2 * sasl_auth.c : Functions for SASL-based authentication
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5 * Licensed to the Apache Software Foundation (ASF) under one
6 * or more contributor license agreements. See the NOTICE file
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8 * regarding copyright ownership. The ASF licenses this file
9 * to you under the Apache License, Version 2.0 (the
10 * "License"); you may not use this file except in compliance
11 * with the License. You may obtain a copy of the License at
13 * http://www.apache.org/licenses/LICENSE-2.0
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19 * specific language governing permissions and limitations
21 * ====================================================================
24 #include "svn_private_config.h"
27 #define APR_WANT_STRFUNC
29 #include <apr_general.h>
30 #include <apr_strings.h>
32 #include "svn_types.h"
33 #include "svn_string.h"
34 #include "svn_pools.h"
35 #include "svn_error.h"
36 #include "svn_ra_svn.h"
37 #include "svn_base64.h"
39 #include "private/svn_atomic.h"
40 #include "private/ra_svn_sasl.h"
41 #include "private/svn_ra_svn_private.h"
45 /* SASL calls this function before doing anything with a username, which gives
46 us an opportunity to do some sanity-checking. If the username contains
47 an '@', SASL interprets the part following the '@' as the name of the
48 authentication realm, and worst of all, this realm overrides the one that
49 we pass to sasl_server_new(). If we didn't check this, a user that could
50 successfully authenticate in one realm would be able to authenticate
51 in any other realm, simply by appending '@realm' to his username.
53 Note that the value returned in *OUT does not need to be
54 '\0'-terminated; we just need to set *OUT_LEN correctly.
56 static int canonicalize_username(sasl_conn_t *conn,
57 void *context, /* not used */
58 const char *in, /* the username */
59 unsigned inlen, /* its length */
60 unsigned flags, /* not used */
61 const char *user_realm,
62 char *out, /* the output buffer */
63 unsigned out_max, unsigned *out_len)
65 size_t realm_len = strlen(user_realm);
70 /* If the username contains an '@', the part after the '@' is the realm
71 that the user wants to authenticate in. */
72 pos = memchr(in, '@', inlen);
75 /* The only valid realm is user_realm (i.e. the repository's realm).
76 If the user gave us another realm, complain. */
77 if (realm_len != inlen-(pos-in+1))
79 if (strncmp(pos+1, user_realm, inlen-(pos-in+1)) != 0)
83 *out_len += realm_len + 1;
85 /* First, check that the output buffer is large enough. */
86 if (*out_len > out_max)
89 /* Copy the username part. */
90 strncpy(out, in, inlen);
92 /* If necessary, copy the realm part. */
96 strncpy(&out[inlen+1], user_realm, realm_len);
102 static sasl_callback_t callbacks[] =
104 { SASL_CB_CANON_USER, (int (*)(void))canonicalize_username, NULL },
105 { SASL_CB_LIST_END, NULL, NULL }
108 static svn_error_t *initialize(void *baton, apr_pool_t *pool)
111 SVN_ERR(svn_ra_svn__sasl_common_init(pool));
113 /* The second parameter tells SASL to look for a configuration file
114 named subversion.conf. */
115 result = sasl_server_init(callbacks, SVN_RA_SVN_SASL_NAME);
116 if (result != SASL_OK)
118 svn_error_t *err = svn_error_create(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
119 sasl_errstring(result, NULL, NULL));
120 return svn_error_quick_wrap(err,
121 _("Could not initialize the SASL library"));
126 svn_error_t *cyrus_init(apr_pool_t *pool)
