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9a56493f69
Switch over uts 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/159644978167.604812.1773586504374412107.stgit@localhost.localdomain Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
91 lines
1.8 KiB
C
91 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_UTSNAME_H
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#define _LINUX_UTSNAME_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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#include <uapi/linux/utsname.h>
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enum uts_proc {
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UTS_PROC_OSTYPE,
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UTS_PROC_OSRELEASE,
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UTS_PROC_VERSION,
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UTS_PROC_HOSTNAME,
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UTS_PROC_DOMAINNAME,
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};
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struct user_namespace;
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extern struct user_namespace init_user_ns;
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struct uts_namespace {
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struct new_utsname name;
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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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} __randomize_layout;
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extern struct uts_namespace init_uts_ns;
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#ifdef CONFIG_UTS_NS
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static inline void get_uts_ns(struct uts_namespace *ns)
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{
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refcount_inc(&ns->ns.count);
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}
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extern struct uts_namespace *copy_utsname(unsigned long flags,
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struct user_namespace *user_ns, struct uts_namespace *old_ns);
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extern void free_uts_ns(struct uts_namespace *ns);
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static inline void put_uts_ns(struct uts_namespace *ns)
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{
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if (refcount_dec_and_test(&ns->ns.count))
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free_uts_ns(ns);
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}
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void uts_ns_init(void);
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#else
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static inline void get_uts_ns(struct uts_namespace *ns)
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{
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}
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static inline void put_uts_ns(struct uts_namespace *ns)
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{
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}
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static inline struct uts_namespace *copy_utsname(unsigned long flags,
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struct user_namespace *user_ns, struct uts_namespace *old_ns)
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{
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if (flags & CLONE_NEWUTS)
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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 void uts_ns_init(void)
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{
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}
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#endif
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#ifdef CONFIG_PROC_SYSCTL
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extern void uts_proc_notify(enum uts_proc proc);
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#else
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static inline void uts_proc_notify(enum uts_proc proc)
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{
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}
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#endif
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static inline struct new_utsname *utsname(void)
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{
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return ¤t->nsproxy->uts_ns->name;
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}
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static inline struct new_utsname *init_utsname(void)
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{
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return &init_uts_ns.name;
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}
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extern struct rw_semaphore uts_sem;
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#endif /* _LINUX_UTSNAME_H */
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