xref: /openbmc/linux/security/keys/proc.c (revision 84cc6674) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* procfs files for key database enumeration
3  *
4  * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/init.h>
9 #include <linux/sched.h>
10 #include <linux/fs.h>
11 #include <linux/proc_fs.h>
12 #include <linux/seq_file.h>
13 #include <asm/errno.h>
14 #include "internal.h"
15 
16 static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
17 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
18 static void proc_keys_stop(struct seq_file *p, void *v);
19 static int proc_keys_show(struct seq_file *m, void *v);
20 
21 static const struct seq_operations proc_keys_ops = {
22 	.start	= proc_keys_start,
23 	.next	= proc_keys_next,
24 	.stop	= proc_keys_stop,
25 	.show	= proc_keys_show,
26 };
27 
28 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
29 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
30 static void proc_key_users_stop(struct seq_file *p, void *v);
31 static int proc_key_users_show(struct seq_file *m, void *v);
32 
33 static const struct seq_operations proc_key_users_ops = {
34 	.start	= proc_key_users_start,
35 	.next	= proc_key_users_next,
36 	.stop	= proc_key_users_stop,
37 	.show	= proc_key_users_show,
38 };
39 
40 /*
41  * Declare the /proc files.
42  */
43 static int __init key_proc_init(void)
44 {
45 	struct proc_dir_entry *p;
46 
47 	p = proc_create_seq("keys", 0, NULL, &proc_keys_ops);
48 	if (!p)
49 		panic("Cannot create /proc/keys\n");
50 
51 	p = proc_create_seq("key-users", 0, NULL, &proc_key_users_ops);
52 	if (!p)
53 		panic("Cannot create /proc/key-users\n");
54 
55 	return 0;
56 }
57 
58 __initcall(key_proc_init);
59 
60 /*
61  * Implement "/proc/keys" to provide a list of the keys on the system that
62  * grant View permission to the caller.
63  */
64 static struct rb_node *key_serial_next(struct seq_file *p, struct rb_node *n)
65 {
66 	struct user_namespace *user_ns = seq_user_ns(p);
67 
68 	n = rb_next(n);
69 	while (n) {
70 		struct key *key = rb_entry(n, struct key, serial_node);
71 		if (kuid_has_mapping(user_ns, key->user->uid))
72 			break;
73 		n = rb_next(n);
74 	}
75 	return n;
76 }
77 
78 static struct key *find_ge_key(struct seq_file *p, key_serial_t id)
79 {
80 	struct user_namespace *user_ns = seq_user_ns(p);
81 	struct rb_node *n = key_serial_tree.rb_node;
82 	struct key *minkey = NULL;
83 
84 	while (n) {
85 		struct key *key = rb_entry(n, struct key, serial_node);
86 		if (id < key->serial) {
87 			if (!minkey || minkey->serial > key->serial)
88 				minkey = key;
89 			n = n->rb_left;
90 		} else if (id > key->serial) {
91 			n = n->rb_right;
92 		} else {
93 			minkey = key;
94 			break;
95 		}
96 		key = NULL;
97 	}
98 
99 	if (!minkey)
100 		return NULL;
101 
102 	for (;;) {
103 		if (kuid_has_mapping(user_ns, minkey->user->uid))
104 			return minkey;
105 		n = rb_next(&minkey->serial_node);
106 		if (!n)
107 			return NULL;
108 		minkey = rb_entry(n, struct key, serial_node);
109 	}
110 }
111 
112 static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
113 	__acquires(key_serial_lock)
114 {
115 	key_serial_t pos = *_pos;
116 	struct key *key;
117 
118 	spin_lock(&key_serial_lock);
119 
120 	if (*_pos > INT_MAX)
121 		return NULL;
122 	key = find_ge_key(p, pos);
123 	if (!key)
124 		return NULL;
125 	*_pos = key->serial;
126 	return &key->serial_node;
127 }
128 
129 static inline key_serial_t key_node_serial(struct rb_node *n)
130 {
131 	struct key *key = rb_entry(n, struct key, serial_node);
132 	return key->serial;
133 }
134 
135 static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
136 {
137 	struct rb_node *n;
138 
139 	n = key_serial_next(p, v);
140 	if (n)
141 		*_pos = key_node_serial(n);
142 	else
143 		(*_pos)++;
144 	return n;
145 }
146 
147 static void proc_keys_stop(struct seq_file *p, void *v)
148 	__releases(key_serial_lock)
149 {
150 	spin_unlock(&key_serial_lock);
151 }
152 
153 static int proc_keys_show(struct seq_file *m, void *v)
154 {
155 	struct rb_node *_p = v;
156 	struct key *key = rb_entry(_p, struct key, serial_node);
157 	unsigned long flags;
158 	key_ref_t key_ref, skey_ref;
159 	time64_t now, expiry;
160 	char xbuf[16];
161 	short state;
162 	u64 timo;
163 	int rc;
164 
165 	struct keyring_search_context ctx = {
166 		.index_key		= key->index_key,
167 		.cred			= m->file->f_cred,
168 		.match_data.cmp		= lookup_user_key_possessed,
169 		.match_data.raw_data	= key,
