438 lines
11 KiB
C
438 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2013 Politecnico di Torino, Italy
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* TORSEC group -- http://security.polito.it
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*
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* Author: Roberto Sassu <roberto.sassu@polito.it>
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*
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* File: ima_template.c
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* Helpers to manage template descriptors.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/rculist.h>
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#include "ima.h"
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#include "ima_template_lib.h"
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enum header_fields { HDR_PCR, HDR_DIGEST, HDR_TEMPLATE_NAME,
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HDR_TEMPLATE_DATA, HDR__LAST };
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static struct ima_template_desc builtin_templates[] = {
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{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
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{.name = "ima-ng", .fmt = "d-ng|n-ng"},
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{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
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{.name = "ima-buf", .fmt = "d-ng|n-ng|buf"},
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{.name = "", .fmt = ""}, /* placeholder for a custom format */
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};
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static LIST_HEAD(defined_templates);
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static DEFINE_SPINLOCK(template_list);
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static const struct ima_template_field supported_fields[] = {
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{.field_id = "d", .field_init = ima_eventdigest_init,
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.field_show = ima_show_template_digest},
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{.field_id = "n", .field_init = ima_eventname_init,
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.field_show = ima_show_template_string},
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{.field_id = "d-ng", .field_init = ima_eventdigest_ng_init,
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.field_show = ima_show_template_digest_ng},
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{.field_id = "n-ng", .field_init = ima_eventname_ng_init,
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.field_show = ima_show_template_string},
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{.field_id = "sig", .field_init = ima_eventsig_init,
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.field_show = ima_show_template_sig},
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{.field_id = "buf", .field_init = ima_eventbuf_init,
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.field_show = ima_show_template_buf},
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};
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/*
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* Used when restoring measurements carried over from a kexec. 'd' and 'n' don't
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* need to be accounted for since they shouldn't be defined in the same template
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* description as 'd-ng' and 'n-ng' respectively.
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*/
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#define MAX_TEMPLATE_NAME_LEN sizeof("d-ng|n-ng|sig|buf")
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static struct ima_template_desc *ima_template;
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static int __init ima_template_setup(char *str)
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{
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struct ima_template_desc *template_desc;
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int template_len = strlen(str);
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if (ima_template)
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return 1;
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ima_init_template_list();
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/*
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* Verify that a template with the supplied name exists.
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* If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
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*/
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template_desc = lookup_template_desc(str);
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if (!template_desc) {
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pr_err("template %s not found, using %s\n",
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str, CONFIG_IMA_DEFAULT_TEMPLATE);
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return 1;
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}
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/*
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* Verify whether the current hash algorithm is supported
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* by the 'ima' template.
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*/
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if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
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ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
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pr_err("template does not support hash alg\n");
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return 1;
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}
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ima_template = template_desc;
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return 1;
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}
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__setup("ima_template=", ima_template_setup);
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static int __init ima_template_fmt_setup(char *str)
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{
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int num_templates = ARRAY_SIZE(builtin_templates);
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if (ima_template)
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return 1;
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if (template_desc_init_fields(str, NULL, NULL) < 0) {
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pr_err("format string '%s' not valid, using template %s\n",
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str, CONFIG_IMA_DEFAULT_TEMPLATE);
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return 1;
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}
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builtin_templates[num_templates - 1].fmt = str;
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ima_template = builtin_templates + num_templates - 1;
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return 1;
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}
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__setup("ima_template_fmt=", ima_template_fmt_setup);
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struct ima_template_desc *lookup_template_desc(const char *name)
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{
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struct ima_template_desc *template_desc;
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int found = 0;
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rcu_read_lock();
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list_for_each_entry_rcu(template_desc, &defined_templates, list) {
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if ((strcmp(template_desc->name, name) == 0) ||
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(strcmp(template_desc->fmt, name) == 0)) {
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found = 1;
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break;
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}
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}
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rcu_read_unlock();
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return found ? template_desc : NULL;
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}
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static const struct ima_template_field *
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lookup_template_field(const char *field_id)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
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if (strncmp(supported_fields[i].field_id, field_id,
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IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
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return &supported_fields[i];
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return NULL;
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}
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static int template_fmt_size(const char *template_fmt)
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{
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char c;
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int template_fmt_len = strlen(template_fmt);
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int i = 0, j = 0;
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while (i < template_fmt_len) {