128 SVN_ERR(svn_atomic__init_once(&svn_ra_svn__sasl_status,
129 initialize, NULL, pool));
133 /* Tell the client the authentication failed. This is only used during
134 the authentication exchange (i.e. inside try_auth()). */
136 fail_auth(svn_ra_svn_conn_t *conn, apr_pool_t *pool, sasl_conn_t *sasl_ctx)
138 const char *msg = sasl_errdetail(sasl_ctx);
139 SVN_ERR(svn_ra_svn__write_tuple(conn, pool, "w(c)", "failure", msg));
140 return svn_ra_svn__flush(conn, pool);
143 /* Like svn_ra_svn_write_cmd_failure, but also clears the given error
144 and sets it to SVN_NO_ERROR. */
146 write_failure(svn_ra_svn_conn_t *conn, apr_pool_t *pool, svn_error_t **err_p)
148 svn_error_t *write_err = svn_ra_svn__write_cmd_failure(conn, pool, *err_p);
149 svn_error_clear(*err_p);
150 *err_p = SVN_NO_ERROR;
154 /* Used if we run into a SASL error outside try_auth(). */
156 fail_cmd(svn_ra_svn_conn_t *conn, apr_pool_t *pool, sasl_conn_t *sasl_ctx)
158 svn_error_t *err = svn_error_create(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
159 sasl_errdetail(sasl_ctx));
160 SVN_ERR(write_failure(conn, pool, &err));
161 return svn_ra_svn__flush(conn, pool);
164 static svn_error_t *try_auth(svn_ra_svn_conn_t *conn,
165 sasl_conn_t *sasl_ctx,
168 svn_boolean_t *success)
170 const char *out, *mech;
171 const svn_string_t *arg = NULL, *in;
174 svn_boolean_t use_base64;
178 /* Read the client's chosen mech and the initial token. */
179 SVN_ERR(svn_ra_svn__read_tuple(conn, pool, "w(?s)", &mech, &in));
181 if (strcmp(mech, "EXTERNAL") == 0 && !in)
182 in = svn_string_create(b->client_info->tunnel_user, pool);
184 in = svn_base64_decode_string(in, pool);
186 /* For CRAM-MD5, we don't base64-encode stuff. */
187 use_base64 = (strcmp(mech, "CRAM-MD5") != 0);
189 /* sasl uses unsigned int for the length of strings, we use apr_size_t
190 * which may not be the same size. Deal with potential integer overflow */
191 if (in && in->len > UINT_MAX)
192 return svn_error_createf(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
193 _("Initial token is too long"));
195 result = sasl_server_start(sasl_ctx, mech,
196 in ? in->data : NULL,
197 in ? (unsigned int) in->len : 0, &out, &outlen);
199 if (result != SASL_OK && result != SASL_CONTINUE)
200 return fail_auth(conn, pool, sasl_ctx);
202 while (result == SASL_CONTINUE)
204 svn_ra_svn_item_t *item;
206 arg = svn_string_ncreate(out, outlen, pool);
207 /* Encode what we send to the client. */
209 arg = svn_base64_encode_string2(arg, TRUE, pool);
211 SVN_ERR(svn_ra_svn__write_tuple(conn, pool, "w(s)", "step", arg));
213 /* Read and decode the client response. */
214 SVN_ERR(svn_ra_svn__read_item(conn, pool, &item));
215 if (item->kind != SVN_RA_SVN_STRING)
220 in = svn_base64_decode_string(in, pool);
222 if (in->len > UINT_MAX)
223 return svn_error_createf(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
224 _("Step response is too long"));
226 result = sasl_server_step(sasl_ctx, in->data, (unsigned int) in->len,
230 if (result != SASL_OK)
231 return fail_auth(conn, pool, sasl_ctx);
233 /* Send our last response, if necessary. */
235 arg = svn_base64_encode_string2(svn_string_ncreate(out, outlen, pool), TRUE,
241 SVN_ERR(svn_ra_svn__write_tuple(conn, pool, "w(?s)", "success", arg));
246 static apr_status_t sasl_dispose_cb(void *data)
248 sasl_conn_t *sasl_ctx = (sasl_conn_t*) data;
249 sasl_dispose(&sasl_ctx);
253 svn_error_t *cyrus_auth_request(svn_ra_svn_conn_t *conn,
256 enum access_type required,
257 svn_boolean_t needs_username)
