xref: /openbmc/linux/security/keys/proc.c (revision 3b64b188) 
1 /* procfs files for key database enumeration
2  *
3  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells (dhowells@redhat.com)
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  */
11 
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/fs.h>
16 #include <linux/proc_fs.h>
17 #include <linux/seq_file.h>
18 #include <asm/errno.h>
19 #include "internal.h"
20 
21 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
22 static int proc_keys_open(struct inode *inode, struct file *file);
23 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
24 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
25 static void proc_keys_stop(struct seq_file *p, void *v);
26 static int proc_keys_show(struct seq_file *m, void *v);
27 
28 static const struct seq_operations proc_keys_ops = {
29 	.start	= proc_keys_start,
30 	.next	= proc_keys_next,
31 	.stop	= proc_keys_stop,
32 	.show	= proc_keys_show,
33 };
34 
35 static const struct file_operations proc_keys_fops = {
36 	.open		= proc_keys_open,
37 	.read		= seq_read,
38 	.llseek		= seq_lseek,
39 	.release	= seq_release,
40 };
41 #endif
42 
43 static int proc_key_users_open(struct inode *inode, struct file *file);
44 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
45 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
46 static void proc_key_users_stop(struct seq_file *p, void *v);
47 static int proc_key_users_show(struct seq_file *m, void *v);
48 
49 static const struct seq_operations proc_key_users_ops = {
50 	.start	= proc_key_users_start,
51 	.next	= proc_key_users_next,
52 	.stop	= proc_key_users_stop,
53 	.show	= proc_key_users_show,
54 };
55 
56 static const struct file_operations proc_key_users_fops = {
57 	.open		= proc_key_users_open,
58 	.read		= seq_read,
59 	.llseek		= seq_lseek,
60 	.release	= seq_release,
61 };
62 
63 /*
64  * Declare the /proc files.
65  */
66 static int __init key_proc_init(void)
67 {
68 	struct proc_dir_entry *p;
69 
70 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
71 	p = proc_create("keys", 0, NULL, &proc_keys_fops);
72 	if (!p)
73 		panic("Cannot create /proc/keys\n");
74 #endif
75 
76 	p = proc_create("key-users", 0, NULL, &proc_key_users_fops);
77 	if (!p)
78 		panic("Cannot create /proc/key-users\n");
79 
80 	return 0;
81 }
82 
83 __initcall(key_proc_init);
84 
85 /*
86  * Implement "/proc/keys" to provide a list of the keys on the system that
87  * grant View permission to the caller.
88  */
89 #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
90 
91 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
92 {
93 	struct user_namespace *user_ns = seq_user_ns(p);
94 
95 	n = rb_next(n);
96 	while (n) {
97 		struct key *key = rb_entry(n, struct key, serial_node);
98 		if (kuid_has_mapping(user_ns, key->user->uid))
99 			break;
100 		n = rb_next(n);
101 	}
102 	return n;
103 }
104 
105 static int proc_keys_open(struct inode *inode, struct file *file)
106 {
107 	return seq_open(file, &proc_keys_ops);
108 }
109 
110 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
111 {
112 	struct user_namespace *user_ns = seq_user_ns(p);
113 	struct rb_node *n = key_serial_tree.rb_node;
114 	struct key *minkey = NULL;
115 
116 	while (n) {
117 		struct key *key = rb_entry(n, struct key, serial_node);
118 		if (id < key->serial) {
119 			if (!minkey || minkey->serial > key->serial)
120 				minkey = key;
121 			n = n->rb_left;
122 		} else if (id > key->serial) {
123 			n = n->rb_right;
124 		} else {
125 			minkey = key;
126 			break;
127 		}
128 		key = NULL;
129 	}
130 
131 	if (!minkey)
132 		return NULL;
133 
134 	for (;;) {
135 		if (kuid_has_mapping(user_ns, minkey->user->uid))
136 			return minkey;
137 		n = rb_next(&minkey->serial_node);
138 		if (!n)
139 			return NULL;
140 		minkey = rb_entry(n, struct key, serial_node);
141 	}
142 }
143 
144 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
145 	__acquires(key_serial_lock)
146 {
147 	key_serial_t pos = *_pos;
148 	struct key *key;
149 
150 	spin_lock(&key_serial_lock);
151 
152 	if (*_pos > INT_MAX)
153 		return NULL;
154 	key = find_ge_key(p, pos);
155 	if (!key)
156 		return NULL;
157 	*_pos = key->serial;
158 	return &key->serial_node;
159 }
160 
161 static inline key_serial_t key_node_serial(struct rb_node *n)
162 {
163 	struct key *key = rb_entry(n, struct key, serial_node);
164 	return key->serial;
165 }
166 
167 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
168 {
169 	struct rb_node *n;
170 
171 	n = key_serial_next(p, v);
172 	if (n)
173 		*_pos = key_node_serial(n);
174 	return n;
175 }
176 
177 static void proc_keys_stop(struct seq_file *p, void *v)
178 	__releases(key_serial_lock)
179 {
180 	spin_unlock(&key_serial_lock);
181 }
182 
183 static int proc_keys_show(struct seq_file *m, void *v)
184 {
185 	const struct cred *cred = current_cred();
