// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2013 Politecnico di Torino, Italy
* TORSEC group -- https://security.polito.it
*
* Author: Roberto Sassu <[email protected]>
*
* File: ima_template.c
* Helpers to manage template descriptors.
*/
#include <linux/rculist.h>
#include "ima.h"
#include "ima_template_lib.h"
enum header_fields { HDR_PCR, HDR_DIGEST, HDR_TEMPLATE_NAME,
HDR_TEMPLATE_DATA, HDR__LAST };
static struct ima_template_desc builtin_templates[] = {
{.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
{.name = "ima-ng", .fmt = "d-ng|n-ng"},
{.name = "ima-sig", .fmt = "d-ng|n-ng|sig"},
{.name = "ima-ngv2", .fmt = "d-ngv2|n-ng"},
{.name = "ima-sigv2", .fmt = "d-ngv2|n-ng|sig"},
{.name = "ima-buf", .fmt = "d-ng|n-ng|buf"},
{.name = "ima-modsig", .fmt = "d-ng|n-ng|sig|d-modsig|modsig"},
{.name = "evm-sig",
.fmt = "d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode"},
{.name = "", .fmt = ""}, /* placeholder for a custom format */
};
static LIST_HEAD(defined_templates);
static DEFINE_SPINLOCK(template_list);
static int template_setup_done;
static const struct ima_template_field supported_fields[] = {
{.field_id = "d", .field_init = ima_eventdigest_init,
.field_show = ima_show_template_digest},
{.field_id = "n", .field_init = ima_eventname_init,
.field_show = ima_show_template_string},
{.field_id = "d-ng", .field_init = ima_eventdigest_ng_init,
.field_show = ima_show_template_digest_ng},
{.field_id = "d-ngv2", .field_init = ima_eventdigest_ngv2_init,
.field_show = ima_show_template_digest_ngv2},
{.field_id = "n-ng", .field_init = ima_eventname_ng_init,
.field_show = ima_show_template_string},
{.field_id = "sig", .field_init = ima_eventsig_init,
.field_show = ima_show_template_sig},
{.field_id = "buf", .field_init = ima_eventbuf_init,
.field_show = ima_show_template_buf},
{.field_id = "d-modsig", .field_init = ima_eventdigest_modsig_init,
.field_show = ima_show_template_digest_ng},
{.field_id = "modsig", .field_init = ima_eventmodsig_init,
.field_show = ima_show_template_sig},
{.field_id = "evmsig", .field_init = ima_eventevmsig_init,
.field_show = ima_show_template_sig},
{.field_id = "iuid", .field_init = ima_eventinodeuid_init,
.field_show = ima_show_template_uint},
{.field_id = "igid", .field_init = ima_eventinodegid_init,
.field_show = ima_show_template_uint},
{.field_id = "imode", .field_init = ima_eventinodemode_init,
.field_show = ima_show_template_uint},
{.field_id = "xattrnames",
.field_init = ima_eventinodexattrnames_init,
.field_show = ima_show_template_string},
{.field_id = "xattrlengths",
.field_init = ima_eventinodexattrlengths_init,
.field_show = ima_show_template_sig},
{.field_id = "xattrvalues",
.field_init = ima_eventinodexattrvalues_init,
.field_show = ima_show_template_sig},
};
/*
* Used when restoring measurements carried over from a kexec. 'd' and 'n' don't
* need to be accounted for since they shouldn't be defined in the same template
* description as 'd-ng' and 'n-ng' respectively.
*/
#define MAX_TEMPLATE_NAME_LEN \
sizeof("d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode")
static struct ima_template_desc *ima_template;
static struct ima_template_desc *ima_buf_template;
/**
* ima_template_has_modsig - Check whether template has modsig-related fields.
* @ima_template: IMA template to check.
*
* Tells whether the given template has fields referencing a file's appended
* signature.
*/
bool ima_template_has_modsig(const struct ima_template_desc *ima_template)
{
int i;
for (i = 0; i < ima_template->num_fields; i++)
if (!strcmp(ima_template->fields[i]->field_id, "modsig") ||
!strcmp(ima_template->fields[i]->field_id, "d-modsig"))
return true;
return false;
}
static int __init ima_template_setup(char *str)
{
struct ima_template_desc *template_desc;
int template_len = strlen(str);
if (template_setup_done)
return 1;
if (!ima_template)
ima_init_template_list();
/*
* Verify that a template with the supplied name exists.
