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/context.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_fs_entry aa_fs_entry_caps[] = {
32 	AA_FS_FILE_STRING("mask", AA_FS_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 	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  * @profile: profile being tested for confinement (NOT NULL)
58  * @cap: capability tested
59  @audit: whether an audit record should be generated
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 sa->error on success,  error code on failure
66  */
67 static int audit_caps(struct aa_profile *profile, int cap, int audit,
68 		      int error)
69 {
70 	struct audit_cache *ent;
71 	int type = AUDIT_APPARMOR_AUTO;
72 	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_CAP, OP_CAPABLE);
73 	sa.u.cap = cap;
74 	aad(&sa)->error = error;
75 	if (audit == SECURITY_CAP_NOAUDIT)
76 		aad(&sa)->info = "optional: no audit";
77 
78 	if (likely(!error)) {
79 		/* test if auditing is being forced */
80 		if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
81 			   !cap_raised(profile->caps.audit, cap)))
82 			return 0;
83 		type = AUDIT_APPARMOR_AUDIT;
84 	} else if (KILL_MODE(profile) ||
85 		   cap_raised(profile->caps.kill, cap)) {
86 		type = AUDIT_APPARMOR_KILL;
87 	} else if (cap_raised(profile->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 (profile == ent->profile && cap_raised(ent->caps, cap)) {
97 		put_cpu_var(audit_cache);
98 		if (COMPLAIN_MODE(profile))
99 			return complain_error(error);
100 		return error;
101 	} else {
102 		aa_put_profile(ent->profile);
103 		ent->profile = aa_get_profile(profile);
104 		cap_raise(ent->caps, cap);
105 	}
106 	put_cpu_var(audit_cache);
107 
108 	return aa_audit(type, profile, &sa, audit_cb);
109 }
110 
111 /**
112  * profile_capable - test if profile allows use of capability @cap
113  * @profile: profile being enforced    (NOT NULL, NOT unconfined)
114  * @cap: capability to test if allowed
115  *
116  * Returns: 0 if allowed else -EPERM
117  */
118 static int profile_capable(struct aa_profile *profile, int cap)
119 {
120 	return cap_raised(profile->caps.allow, cap) ? 0 : -EPERM;
121 }
122 
123 /**
124  * aa_capable - test permission to use capability
125  * @profile: profile being tested against (NOT NULL)
126  * @cap: capability to be tested
127  * @audit: whether an audit record should be generated
128  *
129  * Look up capability in profile capability set.
130  *
131  * Returns: 0 on success, or else an error code.
132  */
133 int aa_capable(struct aa_profile *profile, int cap, int audit)
134 {
135 	int error = profile_capable(profile, cap);
136 
137 	if (audit == SECURITY_CAP_NOAUDIT) {
138 		if (!COMPLAIN_MODE(profile))
139 			return error;
140 	}
141 
142 	return audit_caps(profile, cap, audit, error);
143 }
144