/* $NetBSD: krl.c,v 1.21.2.2 2023/11/02 22:15:21 sborrill Exp $ */ /* $OpenBSD: krl.c,v 1.59 2023/07/17 05:22:30 djm Exp $ */ /* * Copyright (c) 2012 Damien Miller * * 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. */ #include "includes.h" __RCSID("$NetBSD: krl.c,v 1.21.2.2 2023/11/02 22:15:21 sborrill Exp $"); #include #include #include #include #include #include #include #include #include #include #include "sshbuf.h" #include "ssherr.h" #include "sshkey.h" #include "authfile.h" #include "misc.h" #include "log.h" #include "digest.h" #include "bitmap.h" #include "utf8.h" #include "krl.h" /* #define DEBUG_KRL */ #ifdef DEBUG_KRL # define KRL_DBG(x) debug3_f 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; size_t 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 { struct sshkey *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_blob_tree revoked_sha256s; 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, MINIMUM(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); RB_INIT(&krl->revoked_sha256s); 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); } sshkey_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); } RB_FOREACH_SAFE(rb, revoked_blob_tree, &krl->revoked_sha256s, trb) { RB_REMOVE(revoked_blob_tree, &krl->revoked_sha256s, 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); } free(krl); } void ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version) { krl->krl_version = version; } int ssh_krl_set_comment(struct ssh_krl *krl, const char *comment) { free(krl->comment); if ((krl->comment = strdup(comment)) == NULL) return SSH_ERR_ALLOC_FAIL; return 0; } /* * 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 struct sshkey *ca_key, struct revoked_certs **rcp, int allow_create) { struct revoked_certs *rc; int r; *rcp = NULL; TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { if ((ca_key == NULL && rc->ca_key == NULL) || sshkey_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 SSH_ERR_ALLOC_FAIL; if (ca_key == NULL) rc->ca_key = NULL; else if ((r = sshkey_from_private(ca_key, &rc->ca_key)) != 0) { free(rc); return r; } RB_INIT(&rc->revoked_serials); RB_INIT(&rc->revoked_key_ids); TAILQ_INSERT_TAIL(&krl->revoked_certs, rc, entry); KRL_DBG(("new CA %s", ca_key == NULL ? "*" : sshkey_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(("insert %"PRIu64":%"PRIu64, lo, hi)); memset(&rs, 0, 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 SSH_ERR_ALLOC_FAIL; memcpy(irs, &rs, sizeof(*irs)); ers = RB_INSERT(revoked_serial_tree, rt, irs); if (ers != NULL) { KRL_DBG(("bad: ers != NULL")); /* Shouldn't happen */ free(irs); return SSH_ERR_INTERNAL_ERROR; } ers = irs; } else { KRL_DBG(("overlap found %"PRIu64":%"PRIu64, 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(("pred %"PRIu64":%"PRIu64, 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(("pred extend %"PRIu64":%"PRIu64, 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(("succ %"PRIu64":%"PRIu64, 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(("succ extend %"PRIu64":%"PRIu64, ers->lo, ers->hi)); } RB_REMOVE(revoked_serial_tree, rt, crs); free(crs); } KRL_DBG(("done, final %"PRIu64":%"PRIu64, ers->lo, ers->hi)); return 0; } int ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl, const struct sshkey *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 struct sshkey *ca_key, u_int64_t lo, u_int64_t hi) { struct revoked_certs *rc; int r; if (lo > hi || lo == 0) return SSH_ERR_INVALID_ARGUMENT; if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0) return r; return insert_serial_range(&rc->revoked_serials, lo, hi); } int ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl, const struct