170 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
171 		.flags			= (KEYRING_SEARCH_NO_STATE_CHECK |
172 					   KEYRING_SEARCH_RECURSE),
173 	};
174 
175 	key_ref = make_key_ref(key, 0);
176 
177 	/* determine if the key is possessed by this process (a test we can
178 	 * skip if the key does not indicate the possessor can view it
179 	 */
180 	if (key->perm & KEY_POS_VIEW) {
181 		rcu_read_lock();
182 		skey_ref = search_cred_keyrings_rcu(&ctx);
183 		rcu_read_unlock();
184 		if (!IS_ERR(skey_ref)) {
185 			key_ref_put(skey_ref);
186 			key_ref = make_key_ref(key, 1);
187 		}
188 	}
189 
190 	/* check whether the current task is allowed to view the key */
191 	rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
192 	if (rc < 0)
193 		return 0;
194 
195 	now = ktime_get_real_seconds();
196 
197 	rcu_read_lock();
198 
199 	/* come up with a suitable timeout value */
200 	expiry = READ_ONCE(key->expiry);
201 	if (expiry == 0) {
202 		memcpy(xbuf, "perm", 5);
203 	} else if (now >= expiry) {
204 		memcpy(xbuf, "expd", 5);
205 	} else {
206 		timo = expiry - now;
207 
208 		if (timo < 60)
209 			sprintf(xbuf, "%llus", timo);
210 		else if (timo < 60*60)
211 			sprintf(xbuf, "%llum", div_u64(timo, 60));
212 		else if (timo < 60*60*24)
213 			sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
214 		else if (timo < 60*60*24*7)
215 			sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
216 		else
217 			sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
218 	}
219 
220 	state = key_read_state(key);
221 
222 #define showflag(FLAGS, LETTER, FLAG) \
223 	((FLAGS & (1 << FLAG)) ? LETTER : '-')
224 
225 	flags = READ_ONCE(key->flags);
226 	seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
227 		   key->serial,
228 		   state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
229 		   showflag(flags, 'R', KEY_FLAG_REVOKED),
230 		   showflag(flags, 'D', KEY_FLAG_DEAD),
231 		   showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
232 		   showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
233 		   state < 0 ? 'N' : '-',
234 		   showflag(flags, 'i', KEY_FLAG_INVALIDATED),
235 		   refcount_read(&key->usage),
236 		   xbuf,
237 		   key->perm,
238 		   from_kuid_munged(seq_user_ns(m), key->uid),
239 		   from_kgid_munged(seq_user_ns(m), key->gid),
240 		   key->type->name);
241 
242 #undef showflag
243 
244 	if (key->type->describe)
245 		key->type->describe(key, m);
246 	seq_putc(m, '\n');
247 
248 	rcu_read_unlock();
249 	return 0;
250 }
251 
252 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
253 {
254 	while (n) {
255 		struct key_user *user = rb_entry(n, struct key_user, node);
256 		if (kuid_has_mapping(user_ns, user->uid))
257 			break;
258 		n = rb_next(n);
259 	}
260 	return n;
261 }
262 
263 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
264 {
265 	return __key_user_next(user_ns, rb_next(n));
266 }
267 
268 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
269 {
270 	struct rb_node *n = rb_first(r);
271 	return __key_user_next(user_ns, n);
272 }
273 
274 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
275 	__acquires(key_user_lock)
276 {
277 	struct rb_node *_p;
278 	loff_t pos = *_pos;
279 
280 	spin_lock(&key_user_lock);
281 
282 	_p = key_user_first(seq_user_ns(p), &key_user_tree);
283 	while (pos > 0 && _p) {
284 		pos--;
285 		_p = key_user_next(seq_user_ns(p), _p);
286 	}
287 
288 	return _p;
289 }
290 
291 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
292 {
293 	(*_pos)++;
294 	return key_user_next(seq_user_ns(p), (struct rb_node *)v);
295 }
296 
297 static void proc_key_users_stop(struct seq_file *p, void *v)
298 	__releases(key_user_lock)
299 {
300 	spin_unlock(&key_user_lock);
301 }
302 
303 static int proc_key_users_show(struct seq_file *m, void *v)
304 {
305 	struct rb_node *_p = v;
306 	struct key_user *user = rb_entry(_p, struct key_user, node);
307 	unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
308 		key_quota_root_maxkeys : key_quota_maxkeys;
309 	unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
310 		key_quota_root_maxbytes : key_quota_maxbytes;
311 
312 	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
313 		   from_kuid_munged(seq_user_ns(m), user->uid),
314 		   refcount_read(&user->usage),
315 		   atomic_read(&user->nkeys),
316 		   atomic_read(&user->nikeys),
317 		   user->qnkeys,
318 		   maxkeys,
319 		   user->qnbytes,
320 		   maxbytes);
321 
322 	return 0;
323 }
324