1 files changed, 455 insertions, 0 deletions
diff --git a/src/modules/rlm_yubikey/rlm_yubikey.c b/src/modules/rlm_yubikey/rlm_yubikey.c
new file mode 100644
index 0000000..83b7655
--- /dev/null
+++ b/src/modules/rlm_yubikey/rlm_yubikey.c
@@ -0,0 +1,455 @@
+/*
+ *   This program is is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or (at
+ *   your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/**
+ * $Id$
+ * @file rlm_yubikey.c
+ * @brief Authentication for yubikey OTP tokens.
+ *
+ * @author Arran Cudbard-Bell <a.cudbardb@networkradius.com>
+ * @copyright 2013 The FreeRADIUS server project
+ * @copyright 2013 Network RADIUS <info@networkradius.com>
+ */
+RCSID("$Id$")
+
+#include "rlm_yubikey.h"
+
+/*
+ *	A mapping of configuration file names to internal variables.
+ *
+ *	Note that the string is dynamically allocated, so it MUST
+ *	be freed.  When the configuration file parse re-reads the string,
+ *	it free's the old one, and strdup's the new one, placing the pointer
+ *	to the strdup'd string into 'config.string'.  This gets around
+ *	buffer over-flows.
+ */
+
+#ifdef HAVE_YKCLIENT
+static const CONF_PARSER validation_config[] = {
+	{ "client_id", FR_CONF_OFFSET(PW_TYPE_INTEGER, rlm_yubikey_t, client_id), 0 },
+	{ "api_key", FR_CONF_OFFSET(PW_TYPE_STRING | PW_TYPE_SECRET, rlm_yubikey_t, api_key), NULL },
+	CONF_PARSER_TERMINATOR
+};
+#endif
+
+static const CONF_PARSER module_config[] = {
+	{ "id_length", FR_CONF_OFFSET(PW_TYPE_INTEGER, rlm_yubikey_t, id_len), "12" },
+	{ "split", FR_CONF_OFFSET(PW_TYPE_BOOLEAN, rlm_yubikey_t, split), "yes" },
+	{ "decrypt", FR_CONF_OFFSET(PW_TYPE_BOOLEAN, rlm_yubikey_t, decrypt), "no" },
+	{ "validate", FR_CONF_OFFSET(PW_TYPE_BOOLEAN, rlm_yubikey_t, validate), "no" },
+#ifdef HAVE_YKCLIENT
+	{ "validation", FR_CONF_POINTER(PW_TYPE_SUBSECTION, NULL), (void const *) validation_config },
+#endif
+	CONF_PARSER_TERMINATOR
+};
+
+static char const modhextab[] = "cbdefghijklnrtuv";
+static char const hextab[] = "0123456789abcdef";
+
+#define is_modhex(x) (memchr(modhextab, tolower(x), 16))
+
+/** Convert yubikey modhex to normal hex
+ *
+ * The same buffer may be passed as modhex and hex to convert the modhex in place.
+ *
+ * Modhex and hex must be the same size.
+ *
+ * @param[in] modhex data.
+ * @param[in] len of input and output buffers.
+ * @param[out] hex where to write the standard hexits.
+ * @return The number of bytes written to the output buffer, or -1 on error.
