blob: 80fdfad7c215c1f60693557625bcc3d852ad8c2f [file] [log] [blame]
Al Viroe149ed22014-11-01 10:57:28 -04001#include <linux/mount.h>
2#include <linux/file.h>
3#include <linux/fs.h>
4#include <linux/proc_ns.h>
5#include <linux/magic.h>
6#include <linux/ktime.h>
Eric W. Biederman75509fd2015-05-24 12:49:04 -05007#include <linux/seq_file.h>
Andrey Vagin67867412016-09-06 00:47:14 -07008#include <linux/user_namespace.h>
9#include <linux/nsfs.h>
Al Viroe149ed22014-11-01 10:57:28 -040010
11static struct vfsmount *nsfs_mnt;
12
Andrey Vagin67867412016-09-06 00:47:14 -070013static long ns_ioctl(struct file *filp, unsigned int ioctl,
14 unsigned long arg);
Al Viroe149ed22014-11-01 10:57:28 -040015static const struct file_operations ns_file_operations = {
16 .llseek = no_llseek,
Andrey Vagin67867412016-09-06 00:47:14 -070017 .unlocked_ioctl = ns_ioctl,
Al Viroe149ed22014-11-01 10:57:28 -040018};
19
20static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
21{
David Howells75c3cfa2015-03-17 22:26:12 +000022 struct inode *inode = d_inode(dentry);
Al Viroe149ed22014-11-01 10:57:28 -040023 const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
24
25 return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
26 ns_ops->name, inode->i_ino);
27}
28
29static void ns_prune_dentry(struct dentry *dentry)
30{
David Howells75c3cfa2015-03-17 22:26:12 +000031 struct inode *inode = d_inode(dentry);
Al Viroe149ed22014-11-01 10:57:28 -040032 if (inode) {
33 struct ns_common *ns = inode->i_private;
34 atomic_long_set(&ns->stashed, 0);
35 }
36}
37
38const struct dentry_operations ns_dentry_operations =
39{
40 .d_prune = ns_prune_dentry,
41 .d_delete = always_delete_dentry,
42 .d_dname = ns_dname,
43};
44
45static void nsfs_evict(struct inode *inode)
46{
47 struct ns_common *ns = inode->i_private;
48 clear_inode(inode);
49 ns->ops->put(ns);
50}
51
Andrey Vagin67867412016-09-06 00:47:14 -070052static void *__ns_get_path(struct path *path, struct ns_common *ns)
Al Viroe149ed22014-11-01 10:57:28 -040053{
Eric W. Biederman213b0672016-09-22 19:39:20 -050054 struct vfsmount *mnt = nsfs_mnt;
Al Viroe149ed22014-11-01 10:57:28 -040055 struct qstr qname = { .name = "", };
56 struct dentry *dentry;
57 struct inode *inode;
Al Viroe149ed22014-11-01 10:57:28 -040058 unsigned long d;
59
Al Viroe149ed22014-11-01 10:57:28 -040060 rcu_read_lock();
61 d = atomic_long_read(&ns->stashed);
62 if (!d)
63 goto slow;
64 dentry = (struct dentry *)d;
65 if (!lockref_get_not_dead(&dentry->d_lockref))
66 goto slow;
67 rcu_read_unlock();
Andrey Vagin67867412016-09-06 00:47:14 -070068 ns->ops->put(ns);
Al Viroe149ed22014-11-01 10:57:28 -040069got_it:
Eric W. Biederman213b0672016-09-22 19:39:20 -050070 path->mnt = mntget(mnt);
Al Viroe149ed22014-11-01 10:57:28 -040071 path->dentry = dentry;
72 return NULL;
73slow:
74 rcu_read_unlock();
75 inode = new_inode_pseudo(mnt->mnt_sb);
76 if (!inode) {
Andrey Vagin67867412016-09-06 00:47:14 -070077 ns->ops->put(ns);
Al Viroe149ed22014-11-01 10:57:28 -040078 return ERR_PTR(-ENOMEM);
79 }
80 inode->i_ino = ns->inum;
Deepa Dinamani078cd822016-09-14 07:48:04 -070081 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
Al Viroe149ed22014-11-01 10:57:28 -040082 inode->i_flags |= S_IMMUTABLE;
83 inode->i_mode = S_IFREG | S_IRUGO;
84 inode->i_fop = &ns_file_operations;
85 inode->i_private = ns;
86
87 dentry = d_alloc_pseudo(mnt->mnt_sb, &qname);
88 if (!dentry) {
89 iput(inode);
Al Viroe149ed22014-11-01 10:57:28 -040090 return ERR_PTR(-ENOMEM);
91 }
92 d_instantiate(dentry, inode);
Cong Wangdaaa81c2017-04-19 15:11:00 -070093 dentry->d_flags |= DCACHE_RCUACCESS;
Andrey Vagin67867412016-09-06 00:47:14 -070094 dentry->d_fsdata = (void *)ns->ops;
Al Viroe149ed22014-11-01 10:57:28 -040095 d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
96 if (d) {
97 d_delete(dentry); /* make sure ->d_prune() does nothing */
98 dput(dentry);
