diff options
Diffstat (limited to 'src/lib/libssl/doc/SSL_CTX_set_verify.3')
-rw-r--r-- | src/lib/libssl/doc/SSL_CTX_set_verify.3 | 415 |
1 files changed, 0 insertions, 415 deletions
diff --git a/src/lib/libssl/doc/SSL_CTX_set_verify.3 b/src/lib/libssl/doc/SSL_CTX_set_verify.3 deleted file mode 100644 index 9292f2086b..0000000000 --- a/src/lib/libssl/doc/SSL_CTX_set_verify.3 +++ /dev/null | |||
@@ -1,415 +0,0 @@ | |||
1 | .\" | ||
2 | .\" $OpenBSD: SSL_CTX_set_verify.3,v 1.2 2014/12/02 14:11:01 jmc Exp $ | ||
3 | .\" | ||
4 | .Dd $Mdocdate: December 2 2014 $ | ||
5 | .Dt SSL_CTX_SET_VERIFY 3 | ||
6 | .Os | ||
7 | .Sh NAME | ||
8 | .Nm SSL_CTX_set_verify , | ||
9 | .Nm SSL_set_verify , | ||
10 | .Nm SSL_CTX_set_verify_depth , | ||
11 | .Nm SSL_set_verify_depth | ||
12 | .Nd set peer certificate verification parameters | ||
13 | .Sh SYNOPSIS | ||
14 | .In openssl/ssl.h | ||
15 | .Ft void | ||
16 | .Fo SSL_CTX_set_verify | ||
17 | .Fa "SSL_CTX *ctx" | ||
18 | .Fa "int mode" | ||
19 | .Fa "int (*verify_callback)(int, X509_STORE_CTX *)" | ||
20 | .Fc | ||
21 | .Ft void | ||
22 | .Fo SSL_set_verify | ||
23 | .Fa "SSL *s" | ||
24 | .Fa "int mode" | ||
25 | .Fa "int (*verify_callback)(int, X509_STORE_CTX *)" | ||
26 | .Fc | ||
27 | .Ft void | ||
28 | .Fn SSL_CTX_set_verify_depth "SSL_CTX *ctx" "int depth" | ||
29 | .Ft void | ||
30 | .Fn SSL_set_verify_depth "SSL *s" "int depth" | ||
31 | .Ft int | ||
32 | .Fn verify_callback "int preverify_ok" "X509_STORE_CTX *x509_ctx" | ||
33 | .Sh DESCRIPTION | ||
34 | .Fn SSL_CTX_set_verify | ||
35 | sets the verification flags for | ||
36 | .Fa ctx | ||
37 | to be | ||
38 | .Fa mode | ||
39 | and | ||
40 | specifies the | ||
41 | .Fa verify_callback | ||
42 | function to be used. | ||
43 | If no callback function shall be specified, the | ||
44 | .Dv NULL | ||
45 | pointer can be used for | ||
46 | .Fa verify_callback . | ||
47 | .Pp | ||
48 | .Fn SSL_set_verify | ||
49 | sets the verification flags for | ||
50 | .Fa ssl | ||
51 | to be | ||
52 | .Fa mode | ||
53 | and specifies the | ||
54 | .Fa verify_callback | ||
55 | function to be used. | ||
56 | If no callback function shall be specified, the | ||
57 | .Dv NULL | ||
58 | pointer can be used for | ||
59 | .Fa verify_callback . | ||
60 | In this case last | ||
61 | .Fa verify_callback | ||
62 | set specifically for this | ||
63 | .Fa ssl | ||
64 | remains. | ||
65 | If no special callback was set before, the default callback for the underlying | ||
66 | .Fa ctx | ||
67 | is used, that was valid at the time | ||
68 | .Fa ssl | ||
69 | was created with | ||
70 | .Xr SSL_new 3 . | ||
71 | .Pp | ||
72 | .Fn SSL_CTX_set_verify_depth | ||
73 | sets the maximum | ||
74 | .Fa depth | ||
75 | for the certificate chain verification that shall be allowed for | ||
76 | .Fa ctx . | ||
77 | (See the | ||
78 | .Sx BUGS | ||
79 | section.) | ||
80 | .Pp | ||
81 | .Fn SSL_set_verify_depth | ||
82 | sets the maximum | ||
83 | .Fa depth | ||
84 | for the certificate chain verification that shall be allowed for | ||
85 | .Fa ssl . | ||
86 | (See the | ||
87 | .Sx BUGS | ||
88 | section.) | ||
89 | .Sh NOTES | ||
90 | The verification of certificates can be controlled by a set of bitwise ORed | ||
91 | .Fa mode | ||
