diff options
Diffstat (limited to 'crypto/openssh/krl.c')
| -rw-r--r-- | crypto/openssh/krl.c | 1234 |
1 files changed, 1234 insertions, 0 deletions
diff --git a/crypto/openssh/krl.c b/crypto/openssh/krl.c new file mode 100644 index 000000000000..7cf496f58743 --- /dev/null +++ b/crypto/openssh/krl.c @@ -0,0 +1,1234 @@ +/* + * Copyright (c) 2012 Damien Miller <djm@mindrot.org> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* $OpenBSD: krl.c,v 1.9 2013/01/27 10:06:12 djm Exp $ */ + +#include "includes.h" + +#include <sys/types.h> +#include <sys/param.h> +#include <openbsd-compat/sys-tree.h> +#include <openbsd-compat/sys-queue.h> + +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <string.h> +#include <time.h> +#include <unistd.h> + +#include "buffer.h" +#include "key.h" +#include "authfile.h" +#include "misc.h" +#include "log.h" +#include "xmalloc.h" + +#include "krl.h" + +/* #define DEBUG_KRL */ +#ifdef DEBUG_KRL +# define KRL_DBG(x) debug3 x +#else +# define KRL_DBG(x) +#endif + +/* + * Trees of revoked serial numbers, key IDs and keys. This allows + * quick searching, querying and producing lists in canonical order. + */ + +/* Tree of serial numbers. XXX make smarter: really need a real sparse bitmap */ +struct revoked_serial { + u_int64_t lo, hi; + RB_ENTRY(revoked_serial) tree_entry; +}; +static int serial_cmp(struct revoked_serial *a, struct revoked_serial *b); +RB_HEAD(revoked_serial_tree, revoked_serial); +RB_GENERATE_STATIC(revoked_serial_tree, revoked_serial, tree_entry, serial_cmp); + +/* Tree of key IDs */ +struct revoked_key_id { + char *key_id; + RB_ENTRY(revoked_key_id) tree_entry; +}; +static int key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b); +RB_HEAD(revoked_key_id_tree, revoked_key_id); +RB_GENERATE_STATIC(revoked_key_id_tree, revoked_key_id, tree_entry, key_id_cmp); + +/* Tree of blobs (used for keys and fingerprints) */ +struct revoked_blob { + u_char *blob; + u_int len; + RB_ENTRY(revoked_blob) tree_entry; +}; +static int blob_cmp(struct revoked_blob *a, struct revoked_blob *b); +RB_HEAD(revoked_blob_tree, revoked_blob); +RB_GENERATE_STATIC(revoked_blob_tree, revoked_blob, tree_entry, blob_cmp); + +/* Tracks revoked certs for a single CA */ +struct revoked_certs { + Key *ca_key; + struct revoked_serial_tree revoked_serials; + struct revoked_key_id_tree revoked_key_ids; + TAILQ_ENTRY(revoked_certs) entry; +}; +TAILQ_HEAD(revoked_certs_list, revoked_certs); + +struct ssh_krl { + u_int64_t krl_version; + u_int64_t generated_date; + u_int64_t flags; + char *comment; + struct revoked_blob_tree revoked_keys; + struct revoked_blob_tree revoked_sha1s; + struct revoked_certs_list revoked_certs; +}; + +/* Return equal if a and b overlap */ +static int +serial_cmp(struct revoked_serial *a, struct revoked_serial *b) +{ + if (a->hi >= b->lo && a->lo <= b->hi) + return 0; + return a->lo < b->lo ? -1 : 1; +} + +static int +key_id_cmp(struct revoked_key_id *a, struct revoked_key_id *b) +{ + return strcmp(a->key_id, b->key_id); +} + +static int +blob_cmp(struct revoked_blob *a, struct revoked_blob *b) +{ + int r; + + if (a->len != b->len) { + if ((r = memcmp(a->blob, b->blob, MIN(a->len, b->len))) != 0) + return r; + return a->len > b->len ? 1 : -1; + } else + return memcmp(a->blob, b->blob, a->len); +} + +struct ssh_krl * +ssh_krl_init(void) +{ + struct ssh_krl *krl; + + if ((krl = calloc(1, sizeof(*krl))) == NULL) + return NULL; + RB_INIT(&krl->revoked_keys); + RB_INIT(&krl->revoked_sha1s); + TAILQ_INIT(&krl->revoked_certs); + return krl; +} + +static void +revoked_certs_free(struct revoked_certs *rc) +{ + struct revoked_serial *rs, *trs; + struct revoked_key_id *rki, *trki; + + RB_FOREACH_SAFE(rs, revoked_serial_tree, &rc->revoked_serials, trs) { + RB_REMOVE(revoked_serial_tree, &rc->revoked_serials, rs); + free(rs); + } + RB_FOREACH_SAFE(rki, revoked_key_id_tree, &rc->revoked_key_ids, trki) { + RB_REMOVE(revoked_key_id_tree, &rc->revoked_key_ids, rki); + free(rki->key_id); + free(rki); + } + if (rc->ca_key != NULL) + key_free(rc->ca_key); +} + +void +ssh_krl_free(struct ssh_krl *krl) +{ + struct revoked_blob *rb, *trb; + struct revoked_certs *rc, *trc; + + if (krl == NULL) + return; + + free(krl->comment); + RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_keys, trb) { + RB_REMOVE(revoked_blob_tree, &krl->revoked_keys, rb); + free(rb->blob); + free(rb); + } + RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha1s, trb) { + RB_REMOVE(revoked_blob_tree, &krl->revoked_sha1s, rb); + free(rb->blob); + free(rb); + } + TAILQ_FOREACH_SAFE(rc, &krl->revoked_certs, entry, trc) { + TAILQ_REMOVE(&krl->revoked_certs, rc, entry); + revoked_certs_free(rc); + } +} + +void +ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version) +{ + krl->krl_version = version; +} + +void +ssh_krl_set_comment(struct ssh_krl *krl, const char *comment) +{ + free(krl->comment); + if ((krl->comment = strdup(comment)) == NULL) + fatal("%s: strdup", __func__); +} + +/* + * Find the revoked_certs struct for a CA key. If allow_create is set then + * create a new one in the tree if one did not exist already. + */ +static int +revoked_certs_for_ca_key(struct ssh_krl *krl, const Key *ca_key, + struct revoked_certs **rcp, int allow_create) +{ + struct revoked_certs *rc; + + *rcp = NULL; + TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { + if (key_equal(rc->ca_key, ca_key)) { + *rcp = rc; + return 0; + } + } + if (!allow_create) + return 0; + /* If this CA doesn't exist in the list then add it now */ + if ((rc = calloc(1, sizeof(*rc))) == NULL) + return -1; + if ((rc->ca_key = key_from_private(ca_key)) == NULL) { + free(rc); + return -1; + } + RB_INIT(&rc->revoked_serials); + RB_INIT(&rc->revoked_key_ids); + TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry); + debug3("%s: new CA %s", __func__, key_type(ca_key)); + *rcp = rc; + return 0; +} + +static int +insert_serial_range(struct revoked_serial_tree *rt, u_int64_t lo, u_int64_t hi) +{ + struct revoked_serial rs, *ers, *crs, *irs; + + KRL_DBG(("%s: insert %llu:%llu", __func__, lo, hi)); + bzero(&rs, sizeof(rs)); + rs.lo = lo; + rs.hi = hi; + ers = RB_NFIND(revoked_serial_tree, rt, &rs); + if (ers == NULL || serial_cmp(ers, &rs) != 0) { + /* No entry matches. Just insert */ + if ((irs = malloc(sizeof(rs))) == NULL) + return -1; + memcpy(irs, &rs, sizeof(*irs)); + ers = RB_INSERT(revoked_serial_tree, rt, irs); + if (ers != NULL) { + KRL_DBG(("%s: bad: ers != NULL", __func__)); + /* Shouldn't happen */ + free(irs); + return -1; + } + ers = irs; + } else { + KRL_DBG(("%s: overlap found %llu:%llu", __func__, + ers->lo, ers->hi)); + /* + * The inserted entry overlaps an existing one. Grow the + * existing entry. + */ + if (ers->lo > lo) + ers->lo = lo; + if (ers->hi < hi) + ers->hi = hi; + } + /* + * The inserted or revised range might overlap or abut adjacent ones; + * coalesce as necessary. + */ + + /* Check predecessors */ + while ((crs = RB_PREV(revoked_serial_tree, rt, ers)) != NULL) { + KRL_DBG(("%s: pred %llu:%llu", __func__, crs->lo, crs->hi)); + if (ers->lo != 0 && crs->hi < ers->lo - 1) + break; + /* This entry overlaps. */ + if (crs->lo < ers->lo) { + ers->lo = crs->lo; + KRL_DBG(("%s: pred extend %llu:%llu", __func__, + ers->lo, ers->hi)); + } + RB_REMOVE(revoked_serial_tree, rt, crs); + free(crs); + } + /* Check successors */ + while ((crs = RB_NEXT(revoked_serial_tree, rt, ers)) != NULL) { + KRL_DBG(("%s: succ %llu:%llu", __func__, crs->lo, crs->hi)); + if (ers->hi != (u_int64_t)-1 && crs->lo > ers->hi + 1) + break; + /* This entry overlaps. */ + if (crs->hi > ers->hi) { + ers->hi = crs->hi; + KRL_DBG(("%s: succ extend %llu:%llu", __func__, + ers->lo, ers->hi)); + } + RB_REMOVE(revoked_serial_tree, rt, crs); + free(crs); + } + KRL_DBG(("%s: done, final %llu:%llu", __func__, ers->lo, ers->hi)); + return 0; +} + +int +ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const Key *ca_key, + u_int64_t serial) +{ + return ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial, serial); +} + +int +ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl, const Key *ca_key, + u_int64_t lo, u_int64_t hi) +{ + struct revoked_certs *rc; + + if (lo > hi || lo == 0) + return -1; + if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) + return -1; + return insert_serial_range(&rc->revoked_serials, lo, hi); +} + +int +ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const Key *ca_key, + const char *key_id) +{ + struct revoked_key_id *rki, *erki; + struct revoked_certs *rc; + + if (revoked_certs_for_ca_key(krl, ca_key, &rc, 1) != 0) + return -1; + + debug3("%s: revoke %s", __func__, key_id); + if ((rki = calloc(1, sizeof(*rki))) == NULL || + (rki->key_id = strdup(key_id)) == NULL) { + free(rki); + fatal("%s: strdup", __func__); + } + erki = RB_INSERT(revoked_key_id_tree, &rc->revoked_key_ids, rki); + if (erki != NULL) { + free(rki->key_id); + free(rki); + } + return 0; +} + +/* Convert "key" to a public key blob without any certificate information */ +static int +plain_key_blob(const Key *key, u_char **blob, u_int *blen) +{ + Key *kcopy; + int r; + + if ((kcopy = key_from_private(key)) == NULL) + return -1; + if (key_is_cert(kcopy)) { + if (key_drop_cert(kcopy) != 0) { + error("%s: key_drop_cert", __func__); + key_free(kcopy); + return -1; + } + } + r = key_to_blob(kcopy, blob, blen); + free(kcopy); + return r == 0 ? -1 : 0; +} + +/* Revoke a key blob. Ownership of blob is transferred to the tree */ +static int +revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, u_int len) +{ + struct revoked_blob *rb, *erb; + + if ((rb = calloc(1, sizeof(*rb))) == NULL) + return -1; + rb->blob = blob; + rb->len = len; + erb = RB_INSERT(revoked_blob_tree, rbt, rb); + if (erb != NULL) { + free(rb->blob); + free(rb); + } + return 0; +} + +int +ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const Key *key) +{ + u_char *blob; + u_int len; + + debug3("%s: revoke type %s", __func__, key_type(key)); + if (plain_key_blob(key, &blob, &len) != 0) + return -1; + return revoke_blob(&krl->revoked_keys, blob, len); +} + +int +ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const Key *key) +{ + u_char *blob; + u_int len; + + debug3("%s: revoke type %s by sha1", __func__, key_type(key)); + if ((blob = key_fingerprint_raw(key, SSH_FP_SHA1, &len)) == NULL) + return -1; + return revoke_blob(&krl->revoked_sha1s, blob, len); +} + +int +ssh_krl_revoke_key(struct ssh_krl *krl, const Key *key) +{ + if (!key_is_cert(key)) + return ssh_krl_revoke_key_sha1(krl, key); + + if (key_cert_is_legacy(key) || key->cert->serial == 0) { + return ssh_krl_revoke_cert_by_key_id(krl, + key->cert->signature_key, + key->cert->key_id); + } else { + return ssh_krl_revoke_cert_by_serial(krl, + key->cert->signature_key, + key->cert->serial); + } +} + +/* + * Select a copact next section type to emit in a KRL based on the + * current section type, the run length of contiguous revoked serial + * numbers and the gaps from the last and to the next revoked serial. + * Applies a mostly-accurate bit cost model to select the section type + * that will minimise the size of the resultant KRL. + */ +static int +choose_next_state(int current_state, u_int64_t contig, int final, + u_int64_t last_gap, u_int64_t next_gap, int *force_new_section) +{ + int new_state; + u_int64_t cost, cost_list, cost_range, cost_bitmap, cost_bitmap_restart; + + /* + * Avoid unsigned overflows. + * The limits are high enough to avoid confusing the calculations. + */ + contig = MIN(contig, 1ULL<<31); + last_gap = MIN(last_gap, 1ULL<<31); + next_gap = MIN(next_gap, 1ULL<<31); + + /* + * Calculate the cost to switch from the current state to candidates. + * NB. range sections only ever contain a single range, so their + * switching cost is independent of the current_state. + */ + cost_list = cost_bitmap = cost_bitmap_restart = 0; + cost_range = 8; + switch (current_state) { + case KRL_SECTION_CERT_SERIAL_LIST: + cost_bitmap_restart = cost_bitmap = 8 + 64; + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + cost_list = 8; + cost_bitmap_restart = 8 + 64; + break; + case KRL_SECTION_CERT_SERIAL_RANGE: + case 0: + cost_bitmap_restart = cost_bitmap = 8 + 64; + cost_list = 8; + } + + /* Estimate base cost in bits of each section type */ + cost_list += 64 * contig + (final ? 