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Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
e149ed2b AV |
2 | #include <linux/mount.h> |
3 | #include <linux/file.h> | |
4 | #include <linux/fs.h> | |
5 | #include <linux/proc_ns.h> | |
6 | #include <linux/magic.h> | |
7 | #include <linux/ktime.h> | |
75509fd8 | 8 | #include <linux/seq_file.h> |
6786741d AV |
9 | #include <linux/user_namespace.h> |
10 | #include <linux/nsfs.h> | |
d95fa3c7 | 11 | #include <linux/uaccess.h> |
e149ed2b AV |
12 | |
13 | static struct vfsmount *nsfs_mnt; | |
14 | ||
6786741d AV |
15 | static long ns_ioctl(struct file *filp, unsigned int ioctl, |
16 | unsigned long arg); | |
e149ed2b AV |
17 | static const struct file_operations ns_file_operations = { |
18 | .llseek = no_llseek, | |
6786741d | 19 | .unlocked_ioctl = ns_ioctl, |
e149ed2b AV |
20 | }; |
21 | ||
22 | static char *ns_dname(struct dentry *dentry, char *buffer, int buflen) | |
23 | { | |
75c3cfa8 | 24 | struct inode *inode = d_inode(dentry); |
e149ed2b AV |
25 | const struct proc_ns_operations *ns_ops = dentry->d_fsdata; |
26 | ||
27 | return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]", | |
28 | ns_ops->name, inode->i_ino); | |
29 | } | |
30 | ||
31 | static void ns_prune_dentry(struct dentry *dentry) | |
32 | { | |
75c3cfa8 | 33 | struct inode *inode = d_inode(dentry); |
e149ed2b AV |
34 | if (inode) { |
35 | struct ns_common *ns = inode->i_private; | |
36 | atomic_long_set(&ns->stashed, 0); | |
37 | } | |
38 | } | |
39 | ||
40 | const struct dentry_operations ns_dentry_operations = | |
41 | { | |
42 | .d_prune = ns_prune_dentry, | |
43 | .d_delete = always_delete_dentry, | |
44 | .d_dname = ns_dname, | |
45 | }; | |
46 | ||
47 | static void nsfs_evict(struct inode *inode) | |
48 | { | |
49 | struct ns_common *ns = inode->i_private; | |
50 | clear_inode(inode); | |
51 | ns->ops->put(ns); | |
52 | } | |
53 | ||
6786741d | 54 | static void *__ns_get_path(struct path *path, struct ns_common *ns) |
e149ed2b | 55 | { |
213b067c | 56 | struct vfsmount *mnt = nsfs_mnt; |
e149ed2b AV |
57 | struct dentry *dentry; |
58 | struct inode *inode; | |
e149ed2b AV |
59 | unsigned long d; |
60 | ||
e149ed2b AV |
61 | rcu_read_lock(); |
62 | d = atomic_long_read(&ns->stashed); | |
63 | if (!d) | |
64 | goto slow; | |
65 | dentry = (struct dentry *)d; | |
66 | if (!lockref_get_not_dead(&dentry->d_lockref)) | |
67 | goto slow; | |
68 | rcu_read_unlock(); | |
6786741d | 69 | ns->ops->put(ns); |
e149ed2b | 70 | got_it: |
213b067c | 71 | path->mnt = mntget(mnt); |
e149ed2b AV |
72 | path->dentry = dentry; |
73 | return NULL; | |
74 | slow: | |
75 | rcu_read_unlock(); | |
76 | inode = new_inode_pseudo(mnt->mnt_sb); | |
77 | if (!inode) { | |
6786741d | 78 | ns->ops->put(ns); |
e149ed2b AV |
79 | return ERR_PTR(-ENOMEM); |
80 | } | |
81 | inode->i_ino = ns->inum; | |
078cd827 | 82 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); |
e149ed2b AV |
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; | |
87 | ||
5467a68c | 88 | dentry = d_alloc_anon(mnt->mnt_sb); |