+ */
+static ssize_t modhex2hex(char const *modhex, uint8_t *hex, size_t len)
+{
+	size_t i;
+	char *c1, *c2;
+
+	for (i = 0; i < len; i++) {
+		if (modhex[i << 1] == '\0') {
+			break;
+		}
+
+		/*
+		 *	We only deal with whole bytes
+		 */
+		if (modhex[(i << 1) + 1] == '\0')
+			return -1;
+
+		if (!(c1 = memchr(modhextab, tolower((uint8_t) modhex[i << 1]), 16)) ||
+		    !(c2 = memchr(modhextab, tolower((uint8_t) modhex[(i << 1) + 1]), 16)))
+			return -1;
+
+		hex[i] = hextab[c1 - modhextab];
+		hex[i + 1] = hextab[c2 - modhextab];
+	}
+
+	return i;
+}
+
+/**
+ * @brief Convert Yubikey modhex to standard hex
+ *
+ * Example: "%{modhextohex:vvrbuctetdhc}" == "ffc1e0d3d260"
+ */
+static ssize_t modhex_to_hex_xlat(UNUSED void *instance, REQUEST *request, char const *fmt, char *out, size_t outlen)
+{
+	ssize_t len;
+
+	if (outlen < strlen(fmt)) {
+		*out = '\0';
+		return 0;
+	}
+
+	/*
+	 *	mod2hex allows conversions in place
+	 */
+	len = modhex2hex(fmt, (uint8_t *) out, strlen(fmt));
+	if (len <= 0) {
+		*out = '\0';
+		REDEBUG("Modhex string invalid");
+
+		return -1;
+	}
+
+	return len;
+}
+
+
+static int mod_bootstrap(CONF_SECTION *conf, void *instance)
+{
+	rlm_yubikey_t *inst = instance;
+
+	inst->name = cf_section_name2(conf);
+	if (!inst->name) inst->name = cf_section_name1(conf);
+
+#ifndef HAVE_YUBIKEY
+	if (inst->decrypt) {
+		cf_log_err_cs(conf, "Requires libyubikey for OTP decryption");
+		return -1;
+	}
+#endif
+
+	if (!cf_section_name2(conf)) return 0;
+
+	xlat_register("modhextohex", modhex_to_hex_xlat, NULL, inst);
+
+	return 0;
+}
+
+/*
+ *	Do any per-module initialization that is separate to each
+ *	configured instance of the module.  e.g. set up connections
+ *	to external databases, read configuration files, set up
+ *	dictionary entries, etc.
+ *
+ *	If configuration information is given in the config section
+ *	that must be referenced in later calls, store a handle to it
+ *	in *instance otherwise put a null pointer there.
+ */
+static int mod_instantiate(CONF_SECTION *conf, void *instance)
+{
+	rlm_yubikey_t *inst = instance;
+
+	if (inst->validate) {
+#ifdef HAVE_YKCLIENT
+		CONF_SECTION *cs;
+
+		cs = cf_section_sub_find(conf, "validation");
+		if (!cs) {
+			cf_log_err_cs(conf, "Missing validation section");
+			return -1;
+		}
+
+		if (rlm_yubikey_ykclient_init(cs, inst) < 0) {
+			return -1;
+		}
+#else
+		cf_log_err_cs(conf, "Requires libykclient for OTP validation against Yubicloud servers");
+		return -1;
+#endif
+	}
+
+	return 0;
+}
+
+/*
+ *	Only free memory we allocated.  The strings allocated via
+ *	cf_section_parse() do not need to be freed.
+ */
+#ifdef HAVE_YKCLIENT
+static int mod_detach(void *instance)
+{
+	rlm_yubikey_ykclient_detach((rlm_yubikey_t *) instance);
+	return 0;
+}
+#endif
+
+static int CC_HINT(nonnull) otp_string_valid(rlm_yubikey_t *inst, char const *otp, size_t len)
+{
+	size_t i;
+
+	for (i = inst->id_len; i < len; i++) {
+		if (!is_modhex(otp[i])) return -i;
+	}
+
+	return 1;
+}
+
+
+/*
+ *	Find the named user in this modules database.  Create the set
+ *	of attribute-value pairs to check and reply with for this user
+ *	from the database. The authentication code only needs to check
+ *	the password, the rest is done here.
+ */
+static rlm_rcode_t CC_HINT(nonnull) mod_authorize(void *instance, REQUEST *request)
+{
+	rlm_yubikey_t *inst = instance;
+
+	DICT_VALUE *dval;
+	char const *passcode;
+	size_t len;
+	VALUE_PAIR *vp;
+
+	/*
+	 *	Can't do yubikey auth if there's no password.
+	 */
+	if (!request->password || (request->password->da->attr != PW_USER_PASSWORD)) {
+		/*
+		 *	Don't print out debugging messages if we know
+		 *	they're useless.
