Add functions to parse and generate PKCS#7 files with CRLs.

(This is a cherry-pick of upstream BoringSSL's
50073e8c5e81d8151718e05ec54b7c213372b878.)

Change-Id: Id29ea889055dbecfbba4fc4a9e01af0c49b8073e

4 files changed, 334 insertions, 23 deletions

diff --git a/src/crypto/x509/pkcs7.c b/src/crypto/x509/pkcs7.c
index 75c101b..9a4e490 100644
--- a/src/crypto/x509/pkcs7.c
+++ b/src/crypto/x509/pkcs7.c
@@ -14,6 +14,8 @@
 
 #include <openssl/x509.h>
 
+#include <assert.h>
+
 #include <openssl/bytestring.h>
 #include <openssl/err.h>
 #include <openssl/obj.h>
@@ -22,21 +24,26 @@
 #include "../bytestring/internal.h"
 
 
-int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
-  uint8_t *der_bytes = NULL;
+/* pkcs7_parse_header reads the non-certificate/non-CRL prefix of a PKCS#7
+ * SignedData blob from |cbs| and sets |*out| to point to the rest of the
+ * input. If the input is in BER format, then |*der_bytes| will be set to a
+ * pointer that needs to be freed by the caller once they have finished
+ * processing |*out| (which will be pointing into |*der_bytes|).
+ *
+ * It returns one on success or zero on error. On error, |*der_bytes| is
+ * NULL. */
+static int pkcs7_parse_header(uint8_t **der_bytes, CBS *out, CBS *cbs) {
   size_t der_len;
-  CBS in, content_info, content_type, wrapped_signed_data, signed_data,
-      certificates;
-  const size_t initial_certs_len = sk_X509_num(out_certs);
+  CBS in, content_info, content_type, wrapped_signed_data, signed_data;
   uint64_t version;
-  int ret = 0;
 
   /* The input may be in BER format. */
-  if (!CBS_asn1_ber_to_der(cbs, &der_bytes, &der_len)) {
+  *der_bytes = NULL;
+  if (!CBS_asn1_ber_to_der(cbs, der_bytes, &der_len)) {
     return 0;
   }
-  if (der_bytes != NULL) {
-    CBS_init(&in, der_bytes, der_len);
+  if (*der_bytes != NULL) {
+    CBS_init(&in, *der_bytes, der_len);
   } else {
     CBS_init(&in, CBS_data(cbs), CBS_len(cbs));
   }
@@ -48,7 +55,7 @@ int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
   }
 
   if (OBJ_cbs2nid(&content_type) != NID_pkcs7_signed) {
-    OPENSSL_PUT_ERROR(X509, PKCS7_get_certificates,
+    OPENSSL_PUT_ERROR(X509, pkcs7_parse_header,
                       X509_R_NOT_PKCS7_SIGNED_DATA);
     goto err;
   }
@@ -64,11 +71,34 @@ int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
   }
 
   if (version < 1) {
-    OPENSSL_PUT_ERROR(X509, PKCS7_get_certificates,
+    OPENSSL_PUT_ERROR(X509, pkcs7_parse_header,
                       X509_R_BAD_PKCS7_VERSION);
     goto err;
   }
 
+  CBS_init(out, CBS_data(&signed_data), CBS_len(&signed_data));
+  return 1;
+
+err:
+  if (*der_bytes) {
+    OPENSSL_free(*der_bytes);
+    *der_bytes = NULL;
+  }
+
+  return 0;
+}
+
+int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
+  CBS signed_data, certificates;
+  uint8_t *der_bytes = NULL;
+  int ret = 0;
+  const size_t initial_certs_len = sk_X509_num(out_certs);
+
+  if (!pkcs7_parse_header(&der_bytes, &signed_data, cbs)) {
+    return 0;
+  }
+
+  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
   if (!CBS_get_asn1(&signed_data, &certificates,
                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
     OPENSSL_PUT_ERROR(X509, PKCS7_get_certificates,
@@ -91,12 +121,12 @@ int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
       goto err;
     }
 
