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 #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_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  * @audit: whether an audit record should be 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, int audit,
 119                            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 (audit == SECURITY_CAP_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  * @audit: whether an audit record should be 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, int audit)
 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, audit, &sa));
 160
 161         return error;
 162 }