sshkey *ca_key, const char *key_id) { struct revoked_key_id *rki, *erki; struct revoked_certs *rc; int r; if ((r = revoked_certs_for_ca_key(krl, ca_key, &rc, 1)) != 0) return r; KRL_DBG(("revoke %s", key_id)); if ((rki = calloc(1, sizeof(*rki))) == NULL || (rki->key_id = strdup(key_id)) == NULL) { free(rki); return SSH_ERR_ALLOC_FAIL; } 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 struct sshkey *key, u_char **blob, size_t *blen) { struct sshkey *kcopy; int r; if ((r = sshkey_from_private(key, &kcopy)) != 0) return r; if (sshkey_is_cert(kcopy)) { if ((r = sshkey_drop_cert(kcopy)) != 0) { sshkey_free(kcopy); return r; } } r = sshkey_to_blob(kcopy, blob, blen); sshkey_free(kcopy); return r; } /* Revoke a key blob. Ownership of blob is transferred to the tree */ static int revoke_blob(struct revoked_blob_tree *rbt, u_char *blob, size_t len) { struct revoked_blob *rb, *erb; if ((rb = calloc(1, sizeof(*rb))) == NULL) return SSH_ERR_ALLOC_FAIL; 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 struct sshkey *key) { u_char *blob; size_t len; int r; debug3_f("revoke type %s", sshkey_type(key)); if ((r = plain_key_blob(key, &blob, &len)) != 0) return r; return revoke_blob(&krl->revoked_keys, blob, len); } static int revoke_by_hash(struct revoked_blob_tree *target, const u_char *p, size_t len) { u_char *blob; int r; /* need to copy hash, as revoke_blob steals ownership */ if ((blob = malloc(len)) == NULL) return SSH_ERR_SYSTEM_ERROR; memcpy(blob, p, len); if ((r = revoke_blob(target, blob, len)) != 0) { free(blob); return r; } return 0; } int ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const u_char *p, size_t len) { debug3_f("revoke by sha1"); if (len != 20) return SSH_ERR_INVALID_FORMAT; return revoke_by_hash(&krl->revoked_sha1s, p, len); } int ssh_krl_revoke_key_sha256(struct ssh_krl *krl, const u_char *p, size_t len) { debug3_f("revoke by sha256"); if (len != 32) return SSH_ERR_INVALID_FORMAT; return revoke_by_hash(&krl->revoked_sha256s, p, len); } int ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key) { /* XXX replace with SHA256? */ if (!sshkey_is_cert(key)) return ssh_krl_revoke_key_explicit(krl, key); if (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 the most compact section type to emit next 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 = MINIMUM(contig, 1ULL<<31); last_gap = MINIMUM(last_gap, 1ULL<<31); next_gap = MINIMUM(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 : MINIMUM(next_gap, 8+64)); cost_bitmap_restart += contig + (final ? 0 : MINIMUM(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; } KRL_DBG(("contig %llu last_gap %llu next_gap %llu final %d, costs:" "list %llu range %llu bitmap %llu new bitmap %llu, " "selected 0x%02x%s", (long long unsigned)contig, (long long unsigned)last_gap, (long long unsigned)next_gap, final, (long long unsigned)cost_list, (long long unsigned)cost_range, (long long unsigned)cost_bitmap, (long long unsigned)cost_bitmap_restart, new_state, *force_new_section ? " restart" : "")); return new_state; } static int put_bitmap(struct sshbuf *buf, struct bitmap *bitmap) { size_t len; u_char *blob; int r; len = bitmap_nbytes(bitmap); if ((blob = malloc(len)) == NULL) return SSH_ERR_ALLOC_FAIL; if (bitmap_to_string(bitmap, blob, len) != 0) { free(blob); return SSH_ERR_INTERNAL_ERROR; } r = sshbuf_put_bignum2_bytes(buf, blob, len); free(blob); return r; } /* Generate a KRL_SECTION_CERTIFICATES KRL section */ static int revoked_certs_generate(struct revoked_certs *rc, struct sshbuf *buf) { int final, force_new_sect, r = SSH_ERR_INTERNAL_ERROR; 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; struct sshbuf *sect; struct bitmap *bitmap = NULL; if ((sect = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; /* Store the header: optional CA scope key, reserved */ if (rc->ca_key == NULL) { if ((r = sshbuf_put_string(buf, NULL, 0)) != 0) goto out; } else { if ((r = sshkey_puts(rc->ca_key, buf)) != 0) goto out; } if ((r = sshbuf_put_string(buf, NULL, 0)) != 0) goto out; /* 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)) { KRL_DBG(("serial %llu:%llu state 0x%02x", (long long unsigned)rs->lo, (long long unsigned)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)) { KRL_DBG(("finish state 0x%02x", state)); switch (state) { case KRL_SECTION_CERT_SERIAL_LIST: case KRL_SECTION_CERT_SERIAL_RANGE: break; case KRL_SECTION_CERT_SERIAL_BITMAP: if ((r = put_bitmap(sect, bitmap)) != 0) goto out; bitmap_free(bitmap); bitmap = NULL; break; } if ((r = sshbuf_put_u8(buf, state)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; sshbuf_reset(sect); } /* If we are starting a new section then prepare it now */ if (next_state != state || force_new_sect) { KRL_DBG(("start state 0x%02x", next_state)); state = next_state; sshbuf_reset(sect); switch (state) { case KRL_SECTION_CERT_SERIAL_LIST: case KRL_SECTION_CERT_SERIAL_RANGE: break; case KRL_SECTION_CERT_SERIAL_BITMAP: if ((bitmap = bitmap_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } bitmap_start = rs->lo; if ((r = sshbuf_put_u64(sect, bitmap_start)) != 0) goto out; break; } } /* Perform section-specific processing */ switch (state) { case KRL_SECTION_CERT_SERIAL_LIST: for (i = 0; i < contig; i++) { if ((r = sshbuf_put_u64(sect, rs->lo + i)) != 0) goto out; } break; case KRL_SECTION_CERT_SERIAL_RANGE: if ((r = sshbuf_put_u64(sect, rs->lo)) != 0 || (r = sshbuf_put_u64(sect, rs->hi)) != 0) goto out; break; case KRL_SECTION_CERT_SERIAL_BITMAP: if (rs->lo - bitmap_start > INT_MAX) { error_f("insane bitmap gap"); goto out; } for (i = 0; i < contig; i++) { if (bitmap_set_bit(bitmap, rs->lo + i - bitmap_start) != 0) { r = SSH_ERR_ALLOC_FAIL; goto out; } } break; } last = rs->hi; } /* Flush the remaining section, if any */ if (state != 0) { KRL_DBG(("serial final flush for state 0x%02x", state)); switch (state) { case KRL_SECTION_CERT_SERIAL_LIST: case KRL_SECTION_CERT_SERIAL_RANGE: break; case KRL_SECTION_CERT_SERIAL_BITMAP: if ((r = put_bitmap(sect, bitmap)) != 0) goto out; bitmap_free(bitmap); bitmap = NULL; break; } if ((r = sshbuf_put_u8(buf, state)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } KRL_DBG(("serial done ")); /* Now output a section for any revocations by key ID */ sshbuf_reset(sect); RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { KRL_DBG(("key ID %s", rki->key_id)); if ((r = sshbuf_put_cstring(sect, rki->key_id)) != 0) goto out; } if (sshbuf_len(sect) != 0) { if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERT_KEY_ID)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } r = 0; out: bitmap_free(bitmap); sshbuf_free(sect); return r; } int ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf) { int r = SSH_ERR_INTERNAL_ERROR; struct revoked_certs *rc; struct revoked_blob *rb; struct sshbuf *sect; u_char *sblob = NULL; if (krl->generated_date == 0) krl->generated_date = time(NULL); if ((sect = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; /* Store the header */ if ((r = sshbuf_put(buf, KRL_MAGIC, sizeof(KRL_MAGIC) - 1)) != 0 || (r = sshbuf_put_u32(buf, KRL_FORMAT_VERSION)) != 0 || (r = sshbuf_put_u64(buf, krl->krl_version)) != 0 || (r = sshbuf_put_u64(buf, krl->generated_date)) != 0 || (r = sshbuf_put_u64(buf, krl->flags)) != 0 || (r = sshbuf_put_string(buf, NULL, 0)) != 0 || (r = sshbuf_put_cstring(buf, krl->comment)) != 0) goto out; /* Store sections for revoked