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c = template_fmt[i];
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if (c == '|')
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j++;
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i++;
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}
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return j + 1;
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}
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int template_desc_init_fields(const char *template_fmt,
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const struct ima_template_field ***fields,
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int *num_fields)
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{
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const char *template_fmt_ptr;
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const struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX];
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int template_num_fields;
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int i, len;
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if (num_fields && *num_fields > 0) /* already initialized? */
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return 0;
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template_num_fields = template_fmt_size(template_fmt);
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if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
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pr_err("format string '%s' contains too many fields\n",
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template_fmt);
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return -EINVAL;
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}
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for (i = 0, template_fmt_ptr = template_fmt; i < template_num_fields;
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i++, template_fmt_ptr += len + 1) {
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char tmp_field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN + 1];
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len = strchrnul(template_fmt_ptr, '|') - template_fmt_ptr;
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if (len == 0 || len > IMA_TEMPLATE_FIELD_ID_MAX_LEN) {
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pr_err("Invalid field with length %d\n", len);
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return -EINVAL;
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}
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memcpy(tmp_field_id, template_fmt_ptr, len);
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tmp_field_id[len] = '\0';
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found_fields[i] = lookup_template_field(tmp_field_id);
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if (!found_fields[i]) {
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pr_err("field '%s' not found\n", tmp_field_id);
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return -ENOENT;
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}
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}
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if (fields && num_fields) {
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*fields = kmalloc_array(i, sizeof(*fields), GFP_KERNEL);
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if (*fields == NULL)
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return -ENOMEM;
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memcpy(*fields, found_fields, i * sizeof(*fields));
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*num_fields = i;
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}
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return 0;
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}
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void ima_init_template_list(void)
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{
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int i;
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if (!list_empty(&defined_templates))
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return;
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spin_lock(&template_list);
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for (i = 0; i < ARRAY_SIZE(builtin_templates); i++) {
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list_add_tail_rcu(&builtin_templates[i].list,
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&defined_templates);
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}
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spin_unlock(&template_list);
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}
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struct ima_template_desc *ima_template_desc_current(void)
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{
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if (!ima_template) {
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ima_init_template_list();
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ima_template =
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lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
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}
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return ima_template;
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}
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int __init ima_init_template(void)
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{
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struct ima_template_desc *template = ima_template_desc_current();
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int result;
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result = template_desc_init_fields(template->fmt,
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&(template->fields),
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&(template->num_fields));
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if (result < 0)
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pr_err("template %s init failed, result: %d\n",
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(strlen(template->name) ?
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template->name : template->fmt), result);
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return result;
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}
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static struct ima_template_desc *restore_template_fmt(char *template_name)
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{
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struct ima_template_desc *template_desc = NULL;
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int ret;
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ret = template_desc_init_fields(template_name, NULL, NULL);
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if (ret < 0) {
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pr_err("attempting to initialize the template \"%s\" failed\n",
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template_name);
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goto out;
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}
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template_desc = kzalloc(sizeof(*template_desc), GFP_KERNEL);
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if (!template_desc)
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goto out;
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template_desc->name = "";
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template_desc->fmt = kstrdup(template_name, GFP_KERNEL);
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if (!template_desc->fmt)
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goto out;
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spin_lock(&template_list);
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list_add_tail_rcu(&template_desc->list, &defined_templates);
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spin_unlock(&template_list);
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out:
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return template_desc;
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}
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static int ima_restore_template_data(struct ima_template_desc *template_desc,
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void *template_data,
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int template_data_size,
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struct ima_template_entry **entry)
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{
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int ret = 0;
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int i;
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*entry = kzalloc(sizeof(**entry) +
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template_desc->num_fields * sizeof(struct ima_field_data),
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GFP_NOFS);
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if (!*entry)
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return -ENOMEM;
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ret = ima_parse_buf(template_data, template_data + template_data_size,
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NULL, template_desc->num_fields,
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(*entry)->template_data, NULL, NULL,
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ENFORCE_FIELDS | ENFORCE_BUFEND, "template data");
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if (ret < 0) {
