nsproxy(ns);
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}
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}
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#ifdef CONFIG_CGROUP_NS
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int ns_cgroup_clone(struct task_struct *tsk);
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#else
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static inline int ns_cgroup_clone(struct task_struct *tsk) { return 0; }
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#endif
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#endif
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