aboutsummaryrefslogtreecommitdiffstats
path: root/security/selinux/ss/sidtab.c
blob: 871c33bd0741315638ef15dce4ef1e888850246b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
/*
 * Implementation of the SID table type.
 *
 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include "flask.h"
#include "security.h"
#include "sidtab.h"

#define SIDTAB_HASH(sid) \
(sid & SIDTAB_HASH_MASK)

#define INIT_SIDTAB_LOCK(s) spin_lock_init(&s->lock)
#define SIDTAB_LOCK(s, x) spin_lock_irqsave(&s->lock, x)
#define SIDTAB_UNLOCK(s, x) spin_unlock_irqrestore(&s->lock, x)

int sidtab_init(struct sidtab *s)
{
	int i;

	s->htable = kmalloc(sizeof(*(s->htable)) * SIDTAB_SIZE, GFP_ATOMIC);
	if (!s->htable)
		return -ENOMEM;
	for (i = 0; i < SIDTAB_SIZE; i++)
		s->htable[i] = NULL;
	s->nel = 0;
	s->next_sid = 1;
	s->shutdown = 0;
	INIT_SIDTAB_LOCK(s);
	return 0;
}

int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
{
	int hvalue, rc = 0;
	struct sidtab_node *prev, *cur, *newnode;

	if (!s) {
		rc = -ENOMEM;
		goto out;
	}

	hvalue = SIDTAB_HASH(sid);
	prev = NULL;
	cur = s->htable[hvalue];
	while (cur != NULL && sid > cur->sid) {
		prev = cur;
		cur = cur->next;
	}

	if (cur && sid == cur->sid) {
		rc = -EEXIST;
		goto out;
	}

	newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
	if (newnode == NULL) {
		rc = -ENOMEM;
		goto out;
	}
	newnode->sid = sid;
	if (context_cpy(&newnode->context, context)) {
		kfree(newnode);
		rc = -ENOMEM;
		goto out;
	}

	if (prev) {
		newnode->next = prev->next;
		wmb();
		prev->next = newnode;
	} else {
		newnode->next = s->htable[hvalue];
		wmb();
		s->htable[hvalue] = newnode;
	}

	s->nel++;
	if (sid >= s->next_sid)
		s->next_sid = sid + 1;
out:
	return rc;
}

struct context *sidtab_search(struct sidtab *s, u32 sid)
{
	int hvalue;
	struct sidtab_node *cur;

	if (!s)
		return NULL;

	hvalue = SIDTAB_HASH(sid);
	cur = s->htable[hvalue];
	while (cur != NULL && sid > cur->sid)
		cur = cur->next;

	if (cur == NULL || sid != cur->sid) {
		/* Remap invalid SIDs to the unlabeled SID. */
		sid = SECINITSID_UNLABELED;
		hvalue = SIDTAB_HASH(sid);
		cur = s->htable[hvalue];
		while (cur != NULL && sid > cur->sid)
			cur = cur->next;
		if (!cur || sid != cur->sid)
			return NULL;
	}

	return &cur->context;
}

int sidtab_map(struct sidtab *s,
	       int (*apply) (u32 sid,
			     struct context *context,
			     void *args),
	       void *args)
{
	int i, rc = 0;
	struct sidtab_node *cur;

	if (!s)
		goto out;

	for (i = 0; i < SIDTAB_SIZE; i++) {
		cur = s->htable[i];
		while (cur != NULL) {
			rc = apply(cur->sid, &cur->context, args);
			if (rc)
				goto out;
			cur = cur->next;
		}
	}
out:
	return rc;
}

void sidtab_map_remove_on_error(struct sidtab *s,
				int (*apply) (u32 sid,
					      struct context *context,
					      void *args),
				void *args)
{
	int i, ret;
	struct sidtab_node *last, *cur, *temp;

	if (!s)
		return;

	for (i = 0; i < SIDTAB_SIZE; i++) {
		last = NULL;
		cur = s->htable[i];
		while (cur != NULL) {
			ret = apply(cur->sid, &cur->context, args);
			if (ret) {
				if (last) {
					last->next = cur->next;
				} else {
					s->htable[i] = cur->next;
				}

				temp = cur;
				cur = cur->next;
				context_destroy(&temp->context);
				kfree(temp);
				s->nel--;
			} else {
				last = cur;
				cur = cur->next;
			}
		}
	}

	return;
}

static inline u32 sidtab_search_context(struct sidtab *s,
						  struct context *context)
{
	int i;
	struct sidtab_node *cur;

	for (i = 0; i < SIDTAB_SIZE; i++) {
		cur = s->htable[i];
		while (cur != NULL) {
			if (context_cmp(&cur->context, context))
				return cur->sid;
			cur = cur->next;
		}
	}
	return 0;
}

int sidtab_context_to_sid(struct sidtab *s,
			  struct context *context,
			  u32 *out_sid)
{
	u32 sid;
	int ret = 0;
	unsigned long flags;

	*out_sid = SECSID_NULL;

	sid = sidtab_search_context(s, context);
	if (!sid) {
		SIDTAB_LOCK(s, flags);
		/* Rescan now that we hold the lock. */
		sid = sidtab_search_context(s, context);
		if (sid)
			goto unlock_out;
		/* No SID exists for the context.  Allocate a new one. */
		if (s->next_sid == UINT_MAX || s->shutdown) {
			ret = -ENOMEM;
			goto unlock_out;
		}
		sid = s->next_sid++;
		ret = sidtab_insert(s, sid, context);
		if (ret)
			s->next_sid--;
unlock_out:
		SIDTAB_UNLOCK(s, flags);
	}

	if (ret)
		return ret;

	*out_sid = sid;
	return 0;
}

void sidtab_hash_eval(struct sidtab *h, char *tag)
{
	int i, chain_len, slots_used, max_chain_len;
	struct sidtab_node *cur;

	slots_used = 0;
	max_chain_len = 0;
	for (i = 0; i < SIDTAB_SIZE; i++) {
		cur = h->htable[i];
		if (cur) {
			slots_used++;
			chain_len = 0;
			while (cur) {
				chain_len++;
				cur = cur->next;
			}

			if (chain_len > max_chain_len)
				max_chain_len = chain_len;
		}
	}

	printk(KERN_INFO "%s:  %d entries and %d/%d buckets used, longest "
	       "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
	       max_chain_len);
}

void sidtab_destroy(struct sidtab *s)
{
	int i;
	struct sidtab_node *cur, *temp;

	if (!s)
		return;

	for (i = 0; i < SIDTAB_SIZE; i++) {
		cur = s->htable[i];
		while (cur != NULL) {
			temp = cur;
			cur = cur->next;
			context_destroy(&temp->context);
			kfree(temp);
		}
		s->htable[i] = NULL;
	}
	kfree(s->htable);
	s->htable = NULL;
	s->nel = 0;
	s->next_sid = 1;
}

void sidtab_set(struct sidtab *dst, struct sidtab *src)
{
	unsigned long flags;

	SIDTAB_LOCK(src, flags);
	dst->htable = src->htable;
	dst->nel = src->nel;
	dst->next_sid = src->next_sid;
	dst->shutdown = 0;
	SIDTAB_UNLOCK(src, flags);
}

void sidtab_shutdown(struct sidtab *s)
{
	unsigned long flags;

	SIDTAB_LOCK(s, flags);
	s->shutdown = 1;
	SIDTAB_UNLOCK(s, flags);
}

Privacy Policy