92 | flags: | ||
93 | .Bl -tag -width Ds | ||
94 | .It Dv SSL_VERIFY_NONE | ||
95 | .Em Server mode: | ||
96 | the server will not send a client certificate request to the client, | ||
97 | so the client will not send a certificate. | ||
98 | .Pp | ||
99 | .Em Client mode: | ||
100 | if not using an anonymous cipher (by default disabled), | ||
101 | the server will send a certificate which will be checked. | ||
102 | The result of the certificate verification process can be checked after the | ||
103 | TLS/SSL handshake using the | ||
104 | .Xr SSL_get_verify_result 3 | ||
105 | function. | ||
106 | The handshake will be continued regardless of the verification result. | ||
107 | .It Dv SSL_VERIFY_PEER | ||
108 | .Em Server mode: | ||
109 | the server sends a client certificate request to the client. | ||
110 | The certificate returned (if any) is checked. | ||
111 | If the verification process fails, | ||
112 | the TLS/SSL handshake is immediately terminated with an alert message | ||
113 | containing the reason for the verification failure. | ||
114 | The behaviour can be controlled by the additional | ||
115 | .Dv SSL_VERIFY_FAIL_IF_NO_PEER_CERT | ||
116 | and | ||
117 | .Dv SSL_VERIFY_CLIENT_ONCE | ||
118 | flags. | ||
119 | .Pp | ||
120 | .Em Client mode: | ||
121 | the server certificate is verified. | ||
122 | If the verification process fails, | ||
123 | the TLS/SSL handshake is immediately terminated with an alert message | ||
124 | containing the reason for the verification failure. | ||
125 | If no server certificate is sent, because an anonymous cipher is used, | ||
126 | .Dv SSL_VERIFY_PEER | ||
127 | is ignored. | ||
128 | .It Dv SSL_VERIFY_FAIL_IF_NO_PEER_CERT | ||
129 | .Em Server mode: | ||
130 | if the client did not return a certificate, the TLS/SSL | ||
131 | handshake is immediately terminated with a | ||
132 | .Dq handshake failure | ||
133 | alert. | ||
134 | This flag must be used together with | ||
135 | .Dv SSL_VERIFY_PEER. | ||
136 | .Pp | ||
137 | .Em Client mode: | ||
138 | ignored | ||
139 | .It Dv SSL_VERIFY_CLIENT_ONCE | ||
140 | .Em Server mode: | ||
141 | only request a client certificate on the initial TLS/SSL handshake. | ||
142 | Do not ask for a client certificate again in case of a renegotiation. | ||
143 | This flag must be used together with | ||
144 | .Dv SSL_VERIFY_PEER . | ||
145 | .Pp | ||
146 | .Em Client mode: | ||
147 | ignored | ||
148 | .El | ||
149 | .Pp | ||
150 | Exactly one of the | ||
151 | .Fa mode | ||
152 | flags | ||
153 | .Dv SSL_VERIFY_NONE | ||
154 | and | ||
155 | .Dv SSL_VERIFY_PEER | ||
156 | must be set at any time. | ||
157 | .Pp | ||
158 | The actual verification procedure is performed either using the built-in | ||
159 | verification procedure or using another application provided verification | ||
160 | function set with | ||
161 | .Xr SSL_CTX_set_cert_verify_callback 3 . | ||
162 | The following descriptions apply in the case of the built-in procedure. | ||
163 | An application provided procedure also has access to the verify depth | ||
164 | information and the | ||
165 | .Fa verify_callback Ns () | ||
166 | function, but the way this information is used may be different. | ||
167 | .Pp | ||
