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
map_signal_num(int sig)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 */
audit_signal_mask(u32 mask)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_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 */
audit_signal_cb(struct audit_buffer * ab,void * va)52 static 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
profile_signal_perm(const struct cred * cred,struct aa_profile * profile,struct aa_label * peer,u32 request,struct apparmor_audit_data * ad)78 static 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
aa_may_signal(const struct cred * subj_cred,struct aa_label * sender,const struct cred * target_cred,struct aa_label * target,int sig)103 int 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