* If not, use CONFIG_IMA_DEFAULT_TEMPLATE.
*/
template_desc = lookup_template_desc(str);
if (!template_desc) {
pr_err("template %s not found, using %s\n",
str, CONFIG_IMA_DEFAULT_TEMPLATE);
return 1;
}
/*
* Verify whether the current hash algorithm is supported
* by the 'ima' template.
*/
if (template_len == 3 && strcmp(str, IMA_TEMPLATE_IMA_NAME) == 0 &&
ima_hash_algo != HASH_ALGO_SHA1 && ima_hash_algo != HASH_ALGO_MD5) {
pr_err("template does not support hash alg\n");
return 1;
}
ima_template = template_desc;
template_setup_done = 1;
return 1;
}
__setup("ima_template=", ima_template_setup);
static int __init ima_template_fmt_setup(char *str)
{
int num_templates = ARRAY_SIZE(builtin_templates);
if (template_setup_done)
return 1;
if (template_desc_init_fields(str, NULL, NULL) < 0) {
pr_err("format string '%s' not valid, using template %s\n",
str, CONFIG_IMA_DEFAULT_TEMPLATE);
return 1;
}
builtin_templates[num_templates - 1].fmt = str;
ima_template = builtin_templates + num_templates - 1;
template_setup_done = 1;
return 1;
}
__setup("ima_template_fmt=", ima_template_fmt_setup);
struct ima_template_desc *lookup_template_desc(const char *name)
{
struct ima_template_desc *template_desc;
int found = 0;
rcu_read_lock();
list_for_each_entry_rcu(template_desc, &defined_templates, list) {
if ((strcmp(template_desc->name, name) == 0) ||
(strcmp(template_desc->fmt, name) == 0)) {
found = 1;
break;
}
}
rcu_read_unlock();
return found ? template_desc : NULL;
}
static const struct ima_template_field *
lookup_template_field(const char *field_id)
{
int i;
for (i = 0; i < ARRAY_SIZE(supported_fields); i++)
if (strncmp(supported_fields[i].field_id, field_id,
IMA_TEMPLATE_FIELD_ID_MAX_LEN) == 0)
return &supported_fields[i];
return NULL;
}
static int template_fmt_size(const char *template_fmt)
{
char c;
int template_fmt_len = strlen(template_fmt);
int i = 0, j = 0;
while (i < template_fmt_len) {
c = template_fmt[i];
if (c == '|')
j++;
i++;
}
return j + 1;
}
int template_desc_init_fields(const char *template_fmt,
const struct ima_template_field ***fields,
int *num_fields)
{
const char *template_fmt_ptr;
const struct ima_template_field *found_fields[IMA_TEMPLATE_NUM_FIELDS_MAX];
int template_num_fields;
int i, len;
if (num_fields && *num_fields > 0) /* already initialized? */
return 0;
template_num_fields = template_fmt_size(template_fmt);
if (template_num_fields > IMA_TEMPLATE_NUM_FIELDS_MAX) {
pr_err("format string '%s' contains too many fields\n",
template_fmt);
return -EINVAL;
}
for (i = 0, template_fmt_ptr = template_fmt; i < template_num_fields;
i++, template_fmt_ptr += len + 1) {
char tmp_field_id[IMA_TEMPLATE_FIELD_ID_MAX_LEN + 1];
len = strchrnul(template_fmt_ptr, '|') - template_fmt_ptr;
if (len == 0 || len > IMA_TEMPLATE_FIELD_ID_MAX_LEN) {
pr_err("Invalid field with length %d\n", len);
return -EINVAL;
}
memcpy(tmp_field_id, template_fmt_ptr, len);
tmp_field_id[len] = '\0';
found_fields[i] = lookup_template_field(tmp_field_id);
if (!found_fields[i]) {
pr_err("field '%s' not found\n", tmp_field_id);
return -ENOENT;
}
}
if (fields && num_fields) {
*fields = kmalloc_array(i, sizeof(**fields), GFP_KERNEL);
if (*fields == NULL)
return -ENOMEM;
memcpy(*fields, found_fields, i * sizeof(**fields));
*num_fields = i;
}
return 0;
}
void ima_init_template_list(void)
