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#include <linux/ptrace.h>
13
14#include "include/audit.h"
15#include "include/capability.h"
16#include "include/cred.h"
17#include "include/policy.h"
18#include "include/ipc.h"
19#include "include/sig_names.h"
20
21/**
22 * audit_ptrace_mask - convert mask to permission string
23 * @mask: permission mask to convert
24 *
25 * Returns: pointer to static string
26 */
27static const char *audit_ptrace_mask(u32 mask)
28{
29	switch (mask) {
30	case MAY_READ:
31		return "read";
32	case MAY_WRITE:
33		return "trace";
34	case AA_MAY_BE_READ:
35		return "readby";
36	case AA_MAY_BE_TRACED:
37		return "tracedby";
38	}
39	return "";
40}
41
42/* call back to audit ptrace fields */
43static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
44{
45	struct common_audit_data *sa = va;
46
47	if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
48		audit_log_format(ab, " requested_mask=\"%s\"",
49				 audit_ptrace_mask(aad(sa)->request));
50
51		if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
52			audit_log_format(ab, " denied_mask=\"%s\"",
53					 audit_ptrace_mask(aad(sa)->denied));
54		}
55	}
56	audit_log_format(ab, " peer=");
57	aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
58			FLAGS_NONE, GFP_ATOMIC);
59}
60
61/* assumes check for PROFILE_MEDIATES is already done */
62/* TODO: conditionals */
63static int profile_ptrace_perm(struct aa_profile *profile,
64			     struct aa_label *peer, u32 request,
65			     struct common_audit_data *sa)
66{
67	struct aa_perms perms = { };
68
69	aad(sa)->peer = peer;
70	aa_profile_match_label(profile, peer, AA_CLASS_PTRACE, request,
71			       &perms);
72	aa_apply_modes_to_perms(profile, &perms);
73	return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
74}
75
76static int profile_tracee_perm(struct aa_profile *tracee,
77			       struct aa_label *tracer, u32 request,
78			       struct common_audit_data *sa)
79{
80	if (profile_unconfined(tracee) || unconfined(tracer) ||
81	    !PROFILE_MEDIATES(tracee, AA_CLASS_PTRACE))
82		return 0;
83
84	return profile_ptrace_perm(tracee, tracer, request, sa);
85}
86
87static int profile_tracer_perm(struct aa_profile *tracer,
88			       struct aa_label *tracee, u32 request,
89			       struct common_audit_data *sa)
90{
91	if (profile_unconfined(tracer))
92		return 0;
93
94	if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
95		return profile_ptrace_perm(tracer, tracee, request, sa);
96
97	/* profile uses the old style capability check for ptrace */
98	if (&tracer->label == tracee)
99		return 0;
100
101	aad(sa)->label = &tracer->label;
102	aad(sa)->peer = tracee;
103	aad(sa)->request = 0;
104	aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE,
105				    CAP_OPT_NONE);
106
107	return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
108}
109
110/**
111 * aa_may_ptrace - test if tracer task can trace the tracee
112 * @tracer: label of the task doing the tracing  (NOT NULL)
113 * @tracee: task label to be traced
114 * @request: permission request
115 *
116 * Returns: %0 else error code if permission denied or error
117 */
118int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
119		  u32 request)
120{
121	struct aa_profile *profile;
122	u32 xrequest = request << PTRACE_PERM_SHIFT;
123	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
124
125	return xcheck_labels(tracer, tracee, profile,
126			profile_tracer_perm(profile, tracee, request, &sa),
127			profile_tracee_perm(profile, tracer, xrequest, &sa));
128}
129
130
131static inline int map_signal_num(int sig)
132{
133	if (sig > SIGRTMAX)
134		return SIGUNKNOWN;
135	else if (sig >= SIGRTMIN)
136		return sig - SIGRTMIN + SIGRT_BASE;
137	else if (sig < MAXMAPPED_SIG)
138		return sig_map[sig];
139	return SIGUNKNOWN;
140}
141
142/**
143 * audit_signal_mask - convert mask to permission string
144 * @mask: permission mask to convert
145 *
146 * Returns: pointer to static string
147 */
148static const char *audit_signal_mask(u32 mask)
149{
150	if (mask & MAY_READ)
151		return "receive";
152	if (mask & MAY_WRITE)
153		return "send";
154	return "";
155}
156
157/**
158 * audit_cb - call back for signal specific audit fields
159 * @ab: audit_buffer  (NOT NULL)
160 * @va: audit struct to audit values of  (NOT NULL)
161 */
162static void audit_signal_cb(struct audit_buffer *ab, void *va)
163{
164	struct common_audit_data *sa = va;
165
166	if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
167		audit_log_format(ab, " requested_mask=\"%s\"",
168				 audit_signal_mask(aad(sa)->request));
169		if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
170			audit_log_format(ab, " denied_mask=\"%s\"",
171					 audit_signal_mask(aad(sa)->denied));
172		}
173	}
174	if (aad(sa)->signal == SIGUNKNOWN)
175		audit_log_format(ab, "signal=unknown(%d)",
176				 aad(sa)->unmappedsig);
177	else if (aad(sa)->signal < MAXMAPPED_SIGNAME)
178		audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
179	else
180		audit_log_format(ab, " signal=rtmin+%d",
181				 aad(sa)->signal - SIGRT_BASE);
182	audit_log_format(ab, " peer=");
183	aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
184			FLAGS_NONE, GFP_ATOMIC);
185}
186
187static int profile_signal_perm(struct aa_profile *profile,
188			       struct aa_label *peer, u32 request,
189			       struct common_audit_data *sa)
190{
191	struct aa_perms perms;
192	unsigned int state;
193
194	if (profile_unconfined(profile) ||
195	    !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
196		return 0;
197
198	aad(sa)->peer = peer;
199	/* TODO: secondary cache check <profile, profile, perm> */
200	state = aa_dfa_next(profile->policy.dfa,
201			    profile->policy.start[AA_CLASS_SIGNAL],
202			    aad(sa)->signal);
203	aa_label_match(profile, peer, state, false, request, &perms);
204	aa_apply_modes_to_perms(profile, &perms);
205	return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
206}
207
208int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
209{
210	struct aa_profile *profile;
211	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
212
213	aad(&sa)->signal = map_signal_num(sig);
214	aad(&sa)->unmappedsig = sig;
215	return xcheck_labels(sender, target, profile,
216			profile_signal_perm(profile, target, MAY_WRITE, &sa),
217			profile_signal_perm(profile, sender, MAY_READ, &sa));
218}
219