-    if (inp != CBS_data(&cert) + CBS_len(&cert)) {
-      /* This suggests a disconnect between the two ASN.1 parsers. */
+    assert(inp == CBS_data(&cert) + CBS_len(&cert));
+
+    if (sk_X509_push(out_certs, x509) == 0) {
+      X509_free(x509);
       goto err;
     }
-
-    sk_X509_push(out_certs, x509);
   }
 
   ret = 1;
@@ -116,10 +146,83 @@ err:
   return ret;
 }
 
-int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
+int PKCS7_get_CRLs(STACK_OF(X509_CRL) *out_crls, CBS *cbs) {
+  CBS signed_data, crls;
+  uint8_t *der_bytes = NULL;
+  int ret = 0;
+  const size_t initial_crls_len = sk_X509_CRL_num(out_crls);
+
+  if (!pkcs7_parse_header(&der_bytes, &signed_data, cbs)) {
+    return 0;
+  }
+
+  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
+
+  /* Even if only CRLs are included, there may be an empty certificates block.
+   * OpenSSL does this, for example. */
+  if (CBS_peek_asn1_tag(&signed_data,
+                        CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) &&
+      !CBS_get_asn1(&signed_data, NULL /* certificates */,
+                    CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
+    goto err;
+  }
+
+  if (!CBS_get_asn1(&signed_data, &crls,
+                    CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1)) {
+    OPENSSL_PUT_ERROR(X509, PKCS7_get_CRLs,
+                      X509_R_NO_CRLS_INCLUDED);
+    goto err;
+  }
+
+  while (CBS_len(&crls) > 0) {
+    CBS crl_data;
+    X509_CRL *crl;
+    const uint8_t *inp;
+
+    if (!CBS_get_asn1_element(&crls, &crl_data, CBS_ASN1_SEQUENCE)) {
+      goto err;
+    }
+
+    inp = CBS_data(&crl_data);
+    crl = d2i_X509_CRL(NULL, &inp, CBS_len(&crl_data));
+    if (!crl) {
+      goto err;
+    }
+
+    assert(inp == CBS_data(&crl_data) + CBS_len(&crl_data));
+
+    if (sk_X509_CRL_push(out_crls, crl) == 0) {
+      X509_CRL_free(crl);
+      goto err;
+    }
+  }
+
+  ret = 1;
+
+err:
+  if (der_bytes) {
+    OPENSSL_free(der_bytes);
+  }
+
+  if (!ret) {
+    while (sk_X509_CRL_num(out_crls) != initial_crls_len) {
+      X509_CRL_free(sk_X509_CRL_pop(out_crls));
+    }
+  }
+
+  return ret;
+}
+
+/* pkcs7_bundle writes a PKCS#7, SignedData structure to |out| and then calls
+ * |cb| with a CBB to which certificate or CRL data can be written, and the
+ * opaque context pointer, |arg|. The callback can return zero to indicate an
+ * error.
+ *
+ * pkcs7_bundle returns one on success or zero on error. */
+static int pkcs7_bundle(CBB *out, int (*cb)(CBB *out, const void *arg),
+                        const void *arg) {
   CBB outer_seq, wrapped_seq, seq, version_bytes, digest_algos_set,
-      content_info, certificates;
-  size_t i;
+      content_info;
 
   /* See https://tools.ietf.org/html/rfc2315#section-7 */
   if (!CBB_add_asn1(out, &outer_seq, CBS_ASN1_SEQUENCE) ||
@@ -133,7 +236,20 @@ int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
       !CBB_add_asn1(&seq, &digest_algos_set, CBS_ASN1_SET) ||
       !CBB_add_asn1(&seq, &content_info, CBS_ASN1_SEQUENCE) ||
       !OBJ_nid2cbb(&content_info, NID_pkcs7_data) ||
-      !CBB_add_asn1(&seq, &certificates,
+      !cb(&seq, arg)) {
+    return 0;
+  }
+
+  return CBB_flush(out);
+}
+
+static int pkcs7_bundle_certificates_cb(CBB *out, const void *arg) {
+  const STACK_OF(X509) *certs = arg;
+  size_t i;
+  CBB certificates;
+
+  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
+  if (!CBB_add_asn1(out, &certificates,
                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
     return 0;
   }
@@ -152,3 +268,37 @@ int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
 
   return CBB_flush(out);
 }
+
+int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
+  return pkcs7_bundle(out, pkcs7_bundle_certificates_cb, certs);
+}
+
+static int pkcs7_bundle_crls_cb(CBB *out, const void *arg) {
+  const STACK_OF(X509_CRL) *crls = arg;
+  size_t i;
+  CBB crl_data;
+
+  /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
+  if (!CBB_add_asn1(out, &crl_data,
+                    CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1)) {
+    return 0;
+  }
+
+  for (i = 0; i < sk_X509_CRL_num(crls); i++) {
+    X509_CRL *crl = sk_X509_CRL_value(crls, i);
+    uint8_t *buf;
+    int len = i2d_X509_CRL(crl, NULL);
+
+    if (len < 0 ||
+        !CBB_add_space(&crl_data, &buf, len) ||
+        i2d_X509_CRL(crl, &buf) < 0) {
+      return 0;
+    }
+  }
+
+  return CBB_flush(out);
+}
+
+int PKCS7_bundle_CRLs(CBB *out, const STACK_OF(X509_CRL) *crls) {
+  return pkcs7_bundle(out, pkcs7_bundle_crls_cb, crls);
+}
diff --git a/src/crypto/x509/pkcs7_test.c b/src/crypto/x509/pkcs7_test.c
index 4283022..ff61a2b 100644
--- a/src/crypto/x509/pkcs7_test.c
+++ b/src/crypto/x509/pkcs7_test.c
@@ -331,7 +331,88 @@ static const uint8_t kPKCS7Windows[] = {
     0xcd, 0x5a, 0x2a, 0x82, 0xb2, 0x37, 0x79, 0x31, 0x00,
 };
 
