1 /*
2  * Copyright 2008-2019 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the OpenSSL license (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 <openssl/asn1t.h>
11 #include <openssl/pem.h>
12 #include <openssl/x509v3.h>
13 #include <openssl/err.h>
14 #include <openssl/cms.h>
15 #include "cms_local.h"
16 #include "internal/nelem.h"
17 
18 /*-
19  * Attribute flags.
20  * CMS attribute restrictions are discussed in
21  *  - RFC 5652 Section 11.
22  * ESS attribute restrictions are discussed in
23  *  - RFC 2634 Section 1.3.4  AND
24  *  - RFC 5035 Section 5.4
25  */
26 /* This is a signed attribute */
27 #define CMS_ATTR_F_SIGNED         0x01
28 /* This is an unsigned attribute */
29 #define CMS_ATTR_F_UNSIGNED       0x02
30 /* Must be present if there are any other attributes of the same type */
31 #define CMS_ATTR_F_REQUIRED_COND  0x10
32 /* There can only be one instance of this attribute */
33 #define CMS_ATTR_F_ONLY_ONE       0x20
34 /* The Attribute's value must have exactly one entry */
35 #define CMS_ATTR_F_ONE_ATTR_VALUE 0x40
36 
37 /* Attributes rules for different attributes */
38 static const struct {
39     int nid;   /* The attribute id */
40     int flags;
41 } cms_attribute_properties[] = {
42     /* See RFC Section 11 */
43     { NID_pkcs9_contentType, CMS_ATTR_F_SIGNED
44                              | CMS_ATTR_F_ONLY_ONE
45                              | CMS_ATTR_F_ONE_ATTR_VALUE
46                              | CMS_ATTR_F_REQUIRED_COND },
47     { NID_pkcs9_messageDigest, CMS_ATTR_F_SIGNED
48                                | CMS_ATTR_F_ONLY_ONE
49                                | CMS_ATTR_F_ONE_ATTR_VALUE
50                                | CMS_ATTR_F_REQUIRED_COND },
51     { NID_pkcs9_signingTime, CMS_ATTR_F_SIGNED
52                              | CMS_ATTR_F_ONLY_ONE
53                              | CMS_ATTR_F_ONE_ATTR_VALUE },
54     { NID_pkcs9_countersignature, CMS_ATTR_F_UNSIGNED },
55     /* ESS */
56     { NID_id_smime_aa_signingCertificate, CMS_ATTR_F_SIGNED
57                                           | CMS_ATTR_F_ONLY_ONE
58                                           | CMS_ATTR_F_ONE_ATTR_VALUE },
59     { NID_id_smime_aa_signingCertificateV2, CMS_ATTR_F_SIGNED
60                                             | CMS_ATTR_F_ONLY_ONE
61                                             | CMS_ATTR_F_ONE_ATTR_VALUE },
62     { NID_id_smime_aa_receiptRequest, CMS_ATTR_F_SIGNED
63                                       | CMS_ATTR_F_ONLY_ONE
64                                       | CMS_ATTR_F_ONE_ATTR_VALUE }
65 };
66 
67 /* CMS SignedData Attribute utilities */
68 
CMS_signed_get_attr_count(const CMS_SignerInfo * si)69 int CMS_signed_get_attr_count(const CMS_SignerInfo *si)
70 {
71     return X509at_get_attr_count(si->signedAttrs);
72 }
73 
CMS_signed_get_attr_by_NID(const CMS_SignerInfo * si,int nid,int lastpos)74 int CMS_signed_get_attr_by_NID(const CMS_SignerInfo *si, int nid, int lastpos)
75 {
76     return X509at_get_attr_by_NID(si->signedAttrs, nid, lastpos);
77 }
78 
CMS_signed_get_attr_by_OBJ(const CMS_SignerInfo * si,const ASN1_OBJECT * obj,int lastpos)79 int CMS_signed_get_attr_by_OBJ(const CMS_SignerInfo *si, const ASN1_OBJECT *obj,
80                                int lastpos)
81 {
82     return X509at_get_attr_by_OBJ(si->signedAttrs, obj, lastpos);
83 }
84 
CMS_signed_get_attr(const CMS_SignerInfo * si,int loc)85 X509_ATTRIBUTE *CMS_signed_get_attr(const CMS_SignerInfo *si, int loc)
86 {
87     return X509at_get_attr(si->signedAttrs, loc);
88 }
89 
CMS_signed_delete_attr(CMS_SignerInfo * si,int loc)90 X509_ATTRIBUTE *CMS_signed_delete_attr(CMS_SignerInfo *si, int loc)
91 {
92     return X509at_delete_attr(si->signedAttrs, loc);
93 }
94 
CMS_signed_add1_attr(CMS_SignerInfo * si,X509_ATTRIBUTE * attr)95 int CMS_signed_add1_attr(CMS_SignerInfo *si, X509_ATTRIBUTE *attr)
96 {
97     if (X509at_add1_attr(&si->signedAttrs, attr))
98         return 1;
99     return 0;
100 }
101 
CMS_signed_add1_attr_by_OBJ(CMS_SignerInfo * si,const ASN1_OBJECT * obj,int type,const void * bytes,int len)102 int CMS_signed_add1_attr_by_OBJ(CMS_SignerInfo *si,
103                                 const ASN1_OBJECT *obj, int type,
104                                 const void *bytes, int len)
105 {
106     if (X509at_add1_attr_by_OBJ(&si->signedAttrs, obj, type, bytes, len))
107         return 1;