0 : 8+64); + cost_range += (2 * 64) + (final ? 0 : 8+64); + cost_bitmap += last_gap + contig + (final ? 0 : MIN(next_gap, 8+64)); + cost_bitmap_restart += contig + (final ? 0 : MIN(next_gap, 8+64)); + + /* Convert to byte costs for actual comparison */ + cost_list = (cost_list + 7) / 8; + cost_bitmap = (cost_bitmap + 7) / 8; + cost_bitmap_restart = (cost_bitmap_restart + 7) / 8; + cost_range = (cost_range + 7) / 8; + + /* Now pick the best choice */ + *force_new_section = 0; + new_state = KRL_SECTION_CERT_SERIAL_BITMAP; + cost = cost_bitmap; + if (cost_range < cost) { + new_state = KRL_SECTION_CERT_SERIAL_RANGE; + cost = cost_range; + } + if (cost_list < cost) { + new_state = KRL_SECTION_CERT_SERIAL_LIST; + cost = cost_list; + } + if (cost_bitmap_restart < cost) { + new_state = KRL_SECTION_CERT_SERIAL_BITMAP; + *force_new_section = 1; + cost = cost_bitmap_restart; + } + debug3("%s: contig %llu last_gap %llu next_gap %llu final %d, costs:" + "list %llu range %llu bitmap %llu new bitmap %llu, " + "selected 0x%02x%s", __func__, (unsigned long long)contig, + (unsigned long long)last_gap, (unsigned long long)next_gap, final, + (unsigned long long)cost_list, (unsigned long long)cost_range, + (unsigned long long)cost_bitmap, + (unsigned long long)cost_bitmap_restart, new_state, + *force_new_section ? " restart" : ""); + return new_state; +} + +/* Generate a KRL_SECTION_CERTIFICATES KRL section */ +static int +revoked_certs_generate(struct revoked_certs *rc, Buffer *buf) +{ + int final, force_new_sect, r = -1; + u_int64_t i, contig, gap, last = 0, bitmap_start = 0; + struct revoked_serial *rs, *nrs; + struct revoked_key_id *rki; + int next_state, state = 0; + Buffer sect; + u_char *kblob = NULL; + u_int klen; + BIGNUM *bitmap = NULL; + + /* Prepare CA scope key blob if we have one supplied */ + if (key_to_blob(rc->ca_key, &kblob, &klen) == 0) + return -1; + + buffer_init(§); + + /* Store the header */ + buffer_put_string(buf, kblob, klen); + buffer_put_string(buf, NULL, 0); /* Reserved */ + + free(kblob); + + /* Store the revoked serials. */ + for (rs = RB_MIN(revoked_serial_tree, &rc->revoked_serials); + rs != NULL; + rs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs)) { + debug3("%s: serial %llu:%llu state 0x%02x", __func__, + (unsigned long long)rs->lo, (unsigned long long)rs->hi, + state); + + /* Check contiguous length and gap to next section (if any) */ + nrs = RB_NEXT(revoked_serial_tree, &rc->revoked_serials, rs); + final = nrs == NULL; + gap = nrs == NULL ? 0 : nrs->lo - rs->hi; + contig = 1 + (rs->hi - rs->lo); + + /* Choose next state based on these */ + next_state = choose_next_state(state, contig, final, + state == 0 ? 0 : rs->lo - last, gap, &force_new_sect); + + /* + * If the current section is a range section or has a different + * type to the next section, then finish it off now. + */ + if (state != 0 && (force_new_sect || next_state != state || + state == KRL_SECTION_CERT_SERIAL_RANGE)) { + debug3("%s: finish state 0x%02x", __func__, state); + switch (state) { + case KRL_SECTION_CERT_SERIAL_LIST: + case KRL_SECTION_CERT_SERIAL_RANGE: + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + buffer_put_bignum2(§, bitmap); + BN_free(bitmap); + bitmap = NULL; + break; + } + buffer_put_char(buf, state); + buffer_put_string(buf, + buffer_ptr(§), buffer_len(§)); + } + + /* If we are starting a new section then prepare it now */ + if (next_state != state || force_new_sect) { + debug3("%s: start state 0x%02x", __func__, next_state); + state = next_state; + buffer_clear(§); + switch (state) { + case KRL_SECTION_CERT_SERIAL_LIST: + case KRL_SECTION_CERT_SERIAL_RANGE: + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + if ((bitmap = BN_new()) == NULL) + goto out; + bitmap_start = rs->lo; + buffer_put_int64(§, bitmap_start); + break; + } + } + + /* Perform section-specific processing */ + switch (state) { + case KRL_SECTION_CERT_SERIAL_LIST: + for (i = 0; i < contig; i++) + buffer_put_int64(§, rs->lo + i); + break; + case KRL_SECTION_CERT_SERIAL_RANGE: + buffer_put_int64(§, rs->lo); + buffer_put_int64(§, rs->hi); + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + if (rs->lo - bitmap_start > INT_MAX) { + error("%s: insane bitmap gap", __func__); + goto out; + } + for (i = 0; i < contig; i++) { + if (BN_set_bit(bitmap, + rs->lo + i - bitmap_start) != 1) + goto out; + } + break; + } + last = rs->hi; + } + /* Flush the remaining section, if any */ + if (state != 0) { + debug3("%s: serial final flush for state 0x%02x", + __func__, state); + switch (state) { + case KRL_SECTION_CERT_SERIAL_LIST: + case KRL_SECTION_CERT_SERIAL_RANGE: + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + buffer_put_bignum2(§, bitmap); + BN_free(bitmap); + bitmap = NULL; + break; + } + buffer_put_char(buf, state); + buffer_put_string(buf, + buffer_ptr(§), buffer_len(§)); + } + debug3("%s: serial done ", __func__); + + /* Now output a section for any revocations by key ID */ + buffer_clear(§); + RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { + debug3("%s: key ID %s", __func__, rki->key_id); + buffer_put_cstring(§, rki->key_id); + } + if (buffer_len(§) != 0) { + buffer_put_char(buf, KRL_SECTION_CERT_KEY_ID); + buffer_put_string(buf, buffer_ptr(§), + buffer_len(§)); + } + r = 0; + out: + if (bitmap != NULL) + BN_free(bitmap); + buffer_free(§); + return r; +} + +int +ssh_krl_to_blob(struct ssh_krl *krl, Buffer *buf, const Key **sign_keys, + u_int nsign_keys) +{ + int r = -1; + struct revoked_certs *rc; + struct revoked_blob *rb; + Buffer sect; + u_char *kblob = NULL, *sblob = NULL; + u_int klen, slen, i; + + if (krl->generated_date == 0) + krl->generated_date = time(NULL); + + buffer_init(§); + + /* Store the header */ + buffer_append(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1); + buffer_put_int(buf, KRL_FORMAT_VERSION); + buffer_put_int64(buf, krl->krl_version); + buffer_put_int64(buf, krl->generated_date); + buffer_put_int64(buf, krl->flags); + buffer_put_string(buf, NULL, 0); + buffer_put_cstring(buf, krl->comment ? krl->comment : ""); + + /* Store sections for revoked certificates */ + TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { + if (revoked_certs_generate(rc, §) != 0) + goto out; + buffer_put_char(buf, KRL_SECTION_CERTIFICATES); + buffer_put_string(buf, buffer_ptr(§), + buffer_len(§)); + } + + /* Finally, output sections for revocations by public key/hash */ + buffer_clear(§); + RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { + debug3("%s: key len %u ", __func__, rb->len); + buffer_put_string(§, rb->blob, rb->len); + } + if (buffer_len(§) != 0) { + buffer_put_char(buf, KRL_SECTION_EXPLICIT_KEY); + buffer_put_string(buf, buffer_ptr(§), + buffer_len(§)); + } + buffer_clear(§); + RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { + debug3("%s: hash len %u ", __func__, rb->len); + buffer_put_string(§, rb->blob, rb->len); + } + if (buffer_len(§) != 0) { + buffer_put_char(buf, KRL_SECTION_FINGERPRINT_SHA1); + buffer_put_string(buf, buffer_ptr(§), + buffer_len(§)); + } + + for (i = 0; i < nsign_keys; i++) { + if (key_to_blob(sign_keys[i], &kblob, &klen) == 0) + goto out; + + debug3("%s: signature key len %u", __func__, klen); + buffer_put_char(buf, KRL_SECTION_SIGNATURE); + buffer_put_string(buf, kblob, klen); + + if (key_sign(sign_keys[i], &sblob, &slen, + buffer_ptr(buf), buffer_len(buf)) == -1) + goto out; + debug3("%s: signature sig len %u", __func__, slen); + buffer_put_string(buf, sblob, slen); + } + + r = 0; + out: + free(kblob); + free(sblob); + buffer_free(§); + return r; +} + +static void +format_timestamp(u_int64_t timestamp, char *ts, size_t nts) +{ + time_t t; + struct tm *tm; + + t = timestamp; + tm = localtime(&t); + *ts = '\0'; + strftime(ts, nts, "%Y%m%dT%H%M%S", tm); +} + +static int +parse_revoked_certs(Buffer *buf, struct ssh_krl *krl) +{ + int ret = -1, nbits; + u_char type, *blob; + u_int blen; + Buffer subsect; + u_int64_t