+		 */
+		if (request->packet->code == PW_CODE_ACCESS_CHALLENGE) {
+			return RLM_MODULE_NOOP;
+		}
+
+		RDEBUG2("No cleartext password in the request. Can't do Yubikey authentication");
+
+		return RLM_MODULE_NOOP;
+	}
+
+	passcode = request->password->vp_strvalue;
+	len = request->password->vp_length;
+
+	/*
+	 *	Now see if the passcode is the correct length (in its raw
+	 *	modhex encoded form).
+	 *
+	 *	<public_id (6-16 bytes)> + <aes-block (32 bytes)>
+	 *
+	 */
+	if (len > (inst->id_len + YUBIKEY_TOKEN_LEN)) {
+		/* May be a concatenation, check the last 32 bytes are modhex */
+		if (inst->split) {
+			char const *otp;
+			char *password;
+			size_t password_len;
+			int ret;
+
+			password_len = (len - (inst->id_len + YUBIKEY_TOKEN_LEN));
+			otp = passcode + password_len;
+			ret = otp_string_valid(inst, otp, (inst->id_len + YUBIKEY_TOKEN_LEN));
+			if (ret <= 0) {
+				if (RDEBUG_ENABLED3) {
+					RDMARKER(otp, -ret, "User-Password (aes-block) value contains non modhex chars");
+				} else {
+					RDEBUG("User-Password (aes-block) value contains non modhex chars");
+				}
+				return RLM_MODULE_NOOP;
+			}
+
+			/*
+			 *	Insert a new request attribute just containing the OTP
+			 *	portion.
+			 */
+			vp = pair_make_request("Yubikey-OTP", otp, T_OP_SET);
+			if (!vp) {
+				REDEBUG("Failed creating 'Yubikey-OTP' attribute");
+				return RLM_MODULE_FAIL;
+			}
+
+			/*
+			 *	Replace the existing string buffer for the password
+			 *	attribute with one just containing the password portion.
+			 */
+			MEM(password = talloc_array(request->password, char, password_len + 1));
+			strlcpy(password, passcode, password_len + 1);
+			fr_pair_value_strsteal(request->password, password);
+
+			RINDENT();
+			if (RDEBUG_ENABLED3) {
+				RDEBUG3("&request:Yubikey-OTP := '%s'", vp->vp_strvalue);
+				RDEBUG3("&request:User-Password := '%s'", request->password->vp_strvalue);
+			} else {
+				RDEBUG2("&request:Yubikey-OTP := <<< secret >>>");
+				RDEBUG2("&request:User-Password := <<< secret >>>");
+			}
+			REXDENT();
+			/*
+			 *	So the ID split code works on the non password portion.
+			 */
+			passcode = vp->vp_strvalue;
+		}
+	} else if (len < (inst->id_len + YUBIKEY_TOKEN_LEN)) {
+		RDEBUG2("User-Password value is not the correct length, expected at least %u bytes, got %zu bytes",
+			inst->id_len + YUBIKEY_TOKEN_LEN, len);
+		return RLM_MODULE_NOOP;
+	} else {
+		int ret;
+
+		ret = otp_string_valid(inst, passcode, (inst->id_len + YUBIKEY_TOKEN_LEN));
+		if (ret <= 0) {
+			if (RDEBUG_ENABLED3) {
+				RDMARKER(passcode, -ret, "User-Password (aes-block) value contains non modhex chars");
+			} else {
+				RDEBUG("User-Password (aes-block) value contains non modhex chars");
+			}
+			return RLM_MODULE_NOOP;
+		}
+	}
+
+	dval = dict_valbyname(PW_AUTH_TYPE, 0, inst->name);
+	if (dval) {
+		vp = radius_pair_create(request, &request->config, PW_AUTH_TYPE, 0);
+		vp->vp_integer = dval->value;
+	}
+
+	/*
+	 *	Split out the Public ID in case another module in authorize
+	 *	needs to verify it's associated with the user.
+	 *
+	 *	It's left up to the user if they want to decode it or not.
+	 */
+	if (inst->id_len) {
+		vp = fr_pair_make(request->packet, &request->packet->vps, "Yubikey-Public-ID", NULL, T_OP_SET);
+		if (!vp) {
+			REDEBUG("Failed creating Yubikey-Public-ID");
+
+			return RLM_MODULE_FAIL;
+		}
+
+		fr_pair_value_bstrncpy(vp, passcode, inst->id_len);
+	}
+
+	return RLM_MODULE_OK;
+}
+
+
+/*
+ *	Authenticate the user with the given password.