-static int test_reparse(const uint8_t *der_bytes, size_t der_len) {
+/* kOpenSSLCRL is the Equifax CRL, converted to PKCS#7 form by:
+ *   openssl crl2pkcs7 -inform DER -in secureca.crl  */
+static const uint8_t kOpenSSLCRL[] = {
+    0x30, 0x82, 0x03, 0x85, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d,
+    0x01, 0x07, 0x02, 0xa0, 0x82, 0x03, 0x76, 0x30, 0x82, 0x03, 0x72, 0x02,
+    0x01, 0x01, 0x31, 0x00, 0x30, 0x0b, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
+    0xf7, 0x0d, 0x01, 0x07, 0x01, 0xa0, 0x00, 0xa1, 0x82, 0x03, 0x58, 0x30,
+    0x82, 0x03, 0x54, 0x30, 0x82, 0x02, 0xbd, 0x30, 0x0d, 0x06, 0x09, 0x2a,
+    0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x05, 0x05, 0x00, 0x30, 0x4e,
+    0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x55,
+    0x53, 0x31, 0x10, 0x30, 0x0e, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x13, 0x07,
+    0x45, 0x71, 0x75, 0x69, 0x66, 0x61, 0x78, 0x31, 0x2d, 0x30, 0x2b, 0x06,
+    0x03, 0x55, 0x04, 0x0b, 0x13, 0x24, 0x45, 0x71, 0x75, 0x69, 0x66, 0x61,
+    0x78, 0x20, 0x53, 0x65, 0x63, 0x75, 0x72, 0x65, 0x20, 0x43, 0x65, 0x72,
+    0x74, 0x69, 0x66, 0x69, 0x63, 0x61, 0x74, 0x65, 0x20, 0x41, 0x75, 0x74,
+    0x68, 0x6f, 0x72, 0x69, 0x74, 0x79, 0x17, 0x0d, 0x31, 0x35, 0x30, 0x32,
+    0x32, 0x37, 0x30, 0x31, 0x32, 0x33, 0x30, 0x30, 0x5a, 0x17, 0x0d, 0x31,
+    0x35, 0x30, 0x33, 0x30, 0x39, 0x30, 0x31, 0x32, 0x33, 0x30, 0x30, 0x5a,
+    0x30, 0x82, 0x02, 0x3c, 0x30, 0x14, 0x02, 0x03, 0x0f, 0x58, 0xe4, 0x17,
+    0x0d, 0x31, 0x34, 0x30, 0x34, 0x32, 0x37, 0x30, 0x38, 0x31, 0x39, 0x32,
+    0x32, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x14, 0x76, 0x19, 0x17, 0x0d, 0x31,
+    0x34, 0x30, 0x36, 0x31, 0x38, 0x31, 0x35, 0x30, 0x30, 0x30, 0x33, 0x5a,
+    0x30, 0x14, 0x02, 0x03, 0x0f, 0x9a, 0xfb, 0x17, 0x0d, 0x31, 0x34, 0x30,
+    0x34, 0x32, 0x39, 0x31, 0x38, 0x30, 0x39, 0x31, 0x37, 0x5a, 0x30, 0x14,
+    0x02, 0x03, 0x14, 0x8b, 0xc0, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x37, 0x30,
+    0x39, 0x31, 0x39, 0x34, 0x36, 0x33, 0x33, 0x5a, 0x30, 0x14, 0x02, 0x03,
+    0x14, 0xe4, 0x9c, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x34, 0x31, 0x36, 0x32,
+    0x33, 0x33, 0x39, 0x33, 0x35, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x0f, 0x86,
+    0x07, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x35, 0x32, 0x31, 0x31, 0x35, 0x35,
+    0x30, 0x35, 0x33, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x12, 0xe2, 0x29, 0x17,
+    0x0d, 0x31, 0x34, 0x30, 0x36, 0x31, 0x37, 0x31, 0x38, 0x35, 0x35, 0x31,
+    0x35, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x0d, 0x42, 0x66, 0x17, 0x0d, 0x31,
+    0x32, 0x30, 0x36, 0x32, 0x37, 0x31, 0x37, 0x31, 0x30, 0x35, 0x33, 0x5a,
+    0x30, 0x14, 0x02, 0x03, 0x03, 0x1e, 0x33, 0x17, 0x0d, 0x30, 0x32, 0x30,
+    0x35, 0x31, 0x35, 0x31, 0x33, 0x30, 0x36, 0x31, 0x31, 0x5a, 0x30, 0x14,
+    0x02, 0x03, 0x12, 0xe2, 0x23, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x36, 0x30,
+    0x36, 0x32, 0x30, 0x34, 0x30, 0x32, 0x31, 0x5a, 0x30, 0x14, 0x02, 0x03,
+    0x13, 0x9c, 0xab, 0x17, 0x0d, 0x31, 0x30, 0x30, 0x37, 0x32, 0x39, 0x31,
+    0x36, 0x34, 0x34, 0x33, 0x39, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x12, 0xc6,
+    0x0a, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x36, 0x30, 0x36, 0x32, 0x32, 0x32,
