From: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> Subject: ima: on soft reboot, restore the measurement list The TPM PCRs are only reset on a hard reboot. In order to validate a TPM's quote after a soft reboot (eg. kexec -e), the IMA measurement list of the running kernel must be saved and restored on boot. This patch restores the measurement list. Link: http://lkml.kernel.org/r/1480554346-29071-3-git-send-email-zohar@xxxxxxxxxxxxxxxxxx Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> Acked-by: Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx> Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: Andreas Steffen <andreas.steffen@xxxxxxxxxxxxxx> Cc: Josh Sklar <sklar@xxxxxxxxxxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- security/integrity/ima/Makefile | 1 security/integrity/ima/ima.h | 21 ++ security/integrity/ima/ima_init.c | 2 security/integrity/ima/ima_kexec.c | 44 +++++ security/integrity/ima/ima_queue.c | 10 + security/integrity/ima/ima_template.c | 177 ++++++++++++++++++++++++ 6 files changed, 255 insertions(+) diff -puN security/integrity/ima/Makefile~ima-on-soft-reboot-restore-the-measurement-list security/integrity/ima/Makefile --- a/security/integrity/ima/Makefile~ima-on-soft-reboot-restore-the-measurement-list +++ a/security/integrity/ima/Makefile @@ -8,4 +8,5 @@ obj-$(CONFIG_IMA) += ima.o ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \ ima_policy.o ima_template.o ima_template_lib.o ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o +ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o diff -puN security/integrity/ima/ima.h~ima-on-soft-reboot-restore-the-measurement-list security/integrity/ima/ima.h --- a/security/integrity/ima/ima.h~ima-on-soft-reboot-restore-the-measurement-list +++ a/security/integrity/ima/ima.h @@ -28,6 +28,10 @@ #include "../integrity.h" +#ifdef CONFIG_HAVE_IMA_KEXEC +#include <asm/ima.h> +#endif + enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN, IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII }; enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 }; @@ -102,6 +106,21 @@ struct ima_queue_entry { }; extern struct list_head ima_measurements; /* list of all measurements */ +/* Some details preceding the binary serialized measurement list */ +struct ima_kexec_hdr { + u16 version; + u16 _reserved0; + u32 _reserved1; + u64 buffer_size; + u64 count; +}; + +#ifdef CONFIG_HAVE_IMA_KEXEC +void ima_load_kexec_buffer(void); +#else +static inline void ima_load_kexec_buffer(void) {} +#endif /* CONFIG_HAVE_IMA_KEXEC */ + /* Internal IMA function definitions */ int ima_init(void); int ima_fs_init(void); @@ -122,6 +141,8 @@ int ima_init_crypto(void); void ima_putc(struct seq_file *m, void *data, int datalen); void ima_print_digest(struct seq_file *m, u8 *digest, u32 size); struct ima_template_desc *ima_template_desc_current(void); +int ima_restore_measurement_entry(struct ima_template_entry *entry); +int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_init_template(void); /* diff -puN security/integrity/ima/ima_init.c~ima-on-soft-reboot-restore-the-measurement-list security/integrity/ima/ima_init.c --- a/security/integrity/ima/ima_init.c~ima-on-soft-reboot-restore-the-measurement-list +++ a/security/integrity/ima/ima_init.c @@ -129,6 +129,8 @@ int __init ima_init(void) if (rc != 0) return rc; + ima_load_kexec_buffer(); + rc = ima_add_boot_aggregate(); /* boot aggregate must be first entry */ if (rc != 0) return rc; diff -puN /dev/null security/integrity/ima/ima_kexec.c --- /dev/null +++ a/security/integrity/ima/ima_kexec.c @@ -0,0 +1,44 @@ +/* + * Copyright (C) 2016 IBM Corporation + * + * Authors: + * Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx> + * Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ +#include "ima.h" + +/* + * Restore the measurement list from the previous kernel. + */ +void ima_load_kexec_buffer(void) +{ + void *kexec_buffer = NULL; + size_t kexec_buffer_size = 0; + int rc; + + rc = ima_get_kexec_buffer(&kexec_buffer, &kexec_buffer_size); + switch (rc) { + case 0: + rc = ima_restore_measurement_list(kexec_buffer_size, + kexec_buffer); + if (rc != 0) + pr_err("Failed to restore the measurement list: %d\n", + rc); + + ima_free_kexec_buffer(); + break; + case -ENOTSUPP: + pr_debug("Restoring the measurement list not supported\n"); + break; + case -ENOENT: + pr_debug("No measurement list to restore\n"); + break; + default: + pr_debug("Error restoring the measurement list: %d\n", rc); + } +} diff -puN security/integrity/ima/ima_queue.c~ima-on-soft-reboot-restore-the-measurement-list security/integrity/ima/ima_queue.c --- a/security/integrity/ima/ima_queue.c~ima-on-soft-reboot-restore-the-measurement-list +++ a/security/integrity/ima/ima_queue.c @@ -149,3 +149,13 @@ out: op, audit_cause, result, audit_info); return result; } + +int ima_restore_measurement_entry(struct ima_template_entry *entry) +{ + int result = 0; + + mutex_lock(&ima_extend_list_mutex); + result = ima_add_digest_entry(entry); + mutex_unlock(&ima_extend_list_mutex); + return result; +} diff -puN security/integrity/ima/ima_template.c~ima-on-soft-reboot-restore-the-measurement-list security/integrity/ima/ima_template.c --- a/security/integrity/ima/ima_template.c~ima-on-soft-reboot-restore-the-measurement-list +++ a/security/integrity/ima/ima_template.c @@ -37,6 +37,7 @@ static struct ima_template_field support {.field_id = "sig", .field_init = ima_eventsig_init, .field_show = ima_show_template_sig}, }; +#define MAX_TEMPLATE_NAME_LEN 15 static struct ima_template_desc *ima_template; static struct ima_template_desc *lookup_template_desc(const char *name); @@ -205,3 +206,179 @@ int __init ima_init_template(void) return result; } + +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 binary_field_data { + u32 len; + u8 data[0]; + } __packed; + + struct binary_field_data *field_data; + int offset = 0; + int ret = 0; + int i; + + *entry = kzalloc(sizeof(**entry) + + template_desc->num_fields * sizeof(struct ima_field_data), + GFP_NOFS); + if (!*entry) + return -ENOMEM; + + (*entry)->template_desc = template_desc; + for (i = 0; i < template_desc->num_fields; i++) { + field_data = template_data + offset; + + /* Each field of the template data is prefixed with a length. */ + if (offset > (template_data_size - sizeof(*field_data))) { + pr_err("Restoring the template field failed\n"); + ret = -EINVAL; + break; + } + offset += sizeof(*field_data); + + if (offset > (template_data_size - field_data->len)) { + pr_err("Restoring the template field data failed\n"); + ret = -EINVAL; + break; + } + offset += field_data->len; + + (*entry)->template_data[i].len = field_data->len; + (*entry)->template_data_len += sizeof(field_data->len); + + (*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, field_data->data, + 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) +{ + struct binary_hdr_v1 { + u32 pcr; + u8 digest[TPM_DIGEST_SIZE]; + u32 template_name_len; + char template_name[0]; + } __packed; + char template_name[MAX_TEMPLATE_NAME_LEN]; + + struct binary_data_v1 { + u32 template_data_size; + char template_data[0]; + } __packed; + + struct ima_kexec_hdr *khdr = buf; + struct binary_hdr_v1 *hdr_v1; + struct binary_data_v1 *data_v1; + + void *bufp = buf + sizeof(*khdr); + void *bufendp = buf + khdr->buffer_size; + struct ima_template_entry *entry; + struct ima_template_desc *template_desc; + unsigned long count = 0; + int ret = 0; + + if (!buf || size < sizeof(*khdr)) + return 0; + + 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; + } + + /* + * ima kexec buffer prefix: version, buffer size, count + * v1 format: pcr, digest, template-name-len, template-name, + * template-data-size, template-data + */ + while ((bufp < bufendp) && (count++ < khdr->count)) { + hdr_v1 = bufp; + if (bufp > (bufendp - sizeof(*hdr_v1))) { + pr_err("attempting to restore partial measurement\n"); + ret = -EINVAL; + break; + } + bufp += sizeof(*hdr_v1); + + if ((hdr_v1->template_name_len >= MAX_TEMPLATE_NAME_LEN) || + (bufp > (bufendp - hdr_v1->template_name_len))) { + pr_err("attempting to restore a template name \ + that is too long\n"); + ret = -EINVAL; + break; + } + data_v1 = bufp += (u_int8_t)hdr_v1->template_name_len; + + /* template name is not null terminated */ + memcpy(template_name, hdr_v1->template_name, + hdr_v1->template_name_len); + template_name[hdr_v1->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; + } + + /* get template format */ + template_desc = lookup_template_desc(template_name); + if (!template_desc) { + pr_err("template \"%s\" not found\n", template_name); + ret = -EINVAL; + break; + } + + if (bufp > (bufendp - sizeof(data_v1->template_data_size))) { + pr_err("restoring the template data size failed\n"); + ret = -EINVAL; + break; + } + bufp += (u_int8_t) sizeof(data_v1->template_data_size); + + if (bufp > (bufendp - data_v1->template_data_size)) { + pr_err("restoring the template data failed\n"); + ret = -EINVAL; + break; + } + bufp += data_v1->template_data_size; + + ret = ima_restore_template_data(template_desc, + data_v1->template_data, + data_v1->template_data_size, + &entry); + if (ret < 0) + break; + + memcpy(entry->digest, hdr_v1->digest, TPM_DIGEST_SIZE); + entry->pcr = hdr_v1->pcr; + ret = ima_restore_measurement_entry(entry); + if (ret < 0) + break; + + } + return ret; +} _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
