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 audit_cache {
  31         struct aa_profile *profile;
  32         kernel_cap_t caps;
  33 };
  34
  35 static DEFINE_PER_CPU(struct audit_cache, audit_cache);
  36
  37 /**
  38  * audit_cb - call back for capability components of audit struct
  39  * @ab - audit buffer   (NOT NULL)
  40  * @va - audit struct to audit data from  (NOT NULL)
  41  */
  42 static void audit_cb(struct audit_buffer *ab, void *va)
  43 {
  44         struct common_audit_data *sa = va;
  45         audit_log_format(ab, " capname=");
  46         audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
  47 }
  48
  49 /**
  50  * audit_caps - audit a capability
  51  * @profile: profile confining task (NOT NULL)
  52  * @task: task capability test was performed against (NOT NULL)
  53  * @cap: capability tested
  54  * @error: error code returned by test
  55  *
  56  * Do auditing of capability and handle, audit/complain/kill modes switching
  57  * and duplicate message elimination.
  58  *
  59  * Returns: 0 or sa->error on success,  error code on failure
  60  */
  61 static int audit_caps(struct aa_profile *profile, struct task_struct *task,
  62                       int cap, int error)
  63 {
  64         struct audit_cache *ent;
  65         int type = AUDIT_APPARMOR_AUTO;
  66         struct common_audit_data sa;
  67         COMMON_AUDIT_DATA_INIT(&sa, CAP);
  68         sa.tsk = task;
  69         sa.u.cap = cap;
  70         sa.aad.op = OP_CAPABLE;
  71         sa.aad.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, GFP_ATOMIC, &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  *
 111  * Returns: 0 if allowed else -EPERM
 112  */
 113 static int profile_capable(struct aa_profile *profile, int cap)
 114 {
 115         return cap_raised(profile->caps.allow, cap) ? 0 : -EPERM;
 116 }
 117
 118 /**
 119  * aa_capable - test permission to use capability
 120  * @task: task doing capability test against (NOT NULL)
 121  * @profile: profile confining @task (NOT NULL)
 122  * @cap: capability to be tested
 123  * @audit: whether an audit record should be generated
 124  *
 125  * Look up capability in profile capability set.
 126  *
 127  * Returns: 0 on success, or else an error code.
 128  */
 129 int aa_capable(struct task_struct *task, struct aa_profile *profile, int cap,
 130                int audit)
 131 {
 132         int error = profile_capable(profile, cap);
 133
 134         if (!audit) {
 135                 if (COMPLAIN_MODE(profile))
 136                         return complain_error(error);
 137                 return error;
 138         }
 139
 140         return audit_caps(profile, task, cap, error);
 141 }