xref: /openbmc/linux/security/keys/proc.c (revision 965f22bc) 
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 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
22 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
23 static void proc_keys_stop(struct seq_file *p, void *v);
24 static int proc_keys_show(struct seq_file *m, void *v);
25 
26 static const struct seq_operations proc_keys_ops = {
27 	.start	= proc_keys_start,
28 	.next	= proc_keys_next,
29 	.stop	= proc_keys_stop,
30 	.show	= proc_keys_show,
31 };
32 
33 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
34 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
35 static void proc_key_users_stop(struct seq_file *p, void *v);
36 static int proc_key_users_show(struct seq_file *m, void *v);
37 
38 static const struct seq_operations proc_key_users_ops = {
39 	.start	= proc_key_users_start,
40 	.next	= proc_key_users_next,
41 	.stop	= proc_key_users_stop,
42 	.show	= proc_key_users_show,
43 };
44 
45 /*
46  * Declare the /proc files.
47  */
48 static int __init key_proc_init(void)
49 {
50 	struct proc_dir_entry *p;
51 
52 	p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
53 	if (!p)
54 		panic("Cannot create /proc/keys\n");
55 
56 	p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
57 	if (!p)
58 		panic("Cannot create /proc/key-users\n");
59 
60 	return 0;
61 }
62 
63 __initcall(key_proc_init);
64 
65 /*
66  * Implement "/proc/keys" to provide a list of the keys on the system that
67  * grant View permission to the caller.
68  */
69 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
70 {
71 	struct user_namespace *user_ns = seq_user_ns(p);
72 
73 	n = rb_next(n);
74 	while (n) {
75 		struct key *key = rb_entry(n, struct key, serial_node);
76 		if (kuid_has_mapping(user_ns, key->user->uid))
77 			break;
78 		n = rb_next(n);
79 	}
80 	return n;
81 }
82 
83 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
84 {
85 	struct user_namespace *user_ns = seq_user_ns(p);
86 	struct rb_node *n = key_serial_tree.rb_node;
87 	struct key *minkey = NULL;
88 
89 	while (n) {
90 		struct key *key = rb_entry(n, struct key, serial_node);
91 		if (id < key->serial) {
92 			if (!minkey || minkey->serial > key->serial)
93 				minkey = key;
94 			n = n->rb_left;
95 		} else if (id > key->serial) {
96 			n = n->rb_right;
97 		} else {
98 			minkey = key;
99 			break;
100 		}
101 		key = NULL;
102 	}
103 
104 	if (!minkey)
105 		return NULL;
106 
107 	for (;;) {
108 		if (kuid_has_mapping(user_ns, minkey->user->uid))
109 			return minkey;
110 		n = rb_next(&minkey->serial_node);
111 		if (!n)
112 			return NULL;
113 		minkey = rb_entry(n, struct key, serial_node);
114 	}
115 }
116 
117 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
118 	__acquires(key_serial_lock)
119 {
120 	key_serial_t pos = *_pos;
121 	struct key *key;
122 
123 	spin_lock(&key_serial_lock);
124 
125 	if (*_pos > INT_MAX)
126 		return NULL;
127 	key = find_ge_key(p, pos);
128 	if (!key)
129 		return NULL;
130 	*_pos = key->serial;
131 	return &key->serial_node;
132 }
133 
134 static inline key_serial_t key_node_serial(struct rb_node *n)
135 {
136 	struct key *key = rb_entry(n, struct key, serial_node);
137 	return key->serial;
138 }
139 
140 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
141 {
142 	struct rb_node *n;
143 
144 	n = key_serial_next(p, v);
145 	if (n)
146 		*_pos = key_node_serial(n);
147 	return n;
148 }
149 
150 static void proc_keys_stop(struct seq_file *p, void *v)
151 	__releases(key_serial_lock)
152 {
153 	spin_unlock(&key_serial_lock);
154 }
155 
156 static int proc_keys_show(struct seq_file *m, void *v)
157 {
158 	struct rb_node *_p = v;
159 	struct key *key = rb_entry(_p, struct key, serial_node);
160 	unsigned long flags;
161 	key_ref_t key_ref, skey_ref;
162 	time64_t now, expiry;
163 	char xbuf[16];
164 	short state;
165 	u64 timo;
166 	int rc;
167 
168 	struct keyring_search_context ctx = {
169 		.index_key.type		= key->type,
170 		.index_key.description	= key->description,
171 		.cred			= m->file->f_cred,
172 		.match_data.cmp		= lookup_user_key_possessed,
173 		.match_data.raw_data	= key,
174 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
175 		.flags			= KEYRING_SEARCH_NO_STATE_CHECK,
176 	};
177 
