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28c41efd08
Switch over time namespaces to use the newly introduced common lifetime counter. Currently every namespace type has its own lifetime counter which is stored in the specific namespace struct. The lifetime counters are used identically for all namespaces types. Namespaces may of course have additional unrelated counters and these are not altered. This introduces a common lifetime counter into struct ns_common. The ns_common struct encompasses information that all namespaces share. That should include the lifetime counter since its common for all of them. It also allows us to unify the type of the counters across all namespaces. Most of them use refcount_t but one uses atomic_t and at least one uses kref. Especially the last one doesn't make much sense since it's just a wrapper around refcount_t since 2016 and actually complicates cleanup operations by having to use container_of() to cast the correct namespace struct out of struct ns_common. Having the lifetime counter for the namespaces in one place reduces maintenance cost. Not just because after switching all namespaces over we will have removed more code than we added but also because the logic is more easily understandable and we indicate to the user that the basic lifetime requirements for all namespaces are currently identical. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/159644982033.604812.9406853013011123238.stgit@localhost.localdomain Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
139 lines
3.3 KiB
C
139 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_TIMENS_H
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#define _LINUX_TIMENS_H
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#include <linux/sched.h>
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#include <linux/nsproxy.h>
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#include <linux/ns_common.h>
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#include <linux/err.h>
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struct user_namespace;
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extern struct user_namespace init_user_ns;
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struct timens_offsets {
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struct timespec64 monotonic;
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struct timespec64 boottime;
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};
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struct time_namespace {
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struct user_namespace *user_ns;
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struct ucounts *ucounts;
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struct ns_common ns;
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struct timens_offsets offsets;
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struct page *vvar_page;
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/* If set prevents changing offsets after any task joined namespace. */
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bool frozen_offsets;
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} __randomize_layout;
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extern struct time_namespace init_time_ns;
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#ifdef CONFIG_TIME_NS
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extern int vdso_join_timens(struct task_struct *task,
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struct time_namespace *ns);
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extern void timens_commit(struct task_struct *tsk, struct time_namespace *ns);
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static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
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{
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refcount_inc(&ns->ns.count);
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return ns;
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}
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struct time_namespace *copy_time_ns(unsigned long flags,
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struct user_namespace *user_ns,
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struct time_namespace *old_ns);
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void free_time_ns(struct time_namespace *ns);
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int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk);
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struct vdso_data *arch_get_vdso_data(void *vvar_page);
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static inline void put_time_ns(struct time_namespace *ns)
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{
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if (refcount_dec_and_test(&ns->ns.count))
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free_time_ns(ns);
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}
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void proc_timens_show_offsets(struct task_struct *p, struct seq_file *m);
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struct proc_timens_offset {
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int clockid;
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struct timespec64 val;
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};
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int proc_timens_set_offset(struct file *file, struct task_struct *p,
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struct proc_timens_offset *offsets, int n);
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static inline void timens_add_monotonic(struct timespec64 *ts)
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{
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struct timens_offsets *ns_offsets = ¤t->nsproxy->time_ns->offsets;
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*ts = timespec64_add(*ts, ns_offsets->monotonic);
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}
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static inline void timens_add_boottime(struct timespec64 *ts)
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{
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struct timens_offsets *ns_offsets = ¤t->nsproxy->time_ns->offsets;
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*ts = timespec64_add(*ts, ns_offsets->boottime);
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}
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ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
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struct timens_offsets *offsets);
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static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
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{
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struct time_namespace *ns = current->nsproxy->time_ns;
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if (likely(ns == &init_time_ns))
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return tim;
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return do_timens_ktime_to_host(clockid, tim, &ns->offsets);
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}
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#else
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static inline int vdso_join_timens(struct task_struct *task,
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struct time_namespace *ns)
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{
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return 0;
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}
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static inline void timens_commit(struct task_struct *tsk,
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struct time_namespace *ns)
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{
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}
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static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
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{
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return NULL;
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}
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static inline void put_time_ns(struct time_namespace *ns)
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{
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}
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static inline
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struct time_namespace *copy_time_ns(unsigned long flags,
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struct user_namespace *user_ns,
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struct time_namespace *old_ns)
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{
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if (flags & CLONE_NEWTIME)
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return ERR_PTR(-EINVAL);
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return old_ns;
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}
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static inline int timens_on_fork(struct nsproxy *nsproxy,
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struct task_struct *tsk)
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{
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return 0;
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}
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static inline void timens_add_monotonic(struct timespec64 *ts) { }
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static inline void timens_add_boottime(struct timespec64 *ts) { }
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static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
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{
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return tim;
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}
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#endif
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#endif /* _LINUX_TIMENS_H */
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