{
int i;
if (!list_empty(&defined_templates))
return;
spin_lock(&template_list);
for (i = 0; i < ARRAY_SIZE(builtin_templates); i++) {
list_add_tail_rcu(&builtin_templates[i].list,
&defined_templates);
}
spin_unlock(&template_list);
}
struct ima_template_desc *ima_template_desc_current(void)
{
if (!ima_template) {
ima_init_template_list();
ima_template =
lookup_template_desc(CONFIG_IMA_DEFAULT_TEMPLATE);
}
return ima_template;
}
struct ima_template_desc *ima_template_desc_buf(void)
{
if (!ima_buf_template) {
ima_init_template_list();
ima_buf_template = lookup_template_desc("ima-buf");
}
return ima_buf_template;
}
int __init ima_init_template(void)
{
struct ima_template_desc *template = ima_template_desc_current();
int result;
result = template_desc_init_fields(template->fmt,
&(template->fields),
&(template->num_fields));
if (result < 0) {
pr_err("template %s init failed, result: %d\n",
(strlen(template->name) ?
template->name : template->fmt), result);
return result;
}
template = ima_template_desc_buf();
if (!template) {
pr_err("Failed to get ima-buf template\n");
return -EINVAL;
}
result = template_desc_init_fields(template->fmt,
&(template->fields),
&(template->num_fields));
if (result < 0)
pr_err("template %s init failed, result: %d\n",
(strlen(template->name) ?
template->name : template->fmt), result);
return result;
}
static struct ima_template_desc *restore_template_fmt(char *template_name)
{
struct ima_template_desc *template_desc = NULL;
int ret;
ret = template_desc_init_fields(template_name, NULL, NULL);
if (ret < 0) {
pr_err("attempting to initialize the template \"%s\" failed\n",
template_name);
goto out;
}
template_desc = kzalloc(sizeof(*template_desc), GFP_KERNEL);
if (!template_desc)
goto out;
template_desc->name = "";
template_desc->fmt = kstrdup(template_name, GFP_KERNEL);
if (!template_desc->fmt) {
kfree(template_desc);
template_desc = NULL;
goto out;
}
spin_lock(&template_list);
list_add_tail_rcu(&template_desc->list, &defined_templates);
spin_unlock(&template_list);
out:
return template_desc;
}
static int ima_restore_template_data(struct ima_template_desc *template_desc,
void *template_data,
int template_data_size,
struct ima_template_entry **entry)
{
struct tpm_digest *digests;
int ret = 0;
int i;
*entry = kzalloc(struct_size(*entry, template_data,
template_desc->num_fields), GFP_NOFS);
if (!*entry)
return -ENOMEM;
digests = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots,
sizeof(*digests), GFP_NOFS);
if (!digests) {
kfree(*entry);
return -ENOMEM;
}
(*entry)->digests = digests;
ret = ima_parse_buf(template_data, template_data + template_data_size,
NULL, template_desc->num_fields,
(*entry)->template_data, NULL, NULL,
ENFORCE_FIELDS | ENFORCE_BUFEND, "template data");
if (ret < 0) {
kfree((*entry)->digests);
kfree(*entry);
return ret;
}
(*entry)->template_desc = template_desc;
for (i = 0; i < template_desc->num_fields; i++) {
struct ima_field_data *field_data = &(*entry)->template_data[i];
u8 *data = field_data->data;
(*entry)->template_data[i].data =
kzalloc(field_data->len + 1, GFP_KERNEL);
if (!(*entry)->template_data[i].data) {
ret = -ENOMEM;
break;
}
memcpy((*entry)->template_data[i].data, data, field_data->len);
(*entry)->template_data_len += sizeof(field_data->len);
(*entry)->template_data_len += field_data->len;
