1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AppArmor security module
4 *
5 * This file contains AppArmor capability mediation functions
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 */
10
11 #include <linux/capability.h>
12 #include <linux/errno.h>
13 #include <linux/gfp.h>
14 #include <linux/security.h>
15
16 #include "include/apparmor.h"
17 #include "include/capability.h"
18 #include "include/cred.h"
19 #include "include/policy.h"
20 #include "include/audit.h"
21
22 /*
23 * Table of capability names: we generate it from capabilities.h.
24 */
25 #include "capability_names.h"
26
27 struct aa_sfs_entry aa_sfs_entry_caps[] = {
28 AA_SFS_FILE_STRING("mask", AA_SFS_CAPS_MASK),
29 { }
30 };
31
32 struct audit_cache {
33 struct aa_profile *profile;
34 kernel_cap_t caps;
35 };
36
37 static DEFINE_PER_CPU(struct audit_cache, audit_cache);
38
39 /**
40 * audit_cb - call back for capability components of audit struct
41 * @ab: audit buffer (NOT NULL)
42 * @va: audit struct to audit data from (NOT NULL)
43 */
44 static void audit_cb(struct audit_buffer *ab, void *va)
45 {
46 struct common_audit_data *sa = va;
47
48 audit_log_format(ab, " capname=");
49 audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
50 }
51
52 /**
53 * audit_caps - audit a capability
54 * @ad: audit data
55 * @profile: profile being tested for confinement (NOT NULL)
56 * @cap: capability tested
57 * @error: error code returned by test
58 *
59 * Do auditing of capability and handle, audit/complain/kill modes switching
60 * and duplicate message elimination.
61 *
62 * Returns: 0 or ad->error on success, error code on failure
63 */
64 static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile,
65 int cap, int error)
66 {
67 struct aa_ruleset *rules = list_first_entry(&profile->rules,
68 typeof(*rules), list);
69 struct audit_cache *ent;
70 int type = AUDIT_APPARMOR_AUTO;
71
72 ad->error = error;
73
74 if (likely(!error)) {
75 /* test if auditing is being forced */
76 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
77 !cap_raised(rules->caps.audit, cap)))
78 return 0;
79 type = AUDIT_APPARMOR_AUDIT;
80 } else if (KILL_MODE(profile) ||
81 cap_raised(rules->caps.kill, cap)) {
82 type = AUDIT_APPARMOR_KILL;
83 } else if (cap_raised(rules->caps.quiet, cap) &&
84 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
85 AUDIT_MODE(profile) != AUDIT_ALL) {
86 /* quiet auditing */
87 return error;
88 }
89
90 /* Do simple duplicate message elimination */
91 ent = &get_cpu_var(audit_cache);
92 if (profile == ent->profile && cap_raised(ent->caps, cap)) {
93 put_cpu_var(audit_cache);
94 if (COMPLAIN_MODE(profile))
95 return complain_error(error);
96 return error;
97 } else {
98 aa_put_profile(ent->profile);
99 ent->profile = aa_get_profile(profile);
100 cap_raise(ent->caps, cap);
101 }
102 put_cpu_var(audit_cache);
103
104 return aa_audit(type, profile, ad, audit_cb);
105 }
106
107 /**
108 * profile_capable - test if profile allows use of capability @cap
109 * @profile: profile being enforced (NOT NULL, NOT unconfined)
110 * @cap: capability to test if allowed
111 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
112 * @ad: audit data (MAY BE NULL indicating no auditing)
113 *
114 * Returns: 0 if allowed else -EPERM
115 */
116 static int profile_capable(struct aa_profile *profile, int cap,
117 unsigned int opts, struct apparmor_audit_data *ad)
118 {
119 struct aa_ruleset *rules = list_first_entry(&profile->rules,
120 typeof(*rules), list);
121 int error;
122
123 if (cap_raised(rules->caps.allow, cap) &&
124 !cap_raised(rules->caps.denied, cap))
125 error = 0;
126 else
127 error = -EPERM;
128
129 if (opts & CAP_OPT_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 ad->info = "optional: no audit";
136 }
137
138 return audit_caps(ad, profile, cap, error);
139 }
140
141 /**
142 * aa_capable - test permission to use capability
143 * @subj_cred: cred we are testing capability against
144 * @label: label being tested for capability (NOT NULL)
145 * @cap: capability to be tested
146 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
147 *
148 * Look up capability in profile capability set.
149 *
150 * Returns: 0 on success, or else an error code.
151 */
152 int aa_capable(const struct cred *subj_cred, struct aa_label *label,
153 int cap, unsigned int opts)
154 {
155 struct aa_profile *profile;
156 int error = 0;
157 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_CAP, AA_CLASS_CAP, OP_CAPABLE);
158
159 ad.subj_cred = subj_cred;
160 ad.common.u.cap = cap;
161 error = fn_for_each_confined(label, profile,
162 profile_capable(profile, cap, opts, &ad));
163
164 return error;
165 }
166
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