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1 /*
2 * AppArmor security module
3 *
4 * This file contains AppArmor capability mediation functions
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 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/capability.h>
16 #include <linux/errno.h>
17 #include <linux/gfp.h>
18 #include <linux/security.h>
19
20 #include "include/apparmor.h"
21 #include "include/capability.h"
22 #include "include/context.h"
23 #include "include/policy.h"
24 #include "include/audit.h"
25
26 /*
27 * Table of capability names: we generate it from capabilities.h.
28 */
29 #include "capability_names.h"
30
31 struct aa_sfs_entry aa_sfs_entry_caps[] = {
32 AA_SFS_FILE_STRING("mask", AA_SFS_CAPS_MASK),
33 { }
34 };
35
36 struct audit_cache {
37 struct aa_profile *profile;
38 kernel_cap_t caps;
39 };
40
41 static DEFINE_PER_CPU(struct audit_cache, audit_cache);
42
43 /**
44 * audit_cb - call back for capability components of audit struct
45 * @ab - audit buffer (NOT NULL)
46 * @va - audit struct to audit data from (NOT NULL)
47 */
48 static void audit_cb(struct audit_buffer *ab, void *va)
49 {
50 struct common_audit_data *sa = va;
51
52 audit_log_format(ab, " capname=");
53 audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
54 }
55
56 /**
57 * audit_caps - audit a capability
58 * @sa: audit data
59 * @profile: profile being tested for confinement (NOT NULL)
60 * @cap: capability tested
61 * @error: error code returned by test
62 *
63 * Do auditing of capability and handle, audit/complain/kill modes switching
64 * and duplicate message elimination.
65 *
66 * Returns: 0 or sa->error on success, error code on failure
67 */
68 static int audit_caps(struct common_audit_data *sa, struct aa_profile *profile,
69 int cap, int error)
70 {
71 struct audit_cache *ent;
72 int type = AUDIT_APPARMOR_AUTO;
73
74 aad(sa)->error = error;
75
76 if (likely(!error)) {
77 /* test if auditing is being forced */
78 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
79 !cap_raised(profile->caps.audit, cap)))
80 return 0;
81 type = AUDIT_APPARMOR_AUDIT;
82 } else if (KILL_MODE(profile) ||
83 cap_raised(profile->caps.kill, cap)) {
84 type = AUDIT_APPARMOR_KILL;
85 } else if (cap_raised(profile->caps.quiet, cap) &&
86 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
87 AUDIT_MODE(profile) != AUDIT_ALL) {
88 /* quiet auditing */
89 return error;
90 }
91
92 /* Do simple duplicate message elimination */
93 ent = &get_cpu_var(audit_cache);
94 if (profile == ent->profile && cap_raised(ent->caps, cap)) {
95 put_cpu_var(audit_cache);
96 if (COMPLAIN_MODE(profile))
97 return complain_error(error);
98 return error;
99 } else {
100 aa_put_profile(ent->profile);
101 ent->profile = aa_get_profile(profile);
102 cap_raise(ent->caps, cap);
103 }
104 put_cpu_var(audit_cache);
105
106 return aa_audit(type, profile, sa, audit_cb);
107 }
108
109 /**
110 * profile_capable - test if profile allows use of capability @cap
111 * @profile: profile being enforced (NOT NULL, NOT unconfined)
112 * @cap: capability to test if allowed
113 * @audit: whether an audit record should be generated
114 * @sa: audit data (MAY BE NULL indicating no auditing)
115 *
116 * Returns: 0 if allowed else -EPERM
117 */
118 static int profile_capable(struct aa_profile *profile, int cap, int audit,
119 struct common_audit_data *sa)
120 {
121 int error;
122
123 if (cap_raised(profile->caps.allow, cap) &&
124 !cap_raised(profile->caps.denied, cap))
125 error = 0;
126 else
127 error = -EPERM;
128
129 if (audit == SECURITY_CAP_NOAUDIT) {
130 if (!COMPLAIN_MODE(profile))
131 return error;
132 /* audit the cap request in complain mode but note that it
133 * should be optional.
134 */
135 aad(sa)->info = "optional: no audit";
136 }
137
138 return audit_caps(sa, profile, cap, error);
139 }
140
141 /**
142 * aa_capable - test permission to use capability
143 * @label: label being tested for capability (NOT NULL)
144 * @cap: capability to be tested
145 * @audit: whether an audit record should be generated
146 *
147 * Look up capability in profile capability set.
148 *
149 * Returns: 0 on success, or else an error code.
150 */
151 int aa_capable(struct aa_label *label, int cap, int audit)
152 {
153 struct aa_profile *profile;
154 int error = 0;
155 DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_CAP, OP_CAPABLE);
156
157 sa.u.cap = cap;
158 error = fn_for_each_confined(label, profile,
159 profile_capable(profile, cap, audit, &sa));
160
161 return error;
162 }