1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor ipc mediation
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2017 Canonical Ltd.
9 */
10
11#include <linux/gfp.h>
12
13#include "include/audit.h"
14#include "include/capability.h"
15#include "include/cred.h"
16#include "include/policy.h"
17#include "include/ipc.h"
18#include "include/sig_names.h"
19
20
21static inline int map_signal_num(int sig)
22{
23	if (sig > SIGRTMAX)
24		return SIGUNKNOWN;
25	else if (sig >= SIGRTMIN)
26		return sig - SIGRTMIN + SIGRT_BASE;
27	else if (sig < MAXMAPPED_SIG)
28		return sig_map[sig];
29	return SIGUNKNOWN;
30}
31
32/**
33 * audit_signal_mask - convert mask to permission string
34 * @mask: permission mask to convert
35 *
36 * Returns: pointer to static string
37 */
38static const char *audit_signal_mask(u32 mask)
39{
40	if (mask & MAY_READ)
41		return "receive";
42	if (mask & MAY_WRITE)
43		return "send";
44	return "";
45}
46
47/**
48 * audit_signal_cb() - call back for signal specific audit fields
49 * @ab: audit_buffer  (NOT NULL)
50 * @va: audit struct to audit values of  (NOT NULL)
51 */
52static void audit_signal_cb(struct audit_buffer *ab, void *va)
53{
54	struct common_audit_data *sa = va;
55	struct apparmor_audit_data *ad = aad(sa);
56
57	if (ad->request & AA_SIGNAL_PERM_MASK) {
58		audit_log_format(ab, " requested_mask=\"%s\"",
59				 audit_signal_mask(ad->request));
60		if (ad->denied & AA_SIGNAL_PERM_MASK) {
61			audit_log_format(ab, " denied_mask=\"%s\"",
62					 audit_signal_mask(ad->denied));
63		}
64	}
65	if (ad->signal == SIGUNKNOWN)
66		audit_log_format(ab, "signal=unknown(%d)",
67				 ad->unmappedsig);
68	else if (ad->signal < MAXMAPPED_SIGNAME)
69		audit_log_format(ab, " signal=%s", sig_names[ad->signal]);
70	else
71		audit_log_format(ab, " signal=rtmin+%d",
72				 ad->signal - SIGRT_BASE);
73	audit_log_format(ab, " peer=");
74	aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
75			FLAGS_NONE, GFP_ATOMIC);
76}
77
78static int profile_signal_perm(const struct cred *cred,
79			       struct aa_profile *profile,
80			       struct aa_label *peer, u32 request,
81			       struct apparmor_audit_data *ad)
82{
83	struct aa_ruleset *rules = list_first_entry(&profile->rules,
84						    typeof(*rules), list);
85	struct aa_perms perms;
86	aa_state_t state;
87
88	if (profile_unconfined(profile) ||
89	    !ANY_RULE_MEDIATES(&profile->rules, AA_CLASS_SIGNAL))
90		return 0;
91
92	ad->subj_cred = cred;
93	ad->peer = peer;
94	/* TODO: secondary cache check <profile, profile, perm> */
95	state = aa_dfa_next(rules->policy->dfa,
96			    rules->policy->start[AA_CLASS_SIGNAL],
97			    ad->signal);
98	aa_label_match(profile, rules, peer, state, false, request, &perms);
99	aa_apply_modes_to_perms(profile, &perms);
100	return aa_check_perms(profile, &perms, request, ad, audit_signal_cb);
101}
102
103int aa_may_signal(const struct cred *subj_cred, struct aa_label *sender,
104		  const struct cred *target_cred, struct aa_label *target,
105		  int sig)
106{
107	struct aa_profile *profile;
108	DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_SIGNAL, OP_SIGNAL);
109
110	ad.signal = map_signal_num(sig);
111	ad.unmappedsig = sig;
112	return xcheck_labels(sender, target, profile,
113			     profile_signal_perm(subj_cred, profile, target,
114						 MAY_WRITE, &ad),
115			     profile_signal_perm(target_cred, profile, sender,
116						 MAY_READ, &ad));
117}
118