More complete patch, thanks for the feedback. Other options include -> kill mod_digest.c
and/or -> move mod_auth_digest.c from exp. into standard as this fix requires a MM bump _or_ so much rewriting that it may be easier to spend some cycles on mod_auth_digest.c. Dw Index: src/ApacheCore.def =================================================================== RCS file: /home/cvs/apache-1.3/src/ApacheCore.def,v retrieving revision 1.35 diff -u -r1.35 ApacheCore.def --- src/ApacheCore.def 18 Jun 2002 04:19:46 -0000 1.35 +++ src/ApacheCore.def 18 Dec 2003 21:25:49 -0000 @@ -447,3 +447,4 @@ ap_getline @439 ap_get_chunk_size @440 ap_escape_logitem @441 + ap_auth_nonce @442 Index: src/ApacheCoreOS2.def =================================================================== RCS file: /home/cvs/apache-1.3/src/ApacheCoreOS2.def,v retrieving revision 1.13 diff -u -r1.13 ApacheCoreOS2.def --- src/ApacheCoreOS2.def 22 May 2003 09:45:28 -0000 1.13 +++ src/ApacheCoreOS2.def 18 Dec 2003 21:25:50 -0000 @@ -430,3 +430,4 @@ ap_escape_logitem @441 ap_popenf_ex @442 ap_psocket_ex @443 + ap_auth_nonce @444 Index: src/CHANGES =================================================================== RCS file: /home/cvs/apache-1.3/src/CHANGES,v retrieving revision 1.1914 diff -u -r1.1914 CHANGES --- src/CHANGES 14 Dec 2003 18:16:49 -0000 1.1914 +++ src/CHANGES 18 Dec 2003 21:25:56 -0000 @@ -1,5 +1,11 @@ Changes with Apache 1.3.30 + *) SECURITY - verification as to wether the nonce returned in the + client response is one we issued ourselves by means of a + AuthNonce secret exposed as an md5(). See mod_digest documentation + for more details. The experimental/mod_auth_digest.c does not + have this issue. [Dirk-Willem van Gulik] + *) SECURITY [CAN-2003-0020]: Escape arbitrary data before writing into the errorlog. [André Malo] Index: src/include/ap_mmn.h =================================================================== RCS file: /home/cvs/apache-1.3/src/include/ap_mmn.h,v retrieving revision 1.65 diff -u -r1.65 ap_mmn.h --- src/include/ap_mmn.h 14 Dec 2003 18:16:49 -0000 1.65 +++ src/include/ap_mmn.h 18 Dec 2003 21:25:56 -0000 @@ -244,6 +244,8 @@ * ap_popenf_ex() and ap_psocket_ex(). * 19990320.15 - ap_is_recursion_limit_exceeded() * 19990320.16 - ap_escape_errorlog_item() + * 20031212 1.3.30-dev - ap_auth_nonce() and auth_nonce added + * in the request_rec. */ #define MODULE_MAGIC_COOKIE 0x41503133UL /* "AP13" */ Index: src/include/http_core.h =================================================================== RCS file: /home/cvs/apache-1.3/src/include/http_core.h,v retrieving revision 1.71 diff -u -r1.71 http_core.h --- src/include/http_core.h 7 Jul 2003 00:34:09 -0000 1.71 +++ src/include/http_core.h 18 Dec 2003 21:25:56 -0000 @@ -162,6 +162,7 @@ API_EXPORT(const char *) ap_auth_type (request_rec *); API_EXPORT(const char *) ap_auth_name (request_rec *); +API_EXPORT(const char *) ap_auth_nonce (request_rec *); API_EXPORT(int) ap_satisfies (request_rec *r); API_EXPORT(const array_header *) ap_requires (request_rec *); @@ -244,6 +245,7 @@ int satisfy; char *ap_auth_type; char *ap_auth_name; + char *ap_auth_nonce; /* digest auth */ array_header *ap_requires; /* Custom response config. These can contain text or a URL to redirect to. Index: src/main/http_core.c =================================================================== RCS file: /home/cvs/apache-1.3/src/main/http_core.c,v retrieving revision 1.327 diff -u -r1.327 http_core.c --- src/main/http_core.c 17 Nov 2003 17:14:53 -0000 1.327 +++ src/main/http_core.c 18 Dec 2003 21:25:58 -0000 @@ -236,6 +236,9 @@ if (new->ap_auth_name) { conf->ap_auth_name = new->ap_auth_name; } + if (new->ap_auth_nonce) { + conf->ap_auth_nonce= new->ap_auth_nonce; + } if (new->ap_requires) { conf->ap_requires = new->ap_requires; } @@ -577,6 +580,29 @@ return conf->ap_auth_name; } +API_EXPORT(const char *) ap_auth_nonce(request_rec *r) +{ + core_dir_config *conf; + conf = (core_dir_config *)ap_get_module_config(r->per_dir_config, + &core_module); + if (conf->ap_auth_nonce) + return conf->ap_auth_nonce; + + /* Ideally we'd want to mix in some per-directory style + * information; as we are likely to want to detect replay + * across those boundaries and some randomness. But that + * is harder due to the adhoc nature of .htaccess memory + * structures, restarts and forks. + * + * But then again - you should use AuthNonce in your config + * file if you care. So the adhoc value should do. + */ + return ap_psprintf(r->pool,"%lu%lu%lu%lu%lu%s", + *(unsigned long *)&((r->connection->local_addr).sin_addr ), + ap_user_name, ap_listeners, ap_server_argv0, ap_pid_fname + ); +} + API_EXPORT(const char *) ap_default_type(request_rec *r) { core_dir_config *conf; @@ -2797,6 +2823,28 @@ return NULL; } +/* + * Load an authorisation nonce into our location configuration, and + * force it to be in the 0-9/A-Z realm. + */ +static const char *set_authnonce (cmd_parms *cmd, void *mconfig, char *word1) +{ + core_dir_config *aconfig = (core_dir_config *)mconfig; + int i; + + aconfig->ap_auth_nonce = ap_escape_quotes(cmd->pool, word1); + + if (strlen(aconfig->ap_auth_nonce) > 510) + return "AuthNonce length limited to 510 chars for browser compatibility"; + + for(i=0;i<strlen(aconfig->ap_auth_nonce );i++) + if (!ap_isalnum(aconfig->ap_auth_nonce [i])) + return "AuthNonce limited to 0-9 and A-Z range for browser compatibility"; + + return NULL; +} + + #ifdef _OSD_POSIX /* BS2000 Logon Passwd file */ static const char *set_bs2000_account(cmd_parms *cmd, void *dummy, char *name) { @@ -3411,6 +3459,9 @@ "An HTTP authorization type (e.g., \"Basic\")" }, { "AuthName", set_authname, NULL, OR_AUTHCFG, TAKE1, "The authentication realm (e.g. \"Members Only\")" }, +{ "AuthNonce", set_authnonce, NULL, OR_AUTHCFG, TAKE1, + "An authentication token which should be different for each logical realm. "\ + "A random value or the servers IP may be a good choise.\n" }, { "Require", require, NULL, OR_AUTHCFG, RAW_ARGS, "Selects which authenticated users or groups may access a protected space" }, { "Satisfy", satisfy, NULL, OR_AUTHCFG, TAKE1, Index: src/main/http_protocol.c =================================================================== RCS file: /home/cvs/apache-1.3/src/main/http_protocol.c,v retrieving revision 1.330 diff -u -r1.330 http_protocol.c --- src/main/http_protocol.c 3 Feb 2003 17:13:22 -0000 1.330 +++ src/main/http_protocol.c 18 Dec 2003 21:26:00 -0000 @@ -76,6 +76,7 @@ #include "util_date.h" /* For parseHTTPdate and BAD_DATE */ #include <stdarg.h> #include "http_conf_globals.h" +#include "util_md5.h" /* For digestAuth */ #define SET_BYTES_SENT(r) \ do { if (r->sent_bodyct) \ @@ -1391,11 +1392,24 @@ API_EXPORT(void) ap_note_digest_auth_failure(request_rec *r) { + /* We need to create a nonce which: + * a) changes all the time (see r->request_time) + * below and + * b) of which we can verify that it is our own + * fairly easily when it comes to veryfing + * the digest coming back in the response. + * c) and which as a whole should not + * be unlikely to be in use anywhere