freebsd-src/lib/libsecureboot/vepcr.c
Simon J. Gerraty 53f151f906 Fix pkgfs stat so it satisfies libsecureboot
We need a valid st_dev, st_ino and st_mtime
to correctly track which files have been verified
and to update our notion of time.

ve_utc_set(): ignore utc if it would jump our current time
by more than VE_UTC_MAX_JUMP (20 years).

Allow testing of install command via userboot.
Need to fix its stat implementation too.

bhyveload also needs stat fixed - due to change to userboot.h

Call ve_error_get() from vectx_close() when hash is wrong.

Track the names of files we have hashed into pcr

For the purposes of measured boot, it is important
to be able to reproduce the hash reflected in
loader.ve.pcr
so loader.ve.hashed provides a list of names in the order they
were added.

Reviewed by:	imp
MFC after:	1 week
Sponsored by:	Juniper Networks
Differential Revision:	https://reviews.freebsd.org//D24027
2020-03-25 19:12:19 +00:00

170 lines
4.1 KiB
C

/*-
* Copyright (c) 2018, Juniper Networks, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/queue.h>
#include "libsecureboot-priv.h"
/*
* To support measured boot without putting a ton
* of extra code in the loader, we just maintain
* a hash of all the hashes we (attempt to) verify.
* The loader can export this for kernel or rc script
* to feed to a TPM pcr register - hence the name ve_pcr.
*
* NOTE: in the current standard the TPM pcr register size is for SHA1,
* the fact that we provide a SHA256 hash should not matter
* as long as we are consistent - it can be truncated or hashed
* before feeding to TPM.
*/
static const br_hash_class *pcr_md = NULL;
static br_hash_compat_context pcr_ctx;
static size_t pcr_hlen = 0;
static int pcr_updating = -1;
struct hashed_info {
const char *hi_path;
const char *hi_basename;
STAILQ_ENTRY(hashed_info) entries;
};
static STAILQ_HEAD(, hashed_info) hi_list;
/**
* @brief initialize pcr context
*
* Real TPM registers only hold a SHA1 hash
* but we use SHA256
*/
void
ve_pcr_init(void)
{
if (pcr_updating < 0) {
pcr_updating = 0;
pcr_hlen = br_sha256_SIZE;
pcr_md = &br_sha256_vtable;
pcr_md->init(&pcr_ctx.vtable);
STAILQ_INIT(&hi_list);
}
}
/**
* @brief get pcr_updating state
*/
int
ve_pcr_updating_get(void)
{
return (pcr_updating);
}
/**
* @brief set pcr_updating state
*/
void
ve_pcr_updating_set(int updating)
{
pcr_updating = updating;
}
/**
* @brief update pcr context
*/
void
ve_pcr_update(const char *path, unsigned char *data, size_t dlen)
{
struct hashed_info *hip;
if (pcr_updating > 0 && pcr_md != NULL) {
pcr_md->update(&pcr_ctx.vtable, data, dlen);
/* if mallocs fail, measured boot will likely fail too */
if ((hip = malloc(sizeof(struct hashed_info)))) {
hip->hi_path = strdup(path);
if (!hip->hi_path) {
free(hip);
return;
}
hip->hi_basename = strrchr(hip->hi_path, '/');
if (hip->hi_basename) {
hip->hi_basename++;
} else {
hip->hi_basename = hip->hi_path;
}
STAILQ_INSERT_TAIL(&hi_list, hip, entries);
}
}
}
/**
* @brief get pcr result
*/
ssize_t
ve_pcr_get(unsigned char *buf, size_t sz)
{
if (!pcr_md)
return (-1);
if (sz < pcr_hlen)
return (-1);
pcr_md->out(&pcr_ctx.vtable, buf);
return (pcr_hlen);
}
/**
* @brief get list of paths in prc
*/
char *
ve_pcr_hashed_get(int flags)
{
const char *cp;
char *hinfo;
struct hashed_info *hip;
size_t nbytes;
size_t x;
int n;
n = 0;
nbytes = x = 0;
hinfo = NULL;
STAILQ_FOREACH(hip, &hi_list, entries) {
nbytes += 1 + strlen(flags ? hip->hi_basename : hip->hi_path);
}
if (nbytes > 1) {
hinfo = malloc(nbytes + 2);
if (hinfo) {
STAILQ_FOREACH(hip, &hi_list, entries) {
cp = flags ? hip->hi_basename : hip->hi_path;
n = snprintf(&hinfo[x], nbytes - x, "%s,", cp);
x += n;
}
if (x > 0) {
hinfo[x-1] = '\0';
}
}
}
return hinfo;
}