Adding upstream version 1:2.3.21+dfsg1.upstream/1%2.3.21+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 592 insertions, 0 deletions

diff --git a/src/auth/mech-digest-md5.c b/src/auth/mech-digest-md5.c
new file mode 100644
index 0000000..d7f4383
--- /dev/null
+++ b/src/auth/mech-digest-md5.c
@@ -0,0 +1,592 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+/* Digest-MD5 SASL authentication, see RFC-2831 */
+
+#include "auth-common.h"
+#include "base64.h"
+#include "buffer.h"
+#include "hex-binary.h"
+#include "mech-digest-md5-private.h"
+#include "md5.h"
+#include "randgen.h"
+#include "str.h"
+#include "str-sanitize.h"
+#include "mech.h"
+#include "passdb.h"
+
+
+#define MAX_REALM_LEN 64
+
+/* Linear whitespace */
+#define IS_LWS(c) ((c) == ' ' || (c) == '\t')
+
+static const char *qop_names[] = { "auth", "auth-int", "auth-conf" };
+
+static string_t *get_digest_challenge(struct digest_auth_request *request)
+{
+	const struct auth_settings *set = request->auth_request.set;
+	buffer_t buf;
+	string_t *str;
+	const char *const *tmp;
+	unsigned char nonce[16];
+	unsigned char nonce_base64[MAX_BASE64_ENCODED_SIZE(sizeof(nonce))+1];
+	int i;
+	bool first_qop;
+
+	/*
+	   realm="hostname" (multiple allowed)
+	   nonce="randomized data, at least 64bit"
+	   qop="auth,auth-int,auth-conf"
+	   maxbuf=number (with auth-int, auth-conf, defaults to 64k)
+	   charset="utf-8" (iso-8859-1 if it doesn't exist)
+	   algorithm="md5-sess"
+	   cipher="3des,des,rc4-40,rc4,rc4-56" (with auth-conf)
+	*/
+
+	/* get 128bit of random data as nonce */
+	random_fill(nonce, sizeof(nonce));
+
+	buffer_create_from_data(&buf, nonce_base64, sizeof(nonce_base64));
+	base64_encode(nonce, sizeof(nonce), &buf);
+	buffer_append_c(&buf, '\0');
+	request->nonce = p_strdup(request->pool, buf.data);
+
+	str = t_str_new(256);
+	if (*set->realms_arr == NULL) {
+		/* If no realms are given, at least Cyrus SASL client defaults
+		   to destination host name */
+		str_append(str, "realm=\"\",");
+	} else {
+		for (tmp = set->realms_arr; *tmp != NULL; tmp++)
+			str_printfa(str, "realm=\"%s\",", *tmp);
+	}
+
+	str_printfa(str, "nonce=\"%s\",", request->nonce);
+
+	str_append(str, "qop=\""); first_qop = TRUE;
+	for (i = 0; i < QOP_COUNT; i++) {
+		if ((request->qop & (1 << i)) != 0) {
+			if (first_qop)
+				first_qop = FALSE;
+			else
+				str_append_c(str, ',');
+			str_append(str, qop_names[i]);
+		}
+	}
+	str_append(str, "\",");
+
+	str_append(str, "charset=\"utf-8\","
+		   "algorithm=\"md5-sess\"");
+	return str;
+}
+
+static bool verify_credentials(struct digest_auth_request *request,
+			       const unsigned char *credentials, size_t size)
+{
+	struct md5_context ctx;
+	unsigned char digest[MD5_RESULTLEN];
+	const char *a1_hex, *a2_hex, *response_hex;
+	int i;
+
+	/* get the MD5 password */
+	if (size != MD5_RESULTLEN) {
+                e_error(request->auth_request.mech_event,
+			"invalid credentials length");
+		return FALSE;
+	}
+
+	/*
+	   response =
+	     HEX( KD ( HEX(H(A1)),
+		     { nonce-value, ":" nc-value, ":",
+		       cnonce-value, ":", qop-value, ":", HEX(H(A2)) }))
+
+	   and if authzid is not empty:
+
+	   A1 = { H( { username-value, ":", realm-value, ":", passwd } ),
+		":", nonce-value, ":", cnonce-value, ":", authzid }
+
+	   else:
+
+	   A1 = { H( { username-value, ":", realm-value, ":", passwd } ),
+		":", nonce-value, ":", cnonce-value }
+
+	   If the "qop" directive's value is "auth", then A2 is:
+	
+	      A2       = { "AUTHENTICATE:", digest-uri-value }
+	
+	   If the "qop" value is "auth-int" or "auth-conf" then A2 is:
+	
+	      A2       = { "AUTHENTICATE:", digest-uri-value,
+		       ":00000000000000000000000000000000" }
+	*/
+
+	/* A1 */
+	md5_init(&ctx);
+	md5_update(&ctx, credentials, size);
+	md5_update(&ctx, ":", 1);
+	md5_update(&ctx, request->nonce, strlen(request->nonce));
+	md5_update(&ctx, ":", 1);
+	md5_update(&ctx, request->cnonce, strlen(request->cnonce));
+	if (request->authzid != NULL) {
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, request->authzid, strlen(request->authzid));
+	}
+	md5_final(&ctx, digest);
+	a1_hex = binary_to_hex(digest, 16);
+
+	/* do it twice, first verify the user's response, the second is
+	   sent for client as a reply */
+	for (i = 0; i < 2; i++) {
+		/* A2 */
+		md5_init(&ctx);
+		if (i == 0)
+			md5_update(&ctx, "AUTHENTICATE:", 13);
+		else
+			md5_update(&ctx, ":", 1);
+
+		if (request->digest_uri != NULL) {
+			md5_update(&ctx, request->digest_uri,
+				   strlen(request->digest_uri));
+		}
+		if (request->qop == QOP_AUTH_INT ||
+		    request->qop == QOP_AUTH_CONF) {
+			md5_update(&ctx, ":00000000000000000000000000000000",
+				   33);
+		}
+		md5_final(&ctx, digest);
+		a2_hex = binary_to_hex(digest, 16);
+
+		/* response */
+		md5_init(&ctx);
+		md5_update(&ctx, a1_hex, 32);
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, request->nonce, strlen(request->nonce));
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, request->nonce_count,
+			   strlen(request->nonce_count));
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, request->cnonce, strlen(request->cnonce));
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, request->qop_value,
+			   strlen(request->qop_value));
+		md5_update(&ctx, ":", 1);
+		md5_update(&ctx, a2_hex, 32);
+		md5_final(&ctx, digest);
+		response_hex = binary_to_hex(digest, 16);
+
+		if (i == 0) {
+			/* verify response */
+			if (!mem_equals_timing_safe(response_hex, request->response, 32)) {
+				auth_request_log_info(&request->auth_request,
+						      AUTH_SUBSYS_MECH,
+						      AUTH_LOG_MSG_PASSWORD_MISMATCH);
+				return FALSE;
+			}
+		} else {
+			request->rspauth =
+				p_strconcat(request->pool, "rspauth=",
+					    response_hex, NULL);
+		}
+	}
+
+	return TRUE;
+}
+
+static bool parse_next(char **data, char **key, char **value)
+{
+	/* @UNSAFE */
+	char *p, *dest;
+
+	p = *data;
+	while (IS_LWS(*p)) p++;
+
+	/* get key */
+	*key = p;
+	while (*p != '\0' && *p != '=' && *p != ',')
+		p++;
+
+	if (*p != '=') {
+		*data = p;
+		return FALSE;
+	}
+
+	*value = p+1;
+
+	/* skip trailing whitespace in key */
+	while (p > *data && IS_LWS(p[-1]))
+		p--;
+	*p = '\0';
+
+	/* get value */
+	p = *value;
+	while (IS_LWS(*p)) p++;
+
+	if (*p != '"') {
+		while (*p != '\0' && *p != ',')
+			p++;
+
+		*data = p;
+		/* If there is more to parse, ensure it won't get skipped
+		   because *p is set to NUL below */
+		if (**data != '\0') (*data)++;
+		while (IS_LWS(p[-1]))
+			p--;
+		*p = '\0';
+	} else {
+		/* quoted string */
+		*value = dest = ++p;
+		while (*p != '\0' && *p != '"') {
+			if (*p == '\\' && p[1] != '\0')
+				p++;
+			*dest++ = *p++;
+		}
+
+		*data = *p == '"' ? p+1 : p;
+		*dest = '\0';
+	}
+
+	return TRUE;
+}
+
+static bool auth_handle_response(struct digest_auth_request *request,
+				 char *key, char *value, const char **error)
+{
+	unsigned int i;
+
+	(void)str_lcase(key);
+
+	if (strcmp(key, "realm") == 0) {
+		if (request->auth_request.fields.realm == NULL && *value != '\0')
+			auth_request_set_realm(&request->auth_request, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "username") == 0) {
