Merge branch 'master' into next
[linux-2.6] / security / selinux / ss / sidtab.c
1 /*
2  * Implementation of the SID table type.
3  *
4  * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
5  */
6 #include <linux/kernel.h>
7 #include <linux/slab.h>
8 #include <linux/spinlock.h>
9 #include <linux/errno.h>
10 #include "flask.h"
11 #include "security.h"
12 #include "sidtab.h"
13
14 #define SIDTAB_HASH(sid) \
15 (sid & SIDTAB_HASH_MASK)
16
17 int sidtab_init(struct sidtab *s)
18 {
19         int i;
20
21         s->htable = kmalloc(sizeof(*(s->htable)) * SIDTAB_SIZE, GFP_ATOMIC);
22         if (!s->htable)
23                 return -ENOMEM;
24         for (i = 0; i < SIDTAB_SIZE; i++)
25                 s->htable[i] = NULL;
26         s->nel = 0;
27         s->next_sid = 1;
28         s->shutdown = 0;
29         spin_lock_init(&s->lock);
30         return 0;
31 }
32
33 int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
34 {
35         int hvalue, rc = 0;
36         struct sidtab_node *prev, *cur, *newnode;
37
38         if (!s) {
39                 rc = -ENOMEM;
40                 goto out;
41         }
42
43         hvalue = SIDTAB_HASH(sid);
44         prev = NULL;
45         cur = s->htable[hvalue];
46         while (cur && sid > cur->sid) {
47                 prev = cur;
48                 cur = cur->next;
49         }
50
51         if (cur && sid == cur->sid) {
52                 rc = -EEXIST;
53                 goto out;
54         }
55
56         newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
57         if (newnode == NULL) {
58                 rc = -ENOMEM;
59                 goto out;
60         }
61         newnode->sid = sid;
62         if (context_cpy(&newnode->context, context)) {
63                 kfree(newnode);
64                 rc = -ENOMEM;
65                 goto out;
66         }
67
68         if (prev) {
69                 newnode->next = prev->next;
70                 wmb();
71                 prev->next = newnode;
72         } else {
73                 newnode->next = s->htable[hvalue];
74                 wmb();
75                 s->htable[hvalue] = newnode;
76         }
77
78         s->nel++;
79         if (sid >= s->next_sid)
80                 s->next_sid = sid + 1;
81 out:
82         return rc;
83 }
84
85 static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
86 {
87         int hvalue;
88         struct sidtab_node *cur;
89
90         if (!s)
91                 return NULL;
92
93         hvalue = SIDTAB_HASH(sid);
94         cur = s->htable[hvalue];
95         while (cur && sid > cur->sid)
96                 cur = cur->next;
97
98         if (force && cur && sid == cur->sid && cur->context.len)
99                 return &cur->context;
100
101         if (cur == NULL || sid != cur->sid || cur->context.len) {
102                 /* Remap invalid SIDs to the unlabeled SID. */
103                 sid = SECINITSID_UNLABELED;
104                 hvalue = SIDTAB_HASH(sid);
105                 cur = s->htable[hvalue];
106                 while (cur && sid > cur->sid)
107                         cur = cur->next;
108                 if (!cur || sid != cur->sid)
109                         return NULL;
110         }
111
112         return &cur->context;
113 }
114
115 struct context *sidtab_search(struct sidtab *s, u32 sid)
116 {
117         return sidtab_search_core(s, sid, 0);
118 }
119
120 struct context *sidtab_search_force(struct sidtab *s, u32 sid)
121 {
122         return sidtab_search_core(s, sid, 1);
123 }
124
125 int sidtab_map(struct sidtab *s,
126                int (*apply) (u32 sid,
127                              struct context *context,
128                              void *args),
129                void *args)
130 {
131         int i, rc = 0;
132         struct sidtab_node *cur;
133
134         if (!s)
135                 goto out;
136
137         for (i = 0; i < SIDTAB_SIZE; i++) {
138                 cur = s->htable[i];
139                 while (cur) {
140                         rc = apply(cur->sid, &cur->context, args);
141                         if (rc)
142                                 goto out;
143                         cur = cur->next;
144                 }
145         }
146 out:
147         return rc;
