crypto/x509/x509_trs.c

   1 /*
   2  * Copyright 1999-2020 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 DEFINE_STACK_OF(X509_TRUST)
  16 DEFINE_STACK_OF(ASN1_OBJECT)
  17
  18 static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b);
  19 static void trtable_free(X509_TRUST *p);
  20
  21 static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags);
  22 static int trust_1oid(X509_TRUST *trust, X509 *x, int flags);
  23 static int trust_compat(X509_TRUST *trust, X509 *x, int flags);
  24
  25 static int obj_trust(int id, X509 *x, int flags);
  26 static int (*default_trust) (int id, X509 *x, int flags) = obj_trust;
  27
  28 /*
  29  * WARNING: the following table should be kept in order of trust and without
  30  * any gaps so we can just subtract the minimum trust value to get an index
  31  * into the table
  32  */
  33
  34 static X509_TRUST trstandard[] = {
  35     {X509_TRUST_COMPAT, 0, trust_compat, "compatible", 0, NULL},
  36     {X509_TRUST_SSL_CLIENT, 0, trust_1oidany, "SSL Client", NID_client_auth,
  37      NULL},
  38     {X509_TRUST_SSL_SERVER, 0, trust_1oidany, "SSL Server", NID_server_auth,
  39      NULL},
  40     {X509_TRUST_EMAIL, 0, trust_1oidany, "S/MIME email", NID_email_protect,
  41      NULL},
  42     {X509_TRUST_OBJECT_SIGN, 0, trust_1oidany, "Object Signer", NID_code_sign,
  43      NULL},
  44     {X509_TRUST_OCSP_SIGN, 0, trust_1oid, "OCSP responder", NID_OCSP_sign,
  45      NULL},
  46     {X509_TRUST_OCSP_REQUEST, 0, trust_1oid, "OCSP request", NID_ad_OCSP,
  47      NULL},
  48     {X509_TRUST_TSA, 0, trust_1oidany, "TSA server", NID_time_stamp, NULL}
  49 };
  50
  51 #define X509_TRUST_COUNT        OSSL_NELEM(trstandard)
  52
  53 static STACK_OF(X509_TRUST) *trtable = NULL;
  54
  55 static int tr_cmp(const X509_TRUST *const *a, const X509_TRUST *const *b)
  56 {
  57     return (*a)->trust - (*b)->trust;
  58 }
  59
  60 int (*X509_TRUST_set_default(int (*trust) (int, X509 *, int))) (int, X509 *,
  61                                                                 int) {
  62     int (*oldtrust) (int, X509 *, int);
  63     oldtrust = default_trust;
  64     default_trust = trust;
  65     return oldtrust;
  66 }
  67
  68 int X509_check_trust(X509 *x, int id, int flags)
  69 {
  70     X509_TRUST *pt;
  71     int idx;
  72
  73     /* We get this as a default value */
  74     if (id == X509_TRUST_DEFAULT)
  75         return obj_trust(NID_anyExtendedKeyUsage, x,
  76                          flags | X509_TRUST_DO_SS_COMPAT);
  77     idx = X509_TRUST_get_by_id(id);
  78     if (idx == -1)
  79         return default_trust(id, x, flags);
  80     pt = X509_TRUST_get0(idx);
  81     return pt->check_trust(pt, x, flags);
  82 }
  83
  84 int X509_TRUST_get_count(void)
  85 {
  86     if (!trtable)
  87         return X509_TRUST_COUNT;
  88     return sk_X509_TRUST_num(trtable) + X509_TRUST_COUNT;
  89 }
  90
  91 X509_TRUST *X509_TRUST_get0(int idx)
  92 {
  93     if (idx < 0)
  94         return NULL;
  95     if (idx < (int)X509_TRUST_COUNT)
  96         return trstandard + idx;
  97     return sk_X509_TRUST_value(trtable, idx - X509_TRUST_COUNT);
  98 }
  99
 100 int X509_TRUST_get_by_id(int id)
 101 {
 102     X509_TRUST tmp;
 103     int idx;
 104
 105     if ((id >= X509_TRUST_MIN) && (id <= X509_TRUST_MAX))
 106         return id - X509_TRUST_MIN;
 107     if (trtable == NULL)
 108         return -1;
 109     tmp.trust = id;
 110     idx = sk_X509_TRUST_find(trtable, &tmp);
 111     if (idx < 0)
 112         return -1;
