diff options
Diffstat (limited to 'src/journal/journal-authenticate.c')
| -rw-r--r-- | src/journal/journal-authenticate.c | 434 |
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; +} |