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Annotation of src/usr.bin/ssh/ssh-ed25519-sk.c, Revision 1.15

1.15    ! djm         1: /* $OpenBSD: ssh-ed25519-sk.c,v 1.14 2022/10/28 00:44:17 djm Exp $ */
1.1       markus      2: /*
                      3:  * Copyright (c) 2019 Markus Friedl.  All rights reserved.
                      4:  *
                      5:  * Permission to use, copy, modify, and distribute this software for any
                      6:  * purpose with or without fee is hereby granted, provided that the above
                      7:  * copyright notice and this permission notice appear in all copies.
                      8:  *
                      9:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
                     10:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     11:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
                     12:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     13:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
                     14:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
                     15:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     16:  */
1.4       djm        17:
                     18: /* #define DEBUG_SK 1 */
                     19:
1.1       markus     20: #define SSHKEY_INTERNAL
                     21: #include <sys/types.h>
                     22: #include <limits.h>
                     23:
                     24: #include "crypto_api.h"
                     25:
                     26: #include <string.h>
                     27: #include <stdarg.h>
                     28:
                     29: #include "log.h"
                     30: #include "sshbuf.h"
                     31: #include "sshkey.h"
                     32: #include "ssherr.h"
                     33: #include "ssh.h"
                     34: #include "digest.h"
                     35:
1.8       djm        36: /* Reuse some ED25519 internals */
                     37: extern struct sshkey_impl_funcs sshkey_ed25519_funcs;
                     38:
1.7       djm        39: static void
                     40: ssh_ed25519_sk_cleanup(struct sshkey *k)
                     41: {
1.8       djm        42:        sshkey_sk_cleanup(k);
                     43:        sshkey_ed25519_funcs.cleanup(k);
                     44: }
                     45:
                     46: static int
                     47: ssh_ed25519_sk_equal(const struct sshkey *a, const struct sshkey *b)
                     48: {
                     49:        if (!sshkey_sk_fields_equal(a, b))
                     50:                return 0;
                     51:        if (!sshkey_ed25519_funcs.equal(a, b))
                     52:                return 0;
                     53:        return 1;
1.7       djm        54: }
                     55:
1.9       djm        56: static int
                     57: ssh_ed25519_sk_serialize_public(const struct sshkey *key, struct sshbuf *b,
1.12      djm        58:     enum sshkey_serialize_rep opts)
1.9       djm        59: {
                     60:        int r;
                     61:
1.12      djm        62:        if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
1.9       djm        63:                return r;
                     64:        if ((r = sshkey_serialize_sk(key, b)) != 0)
                     65:                return r;
                     66:
                     67:        return 0;
                     68: }
                     69:
1.11      djm        70: static int
1.14      djm        71: ssh_ed25519_sk_serialize_private(const struct sshkey *key, struct sshbuf *b,
                     72:     enum sshkey_serialize_rep opts)
                     73: {
                     74:        int r;
                     75:
                     76:        if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
                     77:                return r;
                     78:        if ((r = sshkey_serialize_private_sk(key, b)) != 0)
                     79:                return r;
                     80:
                     81:        return 0;
                     82: }
                     83:
                     84: static int
1.11      djm        85: ssh_ed25519_sk_copy_public(const struct sshkey *from, struct sshkey *to)
                     86: {
                     87:        int r;
                     88:
                     89:        if ((r = sshkey_ed25519_funcs.copy_public(from, to)) != 0)
                     90:                return r;
                     91:        if ((r = sshkey_copy_public_sk(from, to)) != 0)
                     92:                return r;
                     93:        return 0;
                     94: }
                     95:
1.12      djm        96: static int
                     97: ssh_ed25519_sk_deserialize_public(const char *ktype, struct sshbuf *b,
                     98:     struct sshkey *key)
                     99: {
                    100:        int r;
                    101:
                    102:        if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
                    103:                return r;
                    104:        if ((r = sshkey_deserialize_sk(b, key)) != 0)
                    105:                return r;
                    106:        return 0;