 113     return idx + X509_TRUST_COUNT;
 114 }
 115
 116 int X509_TRUST_set(int *t, int trust)
 117 {
 118     if (X509_TRUST_get_by_id(trust) == -1) {
 119         X509err(X509_F_X509_TRUST_SET, X509_R_INVALID_TRUST);
 120         return 0;
 121     }
 122     *t = trust;
 123     return 1;
 124 }
 125
 126 int X509_TRUST_add(int id, int flags, int (*ck) (X509_TRUST *, X509 *, int),
 127                    const char *name, int arg1, void *arg2)
 128 {
 129     int idx;
 130     X509_TRUST *trtmp;
 131     /*
 132      * This is set according to what we change: application can't set it
 133      */
 134     flags &= ~X509_TRUST_DYNAMIC;
 135     /* This will always be set for application modified trust entries */
 136     flags |= X509_TRUST_DYNAMIC_NAME;
 137     /* Get existing entry if any */
 138     idx = X509_TRUST_get_by_id(id);
 139     /* Need a new entry */
 140     if (idx == -1) {
 141         if ((trtmp = OPENSSL_malloc(sizeof(*trtmp))) == NULL) {
 142             X509err(X509_F_X509_TRUST_ADD, ERR_R_MALLOC_FAILURE);
 143             return 0;
 144         }
 145         trtmp->flags = X509_TRUST_DYNAMIC;
 146     } else
 147         trtmp = X509_TRUST_get0(idx);
 148
 149     /* OPENSSL_free existing name if dynamic */
 150     if (trtmp->flags & X509_TRUST_DYNAMIC_NAME)
 151         OPENSSL_free(trtmp->name);
 152     /* dup supplied name */
 153     if ((trtmp->name = OPENSSL_strdup(name)) == NULL) {
 154         X509err(X509_F_X509_TRUST_ADD, ERR_R_MALLOC_FAILURE);
 155         goto err;
 156     }
 157     /* Keep the dynamic flag of existing entry */
 158     trtmp->flags &= X509_TRUST_DYNAMIC;
 159     /* Set all other flags */
 160     trtmp->flags |= flags;
 161
 162     trtmp->trust = id;
 163     trtmp->check_trust = ck;
 164     trtmp->arg1 = arg1;
 165     trtmp->arg2 = arg2;
 166
 167     /* If its a new entry manage the dynamic table */
 168     if (idx == -1) {
 169         if (trtable == NULL
 170             && (trtable = sk_X509_TRUST_new(tr_cmp)) == NULL) {
 171             X509err(X509_F_X509_TRUST_ADD, ERR_R_MALLOC_FAILURE);
 172             goto err;;
 173         }
 174         if (!sk_X509_TRUST_push(trtable, trtmp)) {
 175             X509err(X509_F_X509_TRUST_ADD, ERR_R_MALLOC_FAILURE);
 176             goto err;
 177         }
 178     }
 179     return 1;
 180  err:
 181     if (idx == -1) {
 182         OPENSSL_free(trtmp->name);
 183         OPENSSL_free(trtmp);
 184     }
 185     return 0;
 186 }
 187
 188 static void trtable_free(X509_TRUST *p)
 189 {
 190     if (p == NULL)
 191         return;
 192     if (p->flags & X509_TRUST_DYNAMIC) {
 193         if (p->flags & X509_TRUST_DYNAMIC_NAME)
 194             OPENSSL_free(p->name);
 195         OPENSSL_free(p);
 196     }
 197 }
 198
 199 void X509_TRUST_cleanup(void)
 200 {
 201     sk_X509_TRUST_pop_free(trtable, trtable_free);
 202     trtable = NULL;
 203 }
 204
 205 int X509_TRUST_get_flags(const X509_TRUST *xp)
 206 {
 207     return xp->flags;
 208 }
 209
 210 char *X509_TRUST_get0_name(const X509_TRUST *xp)
 211 {
 212     return xp->name;
 213 }
 214
 215 int X509_TRUST_get_trust(const X509_TRUST *xp)
 216 {
 217     return xp->trust;
 218 }
 219
 220 static int trust_1oidany(X509_TRUST *trust, X509 *x, int flags)
 221 {
 222     /*
 223      * Declare the chain verified if the desired trust OID is not rejected in
 224      * any auxiliary trust info for this certificate, and the OID is either
 225      * expressly trusted, or else either "anyEKU" is trusted, or the
 226      * certificate is self-signed.