108     return 0;
109 }
110 
CMS_signed_add1_attr_by_NID(CMS_SignerInfo * si,int nid,int type,const void * bytes,int len)111 int CMS_signed_add1_attr_by_NID(CMS_SignerInfo *si,
112                                 int nid, int type, const void *bytes, int len)
113 {
114     if (X509at_add1_attr_by_NID(&si->signedAttrs, nid, type, bytes, len))
115         return 1;
116     return 0;
117 }
118 
CMS_signed_add1_attr_by_txt(CMS_SignerInfo * si,const char * attrname,int type,const void * bytes,int len)119 int CMS_signed_add1_attr_by_txt(CMS_SignerInfo *si,
120                                 const char *attrname, int type,
121                                 const void *bytes, int len)
122 {
123     if (X509at_add1_attr_by_txt(&si->signedAttrs, attrname, type, bytes, len))
124         return 1;
125     return 0;
126 }
127 
CMS_signed_get0_data_by_OBJ(CMS_SignerInfo * si,const ASN1_OBJECT * oid,int lastpos,int type)128 void *CMS_signed_get0_data_by_OBJ(CMS_SignerInfo *si, const ASN1_OBJECT *oid,
129                                   int lastpos, int type)
130 {
131     return X509at_get0_data_by_OBJ(si->signedAttrs, oid, lastpos, type);
132 }
133 
CMS_unsigned_get_attr_count(const CMS_SignerInfo * si)134 int CMS_unsigned_get_attr_count(const CMS_SignerInfo *si)
135 {
136     return X509at_get_attr_count(si->unsignedAttrs);
137 }
138 
CMS_unsigned_get_attr_by_NID(const CMS_SignerInfo * si,int nid,int lastpos)139 int CMS_unsigned_get_attr_by_NID(const CMS_SignerInfo *si, int nid,
140                                  int lastpos)
141 {
142     return X509at_get_attr_by_NID(si->unsignedAttrs, nid, lastpos);
143 }
144 
CMS_unsigned_get_attr_by_OBJ(const CMS_SignerInfo * si,const ASN1_OBJECT * obj,int lastpos)145 int CMS_unsigned_get_attr_by_OBJ(const CMS_SignerInfo *si,
146                                  const ASN1_OBJECT *obj, int lastpos)
147 {
148     return X509at_get_attr_by_OBJ(si->unsignedAttrs, obj, lastpos);
149 }
150 
CMS_unsigned_get_attr(const CMS_SignerInfo * si,int loc)151 X509_ATTRIBUTE *CMS_unsigned_get_attr(const CMS_SignerInfo *si, int loc)
152 {
153     return X509at_get_attr(si->unsignedAttrs, loc);
154 }
155 
CMS_unsigned_delete_attr(CMS_SignerInfo * si,int loc)156 X509_ATTRIBUTE *CMS_unsigned_delete_attr(CMS_SignerInfo *si, int loc)
157 {
158     return X509at_delete_attr(si->unsignedAttrs, loc);
159 }
160 
CMS_unsigned_add1_attr(CMS_SignerInfo * si,X509_ATTRIBUTE * attr)161 int CMS_unsigned_add1_attr(CMS_SignerInfo *si, X509_ATTRIBUTE *attr)
162 {
163     if (X509at_add1_attr(&si->unsignedAttrs, attr))
164         return 1;
165     return 0;
166 }
167 
CMS_unsigned_add1_attr_by_OBJ(CMS_SignerInfo * si,const ASN1_OBJECT * obj,int type,const void * bytes,int len)168 int CMS_unsigned_add1_attr_by_OBJ(CMS_SignerInfo *si,
169                                   const ASN1_OBJECT *obj, int type,
170                                   const void *bytes, int len)
171 {
172     if (X509at_add1_attr_by_OBJ(&si->unsignedAttrs, obj, type, bytes, len))
173         return 1;
174     return 0;
175 }
176 
CMS_unsigned_add1_attr_by_NID(CMS_SignerInfo * si,int nid,int type,const void * bytes,int len)177 int CMS_unsigned_add1_attr_by_NID(CMS_SignerInfo *si,
178                                   int nid, int type,
179                                   const void *bytes, int len)
180 {
181     if (X509at_add1_attr_by_NID(&si->unsignedAttrs, nid, type, bytes, len))
182         return 1;
183     return 0;
184 }
185 
CMS_unsigned_add1_attr_by_txt(CMS_SignerInfo * si,const char * attrname,int type,const void * bytes,int len)186 int CMS_unsigned_add1_attr_by_txt(CMS_SignerInfo *si,
187                                   const char *attrname, int type,
188                                   const void *bytes, int len)
189 {
190     if (X509at_add1_attr_by_txt(&si->unsignedAttrs, attrname,
191                                 type, bytes, len))
192         return 1;
193     return 0;
194 }
195 
CMS_unsigned_get0_data_by_OBJ(CMS_SignerInfo * si,ASN1_OBJECT * oid,int lastpos,int type)196 void *CMS_unsigned_get0_data_by_OBJ(CMS_SignerInfo *si, ASN1_OBJECT *oid,
197                                     int lastpos, int type)
198 {
199     return X509at_get0_data_by_OBJ(si->unsignedAttrs, oid, lastpos, type);
200 }
201 
202 /*
203  * Retrieve an attribute by nid from a stack of attributes starting at index
204  * *lastpos + 1.
