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#include <linux/timekeeping.h>
16
17#include "include/apparmor.h"
18#include "include/capability.h"
19#include "include/cred.h"
20#include "include/policy.h"
21#include "include/audit.h"
22
23/*
24 * Table of capability names: we generate it from capabilities.h.
25 */
26#include "capability_names.h"
27
28struct aa_sfs_entry aa_sfs_entry_caps[] = {
29 AA_SFS_FILE_STRING("mask", AA_SFS_CAPS_MASK),
30 { }
31};
32
33struct audit_cache {
34 const struct cred *ad_subj_cred;
35 /* Capabilities go from 0 to CAP_LAST_CAP */
36 u64 ktime_ns_expiration[CAP_LAST_CAP+1];
37};
38
39static DEFINE_PER_CPU(struct audit_cache, audit_cache);
40
41/**
42 * audit_cb - call back for capability components of audit struct
43 * @ab: audit buffer (NOT NULL)
44 * @va: audit struct to audit data from (NOT NULL)
45 */
46static void audit_cb(struct audit_buffer *ab, void *va)
47{
48 struct common_audit_data *sa = va;
49
50 audit_log_format(ab, fmt: " capname=");
51 audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
52}
53
54/**
55 * audit_caps - audit a capability
56 * @ad: audit data
57 * @profile: profile being tested for confinement (NOT NULL)
58 * @cap: capability tested
59 * @error: error code returned by test
60 *
61 * Do auditing of capability and handle, audit/complain/kill modes switching
62 * and duplicate message elimination.
63 *
64 * Returns: 0 or ad->error on success, error code on failure
65 */
66static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile,
67 int cap, int error)
68{
69 const u64 AUDIT_CACHE_TIMEOUT_NS = 1000*1000*1000; /* 1 second */
70
71 struct aa_ruleset *rules = list_first_entry(&profile->rules,
72 typeof(*rules), list);
73 struct audit_cache *ent;
74 int type = AUDIT_APPARMOR_AUTO;
75
76 ad->error = error;
77
78 if (likely(!error)) {
79 /* test if auditing is being forced */
80 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
81 !cap_raised(rules->caps.audit, cap)))
82 return 0;
83 type = AUDIT_APPARMOR_AUDIT;
84 } else if (KILL_MODE(profile) ||
85 cap_raised(rules->caps.kill, cap)) {
86 type = AUDIT_APPARMOR_KILL;
87 } else if (cap_raised(rules->caps.quiet, cap) &&
88 AUDIT_MODE(profile) != AUDIT_NOQUIET &&
89 AUDIT_MODE(profile) != AUDIT_ALL) {
90 /* quiet auditing */
91 return error;
92 }
93
94 /* Do simple duplicate message elimination */
95 ent = &get_cpu_var(audit_cache);
96 /* If the capability was never raised the timestamp check would also catch that */
97 if (ad->subj_cred == ent->ad_subj_cred && ktime_get_ns() <= ent->ktime_ns_expiration[cap]) {
98 put_cpu_var(audit_cache);
99 if (COMPLAIN_MODE(profile))
100 return complain_error(error);
101 return error;
102 } else {
103 put_cred(cred: ent->ad_subj_cred);
104 ent->ad_subj_cred = get_cred(cred: ad->subj_cred);
105 ent->ktime_ns_expiration[cap] = ktime_get_ns() + AUDIT_CACHE_TIMEOUT_NS;
106 }
107 put_cpu_var(audit_cache);
108
109 return aa_audit(type, profile, ad, cb: audit_cb);
110}
111
112/**
113 * profile_capable - test if profile allows use of capability @cap
114 * @profile: profile being enforced (NOT NULL, NOT unconfined)
115 * @cap: capability to test if allowed
116 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
117 * @ad: audit data (NOT NULL)
118 *
119 * Returns: 0 if allowed else -EPERM
120 */
121static int profile_capable(struct aa_profile *profile, int cap,
122 unsigned int opts, struct apparmor_audit_data *ad)
123{
124 struct aa_ruleset *rules = list_first_entry(&profile->rules,
125 typeof(*rules), list);
126 int error;
127
128 if (cap_raised(rules->caps.allow, cap) &&
129 !cap_raised(rules->caps.denied, cap))
130 error = 0;
131 else
132 error = -EPERM;
133
134 if (opts & CAP_OPT_NOAUDIT) {
135 if (!COMPLAIN_MODE(profile))
136 return error;
137 /* audit the cap request in complain mode but note that it
138 * should be optional.
139 */
140 ad->info = "optional: no audit";
141 }
142
143 return audit_caps(ad, profile, cap, error);
144}
145
146/**
147 * aa_capable - test permission to use capability
148 * @subj_cred: cred we are testing capability against
149 * @label: label being tested for capability (NOT NULL)
150 * @cap: capability to be tested
151 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
152 *
153 * Look up capability in profile capability set.
154 *
155 * Returns: 0 on success, or else an error code.
156 */
157int aa_capable(const struct cred *subj_cred, struct aa_label *label,
158 int cap, unsigned int opts)
159{
160 struct aa_profile *profile;
161 int error = 0;
162 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_CAP, AA_CLASS_CAP, OP_CAPABLE);
163
164 ad.subj_cred = subj_cred;
165 ad.common.u.cap = cap;
166 error = fn_for_each_confined(label, profile,
167 profile_capable(profile, cap, opts, &ad));
168
169 return error;
170}
171

source code of linux/security/apparmor/capability.c