 227      */
 228     flags |= X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU;
 229     return obj_trust(trust->arg1, x, flags);
 230 }
 231
 232 static int trust_1oid(X509_TRUST *trust, X509 *x, int flags)
 233 {
 234     /*
 235      * Declare the chain verified only if the desired trust OID is not
 236      * rejected and is expressly trusted.  Neither "anyEKU" nor "compat"
 237      * trust in self-signed certificates apply.
 238      */
 239     flags &= ~(X509_TRUST_DO_SS_COMPAT | X509_TRUST_OK_ANY_EKU);
 240     return obj_trust(trust->arg1, x, flags);
 241 }
 242
 243 static int trust_compat(X509_TRUST *trust, X509 *x, int flags)
 244 {
 245     /* Call for side-effect of computing hash and caching extensions */
 246     if (X509_check_purpose(x, -1, 0) != 1)
 247         return X509_TRUST_UNTRUSTED;
 248     if ((flags & X509_TRUST_NO_SS_COMPAT) == 0 && (x->ex_flags & EXFLAG_SS))
 249         return X509_TRUST_TRUSTED;
 250     else
 251         return X509_TRUST_UNTRUSTED;
 252 }
 253
 254 static int obj_trust(int id, X509 *x, int flags)
 255 {
 256     X509_CERT_AUX *ax = x->aux;
 257     int i;
 258
 259     if (ax && ax->reject) {
 260         for (i = 0; i < sk_ASN1_OBJECT_num(ax->reject); i++) {
 261             ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->reject, i);
 262             int nid = OBJ_obj2nid(obj);
 263
 264             if (nid == id || (nid == NID_anyExtendedKeyUsage &&
 265                 (flags & X509_TRUST_OK_ANY_EKU)))
 266                 return X509_TRUST_REJECTED;
 267         }
 268     }
 269
 270     if (ax && ax->trust) {
 271         for (i = 0; i < sk_ASN1_OBJECT_num(ax->trust); i++) {
 272             ASN1_OBJECT *obj = sk_ASN1_OBJECT_value(ax->trust, i);
 273             int nid = OBJ_obj2nid(obj);
 274
 275             if (nid == id || (nid == NID_anyExtendedKeyUsage &&
 276                 (flags & X509_TRUST_OK_ANY_EKU)))
 277                 return X509_TRUST_TRUSTED;
 278         }
 279         /*
 280          * Reject when explicit trust EKU are set and none match.
 281          *
 282          * Returning untrusted is enough for for full chains that end in
 283          * self-signed roots, because when explicit trust is specified it
 284          * suppresses the default blanket trust of self-signed objects.
 285          *
 286          * But for partial chains, this is not enough, because absent a similar
 287          * trust-self-signed policy, non matching EKUs are indistinguishable
 288          * from lack of EKU constraints.
 289          *
 290          * Therefore, failure to match any trusted purpose must trigger an
 291          * explicit reject.
 292          */
 293         return X509_TRUST_REJECTED;
 294     }
 295
 296     if ((flags & X509_TRUST_DO_SS_COMPAT) == 0)
 297         return X509_TRUST_UNTRUSTED;
 298
 299     /*
 300      * Not rejected, and there is no list of accepted uses, try compat.
 301      */
 302     return trust_compat(NULL, x, flags);
 303 }