1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor functions for unpacking policy loaded
6 * from userspace.
7 *
8 * Copyright (C) 1998-2008 Novell/SUSE
9 * Copyright 2009-2022 Canonical Ltd.
10 *
11 * Code to provide backwards compatibility with older policy versions,
12 * by converting/mapping older policy formats into the newer internal
13 * formats.
14 */
15
16#include <linux/ctype.h>
17#include <linux/errno.h>
18
19#include "include/lib.h"
20#include "include/policy_unpack.h"
21#include "include/policy_compat.h"
22
23/* remap old accept table embedded permissions to separate permission table */
24static u32 dfa_map_xindex(u16 mask)
25{
26	u16 old_index = (mask >> 10) & 0xf;
27	u32 index = 0;
28
29	if (mask & 0x100)
30		index |= AA_X_UNSAFE;
31	if (mask & 0x200)
32		index |= AA_X_INHERIT;
33	if (mask & 0x80)
34		index |= AA_X_UNCONFINED;
35
36	if (old_index == 1) {
37		index |= AA_X_UNCONFINED;
38	} else if (old_index == 2) {
39		index |= AA_X_NAME;
40	} else if (old_index == 3) {
41		index |= AA_X_NAME | AA_X_CHILD;
42	} else if (old_index) {
43		index |= AA_X_TABLE;
44		index |= old_index - 4;
45	}
46
47	return index;
48}
49
50/*
51 * map old dfa inline permissions to new format
52 */
53#define dfa_user_allow(dfa, state) (((ACCEPT_TABLE(dfa)[state]) & 0x7f) | \
54				    ((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
55#define dfa_user_xbits(dfa, state) (((ACCEPT_TABLE(dfa)[state]) >> 7) & 0x7f)
56#define dfa_user_audit(dfa, state) ((ACCEPT_TABLE2(dfa)[state]) & 0x7f)
57#define dfa_user_quiet(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 7) & 0x7f)
58#define dfa_user_xindex(dfa, state) \
59	(dfa_map_xindex(ACCEPT_TABLE(dfa)[state] & 0x3fff))
60
61#define dfa_other_allow(dfa, state) ((((ACCEPT_TABLE(dfa)[state]) >> 14) & \
62				      0x7f) |				\
63				     ((ACCEPT_TABLE(dfa)[state]) & 0x80000000))
64#define dfa_other_xbits(dfa, state) \
65	((((ACCEPT_TABLE(dfa)[state]) >> 7) >> 14) & 0x7f)
66#define dfa_other_audit(dfa, state) (((ACCEPT_TABLE2(dfa)[state]) >> 14) & 0x7f)
67#define dfa_other_quiet(dfa, state) \
68	((((ACCEPT_TABLE2(dfa)[state]) >> 7) >> 14) & 0x7f)
69#define dfa_other_xindex(dfa, state) \
70	dfa_map_xindex((ACCEPT_TABLE(dfa)[state] >> 14) & 0x3fff)
71
72/**
73 * map_old_perms - map old file perms layout to the new layout
74 * @old: permission set in old mapping
75 *
76 * Returns: new permission mapping
77 */
78static u32 map_old_perms(u32 old)
79{
80	u32 new = old & 0xf;
81
82	if (old & MAY_READ)
83		new |= AA_MAY_GETATTR | AA_MAY_OPEN;
84	if (old & MAY_WRITE)
85		new |= AA_MAY_SETATTR | AA_MAY_CREATE | AA_MAY_DELETE |
86		       AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_OPEN;
87	if (old & 0x10)
88		new |= AA_MAY_LINK;
89	/* the old mapping lock and link_subset flags where overlaid
90	 * and use was determined by part of a pair that they were in
91	 */
92	if (old & 0x20)
93		new |= AA_MAY_LOCK | AA_LINK_SUBSET;
94	if (old & 0x40)	/* AA_EXEC_MMAP */
95		new |= AA_EXEC_MMAP;
96
97	return new;
98}
99
100static void compute_fperms_allow(struct aa_perms *perms, struct aa_dfa *dfa,
101				 aa_state_t state)
102{
103	perms->allow |= AA_MAY_GETATTR;
104
105	/* change_profile wasn't determined by ownership in old mapping */
106	if (ACCEPT_TABLE(dfa)[state] & 0x80000000)
