security/apparmor/include/cred.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor contexts used to associate "labels" to objects.
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2010 Canonical Ltd.
   9  */
  10
  11 #ifndef __AA_CONTEXT_H
  12 #define __AA_CONTEXT_H
  13
  14 #include <linux/cred.h>
  15 #include <linux/slab.h>
  16 #include <linux/sched.h>
  17
  18 #include "label.h"
  19 #include "policy_ns.h"
  20 #include "task.h"
  21
  22 static inline struct aa_label *cred_label(const struct cred *cred)
  23 {
  24         struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
  25
  26         AA_BUG(!blob);
  27         return *blob;
  28 }
  29
  30 static inline void set_cred_label(const struct cred *cred,
  31                                   struct aa_label *label)
  32 {
  33         struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
  34
  35         AA_BUG(!blob);
  36         *blob = label;
  37 }
  38
  39 /**
  40  * aa_cred_raw_label - obtain cred's label
  41  * @cred: cred to obtain label from  (NOT NULL)
  42  *
  43  * Returns: confining label
  44  *
  45  * does NOT increment reference count
  46  */
  47 static inline struct aa_label *aa_cred_raw_label(const struct cred *cred)
  48 {
  49         struct aa_label *label = cred_label(cred);
  50
  51         AA_BUG(!label);
  52         return label;
  53 }
  54
  55 /**
  56  * aa_get_newest_cred_label - obtain the newest label on a cred
  57  * @cred: cred to obtain label from (NOT NULL)
  58  *
  59  * Returns: newest version of confining label
  60  */
  61 static inline struct aa_label *aa_get_newest_cred_label(const struct cred *cred)
  62 {
  63         return aa_get_newest_label(aa_cred_raw_label(cred));
  64 }
  65
  66 static inline struct aa_label *aa_get_newest_cred_label_condref(const struct cred *cred,
  67                                                                 bool *needput)
  68 {
  69         struct aa_label *l = aa_cred_raw_label(cred);
  70
  71         if (unlikely(label_is_stale(l))) {
  72                 *needput = true;
  73                 return aa_get_newest_label(l);
  74         }
  75
  76         *needput = false;
  77         return l;
  78 }
  79
  80 static inline void aa_put_label_condref(struct aa_label *l, bool needput)
  81 {
  82         if (unlikely(needput))
  83                 aa_put_label(l);
  84 }
  85
  86 /**
  87  * aa_current_raw_label - find the current tasks confining label
  88  *
  89  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
  90  *
  91  * This fn will not update the tasks cred to the most up to date version
  92  * of the label so it is safe to call when inside of locks.
  93  */
  94 static inline struct aa_label *aa_current_raw_label(void)
  95 {
  96         return aa_cred_raw_label(current_cred());
  97 }
  98
  99 /**
 100  * aa_get_current_label - get the newest version of the current tasks label
 101  *
 102  * Returns: newest version of confining label (NOT NULL)
 103  *
 104  * This fn will not update the tasks cred, so it is safe inside of locks
 105  *
 106  * The returned reference must be put with aa_put_label()
 107  */
 108 static inline struct aa_label *aa_get_current_label(void)
 109 {
 110         struct aa_label *l = aa_current_raw_label();
 111
 112         if (label_is_stale(l))
 113                 return aa_get_newest_label(l);
 114         return aa_get_label(l);
 115 }
 116
 117 #define __end_current_label_crit_section(X) end_current_label_crit_section(X)
 118
 119 /**
 120  * end_label_crit_section - put a reference found with begin_current_label..
 121  * @label: label reference to put
 122  *
 123  * Should only be used with a reference obtained with
 124  * begin_current_label_crit_section and never used in situations where the
 125  * task cred may be updated
 126  */
 127 static inline void end_current_label_crit_section(struct aa_label *label)
 128 {
 129         if (label != aa_current_raw_label())
 130                 aa_put_label(label);
 131 }
 132
 133 /**
 134  * __begin_current_label_crit_section - current's confining label
 135  *
 136  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
 137  *
 138  * safe to call inside locks
 139  *
 140  * The returned reference must be put with __end_current_label_crit_section()
 141  * This must NOT be used if the task cred could be updated within the
 142  * critical section between __begin_current_label_crit_section() ..
 143  * __end_current_label_crit_section()
 144  */
 145 static inline struct aa_label *__begin_current_label_crit_section(void)
 146 {
 147         struct aa_label *label = aa_current_raw_label();
 148
 149         if (label_is_stale(label))
 150                 label = aa_get_newest_label(label);
 151
 152         return label;
 153 }
 154
 155 /**
 156  * begin_current_label_crit_section - current's confining label and update it
 157  *
 158  * Returns: up to date confining label or the ns unconfined label (NOT NULL)
 159  *
 160  * Not safe to call inside locks
 161  *
 162  * The returned reference must be put with end_current_label_crit_section()
 163  * This must NOT be used if the task cred could be updated within the
 164  * critical section between begin_current_label_crit_section() ..
 165  * end_current_label_crit_section()
 166  */
 167 static inline struct aa_label *begin_current_label_crit_section(void)
 168 {
 169         struct aa_label *label = aa_current_raw_label();
 170
 171         might_sleep();
 172
 173         if (label_is_stale(label)) {
 174                 label = aa_get_newest_label(label);
 175                 if (aa_replace_current_label(label) == 0)
 176                         /* task cred will keep the reference */
 177                         aa_put_label(label);
 178         }
 179
 180         return label;
 181 }
 182
 183 static inline struct aa_ns *aa_get_current_ns(void)
 184 {
 185         struct aa_label *label;
 186         struct aa_ns *ns;
 187
 188         label  = __begin_current_label_crit_section();
 189         ns = aa_get_ns(labels_ns(label));
 190         __end_current_label_crit_section(label);
 191
 192         return ns;
 193 }
 194
 195 #endif /* __AA_CONTEXT_H */