security/apparmor/secid.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor security identifier (secid) manipulation fns
   5  *
   6  * Copyright 2009-2017 Canonical Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation, version 2 of the
  11  * License.
  12  *
  13  *
  14  * AppArmor allocates a unique secid for every label used. If a label
  15  * is replaced it receives the secid of the label it is replacing.
  16  */
  17
  18 #include <linux/errno.h>
  19 #include <linux/err.h>
  20 #include <linux/gfp.h>
  21 #include <linux/idr.h>
  22 #include <linux/slab.h>
  23 #include <linux/spinlock.h>
  24
  25 #include "include/cred.h"
  26 #include "include/lib.h"
  27 #include "include/secid.h"
  28 #include "include/label.h"
  29 #include "include/policy_ns.h"
  30
  31 /*
  32  * secids - do not pin labels with a refcount. They rely on the label
  33  * properly updating/freeing them
  34  */
  35
  36 #define AA_FIRST_SECID 1
  37
  38 static DEFINE_IDR(aa_secids);
  39 static DEFINE_SPINLOCK(secid_lock);
  40
  41 /*
  42  * TODO: allow policy to reserve a secid range?
  43  * TODO: add secid pinning
  44  * TODO: use secid_update in label replace
  45  */
  46
  47 /**
  48  * aa_secid_update - update a secid mapping to a new label
  49  * @secid: secid to update
  50  * @label: label the secid will now map to
  51  */
  52 void aa_secid_update(u32 secid, struct aa_label *label)
  53 {
  54         unsigned long flags;
  55
  56         spin_lock_irqsave(&secid_lock, flags);
  57         idr_replace(&aa_secids, label, secid);
  58         spin_unlock_irqrestore(&secid_lock, flags);
  59 }
  60
  61 /**
  62  *
  63  * see label for inverse aa_label_to_secid
  64  */
  65 struct aa_label *aa_secid_to_label(u32 secid)
  66 {
  67         struct aa_label *label;
  68
  69         rcu_read_lock();
  70         label = idr_find(&aa_secids, secid);
  71         rcu_read_unlock();
  72
  73         return label;
  74 }
  75
  76 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
  77 {
  78         /* TODO: cache secctx and ref count so we don't have to recreate */
  79         struct aa_label *label = aa_secid_to_label(secid);
  80         int len;
  81
  82         AA_BUG(!seclen);
  83
  84         if (!label)
  85                 return -EINVAL;
  86
  87         if (secdata)
  88                 len = aa_label_asxprint(secdata, root_ns, label,
  89                                         FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  90                                         FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT,
  91                                         GFP_ATOMIC);
  92         else
  93                 len = aa_label_snxprint(NULL, 0, root_ns, label,
  94                                         FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  95                                         FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT);
  96         if (len < 0)
  97                 return -ENOMEM;
  98
  99         *seclen = len;
 100
 101         return 0;
 102 }
 103
 104 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 105 {
 106         struct aa_label *label;
 107
 108         label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
 109                                     seclen, GFP_KERNEL, false, false);
 110         if (IS_ERR(label))
 111                 return PTR_ERR(label);
 112         *secid = label->secid;
 113
 114         return 0;
 115 }
 116
 117 void apparmor_release_secctx(char *secdata, u32 seclen)
 118 {
 119         kfree(secdata);
 120 }
 121
 122 /**
 123  * aa_alloc_secid - allocate a new secid for a profile
 124  * @label: the label to allocate a secid for
 125  * @gfp: memory allocation flags
 126  *
 127  * Returns: 0 with @label->secid initialized
 128  *          <0 returns error with @label->secid set to AA_SECID_INVALID
 129  */
 130 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
 131 {
 132         unsigned long flags;
 133         int ret;
 134
 135         idr_preload(gfp);
 136         spin_lock_irqsave(&secid_lock, flags);
 137         ret = idr_alloc(&aa_secids, label, AA_FIRST_SECID, 0, GFP_ATOMIC);
 138         spin_unlock_irqrestore(&secid_lock, flags);
 139         idr_preload_end();
 140
 141         if (ret < 0) {
 142                 label->secid = AA_SECID_INVALID;
 143                 return ret;
 144         }
 145
 146         AA_BUG(ret == AA_SECID_INVALID);
 147         label->secid = ret;
 148         return 0;
 149 }
 150
 151 /**
 152  * aa_free_secid - free a secid
 153  * @secid: secid to free
 154  */
 155 void aa_free_secid(u32 secid)
 156 {
 157         unsigned long flags;
 158
 159         spin_lock_irqsave(&secid_lock, flags);
 160         idr_remove(&aa_secids, secid);
 161         spin_unlock_irqrestore(&secid_lock, flags);
 162 }
 163
 164 void aa_secids_init(void)
 165 {
 166         idr_init_base(&aa_secids, AA_FIRST_SECID);
 167 }