security/apparmor/lib.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains basic common functions used in AppArmor
   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/mm.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18 #include <linux/vmalloc.h>
  19
  20 #include "include/audit.h"
  21
  22
  23 /**
  24  * aa_split_fqname - split a fqname into a profile and namespace name
  25  * @fqname: a full qualified name in namespace profile format (NOT NULL)
  26  * @ns_name: pointer to portion of the string containing the ns name (NOT NULL)
  27  *
  28  * Returns: profile name or NULL if one is not specified
  29  *
  30  * Split a namespace name from a profile name (see policy.c for naming
  31  * description).  If a portion of the name is missing it returns NULL for
  32  * that portion.
  33  *
  34  * NOTE: may modify the @fqname string.  The pointers returned point
  35  *       into the @fqname string.
  36  */
  37 char *aa_split_fqname(char *fqname, char **ns_name)
  38 {
  39         char *name = strim(fqname);
  40
  41         *ns_name = NULL;
  42         if (name[0] == ':') {
  43                 char *split = strchr(&name[1], ':');
  44                 *ns_name = skip_spaces(&name[1]);
  45                 if (split) {
  46                         /* overwrite ':' with \0 */
  47                         *split = 0;
  48                         name = skip_spaces(split + 1);
  49                 } else
  50                         /* a ns name without a following profile is allowed */
  51                         name = NULL;
  52         }
  53         if (name && *name == 0)
  54                 name = NULL;
  55
  56         return name;
  57 }
  58
  59 /**
  60  * aa_info_message - log a none profile related status message
  61  * @str: message to log
  62  */
  63 void aa_info_message(const char *str)
  64 {
  65         if (audit_enabled) {
  66                 struct common_audit_data sa;
  67                 COMMON_AUDIT_DATA_INIT(&sa, NONE);
  68                 sa.aad.info = str;
  69                 aa_audit_msg(AUDIT_APPARMOR_STATUS, &sa, NULL);
  70         }
  71         printk(KERN_INFO "AppArmor: %s\n", str);
  72 }
  73
  74 /**
  75  * kvmalloc - do allocation preferring kmalloc but falling back to vmalloc
  76  * @size: size of allocation
  77  *
  78  * Return: allocated buffer or NULL if failed
  79  *
  80  * It is possible that policy being loaded from the user is larger than
  81  * what can be allocated by kmalloc, in those cases fall back to vmalloc.
  82  */
  83 void *kvmalloc(size_t size)
  84 {
  85         void *buffer = NULL;
  86
  87         if (size == 0)
  88                 return NULL;
  89
  90         /* do not attempt kmalloc if we need more than 16 pages at once */
  91         if (size <= (16*PAGE_SIZE))
  92                 buffer = kmalloc(size, GFP_NOIO | __GFP_NOWARN);
  93         if (!buffer) {
  94                 /* see kvfree for why size must be at least work_struct size
  95                  * when allocated via vmalloc
  96                  */
  97                 if (size < sizeof(struct work_struct))
  98                         size = sizeof(struct work_struct);
  99                 buffer = vmalloc(size);
 100         }
 101         return buffer;
 102 }
 103
 104 /**
 105  * do_vfree - workqueue routine for freeing vmalloced memory
 106  * @work: data to be freed
 107  *
 108  * The work_struct is overlaid to the data being freed, as at the point
 109  * the work is scheduled the data is no longer valid, be its freeing
 110  * needs to be delayed until safe.
 111  */
 112 static void do_vfree(struct work_struct *work)
 113 {
 114         vfree(work);
 115 }
 116
 117 /**
 118  * kvfree - free an allocation do by kvmalloc
 119  * @buffer: buffer to free (MAYBE_NULL)
 120  *
 121  * Free a buffer allocated by kvmalloc
 122  */
 123 void kvfree(void *buffer)
 124 {
 125         if (is_vmalloc_addr(buffer)) {
 126                 /* Data is no longer valid so just use the allocated space
 127                  * as the work_struct
 128                  */
 129                 struct work_struct *work = (struct work_struct *) buffer;
 130                 INIT_WORK(work, do_vfree);
 131                 schedule_work(work);
 132         } else
 133                 kfree(buffer);
 134 }