security/apparmor/secid.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor security identifier (secid) manipulation fns
   6  *
   7  * Copyright 2009-2017 Canonical Ltd.
   8  *
   9  * AppArmor allocates a unique secid for every label used. If a label
  10  * is replaced it receives the secid of the label it is replacing.
  11  */
  12
  13 #include <linux/errno.h>
  14 #include <linux/err.h>
  15 #include <linux/gfp.h>
  16 #include <linux/slab.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/xarray.h>
  19
  20 #include "include/cred.h"
  21 #include "include/lib.h"
  22 #include "include/secid.h"
  23 #include "include/label.h"
  24 #include "include/policy_ns.h"
  25
  26 /*
  27  * secids - do not pin labels with a refcount. They rely on the label
  28  * properly updating/freeing them
  29  */
  30 #define AA_FIRST_SECID 2
  31
  32 static DEFINE_XARRAY_FLAGS(aa_secids, XA_FLAGS_LOCK_IRQ | XA_FLAGS_TRACK_FREE);
  33
  34 int apparmor_display_secid_mode;
  35
  36 /*
  37  * TODO: allow policy to reserve a secid range?
  38  * TODO: add secid pinning
  39  * TODO: use secid_update in label replace
  40  */
  41
  42 /*
  43  * see label for inverse aa_label_to_secid
  44  */
  45 struct aa_label *aa_secid_to_label(u32 secid)
  46 {
  47         return xa_load(&aa_secids, secid);
  48 }
  49
  50 static int apparmor_label_to_secctx(struct aa_label *label, char **secdata,
  51                                     u32 *seclen)
  52 {
  53         /* TODO: cache secctx and ref count so we don't have to recreate */
  54         int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
  55         int len;
  56
  57         AA_BUG(!seclen);
  58
  59         if (!label)
  60                 return -EINVAL;
  61
  62         if (apparmor_display_secid_mode)
  63                 flags |= FLAG_SHOW_MODE;
  64
  65         if (secdata)
  66                 len = aa_label_asxprint(secdata, root_ns, label,
  67                                         flags, GFP_ATOMIC);
  68         else
  69                 len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
  70
  71         if (len < 0)
  72                 return -ENOMEM;
  73
  74         *seclen = len;
  75
  76         return 0;
  77 }
  78
  79 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
  80 {
  81         struct aa_label *label = aa_secid_to_label(secid);
  82
  83         return apparmor_label_to_secctx(label, secdata, seclen);
  84 }
  85
  86 int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, char **secdata,
  87                                u32 *seclen)
  88 {
  89         struct aa_label *label;
  90
  91         label = prop->apparmor.label;
  92
  93         return apparmor_label_to_secctx(label, secdata, seclen);
  94 }
  95
  96 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
  97 {
  98         struct aa_label *label;
  99
 100         label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
 101                                     seclen, GFP_KERNEL, false, false);
 102         if (IS_ERR(label))
 103                 return PTR_ERR(label);
 104         *secid = label->secid;
 105
 106         return 0;
 107 }
 108
 109 void apparmor_release_secctx(char *secdata, u32 seclen)
 110 {
 111         kfree(secdata);
 112 }
 113
 114 /**
 115  * aa_alloc_secid - allocate a new secid for a profile
 116  * @label: the label to allocate a secid for
 117  * @gfp: memory allocation flags
 118  *
 119  * Returns: 0 with @label->secid initialized
 120  *          <0 returns error with @label->secid set to AA_SECID_INVALID
 121  */
 122 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
 123 {
 124         unsigned long flags;
 125         int ret;
 126
 127         xa_lock_irqsave(&aa_secids, flags);
 128         ret = __xa_alloc(&aa_secids, &label->secid, label,
 129                         XA_LIMIT(AA_FIRST_SECID, INT_MAX), gfp);
 130         xa_unlock_irqrestore(&aa_secids, flags);
 131
 132         if (ret < 0) {
 133                 label->secid = AA_SECID_INVALID;
 134                 return ret;
 135         }
 136
 137         return 0;
 138 }
 139
 140 /**
 141  * aa_free_secid - free a secid
 142  * @secid: secid to free
 143  */
 144 void aa_free_secid(u32 secid)
 145 {
 146         unsigned long flags;
 147
 148         xa_lock_irqsave(&aa_secids, flags);
 149         __xa_erase(&aa_secids, secid);
 150         xa_unlock_irqrestore(&aa_secids, flags);
 151 }