else. + */ + char * nonce_prefix = ap_md5(r->pool, + ap_psprintf(r->pool, "%s%lu", + ap_auth_nonce(r), r->request_time)); + ap_table_setn(r->err_headers_out, r->proxyreq == STD_PROXY ? "Proxy-Authenticate" : "WWW-Authenticate", - ap_psprintf(r->pool, "Digest realm=\"%s\", nonce=\"%lu\"", - ap_auth_name(r), r->request_time)); + ap_psprintf(r->pool, "Digest realm=\"%s\", nonce=\"%s%lu\"", + ap_auth_name(r), nonce_prefix, r->request_time)); } API_EXPORT(int) ap_get_basic_auth_pw(request_rec *r, const char **pw) Index: src/modules/standard/mod_digest.c =================================================================== RCS file: /home/cvs/apache-1.3/src/modules/standard/mod_digest.c,v retrieving revision 1.52 diff -u -r1.52 mod_digest.c --- src/modules/standard/mod_digest.c 3 Feb 2003 17:13:27 -0000 1.52 +++ src/modules/standard/mod_digest.c 18 Dec 2003 21:26:00 -0000 @@ -316,6 +316,23 @@ /* The actual MD5 code... whee */ +/* Check that a given nonce is actually one which was + * issued by this server in the right context. + */ +static int check_nonce(pool *p, char * prefix, const char * nonce) { + char * timestamp = (char *)nonce + 2 * MD5_DIGESTSIZE; + char * md5; + + if (strlen(nonce) < MD5_DIGESTSIZE) + return AUTH_REQUIRED; + + md5 = ap_md5(p, ap_pstrcat(p, prefix, timestamp, NULL)); + + return strncmp(md5, nonce, 2 * MD5_DIGESTSIZE); +} + +/* Check the digest itself. + */ static char *find_digest(request_rec *r, digest_header_rec * h, char *a1) { return ap_md5(r->pool, @@ -339,7 +356,6 @@ /* Determine user ID, and check if it really is that user, for HTTP * basic authentication... */ - static int authenticate_digest_user(request_rec *r) { digest_config_rec *sec = @@ -355,7 +371,16 @@ if (!sec->pwfile) return DECLINED; - + + /* Check that the nonce was one we actually issued. */ + if (check_nonce(r->pool, ap_auth_nonce(r), response->nonce)) { + ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r, + "Client is using a nonce which was not issued by " + "this server for this context: %s", r->uri); + ap_note_digest_auth_failure(r); + return AUTH_REQUIRED; + } + if (!(a1 = get_hash(r, c->user, sec->pwfile))) { ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r, "user %s not found: %s", c->user, r->uri); Index: htdocs/manual/mod/mod_digest.html =================================================================== RCS file: /home/cvs/httpd-docs-1.3/htdocs/manual/mod/mod_digest.html,v retrieving revision 1.14 diff -u -r1.14 mod_digest.html --- htdocs/manual/mod/mod_digest.html 23 Jan 2002 02:51:03 -0000 1.14 +++ htdocs/manual/mod/mod_digest.html 18 Dec 2003 21:26:51 -0000 @@ -48,17 +48,28 @@ <p>Using MD5 Digest authentication is very simple. Simply set up authentication normally. However, use "AuthType Digest" and "AuthDigestFile" instead of the normal "AuthType Basic" and - "AuthUserFile". Everything else should remain the same.</p> + "AuthUserFile". + + <p>As to make sure that replay is not possible across + sections of the site, or across sites (assuming a realm, + userid and password are valid in that wider context) a + secret nonce prefix can be configured with the + core directive <a href="core.html#AuthNonce">AuthNonce</a>. + </p> + <p>If none if configured a sensible, but not particular + secure, default is used. When used in load balancing + situations the prefix should be shared across servers. + </p> + <p>The experimental <a href="mod_auth_digest.html">mod_auth_digest</a> + module offers a number of additinal protections against replay. + </p> + + <p>Everything else should remain the same.