107		perms->allow |= AA_MAY_CHANGE_PROFILE;
108	if (ACCEPT_TABLE(dfa)[state] & 0x40000000)
109		perms->allow |= AA_MAY_ONEXEC;
110}
111
112static struct aa_perms compute_fperms_user(struct aa_dfa *dfa,
113					   aa_state_t state)
114{
115	struct aa_perms perms = { };
116
117	perms.allow = map_old_perms(dfa_user_allow(dfa, state));
118	perms.audit = map_old_perms(dfa_user_audit(dfa, state));
119	perms.quiet = map_old_perms(dfa_user_quiet(dfa, state));
120	perms.xindex = dfa_user_xindex(dfa, state);
121
122	compute_fperms_allow(&perms, dfa, state);
123
124	return perms;
125}
126
127static struct aa_perms compute_fperms_other(struct aa_dfa *dfa,
128					    aa_state_t state)
129{
130	struct aa_perms perms = { };
131
132	perms.allow = map_old_perms(dfa_other_allow(dfa, state));
133	perms.audit = map_old_perms(dfa_other_audit(dfa, state));
134	perms.quiet = map_old_perms(dfa_other_quiet(dfa, state));
135	perms.xindex = dfa_other_xindex(dfa, state);
136
137	compute_fperms_allow(&perms, dfa, state);
138
139	return perms;
140}
141
142/**
143 * compute_fperms - convert dfa compressed perms to internal perms and store
144 *		    them so they can be retrieved later.
145 * @dfa: a dfa using fperms to remap to internal permissions
146 * @size: Returns the permission table size
147 *
148 * Returns: remapped perm table
149 */
150static struct aa_perms *compute_fperms(struct aa_dfa *dfa,
151				       u32 *size)
152{
153	aa_state_t state;
154	unsigned int state_count;
155	struct aa_perms *table;
156
157	AA_BUG(!dfa);
158
159	state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
160	/* DFAs are restricted from having a state_count of less than 2 */
161	table = kvcalloc(state_count * 2, sizeof(struct aa_perms), GFP_KERNEL);
162	if (!table)
163		return NULL;
164	*size = state_count * 2;
165
166	for (state = 0; state < state_count; state++) {
167		table[state * 2] = compute_fperms_user(dfa, state);
168		table[state * 2 + 1] = compute_fperms_other(dfa, state);
169	}
170
171	return table;
172}
173
174static struct aa_perms *compute_xmatch_perms(struct aa_dfa *xmatch,
175				      u32 *size)
176{
177	struct aa_perms *perms;
178	int state;
179	int state_count;
180
181	AA_BUG(!xmatch);
182
183	state_count = xmatch->tables[YYTD_ID_BASE]->td_lolen;
184	/* DFAs are restricted from having a state_count of less than 2 */
185	perms = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL);
186	if (!perms)
187		return NULL;
188	*size = state_count;
189
190	/* zero init so skip the trap state (state == 0) */
191	for (state = 1; state < state_count; state++)
192		perms[state].allow = dfa_user_allow(xmatch, state);
193
194	return perms;
195}
196
197static u32 map_other(u32 x)
198{
199	return ((x & 0x3) << 8) |	/* SETATTR/GETATTR */
200		((x & 0x1c) << 18) |	/* ACCEPT/BIND/LISTEN */
201		((x & 0x60) << 19);	/* SETOPT/GETOPT */
202}
203
204static u32 map_xbits(u32 x)
205{
206	return ((x & 0x1) << 7) |
207		((x & 0x7e) << 9);
208}
209
210static struct aa_perms compute_perms_entry(struct aa_dfa *dfa,
211					   aa_state_t state,
212					   u32 version)
213{
214	struct aa_perms perms = { };
215
216	perms.allow = dfa_user_allow(dfa, state);
217	perms.audit = dfa_user_audit(dfa, state);
218	perms.quiet = dfa_user_quiet(dfa, state);
219
220	/*
221	 * This mapping is convulated due to history.
