X-Git-Url: https://git.librecmc.org/?p=oweals%2Fucert.git;a=blobdiff_plain;f=ucert.c;h=7de4c12711e861bbf1ca0e5c26c082c3e04c832a;hp=51b421ed89ddddbd7be8ddbf83e2b6ebcf4d2042;hb=afc86f352bf7915f81e9d38949e91306542aadee;hpb=a7169f497ffa539d08ddb04d18aeb9b893203c3a

diff --git a/ucert.c b/ucert.c
index 51b421e..7de4c12 100644
--- a/ucert.c
+++ b/ucert.c
@@ -47,7 +47,23 @@ static enum {
 } cmd = CMD_NONE;
 
 static bool quiet;
+#ifndef UCERT_STRIP_MESSAGES
+#define DPRINTF(format, ...)									\
+	do {											\
+		if (!quiet)									\
+			fprintf(stderr, "%s(%d): " format, __func__, __LINE__, ## __VA_ARGS__);	\
+	} while (0)
+#else
+#define DPRINTF(format, ...) do { } while (0)
+#endif
 
+/*
+ * ucert structure
+ * |               BLOB                    |
+ * |    SIGNATURE    |       PAYLOAD       |
+ * |                 |[ BLOBMSG CONTAINER ]|
+ * |                 |[[T,i,v,e,f,pubkey ]]|
+ */
 enum cert_attr {
 	CERT_ATTR_SIGNATURE,
 	CERT_ATTR_PAYLOAD,
@@ -93,31 +109,35 @@ static const struct blobmsg_policy cert_payload_policy[CERT_PL_ATTR_MAX] = {
 	[CERT_PL_ATTR_KEY_FINGERPRINT] = { .name = "fingerprint", .type = BLOBMSG_TYPE_STRING },
 };
 
+/* list to store certificate chain at runtime */
 struct cert_object {
 	struct list_head list;
-	struct blob_attr **cert;
+	struct blob_attr *cert[CERT_ATTR_MAX];
 };
 
-static int write_file(const char *filename, void *buf, size_t len, bool append) {
+/* write buffer to file */
+static bool write_file(const char *filename, void *buf, size_t len, bool append) {
 	FILE *f;
 	size_t outlen;
 
 	f = fopen(filename, append?"a":"w");
 	if (!f)
-		return 1;
+		return false;
 
 	outlen = fwrite(buf, 1, len, f);
 	fclose(f);
 	return (outlen == len);
 }
 
+/* load certfile into list */
 static int cert_load(const char *certfile, struct list_head *chain) {
 	FILE *f;
 	struct blob_attr *certtb[CERT_ATTR_MAX];
+	struct blob_attr *bufpt;
 	struct cert_object *cobj;
 	char filebuf[CERT_BUF_LEN];
-	int ret = 0;
-	int len;
+	int ret = 0, pret = 0;
+	size_t len, pos = 0;
 
 	f = fopen(certfile, "r");
 	if (!f)
@@ -132,20 +152,64 @@ static int cert_load(const char *certfile, struct list_head *chain) {
 	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);
+	bufpt = (struct blob_attr *)filebuf;
+	do {
+		pret = blob_parse_untrusted(bufpt, len, certtb, cert_policy, CERT_ATTR_MAX);
+		if (pret <= 0)
+			/* no attributes found */
+			break;
+
+		if (pos + blob_pad_len(bufpt) > len)
+			/* blob exceeds filebuffer */
+			break;
+		else
+			pos += blob_pad_len(bufpt);
+
+		if (!certtb[CERT_ATTR_SIGNATURE])
+			/* no signature -> drop */
+			break;
+
+		cobj = calloc(1, sizeof(*cobj));
+		cobj->cert[CERT_ATTR_SIGNATURE] = blob_memdup(certtb[CERT_ATTR_SIGNATURE]);
+		if (certtb[CERT_ATTR_PAYLOAD])
+			cobj->cert[CERT_ATTR_PAYLOAD] = blob_memdup(certtb[CERT_ATTR_PAYLOAD]);
+
+		list_add_tail(&cobj->list, chain);
+		ret += pret;
+	/* repeat parsing while there is still enough remaining data in buffer */
+	} while(len > pos + sizeof(struct blob_attr) && (bufpt = blob_next(bufpt)));
 