168 | .Fn SSL_CTX_set_verify_depth | ||
169 | and | ||
170 | .Fn SSL_set_verify_depth | ||
171 | set the limit up to which depth certificates in a chain are used during the | ||
172 | verification procedure. | ||
173 | If the certificate chain is longer than allowed, | ||
174 | the certificates above the limit are ignored. | ||
175 | Error messages are generated as if these certificates would not be present, | ||
176 | most likely a | ||
177 | .Dv X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY | ||
178 | will be issued. | ||
179 | The depth count is | ||
180 | .Dq level 0: peer certificate , | ||
181 | .Dq level 1: CA certificate , | ||
182 | .Dq level 2: higher level CA certificate , | ||
183 | and so on. | ||
184 | Setting the maximum depth to 2 allows the levels 0, 1, and 2. | ||
185 | The default depth limit is 100, | ||
186 | allowing for the peer certificate and an additional 100 CA certificates. | ||
187 | .Pp | ||
188 | The | ||
189 | .Fa verify_callback | ||
190 | function is used to control the behaviour when the | ||
191 | .Dv SSL_VERIFY_PEER | ||
192 | flag is set. | ||
193 | It must be supplied by the application and receives two arguments: | ||
194 | .Fa preverify_ok | ||
195 | indicates whether the verification of the certificate in question was passed | ||
196 | (preverify_ok=1) or not (preverify_ok=0). | ||
197 | .Fa x509_ctx | ||
198 | is a pointer to the complete context used | ||
199 | for the certificate chain verification. | ||
200 | .Pp | ||
201 | The certificate chain is checked starting with the deepest nesting level | ||
202 | (the root CA certificate) and worked upward to the peer's certificate. | ||
203 | At each level signatures and issuer attributes are checked. | ||
204 | Whenever a verification error is found, the error number is stored in | ||
205 | .Fa x509_ctx | ||
206 | and | ||
207 | .Fa verify_callback | ||
208 | is called with | ||
209 | .Fa preverify_ok | ||
210 | equal to 0. | ||
211 | By applying | ||
212 | .Fn X509_CTX_store_* | ||
213 | functions | ||
214 | .Fa verify_callback | ||
215 | can locate the certificate in question and perform additional steps (see | ||
216 | .Sx EXAMPLES ) . | ||
217 | If no error is found for a certificate, | ||
218 | .Fa verify_callback | ||
219 | is called with | ||
220 | .Fa preverify_ok | ||
221 | equal to 1 before advancing to the next level. | ||
222 | .Pp | ||
223 | The return value of | ||
224 | .Fa verify_callback | ||
225 | controls the strategy of the further verification process. | ||
226 | If | ||
227 | .Fa verify_callback | ||
228 | returns 0, the verification process is immediately stopped with | ||
229 | .Dq verification failed | ||
230 | state. | ||
231 | If | ||
232 | .Dv SSL_VERIFY_PEER | ||
233 | is set, a verification failure alert is sent to the peer and the TLS/SSL | ||
234 | handshake is terminated. | ||
235 | If | ||
236 | .Fa verify_callback | ||
237 | returns 1, the verification process is continued. | ||
238 | If | ||
239 | .Fa verify_callback | ||
240 | always returns 1, | ||
241 | the TLS/SSL handshake will not be terminated with respect to verification | ||
242 | failures and the connection will be established. | ||
243 | The calling process can however retrieve the error code of the last | ||
