1 #include <linux/mount.h>
2 #include <linux/file.h>
4 #include <linux/proc_ns.h>
5 #include <linux/magic.h>
6 #include <linux/ktime.h>
7 #include <linux/seq_file.h>
8 #include <linux/user_namespace.h>
9 #include <linux/nsfs.h>
11 static struct vfsmount *nsfs_mnt;
13 static long ns_ioctl(struct file *filp, unsigned int ioctl,
15 static const struct file_operations ns_file_operations = {
17 .unlocked_ioctl = ns_ioctl,
20 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
22 struct inode *inode = d_inode(dentry);
23 const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
25 return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
26 ns_ops->name, inode->i_ino);
29 static void ns_prune_dentry(struct dentry *dentry)
31 struct inode *inode = d_inode(dentry);
33 struct ns_common *ns = inode->i_private;
34 atomic_long_set(&ns->stashed, 0);
38 const struct dentry_operations ns_dentry_operations =
40 .d_prune = ns_prune_dentry,
41 .d_delete = always_delete_dentry,
45 static void nsfs_evict(struct inode *inode)
47 struct ns_common *ns = inode->i_private;
52 static void *__ns_get_path(struct path *path, struct ns_common *ns)
54 struct vfsmount *mnt = mntget(nsfs_mnt);
55 struct qstr qname = { .name = "", };
56 struct dentry *dentry;
61 d = atomic_long_read(&ns->stashed);
64 dentry = (struct dentry *)d;
65 if (!lockref_get_not_dead(&dentry->d_lockref))
71 path->dentry = dentry;
75 inode = new_inode_pseudo(mnt->mnt_sb);
79 return ERR_PTR(-ENOMEM);
81 inode->i_ino = ns->inum;
82 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
83 inode->i_flags |= S_IMMUTABLE;
84 inode->i_mode = S_IFREG | S_IRUGO;
85 inode->i_fop = &ns_file_operations;
86 inode->i_private = ns;
88 dentry = d_alloc_pseudo(mnt->mnt_sb, &qname);
92 return ERR_PTR(-ENOMEM);
94 d_instantiate(dentry, inode);
95 dentry->d_fsdata = (void *)ns->ops;
96 d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
98 d_delete(dentry); /* make sure ->d_prune() does nothing */
102 return ERR_PTR(-EAGAIN);
107 void *ns_get_path(struct path *path, struct task_struct *task,
108 const struct proc_ns_operations *ns_ops)
110 struct ns_common *ns;
114 ns = ns_ops->get(task);
116 return ERR_PTR(-ENOENT);
118 ret = __ns_get_path(path, ns);
119 if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN)
124 static int open_related_ns(struct ns_common *ns,
125 struct ns_common *(*get_ns)(struct ns_common *ns))
127 struct path path = {};
132 fd = get_unused_fd_flags(O_CLOEXEC);
137 struct ns_common *relative;
139 relative = get_ns(ns);
140 if (IS_ERR(relative)) {
142 return PTR_ERR(relative);
145 err = __ns_get_path(&path, relative);
146 if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN)
155 f = dentry_open(&path, O_RDONLY, current_cred());
166 static long ns_ioctl(struct file *filp, unsigned int ioctl,
169 struct ns_common *ns = get_proc_ns(file_inode(filp));
173 return open_related_ns(ns, ns_get_owner);
175 if (!ns->ops->get_parent)
177 return open_related_ns(ns, ns->ops->get_parent);
183 int ns_get_name(char *buf, size_t size, struct task_struct *task,
184 const struct proc_ns_operations *ns_ops)
186 struct ns_common *ns;
188 ns = ns_ops->get(task);
190 res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum);
196 struct file *proc_ns_fget(int fd)
202 return ERR_PTR(-EBADF);
204 if (file->f_op != &ns_file_operations)
211 return ERR_PTR(-EINVAL);
214 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
216 struct inode *inode = d_inode(dentry);
217 const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
219 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
223 static const struct super_operations nsfs_ops = {
224 .statfs = simple_statfs,
225 .evict_inode = nsfs_evict,
226 .show_path = nsfs_show_path,
228 static struct dentry *nsfs_mount(struct file_system_type *fs_type,
229 int flags, const char *dev_name, void *data)
231 return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
232 &ns_dentry_operations, NSFS_MAGIC);
234 static struct file_system_type nsfs = {
237 .kill_sb = kill_anon_super,
240 void __init nsfs_init(void)
242 nsfs_mnt = kern_mount(&nsfs);
243 if (IS_ERR(nsfs_mnt))
244 panic("can't set nsfs up\n");
245 nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;