xref: /openbmc/linux/security/keys/proc.c (revision 9726bfcd) 
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 	return n;
143 }
144 
145 static void proc_keys_stop(struct seq_file *p, void *v)
146 	__releases(key_serial_lock)
147 {
148 	spin_unlock(&key_serial_lock);
149 }
150 
151 static int proc_keys_show(struct seq_file *m, void *v)
152 {
153 	struct rb_node *_p = v;
154 	struct key *key = rb_entry(_p, struct key, serial_node);
155 	unsigned long flags;
156 	key_ref_t key_ref, skey_ref;
157 	time64_t now, expiry;
158 	char xbuf[16];
159 	short state;
160 	u64 timo;
161 	int rc;
162 
163 	struct keyring_search_context ctx = {
164 		.index_key		= key->index_key,
165 		.cred			= m->file->f_cred,
166 		.match_data.cmp		= lookup_user_key_possessed,
167 		.match_data.raw_data	= key,
168 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
169 		.flags			= (KEYRING_SEARCH_NO_STATE_CHECK |
170 					   KEYRING_SEARCH_RECURSE),
171 	};
172 
173 	key_ref = make_key_ref(key, 0);
174 
175 	/* determine if the key is possessed by this process (a test we can
176 	 * skip if the key does not indicate the possessor can view it
177 	 */
178 	if (key->perm & KEY_POS_VIEW) {
179 		rcu_read_lock();
180 		skey_ref = search_cred_keyrings_rcu(&ctx);
181 		rcu_read_unlock();
182 		if (!IS_ERR(skey_ref)) {
183 			key_ref_put(skey_ref);
184 			key_ref = make_key_ref(key, 1);
185 		}
186 	}
187 
188 	/* check whether the current task is allowed to view the key */
189 	rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
190 	if (rc < 0)
191 		return 0;
192 
193 	now = ktime_get_real_seconds();
194 
195 	rcu_read_lock();
196 
197 	/* come up with a suitable timeout value */
198 	expiry = READ_ONCE(key->expiry);
199 	if (expiry == 0) {
200 		memcpy(xbuf, "perm", 5);
201 	} else if (now >= expiry) {
202 		memcpy(xbuf, "expd", 5);
203 	} else {
204 		timo = expiry - now;
205 
206 		if (timo < 60)
207 			sprintf(xbuf, "%llus", timo);
208 		else if (timo < 60*60)
209 			sprintf(xbuf, "%llum", div_u64(timo, 60));
210 		else if (timo < 60*60*24)
211 			sprintf(xbuf, "%lluh", div_u64(timo, 60 * 60));
212 		else if (timo < 60*60*24*7)
213 			sprintf(xbuf, "%llud", div_u64(timo, 60 * 60 * 24));
214 		else
215 			sprintf(xbuf, "%lluw", div_u64(timo, 60 * 60 * 24 * 7));
216 	}
217 
218 	state = key_read_state(key);
219 
220 #define showflag(FLAGS, LETTER, FLAG) \
221 	((FLAGS & (1 << FLAG)) ? LETTER : '-')
222 
223 	flags = READ_ONCE(key->flags);
224 	seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
225 		   key->serial,
226 		   state != KEY_IS_UNINSTANTIATED ? 'I' : '-',
227 		   showflag(flags, 'R', KEY_FLAG_REVOKED),
228 		   showflag(flags, 'D', KEY_FLAG_DEAD),
229 		   showflag(flags, 'Q', KEY_FLAG_IN_QUOTA),
230 		   showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT),
231 		   state < 0 ? 'N' : '-',
232 		   showflag(flags, 'i', KEY_FLAG_INVALIDATED),
233 		   refcount_read(&key->usage),
234 		   xbuf,
235 		   key->perm,
236 		   from_kuid_munged(seq_user_ns(m), key->uid),
237 		   from_kgid_munged(seq_user_ns(m), key->gid),
238 		   key->type->name);
239 
240 #undef showflag
241 
242 	if (key->type->describe)
243 		key->type->describe(key, m);
244 	seq_putc(m, '\n');
245 
246 	rcu_read_unlock();
247 	return 0;
248 }
249 
250 static struct rb_node *__key_user_next(struct user_namespace *user_ns, struct rb_node *n)
251 {
252 	while (n) {
253 		struct key_user *user = rb_entry(n, struct key_user, node);
254 		if (kuid_has_mapping(user_ns, user->uid))
255 			break;
256 		n = rb_next(n);
257 	}
258 	return n;
259 }
260 
261 static struct rb_node *key_user_next(struct user_namespace *user_ns, struct rb_node *n)
262 {
263 	return __key_user_next(user_ns, rb_next(n));
264 }
265 
266 static struct rb_node *key_user_first(struct user_namespace *user_ns, struct rb_root *r)
267 {
268 	struct rb_node *n = rb_first(r);
269 	return __key_user_next(user_ns, n);
270 }
271 
272 static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
273 	__acquires(key_user_lock)
274 {
275 	struct rb_node *_p;
276 	loff_t pos = *_pos;
277 
278 	spin_lock(&key_user_lock);
279 
280 	_p = key_user_first(seq_user_ns(p), &key_user_tree);
281 	while (pos > 0 && _p) {
282 		pos--;
283 		_p = key_user_next(seq_user_ns(p), _p);
284 	}
285 
286 	return _p;
287 }
288 
289 static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
290 {
291 	(*_pos)++;
292 	return key_user_next(seq_user_ns(p), (struct rb_node *)v);
293 }
294 
295 static void proc_key_users_stop(struct seq_file *p, void *v)
296 	__releases(key_user_lock)
297 {
298 	spin_unlock(&key_user_lock);
299 }
300 
301 static int proc_key_users_show(struct seq_file *m, void *v)
302 {
303 	struct rb_node *_p = v;
304 	struct key_user *user = rb_entry(_p, struct key_user, node);
305 	unsigned maxkeys = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
306 		key_quota_root_maxkeys : key_quota_maxkeys;
307 	unsigned maxbytes = uid_eq(user->uid, GLOBAL_ROOT_UID) ?
308 		key_quota_root_maxbytes : key_quota_maxbytes;
309 
310 	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
311 		   from_kuid_munged(seq_user_ns(m), user->uid),
312 		   refcount_read(&user->usage),
313 		   atomic_read(&user->nkeys),
314 		   atomic_read(&user->nikeys),
315 		   user->qnkeys,
316 		   maxkeys,
317 		   user->qnbytes,
318 		   maxbytes);
319 
320 	return 0;
321 }
322