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