1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/mount.h>
3 #include <linux/pseudo_fs.h>
4 #include <linux/file.h>
5 #include <linux/fs.h>
6 #include <linux/proc_fs.h>
7 #include <linux/proc_ns.h>
8 #include <linux/magic.h>
9 #include <linux/ktime.h>
10 #include <linux/seq_file.h>
11 #include <linux/pid_namespace.h>
12 #include <linux/user_namespace.h>
13 #include <linux/nsfs.h>
14 #include <linux/uaccess.h>
15
16 #include "mount.h"
17 #include "internal.h"
18
19 static struct vfsmount *nsfs_mnt;
20
21 static long ns_ioctl(struct file *filp, unsigned int ioctl,
22 unsigned long arg);
23 static const struct file_operations ns_file_operations = {
24 .llseek = no_llseek,
25 .unlocked_ioctl = ns_ioctl,
26 .compat_ioctl = compat_ptr_ioctl,
27 };
28
29 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
30 {
31 struct inode *inode = d_inode(dentry);
32 struct ns_common *ns = inode->i_private;
33 const struct proc_ns_operations *ns_ops = ns->ops;
34
35 return dynamic_dname(buffer, buflen, "%s:[%lu]",
36 ns_ops->name, inode->i_ino);
37 }
38
39 const struct dentry_operations ns_dentry_operations = {
40 .d_delete = always_delete_dentry,
41 .d_dname = ns_dname,
42 .d_prune = stashed_dentry_prune,
43 };
44
45 static 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
52 int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
53 void *private_data)
54 {
55 struct ns_common *ns;
56
57 ns = ns_get_cb(private_data);
58 if (!ns)
59 return -ENOENT;
60
61 return path_from_stashed(&ns->stashed, nsfs_mnt, ns, path);
62 }
63
64 struct ns_get_path_task_args {
65 const struct proc_ns_operations *ns_ops;
66 struct task_struct *task;
67 };
68
69 static struct ns_common *ns_get_path_task(void *private_data)
70 {
71 struct ns_get_path_task_args *args = private_data;
72
73 return args->ns_ops->get(args->task);
74 }
75
76 int ns_get_path(struct path *path, struct task_struct *task,
77 const struct proc_ns_operations *ns_ops)
78 {
79 struct ns_get_path_task_args args = {
80 .ns_ops = ns_ops,
81 .task = task,
82 };
83
84 return ns_get_path_cb(path, ns_get_path_task, &args);
85 }
86
87 /**
88 * open_namespace - open a namespace
89 * @ns: the namespace to open
90 *
91 * This will consume a reference to @ns indendent of success or failure.
92 *
93 * Return: A file descriptor on success or a negative error code on failure.
94 */
95 int open_namespace(struct ns_common *ns)
96 {
97 struct path path __free(path_put) = {};
98 struct file *f;
99 int err;
100
101 /* call first to consume reference */
102 err = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path);
103 if (err < 0)
104 return err;
105
106 CLASS(get_unused_fd, fd)(O_CLOEXEC);
107 if (fd < 0)
108 return fd;
109
110 f = dentry_open(&path, O_RDONLY, current_cred());
111 if (IS_ERR(f))
112 return PTR_ERR(f);
113
114 fd_install(fd, f);
115 return take_fd(fd);
116 }
117
118 int open_related_ns(struct ns_common *ns,
119 struct ns_common *(*get_ns)(struct ns_common *ns))
120 {
121 struct ns_common *relative;
122
123 relative = get_ns(ns);
124 if (IS_ERR(relative))
125 return PTR_ERR(relative);
126
127 return open_namespace(relative);
128 }
129 EXPORT_SYMBOL_GPL(open_related_ns);
130
131 static long ns_ioctl(struct file *filp, unsigned int ioctl,
132 unsigned long arg)
133 {
134 struct user_namespace *user_ns;
135 struct pid_namespace *pid_ns;
136 struct task_struct *tsk;
137 struct ns_common *ns = get_proc_ns(file_inode(filp));
138 uid_t __user *argp;
139 uid_t uid;
140 int ret;
141
142 switch (ioctl) {
143 case NS_GET_USERNS:
144 return open_related_ns(ns, ns_get_owner);
145 case NS_GET_PARENT:
146 if (!ns->ops->get_parent)
147 return -EINVAL;
148 return open_related_ns(ns, ns->ops->get_parent);
149 case NS_GET_NSTYPE:
150 return ns->ops->type;
151 case NS_GET_OWNER_UID:
152 if (ns->ops->type != CLONE_NEWUSER)
153 return -EINVAL;
154 user_ns = container_of(ns, struct user_namespace, ns);
155 argp = (uid_t __user *) arg;
156 uid = from_kuid_munged(current_user_ns(), user_ns->owner);
