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  */
audit_cb(struct audit_buffer * ab,void * va)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  * @sa: 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 sa->error on success,  error code on failure
63  */
audit_caps(struct common_audit_data * sa,struct aa_profile * profile,int cap,int error)64 static int audit_caps(struct common_audit_data *sa, struct aa_profile *profile,
65 		      int cap, int error)
66 {
67 	struct audit_cache *ent;
68 	int type = AUDIT_APPARMOR_AUTO;
69 
70 	aad(sa)->error = error;
71 
72 	if (likely(!error)) {
73 		/* test if auditing is being forced */
74 		if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
75 			   !cap_raised(profile->caps.audit, cap)))
76 			return 0;
77 		type = AUDIT_APPARMOR_AUDIT;
78 	} else if (KILL_MODE(profile) ||
79 		   cap_raised(profile->caps.kill, cap)) {
80 		type = AUDIT_APPARMOR_KILL;
81 	} else if (cap_raised(profile->caps.quiet, cap) &&
82 		   AUDIT_MODE(profile) != AUDIT_NOQUIET &&
83 		   AUDIT_MODE(profile) != AUDIT_ALL) {
84 		/* quiet auditing */
85 		return error;
86 	}
87 
88 	/* Do simple duplicate message elimination */
89 	ent = &get_cpu_var(audit_cache);
90 	if (profile == ent->profile && cap_raised(ent->caps, cap)) {
91 		put_cpu_var(audit_cache);
92 		if (COMPLAIN_MODE(profile))
93 			return complain_error(error);
94 		return error;
95 	} else {
96 		aa_put_profile(ent->profile);
97 		ent->profile = aa_get_profile(profile);
98 		cap_raise(ent->caps, cap);
99 	}
100 	put_cpu_var(audit_cache);
101 
102 	return aa_audit(type, profile, sa, audit_cb);
103 }
104 
105 /**
106  * profile_capable - test if profile allows use of capability @cap
107  * @profile: profile being enforced    (NOT NULL, NOT unconfined)
108  * @cap: capability to test if allowed
109  * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
110  * @sa: audit data (MAY BE NULL indicating no auditing)
111  *
112  * Returns: 0 if allowed else -EPERM
113  */
profile_capable(struct aa_profile * profile,int cap,unsigned int opts,struct common_audit_data * sa)114 static int profile_capable(struct aa_profile *profile, int cap,
115 			   unsigned int opts, struct common_audit_data *sa)
116 {
117 	int error;
118 
119 	if (cap_raised(profile->caps.allow, cap) &&
120 	    !cap_raised(profile->caps.denied, cap))
121 		error = 0;
122 	else
123 		error = -EPERM;
124 
125 	if (opts & CAP_OPT_NOAUDIT) {
126 		if (!COMPLAIN_MODE(profile))
127 			return error;
128 		/* audit the cap request in complain mode but note that it
129 		 * should be optional.
130 		 */
131 		aad(sa)->info = "optional: no audit";
132 	}
133 
134 	return audit_caps(sa, profile, cap, error);
135 }
136 
137 /**
138  * aa_capable - test permission to use capability
139  * @label: label being tested for capability (NOT NULL)
140  * @cap: capability to be tested
141  * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
142  *
143  * Look up capability in profile capability set.
144  *
145  * Returns: 0 on success, or else an error code.
146  */
aa_capable(struct aa_label * label,int cap,unsigned int opts)147 int aa_capable(struct aa_label *label, int cap, unsigned int opts)
148 {
149 	struct aa_profile *profile;
150 	int error = 0;
151 	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_CAP, OP_CAPABLE);
152 
153 	sa.u.cap = cap;
154 	error = fn_for_each_confined(label, profile,
155 			profile_capable(profile, cap, opts, &sa));
156 
157 	return error;
158 }
159