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-rw-r--r--src/journal/journal-authenticate.c536
1 files changed, 536 insertions, 0 deletions
diff --git a/src/journal/journal-authenticate.c b/src/journal/journal-authenticate.c
new file mode 100644
index 0000000..a5ff987
--- /dev/null
+++ b/src/journal/journal-authenticate.c
@@ -0,0 +1,536 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include "fd-util.h"
+#include "fsprg.h"
+#include "gcrypt-util.h"
+#include "hexdecoct.h"
+#include "journal-authenticate.h"
+#include "journal-def.h"
+#include "journal-file.h"
+#include "memory-util.h"
+#include "time-util.h"
+
+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->seal)
+ return 0;
+
+ if (!f->hmac_running)
+ return 0;
+
+ 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));
+ o->tag.epoch = htole64(FSPRG_GetEpoch(f->fsprg_state));
+
+ log_debug("Writing tag %"PRIu64" for epoch %"PRIu64"",
+ le64toh(o->tag.seqnum),
+ FSPRG_GetEpoch(f->fsprg_state));
+
+ /* 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, o, 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;
+}
+
+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->seal)
+ return 0;
+
+ if (f->hmac_running)
+ return 0;
+
+ /* Prepare HMAC for next cycle */
+ gcry_md_reset(f->hmac);
+ FSPRG_GetKey(f->fsprg_state, 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->seal);
+
+ if (f->fss_start_usec == 0 ||
+ f->fss_interval_usec == 0)
+ return -EOPNOTSUPP;
+
+ if (realtime < f->fss_start_usec)
+ return -ESTALE;
+
+ t = realtime - f->fss_start_usec;
+ t = t / f->fss_interval_usec;
+
+ *epoch = t;
+ return 0;
+}
+
+static int journal_file_fsprg_need_evolve(JournalFile *f, uint64_t realtime) {
+ uint64_t goal, epoch;
+ int r;
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ r = journal_file_get_epoch(f, realtime, &goal);
+ if (r < 0)
+ return r;
+
+ epoch = FSPRG_GetEpoch(f->fsprg_state);
+ if (epoch > goal)
+ return -ESTALE;
+
+ return epoch != goal;
+}
+
+int journal_file_fsprg_evolve(JournalFile *f, uint64_t realtime) {
+ uint64_t goal, epoch;
+ int r;
+
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ r = journal_file_get_epoch(f, realtime, &goal);
+ if (r < 0)
+ return r;
+
+ epoch = FSPRG_GetEpoch(f->fsprg_state);
+ if (epoch < goal)
+ log_debug("Evolving FSPRG key from epoch %"PRIu64" to %"PRIu64".", epoch, goal);
+
+ for (;;) {
+ if (epoch > goal)
+ return -ESTALE;
+ if (epoch == goal)
+ return 0;
+
+ FSPRG_Evolve(f->fsprg_state);
+ epoch = FSPRG_GetEpoch(f->fsprg_state);
+ }
+}
+
+int journal_file_fsprg_seek(JournalFile *f, uint64_t goal) {
+ void *msk;
+ uint64_t epoch;
+
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ assert(f->fsprg_seed);
+
+ if (f->fsprg_state) {
+ /* Cheaper... */
+
+ epoch = FSPRG_GetEpoch(f->fsprg_state);
+ if (goal == epoch)
+ return 0;
+
+ if (goal == epoch+1) {
+ FSPRG_Evolve(f->fsprg_state);
+ return 0;
+ }
+ } else {
+ f->fsprg_state_size = FSPRG_stateinbytes(FSPRG_RECOMMENDED_SECPAR);
+ f->fsprg_state = malloc(f->fsprg_state_size);
+
+ if (!f->fsprg_state)
+ return -ENOMEM;
+ }
+
+ log_debug("Seeking FSPRG key to %"PRIu64".", goal);
+
+ msk = alloca(FSPRG_mskinbytes(FSPRG_RECOMMENDED_SECPAR));
+ FSPRG_GenMK(msk, NULL, f->fsprg_seed, f->fsprg_seed_size, FSPRG_RECOMMENDED_SECPAR);
+ FSPRG_Seek(f->fsprg_state, goal, msk, f->fsprg_seed, f->fsprg_seed_size);
+ return 0;
+}
+
+int journal_file_maybe_append_tag(JournalFile *f, uint64_t realtime) {
+ int r;
+
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ if (realtime <= 0)
+ realtime = now(CLOCK_REALTIME);
+
+ r = journal_file_fsprg_need_evolve(f, realtime);
+ if (r <= 0)
+ return 0;
+
+ r = journal_file_append_tag(f);
+ if (r < 0)
+ return r;
+
+ r = journal_file_fsprg_evolve(f, realtime);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int journal_file_hmac_put_object(JournalFile *f, ObjectType type, Object *o, uint64_t p) {
+ int r;
+
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ r = journal_file_hmac_start(f);
+ if (r < 0)
+ return r;
+
+ if (!o) {
+ r = journal_file_move_to_object(f, type, p, &o);
+ if (r < 0)
+ return r;
+ } else {
+ if (type > OBJECT_UNUSED && o->object.type != type)
+ return -EBADMSG;
+ }
+
+ 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_FIELD:
+ /* Same here */
+ gcry_md_write(f->hmac, &o->field.hash, sizeof(o->field.hash));
+ gcry_md_write(f->hmac, o->field.payload, le64toh(o->object.size) - offsetof(FieldObject, 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));
