1 files changed, 525 insertions, 0 deletions

diff --git a/src/libsystemd/sd-journal/journal-authenticate.c b/src/libsystemd/sd-journal/journal-authenticate.c
new file mode 100644
index 0000000..8e7533e
--- /dev/null
+++ b/src/libsystemd/sd-journal/journal-authenticate.c
@@ -0,0 +1,525 @@
+/* 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 void* fssheader_free(FSSHeader *p) {
+        /* mmap() returns MAP_FAILED on error and sets the errno */
+        if (!p || p == MAP_FAILED)
+                return NULL;
+
+        assert_se(munmap(p, PAGE_ALIGN(sizeof(FSSHeader))) >= 0);
+        return NULL;
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(FSSHeader*, fssheader_free);
+
+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 (!JOURNAL_HEADER_SEALED(f->header))
+                return 0;
+
+        if (!f->hmac_running) {
+                r = journal_file_hmac_start(f);
+                if (r < 0)
+                        return r;
+        }
+
+        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 */
+        gcry_error_t err;
+
+        assert(f);
+
+        if (!JOURNAL_HEADER_SEALED(f->header))
+                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);
+        err = gcry_md_setkey(f->hmac, key, sizeof(key));
+        if (gcry_err_code(err) != GPG_ERR_NO_ERROR)
+                return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+                                       "gcry_md_setkey() failed with error code: %s",
+                                       gcry_strerror(err));
+
+        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(JOURNAL_HEADER_SEALED(f->header));
+
+        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 (!JOURNAL_HEADER_SEALED(f->header))
+                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 (!JOURNAL_HEADER_SEALED(f->header))
+                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);
+                if (epoch < goal) {
+                        r = journal_file_append_tag(f);
+                        if (r < 0)
+                                return r;
+                }
+        }
+}
+
+int journal_file_fsprg_seek(JournalFile *f, uint64_t goal) {
+        void *msk;
+        uint64_t epoch;
+
+        assert(f);
+
+        if (!JOURNAL_HEADER_SEALED(f->header))
+                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_safe(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 (!JOURNAL_HEADER_SEALED(f->header))
+                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 (!JOURNAL_HEADER_SEALED(f->header))
+                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, journal_file_data_payload_field(f, o), le64toh(o->object.size) - journal_file_data_payload_offset(f));
+                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(Object, field.payload));
+                break;
+
+        case OBJECT_ENTRY:
+                /* All */
+                gcry_md_write(f->hmac, &o->entry.seqnum, le64toh(o->object.size) - offsetof(Object, entry.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 (!JOURNAL_HEADER_SEALED(f->header))
+                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, tail_entry_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) {
+        _cleanup_close_ int fd = -EBADF;
+        _cleanup_free_ char *path = NULL;
+        _cleanup_(fssheader_freep) FSSHeader *header = NULL;
+        struct stat st;
+        sd_id128_t machine;
+        int r;
+
+        assert(f);
+
+        /* This function is used to determine whether sealing should be enabled in the journal header so we
+         * can't check the header to check if sealing is enabled here. */
+
+        r = sd_id128_get_machine(&machine);
+        if (r < 0)
+                return r;
+
+        if (asprintf(&path, "/var/log/journal/" SD_ID128_FORMAT_STR "/fss",
+                     SD_ID128_FORMAT_VAL(machine)) < 0)
+                return -ENOMEM;
+
+        fd = open(path, O_RDWR|O_CLOEXEC|O_NOCTTY, 0600);
+        if (fd < 0) {
+                if (errno != ENOENT)
+                        log_error_errno(errno, "Failed to open %s: %m", path);
+
+                return -errno;
+        }
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (st.st_size < (off_t) sizeof(FSSHeader))
+                return -ENODATA;
+
+        header = mmap(NULL, PAGE_ALIGN(sizeof(FSSHeader)), PROT_READ, MAP_SHARED, fd, 0);
+        if (header == MAP_FAILED)
+                return -errno;
+
+        if (memcmp(header->signature, FSS_HEADER_SIGNATURE, 8) != 0)
+                return -EBADMSG;
+
+        if (header->incompatible_flags != 0)
+                return -EPROTONOSUPPORT;
+
+        if (le64toh(header->header_size) < sizeof(FSSHeader))
+                return -EBADMSG;
+
+        if (le64toh(header->fsprg_state_size) != FSPRG_stateinbytes(le16toh(header->fsprg_secpar)))
+                return -EBADMSG;
+
+        f->fss_file_size = le64toh(header->header_size) + le64toh(header->fsprg_state_size);
+        if ((uint64_t) st.st_size < f->fss_file_size)
+                return -ENODATA;
+
+        if (!sd_id128_equal(machine, header->machine_id))
+                return -EHOSTDOWN;
+
+        if (le64toh(header->start_usec) <= 0 || le64toh(header->interval_usec) <= 0)
+                return -EBADMSG;
+
+        size_t sz = PAGE_ALIGN(f->fss_file_size);
+        assert(sz < SIZE_MAX);
+        f->fss_file = mmap(NULL, sz, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+        if (f->fss_file == MAP_FAILED) {
+                f->fss_file = NULL;
+                return -errno;
+        }
+
+        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);
+
+        return 0;
+}
+
+int journal_file_hmac_setup(JournalFile *f) {
+        gcry_error_t e;
+
+        if (!JOURNAL_HEADER_SEALED(f->header))
+                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) {
+        uint64_t p;
+        int r;
+
+        if (!JOURNAL_HEADER_SEALED(f->header))
+                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) {
+        _cleanup_free_ uint8_t *seed = NULL;
+        size_t seed_size;
+        const char *k;
+        unsigned long long start, interval;
+        int r;
+
+        assert(f);
+        assert(key);
+
+        seed_size = FSPRG_RECOMMENDED_SEEDLEN;
+        seed = malloc(seed_size);
+        if (!seed)
+                return -ENOMEM;
+
+        k = key;
+        for (size_t c = 0; c < seed_size; c++) {
+                int x, y;
+
+                k = skip_leading_chars(k, "-");
+
+                x = unhexchar(*k);
+                if (x < 0)
+                        return -EINVAL;
+                k++;
+
+                y = unhexchar(*k);
+                if (y < 0)
+                        return -EINVAL;
+                k++;
+
+                seed[c] = (uint8_t) (x * 16 + y);
+        }
+
+        if (*k != '/')
+                return -EINVAL;
+        k++;
+
+        r = sscanf(k, "%llx-%llx", &start, &interval);
+        if (r != 2)
+                return -EINVAL;
+
+        f->fsprg_seed = TAKE_PTR(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 (!JOURNAL_HEADER_SEALED(f->header))
+                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;
+}