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 #define AA_FIRST_SECID 2
  36
  37 static DEFINE_IDR(aa_secids);
  38 static DEFINE_SPINLOCK(secid_lock);
  39
  40 /*
  41  * TODO: allow policy to reserve a secid range?
  42  * TODO: add secid pinning
  43  * TODO: use secid_update in label replace
  44  */
  45
  46 /**
  47  * aa_secid_update - update a secid mapping to a new label
  48  * @secid: secid to update
  49  * @label: label the secid will now map to
  50  */
  51 void aa_secid_update(u32 secid, struct aa_label *label)
  52 {
  53         unsigned long flags;
  54
  55         spin_lock_irqsave(&secid_lock, flags);
  56         idr_replace(&aa_secids, label, secid);
  57         spin_unlock_irqrestore(&secid_lock, flags);
  58 }
  59
  60 /**
  61  *
  62  * see label for inverse aa_label_to_secid
  63  */
  64 struct aa_label *aa_secid_to_label(u32 secid)
  65 {
  66         struct aa_label *label;
  67
  68         rcu_read_lock();
  69         label = idr_find(&aa_secids, secid);
  70         rcu_read_unlock();
  71
  72         return label;
  73 }
  74
  75 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
  76 {
  77         /* TODO: cache secctx and ref count so we don't have to recreate */
  78         struct aa_label *label = aa_secid_to_label(secid);
  79         int len;
  80
  81         AA_BUG(!seclen);
  82
  83         if (!label)
  84                 return -EINVAL;
  85
  86         if (secdata)
  87                 len = aa_label_asxprint(secdata, root_ns, label,
  88                                         FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  89                                         FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT,
  90                                         GFP_ATOMIC);
  91         else
  92                 len = aa_label_snxprint(NULL, 0, root_ns, label,
  93                                         FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  94                                         FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT);
  95         if (len < 0)
  96                 return -ENOMEM;
  97
  98         *seclen = len;
  99
 100         return 0;
 101 }
 102
 103 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 104 {
 105         struct aa_label *label;
 106
 107         label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
 108                                     seclen, GFP_KERNEL, false, false);
 109         if (IS_ERR(label))
 110                 return PTR_ERR(label);
 111         *secid = label->secid;
 112
 113         return 0;
 114 }
 115
 116 void apparmor_release_secctx(char *secdata, u32 seclen)
 117 {
 118         kfree(secdata);
 119 }
 120
 121 /**
 122  * aa_alloc_secid - allocate a new secid for a profile
 123  * @label: the label to allocate a secid for
 124  * @gfp: memory allocation flags
 125  *
 126  * Returns: 0 with @label->secid initialized
 127  *          <0 returns error with @label->secid set to AA_SECID_INVALID
 128  */
 129 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
 130 {
 131         unsigned long flags;
 132         int ret;
 133
 134         idr_preload(gfp);
 135         spin_lock_irqsave(&secid_lock, flags);
 136         ret = idr_alloc(&aa_secids, label, AA_FIRST_SECID, 0, GFP_ATOMIC);
 137         spin_unlock_irqrestore(&secid_lock, flags);
 138         idr_preload_end();
 139
 140         if (ret < 0) {
 141                 label->secid = AA_SECID_INVALID;
 142                 return ret;
 143         }
 144
 145         AA_BUG(ret == AA_SECID_INVALID);
 146         label->secid = ret;
 147         return 0;
 148 }
 149
 150 /**
 151  * aa_free_secid - free a secid
 152  * @secid: secid to free
 153  */
 154 void aa_free_secid(u32 secid)
 155 {
 156         unsigned long flags;
 157
 158         spin_lock_irqsave(&secid_lock, flags);
 159         idr_remove(&aa_secids, secid);
 160         spin_unlock_irqrestore(&secid_lock, flags);
 161 }
 162
 163 void aa_secids_init(void)
 164 {
 165         idr_init_base(&aa_secids, AA_FIRST_SECID);
 166 }