/* Authors: Karl MacMillan <kmacmillan@tresys.com>
* Frank Mayer <mayerf@tresys.com>
*
* Copyright (C) 2003 - 2004 Tresys Technology, LLC
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <asm/semaphore.h>
#include <linux/slab.h>
#include "security.h"
#include "conditional.h"
/*
* cond_evaluate_expr evaluates a conditional expr
* in reverse polish notation. It returns true (1), false (0),
* or undefined (-1). Undefined occurs when the expression
* exceeds the stack depth of COND_EXPR_MAXDEPTH.
*/
static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
{
struct cond_expr *cur;
int s[COND_EXPR_MAXDEPTH];
int sp = -1;
for (cur = expr; cur != NULL; cur = cur->next) {
switch (cur->expr_type) {
case COND_BOOL:
if (sp == (COND_EXPR_MAXDEPTH - 1))
return -1;
sp++;
s[sp] = p->bool_val_to_struct[cur->bool - 1]->state;
break;
case COND_NOT:
if (sp < 0)
return -1;
s[sp] = !s[sp];
break;
case COND_OR:
if (sp < 1)
return -1;
sp--;
s[sp] |= s[sp + 1];
break;
case COND_AND:
if (sp < 1)
return -1;
sp--;
s[sp] &= s[sp + 1];
break;
case COND_XOR:
if (sp < 1)
return -1;
sp--;
s[sp] ^= s[sp + 1];
break;
case COND_EQ:
if (sp < 1)
return -1;
sp--;
s[sp] = (s[sp] == s[sp + 1]);
break;
case COND_NEQ:
if (sp < 1)
return -1;
sp--;
s[sp] = (s[sp] != s[sp + 1]);
break;
default:
return -1;
}
}
return s[0];
}
/*
* evaluate_cond_node evaluates the conditional stored in
* a struct cond_node and if the result is different than the
* current state of the node it sets the rules in the true/false
* list appropriately. If the result of the expression is undefined
* all of the rules are disabled for safety.
*/
int evaluate_cond_node(struct policydb *p, struct cond_node *node)
{
int new_state;
struct cond_av_list* cur;
new_state = cond_evaluate_expr(p, node->expr);
if (new_state != node->cur_state) {
node->cur_state = new_state;
if (new_state == -1)
printk(KERN_ERR "security: expression result was undefined - disabling all rules.\n");
/* turn the rules on or off */
for (cur = node->true_list; cur != NULL; cur = cur->next) {
if (new_state <= 0) {
cur->node->datum.specified &= ~AVTAB_ENABLED;
} else {
cur->node->datum.specified |= AVTAB_ENABLED;
}
}
for (cur = node->false_list; cur != NULL; cur = cur->next) {
/* -1 or 1 */
if (new_state) {
cur->node->datum.specified &= ~AVTAB_ENABLED;
} else {
cur->node->datum.specified |= AVTAB_ENABLED;
}
}
}
return 0;
}
int cond_policydb_init(struct policydb *p)
{
p->bool_val_to_struct = NULL;
p->cond_list = NULL;
if (avtab_init(&p->te_cond_avtab))
return -1;
return 0;
}
static void cond_av_list_destroy(struct cond_av_list *list)
{
struct cond_av_list *cur, *next;
for (cur = list; cur != NULL; cur = next) {
next = cur->next;
/* the avtab_ptr_t node is destroy by the avtab */
kfree(cur);
}
}
static void cond_node_destroy(struct cond_node *node)
{
struct cond_expr *cur_expr, *next_expr;
for (cur_expr = node->expr; cur_expr != NULL; cur_expr = next_expr) {
next_expr = cur_expr->next;
kfree(cur_expr);
}
cond_av_list_destroy(node->true_list);
cond_av_list_destroy(node->false_list);