e149ed2b AV |
89 | if (!dentry) { |
90 | iput(inode); | |
e149ed2b AV |
91 | return ERR_PTR(-ENOMEM); |
92 | } | |
93 | d_instantiate(dentry, inode); | |
6786741d | 94 | dentry->d_fsdata = (void *)ns->ops; |
e149ed2b AV |
95 | 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(); | |
6786741d | 100 | return ERR_PTR(-EAGAIN); |
e149ed2b AV |
101 | } |
102 | goto got_it; | |
103 | } | |
104 | ||
cdab6ba8 JK |
105 | void *ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb, |
106 | void *private_data) | |
6786741d | 107 | { |
6786741d AV |
108 | void *ret; |
109 | ||
357ab5b5 AV |
110 | do { |
111 | struct ns_common *ns = ns_get_cb(private_data); | |
112 | if (!ns) | |
113 | return ERR_PTR(-ENOENT); | |
114 | ||
115 | ret = __ns_get_path(path, ns); | |
116 | } while (ret == ERR_PTR(-EAGAIN)); | |
6786741d | 117 | |
6786741d AV |
118 | return ret; |
119 | } | |
120 | ||
cdab6ba8 JK |
121 | struct ns_get_path_task_args { |
122 | const struct proc_ns_operations *ns_ops; | |
123 | struct task_struct *task; | |
124 | }; | |
125 | ||
126 | static struct ns_common *ns_get_path_task(void *private_data) | |
127 | { | |
128 | struct ns_get_path_task_args *args = private_data; | |
129 | ||
130 | return args->ns_ops->get(args->task); | |
131 | } | |
132 | ||
133 | void *ns_get_path(struct path *path, struct task_struct *task, | |
134 | const struct proc_ns_operations *ns_ops) | |
135 | { | |
136 | struct ns_get_path_task_args args = { | |
137 | .ns_ops = ns_ops, | |
138 | .task = task, | |
139 | }; | |
140 | ||
141 | return ns_get_path_cb(path, ns_get_path_task, &args); | |
142 | } | |
143 | ||
c62cce2c | 144 | int open_related_ns(struct ns_common *ns, |
6786741d AV |
145 | struct ns_common *(*get_ns)(struct ns_common *ns)) |
146 | { | |
147 | struct path path = {}; | |
148 | struct file *f; | |
149 | void *err; | |
150 | int fd; | |
151 | ||
152 | fd = get_unused_fd_flags(O_CLOEXEC); | |
153 | if (fd < 0) | |
154 | return fd; | |
155 | ||
357ab5b5 | 156 | do { |
6786741d AV |
157 | struct ns_common *relative; |
158 | ||
159 | relative = get_ns(ns); | |
160 | if (IS_ERR(relative)) { | |
161 | put_unused_fd(fd); | |
162 | return PTR_ERR(relative); | |
163 | } | |
164 | ||
165 | err = __ns_get_path(&path, relative); | |
357ab5b5 AV |
166 | } while (err == ERR_PTR(-EAGAIN)); |
167 | ||
6786741d AV |
168 | if (IS_ERR(err)) { |
169 | put_unused_fd(fd); | |
170 | return PTR_ERR(err); | |
171 | } | |
172 | ||
173 | f = dentry_open(&path, O_RDONLY, current_cred()); | |
174 | path_put(&path); | |
175 | if (IS_ERR(f)) { | |
176 | put_unused_fd(fd); | |
177 | fd = PTR_ERR(f); | |
178 | } else | |
179 | fd_install(fd, f); | |
180 | ||
181 | return fd; | |
182 | } | |
24dce080 | 183 | EXPORT_SYMBOL_GPL(open_related_ns); |
6786741d AV |
184 | |
185 | static long ns_ioctl(struct file *filp, unsigned int ioctl, | |
186 | unsigned long arg) | |
187 | { | |
d95fa3c7 | 188 | struct user_namespace *user_ns; |
6786741d | 189 | struct ns_common *ns = get_proc_ns(file_inode(filp)); |
d95fa3c7 MK |
