crypto/x509/x509_trust.c

   1 /*
   2  * Copyright 1999-2022 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include "internal/cryptlib.h"
  12 #include <openssl/x509v3.h>
  13 #include "crypto/x509.h"
  14
  15 static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b);
  16 static void trtable_free(X509_TRUST *p);
  17
  18 static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags);
  19 static int trust_1oid(X509_TRUST *trust, X509 *x, int flags);
  20 static int trust_compat(X509_TRUST *trust, X509 *x, int flags);
  21
  22 static int obj_trust(int id, X509 *x, int flags);
  23 static int (*default_trust) (int id, X509 *x, int flags) = obj_trust;
  24
  25 /*
  26  * WARNING: the following table should be kept in order of trust and without
  27  * any gaps so we can just subtract the minimum trust value to get an index
  28  * into the table
  29  */
  30
  31 static X509_TRUST trstandard[] = {
  32     {X509_TRUST_COMPAT, 0, trust_compat, "compatible", 0, NULL},
  33     {X509_TRUST_SSL_CLIENT, 0, trust_1oidany, "SSL Client", NID_client_auth,
  34      NULL},
  35     {X509_TRUST_SSL_SERVER, 0, trust_1oidany, "SSL Server", NID_server_auth,
  36      NULL},
  37     {X509_TRUST_EMAIL, 0, trust_1oidany, "S/MIME email", NID_email_protect,
  38      NULL},
  39     {X509_TRUST_OBJECT_SIGN, 0, trust_1oidany, "Object Signer", NID_code_sign,
  40      NULL},
  41     {X509_TRUST_OCSP_SIGN, 0, trust_1oid, "OCSP responder", NID_OCSP_sign,
  42      NULL},
  43     {X509_TRUST_OCSP_REQUEST, 0, trust_1oid, "OCSP request", NID_ad_OCSP,
  44      NULL},
  45     {X509_TRUST_TSA, 0, trust_1oidany, "TSA server", NID_time_stamp, NULL}
  46 };
  47
  48 #define X509_TRUST_COUNT        OSSL_NELEM(trstandard)
  49
  50 static STACK_OF(X509_TRUST) *trtable = NULL;
  51
  52 static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b)
  53 {
  54     return (*a)->trust - (*b)->trust;
  55 }
  56
  57 int (*X509_TRUST_set_default(int (*trust) (int, X509 *, int))) (int, X509 *,
  58                                                                 int) {
  59     int (*oldtrust) (int, X509 *, int);
  60     oldtrust = default_trust;
  61     default_trust = trust;
  62     return oldtrust;
  63 }
  64
  65 /* Returns X509_TRUST_TRUSTED, X509_TRUST_REJECTED, or X509_TRUST_UNTRUSTED */
  66 int X509_check_trust(X509 *x, int id, int flags)
  67 {
  68     X509_TRUST *pt;
  69     int idx;
  70
  71     /* We get this as a default value */
  72     if (id == X509_TRUST_DEFAULT)
  73         return obj_trust(NID_anyExtendedKeyUsage, x,
  74                          flags | X509_TRUST_DO_SS_COMPAT);
  75     idx = X509_TRUST_get_by_id(id);
  76     if (idx < 0)
  77         return default_trust(id, x, flags);
  78     pt = X509_TRUST_get0(idx);
  79     return pt->check_trust(pt, x, flags);
  80 }
  81
  82 int X509_TRUST_get_count(void)
  83 {
  84     if (!trtable)
  85         return X509_TRUST_COUNT;
  86     return sk_X509_TRUST_num(trtable) + X509_TRUST_COUNT;
  87 }
  88
  89 X509_TRUST *X509_TRUST_get0(int idx)
  90 {
  91     if (idx < 0)
  92         return NULL;
  93     if (idx < (int)X509_TRUST_COUNT)
  94         return trstandard + idx;
  95     return sk_X509_TRUST_value(trtable, idx - X509_TRUST_COUNT);
  96 }
  97
  98 int X509_TRUST_get_by_id(int id)
  99 {
 100     X509_TRUST tmp;
 101     int idx;
 102
 103     if ((id >= X509_TRUST_MIN) && (id <= X509_TRUST_MAX))
 104         return id - X509_TRUST_MIN;
 105     if (trtable == NULL)
 106         return -1;
 107     tmp.trust = id;
 108     idx = sk_X509_TRUST_find(trtable, &tmp);
