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 #define INIT_SIDTAB_LOCK(s) spin_lock_init(&s->lock)
  18 #define SIDTAB_LOCK(s, x) spin_lock_irqsave(&s->lock, x)
  19 #define SIDTAB_UNLOCK(s, x) spin_unlock_irqrestore(&s->lock, x)
  20
  21 int sidtab_init(struct sidtab *s)
  22 {
  23         int i;
  24
  25         s->htable = kmalloc(sizeof(*(s->htable)) * SIDTAB_SIZE, GFP_ATOMIC);
  26         if (!s->htable)
  27                 return -ENOMEM;
  28         for (i = 0; i < SIDTAB_SIZE; i++)
  29                 s->htable[i] = NULL;
  30         s->nel = 0;
  31         s->next_sid = 1;
  32         s->shutdown = 0;
  33         INIT_SIDTAB_LOCK(s);
  34         return 0;
  35 }
  36
  37 int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
  38 {
  39         int hvalue, rc = 0;
  40         struct sidtab_node *prev, *cur, *newnode;
  41
  42         if (!s) {
  43                 rc = -ENOMEM;
  44                 goto out;
  45         }
  46
  47         hvalue = SIDTAB_HASH(sid);
  48         prev = NULL;
  49         cur = s->htable[hvalue];
  50         while (cur != NULL && sid > cur->sid) {
  51                 prev = cur;
  52                 cur = cur->next;
  53         }
  54
  55         if (cur && sid == cur->sid) {
  56                 rc = -EEXIST;
  57                 goto out;
  58         }
  59
  60         newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
  61         if (newnode == NULL) {
  62                 rc = -ENOMEM;
  63                 goto out;
  64         }
  65         newnode->sid = sid;
  66         if (context_cpy(&newnode->context, context)) {
  67                 kfree(newnode);
  68                 rc = -ENOMEM;
  69                 goto out;
  70         }
  71
  72         if (prev) {
  73                 newnode->next = prev->next;
  74                 wmb();
  75                 prev->next = newnode;
  76         } else {
  77                 newnode->next = s->htable[hvalue];
  78                 wmb();
  79                 s->htable[hvalue] = newnode;
  80         }
  81
  82         s->nel++;
  83         if (sid >= s->next_sid)
  84                 s->next_sid = sid + 1;
  85 out:
  86         return rc;
  87 }
  88
  89 struct context *sidtab_search(struct sidtab *s, u32 sid)
  90 {
  91         int hvalue;
  92         struct sidtab_node *cur;
  93
  94         if (!s)
  95                 return NULL;
  96
  97         hvalue = SIDTAB_HASH(sid);
  98         cur = s->htable[hvalue];
  99         while (cur != NULL && sid > cur->sid)
 100                 cur = cur->next;
 101
 102         if (cur == NULL || sid != cur->sid) {
 103                 /* Remap invalid SIDs to the unlabeled SID. */
 104                 sid = SECINITSID_UNLABELED;
 105                 hvalue = SIDTAB_HASH(sid);
 106                 cur = s->htable[hvalue];
 107                 while (cur != NULL && sid > cur->sid)
 108                         cur = cur->next;
 109                 if (!cur || sid != cur->sid)
 110                         return NULL;
 111         }
 112
 113         return &cur->context;
 114 }
 115
 116 int sidtab_map(struct sidtab *s,
 117                int (*apply) (u32 sid,
 118                              struct context *context,
 119                              void *args),
 120                void *args)
 121 {
 122         int i, rc = 0;
 123         struct sidtab_node *cur;
 124
 125         if (!s)
 126                 goto out;
 127
 128         for (i = 0; i < SIDTAB_SIZE; i++) {
 129                 cur = s->htable[i];
 130                 while (cur != NULL) {
 131                         rc = apply(cur->sid, &cur->context, args);
 132                         if (rc)
 133                                 goto out;
 134                         cur = cur->next;
 135                 }
 136         }
 137 out:
 138         return rc;
 139 }
 140
 141 void sidtab_map_remove_on_error(struct sidtab *s,
 142                                 int (*apply) (u32 sid,
 143                                               struct context *context,
 144                                               void *args),
 145                                 void *args)
 146 {
 147         int i, ret;
 148         struct sidtab_node *last, *cur, *temp;
 149
 150         if (!s)
 151                 return;
 152
 153         for (i = 0; i < SIDTAB_SIZE; i++) {
 154                 last = NULL;
 155                 cur = s->htable[i];
 156                 while (cur != NULL) {
 157                         ret = apply(cur->sid, &cur->context, args);
 158                         if (ret) {
 159                                 if (last)
 160                                         last->next = cur->next;
