507 lines
11 KiB
C
507 lines
11 KiB
C
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/* Authors: Karl MacMillan <kmacmillan@tresys.com>
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* Frank Mayer <mayerf@tresys.com>
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*
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* Copyright (C) 2003 - 2004 Tresys Technology, LLC
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2.
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*/
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include "security.h"
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#include "conditional.h"
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/*
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* cond_evaluate_expr evaluates a conditional expr
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* in reverse polish notation. It returns true (1), false (0),
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* or undefined (-1). Undefined occurs when the expression
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* exceeds the stack depth of COND_EXPR_MAXDEPTH.
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*/
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static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
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{
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struct cond_expr *cur;
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int s[COND_EXPR_MAXDEPTH];
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int sp = -1;
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for (cur = expr; cur; cur = cur->next) {
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switch (cur->expr_type) {
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case COND_BOOL:
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if (sp == (COND_EXPR_MAXDEPTH - 1))
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return -1;
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sp++;
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s[sp] = p->bool_val_to_struct[cur->bool - 1]->state;
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break;
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case COND_NOT:
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if (sp < 0)
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return -1;
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s[sp] = !s[sp];
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break;
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case COND_OR:
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if (sp < 1)
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return -1;
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sp--;
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s[sp] |= s[sp + 1];
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break;
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case COND_AND:
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if (sp < 1)
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return -1;
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sp--;
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s[sp] &= s[sp + 1];
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break;
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case COND_XOR:
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if (sp < 1)
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return -1;
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sp--;
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s[sp] ^= s[sp + 1];
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break;
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case COND_EQ:
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if (sp < 1)
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return -1;
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sp--;
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s[sp] = (s[sp] == s[sp + 1]);
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break;
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case COND_NEQ:
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if (sp < 1)
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return -1;
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sp--;
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s[sp] = (s[sp] != s[sp + 1]);
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break;
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default:
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return -1;
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}
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}
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return s[0];
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}
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/*
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* evaluate_cond_node evaluates the conditional stored in
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* a struct cond_node and if the result is different than the
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* current state of the node it sets the rules in the true/false
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* list appropriately. If the result of the expression is undefined
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* all of the rules are disabled for safety.
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*/
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int evaluate_cond_node(struct policydb *p, struct cond_node *node)
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{
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int new_state;
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struct cond_av_list *cur;
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new_state = cond_evaluate_expr(p, node->expr);
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if (new_state != node->cur_state) {
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node->cur_state = new_state;
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if (new_state == -1)
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printk(KERN_ERR "SELinux: expression result was undefined - disabling all rules.\n");
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/* turn the rules on or off */
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for (cur = node->true_list; cur; cur = cur->next) {
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if (new_state <= 0)
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cur->node->key.specified &= ~AVTAB_ENABLED;
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else
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cur->node->key.specified |= AVTAB_ENABLED;
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}
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for (cur = node->false_list; cur; cur = cur->next) {
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/* -1 or 1 */
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if (new_state)
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cur->node->key.specified &= ~AVTAB_ENABLED;
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else
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cur->node->key.specified |= AVTAB_ENABLED;
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}
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}
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return 0;
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}
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int cond_policydb_init(struct policydb *p)
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{
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p->bool_val_to_struct = NULL;
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p->cond_list = NULL;
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if (avtab_init(&p->te_cond_avtab))
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return -1;
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return 0;
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}
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static void cond_av_list_destroy(struct cond_av_list *list)
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{
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struct cond_av_list *cur, *next;
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for (cur = list; cur; cur = next) {
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next = cur->next;
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/* the avtab_ptr_t node is destroy by the avtab */
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kfree(cur);
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}
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}
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static void cond_node_destroy(struct cond_node *node)
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{
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struct cond_expr *cur_expr, *next_expr;
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for (cur_expr = node->expr; cur_expr; cur_expr = next_expr) {
