// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2013 Politecnico di Torino, Italy * TORSEC group -- https://security.polito.it * * Author: Roberto Sassu <roberto.sassu@polito.it> * * 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; }