certificates */ TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { sshbuf_reset(sect); if ((r = revoked_certs_generate(rc, sect)) != 0) goto out; if ((r = sshbuf_put_u8(buf, KRL_SECTION_CERTIFICATES)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } /* Finally, output sections for revocations by public key/hash */ sshbuf_reset(sect); RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { KRL_DBG(("key len %zu ", rb->len)); if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0) goto out; } if (sshbuf_len(sect) != 0) { if ((r = sshbuf_put_u8(buf, KRL_SECTION_EXPLICIT_KEY)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } sshbuf_reset(sect); RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { KRL_DBG(("hash len %zu ", rb->len)); if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0) goto out; } if (sshbuf_len(sect) != 0) { if ((r = sshbuf_put_u8(buf, KRL_SECTION_FINGERPRINT_SHA1)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } sshbuf_reset(sect); RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) { KRL_DBG(("hash len %zu ", rb->len)); if ((r = sshbuf_put_string(sect, rb->blob, rb->len)) != 0) goto out; } if (sshbuf_len(sect) != 0) { if ((r = sshbuf_put_u8(buf, KRL_SECTION_FINGERPRINT_SHA256)) != 0 || (r = sshbuf_put_stringb(buf, sect)) != 0) goto out; } /* success */ r = 0; out: free(sblob); sshbuf_free(sect); 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); if (tm == NULL) strlcpy(ts, "", nts); else { *ts = '\0'; strftime(ts, nts, "%Y%m%dT%H%M%S", tm); } } static int cert_extension_subsection(struct sshbuf *subsect, struct ssh_krl *krl) { int r = SSH_ERR_INTERNAL_ERROR; u_char critical = 1; struct sshbuf *value = NULL; char *name = NULL; if ((r = sshbuf_get_cstring(subsect, &name, NULL)) != 0 || (r = sshbuf_get_u8(subsect, &critical)) != 0 || (r = sshbuf_froms(subsect, &value)) != 0) { debug_fr(r, "parse"); error("KRL has invalid certificate extension subsection"); r = SSH_ERR_INVALID_FORMAT; goto out; } if (sshbuf_len(subsect) != 0) { error("KRL has invalid certificate extension subsection: " "trailing data"); r = SSH_ERR_INVALID_FORMAT; goto out; } debug_f("cert extension %s critical %u len %zu", name, critical, sshbuf_len(value)); /* no extensions are currently supported */ if (critical) { error("KRL contains unsupported critical certificate " "subsection \"%s\"", name); r = SSH_ERR_FEATURE_UNSUPPORTED; goto out; } /* success */ r = 0; out: free(name); sshbuf_free(value); return r; } static int parse_revoked_certs(struct sshbuf *buf, struct ssh_krl *krl) { int r = SSH_ERR_INTERNAL_ERROR; u_char type; const u_char *blob; size_t blen, nbits; struct sshbuf *subsect = NULL; u_int64_t serial, serial_lo, serial_hi; struct bitmap *bitmap = NULL; char *key_id = NULL; struct sshkey *ca_key = NULL; if ((subsect = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; /* Header: key, reserved */ if ((r = sshbuf_get_string_direct(buf, &blob, &blen)) != 0 || (r = sshbuf_skip_string(buf)) != 0) goto out; if (blen != 0 && (r = sshkey_from_blob(blob, blen, &ca_key)) != 0) goto out; while (sshbuf_len(buf) > 0) { sshbuf_free(subsect); subsect = NULL; if ((r = sshbuf_get_u8(buf, &type)) != 0 || (r = sshbuf_froms(buf, &subsect)) != 0) goto out; KRL_DBG(("subsection type 0x%02x", type)); /* sshbuf_dump(subsect, stderr); */ switch (type) { case KRL_SECTION_CERT_SERIAL_LIST: while (sshbuf_len(subsect) > 0) { if ((r = sshbuf_get_u64(subsect, &serial)) != 0) goto out; if ((r = ssh_krl_revoke_cert_by_serial(krl, ca_key, serial)) != 0) goto out; } break; case KRL_SECTION_CERT_SERIAL_RANGE: if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 || (r = sshbuf_get_u64(subsect, &serial_hi)) != 0) goto