/* * 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); }