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>
86 lines
1.9 KiB
C
86 lines
1.9 KiB
C
#ifndef _LINUX_USER_NAMESPACE_H
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#define _LINUX_USER_NAMESPACE_H
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#include <linux/kref.h>
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#include <linux/nsproxy.h>
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#include <linux/sched.h>
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#include <linux/err.h>
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#define UID_GID_MAP_MAX_EXTENTS 5
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struct uid_gid_map { /* 64 bytes -- 1 cache line */
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u32 nr_extents;
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struct uid_gid_extent {
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u32 first;
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u32 lower_first;
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u32 count;
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} extent[UID_GID_MAP_MAX_EXTENTS];
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};
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struct user_namespace {
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struct uid_gid_map uid_map;
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struct uid_gid_map gid_map;
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struct uid_gid_map projid_map;
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struct kref kref;
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struct user_namespace *parent;
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kuid_t owner;
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kgid_t group;
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unsigned int proc_inum;
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};
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extern struct user_namespace init_user_ns;
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#ifdef CONFIG_USER_NS
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static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
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{
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if (ns)
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kref_get(&ns->kref);
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return ns;
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}
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extern int create_user_ns(struct cred *new);
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extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
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extern void free_user_ns(struct kref *kref);
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static inline void put_user_ns(struct user_namespace *ns)
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{
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if (ns)
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kref_put(&ns->kref, free_user_ns);
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}
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struct seq_operations;
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extern struct seq_operations proc_uid_seq_operations;
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extern struct seq_operations proc_gid_seq_operations;
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extern struct seq_operations proc_projid_seq_operations;
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extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
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extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
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extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
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#else
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static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
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{
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return &init_user_ns;
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}
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static inline int create_user_ns(struct cred *new)
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{
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return -EINVAL;
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}
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static inline int unshare_userns(unsigned long unshare_flags,
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struct cred **new_cred)
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{
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if (unshare_flags & CLONE_NEWUSER)
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return -EINVAL;
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return 0;
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}
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static inline void put_user_ns(struct user_namespace *ns)
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{
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}
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#endif
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#endif /* _LINUX_USER_H */
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