source: libabac/abac_verifier.c @ 2ef48fa

abac0-leakabac0-meicompt_changesgec13mei-idmei-rt0-nmei_rt0mei_rt2mei_rt2_fix_1meiyap-rt1meiyap1rt2tvf-new-xml
Last change on this file since 2ef48fa was 2ef48fa, checked in by Mike Ryan <mikeryan@…>, 14 years ago

use subjectKeyIdentifier instead of SHA1 of entire public key

  • Property mode set to 100644
File size: 8.1 KB
Line 
1#include <assert.h>
2
3#include <library.h>
4#include <credentials/certificates/certificate.h>
5#include <credentials/certificates/x509.h>
6#include <credentials/certificates/ac.h>
7
8#include "abac_verifier.h"
9
10#include "abac_util.h"
11
12typedef struct _abac_id_cert_t {
13    char *keyid;
14    certificate_t *cert;
15
16    UT_hash_handle hh;
17} abac_id_cert_t;
18
19struct _abac_credential_t {
20    abac_role_t *head;
21    abac_role_t *tail;
22    certificate_t *cert;
23    certificate_t *issuer;
24
25    int refcount;
26};
27
28abac_id_cert_t *id_certs = NULL;
29
30// convert a chunk to a lowercase binary string
31// malloc's the string
32static char *_chunk_to_string(chunk_t chunk) {
33    int i;
34
35    char *ret = abac_xmalloc(chunk.len * 2 + 1);
36
37    for (i = 0; i < chunk.len; ++i)
38        sprintf(ret + 2 * i, "%02x", chunk.ptr[i]);
39
40    return ret;
41}
42
43// verify that cert was issued by issuer
44// cert and issuer can be the same, in which case the self-sig is validated
45static int _verify_signature(certificate_t *issuer, certificate_t *cert) {
46    // XXX make sure this checks signature
47    if (cert->issued_by(cert, issuer))
48        if (cert->get_validity(cert, NULL, NULL, NULL))
49            return 1;
50    return 0;
51}
52
53/**
54 * Init the verifier subsystem.
55 */
56void abac_verifier_init(void) {
57    atexit(library_deinit);
58
59    // silence all debugging
60    dbg_default_set_level(-1);
61
62    if (!library_init(NULL))
63        exit(SS_RC_LIBSTRONGSWAN_INTEGRITY);
64
65    if (!lib->plugins->load(lib->plugins, NULL,
66            lib->settings->get_str(lib->settings, "pki.load", PLUGINS)))
67        exit(SS_RC_INITIALIZATION_FAILED);
68}
69
70/**
71 * Uninitialize the system, free up any allocated memory.
72 */
73void abac_verifier_deinit(void) {
74    abac_id_cert_t *id;
75
76    while ((id = id_certs) != NULL) {
77        HASH_DEL(id_certs, id);
78
79        free(id->keyid);
80        id->cert->destroy(id->cert);
81        free(id);
82    }
83}
84
85/**
86 * Load an ID certificate.
87 */
88static int _load_id(certificate_t *cert) {
89    abac_id_cert_t *id_cert = NULL;
90    char *keyid = NULL;
91    chunk_t id;
92    int ret;
93    x509_t *x509 = (x509_t *)cert;
94
95    assert(cert != NULL);
96
97    // get the key ID
98    id = x509->get_subjectKeyIdentifier(x509);
99    keyid = _chunk_to_string(id);
100
101    // if we already have this cert 'error' with success
102    HASH_FIND_STR(id_certs, keyid, id_cert);
103    if (id_cert != NULL) {
104        ret = ABAC_CERT_SUCCESS;
105        goto error;
106    }
107
108    // validate sig
109    ret = _verify_signature(cert, cert);
110    if (!ret) {
111        ret = ABAC_CERT_BAD_SIG;
112        goto error;
113    }
114
115    // success, add the key to the map of certificates
116    id_cert = abac_xmalloc(sizeof(abac_id_cert_t));
117    id_cert->keyid = keyid;
118    id_cert->cert = cert;
119    HASH_ADD_KEYPTR(hh, id_certs, id_cert->keyid, strlen(id_cert->keyid), id_cert);
120
121    return ABAC_CERT_SUCCESS;
122
123error:
124    if (keyid != NULL) free(keyid);
125
126    return ret;
127}
128
129/**
130 * Load an ID cert from a file.
131 */
132int abac_verifier_load_id_file(char *filename) {
133    if (lib == NULL)
134        errx(1, "looks like you didn't call libabac_init() (lib is NULL)");
135
136    // load the cert
137    certificate_t *cert = lib->creds->create(
138        lib->creds, CRED_CERTIFICATE, CERT_X509,
139        BUILD_FROM_FILE, filename,
140        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
141        BUILD_END
142    );
143    if (cert == NULL)
144        return ABAC_CERT_INVALID;
145    return _load_id(cert);
146}
147
148/**
149 * Load an ID cert from a chunk.
150 */
151int abac_verifier_load_id_chunk(chunk_t chunk) {
152    // load the cert
153    certificate_t *cert = lib->creds->create(
154        lib->creds, CRED_CERTIFICATE, CERT_X509,
155        BUILD_BLOB_ASN1_DER, chunk,
156        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
157        BUILD_END
158    );
159    if (cert == NULL)
160        return ABAC_CERT_INVALID;
161    return _load_id(cert);
162}
163
164/**
165 * Load an attribute cert.
166 * Returns true only if the certificate is valid and is issued by the proper
167 * authority.
168 */
169static int _load_attribute_cert(certificate_t *cert, abac_credential_t **cred_ret) {
170    ietf_attributes_t *attr_cert = NULL;