 	return (ret <= 0);
 }
 
-static int cert_append(const char *certfile, const char *pubkeyfile, const char *sigfile) {
-	fprintf(stderr, "not implemented\n");
-	return 1;
+#ifdef UCERT_FULL
+/* append signature to certfile */
+static int cert_append(const char *certfile, const char *sigfile) {
+	FILE *fs;
+	char filebuf[CERT_BUF_LEN];
+	struct blob_buf sigbuf = {0};
+	int len;
+	int ret;
+
+	fs = fopen(sigfile, "r");
+	if (!fs)
+		return 1;
+
+	len = fread(&filebuf, 1, CERT_BUF_LEN - 1, fs);
+	ret = ferror(fs) || !feof(fs) || (len < 64);
+	fclose(fs);
+	if (ret)
+		return 1;
+
+	blob_buf_init(&sigbuf, 0);
+	blob_put(&sigbuf, CERT_ATTR_SIGNATURE, filebuf, len);
+	ret = write_file(certfile, sigbuf.head, blob_raw_len(sigbuf.head), true);
+	blob_buf_free(&sigbuf);
+	return ret;
 }
+#endif
 
+/* verify the signature of a single chain element */
 static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX],
 		       const char *pubkeyfile, const char *pubkeydir) {
 	int i;
@@ -184,6 +248,7 @@ static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX],
 	return ret;
 }
 
+/* verify cert chain (and message) */
 static int chain_verify(const char *msgfile, const char *pubkeyfile,
 			const char *pubkeydir, struct list_head *chain) {
 	struct cert_object *cobj;
@@ -191,9 +256,11 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 	struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
 	char tmpdir[] = "/tmp/ucert-XXXXXX";
 	char chainedpubkey[256] = {0};
+	char chainedfp[17] = {0};
 	char extsigfile[256] = {0};
 	int ret = 1;
 	int checkmsg = 0;
+	struct timeval tv;
 
 	if (mkdtemp(tmpdir) == NULL)
 		return errno;
@@ -201,17 +268,19 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 	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;
+	gettimeofday(&tv, NULL);
 
+	list_for_each_entry(cobj, chain, list) {
+		/* blob has payload, verify that using signature */
 		if (cobj->cert[CERT_ATTR_PAYLOAD]) {
-			struct timeval tv;
-			uint64_t validfrom;
-			uint64_t expiresat;
+			time_t validfrom;
+			time_t expiresat;
 			uint32_t certtype;
 
+			ret = cert_verify_blob(cobj->cert, chainedpubkey[0]?chainedpubkey:pubkeyfile, pubkeydir);
+			if (ret)
+				goto clean_and_return;
+
 			blobmsg_parse(cert_cont_policy,
 				      ARRAY_SIZE(cert_cont_policy),
 				      containertb,
@@ -219,7 +288,7 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 				      blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
 			if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
 				ret = 1;
-				fprintf(stderr, "no ucert in signed payload\n");
+				DPRINTF("no ucert in signed payload\n");
 				goto clean_and_return;
 			}
 			blobmsg_parse(cert_payload_policy,
@@ -233,7 +302,7 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 			    !payloadtb[CERT_PL_ATTR_EXPIRETIME] ||
 			    !payloadtb[CERT_PL_ATTR_PUBKEY]) {
 				ret = 1;
-				fprintf(stderr, "missing mandatory ucert attributes\n");
+				DPRINTF("missing mandatory ucert attributes\n");
 				goto clean_and_return;
 			}
 			certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
@@ -242,15 +311,14 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 
 			if (certtype != CERTTYPE_AUTH) {
 				ret = 2;
-				fprintf(stderr, "wrong certificate type\n");
+				DPRINTF("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");
+				DPRINTF("certificate expired\n");
 				goto clean_and_return;
 			}
 
@@ -259,7 +327,19 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 				   blobmsg_data(payloadtb[CERT_PL_ATTR_PUBKEY]),
 				   blobmsg_data_len(payloadtb[CERT_PL_ATTR_PUBKEY]),
 				   false);
+
+			if (usign_f_pubkey(chainedfp, chainedpubkey)) {
+				DPRINTF("cannot get fingerprint for chained key\n");
+				ret = 2;
+				goto clean_and_return;
+			}
+			if (pubkeydir && _usign_key_is_revoked(chainedfp, pubkeydir)) {
+				DPRINTF("key %s has been revoked!\n", chainedfp);
+				ret = 4;
+				goto clean_and_return;
+			}
 		} else {
+		/* blob doesn't have payload, verify message using signature */
 			if (msgfile) {
 				snprintf(extsigfile, sizeof(extsigfile) - 1, "%s/%s", tmpdir, "ext-sig");
 				write_file(extsigfile,
@@ -271,14 +351,14 @@ static int chain_verify(const char *msgfile, const char *pubkeyfile,
 					      pubkeydir, extsigfile, quiet);
 				unlink(extsigfile);
 			} else {
-				fprintf(stderr, "stray trailing signature without anything to verify!\n");
+				DPRINTF("stray trailing signature without anything to verify!\n");
 				ret = 1;
 			};
 		}
 	}
 
