| 1 |
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| 2 | #ifndef _LINUX_NSPROXY_H
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| 3 | #define _LINUX_NSPROXY_H
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| 4 |
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| 5 | #include <linux/spinlock.h>
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| 6 | #include <linux/sched.h>
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| 7 |
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| 8 | struct mnt_namespace;
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| 9 | struct uts_namespace;
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| 10 | struct ipc_namespace;
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| 11 | struct pid_namespace;
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| 12 | struct cgroup_namespace;
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| 13 | struct fs_struct;
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| 14 |
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| 15 | |
| 16 | * A structure to contain pointers to all per-process
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| 17 | * namespaces - fs (mount), uts, network, sysvipc, etc.
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| 18 | *
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| 19 | * The pid namespace is an exception -- it's accessed using
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| 20 | * task_active_pid_ns. The pid namespace here is the
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| 21 | * namespace that children will use.
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| 22 | *
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| 23 | * 'count' is the number of tasks holding a reference.
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| 24 | * The count for each namespace, then, will be the number
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| 25 | * of nsproxies pointing to it, not the number of tasks.
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| 26 | *
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| 27 | * The nsproxy is shared by tasks which share all namespaces.
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| 28 | * As soon as a single namespace is cloned or unshared, the
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| 29 | * nsproxy is copied.
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| 30 |
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| 31 | struct nsproxy {
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| 32 | refcount_t count;
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| 33 | struct uts_namespace *uts_ns;
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| 34 | struct ipc_namespace *ipc_ns;
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| 35 | struct mnt_namespace *mnt_ns;
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| 36 | struct pid_namespace *pid_ns_for_children;
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| 37 | struct net *net_ns;
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| 38 | struct time_namespace *time_ns;
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| 39 | struct time_namespace *time_ns_for_children;
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| 40 | struct cgroup_namespace *cgroup_ns;
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| 41 | };
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| 42 | extern struct nsproxy init_nsproxy;
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| 43 |
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| 44 | |
| 45 | * A structure to encompass all bits needed to install
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| 46 | * a partial or complete new set of namespaces.
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| 47 | *
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| 48 | * If a new user namespace is requested cred will
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| 49 | * point to a modifiable set of credentials. If a pointer
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| 50 | * to a modifiable set is needed nsset_cred() must be
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| 51 | * used and tested.
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| 52 |
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| 53 | struct nsset {
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| 54 | unsigned flags;
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| 55 | struct nsproxy *nsproxy;
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| 56 | struct fs_struct *fs;
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| 57 | const struct cred *cred;
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| 58 | };
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| 59 |
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| 60 | static inline struct cred *nsset_cred(struct nsset *set)
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| 61 | {
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| 62 | if (set->flags & CLONE_NEWUSER)
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| 63 | return (struct cred *)set->cred;
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| 64 |
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| 65 | return NULL;
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| 66 | }
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| 67 |
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| 68 | |
| 69 | * the namespaces access rules are:
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| 70 | *
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| 71 | * 1. only current task is allowed to change tsk->nsproxy pointer or
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| 72 | * any pointer on the nsproxy itself. Current must hold the task_lock
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| 73 | * when changing tsk->nsproxy.
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| 74 | *
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| 75 | * 2. when accessing (i.e. reading) current task's namespaces - no
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| 76 | * precautions should be taken - just dereference the pointers
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| 77 | *
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| 78 | * 3. the access to other task namespaces is performed like this
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| 79 | * task_lock(task);
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| 80 | * nsproxy = task->nsproxy;
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| 81 | * if (nsproxy != NULL) {
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| 82 | * / *
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| 83 | * * work with the namespaces here
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| 84 | * * e.g. get the reference on one of them
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| 85 | * * /
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| 86 | * } / *
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| 87 | * * NULL task->nsproxy means that this task is
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| 88 | * * almost dead (zombie)
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| 89 | * * /
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| 90 | * task_unlock(task);
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| 91 | *
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| 92 |
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| 93 |
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| 94 | int copy_namespaces(unsigned long flags, struct task_struct *tsk);
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| 95 | void exit_task_namespaces(struct task_struct *tsk);
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| 96 | void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
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| 97 | int exec_task_namespaces(void);
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| 98 | void free_nsproxy(struct nsproxy *ns);
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| 99 | int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
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| 100 | struct cred *, struct fs_struct *);
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| 101 | int __init nsproxy_cache_init(void);
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| 102 |
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| 103 | static inline void put_nsproxy(struct nsproxy *ns)
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| 104 | {
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| 105 | if (refcount_dec_and_test(&ns->count))
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| 106 | free_nsproxy(ns);
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| 107 | }
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| 108 |
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| 109 | static inline void get_nsproxy(struct nsproxy *ns)
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| 110 | {
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| 111 | refcount_inc(&ns->count);
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| 112 | }
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| 113 |
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| 114 | #endif
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