171    abac_role_t *head_role = NULL;
172    abac_role_t *tail_role = NULL;
173    abac_id_cert_t *issuer;
174    int ret;
175
176    // get the attr
177    ac_t *ac = (ac_t *)cert;
178    attr_cert = ac->get_groups(ac);
179    if (attr_cert == NULL) {
180        ret = ABAC_CERT_INVALID;
181        goto error;
182    }
183
184    char *attr_string = attr_cert->get_string(attr_cert);
185    if (attr_string == NULL) {
186        ret = ABAC_CERT_INVALID;
187        goto error;
188    }
189
190    // split into head/tail parts
191    char head[256], tail[256];
192    ret = sscanf(attr_string, "%255s <- %255s", head, tail);
193    if (ret != 2) {
194        ret = ABAC_CERT_INVALID;
195        goto error;
196    }
197
198    // must be a role
199    head_role = abac_role_from_string(head);
200    if (head_role == NULL) goto error;
201    if (!abac_role_is_role(head_role)) {
202        ret = ABAC_CERT_INVALID;
203        goto error;
204    }
205
206    // make sure the tail role is valid
207    tail_role = abac_role_from_string(tail);
208    if (tail_role == NULL) {
209        ret = ABAC_CERT_INVALID;
210        goto error;
211    }
212
213    // get the issuer based on keyid
214    char *principal = abac_role_principal(head_role);
215    HASH_FIND_STR(id_certs, principal, issuer);
216    if (issuer == NULL) {
217        ret = ABAC_CERT_MISSING_ISSUER;
218        goto error;
219    }
220
221    // make sure the issuer's signed it
222    ret = _verify_signature(issuer->cert, cert);
223    if (!ret) {
224        ret = ABAC_CERT_BAD_SIG;
225        goto error;
226    }
227
228    // at this point we know we have a good attribute cert
229    abac_credential_t *cred = abac_xmalloc(sizeof(abac_credential_t));
230    cred->head = head_role;
231    cred->tail = tail_role;
232    cred->cert = cert;
233    cred->issuer = issuer->cert->get_ref(issuer->cert);
234    cred->refcount = 1;
235    *cred_ret = cred;
236
237    // free up some crap
238    attr_cert->destroy(attr_cert);
239
240    return ABAC_CERT_SUCCESS;
241
242error:
243    if (cert != NULL) cert->destroy(cert);
244    if (attr_cert != NULL) attr_cert->destroy(attr_cert);
245    if (head_role != NULL) abac_role_free(head_role);
246    if (tail_role != NULL) abac_role_free(tail_role);
247
248    return ret;
249}
250
251/**
252 * Load an attribute cert from a file.
253 */
254int abac_verifier_load_attribute_cert_file(char *filename, abac_credential_t **cred) {
255    // load the cert
256    certificate_t *cert = lib->creds->create(
257        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
258        BUILD_FROM_FILE, filename,
259        BUILD_END
260    );
261    if (cert == NULL)
262        return ABAC_CERT_INVALID;
263    return _load_attribute_cert(cert, cred);
264}
265
266/**
267 * Load an attribute cert from a chunk.
268 */
269int abac_verifier_load_attribute_cert_chunk(chunk_t chunk, abac_credential_t **cred) {
270    // load the cert
271    certificate_t *cert = lib->creds->create(
272        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
273        BUILD_BLOB_ASN1_DER, chunk,
274        BUILD_END
275    );
276    if (cert == NULL)
277        return ABAC_CERT_INVALID;
278    return _load_attribute_cert(cert, cred);
279}
280
281/**
282 * Return the head role.
283 */
284abac_role_t *abac_credential_head(abac_credential_t *cred) {
285    return cred->head;
286}
287
288/**
289 * Return the tail role.
290 */
291abac_role_t *abac_credential_tail(abac_credential_t *cred) {
292    return cred->tail;
293}
294
295/**
296 * Return the encoding of the attribute cert.
297 */
298abac_chunk_t abac_credential_attribute_cert(abac_credential_t *cred) {
299    chunk_t encoding = cred->cert->get_encoding(cred->cert);
300    abac_chunk_t ret = { encoding.ptr, encoding.len };
301    return ret;
302}
303
304/**
305 * Return the encoding of the issuer cert.
306 */
307abac_chunk_t abac_credential_issuer_cert(abac_credential_t *cred) {
308    chunk_t encoding = cred->issuer->get_encoding(cred->issuer);
309    abac_chunk_t ret = { encoding.ptr, encoding.len };
310    return ret;
311}
312
313/**
314 * Increase the ref count of a credential.
315 */
316abac_credential_t *abac_credential_dup(abac_credential_t *cred) {
317    assert(cred != NULL);
318
319    ++cred->refcount;
320    return cred;
321}
322
323/**
324 * Decrease the reference count of a credential, freeing it when it reaches 0.
325 */
326void abac_credential_free(abac_credential_t *cred) {
327    if (cred == NULL)
328        return;
329
330    --cred->refcount;
331    if (cred->refcount > 0)
332        return;
333
334    abac_role_free(cred->head);
335    abac_role_free(cred->tail);
336    cred->cert->destroy(cred->cert);
337    cred->issuer->destroy(cred->issuer); // reference counted
338
339    free(cred);
340}
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