259 sasl_conn_t *sasl_ctx;
261 apr_status_t apr_err;
262 const char *localaddrport = NULL, *remoteaddrport = NULL;
263 const char *mechlist;
264 char hostname[APRMAXHOSTLEN + 1];
265 sasl_security_properties_t secprops;
266 svn_boolean_t success, no_anonymous;
267 int mech_count, result = SASL_OK;
269 SVN_ERR(svn_ra_svn__get_addresses(&localaddrport, &remoteaddrport,
271 apr_err = apr_gethostname(hostname, sizeof(hostname), pool);
274 svn_error_t *err = svn_error_wrap_apr(apr_err, _("Can't get hostname"));
275 SVN_ERR(write_failure(conn, pool, &err));
276 return svn_ra_svn__flush(conn, pool);
279 /* Create a SASL context. SASL_SUCCESS_DATA tells SASL that the protocol
280 supports sending data along with the final "success" message. */
281 result = sasl_server_new(SVN_RA_SVN_SASL_NAME,
282 hostname, b->repository->realm,
283 localaddrport, remoteaddrport,
284 NULL, SASL_SUCCESS_DATA,
286 if (result != SASL_OK)
288 svn_error_t *err = svn_error_create(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
289 sasl_errstring(result, NULL, NULL));
290 SVN_ERR(write_failure(conn, pool, &err));
291 return svn_ra_svn__flush(conn, pool);
294 /* Make sure the context is always destroyed. */
295 apr_pool_cleanup_register(b->pool, sasl_ctx, sasl_dispose_cb,
296 apr_pool_cleanup_null);
298 /* Initialize security properties. */
299 svn_ra_svn__default_secprops(&secprops);
301 /* Don't allow ANONYMOUS if a username is required. */
302 no_anonymous = needs_username || b->repository->anon_access < required;
304 secprops.security_flags |= SASL_SEC_NOANONYMOUS;
306 secprops.min_ssf = b->repository->min_ssf;
307 secprops.max_ssf = b->repository->max_ssf;
309 /* Set security properties. */
310 result = sasl_setprop(sasl_ctx, SASL_SEC_PROPS, &secprops);
311 if (result != SASL_OK)
312 return fail_cmd(conn, pool, sasl_ctx);
314 /* SASL needs to know if we are externally authenticated. */
315 if (b->client_info->tunnel_user)
316 result = sasl_setprop(sasl_ctx, SASL_AUTH_EXTERNAL,
317 b->client_info->tunnel_user);
318 if (result != SASL_OK)
319 return fail_cmd(conn, pool, sasl_ctx);
321 /* Get the list of mechanisms. */
322 result = sasl_listmech(sasl_ctx, NULL, NULL, " ", NULL,
323 &mechlist, NULL, &mech_count);
325 if (result != SASL_OK)
326 return fail_cmd(conn, pool, sasl_ctx);
330 svn_error_t *err = svn_error_create(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
331 _("Could not obtain the list"
332 " of SASL mechanisms"));
333 SVN_ERR(write_failure(conn, pool, &err));
334 return svn_ra_svn__flush(conn, pool);
337 /* Send the list of mechanisms and the realm to the client. */
338 SVN_ERR(svn_ra_svn__write_cmd_response(conn, pool, "(w)c",
339 mechlist, b->repository->realm));
341 /* The main authentication loop. */
342 subpool = svn_pool_create(pool);
345 svn_pool_clear(subpool);
346 SVN_ERR(try_auth(conn, sasl_ctx, subpool, b, &success));
349 svn_pool_destroy(subpool);
351 SVN_ERR(svn_ra_svn__enable_sasl_encryption(conn, sasl_ctx, pool));
358 /* Get the authenticated username. */
359 result = sasl_getprop(sasl_ctx, SASL_USERNAME, &user);
361 if (result != SASL_OK)
362 return fail_cmd(conn, pool, sasl_ctx);
364 if ((p = strchr(user, '@')) != NULL)
366 /* Drop the realm part. */
367 b->client_info->user = apr_pstrndup(b->pool, user,
368 p - (const char *)user);
373 err = svn_error_create(SVN_ERR_RA_NOT_AUTHORIZED, NULL,
374 _("Couldn't obtain the authenticated"
376 SVN_ERR(write_failure(conn, pool, &err));
377 return svn_ra_svn__flush(conn, pool);
384 #endif /* SVN_HAVE_SASL */