diff options
Diffstat (limited to '')
| -rw-r--r-- | src/libsystemd/sd-journal/journal-authenticate.c | 541 |
1 files changed, 541 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..1cb8943 --- /dev/null +++ b/src/libsystemd/sd-journal/journal-authenticate.c @@ -0,0 +1,541 @@ +/* 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 (!JOURNAL_HEADER_SEALED(f->header)) + 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 */ + 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); + } +} + +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, 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); + + /* 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(&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 (!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) { + int r; + uint64_t p; + + 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) { + 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 (!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; +} |