186 	struct rb_node *_p = v;
187 	struct key *key = rb_entry(_p, struct key, serial_node);
188 	struct timespec now;
189 	unsigned long timo;
190 	key_ref_t key_ref, skey_ref;
191 	char xbuf[12];
192 	int rc;
193 
194 	key_ref = make_key_ref(key, 0);
195 
196 	/* determine if the key is possessed by this process (a test we can
197 	 * skip if the key does not indicate the possessor can view it
198 	 */
199 	if (key->perm & KEY_POS_VIEW) {
200 		skey_ref = search_my_process_keyrings(key->type, key,
201 						      lookup_user_key_possessed,
202 						      true, cred);
203 		if (!IS_ERR(skey_ref)) {
204 			key_ref_put(skey_ref);
205 			key_ref = make_key_ref(key, 1);
206 		}
207 	}
208 
209 	/* check whether the current task is allowed to view the key (assuming
210 	 * non-possession)
211 	 * - the caller holds a spinlock, and thus the RCU read lock, making our
212 	 *   access to __current_cred() safe
213 	 */
214 	rc = key_task_permission(key_ref, cred, KEY_VIEW);
215 	if (rc < 0)
216 		return 0;
217 
218 	now = current_kernel_time();
219 
220 	rcu_read_lock();
221 
222 	/* come up with a suitable timeout value */
223 	if (key->expiry == 0) {
224 		memcpy(xbuf, "perm", 5);
225 	} else if (now.tv_sec >= key->expiry) {
226 		memcpy(xbuf, "expd", 5);
227 	} else {
228 		timo = key->expiry - now.tv_sec;
229 
230 		if (timo < 60)
231 			sprintf(xbuf, "%lus", timo);
232 		else if (timo < 60*60)
233 			sprintf(xbuf, "%lum", timo / 60);
234 		else if (timo < 60*60*24)
235 			sprintf(xbuf, "%luh", timo / (60*60));
236 		else if (timo < 60*60*24*7)
237 			sprintf(xbuf, "%lud", timo / (60*60*24));
238 		else
239 			sprintf(xbuf, "%luw", timo / (60*60*24*7));
240 	}
241 
242 #define showflag(KEY, LETTER, FLAG) \
243 	(test_bit(FLAG,	&(KEY)->flags) ? LETTER : '-')
244 
245 	seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
246 		   key->serial,
247 		   showflag(key, 'I', KEY_FLAG_INSTANTIATED),
248 		   showflag(key, 'R', KEY_FLAG_REVOKED),
249 		   showflag(key, 'D', KEY_FLAG_DEAD),
250 		   showflag(key, 'Q', KEY_FLAG_IN_QUOTA),
251 		   showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT),
252 		   showflag(key, 'N', KEY_FLAG_NEGATIVE),
253 		   showflag(key, 'i', KEY_FLAG_INVALIDATED),
254 		   atomic_read(&key->usage),
255 		   xbuf,
256 		   key->perm,
257 		   from_kuid_munged(seq_user_ns(m), key->uid),
258 		   from_kgid_munged(seq_user_ns(m), key->gid),
259 		   key->type->name);
260 
261 #undef showflag
262 
263 	if (key->type->describe)
264 		key->type->describe(key, m);
265 	seq_putc(m, '\n');
266 
267 	rcu_read_unlock();
268 	return 0;
269 }
270 
271 #endif /* CONFIG_KEYS_DEBUG_PROC_KEYS */
272 
273 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
274 {
275 	while (n) {
276 		struct key_user *user = rb_entry(n, struct key_user, node);
277 		if (kuid_has_mapping(user_ns, user->uid))
278 			break;
279 		n = rb_next(n);
280 	}
281 	return n;
282 }
283 
284 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
285 {
286 	return __key_user_next(user_ns, rb_next(n));
287 }
288 
289 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
290 {
291 	struct rb_node *n = rb_first(r);
292 	return __key_user_next(user_ns, n);
293 }
294 
295 /*
296  * Implement "/proc/key-users" to provides a list of the key users and their
297  * quotas.
298  */
299 static int proc_key_users_open(struct inode *inode, struct file *file)
300 {
301 	return seq_open(file, &proc_key_users_ops);
302 }
303 
304 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
305 	__acquires(key_user_lock)
306 {
307 	struct rb_node *_p;
308 	loff_t pos = *_pos;
309 
310 	spin_lock(&key_user_lock);
311 
312 	_p = key_user_first(seq_user_ns(p), &key_user_tree);
313 	while (pos > 0 && _p) {
314 		pos--;
315 		_p = key_user_next(seq_user_ns(p), _p);
316 	}
317 
318 	return _p;
319 }
320 
321 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
322 {
323 	(*_pos)++;
324 	return key_user_next(seq_user_ns(p), (struct rb_node *)v);
325 }
326 
327 static void proc_key_users_stop(struct seq_file *p, void *v)
328 	__releases(key_user_lock)
329 {
330 	spin_unlock(&key_user_lock);
331 }
332 
333 static int proc_key_users_show(struct seq_file *m, void *v)
334 {
335 	struct rb_node *_p = v;
336 	struct key_user *user = rb_entry(_p, struct key_user, node);
337 	unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
338 		key_quota_root_maxkeys : key_quota_maxkeys;
339 	unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
340 		key_quota_root_maxbytes : key_quota_maxbytes;
341 
342 	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
343 		   from_kuid_munged(seq_user_ns(m), user->uid),
344 		   atomic_read(&user->usage),
345 		   atomic_read(&user->nkeys),
346 		   atomic_read(&user->nikeys),
347 		   user->qnkeys,
348 		   maxkeys,
349 		   user->qnbytes,
350 		   maxbytes);
351 
352 	return 0;
353 }
354