+    0x31, 0x33, 0x39, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x03, 0x25, 0x85, 0x17,
+    0x0d, 0x30, 0x32, 0x30, 0x35, 0x31, 0x34, 0x31, 0x38, 0x31, 0x31, 0x35,
+    0x37, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x14, 0x86, 0xe6, 0x17, 0x0d, 0x31,
+    0x34, 0x30, 0x37, 0x32, 0x35, 0x30, 0x32, 0x30, 0x30, 0x33, 0x38, 0x5a,
+    0x30, 0x14, 0x02, 0x03, 0x13, 0x9c, 0xa1, 0x17, 0x0d, 0x31, 0x30, 0x30,
+    0x37, 0x32, 0x39, 0x31, 0x36, 0x34, 0x37, 0x33, 0x32, 0x5a, 0x30, 0x14,
+    0x02, 0x03, 0x15, 0x4d, 0x5c, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x34, 0x33,
+    0x30, 0x30, 0x30, 0x30, 0x34, 0x34, 0x32, 0x5a, 0x30, 0x14, 0x02, 0x03,
+    0x0f, 0xfa, 0x2d, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x36, 0x31, 0x37, 0x31,
+    0x38, 0x35, 0x30, 0x31, 0x31, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x13, 0x75,
+    0x55, 0x17, 0x0d, 0x31, 0x35, 0x30, 0x31, 0x31, 0x38, 0x30, 0x32, 0x32,
+    0x31, 0x33, 0x33, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x0f, 0x56, 0x96, 0x17,
+    0x0d, 0x31, 0x34, 0x30, 0x36, 0x32, 0x34, 0x31, 0x32, 0x33, 0x31, 0x30,
+    0x32, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x0b, 0x80, 0x8a, 0x17, 0x0d, 0x31,
+    0x32, 0x30, 0x36, 0x32, 0x37, 0x31, 0x37, 0x31, 0x30, 0x32, 0x35, 0x5a,
+    0x30, 0x14, 0x02, 0x03, 0x0f, 0x94, 0x16, 0x17, 0x0d, 0x31, 0x30, 0x30,
+    0x33, 0x30, 0x31, 0x31, 0x33, 0x34, 0x35, 0x33, 0x31, 0x5a, 0x30, 0x14,
+    0x02, 0x03, 0x14, 0x16, 0xb3, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x36, 0x31,
+    0x38, 0x31, 0x34, 0x33, 0x32, 0x35, 0x36, 0x5a, 0x30, 0x14, 0x02, 0x03,
+    0x0a, 0xe1, 0x85, 0x17, 0x0d, 0x31, 0x32, 0x30, 0x36, 0x32, 0x37, 0x31,
+    0x37, 0x31, 0x30, 0x31, 0x37, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x14, 0xcc,
+    0x3e, 0x17, 0x0d, 0x31, 0x34, 0x30, 0x37, 0x31, 0x31, 0x31, 0x32, 0x35,
+    0x35, 0x33, 0x31, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x10, 0x5b, 0xcb, 0x17,
+    0x0d, 0x31, 0x30, 0x30, 0x37, 0x33, 0x30, 0x32, 0x31, 0x33, 0x31, 0x32,
+    0x30, 0x5a, 0x30, 0x14, 0x02, 0x03, 0x15, 0x6a, 0x1f, 0x17, 0x0d, 0x31,
+    0x34, 0x30, 0x32, 0x32, 0x36, 0x31, 0x32, 0x33, 0x35, 0x31, 0x39, 0x5a,
+    0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
+    0x05, 0x05, 0x00, 0x03, 0x81, 0x81, 0x00, 0x1d, 0x5c, 0x27, 0x07, 0x11,
+    0x03, 0xf2, 0x00, 0xbd, 0xf4, 0x46, 0x3e, 0x71, 0xfd, 0x10, 0x84, 0x83,
+    0xd9, 0xd2, 0xd2, 0x19, 0xa0, 0x20, 0xf7, 0x1a, 0x43, 0x3d, 0xac, 0xda,
+    0x33, 0xfc, 0xb7, 0x42, 0x60, 0x1a, 0xa4, 0xa8, 0xb2, 0x07, 0x5c, 0x51,
+    0x16, 0xc0, 0x42, 0x80, 0x0a, 0x0f, 0xf0, 0x47, 0x5b, 0x4b, 0x78, 0x90,
+    0xaf, 0xc7, 0xac, 0x48, 0xf8, 0xca, 0x3c, 0x13, 0x5e, 0xf6, 0xd1, 0x88,
+    0xae, 0x55, 0xa3, 0x0c, 0x8a, 0x62, 0x47, 0x29, 0xf8, 0x72, 0xb8, 0x24,
+    0x17, 0xaf, 0xb2, 0x06, 0x1e, 0xa7, 0x72, 0x76, 0xab, 0x96, 0x1d, 0xe0,
+    0x7c, 0xd4, 0x0c, 0x42, 0x82, 0x3d, 0x4a, 0x8e, 0x15, 0x77, 0x2f, 0x3c,
+    0x2a, 0x8c, 0x3a, 0x04, 0x10, 0x55, 0xdc, 0xbb, 0xba, 0xb1, 0x91, 0xee,
+    0x7b, 0xe7, 0x23, 0xc5, 0x71, 0x13, 0xae, 0x6b, 0x21, 0x35, 0xd3, 0x64,
+    0xf0, 0x00, 0x54, 0x31, 0x00,
+};
+
+static int test_cert_reparse(const uint8_t *der_bytes, size_t der_len) {
   CBS pkcs7;
   CBB cbb;
   STACK_OF(X509) *certs = sk_X509_new_null();
@@ -395,11 +476,76 @@ static int test_reparse(const uint8_t *der_bytes, size_t der_len) {
   return 1;
 }
 