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next_expr = cur_expr->next;
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kfree(cur_expr);
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}
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cond_av_list_destroy(node->true_list);
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cond_av_list_destroy(node->false_list);
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kfree(node);
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}
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static void cond_list_destroy(struct cond_node *list)
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{
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struct cond_node *next, *cur;
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if (list == NULL)
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return;
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for (cur = list; cur; cur = next) {
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next = cur->next;
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cond_node_destroy(cur);
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}
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}
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void cond_policydb_destroy(struct policydb *p)
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{
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kfree(p->bool_val_to_struct);
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avtab_destroy(&p->te_cond_avtab);
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cond_list_destroy(p->cond_list);
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}
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int cond_init_bool_indexes(struct policydb *p)
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{
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kfree(p->bool_val_to_struct);
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p->bool_val_to_struct = (struct cond_bool_datum **)
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kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum *), GFP_KERNEL);
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if (!p->bool_val_to_struct)
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return -1;
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return 0;
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}
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int cond_destroy_bool(void *key, void *datum, void *p)
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{
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kfree(key);
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kfree(datum);
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return 0;
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}
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int cond_index_bool(void *key, void *datum, void *datap)
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{
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struct policydb *p;
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struct cond_bool_datum *booldatum;
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booldatum = datum;
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p = datap;
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if (!booldatum->value || booldatum->value > p->p_bools.nprim)
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return -EINVAL;
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p->p_bool_val_to_name[booldatum->value - 1] = key;
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p->bool_val_to_struct[booldatum->value - 1] = booldatum;
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return 0;
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}
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static int bool_isvalid(struct cond_bool_datum *b)
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{
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if (!(b->state == 0 || b->state == 1))
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return 0;
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return 1;
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}
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int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp)
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{
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char *key = NULL;
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struct cond_bool_datum *booldatum;
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__le32 buf[3];
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u32 len;
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int rc;
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booldatum = kzalloc(sizeof(struct cond_bool_datum), GFP_KERNEL);
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if (!booldatum)
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return -1;
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rc = next_entry(buf, fp, sizeof buf);
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if (rc < 0)
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goto err;
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booldatum->value = le32_to_cpu(buf[0]);
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booldatum->state = le32_to_cpu(buf[1]);
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if (!bool_isvalid(booldatum))
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goto err;
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len = le32_to_cpu(buf[2]);
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key = kmalloc(len + 1, GFP_KERNEL);
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if (!key)
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goto err;
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rc = next_entry(key, fp, len);
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if (rc < 0)
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goto err;
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key[len] = '\0';
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if (hashtab_insert(h, key, booldatum))
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goto err;
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return 0;
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err:
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cond_destroy_bool(key, booldatum, NULL);
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return -1;
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}
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struct cond_insertf_data {
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struct policydb *p;
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struct cond_av_list *other;
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struct cond_av_list *head;
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struct cond_av_list *tail;
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};
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static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum *d, void *ptr)
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{
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struct cond_insertf_data *data = ptr;
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struct policydb *p = data->p;
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struct cond_av_list *other = data->other, *list, *cur;
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struct avtab_node *node_ptr;
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u8 found;
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/*
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* For type rules we have to make certain there aren't any
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* conflicting rules by searching the te_avtab and the
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* cond_te_avtab.
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*/
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if (k->specified & AVTAB_TYPE) {
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if (avtab_search(&p->te_avtab, k)) {
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printk(KERN_ERR "SELinux: type rule already exists outside of a conditional.\n");
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goto err;
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}
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/*
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* If we are reading the false list other will be a pointer to
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* the true list. We can have duplicate entries if there is only
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* 1 other entry and it is in our true list.
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*
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* If we are reading the true list (other == NULL) there shouldn't
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* be any other entries.