 109     if (idx < 0)
 110         return -1;
 111     return idx + X509_TRUST_COUNT;
 112 }
 113
 114 int X509_TRUST_set(int *t, int trust)
 115 {
 116     if (X509_TRUST_get_by_id(trust) < 0) {
 117         ERR_raise(ERR_LIB_X509, X509_R_INVALID_TRUST);
 118         return 0;
 119     }
 120     *t = trust;
 121     return 1;
 122 }
 123
 124 int X509_TRUST_add(int id, int flags, int (*ck) (X509_TRUST *, X509 *, int),
 125                    const char *name, int arg1, void *arg2)
 126 {
 127     int idx;
 128     X509_TRUST *trtmp;
 129     /*
 130      * This is set according to what we change: application can't set it
 131      */
 132     flags &= ~X509_TRUST_DYNAMIC;
 133     /* This will always be set for application modified trust entries */
 134     flags |= X509_TRUST_DYNAMIC_NAME;
 135     /* Get existing entry if any */
 136     idx = X509_TRUST_get_by_id(id);
 137     /* Need a new entry */
 138     if (idx < 0) {
 139         if ((trtmp = OPENSSL_malloc(sizeof(*trtmp))) == NULL) {
 140             ERR_raise(ERR_LIB_X509, ERR_R_MALLOC_FAILURE);
 141             return 0;
 142         }
 143         trtmp->flags = X509_TRUST_DYNAMIC;
 144     } else
 145         trtmp = X509_TRUST_get0(idx);
 146
 147     /* OPENSSL_free existing name if dynamic */
 148     if (trtmp->flags & X509_TRUST_DYNAMIC_NAME)
 149         OPENSSL_free(trtmp->name);
 150     /* dup supplied name */
 151     if ((trtmp->name = OPENSSL_strdup(name)) == NULL) {
 152         ERR_raise(ERR_LIB_X509, ERR_R_MALLOC_FAILURE);
 153         goto err;
 154     }
 155     /* Keep the dynamic flag of existing entry */
 156     trtmp->flags &= X509_TRUST_DYNAMIC;
 157     /* Set all other flags */
 158     trtmp->flags |= flags;
 159
 160     trtmp->trust = id;
 161     trtmp->check_trust = ck;
 162     trtmp->arg1 = arg1;
 163     trtmp->arg2 = arg2;
 164
 165     /* If its a new entry manage the dynamic table */
 166     if (idx < 0) {
 167         if (trtable == NULL
 168             && (trtable = sk_X509_TRUST_new(tr_cmp)) == NULL) {
 169             ERR_raise(ERR_LIB_X509, ERR_R_MALLOC_FAILURE);
 170             goto err;
 171         }
 172         if (!sk_X509_TRUST_push(trtable, trtmp)) {
 173             ERR_raise(ERR_LIB_X509, ERR_R_MALLOC_FAILURE);
 174             goto err;
 175         }
 176     }
 177     return 1;
 178  err:
 179     if (idx < 0) {
 180         OPENSSL_free(trtmp->name);
 181         OPENSSL_free(trtmp);
 182     }
 183     return 0;
 184 }
 185
 186 static void trtable_free(X509_TRUST *p)
 187 {
 188     if (p == NULL)
 189         return;
 190     if (p->flags & X509_TRUST_DYNAMIC) {
 191         if (p->flags & X509_TRUST_DYNAMIC_NAME)
 192             OPENSSL_free(p->name);
 193         OPENSSL_free(p);
 194     }
 195 }
 196
 197 void X509_TRUST_cleanup(void)
 198 {
 199     sk_X509_TRUST_pop_free(trtable, trtable_free);
 200     trtable = NULL;
 201 }
 202
 203 int X509_TRUST_get_flags(const X509_TRUST *xp)
 204 {
 205     return xp->flags;
 206 }
 207
 208 char *X509_TRUST_get0_name(const X509_TRUST *xp)
 209 {
 210     return xp->name;
 211 }
 212
 213 int X509_TRUST_get_trust(const X509_TRUST *xp)
 214 {
 215     return xp->trust;
 216 }
 217
 218 static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags)
 219 {
 220     /*
 221      * Declare the chain verified if the desired trust OID is not rejected in
 222      * any auxiliary trust info for this certificate, and the OID is either
 223      * expressly trusted, or else either "anyEKU" is trusted, or the
 224      * certificate is self-signed and X509_TRUST_NO_SS_COMPAT is not set.