99 cpu_relax();
Andrey Vagin67867412016-09-06 00:47:14 -0700100 return ERR_PTR(-EAGAIN);
Al Viroe149ed22014-11-01 10:57:28 -0400101 }
102 goto got_it;
103}
104
Andrey Vagin67867412016-09-06 00:47:14 -0700105void *ns_get_path(struct path *path, struct task_struct *task,
106 const struct proc_ns_operations *ns_ops)
107{
108 struct ns_common *ns;
109 void *ret;
110
111again:
112 ns = ns_ops->get(task);
113 if (!ns)
114 return ERR_PTR(-ENOENT);
115
116 ret = __ns_get_path(path, ns);
117 if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN)
118 goto again;
119 return ret;
120}
121
122static int open_related_ns(struct ns_common *ns,
123 struct ns_common *(*get_ns)(struct ns_common *ns))
124{
125 struct path path = {};
126 struct file *f;
127 void *err;
128 int fd;
129
130 fd = get_unused_fd_flags(O_CLOEXEC);
131 if (fd < 0)
132 return fd;
133
134 while (1) {
135 struct ns_common *relative;
136
137 relative = get_ns(ns);
138 if (IS_ERR(relative)) {
139 put_unused_fd(fd);
140 return PTR_ERR(relative);
141 }
142
143 err = __ns_get_path(&path, relative);
144 if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN)
145 continue;
146 break;
147 }
148 if (IS_ERR(err)) {
149 put_unused_fd(fd);
150 return PTR_ERR(err);
151 }
152
153 f = dentry_open(&path, O_RDONLY, current_cred());
154 path_put(&path);
155 if (IS_ERR(f)) {
156 put_unused_fd(fd);
157 fd = PTR_ERR(f);
158 } else
159 fd_install(fd, f);
160
161 return fd;
162}
163
164static long ns_ioctl(struct file *filp, unsigned int ioctl,
165 unsigned long arg)
166{
167 struct ns_common *ns = get_proc_ns(file_inode(filp));
168
169 switch (ioctl) {
170 case NS_GET_USERNS:
171 return open_related_ns(ns, ns_get_owner);
Andrey Vagina7306ed2016-09-06 00:47:15 -0700172 case NS_GET_PARENT:
173 if (!ns->ops->get_parent)
174 return -EINVAL;
175 return open_related_ns(ns, ns->ops->get_parent);
Andrey Vagin67867412016-09-06 00:47:14 -0700176 default:
177 return -ENOTTY;
178 }
179}
180
Al Viroe149ed22014-11-01 10:57:28 -0400181int ns_get_name(char *buf, size_t size, struct task_struct *task,
182 const struct proc_ns_operations *ns_ops)
183{
184 struct ns_common *ns;
185 int res = -ENOENT;
186 ns = ns_ops->get(task);
187 if (ns) {
188 res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum);
189 ns_ops->put(ns);
190 }
191 return res;
192}
193
194struct file *proc_ns_fget(int fd)
195{
196 struct file *file;
197
198 file = fget(fd);
199 if (!file)
200 return ERR_PTR(-EBADF);
201
202 if (file->f_op != &ns_file_operations)
203 goto out_invalid;
204
205 return file;
206
207out_invalid:
208 fput(file);
209 return ERR_PTR(-EINVAL);
210}
211
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500212static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
213{
214 struct inode *inode = d_inode(dentry);
215 const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
216
Joe Perches6798a8c2015-09-11 13:07:48 -0700217 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
218 return 0;
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500219}
220
Al Viroe149ed22014-11-01 10:57:28 -0400221static const struct super_operations nsfs_ops = {
222 .statfs = simple_statfs,
223 .evict_inode = nsfs_evict,
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500224 .show_path = nsfs_show_path,
Al Viroe149ed22014-11-01 10:57:28 -0400225};
226static struct dentry *nsfs_mount(struct file_system_type *fs_type,
227 int flags, const char *dev_name, void *data)
228{
229 return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
230 &ns_dentry_operations, NSFS_MAGIC);
231}
232static struct file_system_type nsfs = {
233 .name = "nsfs",
234 .mount = nsfs_mount,
235 .kill_sb = kill_anon_super,
236};
237
238void __init nsfs_init(void)
239{
240 nsfs_mnt = kern_mount(&nsfs);
241 if (IS_ERR(nsfs_mnt))
242 panic("can't set nsfs up\n");
243 nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;
244}