xref: /linux-6.15/include/linux/time_namespace.h (revision aaa3e7fb) 
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_TIMENS_H
3 #define _LINUX_TIMENS_H
4 
5 
6 #include <linux/sched.h>
7 #include <linux/kref.h>
8 #include <linux/nsproxy.h>
9 #include <linux/ns_common.h>
10 #include <linux/err.h>
11 
12 struct user_namespace;
13 extern struct user_namespace init_user_ns;
14 
15 struct timens_offsets {
16 	struct timespec64 monotonic;
17 	struct timespec64 boottime;
18 };
19 
20 struct time_namespace {
21 	struct kref		kref;
22 	struct user_namespace	*user_ns;
23 	struct ucounts		*ucounts;
24 	struct ns_common	ns;
25 	struct timens_offsets	offsets;
26 	struct page		*vvar_page;
27 	/* If set prevents changing offsets after any task joined namespace. */
28 	bool			frozen_offsets;
29 } __randomize_layout;
30 
31 extern struct time_namespace init_time_ns;
32 
33 #ifdef CONFIG_TIME_NS
34 extern int vdso_join_timens(struct task_struct *task,
35 			    struct time_namespace *ns);
36 extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
37 
38 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
39 {
40 	kref_get(&ns->kref);
41 	return ns;
42 }
43 
44 struct time_namespace *copy_time_ns(unsigned long flags,
45 				    struct user_namespace *user_ns,
46 				    struct time_namespace *old_ns);
47 void free_time_ns(struct kref *kref);
48 int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
49 struct vdso_data *arch_get_vdso_data(void *vvar_page);
50 
51 static inline void put_time_ns(struct time_namespace *ns)
52 {
53 	kref_put(&ns->kref, free_time_ns);
54 }
55 
56 void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
57 
58 struct proc_timens_offset {
59 	int			clockid;
60 	struct timespec64	val;
61 };
62 
63 int proc_timens_set_offset(struct file *file, struct task_struct *p,
64 			   struct proc_timens_offset *offsets, int n);
65 
66 static inline void timens_add_monotonic(struct timespec64 *ts)
67 {
68 	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
69 
70 	*ts = timespec64_add(*ts, ns_offsets->monotonic);
71 }
72 
73 static inline void timens_add_boottime(struct timespec64 *ts)
74 {
75 	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
76 
77 	*ts = timespec64_add(*ts, ns_offsets->boottime);
78 }
79 
80 ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
81 				struct timens_offsets *offsets);
82 
83 static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
84 {
85 	struct time_namespace *ns = current->nsproxy->time_ns;
86 
87 	if (likely(ns == &init_time_ns))
88 		return tim;
89 
90 	return do_timens_ktime_to_host(clockid, tim, &ns->offsets);
91 }
92 
93 #else
94 static inline int vdso_join_timens(struct task_struct *task,
95 				   struct time_namespace *ns)
96 {
97 	return 0;
98 }
99 
100 static inline void timens_commit(struct task_struct *tsk,
101 				 struct time_namespace *ns)
102 {
103 }
104 
105 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
106 {
107 	return NULL;
108 }
109 
110 static inline void put_time_ns(struct time_namespace *ns)
111 {
112 }
113 
114 static inline
115 struct time_namespace *copy_time_ns(unsigned long flags,
116 				    struct user_namespace *user_ns,
117 				    struct time_namespace *old_ns)
118 {
119 	if (flags & CLONE_NEWTIME)
120 		return ERR_PTR(-EINVAL);
121 
122 	return old_ns;
123 }
124 
125 static inline int timens_on_fork(struct nsproxy *nsproxy,
126 				 struct task_struct *tsk)
127 {
128 	return 0;
129 }
130 
131 static inline void timens_add_monotonic(struct timespec64 *ts) { }
132 static inline void timens_add_boottime(struct timespec64 *ts) { }
133 static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
134 {
135 	return tim;
136 }
137 #endif
138 
139 #endif /* _LINUX_TIMENS_H */
140