From: Daniel Golle Date: Thu, 7 Jun 2018 00:17:28 +0000 (+0200) Subject: implement chain and message verify X-Git-Url: https://git.librecmc.org/?p=oweals%2Fucert.git;a=commitdiff_plain;h=a7169f497ffa539d08ddb04d18aeb9b893203c3a;ds=sidebyside implement chain and message verify Signed-off-by: Daniel Golle This work was sponsored by WIO (wiowireless.com) --- diff --git a/ucert.c b/ucert.c index 6a83053..51b421e 100644 --- a/ucert.c +++ b/ucert.c @@ -59,6 +59,15 @@ static const struct blob_attr_info cert_policy[CERT_ATTR_MAX] = { [CERT_ATTR_PAYLOAD] = { .type = BLOB_ATTR_NESTED }, }; +enum cert_cont_attr { + CERT_CT_ATTR_PAYLOAD, + CERT_CT_ATTR_MAX +}; + +static const struct blobmsg_policy cert_cont_policy[CERT_CT_ATTR_MAX] = { + [CERT_CT_ATTR_PAYLOAD] = { .name = "ucert", .type = BLOBMSG_TYPE_TABLE }, +}; + enum cert_payload_attr { CERT_PL_ATTR_CERTTYPE, CERT_PL_ATTR_CERTID, @@ -115,16 +124,20 @@ static int cert_load(const char *certfile, struct list_head *chain) { return 1; len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f); + if (len < 64) + return 1; + ret = ferror(f) || !feof(f); fclose(f); if (ret) return 1; + + /* TODO: read more than one blob from file */ ret = blob_parse(filebuf, certtb, cert_policy, CERT_ATTR_MAX); cobj = calloc(1, sizeof(*cobj)); cobj->cert = &certtb; list_add_tail(&cobj->list, chain); - fprintf(stderr, "blob_parse return %d\n", ret); return (ret <= 0); } @@ -133,6 +146,147 @@ static int cert_append(const char *certfile, const char *pubkeyfile, const char return 1; } +static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX], + const char *pubkeyfile, const char *pubkeydir) { + int i; + char msgfname[256], sigfname[256]; + int ret; + char tmpdir[] = "/tmp/ucert-XXXXXX"; + + if (mkdtemp(tmpdir) == NULL) + return errno; + + snprintf(msgfname, sizeof(msgfname) - 1, "%s/%s", tmpdir, "payload"); + snprintf(sigfname, sizeof(sigfname) - 1, "%s/%s", tmpdir, "payload.sig"); + + for (i = 0; i < CERT_ATTR_MAX; i++) { + struct blob_attr *v = cert[i]; + + if (!v) + break; + + switch(cert_policy[i].type) { + case BLOB_ATTR_BINARY: + write_file(sigfname, blob_data(v), blob_len(v), false); + break; + case BLOB_ATTR_NESTED: + write_file(msgfname, blob_data(v), blob_len(v), false); + break; + } + } + + ret = usign_v(msgfname, pubkeyfile, pubkeydir, sigfname, quiet); + + unlink(msgfname); + unlink(sigfname); + rmdir(tmpdir); + + return ret; +} + +static int chain_verify(const char *msgfile, const char *pubkeyfile, + const char *pubkeydir, struct list_head *chain) { + struct cert_object *cobj; + struct blob_attr *containertb[CERT_CT_ATTR_MAX]; + struct blob_attr *payloadtb[CERT_PL_ATTR_MAX]; + char tmpdir[] = "/tmp/ucert-XXXXXX"; + char chainedpubkey[256] = {0}; + char extsigfile[256] = {0}; + int ret = 1; + int checkmsg = 0; + + if (mkdtemp(tmpdir) == NULL) + return errno; + + if (msgfile) + checkmsg = -1; + + list_for_each_entry(cobj, chain, list) { + ret = cert_verify_blob(cobj->cert, chainedpubkey[0]?chainedpubkey:pubkeyfile, pubkeydir); + if (ret) + goto clean_and_return; + + if (cobj->cert[CERT_ATTR_PAYLOAD]) { + struct timeval tv; + uint64_t validfrom; + uint64_t expiresat; + uint32_t certtype; + + blobmsg_parse(cert_cont_policy, + ARRAY_SIZE(cert_cont_policy), + containertb, + blob_data(cobj->cert[CERT_ATTR_PAYLOAD]), + blob_len(cobj->cert[CERT_ATTR_PAYLOAD])); + if (!containertb[CERT_CT_ATTR_PAYLOAD]) { + ret = 1; + fprintf(stderr, "no ucert in signed payload\n"); + goto clean_and_return; + } + blobmsg_parse(cert_payload_policy, + ARRAY_SIZE(cert_payload_policy), + payloadtb, + blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]), + blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD])); + + if (!payloadtb[CERT_PL_ATTR_CERTTYPE] || + !