| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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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/refcount.h> |
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| 6 | #include <linux/spinlock.h> |
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| 7 | #include <linux/sched.h> |
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| 8 | |
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| 9 | struct mnt_namespace; |
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| 10 | struct uts_namespace; |
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| 11 | struct ipc_namespace; |
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| 12 | struct pid_namespace; |
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| 13 | struct cgroup_namespace; |
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| 14 | struct fs_struct; |
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| 15 | |
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| 16 | /* |
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| 17 | * A structure to contain pointers to all per-process |
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| 18 | * namespaces - fs (mount), uts, network, sysvipc, etc. |
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| 19 | * |
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| 20 | * The pid namespace is an exception -- it's accessed using |
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| 21 | * task_active_pid_ns. The pid namespace here is the |
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| 22 | * namespace that children will use. |
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| 23 | * |
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| 24 | * 'count' is the number of tasks holding a reference. |
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| 25 | * The count for each namespace, then, will be the number |
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| 26 | * of nsproxies pointing to it, not the number of tasks. |
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| 27 | * |
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| 28 | * The nsproxy is shared by tasks which share all namespaces. |
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| 29 | * As soon as a single namespace is cloned or unshared, the |
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| 30 | * nsproxy is copied. |
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| 31 | */ |
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| 32 | struct nsproxy { |
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| 33 | refcount_t count; |
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| 34 | struct uts_namespace *uts_ns; |
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| 35 | struct ipc_namespace *ipc_ns; |
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| 36 | struct mnt_namespace *mnt_ns; |
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| 37 | struct pid_namespace *pid_ns_for_children; |
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| 38 | struct net *net_ns; |
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| 39 | struct time_namespace *time_ns; |
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| 40 | struct time_namespace *time_ns_for_children; |
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| 41 | struct cgroup_namespace *cgroup_ns; |
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| 42 | }; |
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| 43 | extern struct nsproxy init_nsproxy; |
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| 44 | |
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| 45 | #define to_ns_common(__ns) \ |
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| 46 | _Generic((__ns), \ |
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| 47 | struct cgroup_namespace *: &(__ns->ns), \ |
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| 48 | struct ipc_namespace *: &(__ns->ns), \ |
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| 49 | struct net *: &(__ns->ns), \ |
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| 50 | struct pid_namespace *: &(__ns->ns), \ |
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| 51 | struct mnt_namespace *: &(__ns->ns), \ |
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| 52 | struct time_namespace *: &(__ns->ns), \ |
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| 53 | struct user_namespace *: &(__ns->ns), \ |
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| 54 | struct uts_namespace *: &(__ns->ns)) |
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| 55 | |
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| 56 | /* |
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| 57 | * A structure to encompass all bits needed to install |
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| 58 | * a partial or complete new set of namespaces. |
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| 59 | * |
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| 60 | * If a new user namespace is requested cred will |
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| 61 | * point to a modifiable set of credentials. If a pointer |
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| 62 | * to a modifiable set is needed nsset_cred() must be |
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| 63 | * used and tested. |
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| 64 | */ |
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| 65 | struct nsset { |
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| 66 | unsigned flags; |
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| 67 | struct nsproxy *nsproxy; |
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| 68 | struct fs_struct *fs; |
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| 69 | const struct cred *cred; |
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| 70 | }; |
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| 71 | |
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| 72 | static inline struct cred *nsset_cred(struct nsset *set) |
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| 73 | { |
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| 74 | if (set->flags & CLONE_NEWUSER) |
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| 75 | return (struct cred *)set->cred; |
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| 76 | |
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| 77 | return NULL; |
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| 78 | } |
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| 79 | |
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| 80 | /* |
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| 81 | * the namespaces access rules are: |
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| 82 | * |
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| 83 | * 1. only current task is allowed to change tsk->nsproxy pointer or |
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| 84 | * any pointer on the nsproxy itself. Current must hold the task_lock |
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| 85 | * when changing tsk->nsproxy. |
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| 86 | * |
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| 87 | * 2. when accessing (i.e. reading) current task's namespaces - no |
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| 88 | * precautions should be taken - just dereference the pointers |
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| 89 | * |
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| 90 | * 3. the access to other task namespaces is performed like this |
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| 91 | * task_lock(task); |
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| 92 | * nsproxy = task->nsproxy; |
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| 93 | * if (nsproxy != NULL) { |
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| 94 | * / * |
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| 95 | * * work with the namespaces here |
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| 96 | * * e.g. get the reference on one of them |
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| 97 | * * / |
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| 98 | * } / * |
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| 99 | * * NULL task->nsproxy means that this task is |
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| 100 | * * almost dead (zombie) |
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| 101 | * * / |
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| 102 | * task_unlock(task); |
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| 103 | * |
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| 104 | */ |
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| 105 | |
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| 106 | int copy_namespaces(unsigned long flags, struct task_struct *tsk); |
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| 107 | void exit_task_namespaces(struct task_struct *tsk); |
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| 108 | void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); |
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| 109 | int exec_task_namespaces(void); |
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| 110 | void free_nsproxy(struct nsproxy *ns); |
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| 111 | int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, |
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| 112 | struct cred *, struct fs_struct *); |
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| 113 | int __init nsproxy_cache_init(void); |
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| 114 | |
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| 115 | static inline void put_nsproxy(struct nsproxy *ns) |
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| 116 | { |
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| 117 | if (refcount_dec_and_test(r: &ns->count)) |
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| 118 | free_nsproxy(ns); |
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| 119 | } |
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| 120 | |
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| 121 | static inline void get_nsproxy(struct nsproxy *ns) |
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| 122 | { |
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| 123 | refcount_inc(r: &ns->count); |
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| 124 | } |
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| 125 | |
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| 126 | DEFINE_FREE(put_nsproxy, struct nsproxy *, if (_T) put_nsproxy(_T)) |
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| 127 | |
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| 128 | #endif |
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| 129 | |
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