security/apparmor/capability.c

   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
  19 #include "include/apparmor.h"
  20 #include "include/capability.h"
  21 #include "include/context.h"
  22 #include "include/policy.h"
  23 #include "include/audit.h"
  24
  25 /*
  26  * Table of capability names: we generate it from capabilities.h.
  27  */
  28 #include "capability_names.h"
  29
  30 struct aa_fs_entry aa_fs_entry_caps[] = {
  31         AA_FS_FILE_STRING("mask", AA_FS_CAPS_MASK),
  32         { }
  33 };
  34
  35 struct audit_cache {
  36         struct aa_profile *profile;
  37         kernel_cap_t caps;
  38 };
  39
  40 static 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  */
  47 static void audit_cb(struct audit_buffer *ab, void *va)
  48 {
  49         struct common_audit_data *sa = va;
  50         audit_log_format(ab, " capname=");
  51         audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
  52 }
  53
  54 /**
  55  * audit_caps - audit a capability
  56  * @sa: audit data
  57  * @profile: profile being tested for confinement (NOT NULL)
  58  * @cap: capability tested
  59  * @error: error code returned by test
  60  *
  61  * Do auditing of capability and handle, audit/complain/kill modes switching
  62  * and duplicate message elimination.
  63  *
  64  * Returns: 0 or sa->error on success,  error code on failure
  65  */
  66 static int audit_caps(struct common_audit_data *sa, struct aa_profile *profile,
  67                       int cap, int error)
  68 {
  69         struct audit_cache *ent;
  70         int type = AUDIT_APPARMOR_AUTO;
  71         aad(sa)->error = error;
  72
  73         if (likely(!error)) {
  74                 /* test if auditing is being forced */
  75                 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
  76                            !cap_raised(profile->caps.audit, cap)))
  77                         return 0;
  78                 type = AUDIT_APPARMOR_AUDIT;
  79         } else if (KILL_MODE(profile) ||
  80                    cap_raised(profile->caps.kill, cap)) {
  81                 type = AUDIT_APPARMOR_KILL;
  82         } else if (cap_raised(profile->caps.quiet, cap) &&
  83                    AUDIT_MODE(profile) != AUDIT_NOQUIET &&
  84                    AUDIT_MODE(profile) != AUDIT_ALL) {
  85                 /* quiet auditing */
  86                 return error;
  87         }
  88
  89         /* Do simple duplicate message elimination */
  90         ent = &get_cpu_var(audit_cache);
  91         if (profile == ent->profile && cap_raised(ent->caps, cap)) {
  92                 put_cpu_var(audit_cache);
  93                 if (COMPLAIN_MODE(profile))
  94                         return complain_error(error);
  95                 return error;
  96         } else {
  97                 aa_put_profile(ent->profile);
  98                 ent->profile = aa_get_profile(profile);
  99                 cap_raise(ent->caps, cap);
 100         }
 101         put_cpu_var(audit_cache);
 102
 103         return aa_audit(type, profile, sa, audit_cb);
 104 }
 105
 106 /**
 107  * profile_capable - test if profile allows use of capability @cap
 108  * @profile: profile being enforced    (NOT NULL, NOT unconfined)
 109  * @cap: capability to test if allowed
 110  * @audit: whether an audit record should be generated
 111  * @sa: audit data (MAY BE NULL indicating no auditing)
 112  *
 113  * Returns: 0 if allowed else -EPERM
 114  */
 115 static int profile_capable(struct aa_profile *profile, int cap, int audit,
 116                            struct common_audit_data *sa)
 117 {
 118        int error;
 119
 120        if (cap_raised(profile->caps.allow, cap) &&
 121            !cap_raised(profile->caps.denied, cap))
 122                error = 0;
 123        else
 124                error = -EPERM;
 125
 126        if (audit == SECURITY_CAP_NOAUDIT) {
 127                if (!COMPLAIN_MODE(profile))
 128                        return error;
 129                /* audit the cap request in complain mode but note that it
 130                 * should be optional.
 131                 */
 132                aad(sa)->info = "optional: no audit";
 133        }
 134
 135        return audit_caps(sa, profile, cap, error);
 136 }
 137
 138 /**
 139  * aa_capable - test permission to use capability
 140  * @label: label being tested for capability (NOT NULL)
 141  * @cap: capability to be tested
 142  * @audit: whether an audit record should be generated
 143  *
 144  * Look up capability in profile capability set.
 145  *
 146  * Returns: 0 on success, or else an error code.
 147  */
 148 int aa_capable(struct aa_label *label, int cap, int audit)
 149 {
 150         struct aa_profile *profile;
 151         int error = 0;
 152         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_CAP, OP_CAPABLE);
 153         sa.u.cap = cap;
 154
 155         error = fn_for_each_confined(label, profile,
 156                         profile_capable(profile, cap, audit, &sa));
 157
 158         return error;
 159 }