out; if ((r = ssh_krl_revoke_cert_by_serial_range(krl, ca_key, serial_lo, serial_hi)) != 0) goto out; break; case KRL_SECTION_CERT_SERIAL_BITMAP: if ((bitmap = bitmap_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshbuf_get_u64(subsect, &serial_lo)) != 0 || (r = sshbuf_get_bignum2_bytes_direct(subsect, &blob, &blen)) != 0) goto out; if (bitmap_from_string(bitmap, blob, blen) != 0) { r = SSH_ERR_INVALID_FORMAT; goto out; } nbits = bitmap_nbits(bitmap); for (serial = 0; serial < (u_int64_t)nbits; serial++) { if (serial > 0 && serial_lo + serial == 0) { error_f("bitmap wraps u64"); r = SSH_ERR_INVALID_FORMAT; goto out; } if (!bitmap_test_bit(bitmap, serial)) continue; if ((r = ssh_krl_revoke_cert_by_serial(krl, ca_key, serial_lo + serial)) != 0) goto out; } bitmap_free(bitmap); bitmap = NULL; break; case KRL_SECTION_CERT_KEY_ID: while (sshbuf_len(subsect) > 0) { if ((r = sshbuf_get_cstring(subsect, &key_id, NULL)) != 0) goto out; if ((r = ssh_krl_revoke_cert_by_key_id(krl, ca_key, key_id)) != 0) goto out; free(key_id); key_id = NULL; } break; case KRL_SECTION_CERT_EXTENSION: if ((r = cert_extension_subsection(subsect, krl)) != 0) goto out; break; default: error("Unsupported KRL certificate section %u", type); r = SSH_ERR_INVALID_FORMAT; goto out; } if (sshbuf_len(subsect) > 0) { error("KRL certificate section contains unparsed data"); r = SSH_ERR_INVALID_FORMAT; goto out; } } r = 0; out: if (bitmap != NULL) bitmap_free(bitmap); free(key_id); sshkey_free(ca_key); sshbuf_free(subsect); return r; } static int blob_section(struct sshbuf *sect, struct revoked_blob_tree *target_tree, size_t expected_len) { u_char *rdata = NULL; size_t rlen = 0; int r; while (sshbuf_len(sect) > 0) { if ((r = sshbuf_get_string(sect, &rdata, &rlen)) != 0) return r; if (expected_len != 0 && rlen != expected_len) { error_f("bad length"); free(rdata); return SSH_ERR_INVALID_FORMAT; } if ((r = revoke_blob(target_tree, rdata, rlen)) != 0) { free(rdata); return r; } } return 0; } static int extension_section(struct sshbuf *sect, struct ssh_krl *krl) { int r = SSH_ERR_INTERNAL_ERROR; u_char critical = 1; struct sshbuf *value = NULL; char *name = NULL; if ((r = sshbuf_get_cstring(sect, &name, NULL)) != 0 || (r = sshbuf_get_u8(sect, &critical)) != 0 || (r = sshbuf_froms(sect, &value)) != 0) { debug_fr(r, "parse"); error("KRL has invalid extension section"); r = SSH_ERR_INVALID_FORMAT; goto out; } if (sshbuf_len(sect) != 0) { error("KRL has invalid extension section: trailing data"); r = SSH_ERR_INVALID_FORMAT; goto out; } debug_f("extension %s critical %u len %zu", name, critical, sshbuf_len(value)); /* no extensions are currently supported */ if (critical) { error("KRL contains unsupported critical section \"%s\"", name); r = SSH_ERR_FEATURE_UNSUPPORTED; goto out; } /* success */ r = 0; out: free(name); sshbuf_free(value); return r; } /* Attempt to parse a KRL */ int ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp) { struct sshbuf *copy = NULL, *sect = NULL; struct ssh_krl *krl = NULL; char timestamp[64]; int r = SSH_ERR_INTERNAL_ERROR; u_char type; u_int format_version; *krlp = NULL; /* KRL must begin with magic string */ if ((r = sshbuf_cmp(buf, 0, KRL_MAGIC, sizeof(KRL_MAGIC) - 1)) != 0) { debug2_f("bad KRL magic header"); return SSH_ERR_KRL_BAD_MAGIC; } if ((krl = ssh_krl_init()) == NULL) { error_f("alloc failed"); goto out; } /* Don't modify buffer */ if ((copy = sshbuf_fromb(buf)) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshbuf_consume(copy, sizeof(KRL_MAGIC) - 1)) != 0 || (r = sshbuf_get_u32(copy, &format_version)) != 0) goto out; if (format_version != KRL_FORMAT_VERSION) { error_f("unsupported KRL format version %u", format_version); r = SSH_ERR_INVALID_FORMAT; goto out; } if ((r = sshbuf_get_u64(copy, &krl->krl_version)) != 0 || (r = sshbuf_get_u64(copy, &krl->generated_date)) != 0 || (r = sshbuf_get_u64(copy, &krl->flags)) != 0 || (r = sshbuf_skip_string(copy)) != 0 || (r = sshbuf_get_cstring(copy, &krl->comment, NULL)) != 0) { error_fr(r, "parse KRL header"); goto out; } format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); debug("KRL version %llu generated at %s%s%s", (long long unsigned)krl->krl_version, timestamp, *krl->comment ? ": " : "", krl->comment); /* Parse and load the KRL sections. */ while (sshbuf_len(copy) > 0) { sshbuf_free(sect); sect = NULL; if ((r = sshbuf_get_u8(copy, &type)) != 0 || (r = sshbuf_froms(copy, §)) != 0) goto out; KRL_DBG(("section 0x%02x", type)); switch (type) { case KRL_SECTION_CERTIFICATES: if ((r = parse_revoked_certs(sect, krl)) != 0) goto out; break; case KRL_SECTION_EXPLICIT_KEY: if ((r = blob_section(sect, &krl->revoked_keys, 0)) != 0) goto out; break; case KRL_SECTION_FINGERPRINT_SHA1: if ((r = blob_section(sect, &krl->revoked_sha1s, 20)) != 0) goto out; break; case KRL_SECTION_FINGERPRINT_SHA256: if ((r = blob_section(sect, &krl->revoked_sha256s, 32)) != 0) goto out; break; case KRL_SECTION_EXTENSION: if ((r = extension_section(sect, krl)) != 0) goto out; break; case KRL_SECTION_SIGNATURE: /* Handled above, but still need to stay in synch */ sshbuf_free(sect); sect = NULL; if ((r = sshbuf_skip_string(copy)) != 0) goto out; break; default: error("Unsupported KRL section %u", type); r = SSH_ERR_INVALID_FORMAT; goto out; } if (sect != NULL && sshbuf_len(sect) > 0) { error("KRL section contains unparsed data"); r = SSH_ERR_INVALID_FORMAT; goto out; } } /* Success */ *krlp = krl; r = 0; out: if (r != 0) ssh_krl_free(krl); sshbuf_free(copy); sshbuf_free(sect); return r; } /* Checks certificate serial number and key ID revocation */ static int is_cert_revoked(const struct sshkey *key, struct revoked_certs *rc) { struct revoked_serial rs, *ers; struct revoked_key_id rki, *erki; /* Check revocation by cert key ID */ memset(&rki, 0, sizeof(rki)); rki.key_id = key->cert->key_id; erki = RB_FIND(revoked_key_id_tree, &rc->revoked_key_ids, &rki); if (erki != NULL) { KRL_DBG(("revoked by key ID")); return SSH_ERR_KEY_REVOKED; } /* * Zero serials numbers are ignored (it's the default when the * CA doesn't specify one). */ if (key->cert->serial == 0) return 0; memset(&rs, 0, sizeof(rs)); rs.lo = rs.hi = key->cert->serial; ers = RB_FIND(revoked_serial_tree, &rc->revoked_serials, &rs); if (ers != NULL) { KRL_DBG(("revoked serial %llu matched %llu:%llu", key->cert->serial, ers->lo, ers->hi)); return SSH_ERR_KEY_REVOKED; } return 0; } /* Checks whether a given key/cert is revoked. Does not check its CA */ static int is_key_revoked(struct ssh_krl *krl, const struct sshkey *key) { struct revoked_blob rb, *erb; struct revoked_certs *rc; int r; /* Check explicitly revoked hashes first */ memset(&rb, 0, sizeof(rb)); if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA1, &rb.blob, &rb.len)) != 0) return r; erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha1s, &rb); free(rb.blob); if (erb != NULL) { KRL_DBG(("revoked by key SHA1")); return SSH_ERR_KEY_REVOKED; } memset(&rb, 0, sizeof(rb)); if ((r = sshkey_fingerprint_raw(key, SSH_DIGEST_SHA256, &rb.blob, &rb.len)) != 0) return r; erb = RB_FIND(revoked_blob_tree, &krl->revoked_sha256s, &rb); free(rb.blob); if (erb != NULL) { KRL_DBG(("revoked by key SHA256")); return SSH_ERR_KEY_REVOKED; } /* Next, explicit keys */ memset(&rb, 0, sizeof(rb)); if ((r = plain_key_blob(key, &rb.blob, &rb.len)) != 0) return r; erb = RB_FIND(revoked_blob_tree, &krl->revoked_keys, &rb); free(rb.blob); if (erb != NULL) { KRL_DBG(("revoked by explicit key")); return SSH_ERR_KEY_REVOKED; } if (!sshkey_is_cert(key)) return 0; /* Check cert revocation for the specified CA */ if ((r = revoked_certs_for_ca_key(krl, key->cert->signature_key, &rc, 0)) != 0) return r; if (rc != NULL) { if ((r = is_cert_revoked(key, rc)) != 0) return r; } /* Check cert revocation for the wildcard CA */ if ((r = revoked_certs_for_ca_key(krl, NULL, &rc, 0)) != 0) return r; if (rc != NULL) { if ((r = is_cert_revoked(key, rc)) != 0) return r; } KRL_DBG(("%llu no match", key->cert->serial)); return 0; } int ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key) { int r; KRL_DBG(("checking key")); if ((r = is_key_revoked(krl, key)) != 0) return r; if (sshkey_is_cert(key)) { debug2_f("checking CA key"); if ((r = is_key_revoked(krl, key->cert->signature_key)) != 0) return r; } KRL_DBG(("key okay")); return 0; } int ssh_krl_file_contains_key(const char *path, const struct sshkey *key) { struct sshbuf *krlbuf = NULL; struct ssh_krl *krl = NULL; int oerrno = 0, r; if (path == NULL) return 0; if ((r = sshbuf_load_file(path, &krlbuf)) != 0) { oerrno = errno; goto out; } if ((r = ssh_krl_from_blob(krlbuf, &krl)) != 0) goto out; debug2_f("checking KRL %s", path); r = ssh_krl_check_key(krl, key); out: sshbuf_free(krlbuf); ssh_krl_free(krl); if (r != 0) errno = oerrno; return r; } int krl_dump(struct ssh_krl *krl, FILE *f) { struct sshkey *key = NULL; struct revoked_blob *rb; struct revoked_certs *rc; struct revoked_serial *rs; struct revoked_key_id *rki; int r, ret = 0; char *fp, timestamp[64]; /* Try to print in a KRL spec-compatible format */ format_timestamp(krl->generated_date, timestamp, sizeof(timestamp)); fprintf(f, "# KRL version %llu\n", (unsigned long long)krl->krl_version); fprintf(f, "# Generated at %s\n", timestamp); if (krl->comment != NULL && *krl->comment != '\0') { r = INT_MAX; asmprintf(&fp, INT_MAX, &r, "%s", krl->comment); fprintf(f, "# Comment: %s\n", fp); free(fp); } fputc('\n', f); RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_keys) { if ((r = sshkey_from_blob(rb->blob, rb->len, &key)) != 0) { ret = SSH_ERR_INVALID_FORMAT; error_r(r, "parse KRL key"); continue; } if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) { ret = SSH_ERR_INVALID_FORMAT; error("sshkey_fingerprint failed"); continue; } fprintf(f, "hash: %s # %s\n", fp, sshkey_ssh_name(key)); free(fp); free(key); } RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha256s) { fp = tohex(rb->blob, rb->len); fprintf(f, "hash: SHA256:%s\n", fp); free(fp); } RB_FOREACH(rb, revoked_blob_tree, &krl->revoked_sha1s) { /* * There is not KRL spec keyword for raw SHA1 hashes, so * print them as comments. */ fp = tohex(rb->blob, rb->len); fprintf(f, "# hash SHA1:%s\n", fp); free(fp); } TAILQ_FOREACH(rc, &krl->revoked_certs, entry) { fputc('\n', f); if (rc->ca_key == NULL) fprintf(f, "# Wildcard CA\n"); else { if ((fp = sshkey_fingerprint(rc->ca_key, SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL) { ret = SSH_ERR_INVALID_FORMAT; error("sshkey_fingerprint failed"); continue; } fprintf(f, "# CA key %s %s\n", sshkey_ssh_name(rc->ca_key), fp); free(fp); } RB_FOREACH(rs, revoked_serial_tree, &rc->revoked_serials) { if (rs->lo == rs->hi) { fprintf(f, "serial: %llu\n", (unsigned long long)rs->lo); } else { fprintf(f, "serial: %llu-%llu\n", (unsigned long long)rs->lo, (unsigned long long)rs->hi); } } RB_FOREACH(rki, revoked_key_id_tree, &rc->revoked_key_ids) { /* * We don't want key IDs with embedded newlines to * mess up the display. */ r = INT_MAX; asmprintf(&fp, INT_MAX, &r, "%s", rki->key_id); fprintf(f, "id: %s\n", fp); free(fp); } } return ret; }