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kfree(*entry);
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return ret;
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}
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(*entry)->template_desc = template_desc;
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for (i = 0; i < template_desc->num_fields; i++) {
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struct ima_field_data *field_data = &(*entry)->template_data[i];
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u8 *data = field_data->data;
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(*entry)->template_data[i].data =
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kzalloc(field_data->len + 1, GFP_KERNEL);
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if (!(*entry)->template_data[i].data) {
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ret = -ENOMEM;
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break;
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}
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memcpy((*entry)->template_data[i].data, data, field_data->len);
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(*entry)->template_data_len += sizeof(field_data->len);
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(*entry)->template_data_len += field_data->len;
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}
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if (ret < 0) {
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ima_free_template_entry(*entry);
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*entry = NULL;
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}
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return ret;
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}
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/* Restore the serialized binary measurement list without extending PCRs. */
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int ima_restore_measurement_list(loff_t size, void *buf)
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{
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char template_name[MAX_TEMPLATE_NAME_LEN];
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struct ima_kexec_hdr *khdr = buf;
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struct ima_field_data hdr[HDR__LAST] = {
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[HDR_PCR] = {.len = sizeof(u32)},
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[HDR_DIGEST] = {.len = TPM_DIGEST_SIZE},
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};
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void *bufp = buf + sizeof(*khdr);
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void *bufendp;
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struct ima_template_entry *entry;
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struct ima_template_desc *template_desc;
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DECLARE_BITMAP(hdr_mask, HDR__LAST);
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unsigned long count = 0;
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int ret = 0;
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if (!buf || size < sizeof(*khdr))
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return 0;
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if (ima_canonical_fmt) {
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khdr->version = le16_to_cpu(khdr->version);
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khdr->count = le64_to_cpu(khdr->count);
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khdr->buffer_size = le64_to_cpu(khdr->buffer_size);
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}
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if (khdr->version != 1) {
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pr_err("attempting to restore a incompatible measurement list");
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return -EINVAL;
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}
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if (khdr->count > ULONG_MAX - 1) {
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pr_err("attempting to restore too many measurements");
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return -EINVAL;
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}
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bitmap_zero(hdr_mask, HDR__LAST);
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bitmap_set(hdr_mask, HDR_PCR, 1);
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bitmap_set(hdr_mask, HDR_DIGEST, 1);
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/*
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* ima kexec buffer prefix: version, buffer size, count
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* v1 format: pcr, digest, template-name-len, template-name,
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* template-data-size, template-data
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*/
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bufendp = buf + khdr->buffer_size;
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while ((bufp < bufendp) && (count++ < khdr->count)) {
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int enforce_mask = ENFORCE_FIELDS;
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enforce_mask |= (count == khdr->count) ? ENFORCE_BUFEND : 0;
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ret = ima_parse_buf(bufp, bufendp, &bufp, HDR__LAST, hdr, NULL,
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hdr_mask, enforce_mask, "entry header");
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if (ret < 0)
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break;
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if (hdr[HDR_TEMPLATE_NAME].len >= MAX_TEMPLATE_NAME_LEN) {
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pr_err("attempting to restore a template name that is too long\n");
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ret = -EINVAL;
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break;
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}
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/* template name is not null terminated */
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memcpy(template_name, hdr[HDR_TEMPLATE_NAME].data,
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hdr[HDR_TEMPLATE_NAME].len);
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template_name[hdr[HDR_TEMPLATE_NAME].len] = 0;
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if (strcmp(template_name, "ima") == 0) {
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pr_err("attempting to restore an unsupported template \"%s\" failed\n",
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template_name);
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ret = -EINVAL;
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break;
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}
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template_desc = lookup_template_desc(template_name);
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if (!template_desc) {
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template_desc = restore_template_fmt(template_name);
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if (!template_desc)
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break;
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}
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/*
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* Only the running system's template format is initialized
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* on boot. As needed, initialize the other template formats.
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*/
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ret = template_desc_init_fields(template_desc->fmt,
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&(template_desc->fields),
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&(template_desc->num_fields));
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if (ret < 0) {
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pr_err("attempting to restore the template fmt \"%s\" failed\n",
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template_desc->fmt);
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ret = -EINVAL;
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break;
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}
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ret = ima_restore_template_data(template_desc,
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hdr[HDR_TEMPLATE_DATA].data,
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hdr[HDR_TEMPLATE_DATA].len,
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&entry);
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if (ret < 0)
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break;
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memcpy(entry->digest, hdr[HDR_DIGEST].data,
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hdr[HDR_DIGEST].len);
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entry->pcr = !ima_canonical_fmt ? *(hdr[HDR_PCR].data) :
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le32_to_cpu(*(hdr[HDR_PCR].data));
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ret = ima_restore_measurement_entry(entry);
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if (ret < 0)
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break;
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}
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return ret;
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}
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