 	if (checkmsg == -1)
-		fprintf(stderr, "missing signature to verify message!\n");
+		DPRINTF("missing signature to verify message!\n");
 
 clean_and_return:
 	if (chainedpubkey[0])
@@ -287,8 +367,11 @@ clean_and_return:
 	return ret | checkmsg;
 }
 
+#ifdef UCERT_FULL
+/* dump single chain element to console */
 static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) {
 	int i;
+	char *json = NULL;
 
 	for (i = 0; i < CERT_ATTR_MAX; i++) {
 		struct blob_attr *v = cert[i];
@@ -298,50 +381,55 @@ static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) {
 
 		switch(cert_policy[i].type) {
 		case BLOB_ATTR_BINARY:
-			fprintf(stdout, "signature:\n---\n%s\n---\n", (char *) blob_data(v));
+			printf("signature:\n---\n%s---\n", (char *) blob_data(v));
 			break;
 		case BLOB_ATTR_NESTED:
-			fprintf(stdout, "payload:\n---\n%s\n---\n", blobmsg_format_json_indent(blob_data(v), false, 0));
+			json = blobmsg_format_json_indent(blob_data(v), false, 0);
+			if (!json) {
+				DPRINTF("cannot parse payload\n");
+				continue;
+			}
+			printf("payload:\n---\n%s\n---\n", json);
+			free(json);
 			break;
 		}
 	}
 }
 
+/* dump certfile to console */
 static int cert_dump(const char *certfile) {
 	struct cert_object *cobj;
 	static LIST_HEAD(certchain);
+	unsigned int count = 0;
 
 	if (cert_load(certfile, &certchain)) {
-		fprintf(stderr, "cannot parse cert\n");
+		DPRINTF("cannot parse cert\n");
 		return 1;
 	}
 
-	list_for_each_entry(cobj, &certchain, list)
+	list_for_each_entry(cobj, &certchain, list) {
+		printf("=== CHAIN ELEMENT %02u ===\n", ++count);
 		cert_dump_blob(cobj->cert);
+	}
 
 	return 0;
 }
 
+/* issue an auth certificate for pubkey */
 static int cert_issue(const char *certfile, const char *pubkeyfile, const char *seckeyfile) {
-	struct blob_buf certbuf;
-	struct blob_buf payloadbuf;
+	struct blob_buf payloadbuf = {0};
+	struct blob_buf certbuf = {0};
 	struct timeval tv;
-	struct stat st;
 	int pklen, siglen;
 	int revoker = 1;
 	void *c;
 	FILE *pkf, *sigf;
 	char pkb[512];
-	char sigb[512];
+	char sigb[1024];
 	char fname[256], sfname[256];
 	char pkfp[17];
 	char tmpdir[] = "/tmp/ucert-XXXXXX";
 
-	if (stat(certfile, &st) == 0) {
-		fprintf(stderr, "certfile %s exists, won't overwrite.\n", certfile);
-		return -1;
-	}
-
 	pkf = fopen(pubkeyfile, "r");
 	if (!pkf)
 		return -1;
@@ -391,7 +479,7 @@ static int cert_issue(const char *certfile, const char *pubkeyfile, const char *
 		if (siglen < 1)
 			return 1;
 
-		sigb[siglen-1] = '\0';
+		sigb[siglen] = '\0';
 		fclose(sigf);
 
 		unlink(fname);
@@ -401,7 +489,10 @@ static int cert_issue(const char *certfile, const char *pubkeyfile, const char *
 		blob_put(&certbuf, CERT_ATTR_SIGNATURE, sigb, siglen);
 		blob_put(&certbuf, CERT_ATTR_PAYLOAD, blob_data(payloadbuf.head), blob_len(payloadbuf.head));
 		snprintf(fname, sizeof(fname) - 1, "%s%s", certfile, revoker?".revoke":"");
-		write_file(fname, certbuf.head, blob_raw_len(certbuf.head), false);
+		write_file(fname, certbuf.head, blob_raw_len(certbuf.head), true);
+		blob_buf_free(&certbuf);
+		blob_buf_free(&payloadbuf);
+
 		revoker--;
 	}
 