kfree(node);
}
static void cond_list_destroy(struct cond_node *list)
{
struct cond_node *next, *cur;
if (list == NULL)
return;
for (cur = list; cur != NULL; cur = next) {
next = cur->next;
cond_node_destroy(cur);
}
}
void cond_policydb_destroy(struct policydb *p)
{
if (p->bool_val_to_struct != NULL)
kfree(p->bool_val_to_struct);
avtab_destroy(&p->te_cond_avtab);
cond_list_destroy(p->cond_list);
}
int cond_init_bool_indexes(struct policydb *p)
{
if (p->bool_val_to_struct)
kfree(p->bool_val_to_struct);
p->bool_val_to_struct = (struct cond_bool_datum**)
kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum*), GFP_KERNEL);
if (!p->bool_val_to_struct)
return -1;
return 0;
}
int cond_destroy_bool(void *key, void *datum, void *p)
{
if (key)
kfree(key);
kfree(datum);
return 0;
}
int cond_index_bool(void *key, void *datum, void *datap)
{
struct policydb *p;
struct cond_bool_datum *booldatum;
booldatum = datum;
p = datap;
if (!booldatum->value || booldatum->value > p->p_bools.nprim)
return -EINVAL;
p->p_bool_val_to_name[booldatum->value - 1] = key;
p->bool_val_to_struct[booldatum->value -1] = booldatum;
return 0;
}
static int bool_isvalid(struct cond_bool_datum *b)
{
if (!(b->state == 0 || b->state == 1))
return 0;
return 1;
}
int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp)
{
char *key = NULL;
struct cond_bool_datum *booldatum;
u32 buf[3], len;
int rc;
booldatum = kmalloc(sizeof(struct cond_bool_datum), GFP_KERNEL);
if (!booldatum)
return -1;
memset(booldatum, 0, sizeof(struct cond_bool_datum));
rc = next_entry(buf, fp, sizeof buf);
if (rc < 0)
goto err;
booldatum->value = le32_to_cpu(buf[0]);
booldatum->state = le32_to_cpu(buf[1]);
if (!bool_isvalid(booldatum))
goto err;
len = le32_to_cpu(buf[2]);
key = kmalloc(len + 1, GFP_KERNEL);
if (!key)
goto err;
rc = next_entry(key, fp, len);
if (rc < 0)
goto err;
key[len] = 0;
if (hashtab_insert(h, key, booldatum))
goto err;
return 0;
err:
cond_destroy_bool(key, booldatum, NULL);
return -1;
}
static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list,
struct cond_av_list *other)
{
struct cond_av_list *list, *last = NULL, *cur;
struct avtab_key key;
struct avtab_datum datum;
struct avtab_node *node_ptr;
int rc;
u32 buf[1], i, len;
u8 found;
*ret_list = NULL;
len = 0;
rc = next_entry(buf, fp, sizeof buf);
if (rc < 0)
return -1;
len = le32_to_cpu(buf[0]);
if (len == 0) {
return 0;
}
for (i = 0; i < len; i++) {
if (avtab_read_item(fp, &datum, &key))
goto err;
/*
* For type rules we have to make certain there aren't any
* conflicting rules by searching the te_avtab and the
* cond_te_avtab.
*/
if (datum.specified & AVTAB_TYPE) {
if (avtab_search(&p->te_avtab, &key, AVTAB_TYPE)) {
printk("security: type rule already exists outside of a conditional.");
goto err;
}
/*
* If we are reading the false list other will be a pointer to
* the true list. We can have duplicate entries if there is only
* 1 other entry and it is in our true list.
*
* If we are reading the true list (other == NULL) there shouldn't
* be any other entries.
