e51db73532
Rely on the fact that another flavor of the filesystem is already mounted and do not rely on state in the user namespace. Verify that the mounted filesystem is not covered in any significant way. I would love to verify that the previously mounted filesystem has no mounts on top but there are at least the directories /proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly for other filesystems to mount on top of. Refactor the test into a function named fs_fully_visible and call that function from the mount routines of proc and sysfs. This makes this test local to the filesystems involved and the results current of when the mounts take place, removing a weird threading of the user namespace, the mount namespace and the filesystems themselves. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
85 lines
2 KiB
C
85 lines
2 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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atomic_t count;
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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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atomic_inc(&ns->count);
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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 user_namespace *ns);
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static inline void put_user_ns(struct user_namespace *ns)
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{
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if (ns && atomic_dec_and_test(&ns->count))
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free_user_ns(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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