+		if (request->username != NULL) {
+			*error = "username must not exist more than once";
+			return FALSE;
+		}
+
+		if (*value == '\0') {
+			*error = "empty username";
+			return FALSE;
+		}
+
+		request->username = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "nonce") == 0) {
+		/* nonce must be same */
+		if (strcmp(value, request->nonce) != 0) {
+			*error = "Invalid nonce";
+			return FALSE;
+		}
+
+		request->nonce_found = TRUE;
+		return TRUE;
+	}
+
+	if (strcmp(key, "cnonce") == 0) {
+		if (request->cnonce != NULL) {
+			*error = "cnonce must not exist more than once";
+			return FALSE;
+		}
+
+		if (*value == '\0') {
+			*error = "cnonce can't contain empty value";
+			return FALSE;
+		}
+
+		request->cnonce = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "nc") == 0) {
+		unsigned int nc;
+
+		if (request->nonce_count != NULL) {
+			*error = "nonce-count must not exist more than once";
+			return FALSE;
+		}
+
+		if (str_to_uint(value, &nc) < 0) {
+			*error = "nonce-count value invalid";
+			return FALSE;
+		}
+
+		if (nc != 1) {
+			*error = "re-auth not supported currently";
+			return FALSE;
+		}
+
+		request->nonce_count = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "qop") == 0) {
+		for (i = 0; i < QOP_COUNT; i++) {
+			if (strcasecmp(qop_names[i], value) == 0)
+				break;
+		}
+
+		if (i == QOP_COUNT) {
+			*error = t_strdup_printf("Unknown QoP value: %s",
+					str_sanitize(value, 32));
+			return FALSE;
+		}
+
+		request->qop &= (1 << i);
+		if (request->qop == 0) {
+			*error = "Nonallowed QoP requested";
+			return FALSE;
+		} 
+
+		request->qop_value = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "digest-uri") == 0) {
+		/* type / host / serv-name */
+		const char *const *uri = t_strsplit(value, "/");
+
+		if (uri[0] == NULL || uri[1] == NULL) {
+			*error = "Invalid digest-uri";
+			return FALSE;
+		}
+
+		/* FIXME: RFC recommends that we verify the host/serv-type.
+		   But isn't the realm enough already? That'd be just extra
+		   configuration.. Maybe optionally list valid hosts in
+		   config file? */
+		request->digest_uri = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	if (strcmp(key, "maxbuf") == 0) {
+		if (request->maxbuf != 0) {
+			*error = "maxbuf must not exist more than once";
+			return FALSE;
+		}
+
+		if (str_to_ulong(value, &request->maxbuf) < 0 ||
+		    request->maxbuf == 0) {
+			*error = "Invalid maxbuf value";
+			return FALSE;
+		}
+		return TRUE;
+	}
+
+	if (strcmp(key, "charset") == 0) {
+		if (strcasecmp(value, "utf-8") != 0) {
+			*error = "Only utf-8 charset is allowed";
+			return FALSE;
+		}
+
+		return TRUE;
+	}
+
+	if (strcmp(key, "response") == 0) {
+		if (strlen(value) != 32) {
+			*error = "Invalid response value";
+			return FALSE;
+		}
+
+		memcpy(request->response, value, 32);
+		return TRUE;
+	}
+
+	if (strcmp(key, "cipher") == 0) {
+		/* not supported, ignore */
+		return TRUE;
+	}
+
+	if (strcmp(key, "authzid") == 0) {
+		if (request->authzid != NULL) {
+		    *error = "authzid must not exist more than once";
+		    return FALSE;
+		}
+
+		if (*value == '\0') {
+		    *error = "empty authzid";
+		    return FALSE;
+		}
+
+		request->authzid = p_strdup(request->pool, value);
+		return TRUE;
+	}
+
+	/* unknown key, ignore */
+	return TRUE;
+}
+
+static bool parse_digest_response(struct digest_auth_request *request,
+				  const unsigned char *data, size_t size,
+				  const char **error)
+{
+	char *copy, *key, *value;
+	bool failed;
+
+	/*
+	   realm="realm"
+	   username="username"
+	   nonce="randomized data"
+	   cnonce="??"