</p> <p>MD5 authentication provides a more secure password system, but only works with supporting browsers. As of this writing - (January 2002), the only major browsers which support digest - authentication are <a href="http://www.opera.com/">Opera 4.0</a>, - <a href="http://www.microsoft.com/windows/ie/">MS Internet - Explorer 5.0</a> and <a href="http://www.w3.org/Amaya/">Amaya</a>. - Therefore, we do not recommend using this feature on a large - Internet site. However, for personal and intra-net use, where - browser users can be controlled, it is ideal.</p> + (December 2003), most major browsers support digest authentication. + </p> <p>See also <a href="mod_auth_digest.html">mod_auth_digest</a>, which is an updated version of this module, in order to determine Index: htdocs/manual/mod/core.html.en =================================================================== RCS file: /home/cvs/httpd-docs-1.3/htdocs/manual/mod/core.html.en,v retrieving revision 1.257 diff -u -r1.257 core.html.en --- htdocs/manual/mod/core.html.en 3 Dec 2003 10:35:24 -0000 1.257 +++ htdocs/manual/mod/core.html.en 18 Dec 2003 21:36:14 -0000 @@ -37,6 +37,8 @@ <li><a href="#authname">AuthName</a></li> + <li><a href="#AuthNonce">AuthNonce</a></li> + <li><a href="#authtype">AuthType</a></li> <li><a href="#bindaddress">BindAddress</a></li> @@ -498,6 +500,7 @@ href="mod_auth_dbm.html#authdbmuserfile">AuthDBMUserFile</a>, <a href="mod_auth.html#authgroupfile">AuthGroupFile</a>, <a href="#authname">AuthName</a>, <a + href="#AuthNonce">AuthNonce</a>, <a href="#authtype">AuthType</a>, <a href="mod_auth.html#authuserfile">AuthUserFile</a>, <a href="#require">Require</a>, <em>etc.</em>).</dd> @@ -593,6 +596,42 @@ Access Control</a></p> <hr /> + <h2><a id="AuthNonce" name="AuthNonce">AuthNonce + directive</a></h2> + + <a href="directive-dict.html#Syntax" + rel="Help"><strong>Syntax:</strong></a> AuthNonce + <em>secret-real-string</em><br /> + <a href="directive-dict.html#Context" + rel="Help"><strong>Context:</strong></a> directory, + .htaccess<br /> + <a href="directive-dict.html#Override" + rel="Help"><strong>Override:</strong></a> AuthConfig<br /> + <a href="directive-dict.html#Status" + rel="Help"><strong>Status:</strong></a> core + + <p>This directive sets a per realm secret nonce prefix + which is used to ensure that a captured username, password + and realm string during a Digest exchange cannot + be replayed at other places. + </p> + <p>It only applies to <a href="mod_digest.html">mod_digest.html</a>, + the experimental <a href="mod_auth_digest.html">mod_auth_digest.html</a> + implements its own (more advanced and also time sensitive) replay protection. + </p> + + It must be accompanied by <a href="#authtype">AuthType</a> of + type Digest, one or more + <a href="#require">Require</a> directives, and directives such + as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a + href="mod_auth.html#authgroupfile">AuthGroupFile</a> to + work.</p> + + <p><strong>See also:</strong> <a + href="../howto/auth.html">Authentication, Authorization, and + Access Control</a></p> + <hr /> + <h2><a id="authtype" name="authtype">AuthType directive</a></h2> @@ -616,6 +655,9 @@ as <a href="mod_auth.html#authuserfile">AuthUserFile</a> and <a href="mod_auth.html#authgroupfile">AuthGroupFile</a> to work.</p> + + <p>When AuthDigest is used an <a href="#AuthNonce">AuthNonce</a> + should also be set.</p> <p><strong>See also:</strong> <a href="../howto/auth.html">Authentication, Authorization, and