security/integrity/ima/ima_template.c

   1 /*
   2  * Copyright (C) 2013 Politecnico di Torino, Italy
   3  *                    TORSEC group -- http://security.polito.it
   4  *
   5  * Author: Roberto Sassu <roberto.sassu@polito.it>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation, version 2 of the
  10  * License.
  11  *
  12  * File: ima_template.c
  13  *      Helpers to manage template descriptors.
  14  */
  15 #include "ima.h"
  16 #include "ima_template_lib.h"
  17
  18 static struct ima_template_desc defined_templates[] = {
  19         {.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
  20         {.name = "ima-ng",.fmt = "d-ng|n-ng"},
  21 };
  22
  23 static struct ima_template_field supported_fields[] = {
  24         {.field_id = "d",.field_init = ima_eventdigest_init,
  25          .field_show = ima_show_template_digest},
  26         {.field_id = "n",.field_init = ima_eventname_init,
  27          .field_show = ima_show_template_string},
  28         {.field_id = "d-ng",.field_init = ima_eventdigest_ng_init,
  29          .field_show = ima_show_template_digest_ng},
  30         {.field_id = "n-ng",.field_init = ima_eventname_ng_init,
  31          .field_show = ima_show_template_string},
  32 };
  33
  34 static struct ima_template_desc *ima_template;
  35
  36 static struct ima_template_desc *lookup_template_desc(const char *name)
  37 {
  38         int i;
  39
  40         for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
  41                 if (strcmp(defined_templates[i].name, name) == 0)
  42                         return defined_templates + i;
  43         }
  44
  45         return NULL;
  46 }
  47
  48 static struct ima_template_field *lookup_template_field(const char *field_id)
  49 {
  50         int i;
  51
  52         for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
  53                 if (strncmp(supported_fields[i].field_id, field_id,
  54                             IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
  55                         return &supported_fields[i];
  56         return NULL;
  57 }
  58
  59 static int template_fmt_size(char *template_fmt)
  60 {
  61         char c;
  62         int template_fmt_len = strlen(template_fmt);
  63         int i = 0, j = 0;
  64
  65         while (i < template_fmt_len) {
  66                 c = template_fmt[i];
  67                 if (c == '|')
  68                         j++;
  69                 i++;
  70         }
  71
  72         return j + 1;
  73 }
  74
  75 static int template_desc_init_fields(char *template_fmt,
  76                                      struct ima_template_field ***fields,
  77                                      int *num_fields)
  78 {
  79         char *c, *template_fmt_ptr = template_fmt;
  80         int template_num_fields = template_fmt_size(template_fmt);
  81         int i, result = 0;
  82
  83         if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX)
  84                 return -EINVAL;
  85
  86         *fields = kzalloc(template_num_fields * sizeof(*fields), GFP_KERNEL);
  87         if (*fields == NULL) {
  88                 result = -ENOMEM;
  89                 goto out;
  90         }
  91         for (i = 0; (c = strsep(&template_fmt_ptr, "|")) != NULL &&
  92              i < template_num_fields; i++) {
  93                 struct ima_template_field *f = lookup_template_field(c);
  94
  95                 if (!f) {
  96                         result = -ENOENT;
  97                         goto out;
  98                 }
  99                 (*fields)[i] = f;
 100         }
 101         *num_fields = i;
 102         return 0;
 103 out:
 104         kfree(*fields);
 105         *fields = NULL;
 106         return result;
 107 }
 108
 109 static int init_defined_templates(void)
 110 {
 111         int i = 0;
 112         int result = 0;
 113
 114         /* Init defined templates. */
 115         for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
 116                 struct ima_template_desc *template = &defined_templates[i];
 117
 118                 result = template_desc_init_fields(template->fmt,
 119                                                    &(template->fields),
 120                                                    &(template->num_fields));
 121                 if (result < 0)
 122                         return result;
 123         }
 124         return result;
 125 }
 126
 127 struct ima_template_desc *ima_template_desc_current(void)
 128 {
 129         if (!ima_template)
 130                 ima_template = lookup_template_desc(IMA_TEMPLATE_IMA_NAME);
 131
 132         return ima_template;
 133 }
 134
 135 int ima_init_template(void)
 136 {
 137         int result;
 138
 139         result = init_defined_templates();
 140         if (result < 0)
 141                 return result;
 142
 143         return 0;
 144 }