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
27struct aa_sfs_entry aa_sfs_entry_caps[] = {
28	AA_SFS_FILE_STRING("mask", AA_SFS_CAPS_MASK),
29	{ }
30};
31
32struct audit_cache {
33	struct aa_profile *profile;
34	kernel_cap_t caps;
35};
36
37static 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 */
44static 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 */
64static 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 */
116static 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 */
152int 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