serial, serial_lo, serial_hi; + BIGNUM *bitmap = NULL; + char *key_id = NULL; + Key *ca_key = NULL; + + buffer_init(&subsect); + + if ((blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL || + buffer_get_string_ptr_ret(buf, NULL) == NULL) { /* reserved */ + error("%s: buffer error", __func__); + goto out; + } + if ((ca_key = key_from_blob(blob, blen)) == NULL) + goto out; + + while (buffer_len(buf) > 0) { + if (buffer_get_char_ret(&type, buf) != 0 || + (blob = buffer_get_string_ptr_ret(buf, &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + buffer_clear(&subsect); + buffer_append(&subsect, blob, blen); + debug3("%s: subsection type 0x%02x", __func__, type); + /* buffer_dump(&subsect); */ + + switch (type) { + case KRL_SECTION_CERT_SERIAL_LIST: + while (buffer_len(&subsect) > 0) { + if (buffer_get_int64_ret(&serial, + &subsect) != 0) { + error("%s: buffer error", __func__); + goto out; + } + if (ssh_krl_revoke_cert_by_serial(krl, ca_key, + serial) != 0) { + error("%s: update failed", __func__); + goto out; + } + } + break; + case KRL_SECTION_CERT_SERIAL_RANGE: + if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || + buffer_get_int64_ret(&serial_hi, &subsect) != 0) { + error("%s: buffer error", __func__); + goto out; + } + if (ssh_krl_revoke_cert_by_serial_range(krl, ca_key, + serial_lo, serial_hi) != 0) { + error("%s: update failed", __func__); + goto out; + } + break; + case KRL_SECTION_CERT_SERIAL_BITMAP: + if ((bitmap = BN_new()) == NULL) { + error("%s: BN_new", __func__); + goto out; + } + if (buffer_get_int64_ret(&serial_lo, &subsect) != 0 || + buffer_get_bignum2_ret(&subsect, bitmap) != 0) { + error("%s: buffer error", __func__); + goto out; + } + if ((nbits = BN_num_bits(bitmap)) < 0) { + error("%s: bitmap bits < 0", __func__); + goto out; + } + for (serial = 0; serial < (u_int)nbits; serial++) { + if (serial > 0 && serial_lo + serial == 0) { + error("%s: bitmap wraps u64", __func__); + goto out; + } + if (!BN_is_bit_set(bitmap, serial)) + continue; + if (ssh_krl_revoke_cert_by_serial(krl, ca_key, + serial_lo + serial) != 0) { + error("%s: update failed", __func__); + goto out; + } + } + BN_free(bitmap); + bitmap = NULL; + break; + case KRL_SECTION_CERT_KEY_ID: + while (buffer_len(&subsect) > 0) { + if ((key_id = buffer_get_cstring_ret(&subsect, + NULL)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + if (ssh_krl_revoke_cert_by_key_id(krl, ca_key, + key_id) != 0) { + error("%s: update failed", __func__); + goto out; + } + free(key_id); + key_id = NULL; + } + break; + default: + error("Unsupported KRL certificate section %u", type); + goto out; + } + if (buffer_len(&subsect) > 0) { + error("KRL certificate section contains unparsed data"); + goto out; + } + } + + ret = 0; + out: + if (ca_key != NULL) + key_free(ca_key); + if (bitmap != NULL) + BN_free(bitmap); + free(key_id); + buffer_free(&subsect); + return ret; +} + + +/* Attempt to parse a KRL, checking its signature (if any) with sign_ca_keys. */ +int +ssh_krl_from_blob(Buffer *buf, struct ssh_krl **krlp, + const Key **sign_ca_keys, u_int nsign_ca_keys) +{ + Buffer copy, sect; + struct ssh_krl *krl; + char timestamp[64]; + int ret = -1, r, sig_seen; + Key *key = NULL, **ca_used = NULL; + u_char type, *blob; + u_int i, j, sig_off, sects_off, blen, format_version, nca_used = 0; + + *krlp = NULL; + if (buffer_len(buf) < sizeof(KRL_MAGIC) - 1 || + memcmp(buffer_ptr(buf), KRL_MAGIC, sizeof(KRL_MAGIC) - 1) != 0) { + debug3("%s: not a KRL", __func__); + /* + * Return success but a NULL *krlp here to signal that the + * file might be a simple list of keys. + */ + return 0; + } + + /* Take a copy of the KRL buffer so we can verify its signature later */ + buffer_init(©); + buffer_append(©, buffer_ptr(buf), buffer_len(buf)); + + buffer_init(§); + buffer_consume(©, sizeof(KRL_MAGIC) - 1); + + if ((krl = ssh_krl_init()) == NULL) { + error("%s: alloc failed", __func__); + goto out; + } + + if (buffer_get_int_ret(&format_version, ©) != 0) { + error("%s: KRL truncated", __func__); + goto