244 | verification error using | ||
245 | .Xr SSL_get_verify_result 3 | ||
246 | or by maintaining its own error storage managed by | ||
247 | .Fa verify_callback . | ||
248 | .Pp | ||
249 | If no | ||
250 | .Fa verify_callback | ||
251 | is specified, the default callback will be used. | ||
252 | Its return value is identical to | ||
253 | .Fa preverify_ok , | ||
254 | so that any verification | ||
255 | failure will lead to a termination of the TLS/SSL handshake with an | ||
256 | alert message, if | ||
257 | .Dv SSL_VERIFY_PEER | ||
258 | is set. | ||
259 | .Sh RETURN VALUES | ||
260 | The | ||
261 | .Fn SSL*_set_verify* | ||
262 | functions do not provide diagnostic information. | ||
263 | .Sh EXAMPLES | ||
264 | The following code sequence realizes an example | ||
265 | .Fa verify_callback | ||
266 | function that will always continue the TLS/SSL handshake regardless of | ||
267 | verification failure, if wished. | ||
268 | The callback realizes a verification depth limit with more informational output. | ||
269 | .Pp | ||
270 | All verification errors are printed; | ||
271 | information about the certificate chain is printed on request. | ||
272 | The example is realized for a server that does allow but not require client | ||
273 | certificates. | ||
274 | .Pp | ||
275 | The example makes use of the ex_data technique to store application data | ||
276 | into/retrieve application data from the | ||
277 | .Vt SSL | ||
278 | structure (see | ||
279 | .Xr SSL_get_ex_new_index 3 , | ||
280 | .Xr SSL_get_ex_data_X509_STORE_CTX_idx 3 ) . | ||
281 | .Bd -literal | ||
282 | \&... | ||
283 | |||
284 | typedef struct { | ||
285 | int verbose_mode; | ||
286 | int verify_depth; | ||
287 | int always_continue; | ||
288 | } mydata_t; | ||
289 | int mydata_index; | ||
290 | \&... | ||
291 | static int | ||
292 | verify_callback(int preverify_ok, X509_STORE_CTX *ctx) | ||
293 | { | ||
294 | char buf[256]; | ||
295 | X509 *err_cert; | ||
296 | int err, depth; | ||
297 | SSL *ssl; | ||
298 | mydata_t *mydata; | ||
299 | |||
300 | err_cert = X509_STORE_CTX_get_current_cert(ctx); | ||
301 | err = X509_STORE_CTX_get_error(ctx); | ||
302 | depth = X509_STORE_CTX_get_error_depth(ctx); | ||
303 | |||
304 | /* | ||
305 | * Retrieve the pointer to the SSL of the connection currently | ||
306 | * treated * and the application specific data stored into the | ||
307 | * SSL object. | ||
308 | */ | ||
309 | ssl = X509_STORE_CTX_get_ex_data(ctx, | ||
310 | SSL_get_ex_data_X509_STORE_CTX_idx()); | ||
311 | mydata = SSL_get_ex_data(ssl, mydata_index); | ||
312 | |||
313 | X509_NAME_oneline(X509_get_subject_name(err_cert), buf, 256); | ||
314 | |||
315 | /* | ||
316 | * Catch a too long certificate chain. The depth limit set using | ||
317 | * SSL_CTX_set_verify_depth() is by purpose set to "limit+1" so | ||
318 | * that whenever the "depth>verify_depth" condition is met, we | ||
319 | * have violated the limit and want to log this error condition. | ||
320 | * We must do it here, because the CHAIN_TOO_LONG error would not | ||
321 | * be found explicitly; only errors introduced by cutting off the | ||
322 | * additional certificates would be logged. | ||
323 | */ | ||
324 | if (depth > mydata->verify_depth) { | ||