178 	key_ref = make_key_ref(key, 0);
179 
180 	/* determine if the key is possessed by this process (a test we can
181 	 * skip if the key does not indicate the possessor can view it
182 	 */
183 	if (key->perm & KEY_POS_VIEW) {
184 		skey_ref = search_my_process_keyrings(&ctx);
185 		if (!IS_ERR(skey_ref)) {
186 			key_ref_put(skey_ref);
187 			key_ref = make_key_ref(key, 1);
188 		}
189 	}
190 
191 	/* check whether the current task is allowed to view the key */
192 	rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
193 	if (rc < 0)
194 		return 0;
195 
196 	now = ktime_get_real_seconds();
197 
198 	rcu_read_lock();
199 
200 	/* come up with a suitable timeout value */
201 	expiry = READ_ONCE(key->expiry);
202 	if (expiry == 0) {
203 		memcpy(xbuf, "perm", 5);
204 	} else if (now >= expiry) {
205 		memcpy(xbuf, "expd", 5);
206 	} else {
207 		timo = expiry - now;
208 
209 		if (timo < 60)
210 			sprintf(xbuf, "%llus", timo);
211 		else if (timo < 60*60)
212 			sprintf(xbuf, "%llum", div_u64(timo, 60));
213 		else if (timo < 60*60*24)
214 			sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
215 		else if (timo < 60*60*24*7)
216 			sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
217 		else
218 			sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
219 	}
220 
221 	state = key_read_state(key);
222 
223 #define showflag(FLAGS, LETTER, FLAG) \
224 	((FLAGS & (1 << FLAG)) ? LETTER : '-')
225 
226 	flags = READ_ONCE(key->flags);
227 	seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
228 		   key->serial,
229 		   state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
230 		   showflag(flags, 'R', KEY_FLAG_REVOKED),
231 		   showflag(flags, 'D', KEY_FLAG_DEAD),
232 		   showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
233 		   showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
234 		   state < 0 ? 'N' : '-',
235 		   showflag(flags, 'i', KEY_FLAG_INVALIDATED),
236 		   refcount_read(&key->usage),
237 		   xbuf,
238 		   key->perm,
239 		   from_kuid_munged(seq_user_ns(m), key->uid),
240 		   from_kgid_munged(seq_user_ns(m), key->gid),
241 		   key->type->name);
242 
243 #undef showflag
244 
245 	if (key->type->describe)
246 		key->type->describe(key, m);
247 	seq_putc(m, '\n');
248 
249 	rcu_read_unlock();
250 	return 0;
251 }
252 
253 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
254 {
255 	while (n) {
256 		struct key_user *user = rb_entry(n, struct key_user, node);
257 		if (kuid_has_mapping(user_ns, user->uid))
258 			break;
259 		n = rb_next(n);
260 	}
261 	return n;
262 }
263 
264 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
265 {
266 	return __key_user_next(user_ns, rb_next(n));
267 }
268 
269 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
270 {
271 	struct rb_node *n = rb_first(r);
272 	return __key_user_next(user_ns, n);
273 }
274 
275 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
276 	__acquires(key_user_lock)
277 {
278 	struct rb_node *_p;
279 	loff_t pos = *_pos;
280 
281 	spin_lock(&key_user_lock);
282 
283 	_p = key_user_first(seq_user_ns(p), &key_user_tree);
284 	while (pos > 0 && _p) {
285 		pos--;
286 		_p = key_user_next(seq_user_ns(p), _p);
287 	}
288 
289 	return _p;
290 }
291 
292 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
293 {
294 	(*_pos)++;
295 	return key_user_next(seq_user_ns(p), (struct rb_node *)v);
296 }
297 
298 static void proc_key_users_stop(struct seq_file *p, void *v)
299 	__releases(key_user_lock)
300 {
301 	spin_unlock(&key_user_lock);
302 }
303 
304 static int proc_key_users_show(struct seq_file *m, void *v)
305 {
306 	struct rb_node *_p = v;
307 	struct key_user *user = rb_entry(_p, struct key_user, node);
308 	unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
309 		key_quota_root_maxkeys : key_quota_maxkeys;
310 	unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
311 		key_quota_root_maxbytes : key_quota_maxbytes;
312 
313 	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
314 		   from_kuid_munged(seq_user_ns(m), user->uid),
315 		   refcount_read(&user->usage),
316 		   atomic_read(&user->nkeys),
317 		   atomic_read(&user->nikeys),
318 		   user->qnkeys,
319 		   maxkeys,
320 		   user->qnbytes,
321 		   maxbytes);
322 
323 	return 0;
324 }
325