}
if (ret < 0) {
ima_free_template_entry(*entry);
*entry = NULL;
}
return ret;
}
/* Restore the serialized binary measurement list without extending PCRs. */
int ima_restore_measurement_list(loff_t size, void *buf)
{
char template_name[MAX_TEMPLATE_NAME_LEN];
unsigned char zero[TPM_DIGEST_SIZE] = { 0 };
struct ima_kexec_hdr *khdr = buf;
struct ima_field_data hdr[HDR__LAST] = {
[HDR_PCR] = {.len = sizeof(u32)},
[HDR_DIGEST] = {.len = TPM_DIGEST_SIZE},
};
void *bufp = buf + sizeof(*khdr);
void *bufendp;
struct ima_template_entry *entry;
struct ima_template_desc *template_desc;
DECLARE_BITMAP(hdr_mask, HDR__LAST);
unsigned long count = 0;
int ret = 0;
if (!buf || size < sizeof(*khdr))
return 0;
if (ima_canonical_fmt) {
khdr->version = le16_to_cpu((__force __le16)khdr->version);
khdr->count = le64_to_cpu((__force __le64)khdr->count);
khdr->buffer_size = le64_to_cpu((__force __le64)khdr->buffer_size);
}
if (khdr->version != 1) {
pr_err("attempting to restore a incompatible measurement list");
return -EINVAL;
}
if (khdr->count > ULONG_MAX - 1) {
pr_err("attempting to restore too many measurements");
return -EINVAL;
}
bitmap_zero(hdr_mask, HDR__LAST);
bitmap_set(hdr_mask, HDR_PCR, 1);
bitmap_set(hdr_mask, HDR_DIGEST, 1);
/*
* ima kexec buffer prefix: version, buffer size, count
* v1 format: pcr, digest, template-name-len, template-name,
* template-data-size, template-data
*/
bufendp = buf + khdr->buffer_size;
while ((bufp < bufendp) && (count++ < khdr->count)) {
int enforce_mask = ENFORCE_FIELDS;
enforce_mask |= (count == khdr->count) ? ENFORCE_BUFEND : 0;
ret = ima_parse_buf(bufp, bufendp, &bufp, HDR__LAST, hdr, NULL,
hdr_mask, enforce_mask, "entry header");
if (ret < 0)
break;
if (hdr[HDR_TEMPLATE_NAME].len >= MAX_TEMPLATE_NAME_LEN) {
pr_err("attempting to restore a template name that is too long\n");
ret = -EINVAL;
break;
}
/* template name is not null terminated */
memcpy(template_name, hdr[HDR_TEMPLATE_NAME].data,
hdr[HDR_TEMPLATE_NAME].len);
template_name[hdr[HDR_TEMPLATE_NAME].len] = 0;
if (strcmp(template_name, "ima") == 0) {
pr_err("attempting to restore an unsupported template \"%s\" failed\n",
template_name);
ret = -EINVAL;
break;
}
template_desc = lookup_template_desc(template_name);
if (!template_desc) {
template_desc = restore_template_fmt(template_name);
if (!template_desc)
break;
}
/*
* Only the running system's template format is initialized
* on boot. As needed, initialize the other template formats.
*/
ret = template_desc_init_fields(template_desc->fmt,
&(template_desc->fields),
&(template_desc->num_fields));
if (ret < 0) {
pr_err("attempting to restore the template fmt \"%s\" failed\n",
template_desc->fmt);
ret = -EINVAL;
break;
}
ret = ima_restore_template_data(template_desc,
hdr[HDR_TEMPLATE_DATA].data,
hdr[HDR_TEMPLATE_DATA].len,
&entry);
if (ret < 0)
break;
if (memcmp(hdr[HDR_DIGEST].data, zero, sizeof(zero))) {
ret = ima_calc_field_array_hash(
&entry->template_data[0],
entry);
if (ret < 0) {
pr_err("cannot calculate template digest\n");
ret = -EINVAL;
break;
}
}
entry->pcr = !ima_canonical_fmt ? *(u32 *)(hdr[HDR_PCR].data) :
le32_to_cpu(*(__le32 *)(hdr[HDR_PCR].data));
ret = ima_restore_measurement_entry(entry);
if (ret < 0)
break;
}
return ret;
}
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