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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 AA_SFS_FILE_BOOLEAN("extended", 1),
31 { }
32};
33
34struct audit_cache {
35 const struct cred *ad_subj_cred;
36 /* Capabilities go from 0 to CAP_LAST_CAP */
37 u64 ktime_ns_expiration[CAP_LAST_CAP+1];
38};
39
40static DEFINE_PER_CPU(struct audit_cache, audit_cache);
41
42/**
43 * audit_cb - call back for capability components of audit struct
44 * @ab: audit buffer (NOT NULL)
45 * @va: audit struct to audit data from (NOT NULL)
46 */
47static void audit_cb(struct audit_buffer *ab, void *va)
48{
49 struct common_audit_data *sa = va;
50
51 audit_log_format(ab, " capname=");
52 audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
53}
54
55/**
56 * audit_caps - audit a capability
57 * @ad: audit data
58 * @profile: profile being tested for confinement (NOT NULL)
59 * @cap: capability tested
60 * @error: error code returned by test
61 *
62 * Do auditing of capability and handle, audit/complain/kill modes switching
63 * and duplicate message elimination.
64 *
65 * Returns: 0 or ad->error on success, error code on failure
66 */
67static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile,
68 int cap, int error)
69{
70 const u64 AUDIT_CACHE_TIMEOUT_NS = 1000*1000*1000; /* 1 second */
71
72 struct aa_ruleset *rules = profile->label.rules[0];
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(ent->ad_subj_cred);
104 ent->ad_subj_cred = get_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, 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 = profile->label.rules[0];
125 aa_state_t state;
126 int error;
127
128 state = RULE_MEDIATES(rules, ad->class);
129 if (state) {
130 struct aa_perms perms = { };
131 u32 request;
132
133 /* caps broken into 256 x 32 bit permission chunks */
134 state = aa_dfa_next(rules->policy->dfa, state, cap >> 5);
135 request = 1 << (cap & 0x1f);
136 perms = *aa_lookup_perms(rules->policy, state);
137 aa_apply_modes_to_perms(profile, &perms);
138
139 if (opts & CAP_OPT_NOAUDIT) {
140 if (perms.complain & request)
141 ad->info = "optional: no audit";
142 else
143 ad = NULL;
144 }
145 return aa_check_perms(profile, &perms, request, ad,
146 audit_cb);
147 }
148
149 /* fallback to old caps mediation that doesn't support conditionals */
150 if (cap_raised(rules->caps.allow, cap) &&
151 !cap_raised(rules->caps.denied, cap))
152 error = 0;
153 else
154 error = -EPERM;
155
156 if (opts & CAP_OPT_NOAUDIT) {
157 if (!COMPLAIN_MODE(profile))
158 return error;
159 /* audit the cap request in complain mode but note that it
160 * should be optional.
161 */
162 ad->info = "optional: no audit";
163 }
164
165 return audit_caps(ad, profile, cap, error);
166}
167
168/**
169 * aa_capable - test permission to use capability
170 * @subj_cred: cred we are testing capability against
171 * @label: label being tested for capability (NOT NULL)
172 * @cap: capability to be tested
173 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
174 *
175 * Look up capability in profile capability set.
176 *
177 * Returns: 0 on success, or else an error code.
178 */
179int aa_capable(const struct cred *subj_cred, struct aa_label *label,
180 int cap, unsigned int opts)
181{
182 struct aa_profile *profile;
183 int error = 0;
184 DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_CAP, AA_CLASS_CAP, OP_CAPABLE);
185
186 ad.subj_cred = subj_cred;
187 ad.common.u.cap = cap;
188 error = fn_for_each_confined(label, profile,
189 profile_capable(profile, cap, opts, &ad));
190
191 return error;
192}
193
194kernel_cap_t aa_profile_capget(const struct aa_profile *profile)
195{
196 struct aa_ruleset *rules = profile->label.rules[0];
197 aa_state_t state;
198
199 state = RULE_MEDIATES(rules, AA_CLASS_CAP);
200 if (state) {
201 kernel_cap_t caps = CAP_EMPTY_SET;
202 int i;
203
204 /* caps broken into up to 256, 32 bit permission chunks */
205 for (i = 0; i < (CAP_LAST_CAP >> 5); i++) {
206 struct aa_perms perms = { };
207 aa_state_t tmp;
208
209 tmp = aa_dfa_next(rules->policy->dfa, state, i);
210 perms = *aa_lookup_perms(rules->policy, tmp);
211 aa_apply_modes_to_perms(profile, &perms);
212 caps.val |= ((u64)(perms.allow)) << (i * 5);
213 caps.val |= ((u64)(perms.complain)) << (i * 5);
214 }
215 return caps;
216 }
217
218 /* fallback to old caps */
219 if (COMPLAIN_MODE(profile))
220 return CAP_FULL_SET;
221
222 return rules->caps.allow;
223}