190 | uid_t __user *argp; |
191 | uid_t uid; | |
6786741d AV |
192 | |
193 | switch (ioctl) { | |
194 | case NS_GET_USERNS: | |
195 | return open_related_ns(ns, ns_get_owner); | |
a7306ed8 AV |
196 | case NS_GET_PARENT: |
197 | if (!ns->ops->get_parent) | |
198 | return -EINVAL; | |
199 | return open_related_ns(ns, ns->ops->get_parent); | |
e5ff5ce6 MK |
200 | case NS_GET_NSTYPE: |
201 | return ns->ops->type; | |
d95fa3c7 MK |
202 | case NS_GET_OWNER_UID: |
203 | if (ns->ops->type != CLONE_NEWUSER) | |
204 | return -EINVAL; | |
205 | user_ns = container_of(ns, struct user_namespace, ns); | |
206 | argp = (uid_t __user *) arg; | |
207 | uid = from_kuid_munged(current_user_ns(), user_ns->owner); | |
208 | return put_user(uid, argp); | |
6786741d AV |
209 | default: |
210 | return -ENOTTY; | |
211 | } | |
212 | } | |
213 | ||
e149ed2b AV |
214 | int ns_get_name(char *buf, size_t size, struct task_struct *task, |
215 | const struct proc_ns_operations *ns_ops) | |
216 | { | |
217 | struct ns_common *ns; | |
218 | int res = -ENOENT; | |
25b14e92 | 219 | const char *name; |
e149ed2b AV |
220 | ns = ns_ops->get(task); |
221 | if (ns) { | |
25b14e92 KT |
222 | name = ns_ops->real_ns_name ? : ns_ops->name; |
223 | res = snprintf(buf, size, "%s:[%u]", name, ns->inum); | |
e149ed2b AV |
224 | ns_ops->put(ns); |
225 | } | |
226 | return res; | |
227 | } | |
228 | ||
229 | struct file *proc_ns_fget(int fd) | |
230 | { | |
231 | struct file *file; | |
232 | ||
233 | file = fget(fd); | |
234 | if (!file) | |
235 | return ERR_PTR(-EBADF); | |
236 | ||
237 | if (file->f_op != &ns_file_operations) | |
238 | goto out_invalid; | |
239 | ||
240 | return file; | |
241 | ||
242 | out_invalid: | |
243 | fput(file); | |
244 | return ERR_PTR(-EINVAL); | |
245 | } | |
246 | ||
75509fd8 EB |
247 | static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry) |
248 | { | |
249 | struct inode *inode = d_inode(dentry); | |
250 | const struct proc_ns_operations *ns_ops = dentry->d_fsdata; | |
251 | ||
6798a8ca JP |
252 | seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino); |
253 | return 0; | |
75509fd8 EB |
254 | } |
255 | ||
e149ed2b AV |
256 | static const struct super_operations nsfs_ops = { |
257 | .statfs = simple_statfs, | |
258 | .evict_inode = nsfs_evict, | |
75509fd8 | 259 | .show_path = nsfs_show_path, |
e149ed2b AV |
260 | }; |
261 | static struct dentry *nsfs_mount(struct file_system_type *fs_type, | |
262 | int flags, const char *dev_name, void *data) | |
263 | { | |
264 | return mount_pseudo(fs_type, "nsfs:", &nsfs_ops, | |
265 | &ns_dentry_operations, NSFS_MAGIC); | |
266 | } | |
267 | static struct file_system_type nsfs = { | |
268 | .name = "nsfs", | |
269 | .mount = nsfs_mount, | |
270 | .kill_sb = kill_anon_super, | |
271 | }; | |
272 | ||
273 | void __init nsfs_init(void) | |
274 | { | |
275 | nsfs_mnt = kern_mount(&nsfs); | |
276 | if (IS_ERR(nsfs_mnt)) | |
277 | panic("can't set nsfs up\n"); | |
1751e8a6 | 278 | nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER; |
e149ed2b | 279 | } |