                    107: }
                    108:
1.13      djm       109: static int
1.15    ! djm       110: ssh_ed25519_sk_deserialize_private(const char *ktype, struct sshbuf *b,
        !           111:     struct sshkey *key)
        !           112: {
        !           113:        int r;
        !           114:
        !           115:        if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
        !           116:                return r;
        !           117:        if ((r = sshkey_private_deserialize_sk(b, key)) != 0)
        !           118:                return r;
        !           119:        return 0;
        !           120: }
        !           121:
        !           122: static int
1.1       markus    123: ssh_ed25519_sk_verify(const struct sshkey *key,
1.13      djm       124:     const u_char *sig, size_t siglen,
                    125:     const u_char *data, size_t dlen, const char *alg, u_int compat,
1.3       djm       126:     struct sshkey_sig_details **detailsp)
1.1       markus    127: {
                    128:        struct sshbuf *b = NULL;
                    129:        struct sshbuf *encoded = NULL;
                    130:        char *ktype = NULL;
                    131:        const u_char *sigblob;
                    132:        const u_char *sm;
                    133:        u_char *m = NULL;
                    134:        u_char apphash[32];
                    135:        u_char msghash[32];
                    136:        u_char sig_flags;
                    137:        u_int sig_counter;
                    138:        size_t len;
                    139:        unsigned long long smlen = 0, mlen = 0;
                    140:        int r = SSH_ERR_INTERNAL_ERROR;
                    141:        int ret;
1.3       djm       142:        struct sshkey_sig_details *details = NULL;
                    143:
                    144:        if (detailsp != NULL)
                    145:                *detailsp = NULL;
1.1       markus    146:
                    147:        if (key == NULL ||
                    148:            sshkey_type_plain(key->type) != KEY_ED25519_SK ||
                    149:            key->ed25519_pk == NULL ||
1.13      djm       150:            sig == NULL || siglen == 0)
1.1       markus    151:                return SSH_ERR_INVALID_ARGUMENT;
                    152:
1.13      djm       153:        if ((b = sshbuf_from(sig, siglen)) == NULL)
1.1       markus    154:                return SSH_ERR_ALLOC_FAIL;
                    155:        if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
1.2       markus    156:            sshbuf_get_string_direct(b, &sigblob, &len) != 0 ||
                    157:            sshbuf_get_u8(b, &sig_flags) != 0 ||
                    158:            sshbuf_get_u32(b, &sig_counter) != 0) {
1.1       markus    159:                r = SSH_ERR_INVALID_FORMAT;
                    160:                goto out;
                    161:        }
1.4       djm       162: #ifdef DEBUG_SK
                    163:        fprintf(stderr, "%s: data:\n", __func__);
                    164:        /* sshbuf_dump_data(data, datalen, stderr); */
                    165:        fprintf(stderr, "%s: sigblob:\n", __func__);
                    166:        sshbuf_dump_data(sigblob, len, stderr);
                    167:        fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
                    168:            __func__, sig_flags, sig_counter);
                    169: #endif
1.1       markus    170:        if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
                    171:                r = SSH_ERR_KEY_TYPE_MISMATCH;
                    172:                goto out;
                    173:        }
                    174:        if (sshbuf_len(b) != 0) {
                    175:                r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
                    176:                goto out;
                    177:        }
                    178:        if (len > crypto_sign_ed25519_BYTES) {
                    179:                r = SSH_ERR_INVALID_FORMAT;
                    180:                goto out;
                    181:        }
                    182:        if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
                    183:            strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
1.13      djm       184:            ssh_digest_memory(SSH_DIGEST_SHA256, data, dlen,
1.1       markus    185:            msghash, sizeof(msghash)) != 0) {
                    186:                r = SSH_ERR_INVALID_ARGUMENT;
                    187:                goto out;
                    188:        }
1.4       djm       189: #ifdef DEBUG_SK
                    190:        fprintf(stderr, "%s: hashed application:\n", __func__);
                    191:        sshbuf_dump_data(apphash, sizeof(apphash), stderr);
                    192:        fprintf(stderr, "%s: hashed message:\n", __func__);
                    193:        sshbuf_dump_data(msghash, sizeof(msghash), stderr);
                    194: #endif
1.3       djm       195:        if ((details = calloc(1, sizeof(*details))) == NULL) {
                    196:                r = SSH_ERR_ALLOC_FAIL;
                    197:                goto out;
                    198:        }