+	   nc=00000001
+	   qop="auth|auth-int|auth-conf"
+	   digest-uri="serv-type/host[/serv-name]"
+	   response=32 HEX digits
+	   maxbuf=number (with auth-int, auth-conf, defaults to 64k)
+	   charset="utf-8" (iso-8859-1 if it doesn't exist)
+	   cipher="cipher-value"
+	   authzid="authzid-value"
+	*/
+
+	*error = NULL;
+	failed = FALSE;
+
+	if (size == 0) {
+		*error = "Client sent no input";
+		return FALSE;
+	}
+
+	/* treating response as NUL-terminated string also gets rid of all
+	   potential problems with NUL characters in strings. */
+	copy = t_strdup_noconst(t_strndup(data, size));
+	while (*copy != '\0') {
+		if (parse_next(&copy, &key, &value)) {
+			if (!auth_handle_response(request, key, value, error)) {
+				failed = TRUE;
+				break;
+			}
+		}
+
+		if (*copy == ',')
+			copy++;
+	}
+
+	if (!failed) {
+		if (!request->nonce_found) {
+			*error = "Missing nonce parameter";
+			failed = TRUE;
+		} else if (request->cnonce == NULL) {
+			*error = "Missing cnonce parameter";
+			failed = TRUE;
+		} else if (request->username == NULL) {
+			*error = "Missing username parameter";
+			failed = TRUE;
+		}
+	}
+
+	if (request->nonce_count == NULL)
+		request->nonce_count = p_strdup(request->pool, "00000001");
+	if (request->qop_value == NULL)
+		request->qop_value = p_strdup(request->pool, "auth");
+
+	return !failed;
+}
+
+static void credentials_callback(enum passdb_result result,
+				 const unsigned char *credentials, size_t size,
+				 struct auth_request *auth_request)
+{
+	struct digest_auth_request *request =
+		(struct digest_auth_request *)auth_request;
+
+	switch (result) {
+	case PASSDB_RESULT_OK:
+		if (!verify_credentials(request, credentials, size)) {
+			auth_request_fail(auth_request);
+			return;
+		}
+
+		auth_request_success(auth_request, request->rspauth,
+				     strlen(request->rspauth));
+		break;
+	case PASSDB_RESULT_INTERNAL_FAILURE:
+		auth_request_internal_failure(auth_request);
+		break;
+	default:
+		auth_request_fail(auth_request);
+		break;
+	}
+}
+
+static void
+mech_digest_md5_auth_continue(struct auth_request *auth_request,
+			      const unsigned char *data, size_t data_size)
+{
+	struct digest_auth_request *request =
+		(struct digest_auth_request *)auth_request;
+	const char *username, *error;
+
+	if (parse_digest_response(request, data, data_size, &error)) {
+		if (auth_request->fields.realm != NULL &&
+		    strchr(request->username, '@') == NULL) {
+			username = t_strconcat(request->username, "@",
+					       auth_request->fields.realm, NULL);
+			auth_request->domain_is_realm = TRUE;
+		} else {
+			username = request->username;
+		}
+
+		if (auth_request_set_username(auth_request, username, &error) &&
+				(request->authzid == NULL ||
+				 auth_request_set_login_username(auth_request,
+								 request->authzid,
+								 &error))) {
+			auth_request_lookup_credentials(auth_request,
+					"DIGEST-MD5", credentials_callback);
+			return;
+		}
+	}
+
+	if (error != NULL)
+                e_info(auth_request->mech_event, "%s", error);
+
+	auth_request_fail(auth_request);
+}
+
+static void
+mech_digest_md5_auth_initial(struct auth_request *auth_request,
+			     const unsigned char *data ATTR_UNUSED,
+			     size_t data_size ATTR_UNUSED)
+{
+	struct digest_auth_request *request =
+		(struct digest_auth_request *)auth_request;
+	string_t *challenge;
+
+	/* FIXME: there's no support for subsequent authentication */
+
+	challenge = get_digest_challenge(request);
+	auth_request_handler_reply_continue(auth_request, str_data(challenge),
+					    str_len(challenge));
+}
+
+static struct auth_request *mech_digest_md5_auth_new(void)
+{
+	struct digest_auth_request *request;
+	pool_t pool;
+
+	pool = pool_alloconly_create(MEMPOOL_GROWING"digest_md5_auth_request", 2048);
+	request = p_new(pool, struct digest_auth_request, 1);
+	request->pool = pool;
+	request->qop = QOP_AUTH;
+
+	request->auth_request.pool = pool;
+	return &request->auth_request;
+}
+
+const struct mech_module mech_digest_md5 = {
+	"DIGEST-MD5",
+
+	.flags = MECH_SEC_DICTIONARY | MECH_SEC_ACTIVE |
+		MECH_SEC_MUTUAL_AUTH,
+	.passdb_need = MECH_PASSDB_NEED_LOOKUP_CREDENTIALS,
+
+	mech_digest_md5_auth_new,
+	mech_digest_md5_auth_initial,
+	mech_digest_md5_auth_continue,
+	mech_generic_auth_free
+};