out; + } + if (format_version != KRL_FORMAT_VERSION) { + error("%s: KRL unsupported format version %u", + __func__, format_version); + goto out; + } + if (buffer_get_int64_ret(&krl->krl_version, ©) != 0 || + buffer_get_int64_ret(&krl->generated_date, ©) != 0 || + buffer_get_int64_ret(&krl->flags, ©) != 0 || + buffer_get_string_ptr_ret(©, NULL) == NULL || /* reserved */ + (krl->comment = buffer_get_cstring_ret(©, NULL)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + + format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); + debug("KRL version %llu generated at %s%s%s", + (unsigned long long)krl->krl_version, timestamp, + *krl->comment ? ": " : "", krl->comment); + + /* + * 1st pass: verify signatures, if any. This is done to avoid + * detailed parsing of data whose provenance is unverified. + */ + sig_seen = 0; + sects_off = buffer_len(buf) - buffer_len(©); + while (buffer_len(©) > 0) { + if (buffer_get_char_ret(&type, ©) != 0 || + (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + debug3("%s: first pass, section 0x%02x", __func__, type); + if (type != KRL_SECTION_SIGNATURE) { + if (sig_seen) { + error("KRL contains non-signature section " + "after signature"); + goto out; + } + /* Not interested for now. */ + continue; + } + sig_seen = 1; + /* First string component is the signing key */ + if ((key = key_from_blob(blob, blen)) == NULL) { + error("%s: invalid signature key", __func__); + goto out; + } + sig_off = buffer_len(buf) - buffer_len(©); + /* Second string component is the signature itself */ + if ((blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + /* Check signature over entire KRL up to this point */ + if (key_verify(key, blob, blen, + buffer_ptr(buf), buffer_len(buf) - sig_off) == -1) { + error("bad signaure on KRL"); + goto out; + } + /* Check if this key has already signed this KRL */ + for (i = 0; i < nca_used; i++) { + if (key_equal(ca_used[i], key)) { + error("KRL signed more than once with " + "the same key"); + goto out; + } + } + /* Record keys used to sign the KRL */ + ca_used = xrealloc(ca_used, nca_used + 1, sizeof(*ca_used)); + ca_used[nca_used++] = key; + key = NULL; + break; + } + + /* + * 2nd pass: parse and load the KRL, skipping the header to the point + * where the section start. + */ + buffer_append(©, (u_char*)buffer_ptr(buf) + sects_off, + buffer_len(buf) - sects_off); + while (buffer_len(©) > 0) { + if (buffer_get_char_ret(&type, ©) != 0 || + (blob = buffer_get_string_ptr_ret(©, &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + debug3("%s: second pass, section 0x%02x", __func__, type); + buffer_clear(§); + buffer_append(§, blob, blen); + + switch (type) { + case KRL_SECTION_CERTIFICATES: + if ((r = parse_revoked_certs(§, krl)) != 0) + goto out; + break; + case KRL_SECTION_EXPLICIT_KEY: + case KRL_SECTION_FINGERPRINT_SHA1: + while (buffer_len(§) > 0) { + if ((blob = buffer_get_string_ret(§, + &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + if (type == KRL_SECTION_FINGERPRINT_SHA1 && + blen != 20) { + error("%s: bad SHA1 length", __func__); + goto out; + } + if (revoke_blob( + type == KRL_SECTION_EXPLICIT_KEY ? + &krl->revoked_keys : &krl->revoked_sha1s, + blob, blen) != 0) + goto out; /* revoke_blob frees blob */ + } + break; + case KRL_SECTION_SIGNATURE: + /* Handled above, but still need to stay in synch */ + buffer_clear(§); + if ((blob = buffer_get_string_ptr_ret(©, + &blen)) == NULL) { + error("%s: buffer error", __func__); + goto out; + } + break; + default: + error("Unsupported KRL section %u", type); + goto out; + } + if (buffer_len(§) > 0) { + error("KRL section contains unparsed data"); + goto out; + } + } + + /* Check that the key(s) used to sign the KRL weren't revoked */ + sig_seen = 0; + for (i = 0; i < nca_used; i++) { + if (ssh_krl_check_key(krl, ca_used[i]) == 0) + sig_seen = 1; + else { + key_free(ca_used[i]); + ca_used[i] = NULL; + } + } + if (nca_used && !sig_seen) { + error("All keys used to sign KRL were revoked"); + goto out; + } + + /* If we have CA keys, then verify that one was