xref: /openbmc/linux/security/keys/proc.c (revision dcf49dbc) 
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/init.h>
13 #include <linux/sched.h>
14 #include <linux/fs.h>
15 #include <linux/proc_fs.h>
16 #include <linux/seq_file.h>
17 #include <asm/errno.h>
18 #include "internal.h"
19 
20 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
21 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
22 static void proc_keys_stop(struct seq_file *p, void *v);
23 static int proc_keys_show(struct seq_file *m, void *v);
24 
25 static const struct seq_operations proc_keys_ops = {
26 	.start	= proc_keys_start,
27 	.next	= proc_keys_next,
28 	.stop	= proc_keys_stop,
29 	.show	= proc_keys_show,
30 };
31 
32 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
33 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
34 static void proc_key_users_stop(struct seq_file *p, void *v);
35 static int proc_key_users_show(struct seq_file *m, void *v);
36 
37 static const struct seq_operations proc_key_users_ops = {
38 	.start	= proc_key_users_start,
39 	.next	= proc_key_users_next,
40 	.stop	= proc_key_users_stop,
41 	.show	= proc_key_users_show,
42 };
43 
44 /*
45  * Declare the /proc files.
46  */
47 static int __init key_proc_init(void)
48 {
49 	struct proc_dir_entry *p;
50 
51 	p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
52 	if (!p)
53 		panic("Cannot create /proc/keys\n");
54 
55 	p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
56 	if (!p)
57 		panic("Cannot create /proc/key-users\n");
58 
59 	return 0;
60 }
61 
62 __initcall(key_proc_init);
63 
64 /*
65  * Implement "/proc/keys" to provide a list of the keys on the system that
66  * grant View permission to the caller.
67  */
68 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
69 {
70 	struct user_namespace *user_ns = seq_user_ns(p);
71 
72 	n = rb_next(n);
73 	while (n) {
74 		struct key *key = rb_entry(n, struct key, serial_node);
75 		if (kuid_has_mapping(user_ns, key->user->uid))
76 			break;
77 		n = rb_next(n);
78 	}
79 	return n;
80 }
81 
82 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
83 {
84 	struct user_namespace *user_ns = seq_user_ns(p);
85 	struct rb_node *n = key_serial_tree.rb_node;
86 	struct key *minkey = NULL;
87 
88 	while (n) {
89 		struct key *key = rb_entry(n, struct key, serial_node);
90 		if (id < key->serial) {
91 			if (!minkey || minkey->serial > key->serial)
92 				minkey = key;
93 			n = n->rb_left;
94 		} else if (id > key->serial) {
95 			n = n->rb_right;
96 		} else {
97 			minkey = key;
98 			break;
99 		}
100 		key = NULL;
101 	}
102 
103 	if (!minkey)
104 		return NULL;
105 
106 	for (;;) {
107 		if (kuid_has_mapping(user_ns, minkey->user->uid))
108 			return minkey;
109 		n = rb_next(&minkey->serial_node);
110 		if (!n)
111 			return NULL;
112 		minkey = rb_entry(n, struct key, serial_node);
113 	}
114 }
115 
116 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
117 	__acquires(key_serial_lock)
118 {
119 	key_serial_t pos = *_pos;
120 	struct key *key;
121 
122 	spin_lock(&key_serial_lock);
123 
124 	if (*_pos > INT_MAX)
125 		return NULL;
126 	key = find_ge_key(p, pos);
127 	if (!key)
128 		return NULL;
129 	*_pos = key->serial;
130 	return &key->serial_node;
131 }
132 
133 static inline key_serial_t key_node_serial(struct rb_node *n)
134 {
135 	struct key *key = rb_entry(n, struct key, serial_node);
136 	return key->serial;
137 }
138 
139 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
140 {
141 	struct rb_node *n;
142 
143 	n = key_serial_next(p, v);
144 	if (n)
145 		*_pos = key_node_serial(n);
146 	return n;
147 }
148 
149 static void proc_keys_stop(struct seq_file *p, void *v)
150 	__releases(key_serial_lock)
151 {
152 	spin_unlock(&key_serial_lock);
153 }
154 
155 static int proc_keys_show(struct seq_file *m, void *v)
156 {
157 	struct rb_node *_p = v;
158 	struct key *key = rb_entry(_p, struct key, serial_node);
159 	unsigned long flags;
160 	key_ref_t key_ref, skey_ref;
161 	time64_t now, expiry;
162 	char xbuf[16];
163 	short state;
164 	u64 timo;
165 	int rc;
166 
167 	struct keyring_search_context ctx = {
168 		.index_key		= key->index_key,
169 		.cred			= m->file->f_cred,
170 		.match_data.cmp		= lookup_user_key_possessed,
171 		.match_data.raw_data	= key,
172 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
173 		.flags			= (KEYRING_SEARCH_NO_STATE_CHECK |
