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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,161 @@ | ||
| #include <linux/mount.h> | ||
| #include <linux/file.h> | ||
| #include <linux/fs.h> | ||
| #include <linux/proc_ns.h> | ||
| #include <linux/magic.h> | ||
| #include <linux/ktime.h> | ||
|
|
||
| static struct vfsmount *nsfs_mnt; | ||
|
|
||
| static const struct file_operations ns_file_operations = { | ||
| .llseek = no_llseek, | ||
| }; | ||
|
|
||
| static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) | ||
| { | ||
| struct inode *inode = dentry->d_inode; | ||
| const struct proc_ns_operations *ns_ops = dentry->d_fsdata; | ||
|
|
||
| return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]", | ||
| ns_ops->name, inode->i_ino); | ||
| } | ||
|
|
||
| static void ns_prune_dentry(struct dentry *dentry) | ||
| { | ||
| struct inode *inode = dentry->d_inode; | ||
| if (inode) { | ||
| struct ns_common *ns = inode->i_private; | ||
| atomic_long_set(&ns->stashed, 0); | ||
| } | ||
| } | ||
|
|
||
| const struct dentry_operations ns_dentry_operations = | ||
| { | ||
| .d_prune = ns_prune_dentry, | ||
| .d_delete = always_delete_dentry, | ||
| .d_dname = ns_dname, | ||
| }; | ||
|
|
||
| static void nsfs_evict(struct inode *inode) | ||
| { | ||
| struct ns_common *ns = inode->i_private; | ||
| clear_inode(inode); | ||
| ns->ops->put(ns); | ||
| } | ||
|
|
||
| void *ns_get_path(struct path *path, struct task_struct *task, | ||
| const struct proc_ns_operations *ns_ops) | ||
| { | ||
| struct vfsmount *mnt = mntget(nsfs_mnt); | ||
| struct qstr qname = { .name = "", }; | ||
| struct dentry *dentry; | ||
| struct inode *inode; | ||
| struct ns_common *ns; | ||
| unsigned long d; | ||
|
|
||
| again: | ||
| ns = ns_ops->get(task); | ||
| if (!ns) { | ||
| mntput(mnt); | ||
| return ERR_PTR(-ENOENT); | ||
| } | ||
| rcu_read_lock(); | ||
| d = atomic_long_read(&ns->stashed); | ||
| if (!d) | ||
| goto slow; | ||
| dentry = (struct dentry *)d; | ||
| if (!lockref_get_not_dead(&dentry->d_lockref)) | ||
| goto slow; | ||
| rcu_read_unlock(); | ||
| ns_ops->put(ns); | ||
| got_it: | ||
| path->mnt = mnt; | ||
| path->dentry = dentry; | ||
| return NULL; | ||
| slow: | ||
| rcu_read_unlock(); | ||
| inode = new_inode_pseudo(mnt->mnt_sb); | ||
| if (!inode) { | ||
| ns_ops->put(ns); | ||
| mntput(mnt); | ||
| return ERR_PTR(-ENOMEM); | ||
| } | ||
| inode->i_ino = ns->inum; | ||
| inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; | ||
| inode->i_flags |= S_IMMUTABLE; | ||
| inode->i_mode = S_IFREG | S_IRUGO; | ||
| inode->i_fop = &ns_file_operations; | ||
| inode->i_private = ns; | ||
|
|
||
| dentry = d_alloc_pseudo(mnt->mnt_sb, &qname); | ||
| if (!dentry) { | ||
| iput(inode); | ||
| mntput(mnt); | ||
| return ERR_PTR(-ENOMEM); | ||
| } | ||
| d_instantiate(dentry, inode); | ||
| dentry->d_fsdata = (void *)ns_ops; | ||
| d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry); | ||
| if (d) { | ||
| d_delete(dentry); /* make sure ->d_prune() does nothing */ | ||
| dput(dentry); | ||
| cpu_relax(); | ||
| goto again; | ||
| } | ||
| goto got_it; | ||
| } | ||
|
|
||
| int ns_get_name(char *buf, size_t size, struct task_struct *task, | ||
| const struct proc_ns_operations *ns_ops) | ||
| { | ||
| struct ns_common *ns; | ||
| int res = -ENOENT; | ||
| ns = ns_ops->get(task); | ||
| if (ns) { | ||
| res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum); | ||
| ns_ops->put(ns); | ||
| } | ||
| return res; | ||
| } | ||
|
|
||
| struct file *proc_ns_fget(int fd) | ||
| { | ||
| struct file *file; | ||
|
|
||
| file = fget(fd); | ||
| if (!file) | ||
| return ERR_PTR(-EBADF); | ||
|
|
||
| if (file->f_op != &ns_file_operations) | ||
| goto out_invalid; | ||
|
|
||
| return file; | ||
|
|
||
| out_invalid: | ||
| fput(file); | ||
| return ERR_PTR(-EINVAL); | ||
| } | ||
|
|
||
| static const struct super_operations nsfs_ops = { | ||
| .statfs = simple_statfs, | ||
| .evict_inode = nsfs_evict, | ||
| }; | ||
| static struct dentry *nsfs_mount(struct file_system_type *fs_type, | ||
| int flags, const char *dev_name, void *data) | ||
| { | ||
| return mount_pseudo(fs_type, "nsfs:", &nsfs_ops, | ||
| &ns_dentry_operations, NSFS_MAGIC); | ||
| } | ||
| static struct file_system_type nsfs = { | ||
| .name = "nsfs", | ||
| .mount = nsfs_mount, | ||
| .kill_sb = kill_anon_super, | ||
| }; | ||
|
|
||
| void __init nsfs_init(void) | ||
| { | ||
| nsfs_mnt = kern_mount(&nsfs); | ||
| if (IS_ERR(nsfs_mnt)) | ||
| panic("can't set nsfs up\n"); | ||
| nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER; | ||
| } |
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