diff options
Diffstat (limited to 'lib/libsecureboot/vepcr.c')
| -rw-r--r-- | lib/libsecureboot/vepcr.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/lib/libsecureboot/vepcr.c b/lib/libsecureboot/vepcr.c new file mode 100644 index 000000000000..f4f146975e5e --- /dev/null +++ b/lib/libsecureboot/vepcr.c @@ -0,0 +1,167 @@ +/*- + * 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> +#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; +} |