xref: /openbmc/linux/security/apparmor/ipc.c (revision f5c27da4)
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 
21 static 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  */
38 static 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_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  */
52 static void audit_signal_cb(struct audit_buffer *ab, void *va)
53 {
54 	struct common_audit_data *sa = va;
55 
56 	if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
57 		audit_log_format(ab, " requested_mask=\"%s\"",
58 				 audit_signal_mask(aad(sa)->request));
59 		if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
60 			audit_log_format(ab, " denied_mask=\"%s\"",
61 					 audit_signal_mask(aad(sa)->denied));
62 		}
63 	}
64 	if (aad(sa)->signal == SIGUNKNOWN)
65 		audit_log_format(ab, "signal=unknown(%d)",
66 				 aad(sa)->unmappedsig);
67 	else if (aad(sa)->signal < MAXMAPPED_SIGNAME)
68 		audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
69 	else
70 		audit_log_format(ab, " signal=rtmin+%d",
71 				 aad(sa)->signal - SIGRT_BASE);
72 	audit_log_format(ab, " peer=");
73 	aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
74 			FLAGS_NONE, GFP_ATOMIC);
75 }
76 
77 static int profile_signal_perm(struct aa_profile *profile,
78 			       struct aa_label *peer, u32 request,
79 			       struct common_audit_data *sa)
80 {
81 	struct aa_perms perms;
82 	unsigned int state;
83 
84 	if (profile_unconfined(profile) ||
85 	    !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
86 		return 0;
87 
88 	aad(sa)->peer = peer;
89 	/* TODO: secondary cache check <profile, profile, perm> */
90 	state = aa_dfa_next(profile->policy.dfa,
91 			    profile->policy.start[AA_CLASS_SIGNAL],
92 			    aad(sa)->signal);
93 	aa_label_match(profile, peer, state, false, request, &perms);
94 	aa_apply_modes_to_perms(profile, &perms);
95 	return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
96 }
97 
98 int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
99 {
100 	struct aa_profile *profile;
101 	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
102 
103 	aad(&sa)->signal = map_signal_num(sig);
104 	aad(&sa)->unmappedsig = sig;
105 	return xcheck_labels(sender, target, profile,
106 			profile_signal_perm(profile, target, MAY_WRITE, &sa),
107 			profile_signal_perm(profile, sender, MAY_READ, &sa));
108 }
109