| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef _LINUX_NSPROXY_H |
| 3 | #define _LINUX_NSPROXY_H |
| 4 | |
| 5 | #include <linux/spinlock.h> |
| 6 | #include <linux/sched.h> |
| 7 | |
| 8 | struct mnt_namespace; |
| 9 | struct uts_namespace; |
| 10 | struct ipc_namespace; |
| 11 | struct pid_namespace; |
| 12 | struct cgroup_namespace; |
| 13 | struct fs_struct; |
| 14 | |
| 15 | /* |
| 16 | * A structure to contain pointers to all per-process |
| 17 | * namespaces - fs (mount), uts, network, sysvipc, etc. |
| 18 | * |
| 19 | * The pid namespace is an exception -- it's accessed using |
| 20 | * task_active_pid_ns. The pid namespace here is the |
| 21 | * namespace that children will use. |
| 22 | * |
| 23 | * 'count' is the number of tasks holding a reference. |
| 24 | * The count for each namespace, then, will be the number |
| 25 | * of nsproxies pointing to it, not the number of tasks. |
| 26 | * |
| 27 | * The nsproxy is shared by tasks which share all namespaces. |
| 28 | * As soon as a single namespace is cloned or unshared, the |
| 29 | * nsproxy is copied. |
| 30 | */ |
| 31 | struct nsproxy { |
| 32 | atomic_t count; |
| 33 | struct uts_namespace *uts_ns; |
| 34 | struct ipc_namespace *ipc_ns; |
| 35 | struct mnt_namespace *mnt_ns; |
| 36 | struct pid_namespace *pid_ns_for_children; |
| 37 | struct net *net_ns; |
| 38 | struct time_namespace *time_ns; |
| 39 | struct time_namespace *time_ns_for_children; |
| 40 | struct cgroup_namespace *cgroup_ns; |
| 41 | }; |
| 42 | extern struct nsproxy init_nsproxy; |
| 43 | |
| 44 | /* |
| 45 | * A structure to encompass all bits needed to install |
| 46 | * a partial or complete new set of namespaces. |
| 47 | * |
| 48 | * If a new user namespace is requested cred will |
| 49 | * point to a modifiable set of credentials. If a pointer |
| 50 | * to a modifiable set is needed nsset_cred() must be |
| 51 | * used and tested. |
| 52 | */ |
| 53 | struct nsset { |
| 54 | unsigned flags; |
| 55 | struct nsproxy *nsproxy; |
| 56 | struct fs_struct *fs; |
| 57 | const struct cred *cred; |
| 58 | }; |
| 59 | |
| 60 | static inline struct cred *nsset_cred(struct nsset *set) |
| 61 | { |
| 62 | if (set->flags & CLONE_NEWUSER) |
| 63 | return (struct cred *)set->cred; |
| 64 | |
| 65 | return NULL; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * the namespaces access rules are: |
| 70 | * |
| 71 | * 1. only current task is allowed to change tsk->nsproxy pointer or |
| 72 | * any pointer on the nsproxy itself. Current must hold the task_lock |
| 73 | * when changing tsk->nsproxy. |
| 74 | * |
| 75 | * 2. when accessing (i.e. reading) current task's namespaces - no |
| 76 | * precautions should be taken - just dereference the pointers |
| 77 | * |
| 78 | * 3. the access to other task namespaces is performed like this |
| 79 | * task_lock(task); |
| 80 | * nsproxy = task->nsproxy; |
| 81 | * if (nsproxy != NULL) { |
| 82 | * / * |
| 83 | * * work with the namespaces here |
| 84 | * * e.g. get the reference on one of them |
| 85 | * * / |
| 86 | * } / * |
| 87 | * * NULL task->nsproxy means that this task is |
| 88 | * * almost dead (zombie) |
| 89 | * * / |
| 90 | * task_unlock(task); |
| 91 | * |
| 92 | */ |
| 93 | |
| 94 | int copy_namespaces(unsigned long flags, struct task_struct *tsk); |
| 95 | void exit_task_namespaces(struct task_struct *tsk); |
| 96 | void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); |
| 97 | void free_nsproxy(struct nsproxy *ns); |
| 98 | int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **, |
| 99 | struct cred *, struct fs_struct *); |
| 100 | int __init nsproxy_cache_init(void); |
| 101 | |
| 102 | static inline void put_nsproxy(struct nsproxy *ns) |
| 103 | { |
| 104 | if (atomic_dec_and_test(&ns->count)) { |
| 105 | free_nsproxy(ns); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | static inline void get_nsproxy(struct nsproxy *ns) |
| 110 | { |
| 111 | atomic_inc(&ns->count); |
| 112 | } |
| 113 | |
| 114 | #endif |