@@ -409,103 +500,234 @@ static int cert_issue(const char *certfile, const char *pubkeyfile, const char *
 
 	return 0;
 }
+#endif
 
-static int cert_process_revoker(const char *certfile) {
-	fprintf(stderr, "not implemented\n");
-	return 1;
+/* process revoker certificate */
+static int cert_process_revoker(const char *certfile, const char *pubkeydir) {
+	static LIST_HEAD(certchain);
+	struct cert_object *cobj;
+	struct blob_attr *containertb[CERT_CT_ATTR_MAX];
+	struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
+	struct stat st;
+	struct timeval tv;
+	time_t validfrom;
+	enum certtype_id certtype;
+	char *fingerprint;
+	char rfname[512];
+
+	int ret = -1;
+
+	if (cert_load(certfile, &certchain)) {
+		DPRINTF("cannot parse cert\n");
+		return 1;
+	}
+
+	gettimeofday(&tv, NULL);
+
+	list_for_each_entry(cobj, &certchain, list) {
+		if (!cobj->cert[CERT_ATTR_PAYLOAD])
+			return 2;
+
+		/* blob has payload, verify that using signature */
+		ret = cert_verify_blob(cobj->cert, NULL, pubkeydir);
+		if (ret)
+			return ret;
+
+		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]) {
+			DPRINTF("no ucert in signed payload\n");
+			return 2;
+		}
+
+		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_KEY_FINGERPRINT]) {
+			DPRINTF("missing mandatory ucert attributes\n");
+			return 2;
+		}
+
+		certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
+		validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
+		fingerprint = blobmsg_get_string(payloadtb[CERT_PL_ATTR_KEY_FINGERPRINT]);
+
+		if (certtype != CERTTYPE_REVOKE) {
+			DPRINTF("wrong certificate type\n");
+			return 2;
+		}
+
+		if (tv.tv_sec < validfrom) {
+			return 3;
+		}
+
+		snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
+		/* check if entry in pubkeydir exists */
+		if (stat(rfname, &st) == 0) {
+			if (_usign_key_is_revoked(fingerprint, pubkeydir)) {
+				DPRINTF("existing revoker deadlink for key %s\n", fingerprint);
+				continue;
+			};
+
+			/* remove any other entry */
+			if (unlink(rfname))
+				return -1;
+		}
+
+		ret = symlink(".revoked.", rfname);
+		if (ret)
+			return ret;
+
+		DPRINTF("created revoker deadlink for key %s\n", fingerprint);
+	};
+
+	return ret;
 }
 
+/* load and verify certfile (and message) */
 static int cert_verify(const char *certfile, const char *pubkeyfile, const char *pubkeydir, const char *msgfile) {
 	static LIST_HEAD(certchain);
 
 	if (cert_load(certfile, &certchain)) {
-		fprintf(stderr, "cannot parse cert\n");
+		DPRINTF("cannot parse cert\n");
 		return 1;
 	}
 
 	return chain_verify(msgfile, pubkeyfile, pubkeydir, &certchain);
 }
 
+/* output help */
 static int usage(const char *cmd)
 {
+#ifndef UCERT_STRIP_MESSAGES
 	fprintf(stderr,
 		"Usage: %s <command> <options>\n"
 		"Commands:\n"
-		"  -A:			append (needs -c and -p and/or -x)\n"
-		"  -D:			dump\n"
+#ifdef UCERT_FULL
+		"  -A:			append signature (needs -c and -x)\n"
+		"  -D:			dump (needs -c)\n"
 		"  -I:			issue cert and revoker (needs -c and -p and -s)\n"
-		"  -R:			process revoker certificate (needs -c)\n"
-		"  -V:			verify (needs -c and -p|-P)\n"
+#endif /* UCERT_FULL */
+		"  -R:			process revoker certificate (needs -c and -P)\n"
+		"  -V:			verify (needs -c and -p|-P, may have -m)\n"
 		"Options:\n"
 		"  -c <file>:		certificate file\n"
 		"  -m <file>:		message file (verify only)\n"
 		"  -p <file>:		public key file\n"
 		"  -P <path>:		public key directory (verify only)\n"
 		"  -q:			quiet (do not print verification result, use return code only)\n"
+#ifdef UCERT_FULL
 		"  -s <file>:		secret key file (issue only)\n"
-		"  -x <file>:		signature file\n"
+		"  -x <file>:		signature file (append only)\n"
+#endif /* UCERT_FULL */
 		"\n",
 		cmd);
+#endif /* UCERT_STRIP_MESSAGES */
 	return 1;
 }
 