205  * Returns the attribute or NULL if there is no attribute.
206  * If an attribute was found *lastpos returns the index of the found attribute.
207  */
cms_attrib_get(int nid,const STACK_OF (X509_ATTRIBUTE)* attrs,int * lastpos)208 static X509_ATTRIBUTE *cms_attrib_get(int nid,
209                                       const STACK_OF(X509_ATTRIBUTE) *attrs,
210                                       int *lastpos)
211 {
212     X509_ATTRIBUTE *at;
213     int loc;
214 
215     loc = X509at_get_attr_by_NID(attrs, nid, *lastpos);
216     if (loc < 0)
217         return NULL;
218 
219     at = X509at_get_attr(attrs, loc);
220     *lastpos = loc;
221     return at;
222 }
223 
cms_check_attribute(int nid,int flags,int type,const STACK_OF (X509_ATTRIBUTE)* attrs,int have_attrs)224 static int cms_check_attribute(int nid, int flags, int type,
225                                const STACK_OF(X509_ATTRIBUTE) *attrs,
226                                int have_attrs)
227 {
228     int lastpos = -1;
229     X509_ATTRIBUTE *at = cms_attrib_get(nid, attrs, &lastpos);
230 
231     if (at != NULL) {
232         int count = X509_ATTRIBUTE_count(at);
233 
234         /* Is this attribute allowed? */
235         if (((flags & type) == 0)
236             /* check if multiple attributes of the same type are allowed */
237             || (((flags & CMS_ATTR_F_ONLY_ONE) != 0)
238                 && cms_attrib_get(nid, attrs, &lastpos) != NULL)
239             /* Check if attribute should have exactly one value in its set */
240             || (((flags & CMS_ATTR_F_ONE_ATTR_VALUE) != 0)
241                 && count != 1)
242             /* There should be at least one value */
243             || count == 0)
244         return 0;
245     } else {
246         /* fail if a required attribute is missing */
247         if (have_attrs
248             && ((flags & CMS_ATTR_F_REQUIRED_COND) != 0)
249             && (flags & type) != 0)
250             return 0;
251     }
252     return 1;
253 }
254 
255 /*
256  * Check that the signerinfo attributes obey the attribute rules which includes
257  * the following checks
258  * - If any signed attributes exist then there must be a Content Type
259  * and Message Digest attribute in the signed attributes.
260  * - The countersignature attribute is an optional unsigned attribute only.
261  * - Content Type, Message Digest, and Signing time attributes are signed
262  *     attributes. Only one instance of each is allowed, with each of these
263  *     attributes containing a single attribute value in its set.
264  */
CMS_si_check_attributes(const CMS_SignerInfo * si)265 int CMS_si_check_attributes(const CMS_SignerInfo *si)
266 {
267     int i;
268     int have_signed_attrs = (CMS_signed_get_attr_count(si) > 0);
269     int have_unsigned_attrs = (CMS_unsigned_get_attr_count(si) > 0);
270 
271     for (i = 0; i < (int)OSSL_NELEM(cms_attribute_properties); ++i) {
272         int nid = cms_attribute_properties[i].nid;
273         int flags = cms_attribute_properties[i].flags;
274 
275         if (!cms_check_attribute(nid, flags, CMS_ATTR_F_SIGNED,
276                                  si->signedAttrs, have_signed_attrs)
277             || !cms_check_attribute(nid, flags, CMS_ATTR_F_UNSIGNED,
278                                     si->unsignedAttrs, have_unsigned_attrs)) {
279             CMSerr(CMS_F_CMS_SI_CHECK_ATTRIBUTES, CMS_R_ATTRIBUTE_ERROR);
280             return 0;
281         }
282     }
283     return 1;
284 }
285