 225      */
 226     flags |= X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU;
 227     return obj_trust(trust->arg1, x, flags);
 228 }
 229
 230 static int trust_1oid(X509_TRUST *trust, X509 *x, int flags)
 231 {
 232     /*
 233      * Declare the chain verified only if the desired trust OID is not
 234      * rejected and is expressly trusted.  Neither "anyEKU" nor "compat"
 235      * trust in self-signed certificates apply.
 236      */
 237     flags &= ~(X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU);
 238     return obj_trust(trust->arg1, x, flags);
 239 }
 240
 241 static int trust_compat(X509_TRUST *trust, X509 *x, int flags)
 242 {
 243     /* Call for side-effect of setting EXFLAG_SS for self-signed-certs */
 244     if (X509_check_purpose(x, -1, 0) != 1)
 245         return X509_TRUST_UNTRUSTED;
 246     if ((flags & X509_TRUST_NO_SS_COMPAT) == 0 && (x->ex_flags & EXFLAG_SS))
 247         return X509_TRUST_TRUSTED;
 248     else
 249         return X509_TRUST_UNTRUSTED;
 250 }
 251
 252 static int obj_trust(int id, X509 *x, int flags)
 253 {
 254     X509_CERT_AUX *ax = x->aux;
 255     int i;
 256
 257     if (ax != NULL && ax->reject != NULL) {
 258         for (i = 0; i < sk_ASN1_OBJECT_num(ax->reject); i++) {
 259             ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->reject, i);
 260             int nid = OBJ_obj2nid(obj);
 261
 262             if (nid == id || (nid == NID_anyExtendedKeyUsage &&
 263                 (flags & X509_TRUST_OK_ANY_EKU)))
 264                 return X509_TRUST_REJECTED;
 265         }
 266     }
 267
 268     if (ax != NULL && ax->trust != NULL) {
 269         for (i = 0; i < sk_ASN1_OBJECT_num(ax->trust); i++) {
 270             ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->trust, i);
 271             int nid = OBJ_obj2nid(obj);
 272
 273             if (nid == id || (nid == NID_anyExtendedKeyUsage &&
 274                 (flags & X509_TRUST_OK_ANY_EKU)))
 275                 return X509_TRUST_TRUSTED;
 276         }
 277         /*
 278          * Reject when explicit trust EKU are set and none match.
 279          *
 280          * Returning untrusted is enough for for full chains that end in
 281          * self-signed roots, because when explicit trust is specified it
 282          * suppresses the default blanket trust of self-signed objects.
 283          *
 284          * But for partial chains, this is not enough, because absent a similar
 285          * trust-self-signed policy, non matching EKUs are indistinguishable
 286          * from lack of EKU constraints.
 287          *
 288          * Therefore, failure to match any trusted purpose must trigger an
 289          * explicit reject.
 290          */
 291         return X509_TRUST_REJECTED;
 292     }
 293
 294     if ((flags & X509_TRUST_DO_SS_COMPAT) == 0)
 295         return X509_TRUST_UNTRUSTED;
 296
 297     /*
 298      * Not rejected, and there is no list of accepted uses, try compat.
 299      */
 300     return trust_compat(NULL, x, flags);
 301 }