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  * @profile: profile confining task (NOT NULL)
  57  * @task: task capability test was performed against (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 aa_profile *profile, struct task_struct *task,
  67                       int cap, int error)
  68 {
  69         struct audit_cache *ent;
  70         int type = AUDIT_APPARMOR_AUTO;
  71         struct common_audit_data sa;
  72         struct apparmor_audit_data aad = {0,};
  73         sa.type = LSM_AUDIT_DATA_CAP;
  74         sa.aad = &aad;
  75         sa.u.cap = cap;
  76         sa.aad->tsk = task;
  77         sa.aad->op = OP_CAPABLE;
  78         sa.aad->error = error;
  79
  80         if (likely(!error)) {
  81                 /* test if auditing is being forced */
  82                 if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
  83                            !cap_raised(profile->caps.audit, cap)))
  84                         return 0;
  85                 type = AUDIT_APPARMOR_AUDIT;
  86         } else if (KILL_MODE(profile) ||
  87                    cap_raised(profile->caps.kill, cap)) {
  88                 type = AUDIT_APPARMOR_KILL;
  89         } else if (cap_raised(profile->caps.quiet, cap) &&
  90                    AUDIT_MODE(profile) != AUDIT_NOQUIET &&
  91                    AUDIT_MODE(profile) != AUDIT_ALL) {
  92                 /* quiet auditing */
  93                 return error;
  94         }
  95
  96         /* Do simple duplicate message elimination */
  97         ent = &get_cpu_var(audit_cache);
  98         if (profile == ent->profile && cap_raised(ent->caps, cap)) {
  99                 put_cpu_var(audit_cache);
 100                 if (COMPLAIN_MODE(profile))
 101                         return complain_error(error);
 102                 return error;
 103         } else {
 104                 aa_put_profile(ent->profile);
 105                 ent->profile = aa_get_profile(profile);
 106                 cap_raise(ent->caps, cap);
 107         }
 108         put_cpu_var(audit_cache);
 109
 110         return aa_audit(type, profile, GFP_ATOMIC, &sa, audit_cb);
 111 }
 112
 113 /**
 114  * profile_capable - test if profile allows use of capability @cap
 115  * @profile: profile being enforced    (NOT NULL, NOT unconfined)
 116  * @cap: capability to test if allowed
 117  *
 118  * Returns: 0 if allowed else -EPERM
 119  */
 120 static int profile_capable(struct aa_profile *profile, int cap)
 121 {
 122         return cap_raised(profile->caps.allow, cap) ? 0 : -EPERM;
 123 }
 124
 125 /**
 126  * aa_capable - test permission to use capability
 127  * @task: task doing capability test against (NOT NULL)
 128  * @profile: profile confining @task (NOT NULL)
 129  * @cap: capability to be tested
 130  * @audit: whether an audit record should be generated
 131  *
 132  * Look up capability in profile capability set.
 133  *
 134  * Returns: 0 on success, or else an error code.
 135  */
 136 int aa_capable(struct task_struct *task, struct aa_profile *profile, int cap,
 137                int audit)
 138 {
 139         int error = profile_capable(profile, cap);
 140
 141         if (!audit) {
 142                 if (COMPLAIN_MODE(profile))
 143                         return complain_error(error);
 144                 return error;
 145         }
 146
 147         return audit_caps(profile, task, cap, error);
 148 }