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*/
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if (other) {
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node_ptr = avtab_search_node(&p->te_cond_avtab, k);
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if (node_ptr) {
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if (avtab_search_node_next(node_ptr, k->specified)) {
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printk(KERN_ERR "SELinux: too many conflicting type rules.\n");
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goto err;
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}
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found = 0;
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for (cur = other; cur; cur = cur->next) {
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if (cur->node == node_ptr) {
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found = 1;
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break;
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}
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}
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if (!found) {
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printk(KERN_ERR "SELinux: conflicting type rules.\n");
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goto err;
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}
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}
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} else {
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if (avtab_search(&p->te_cond_avtab, k)) {
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printk(KERN_ERR "SELinux: conflicting type rules when adding type rule for true.\n");
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goto err;
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}
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}
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}
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node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d);
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if (!node_ptr) {
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printk(KERN_ERR "SELinux: could not insert rule.\n");
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goto err;
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}
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list = kzalloc(sizeof(struct cond_av_list), GFP_KERNEL);
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if (!list)
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goto err;
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list->node = node_ptr;
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if (!data->head)
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data->head = list;
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else
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data->tail->next = list;
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data->tail = list;
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return 0;
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err:
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cond_av_list_destroy(data->head);
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data->head = NULL;
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return -1;
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}
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static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list, struct cond_av_list *other)
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{
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int i, rc;
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__le32 buf[1];
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u32 len;
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struct cond_insertf_data data;
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*ret_list = NULL;
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len = 0;
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rc = next_entry(buf, fp, sizeof(u32));
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if (rc < 0)
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return -1;
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len = le32_to_cpu(buf[0]);
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if (len == 0)
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return 0;
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data.p = p;
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data.other = other;
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data.head = NULL;
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data.tail = NULL;
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for (i = 0; i < len; i++) {
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rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
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&data);
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if (rc)
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return rc;
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}
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*ret_list = data.head;
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return 0;
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}
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static int expr_isvalid(struct policydb *p, struct cond_expr *expr)
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{
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if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
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printk(KERN_ERR "SELinux: conditional expressions uses unknown operator.\n");
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return 0;
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}
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if (expr->bool > p->p_bools.nprim) {
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printk(KERN_ERR "SELinux: conditional expressions uses unknown bool.\n");
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return 0;
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}
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return 1;
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}
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static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
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{
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__le32 buf[2];
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u32 len, i;
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int rc;
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struct cond_expr *expr = NULL, *last = NULL;
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rc = next_entry(buf, fp, sizeof(u32));
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|
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 = kzalloc(sizeof(struct cond_expr), GFP_KERNEL);
|
||
|
|
if (!expr)
|
||
|
|
goto err;
|
||
|
|
|
||
|
|
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;
|
||
|
|
__le32 buf[1];
|
||
|
|
u32 i, len;
|
||
|
|
int rc;
|
||
|
|
|
||
|
|
rc = next_entry(buf, fp, sizeof buf);
|
||
|
|
if (rc < 0)
|
||
|
|
return -1;
|
||
|
|
|
||
|
|
len = le32_to_cpu(buf[0]);
|
||
|
|
|
||
|
|
rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel);
|
||
|
|
if (rc)
|
||
|
|
goto err;
|
||
|
|
|
||
|
|
for (i = 0; i < len; i++) {
|
||
|
|
node = kzalloc(sizeof(struct cond_node), GFP_KERNEL);
|
||
|
|
if (!node)
|
||
|
|
goto err;
|
||
|
|
|
||
|
|
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);
|
||
|
|
p->cond_list = NULL;
|
||
|
|
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); node;
|
||
|
|
node = avtab_search_node_next(node, key->specified)) {
|
||
|
|
if ((u16)(AVTAB_ALLOWED|AVTAB_ENABLED) ==
|
||
|
|
(node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
|
||
|
|
avd->allowed |= node->datum.data;
|
||
|
|
if ((u16)(AVTAB_AUDITDENY|AVTAB_ENABLED) ==
|
||
|
|
(node->key.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 &= node->datum.data;
|
||
|
|
if ((u16)(AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
|
||
|
|
(node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
|
||
|
|
avd->auditallow |= node->datum.data;
|
||
|
|
}
|
||
|
|
return;
|
||
|
|
}
|