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] || + !payloadtb[CERT_PL_ATTR_EXPIRETIME] || + !payloadtb[CERT_PL_ATTR_PUBKEY]) { + ret = 1; + fprintf(stderr, "missing mandatory ucert attributes\n"); + goto clean_and_return; + } + certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]); + validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]); + expiresat = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_EXPIRETIME]); + + if (certtype != CERTTYPE_AUTH) { + ret = 2; + fprintf(stderr, "wrong certificate type\n"); + goto clean_and_return; + } + + gettimeofday(&tv, NULL); + if (tv.tv_sec < validfrom || + tv.tv_sec >= expiresat) { + ret = 3; + fprintf(stderr, "certificate expired\n"); + goto clean_and_return; + } + + snprintf(chainedpubkey, sizeof(chainedpubkey) - 1, "%s/%s", tmpdir, "chained-pubkey"); + write_file(chainedpubkey, + blobmsg_data(payloadtb[CERT_PL_ATTR_PUBKEY]), + blobmsg_data_len(payloadtb[CERT_PL_ATTR_PUBKEY]), + false); + } else { + if (msgfile) { + snprintf(extsigfile, sizeof(extsigfile) - 1, "%s/%s", tmpdir, "ext-sig"); + write_file(extsigfile, + blob_data(cobj->cert[CERT_ATTR_SIGNATURE]), + blob_len(cobj->cert[CERT_ATTR_SIGNATURE]), + false); + checkmsg = ret = usign_v(msgfile, + chainedpubkey[0]?chainedpubkey:pubkeyfile, + pubkeydir, extsigfile, quiet); + unlink(extsigfile); + } else { + fprintf(stderr, "stray trailing signature without anything to verify!\n"); + ret = 1; + }; + } + } + + if (checkmsg == -1) + fprintf(stderr, "missing signature to verify message!\n"); + +clean_and_return: + if (chainedpubkey[0]) + unlink(chainedpubkey); + rmdir(tmpdir); + return ret | checkmsg; +} + static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) { int i; @@ -144,10 +298,10 @@ static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) { switch(cert_policy[i].type) { case BLOB_ATTR_BINARY: - fprintf(stdout, "signature: %s\n", blob_data(v)); + fprintf(stdout, "signature:\n---\n%s\n---\n", (char *) blob_data(v)); break; case BLOB_ATTR_NESTED: - fprintf(stdout, "payload:\n%s\n", blobmsg_format_json(blob_data(v), false)); + fprintf(stdout, "payload:\n---\n%s\n---\n", blobmsg_format_json_indent(blob_data(v), false, 0)); break; } } @@ -176,7 +330,6 @@ static int cert_issue(const char *certfile, const char *pubkeyfile, const char * int pklen, siglen; int revoker = 1; void *c; - FILE *pkf, *sigf; char pkb[512]; char sigb[512]; @@ -194,7 +347,7 @@ static int cert_issue(const char *certfile, const char *pubkeyfile, const char * return -1; pklen = fread(pkb, 1, 512, pkf); - pkb[pklen - 1] = '\0'; + pkb[pklen] = '\0'; if (pklen < 32) return -1; @@ -263,8 +416,14 @@ static int cert_process_revoker(const char *certfile) { } static int cert_verify(const char *certfile, const char *pubkeyfile, const char *pubkeydir, const char *msgfile) { - fprintf(stderr, "not implemented\n"); - return 1; + static LIST_HEAD(certchain); + + if (cert_load(certfile, &certchain)) { + fprintf(stderr, "cannot parse cert\n"); + return 1; + } + + return chain_verify(msgfile, pubkeyfile, pubkeydir, &certchain); } static int usage(const char *cmd) diff --git a/usign-exec.c b/usign-exec.c index d25f9b6..bed3db7 100644 --- a/usign-exec.c +++ b/usign-exec.c @@ -120,8 +120,6 @@ static int usign_f(char *fingerprint, const char *pubkeyfile, const char *seckey return -1; case 0: - uloop_done(); - dup2(fds[1], 1); close(0);