*/
if (other) {
node_ptr = avtab_search_node(&p->te_cond_avtab, &key, AVTAB_TYPE);
if (node_ptr) {
if (avtab_search_node_next(node_ptr, AVTAB_TYPE)) {
printk("security: too many conflicting type rules.");
goto err;
}
found = 0;
for (cur = other; cur != NULL; cur = cur->next) {
if (cur->node == node_ptr) {
found = 1;
break;
}
}
if (!found) {
printk("security: conflicting type rules.");
goto err;
}
}
} else {
if (avtab_search(&p->te_cond_avtab, &key, AVTAB_TYPE)) {
printk("security: conflicting type rules when adding type rule for true.");
goto err;
}
}
}
node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, &key, &datum);
if (!node_ptr) {
printk("security: could not insert rule.");
goto err;
}
list = kmalloc(sizeof(struct cond_av_list), GFP_KERNEL);
if (!list)
goto err;
memset(list, 0, sizeof(struct cond_av_list));
list->node = node_ptr;
if (i == 0)
*ret_list = list;
else
last->next = list;
last = list;
}
return 0;
err:
cond_av_list_destroy(*ret_list);
*ret_list = NULL;
return -1;
}
static int expr_isvalid(struct policydb *p, struct cond_expr *expr)
{
if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
printk("security: conditional expressions uses unknown operator.\n");
return 0;
}
if (expr->bool > p->p_bools.nprim) {
printk("security: conditional expressions uses unknown bool.\n");
return 0;
}
return 1;
}
static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
{
u32 buf[2], len, i;
int rc;
struct cond_expr *expr = NULL, *last = NULL;
rc = next_entry(buf, fp, sizeof(u32));
if (rc < 0)
return -1;
node->cur_state = le32_to_cpu(buf[0]);
len = 0;
rc = next_entry(buf, fp, sizeof(u32));
if (rc < 0)
return -1;
/* expr */
len = le32_to_cpu(buf[0]);
for (i = 0; i < len; i++ ) {
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc < 0)
goto err;
expr = kmalloc(sizeof(struct cond_expr), GFP_KERNEL);
if (!expr) {
goto err;
}
memset(expr, 0, sizeof(struct cond_expr));
expr->expr_type = le32_to_cpu(buf[0]);
expr->bool = le32_to_cpu(buf[1]);
if (!expr_isvalid(p, expr)) {
kfree(expr);
goto err;
}
if (i == 0) {
node->expr = expr;
} else {
last->next = expr;
}
last = expr;
}
if (cond_read_av_list(p, fp, &node->true_list, NULL) != 0)
goto err;
if (cond_read_av_list(p, fp, &node->false_list, node->true_list) != 0)
goto err;
return 0;
err:
cond_node_destroy(node);
return -1;
}
int cond_read_list(struct policydb *p, void *fp)
{
struct cond_node *node, *last = NULL;
u32 buf[1], i, len;
int rc;
rc = next_entry(buf, fp, sizeof buf);
if (rc < 0)
return -1;
len = le32_to_cpu(buf[0]);
for (i = 0; i < len; i++) {
node = kmalloc(sizeof(struct cond_node), GFP_KERNEL);
if (!node)
goto err;
memset(node, 0, sizeof(struct cond_node));
if (cond_read_node(p, node, fp) != 0)
goto err;
if (i == 0) {
p->cond_list = node;
} else {
last->next = node;
}
last = node;
}
return 0;
err:
cond_list_destroy(p->cond_list);
return -1;
}
/* Determine whether additional permissions are granted by the conditional
* av table, and if so, add them to the result
*/
void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd)
{
struct avtab_node *node;
if(!ctab || !key || !avd)
return;
for(node = avtab_search_node(ctab, key, AVTAB_AV); node != NULL;
node = avtab_search_node_next(node, AVTAB_AV)) {
if ( (__u32) (AVTAB_ALLOWED|AVTAB_ENABLED) ==
(node->datum.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
avd->allowed |= avtab_allowed(&node->datum);
if ( (__u32) (AVTAB_AUDITDENY|AVTAB_ENABLED) ==
(node->datum.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED)))
/* Since a '0' in an auditdeny mask represents a
* permission we do NOT want to audit (dontaudit), we use
* the '&' operand to ensure that all '0's in the mask
* are retained (much unlike the allow and auditallow cases).
*/
avd->auditdeny &= avtab_auditdeny(&node->datum);
if ( (__u32) (AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
(node->datum.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
avd->auditallow |= avtab_auditallow(&node->datum);
}
return;
}