 161                                 else
 162                                         s->htable[i] = cur->next;
 163                                 temp = cur;
 164                                 cur = cur->next;
 165                                 context_destroy(&temp->context);
 166                                 kfree(temp);
 167                                 s->nel--;
 168                         } else {
 169                                 last = cur;
 170                                 cur = cur->next;
 171                         }
 172                 }
 173         }
 174
 175         return;
 176 }
 177
 178 static inline u32 sidtab_search_context(struct sidtab *s,
 179                                                   struct context *context)
 180 {
 181         int i;
 182         struct sidtab_node *cur;
 183
 184         for (i = 0; i < SIDTAB_SIZE; i++) {
 185                 cur = s->htable[i];
 186                 while (cur != NULL) {
 187                         if (context_cmp(&cur->context, context))
 188                                 return cur->sid;
 189                         cur = cur->next;
 190                 }
 191         }
 192         return 0;
 193 }
 194
 195 int sidtab_context_to_sid(struct sidtab *s,
 196                           struct context *context,
 197                           u32 *out_sid)
 198 {
 199         u32 sid;
 200         int ret = 0;
 201         unsigned long flags;
 202
 203         *out_sid = SECSID_NULL;
 204
 205         sid = sidtab_search_context(s, context);
 206         if (!sid) {
 207                 SIDTAB_LOCK(s, flags);
 208                 /* Rescan now that we hold the lock. */
 209                 sid = sidtab_search_context(s, context);
 210                 if (sid)
 211                         goto unlock_out;
 212                 /* No SID exists for the context.  Allocate a new one. */
 213                 if (s->next_sid == UINT_MAX || s->shutdown) {
 214                         ret = -ENOMEM;
 215                         goto unlock_out;
 216                 }
 217                 sid = s->next_sid++;
 218                 ret = sidtab_insert(s, sid, context);
 219                 if (ret)
 220                         s->next_sid--;
 221 unlock_out:
 222                 SIDTAB_UNLOCK(s, flags);
 223         }
 224
 225         if (ret)
 226                 return ret;
 227
 228         *out_sid = sid;
 229         return 0;
 230 }
 231
 232 void sidtab_hash_eval(struct sidtab *h, char *tag)
 233 {
 234         int i, chain_len, slots_used, max_chain_len;
 235         struct sidtab_node *cur;
 236
 237         slots_used = 0;
 238         max_chain_len = 0;
 239         for (i = 0; i < SIDTAB_SIZE; i++) {
 240                 cur = h->htable[i];
 241                 if (cur) {
 242                         slots_used++;
 243                         chain_len = 0;
 244                         while (cur) {
 245                                 chain_len++;
 246                                 cur = cur->next;
 247                         }
 248
 249                         if (chain_len > max_chain_len)
 250                                 max_chain_len = chain_len;
 251                 }
 252         }
 253
 254         printk(KERN_DEBUG "%s:  %d entries and %d/%d buckets used, longest "
 255                "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
 256                max_chain_len);
 257 }
 258
 259 void sidtab_destroy(struct sidtab *s)
 260 {
 261         int i;
 262         struct sidtab_node *cur, *temp;
 263
 264         if (!s)
 265                 return;
 266
 267         for (i = 0; i < SIDTAB_SIZE; i++) {
 268                 cur = s->htable[i];
 269                 while (cur != NULL) {
 270                         temp = cur;
 271                         cur = cur->next;
 272                         context_destroy(&temp->context);
 273                         kfree(temp);
 274                 }
 275                 s->htable[i] = NULL;
 276         }
 277         kfree(s->htable);
 278         s->htable = NULL;
 279         s->nel = 0;
 280         s->next_sid = 1;
 281 }
 282
 283 void sidtab_set(struct sidtab *dst, struct sidtab *src)
 284 {
 285         unsigned long flags;
 286
 287         SIDTAB_LOCK(src, flags);
 288         dst->htable = src->htable;
 289         dst->nel = src->nel;
 290         dst->next_sid = src->next_sid;
 291         dst->shutdown = 0;
 292         SIDTAB_UNLOCK(src, flags);
 293 }
 294
 295 void sidtab_shutdown(struct sidtab *s)
 296 {
 297         unsigned long flags;
 298
 299         SIDTAB_LOCK(s, flags);
 300         s->shutdown = 1;
 301         SIDTAB_UNLOCK(s, flags);
 302 }