174 					   KEYRING_SEARCH_RECURSE),
175 	};
176 
177 	key_ref = make_key_ref(key, 0);
178 
179 	/* determine if the key is possessed by this process (a test we can
180 	 * skip if the key does not indicate the possessor can view it
181 	 */
182 	if (key->perm & KEY_POS_VIEW) {
183 		rcu_read_lock();
184 		skey_ref = search_cred_keyrings_rcu(&ctx);
185 		rcu_read_unlock();
186 		if (!IS_ERR(skey_ref)) {
187 			key_ref_put(skey_ref);
188 			key_ref = make_key_ref(key, 1);
189 		}
190 	}
191 
192 	/* check whether the current task is allowed to view the key */
193 	rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
194 	if (rc < 0)
195 		return 0;
196 
197 	now = ktime_get_real_seconds();
198 
199 	rcu_read_lock();
200 
201 	/* come up with a suitable timeout value */
202 	expiry = READ_ONCE(key->expiry);
203 	if (expiry == 0) {
204 		memcpy(xbuf, "perm", 5);
205 	} else if (now >= expiry) {
206 		memcpy(xbuf, "expd", 5);
207 	} else {
208 		timo = expiry - now;
209 
210 		if (timo < 60)
211 			sprintf(xbuf, "%llus", timo);
212 		else if (timo < 60*60)
213 			sprintf(xbuf, "%llum", div_u64(timo, 60));
214 		else if (timo < 60*60*24)
215 			sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
216 		else if (timo < 60*60*24*7)
217 			sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
218 		else
219 			sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
220 	}
221 
222 	state = key_read_state(key);
223 
224 #define showflag(FLAGS, LETTER, FLAG) \
225 	((FLAGS & (1 << FLAG)) ? LETTER : '-')
226 
227 	flags = READ_ONCE(key->flags);
228 	seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
229 		   key->serial,
230 		   state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
231 		   showflag(flags, 'R', KEY_FLAG_REVOKED),
232 		   showflag(flags, 'D', KEY_FLAG_DEAD),
233 		   showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
234 		   showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
235 		   state < 0 ? 'N' : '-',
236 		   showflag(flags, 'i', KEY_FLAG_INVALIDATED),
237 		   refcount_read(&key->usage),
238 		   xbuf,
239 		   key->perm,
240 		   from_kuid_munged(seq_user_ns(m), key->uid),
241 		   from_kgid_munged(seq_user_ns(m), key->gid),
242 		   key->type->name);
243 
244 #undef showflag
245 
246 	if (key->type->describe)
247 		key->type->describe(key, m);
248 	seq_putc(m, '\n');
249 
250 	rcu_read_unlock();
251 	return 0;
252 }
253 
254 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
255 {
256 	while (n) {
257 		struct key_user *user = rb_entry(n, struct key_user, node);
258 		if (kuid_has_mapping(user_ns, user->uid))
259 			break;
260 		n = rb_next(n);
261 	}
262 	return n;
263 }
264 
265 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
266 {
267 	return __key_user_next(user_ns, rb_next(n));
268 }
269 
270 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
271 {
272 	struct rb_node *n = rb_first(r);
273 	return __key_user_next(user_ns, n);
274 }
275 
276 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
277 	__acquires(key_user_lock)
278 {
279 	struct rb_node *_p;
280 	loff_t pos = *_pos;
281 
282 	spin_lock(&key_user_lock);
283 
284 	_p = key_user_first(seq_user_ns(p), &key_user_tree);
285 	while (pos > 0 && _p) {
286 		pos--;
287 		_p = key_user_next(seq_user_ns(p), _p);
288 	}
289 
290 	return _p;
291 }
292 
293 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
294 {
295 	(*_pos)++;
296 	return key_user_next(seq_user_ns(p), (struct rb_node *)v);
297 }
298 
299 static void proc_key_users_stop(struct seq_file *p, void *v)
300 	__releases(key_user_lock)
301 {
302 	spin_unlock(&key_user_lock);
303 }
304 
305 static int proc_key_users_show(struct seq_file *m, void *v)
306 {
307 	struct rb_node *_p = v;
308 	struct key_user *user = rb_entry(_p, struct key_user, node);
309 	unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
310 		key_quota_root_maxkeys : key_quota_maxkeys;
311 	unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
312 		key_quota_root_maxbytes : key_quota_maxbytes;
313 
314 	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
315 		   from_kuid_munged(seq_user_ns(m), user->uid),
316 		   refcount_read(&user->usage),
317 		   atomic_read(&user->nkeys),
318 		   atomic_read(&user->nikeys),
319 		   user->qnkeys,
320 		   maxkeys,
321 		   user->qnbytes,
322 		   maxbytes);
323 
324 	return 0;
325 }
326