journal: split up journal-file.c

1 files changed, 434 insertions, 0 deletions

diff --git a/src/journal/journal-authenticate.c b/src/journal/journal-authenticate.c
new file mode 100644
index 0000000000..827e4e4fb9
--- /dev/null
+++ b/src/journal/journal-authenticate.c
@@ -0,0 +1,434 @@
+/*-*- 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;
+}