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98f842e675
Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
84 lines
1.6 KiB
C
84 lines
1.6 KiB
C
#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/kref.h>
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#include <linux/nsproxy.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 kref kref;
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struct new_utsname name;
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struct user_namespace *user_ns;
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unsigned int proc_inum;
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};
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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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kref_get(&ns->kref);
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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 kref *kref);
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static inline void put_uts_ns(struct uts_namespace *ns)
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{
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kref_put(&ns->kref, free_uts_ns);
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}
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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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#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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