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-rw-r--r--src/journal/journal-authenticate.c434
1 files changed, 434 insertions, 0 deletions
diff --git a/src/journal/journal-authenticate.c b/src/journal/journal-authenticate.c
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+++ b/src/journal/journal-authenticate.c
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+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2012 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include "journal-def.h"
+#include "journal-file.h"
+#include "journal-authenticate.h"
+#include "fsprg.h"
+
+static void *fsprg_state(JournalFile *f) {
+ uint64_t a, b;
+ assert(f);
+
+ if (!f->authenticate)
+ return NULL;
+
+ a = le64toh(f->fsprg_header->header_size);
+ b = le64toh(f->fsprg_header->state_size);
+
+ if (a + b > f->fsprg_size)
+ return NULL;
+
+ return (uint8_t*) f->fsprg_header + a;
+}
+
+static uint64_t journal_file_tag_seqnum(JournalFile *f) {
+ uint64_t r;
+
+ assert(f);
+
+ r = le64toh(f->header->n_tags) + 1;
+ f->header->n_tags = htole64(r);
+
+ return r;
+}
+
+int journal_file_append_tag(JournalFile *f) {
+ Object *o;
+ uint64_t p;
+ int r;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ if (!f->hmac_running)
+ return 0;
+
+ log_debug("Writing tag for epoch %llu\n", (unsigned long long) FSPRG_GetEpoch(fsprg_state(f)));
+
+ assert(f->hmac);
+
+ r = journal_file_append_object(f, OBJECT_TAG, sizeof(struct TagObject), &o, &p);
+ if (r < 0)
+ return r;
+
+ o->tag.seqnum = htole64(journal_file_tag_seqnum(f));
+
+ /* Add the tag object itself, so that we can protect its
+ * header. This will exclude the actual hash value in it */
+ r = journal_file_hmac_put_object(f, OBJECT_TAG, p);
+ if (r < 0)
+ return r;
+
+ /* Get the HMAC tag and store it in the object */
+ memcpy(o->tag.tag, gcry_md_read(f->hmac, 0), TAG_LENGTH);
+ f->hmac_running = false;
+
+ return 0;
+}
+
+static int journal_file_hmac_start(JournalFile *f) {
+ uint8_t key[256 / 8]; /* Let's pass 256 bit from FSPRG to HMAC */
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ if (f->hmac_running)
+ return 0;
+
+ /* Prepare HMAC for next cycle */
+ gcry_md_reset(f->hmac);
+ FSPRG_GetKey(fsprg_state(f), key, sizeof(key), 0);
+ gcry_md_setkey(f->hmac, key, sizeof(key));
+
+ f->hmac_running = true;
+
+ return 0;
+}
+
+static int journal_file_get_epoch(JournalFile *f, uint64_t realtime, uint64_t *epoch) {
+ uint64_t t;
+
+ assert(f);
+ assert(epoch);
+ assert(f->authenticate);
+
+ if (le64toh(f->fsprg_header->fsprg_start_usec) == 0 ||
+ le64toh(f->fsprg_header->fsprg_interval_usec) == 0)
+ return -ENOTSUP;
+
+ if (realtime < le64toh(f->fsprg_header->fsprg_start_usec))
+ return -ESTALE;
+
+ t = realtime - le64toh(f->fsprg_header->fsprg_start_usec);
+ t = t / le64toh(f->fsprg_header->fsprg_interval_usec);
+
+ *epoch = t;
+ return 0;
+}
+
+static int journal_file_need_evolve(JournalFile *f, uint64_t realtime) {
+ uint64_t goal, epoch;
+ int r;
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = journal_file_get_epoch(f, realtime, &goal);
+ if (r < 0)
+ return r;
+
