1/* Authors: Joshua Brindle <jbrindle@tresys.com>
2 *
3 * Assertion checker for avtab entries, taken from
4 * checkpolicy.c by Stephen Smalley <sds@tycho.nsa.gov>
5 *
6 * Copyright (C) 2005 Tresys Technology, LLC
7 *
8 *  This library is free software; you can redistribute it and/or
9 *  modify it under the terms of the GNU Lesser General Public
10 *  License as published by the Free Software Foundation; either
11 *  version 2.1 of the License, or (at your option) any later version.
12 *
13 *  This library is distributed in the hope that it will be useful,
14 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 *  Lesser General Public License for more details.
17 *
18 *  You should have received a copy of the GNU Lesser General Public
19 *  License along with this library; if not, write to the Free Software
20 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
21 */
22
23#include <sepol/policydb/avtab.h>
24#include <sepol/policydb/policydb.h>
25#include <sepol/policydb/expand.h>
26#include <sepol/policydb/util.h>
27
28#include "debug.h"
29
30static int check_assertion_helper(sepol_handle_t * handle,
31				  policydb_t * p,
32				  avtab_t * te_avtab, avtab_t * te_cond_avtab,
33				  unsigned int stype, unsigned int ttype,
34				  avrule_t * avrule)
35{
36	avtab_key_t avkey;
37	avtab_ptr_t node;
38	class_perm_node_t *curperm;
39
40	for (curperm = avrule->perms; curperm != NULL; curperm = curperm->next) {
41		avkey.source_type = stype + 1;
42		avkey.target_type = ttype + 1;
43		avkey.target_class = curperm->class;
44		avkey.specified = AVTAB_ALLOWED;
45		for (node = avtab_search_node(te_avtab, &avkey);
46		     node != NULL;
47		     node = avtab_search_node_next(node, avkey.specified)) {
48			if (node->datum.data & curperm->data)
49				goto err;
50		}
51		for (node = avtab_search_node(te_cond_avtab, &avkey);
52		     node != NULL;
53		     node = avtab_search_node_next(node, avkey.specified)) {
54			if (node->datum.data & curperm->data)
55				goto err;
56		}
57	}
58
59	return 0;
60
61      err:
62	if (avrule->source_filename) {
63		ERR(handle, "neverallow on line %lu of %s (or line %lu of policy.conf) violated by allow %s %s:%s {%s };",
64		    avrule->source_line, avrule->source_filename, avrule->line,
65		    p->p_type_val_to_name[stype],
66		    p->p_type_val_to_name[ttype],
67		    p->p_class_val_to_name[curperm->class - 1],
68		    sepol_av_to_string(p, curperm->class,
69				       node->datum.data & curperm->data));
70	} else if (avrule->line) {
71		ERR(handle, "neverallow on line %lu violated by allow %s %s:%s {%s };",
72		    avrule->line, p->p_type_val_to_name[stype],
73		    p->p_type_val_to_name[ttype],
74		    p->p_class_val_to_name[curperm->class - 1],
75		    sepol_av_to_string(p, curperm->class,
76				       node->datum.data & curperm->data));
77	} else {
78		ERR(handle, "neverallow violated by allow %s %s:%s {%s };",
79		    p->p_type_val_to_name[stype],
80		    p->p_type_val_to_name[ttype],
81		    p->p_class_val_to_name[curperm->class - 1],
82		    sepol_av_to_string(p, curperm->class,
83				       node->datum.data & curperm->data));
84	}
85	return -1;
86}
87
88int check_assertions(sepol_handle_t * handle, policydb_t * p,
89		     avrule_t * avrules)
90{
91	avrule_t *a;
92	avtab_t te_avtab, te_cond_avtab;
93	ebitmap_node_t *snode, *tnode;
94	unsigned int i, j;
95	int rc;
96
97	if (!avrules) {
98		/* Since assertions are stored in avrules, if it is NULL
99		   there won't be any to check. This also prevents an invalid
100		   free if the avtabs are never initialized */
101		return 0;
102	}
103
104	if (avrules) {
105		if (avtab_init(&te_avtab))
106			goto oom;
107		if (avtab_init(&te_cond_avtab)) {
108			avtab_destroy(&te_avtab);
109			goto oom;
110		}
111		if (expand_avtab(p, &p->te_avtab, &te_avtab) ||
112		    expand_avtab(p, &p->te_cond_avtab, &te_cond_avtab)) {
113			avtab_destroy(&te_avtab);
114			avtab_destroy(&te_cond_avtab);
115			goto oom;
116		}
117	}
118
119	for (a = avrules; a != NULL; a = a->next) {
120		ebitmap_t *stypes = &a->stypes.types;
121		ebitmap_t *ttypes = &a->ttypes.types;
122
123		if (!(a->specified & AVRULE_NEVERALLOW))
124			continue;
125
126		ebitmap_for_each_bit(stypes, snode, i) {
127			if (!ebitmap_node_get_bit(snode, i))
128				continue;
129			if (a->flags & RULE_SELF) {
130				if (check_assertion_helper
131				    (handle, p, &te_avtab, &te_cond_avtab, i, i,
132				     a)) {
133					rc = -1;
134					goto out;
135				}
136			}
137			ebitmap_for_each_bit(ttypes, tnode, j) {
138				if (!ebitmap_node_get_bit(tnode, j))
139					continue;
140				if (check_assertion_helper
141				    (handle, p, &te_avtab, &te_cond_avtab, i, j,
142				     a)) {
143					rc = -1;
144					goto out;
145				}
146			}
147		}
148	}
149
150	rc = 0;
151out:
152	avtab_destroy(&te_avtab);
153	avtab_destroy(&te_cond_avtab);
154	return rc;
155
156      oom:
157	ERR(handle, "Out of memory - unable to check neverallows");
158	return -1;
159}
160