                    199:        details->sk_counter = sig_counter;
                    200:        details->sk_flags = sig_flags;
1.1       markus    201:        if ((encoded = sshbuf_new()) == NULL) {
                    202:                r = SSH_ERR_ALLOC_FAIL;
                    203:                goto out;
                    204:        }
                    205:        if (sshbuf_put(encoded, sigblob, len) != 0 ||
                    206:            sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
                    207:            sshbuf_put_u8(encoded, sig_flags) != 0 ||
                    208:            sshbuf_put_u32(encoded, sig_counter) != 0 ||
                    209:            sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
                    210:                r = SSH_ERR_ALLOC_FAIL;
                    211:                goto out;
                    212:        }
1.4       djm       213: #ifdef DEBUG_SK
                    214:        fprintf(stderr, "%s: signed buf:\n", __func__);
                    215:        sshbuf_dump(encoded, stderr);
                    216: #endif
1.1       markus    217:        sm = sshbuf_ptr(encoded);
                    218:        smlen = sshbuf_len(encoded);
                    219:        mlen = smlen;
                    220:        if ((m = malloc(smlen)) == NULL) {
                    221:                r = SSH_ERR_ALLOC_FAIL;
                    222:                goto out;
                    223:        }
                    224:        if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
                    225:            key->ed25519_pk)) != 0) {
1.6       djm       226:                debug2_f("crypto_sign_ed25519_open failed: %d", ret);
1.1       markus    227:        }
                    228:        if (ret != 0 || mlen != smlen - len) {
                    229:                r = SSH_ERR_SIGNATURE_INVALID;
                    230:                goto out;
                    231:        }
                    232:        /* XXX compare 'm' and 'sm + len' ? */
                    233:        /* success */
                    234:        r = 0;
1.3       djm       235:        if (detailsp != NULL) {
                    236:                *detailsp = details;
                    237:                details = NULL;
                    238:        }
1.1       markus    239:  out:
1.5       jsg       240:        if (m != NULL)
                    241:                freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
1.3       djm       242:        sshkey_sig_details_free(details);
1.1       markus    243:        sshbuf_free(b);
                    244:        sshbuf_free(encoded);
                    245:        free(ktype);
                    246:        return r;
                    247: }
1.7       djm       248:
                    249: static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = {
                    250:        /* .size = */           NULL,
                    251:        /* .alloc = */          NULL,
                    252:        /* .cleanup = */        ssh_ed25519_sk_cleanup,
1.8       djm       253:        /* .equal = */          ssh_ed25519_sk_equal,
1.9       djm       254:        /* .ssh_serialize_public = */ ssh_ed25519_sk_serialize_public,
1.12      djm       255:        /* .ssh_deserialize_public = */ ssh_ed25519_sk_deserialize_public,
1.14      djm       256:        /* .ssh_serialize_private = */ ssh_ed25519_sk_serialize_private,
1.15    ! djm       257:        /* .ssh_deserialize_private = */ ssh_ed25519_sk_deserialize_private,
1.10      djm       258:        /* .generate = */       NULL,
1.11      djm       259:        /* .copy_public = */    ssh_ed25519_sk_copy_public,
1.13      djm       260:        /* .sign = */           NULL,
                    261:        /* .verify = */         ssh_ed25519_sk_verify,
1.7       djm       262: };
                    263:
                    264: const struct sshkey_impl sshkey_ed25519_sk_impl = {
                    265:        /* .name = */           "sk-ssh-ed25519@openssh.com",
                    266:        /* .shortname = */      "ED25519-SK",
                    267:        /* .sigalg = */         NULL,
                    268:        /* .type = */           KEY_ED25519_SK,
                    269:        /* .nid = */            0,
                    270:        /* .cert = */           0,
                    271:        /* .sigonly = */        0,
                    272:        /* .keybits = */        256,
                    273:        /* .funcs = */          &sshkey_ed25519_sk_funcs,
                    274: };
                    275:
                    276: const struct sshkey_impl sshkey_ed25519_sk_cert_impl = {
                    277:        /* .name = */           "sk-ssh-ed25519-cert-v01@openssh.com",
                    278:        /* .shortname = */      "ED25519-SK-CERT",
                    279:        /* .sigalg = */         NULL,
                    280:        /* .type = */           KEY_ED25519_SK_CERT,
                    281:        /* .nid = */            0,
                    282:        /* .cert = */           1,
                    283:        /* .sigonly = */        0,
                    284:        /* .keybits = */        256,
                    285:        /* .funcs = */          &sshkey_ed25519_sk_funcs,
                    286: };