+ gcry_md_write(f->hmac, &o->tag.epoch, sizeof(o->tag.epoch));
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int journal_file_hmac_put_header(JournalFile *f) {
+ int r;
+
+ assert(f);
+
+ if (!f->seal)
+ 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_entry_seqnum, head_entry_seqnum, entry_array_offset,
+ * head_entry_realtime, tail_entry_realtime,
+ * tail_entry_monotonic, n_data, n_fields, n_tags,
+ * n_entry_arrays. */
+
+ 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));
+
+ return 0;
+}
+
+int journal_file_fss_load(JournalFile *f) {
+ int r, fd = -1;
+ char *p = NULL;
+ struct stat st;
+ FSSHeader *m = NULL;
+ sd_id128_t machine;
+
+ assert(f);
+
+ if (!f->seal)
+ return 0;
+
+ r = sd_id128_get_machine(&machine);
+ if (r < 0)
+ return r;
+
+ if (asprintf(&p, "/var/log/journal/" SD_ID128_FORMAT_STR "/fss",
+ SD_ID128_FORMAT_VAL(machine)) < 0)
+ return -ENOMEM;
+
+ fd = open(p, O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
+ if (fd < 0) {
+ if (errno != ENOENT)
+ log_error_errno(errno, "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(FSSHeader)) {
+ r = -ENODATA;
+ goto finish;
+ }
+
+ m = mmap(NULL, PAGE_ALIGN(sizeof(FSSHeader)), PROT_READ, MAP_SHARED, fd, 0);
+ if (m == MAP_FAILED) {
+ m = NULL;
+ r = -errno;
+ goto finish;
+ }
+
+ if (memcmp(m->signature, FSS_HEADER_SIGNATURE, 8) != 0) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ if (m->incompatible_flags != 0) {
+ r = -EPROTONOSUPPORT;
+ goto finish;
+ }
+
+ if (le64toh(m->header_size) < sizeof(FSSHeader)) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ if (le64toh(m->fsprg_state_size) != FSPRG_stateinbytes(le16toh(m->fsprg_secpar))) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ f->fss_file_size = le64toh(m->header_size) + le64toh(m->fsprg_state_size);
+ if ((uint64_t) st.st_size < f->fss_file_size) {
+ r = -ENODATA;
+ goto finish;
+ }
+
+ if (!sd_id128_equal(machine, m->machine_id)) {
+ r = -EHOSTDOWN;
+ goto finish;
+ }
+
+ if (le64toh(m->start_usec) <= 0 ||
+ le64toh(m->interval_usec) <= 0) {
+ r = -EBADMSG;
+ goto finish;
+ }
+
+ f->fss_file = mmap(NULL, PAGE_ALIGN(f->fss_file_size), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (f->fss_file == MAP_FAILED) {
+ f->fss_file = NULL;
+ r = -errno;
+ goto finish;
+ }
+
+ f->fss_start_usec = le64toh(f->fss_file->start_usec);
+ f->fss_interval_usec = le64toh(f->fss_file->interval_usec);
+
+ f->fsprg_state = (uint8_t*) f->fss_file + le64toh(f->fss_file->header_size);
+ f->fsprg_state_size = le64toh(f->fss_file->fsprg_state_size);
+
+ r = 0;
+
+finish:
+ if (m)
+ munmap(m, PAGE_ALIGN(sizeof(FSSHeader)));
+
+ safe_close(fd);
+ free(p);
+
+ return r;
+}
+
+int journal_file_hmac_setup(JournalFile *f) {
+ gcry_error_t e;
+
+ if (!f->seal)
+ return 0;
+
+ initialize_libgcrypt(true);
+
+ e = gcry_md_open(&f->hmac, GCRY_MD_SHA256, GCRY_MD_FLAG_HMAC);
+ if (e != 0)
+ return -EOPNOTSUPP;
+
+ return 0;
+}
+
+int journal_file_append_first_tag(JournalFile *f) {
+ int r;
+ uint64_t p;
+
+ if (!f->seal)
+ 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, NULL, 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, NULL, p);
+ if (r < 0)
+ return r;
+
+ r = journal_file_append_tag(f);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int journal_file_parse_verification_key(JournalFile *f, const char *key) {
+ uint8_t *seed;
+ size_t seed_size, c;
+ const char *k;
+ int r;
+ unsigned long long start, interval;
+
+ seed_size = FSPRG_RECOMMENDED_SEEDLEN;
+ seed = malloc(seed_size);
+ if (!seed)
+ return -ENOMEM;
+
+ k = key;
+ for (c = 0; c < seed_size; c++) {
+ int x, y;
+
+ while (*k == '-')
+ k++;
+
+ x = unhexchar(*k);
+ if (x < 0) {
+ free(seed);
+ return -EINVAL;
+ }
+ k++;
+ y = unhexchar(*k);
+ if (y < 0) {
+ free(seed);
+ return -EINVAL;
+ }
+ k++;
+
+ seed[c] = (uint8_t) (x * 16 + y);
+ }
+
+ if (*k != '/') {
+ free(seed);
+ return -EINVAL;
+ }
+ k++;
+
+ r = sscanf(k, "%llx-%llx", &start, &interval);
+ if (r != 2) {
+ free(seed);
+ return -EINVAL;
+ }
+
+ f->fsprg_seed = seed;
+ f->fsprg_seed_size = seed_size;
+
+ f->fss_start_usec = start * interval;
+ f->fss_interval_usec = interval;
+
+ return 0;
+}
+
+bool journal_file_next_evolve_usec(JournalFile *f, usec_t *u) {
+ uint64_t epoch;
+
+ assert(f);
+ assert(u);
+
+ if (!f->seal)
+ return false;
+
+ epoch = FSPRG_GetEpoch(f->fsprg_state);
+
+ *u = (usec_t) (f->fss_start_usec + f->fss_interval_usec * epoch + f->fss_interval_usec);
+
+ return true;
+}
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