157 return put_user(uid, argp);
158 case NS_GET_MNTNS_ID: {
159 struct mnt_namespace *mnt_ns;
160 __u64 __user *idp;
161 __u64 id;
162
163 if (ns->ops->type != CLONE_NEWNS)
164 return -EINVAL;
165
166 mnt_ns = container_of(ns, struct mnt_namespace, ns);
167 idp = (__u64 __user *)arg;
168 id = mnt_ns->seq;
169 return put_user(id, idp);
170 }
171 case NS_GET_PID_FROM_PIDNS:
172 fallthrough;
173 case NS_GET_TGID_FROM_PIDNS:
174 fallthrough;
175 case NS_GET_PID_IN_PIDNS:
176 fallthrough;
177 case NS_GET_TGID_IN_PIDNS: {
178 if (ns->ops->type != CLONE_NEWPID)
179 return -EINVAL;
180
181 ret = -ESRCH;
182 pid_ns = container_of(ns, struct pid_namespace, ns);
183
184 guard(rcu)();
185
186 if (ioctl == NS_GET_PID_IN_PIDNS ||
187 ioctl == NS_GET_TGID_IN_PIDNS)
188 tsk = find_task_by_vpid(arg);
189 else
190 tsk = find_task_by_pid_ns(arg, pid_ns);
191 if (!tsk)
192 break;
193
194 switch (ioctl) {
195 case NS_GET_PID_FROM_PIDNS:
196 ret = task_pid_vnr(tsk);
197 break;
198 case NS_GET_TGID_FROM_PIDNS:
199 ret = task_tgid_vnr(tsk);
200 break;
201 case NS_GET_PID_IN_PIDNS:
202 ret = task_pid_nr_ns(tsk, pid_ns);
203 break;
204 case NS_GET_TGID_IN_PIDNS:
205 ret = task_tgid_nr_ns(tsk, pid_ns);
206 break;
207 default:
208 ret = 0;
209 break;
210 }
211
212 if (!ret)
213 ret = -ESRCH;
214 break;
215 }
216 default:
217 ret = -ENOTTY;
218 }
219
220 return ret;
221 }
222
223 int ns_get_name(char *buf, size_t size, struct task_struct *task,
224 const struct proc_ns_operations *ns_ops)
225 {
226 struct ns_common *ns;
227 int res = -ENOENT;
228 const char *name;
229 ns = ns_ops->get(task);
230 if (ns) {
231 name = ns_ops->real_ns_name ? : ns_ops->name;
232 res = snprintf(buf, size, "%s:[%u]", name, ns->inum);
233 ns_ops->put(ns);
234 }
235 return res;
236 }
237
238 bool proc_ns_file(const struct file *file)
239 {
240 return file->f_op == &ns_file_operations;
241 }
242
243 /**
244 * ns_match() - Returns true if current namespace matches dev/ino provided.
245 * @ns: current namespace
246 * @dev: dev_t from nsfs that will be matched against current nsfs
247 * @ino: ino_t from nsfs that will be matched against current nsfs
248 *
249 * Return: true if dev and ino matches the current nsfs.
250 */
251 bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
252 {
253 return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
254 }
255
256
257 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
258 {
259 struct inode *inode = d_inode(dentry);
260 const struct ns_common *ns = inode->i_private;
261 const struct proc_ns_operations *ns_ops = ns->ops;
262
263 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
264 return 0;
265 }
266
267 static const struct super_operations nsfs_ops = {
268 .statfs = simple_statfs,
269 .evict_inode = nsfs_evict,
270 .show_path = nsfs_show_path,
271 };
272
273 static int nsfs_init_inode(struct inode *inode, void *data)
274 {
275 struct ns_common *ns = data;
276
277 inode->i_private = data;
278 inode->i_mode |= S_IRUGO;
279 inode->i_fop = &ns_file_operations;
280 inode->i_ino = ns->inum;
281 return 0;
282 }
283
284 static void nsfs_put_data(void *data)
285 {
286 struct ns_common *ns = data;
287 ns->ops->put(ns);
288 }
289
290 static const struct stashed_operations nsfs_stashed_ops = {
291 .init_inode = nsfs_init_inode,
292 .put_data = nsfs_put_data,
293 };
294
295 static int nsfs_init_fs_context(struct fs_context *fc)
296 {
297 struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
298 if (!ctx)
299 return -ENOMEM;
300 ctx->ops = &nsfs_ops;
301 ctx->dops = &ns_dentry_operations;
302 fc->s_fs_info = (void *)&nsfs_stashed_ops;
303 return 0;
304 }
305
306 static struct file_system_type nsfs = {
307 .name = "nsfs",
308 .init_fs_context = nsfs_init_fs_context,
309 .kill_sb = kill_anon_super,
310 };
311
312 void __init nsfs_init(void)
313 {
314 nsfs_mnt = kern_mount(&nsfs);
315 if (IS_ERR(nsfs_mnt))
316 panic("can't set nsfs up\n");
317 nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
318 }
319
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