+ epoch = FSPRG_GetEpoch(fsprg_state(f));
+ if (epoch > goal)
+ return -ESTALE;
+
+ return epoch != goal;
+}
+
+static int journal_file_evolve(JournalFile *f, uint64_t realtime) {
+ uint64_t goal, epoch;
+ int r;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = journal_file_get_epoch(f, realtime, &goal);
+ if (r < 0)
+ return r;
+
+ epoch = FSPRG_GetEpoch(fsprg_state(f));
+ if (epoch < goal)
+ log_debug("Evolving FSPRG key from epoch %llu to %llu.", (unsigned long long) epoch, (unsigned long long) goal);
+
+ for (;;) {
+ if (epoch > goal)
+ return -ESTALE;
+ if (epoch == goal)
+ return 0;
+
+ FSPRG_Evolve(fsprg_state(f));
+ epoch = FSPRG_GetEpoch(fsprg_state(f));
+ }
+}
+
+int journal_file_maybe_append_tag(JournalFile *f, uint64_t realtime) {
+ int r;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = journal_file_need_evolve(f, realtime);
+ if (r <= 0)
+ return 0;
+
+ r = journal_file_append_tag(f);
+ if (r < 0)
+ return r;
+
+ r = journal_file_evolve(f, realtime);
+ if (r < 0)
+ return r;
+
+ r = journal_file_hmac_start(f);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int journal_file_hmac_put_object(JournalFile *f, int type, uint64_t p) {
+ int r;
+ Object *o;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = journal_file_hmac_start(f);
+ if (r < 0)
+ return r;
+
+ r = journal_file_move_to_object(f, type, p, &o);
+ if (r < 0)
+ return r;
+
+ gcry_md_write(f->hmac, o, offsetof(ObjectHeader, payload));
+
+ switch (o->object.type) {
+
+ case OBJECT_DATA:
+ /* All but: hash and payload are mutable */
+ gcry_md_write(f->hmac, &o->data.hash, sizeof(o->data.hash));
+ gcry_md_write(f->hmac, o->data.payload, le64toh(o->object.size) - offsetof(DataObject, payload));
+ break;
+
+ case OBJECT_ENTRY:
+ /* All */
+ gcry_md_write(f->hmac, &o->entry.seqnum, le64toh(o->object.size) - offsetof(EntryObject, seqnum));
+ break;
+
+ case OBJECT_FIELD_HASH_TABLE:
+ case OBJECT_DATA_HASH_TABLE:
+ case OBJECT_ENTRY_ARRAY:
+ /* Nothing: everything is mutable */
+ break;
+
+ case OBJECT_TAG:
+ /* All but the tag itself */
+ gcry_md_write(f->hmac, &o->tag.seqnum, sizeof(o->tag.seqnum));
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int journal_file_hmac_put_header(JournalFile *f) {
+ int r;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = journal_file_hmac_start(f);
+ if (r < 0)
+ return r;
+
+ /* All but state+reserved, boot_id, arena_size,
+ * tail_object_offset, n_objects, n_entries, tail_seqnum,
+ * head_entry_realtime, tail_entry_realtime,
+ * tail_entry_monotonic, n_data, n_fields, header_tag */
+
+ gcry_md_write(f->hmac, f->header->signature, offsetof(Header, state) - offsetof(Header, signature));
+ gcry_md_write(f->hmac, &f->header->file_id, offsetof(Header, boot_id) - offsetof(Header, file_id));
+ gcry_md_write(f->hmac, &f->header->seqnum_id, offsetof(Header, arena_size) - offsetof(Header, seqnum_id));
+ gcry_md_write(f->hmac, &f->header->data_hash_table_offset, offsetof(Header, tail_object_offset) - offsetof(Header, data_hash_table_offset));
+ gcry_md_write(f->hmac, &f->header->head_entry_seqnum, offsetof(Header, head_entry_realtime) - offsetof(Header, head_entry_seqnum));