148 }
149
150 static inline u32 sidtab_search_context(struct sidtab *s,
151                                                   struct context *context)
152 {
153         int i;
154         struct sidtab_node *cur;
155
156         for (i = 0; i < SIDTAB_SIZE; i++) {
157                 cur = s->htable[i];
158                 while (cur) {
159                         if (context_cmp(&cur->context, context))
160                                 return cur->sid;
161                         cur = cur->next;
162                 }
163         }
164         return 0;
165 }
166
167 int sidtab_context_to_sid(struct sidtab *s,
168                           struct context *context,
169                           u32 *out_sid)
170 {
171         u32 sid;
172         int ret = 0;
173         unsigned long flags;
174
175         *out_sid = SECSID_NULL;
176
177         sid = sidtab_search_context(s, context);
178         if (!sid) {
179                 spin_lock_irqsave(&s->lock, flags);
180                 /* Rescan now that we hold the lock. */
181                 sid = sidtab_search_context(s, context);
182                 if (sid)
183                         goto unlock_out;
184                 /* No SID exists for the context.  Allocate a new one. */
185                 if (s->next_sid == UINT_MAX || s->shutdown) {
186                         ret = -ENOMEM;
187                         goto unlock_out;
188                 }
189                 sid = s->next_sid++;
190                 if (context->len)
191                         printk(KERN_INFO
192                        "SELinux:  Context %s is not valid (left unmapped).\n",
193                                context->str);
194                 ret = sidtab_insert(s, sid, context);
195                 if (ret)
196                         s->next_sid--;
197 unlock_out:
198                 spin_unlock_irqrestore(&s->lock, flags);
199         }
200
201         if (ret)
202                 return ret;
203
204         *out_sid = sid;
205         return 0;
206 }
207
208 void sidtab_hash_eval(struct sidtab *h, char *tag)
209 {
210         int i, chain_len, slots_used, max_chain_len;
211         struct sidtab_node *cur;
212
213         slots_used = 0;
214         max_chain_len = 0;
215         for (i = 0; i < SIDTAB_SIZE; i++) {
216                 cur = h->htable[i];
217                 if (cur) {
218                         slots_used++;
219                         chain_len = 0;
220                         while (cur) {
221                                 chain_len++;
222                                 cur = cur->next;
223                         }
224
225                         if (chain_len > max_chain_len)
226                                 max_chain_len = chain_len;
227                 }
228         }
229
230         printk(KERN_DEBUG "%s:  %d entries and %d/%d buckets used, longest "
231                "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
232                max_chain_len);
233 }
234
235 void sidtab_destroy(struct sidtab *s)
236 {
237         int i;
238         struct sidtab_node *cur, *temp;
239
240         if (!s)
241                 return;
242
243         for (i = 0; i < SIDTAB_SIZE; i++) {
244                 cur = s->htable[i];
245                 while (cur) {
246                         temp = cur;
247                         cur = cur->next;
248                         context_destroy(&temp->context);
249                         kfree(temp);
250                 }
251                 s->htable[i] = NULL;
252         }
253         kfree(s->htable);
254         s->htable = NULL;
255         s->nel = 0;
256         s->next_sid = 1;
257 }
258
259 void sidtab_set(struct sidtab *dst, struct sidtab *src)
260 {
261         unsigned long flags;
262
263         spin_lock_irqsave(&src->lock, flags);
264         dst->htable = src->htable;
265         dst->nel = src->nel;
266         dst->next_sid = src->next_sid;
267         dst->shutdown = 0;
268         spin_unlock_irqrestore(&src->lock, flags);
269 }
270
271 void sidtab_shutdown(struct sidtab *s)
272 {
273         unsigned long flags;
274
275         spin_lock_irqsave(&s->lock, flags);
276         s->shutdown = 1;
277         spin_unlock_irqrestore(&s->lock, flags);
278 }