+/* parse command line options and call functions */
 int main(int argc, char *argv[]) {
 	int ch;
 	const char *msgfile = NULL;
-	const char *sigfile = NULL;
 	const char *pubkeyfile = NULL;
 	const char *pubkeydir = NULL;
 	const char *certfile = NULL;
+#ifdef UCERT_FULL
+	const char *sigfile = NULL;
 	const char *seckeyfile = NULL;
+#endif
 
 	quiet = false;
-	while ((ch = getopt(argc, argv, "ADIRVc:m:p:P:qs:x:")) != -1) {
+	while ((ch = getopt(argc, argv,
+		"RVc:m:p:P:q"
+#ifdef UCERT_FULL
+		"ADIs:x:"
+#endif
+	       )) != -1) {
 		switch (ch) {
+#ifdef UCERT_FULL
 		case 'A':
+			if (cmd != CMD_NONE)
+				return usage(argv[0]);
 			cmd = CMD_APPEND;
 			break;
 		case 'D':
+			if (cmd != CMD_NONE)
+				return usage(argv[0]);
 			cmd = CMD_DUMP;
 			break;
 		case 'I':
+			if (cmd != CMD_NONE)
+				return usage(argv[0]);
 			cmd = CMD_ISSUE;
 			break;
+#endif
 		case 'R':
+			if (cmd != CMD_NONE)
+				return usage(argv[0]);
 			cmd = CMD_REVOKE;
 			break;
 		case 'V':
+			if (cmd != CMD_NONE)
+				return usage(argv[0]);
 			cmd = CMD_VERIFY;
 			break;
 		case 'c':
+			if (certfile || cmd == CMD_NONE)
+				return usage(argv[0]);
 			certfile = optarg;
 			break;
 		case 'm':
+			if (msgfile || cmd != CMD_VERIFY)
+				return usage(argv[0]);
 			msgfile = optarg;
 			break;
 		case 'p':
+			if (pubkeyfile || (cmd != CMD_VERIFY && cmd != CMD_ISSUE) || cmd == CMD_NONE)
+				return usage(argv[0]);
 			pubkeyfile = optarg;
 			break;
 		case 'P':
+			if (pubkeydir || (cmd != CMD_VERIFY && cmd != CMD_REVOKE) || cmd == CMD_NONE)
+				return usage(argv[0]);
 			pubkeydir = optarg;
 			break;
-		case 's':
-			seckeyfile = optarg;
-			break;
 		case 'q':
+			if (quiet)
+				return usage(argv[0]);
 			quiet = true;
 			break;
+#ifdef UCERT_FULL
+		case 's':
+			if (seckeyfile || cmd != CMD_ISSUE || cmd == CMD_NONE)
+				return usage(argv[0]);
+			seckeyfile = optarg;
+			break;
 		case 'x':
+			if (sigfile || cmd != CMD_APPEND || cmd == CMD_NONE)
+				return usage(argv[0]);
 			sigfile = optarg;
 			break;
+#endif
 		default:
 			return usage(argv[0]);
 		}
 	}
 
 	switch (cmd) {
+#ifdef UCERT_FULL
 	case CMD_APPEND:
-		if (certfile && (pubkeyfile || sigfile))
-			return cert_append(certfile, pubkeyfile, sigfile);
+		if (certfile && sigfile)
+			return cert_append(certfile, sigfile);
 		else
 			return usage(argv[0]);
 	case CMD_DUMP:
@@ -518,9 +740,10 @@ int main(int argc, char *argv[]) {
 			return cert_issue(certfile, pubkeyfile, seckeyfile);
 		else
 			return usage(argv[0]);
+#endif
 	case CMD_REVOKE:
-		if (certfile)
-			return cert_process_revoker(certfile);
+		if (certfile && pubkeydir)
+			return cert_process_revoker(certfile, pubkeydir);
 		else
 			return usage(argv[0]);
 	case CMD_VERIFY:
@@ -528,7 +751,7 @@ int main(int argc, char *argv[]) {
 			return cert_verify(certfile, pubkeyfile, pubkeydir, msgfile);
 		else
 			return usage(argv[0]);
-	case CMD_NONE:
+	default:
 		return usage(argv[0]);
 	}