+
+ return 0;
+}
+
+int journal_file_load_fsprg(JournalFile *f) {
+ int r, fd = -1;
+ char *p = NULL;
+ struct stat st;
+ FSPRGHeader *m = NULL;
+ sd_id128_t machine;
+
+ assert(f);
+
+ if (!f->authenticate)
+ return 0;
+
+ r = sd_id128_get_machine(&machine);
+ if (r < 0)
+ return r;
+
+ if (asprintf(&p, "/var/log/journal/" SD_ID128_FORMAT_STR "/fsprg",
+ SD_ID128_FORMAT_VAL(machine)) < 0)
+ return -ENOMEM;
+
+ fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
+ if (fd < 0) {
+ log_error("Failed to open %s: %m", p);
+ r = -errno;
+ goto finish;
+ }
+
+ if (fstat(fd, &st) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ if (st.st_size < (off_t) sizeof(FSPRGHeader)) {
+ r = -ENODATA;
+ goto finish;
+ }
+
+ m = mmap(NULL, PAGE_ALIGN(sizeof(FSPRGHeader)), PROT_READ, MAP_SHARED, fd, 0);
+ if (m == MAP_FAILED) {
+ m = NULL;
+ r = -errno;
+ goto finish;
+ }
+
+ if (memcmp(m->signature, FSPRG_HEADER_SIGNATURE, 8) != 0) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ if (m->incompatible_flags != 0) {
+ r = -EPROTONOSUPPORT;
+ goto finish;
+ }
+
+ if (le64toh(m->header_size) < sizeof(FSPRGHeader)) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ if (le64toh(m->state_size) != FSPRG_stateinbytes(m->secpar)) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ f->fsprg_size = le64toh(m->header_size) + le64toh(m->state_size);
+ if ((uint64_t) st.st_size < f->fsprg_size) {
+ r = -ENODATA;
+ goto finish;
+ }
+
+ if (!sd_id128_equal(machine, m->machine_id)) {
+ r = -EHOSTDOWN;
+ goto finish;
+ }
+
+ if (le64toh(m->fsprg_start_usec) <= 0 ||
+ le64toh(m->fsprg_interval_usec) <= 0) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ f->fsprg_header = mmap(NULL, PAGE_ALIGN(f->fsprg_size), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (f->fsprg_header == MAP_FAILED) {
+ f->fsprg_header = NULL;
+ r = -errno;
+ goto finish;
+ }
+
+ r = 0;
+
+finish:
+ if (m)
+ munmap(m, PAGE_ALIGN(sizeof(FSPRGHeader)));
+
+ if (fd >= 0)
+ close_nointr_nofail(fd);
+
+ free(p);
+ return r;
+}
+
+int journal_file_setup_hmac(JournalFile *f) {
+ gcry_error_t e;
+
+ if (!f->authenticate)
+ return 0;
+
+ e = gcry_md_open(&f->hmac, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
+ if (e != 0)
+ return -ENOTSUP;
+
+ return 0;
+}
+
+int journal_file_append_first_tag(JournalFile *f) {
+ int r;
+ uint64_t p;
+
+ if (!f->authenticate)
+ return 0;
+
+ log_debug("Calculating first tag...");
+
+ r = journal_file_hmac_put_header(f);
+ if (r < 0)
+ return r;
+
+ p = le64toh(f->header->field_hash_table_offset);
+ if (p < offsetof(Object, hash_table.items))
+ return -EINVAL;
+ p -= offsetof(Object, hash_table.items);
+
+ r = journal_file_hmac_put_object(f, OBJECT_FIELD_HASH_TABLE, p);
+ if (r < 0)
+ return r;
+
+ p = le64toh(f->header->data_hash_table_offset);
+ if (p < offsetof(Object, hash_table.items))
+ return -EINVAL;
+ p -= offsetof(Object, hash_table.items);
+
+ r = journal_file_hmac_put_object(f, OBJECT_DATA_HASH_TABLE, p);
+ if (r < 0)
+ return r;
+
+ r = journal_file_append_tag(f);
+ if (r < 0)
+ return r;
+
+ return 0;
+}