+ */
+static rlm_rcode_t CC_HINT(nonnull) mod_authenticate(void *instance, REQUEST *request)
+{
+	rlm_rcode_t rcode = RLM_MODULE_NOOP;
+	rlm_yubikey_t *inst = instance;
+	char const *passcode = NULL;
+	DICT_ATTR const *da;
+	VALUE_PAIR const *vp;
+	size_t len;
+	int ret;
+
+	da = dict_attrbyname("Yubikey-OTP");
+	if (!da) {
+		RDEBUG2("No Yubikey-OTP attribute defined, falling back to User-Password");
+		goto user_password;
+	}
+
+	vp = fr_pair_find_by_da(request->packet->vps, da, TAG_ANY);
+	if (vp) {
+		passcode = vp->vp_strvalue;
+		len = vp->vp_length;
+	} else {
+		RDEBUG2("No Yubikey-OTP attribute found, falling back to User-Password");
+	user_password:
+		/*
+		 *	Can't do yubikey auth if there's no password.
+		 */
+		if (!request->password || (request->password->da->attr != PW_USER_PASSWORD)) {
+			REDEBUG("No User-Password in the request. Can't do Yubikey authentication");
+			return RLM_MODULE_INVALID;
+		}
+
+		vp = request->password;
+		passcode = request->password->vp_strvalue;
+		len = request->password->vp_length;
+	}
+
+	/*
+	 *	Verify the passcode is the correct length (in its raw
+	 *	modhex encoded form).
+	 *
+	 *	<public_id (6-16 bytes)> + <aes-block (32 bytes)>
+	 */
+	if (len != (inst->id_len + YUBIKEY_TOKEN_LEN)) {
+		REDEBUG("%s value is not the correct length, expected bytes %u, got bytes %zu",
+			vp->da->name, inst->id_len + YUBIKEY_TOKEN_LEN, len);
+		return RLM_MODULE_INVALID;
+	}
+
+	ret = otp_string_valid(inst, passcode, (inst->id_len + YUBIKEY_TOKEN_LEN));
+	if (ret <= 0) {
+		if (RDEBUG_ENABLED3) {
+			REMARKER(passcode, -ret, "Passcode (aes-block) value contains non modhex chars");
+		} else {
+			RERROR("Passcode (aes-block) value contains non modhex chars");
+		}
+		return RLM_MODULE_INVALID;
+	}
+
+#ifdef HAVE_YUBIKEY
+	if (inst->decrypt) {
+		rcode = rlm_yubikey_decrypt(inst, request, passcode);
+		if (rcode != RLM_MODULE_OK) {
+			return rcode;
+		}
+		/* Fall-Through to doing ykclient auth in addition to local auth */
+	}
+#endif
+
+#ifdef HAVE_YKCLIENT
+	if (inst->validate) {
+		return rlm_yubikey_validate(inst, request, passcode);
+	}
+#endif
+	return rcode;
+}
+
+/*
+ *	The module name should be the only globally exported symbol.
+ *	That is, everything else should be 'static'.
+ *
+ *	If the module needs to temporarily modify it's instantiation
+ *	data, the type should be changed to RLM_TYPE_THREAD_UNSAFE.
+ *	The server will then take care of ensuring that the module
+ *	is single-threaded.
+ */
+extern module_t rlm_yubikey;
+module_t rlm_yubikey = {
+	.magic		= RLM_MODULE_INIT,
+	.name		= "yubikey",
+	.type		= RLM_TYPE_THREAD_SAFE,
+	.inst_size	= sizeof(rlm_yubikey_t),
+	.config		= module_config,
+	.bootstrap	= mod_bootstrap,
+	.instantiate	= mod_instantiate,
+#ifdef HAVE_YKCLIENT
+	.detach		= mod_detach,
+#endif
+	.methods = {
+		[MOD_AUTHENTICATE]	= mod_authenticate,
+		[MOD_AUTHORIZE]		= mod_authorize
+	},
+};