222	 * v1-v4: only file perms, which are handled by compute_fperms
223	 * v5: added policydb which dropped user conditional to gain new
224	 *     perm bits, but had to map around the xbits because the
225	 *     userspace compiler was still munging them.
226	 * v9: adds using the xbits in policydb because the compiler now
227	 *     supports treating policydb permission bits different.
228	 *     Unfortunately there is no way to force auditing on the
229	 *     perms represented by the xbits
230	 */
231	perms.allow |= map_other(dfa_other_allow(dfa, state));
232	if (VERSION_LE(version, v8))
233		perms.allow |= AA_MAY_LOCK;
234	else
235		perms.allow |= map_xbits(dfa_user_xbits(dfa, state));
236
237	/*
238	 * for v5-v9 perm mapping in the policydb, the other set is used
239	 * to extend the general perm set
240	 */
241	perms.audit |= map_other(dfa_other_audit(dfa, state));
242	perms.quiet |= map_other(dfa_other_quiet(dfa, state));
243	if (VERSION_GT(version, v8))
244		perms.quiet |= map_xbits(dfa_other_xbits(dfa, state));
245
246	return perms;
247}
248
249static struct aa_perms *compute_perms(struct aa_dfa *dfa, u32 version,
250				      u32 *size)
251{
252	unsigned int state;
253	unsigned int state_count;
254	struct aa_perms *table;
255
256	AA_BUG(!dfa);
257
258	state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
259	/* DFAs are restricted from having a state_count of less than 2 */
260	table = kvcalloc(state_count, sizeof(struct aa_perms), GFP_KERNEL);
261	if (!table)
262		return NULL;
263	*size = state_count;
264
265	/* zero init so skip the trap state (state == 0) */
266	for (state = 1; state < state_count; state++)
267		table[state] = compute_perms_entry(dfa, state, version);
268
269	return table;
270}
271
272/**
273 * remap_dfa_accept - remap old dfa accept table to be an index
274 * @dfa: dfa to do the remapping on
275 * @factor: scaling factor for the index conversion.
276 *
277 * Used in conjunction with compute_Xperms, it converts old style perms
278 * that are encoded in the dfa accept tables to the new style where
279 * there is a permission table and the accept table is an index into
280 * the permission table.
281 */
282static void remap_dfa_accept(struct aa_dfa *dfa, unsigned int factor)
283{
284	unsigned int state;
285	unsigned int state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
286
287	AA_BUG(!dfa);
288
289	for (state = 0; state < state_count; state++)
290		ACCEPT_TABLE(dfa)[state] = state * factor;
291	kvfree(dfa->tables[YYTD_ID_ACCEPT2]);
292	dfa->tables[YYTD_ID_ACCEPT2] = NULL;
293}
294
295/* TODO: merge different dfa mappings into single map_policy fn */
296int aa_compat_map_xmatch(struct aa_policydb *policy)
297{
298	policy->perms = compute_xmatch_perms(policy->dfa, &policy->size);
299	if (!policy->perms)
300		return -ENOMEM;
301
302	remap_dfa_accept(policy->dfa, 1);
303
304	return 0;
305}
306
307int aa_compat_map_policy(struct aa_policydb *policy, u32 version)
308{
309	policy->perms = compute_perms(policy->dfa, version, &policy->size);
310	if (!policy->perms)
311		return -ENOMEM;
312
313	remap_dfa_accept(policy->dfa, 1);
314
315	return 0;
316}
317
318int aa_compat_map_file(struct aa_policydb *policy)
319{
320	policy->perms = compute_fperms(policy->dfa, &policy->size);
321	if (!policy->perms)
322		return -ENOMEM;
323
324	remap_dfa_accept(policy->dfa, 2);
325
326	return 0;
327}
328