xref: /openbmc/linux/security/apparmor/ipc.c (revision ddc141e5)
1 /*
2  * AppArmor security module
3  *
4  * This file contains AppArmor ipc mediation
5  *
6  * Copyright (C) 1998-2008 Novell/SUSE
7  * Copyright 2009-2017 Canonical Ltd.
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License as
11  * published by the Free Software Foundation, version 2 of the
12  * License.
13  */
14 
15 #include <linux/gfp.h>
16 #include <linux/ptrace.h>
17 
18 #include "include/audit.h"
19 #include "include/capability.h"
20 #include "include/context.h"
21 #include "include/policy.h"
22 #include "include/ipc.h"
23 #include "include/sig_names.h"
24 
25 /**
26  * audit_ptrace_mask - convert mask to permission string
27  * @buffer: buffer to write string to (NOT NULL)
28  * @mask: permission mask to convert
29  */
30 static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
31 {
32 	switch (mask) {
33 	case MAY_READ:
34 		audit_log_string(ab, "read");
35 		break;
36 	case MAY_WRITE:
37 		audit_log_string(ab, "trace");
38 		break;
39 	case AA_MAY_BE_READ:
40 		audit_log_string(ab, "readby");
41 		break;
42 	case AA_MAY_BE_TRACED:
43 		audit_log_string(ab, "tracedby");
44 		break;
45 	}
46 }
47 
48 /* call back to audit ptrace fields */
49 static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
50 {
51 	struct common_audit_data *sa = va;
52 
53 	if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
54 		audit_log_format(ab, " requested_mask=");
55 		audit_ptrace_mask(ab, aad(sa)->request);
56 
57 		if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
58 			audit_log_format(ab, " denied_mask=");
59 			audit_ptrace_mask(ab, aad(sa)->denied);
60 		}
61 	}
62 	audit_log_format(ab, " peer=");
63 	aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
64 			FLAGS_NONE, GFP_ATOMIC);
65 }
66 
67 /* assumes check for PROFILE_MEDIATES is already done */
68 /* TODO: conditionals */
69 static int profile_ptrace_perm(struct aa_profile *profile,
70 			     struct aa_label *peer, u32 request,
71 			     struct common_audit_data *sa)
72 {
73 	struct aa_perms perms = { };
74 
75 	aad(sa)->peer = peer;
76 	aa_profile_match_label(profile, peer, AA_CLASS_PTRACE, request,
77 			       &perms);
78 	aa_apply_modes_to_perms(profile, &perms);
79 	return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
80 }
81 
82 static int profile_tracee_perm(struct aa_profile *tracee,
83 			       struct aa_label *tracer, u32 request,
84 			       struct common_audit_data *sa)
85 {
86 	if (profile_unconfined(tracee) || unconfined(tracer) ||
87 	    !PROFILE_MEDIATES(tracee, AA_CLASS_PTRACE))
88 		return 0;
89 
90 	return profile_ptrace_perm(tracee, tracer, request, sa);
91 }
92 
93 static int profile_tracer_perm(struct aa_profile *tracer,
94 			       struct aa_label *tracee, u32 request,
95 			       struct common_audit_data *sa)
96 {
97 	if (profile_unconfined(tracer))
98 		return 0;
99 
100 	if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
101 		return profile_ptrace_perm(tracer, tracee, request, sa);
102 
103 	/* profile uses the old style capability check for ptrace */
104 	if (&tracer->label == tracee)
105 		return 0;
106 
107 	aad(sa)->label = &tracer->label;
108 	aad(sa)->peer = tracee;
109 	aad(sa)->request = 0;
110 	aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
111 
112 	return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
113 }
114 
115 /**
116  * aa_may_ptrace - test if tracer task can trace the tracee
117  * @tracer: label of the task doing the tracing  (NOT NULL)
118  * @tracee: task label to be traced
119  * @request: permission request
120  *
121  * Returns: %0 else error code if permission denied or error
122  */
123 int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
124 		  u32 request)
125 {
126 	struct aa_profile *profile;
127 	u32 xrequest = request << PTRACE_PERM_SHIFT;
128 	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
129 
130 	return xcheck_labels(tracer, tracee, profile,
131 			profile_tracer_perm(profile, tracee, request, &sa),
132 			profile_tracee_perm(profile, tracer, xrequest, &sa));
133 }
134 
135 
136 static inline int map_signal_num(int sig)
137 {
138 	if (sig > SIGRTMAX)
139 		return SIGUNKNOWN;
140 	else if (sig >= SIGRTMIN)
141 		return sig - SIGRTMIN + 128;	/* rt sigs mapped to 128 */
142 	else if (sig < MAXMAPPED_SIG)
143 		return sig_map[sig];
144 	return SIGUNKNOWN;
145 }
146 
147 /**
148  * audit_file_mask - convert mask to permission string
149  * @buffer: buffer to write string to (NOT NULL)
150  * @mask: permission mask to convert
151  */
152 static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
153 {
154 	if (mask & MAY_READ)
155 		audit_log_string(ab, "receive");
156 	if (mask & MAY_WRITE)
157 		audit_log_string(ab, "send");
158 }
159 
160 /**
161  * audit_cb - call back for signal specific audit fields
162  * @ab: audit_buffer  (NOT NULL)
163  * @va: audit struct to audit values of  (NOT NULL)
164  */
165 static void audit_signal_cb(struct audit_buffer *ab, void *va)
166 {
167 	struct common_audit_data *sa = va;
168 
169 	if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
170 		audit_log_format(ab, " requested_mask=");
171 		audit_signal_mask(ab, aad(sa)->request);
172 		if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
173 			audit_log_format(ab, " denied_mask=");
174 			audit_signal_mask(ab, aad(sa)->denied);
175 		}
176 	}
177 	if (aad(sa)->signal < MAXMAPPED_SIG)
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 - 128);
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 
187 /* TODO: update to handle compound name&name2, conditionals */
188 static void profile_match_signal(struct aa_profile *profile, const char *label,
189 				 int signal, struct aa_perms *perms)
190 {
191 	unsigned int state;
192 
193 	/* TODO: secondary cache check <profile, profile, perm> */
194 	state = aa_dfa_next(profile->policy.dfa,
195 			    profile->policy.start[AA_CLASS_SIGNAL],
196 			    signal);
197 	state = aa_dfa_match(profile->policy.dfa, state, label);
198 	aa_compute_perms(profile->policy.dfa, state, perms);
199 }
200 
201 static int profile_signal_perm(struct aa_profile *profile,
202 			       struct aa_profile *peer, u32 request,
203 			       struct common_audit_data *sa)
204 {
205 	struct aa_perms perms;
206 
207 	if (profile_unconfined(profile) ||
208 	    !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
209 		return 0;
210 
211 	aad(sa)->peer = &peer->label;
212 	profile_match_signal(profile, peer->base.hname, aad(sa)->signal,
213 			     &perms);
214 	aa_apply_modes_to_perms(profile, &perms);
215 	return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
216 }
217 
218 static int aa_signal_cross_perm(struct aa_profile *sender,
219 				struct aa_profile *target,
220 				struct common_audit_data *sa)
221 {
222 	return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),
223 		      profile_signal_perm(target, sender, MAY_READ, sa));
224 }
225 
226 int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
227 {
228 	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
229 
230 	aad(&sa)->signal = map_signal_num(sig);
231 	return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,
232 				      &sa);
233 }
234