implement chain and message verify
authorDaniel Golle <daniel@makrotopia.org>
Thu, 7 Jun 2018 00:17:28 +0000 (02:17 +0200)
committerDaniel Golle <daniel@makrotopia.org>
Thu, 14 Jun 2018 16:51:22 +0000 (18:51 +0200)
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
This work was sponsored by WIO (wiowireless.com)

ucert.c
usign-exec.c

diff --git a/ucert.c b/ucert.c
index 6a83053..51b421e 100644 (file)
--- 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)
index d25f9b6..bed3db7 100644 (file)
@@ -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);