used to sign the KRL */ + if (sig_seen && nsign_ca_keys != 0) { + sig_seen = 0; + for (i = 0; !sig_seen && i < nsign_ca_keys; i++) { + for (j = 0; j < nca_used; j++) { + if (ca_used[j] == NULL) + continue; + if (key_equal(ca_used[j], sign_ca_keys[i])) { + sig_seen = 1; + break; + } + } + } + if (!sig_seen) { + error("KRL not signed with any trusted key"); + goto out; + } + } + + *krlp = krl; + ret = 0; + out: + if (ret != 0) + ssh_krl_free(krl); + for (i = 0; i < nca_used; i++) { + if (ca_used[i] != NULL) + key_free(ca_used[i]); + } + free(ca_used); + if (key != NULL) + key_free(key); + buffer_free(©); + buffer_free(§); + return ret; +} + +/* Checks whether a given key/cert is revoked. Does not check its CA */ +static int +is_key_revoked(struct ssh_krl *krl, const Key *key) +{ + struct revoked_blob rb, *erb; + struct revoked_serial rs, *ers; + struct revoked_key_id rki, *erki; + struct revoked_certs *rc; + + /* Check explicitly revoked hashes first */ + bzero(&rb, sizeof(rb)); + if ((rb.blob = key_fingerprint_raw(key, SSH_FP_SHA1, &rb.len)) == NULL) + return -1; + erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb); + free(rb.blob); + if (erb != NULL) { + debug("%s: revoked by key SHA1", __func__); + return -1; + } + + /* Next, explicit keys */ + bzero(&rb, sizeof(rb)); + if (plain_key_blob(key, &rb.blob, &rb.len) != 0) + return -1; + erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb); + free(rb.blob); + if (erb != NULL) { + debug("%s: revoked by explicit key", __func__); + return -1; + } + + if (!key_is_cert(key)) + return 0; + + /* Check cert revocation */ + if (revoked_certs_for_ca_key(krl, key->cert->signature_key, + &rc, 0) != 0) + return -1; + if (rc == NULL) + return 0; /* No entry for this CA */ + + /* Check revocation by cert key ID */ + bzero(&rki, sizeof(rki)); + rki.key_id = key->cert->key_id; + erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki); + if (erki != NULL) { + debug("%s: revoked by key ID", __func__); + return -1; + } + + /* + * Legacy cert formats lack serial numbers. Zero serials numbers + * are ignored (it's the default when the CA doesn't specify one). + */ + if (key_cert_is_legacy(key) || key->cert->serial == 0) + return 0; + + bzero(&rs, sizeof(rs)); + rs.lo = rs.hi = key->cert->serial; + ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs); + if (ers != NULL) { + KRL_DBG(("%s: %llu matched %llu:%llu", __func__, + key->cert->serial, ers->lo, ers->hi)); + debug("%s: revoked by serial", __func__); + return -1; + } + KRL_DBG(("%s: %llu no match", __func__, key->cert->serial)); + + return 0; +} + +int +ssh_krl_check_key(struct ssh_krl *krl, const Key *key) +{ + int r; + + debug2("%s: checking key", __func__); + if ((r = is_key_revoked(krl, key)) != 0) + return r; + if (key_is_cert(key)) { + debug2("%s: checking CA key", __func__); + if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0) + return r; + } + debug3("%s: key okay", __func__); + return 0; +} + +/* Returns 0 on success, -1 on error or key revoked, -2 if path is not a KRL */ +int +ssh_krl_file_contains_key(const char *path, const Key *key) +{ + Buffer krlbuf; + struct ssh_krl *krl; + int revoked, fd; + + if (path == NULL) + return 0; + + if ((fd = open(path, O_RDONLY)) == -1) { + error("open %s: %s", path, strerror(errno)); + error("Revoked keys file not accessible - refusing public key " + "authentication"); + return -1; + } + buffer_init(&krlbuf); + if (!key_load_file(fd, path, &krlbuf)) { + close(fd); + buffer_free(&krlbuf); + error("Revoked keys file not readable - refusing public key " + "authentication"); + return -1; + } + close(fd); + if (ssh_krl_from_blob(&krlbuf, &krl, NULL, 0) != 0) { + buffer_free(&krlbuf); + error("Invalid KRL, refusing public key " + "authentication"); + return -1; + } + buffer_free(&krlbuf); + if (krl == NULL) { + debug3("%s: %s is not a KRL file", __func__, path); + return -2; + } + debug2("%s: checking KRL %s", __func__, path); + revoked = ssh_krl_check_key(krl, key) != 0; + ssh_krl_free(krl); + return revoked ? -1 : 0; +} |