325 | preverify_ok = 0; | ||
326 | err = X509_V_ERR_CERT_CHAIN_TOO_LONG; | ||
327 | X509_STORE_CTX_set_error(ctx, err); | ||
328 | } | ||
329 | if (!preverify_ok) { | ||
330 | printf("verify error:num=%d:%s:depth=%d:%s\en", err, | ||
331 | X509_verify_cert_error_string(err), depth, buf); | ||
332 | } else if (mydata->verbose_mode) { | ||
333 | printf("depth=%d:%s\en", depth, buf); | ||
334 | } | ||
335 | |||
336 | /* | ||
337 | * At this point, err contains the last verification error. | ||
338 | * We can use it for something special | ||
339 | */ | ||
340 | if (!preverify_ok && (err == | ||
341 | X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT)) { | ||
342 | X509_NAME_oneline(X509_get_issuer_name(ctx->current_cert), | ||
343 | buf, 256); | ||
344 | printf("issuer= %s\en", buf); | ||
345 | } | ||
346 | |||
347 | if (mydata->always_continue) | ||
348 | return 1; | ||
349 | else | ||
350 | return preverify_ok; | ||
351 | } | ||
352 | \&... | ||
353 | |||
354 | mydata_t mydata; | ||
355 | |||
356 | \&... | ||
357 | |||
358 | mydata_index = SSL_get_ex_new_index(0, "mydata index", NULL, NULL, NULL); | ||
359 | |||
360 | \&... | ||
361 | |||
362 | SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER|SSL_VERIFY_CLIENT_ONCE, | ||
363 | verify_callback); | ||
364 | |||
365 | /* | ||
366 | * Let the verify_callback catch the verify_depth error so that we get | ||
367 | * an appropriate error in the logfile. | ||
368 | */ | ||
369 | SSL_CTX_set_verify_depth(verify_depth + 1); | ||
370 | |||
371 | /* | ||
372 | * Set up the SSL specific data into "mydata" and store it into the SSL | ||
373 | * structure. | ||
374 | */ | ||
375 | mydata.verify_depth = verify_depth; ... | ||
376 | SSL_set_ex_data(ssl, mydata_index, &mydata); | ||
377 | |||
378 | \&... | ||
379 | |||
380 | SSL_accept(ssl); /* check of success left out for clarity */ | ||
381 | if (peer = SSL_get_peer_certificate(ssl)) { | ||
382 | if (SSL_get_verify_result(ssl) == X509_V_OK) { | ||
383 | /* The client sent a certificate which verified OK */ | ||
384 | } | ||
385 | } | ||
386 | .Ed | ||
387 | .Sh SEE ALSO | ||
388 | .Xr ssl 3 , | ||
389 | .Xr SSL_CTX_get_verify_mode 3 , | ||
390 | .Xr SSL_CTX_load_verify_locations 3 , | ||
391 | .Xr SSL_CTX_set_cert_verify_callback 3 , | ||
392 | .Xr SSL_get_ex_data_X509_STORE_CTX_idx 3 , | ||
393 | .Xr SSL_get_ex_new_index 3 , | ||
394 | .Xr SSL_get_peer_certificate 3 , | ||
395 | .Xr SSL_get_verify_result 3 , | ||
396 | .Xr SSL_new 3 | ||
397 | .Sh BUGS | ||
398 | In client mode, it is not checked whether the | ||
399 | .Dv SSL_VERIFY_PEER | ||
400 | flag is set, but whether | ||
401 | .Dv SSL_VERIFY_NONE | ||
402 | is not set. | ||
403 | This can lead to unexpected behaviour, if the | ||
404 | .Dv SSL_VERIFY_PEER | ||
405 | and | ||
406 | .Dv SSL_VERIFY_NONE | ||
407 | are not used as required (exactly one must be set at any time). | ||
408 | .Pp | ||
409 | The certificate verification depth set with | ||
410 | .Fn SSL[_CTX]_verify_depth | ||
411 | stops the verification at a certain depth. | ||
412 | The error message produced will be that of an incomplete certificate chain and | ||
413 | not | ||
414 | .Dv X509_V_ERR_CERT_CHAIN_TOO_LONG | ||
415 | as may be expected. | ||