+static int test_crl_reparse(const uint8_t *der_bytes, size_t der_len) {
+  CBS pkcs7;
+  CBB cbb;
+  STACK_OF(X509_CRL) *crls = sk_X509_CRL_new_null();
+  STACK_OF(X509_CRL) *crls2 = sk_X509_CRL_new_null();
+  uint8_t *result_data, *result2_data;
+  size_t result_len, result2_len, i;
+
+  CBS_init(&pkcs7, der_bytes, der_len);
+  if (!PKCS7_get_CRLs(crls, &pkcs7)) {
+    fprintf(stderr, "PKCS7_get_CRLs failed.\n");
+    return 0;
+  }
+
+  CBB_init(&cbb, der_len);
+  if (!PKCS7_bundle_CRLs(&cbb, crls) ||
+      !CBB_finish(&cbb, &result_data, &result_len)) {
+    fprintf(stderr, "PKCS7_bundle_CRLs failed.\n");
+    return 0;
+  }
+
+  CBS_init(&pkcs7, result_data, result_len);
+  if (!PKCS7_get_CRLs(crls2, &pkcs7)) {
+    fprintf(stderr, "PKCS7_get_CRLs reparse failed.\n");
+    return 0;
+  }
+
+  if (sk_X509_CRL_num(crls) != sk_X509_CRL_num(crls)) {
+    fprintf(stderr, "Number of CRLs in results differ.\n");
+    return 0;
+  }
+
+  for (i = 0; i < sk_X509_CRL_num(crls); i++) {
+    X509_CRL *a = sk_X509_CRL_value(crls, i);
+    X509_CRL *b = sk_X509_CRL_value(crls2, i);
+
+    if (X509_CRL_cmp(a, b) != 0) {
+      fprintf(stderr, "CRL %u differs.\n", (unsigned) i);
+      return 0;
+    }
+  }
+
+  CBB_init(&cbb, der_len);
+  if (!PKCS7_bundle_CRLs(&cbb, crls2) ||
+      !CBB_finish(&cbb, &result2_data, &result2_len)) {
+    fprintf(stderr,
+            "PKCS7_bundle_CRLs failed the second time.\n");
+    return 0;
+  }
+
+  if (result_len != result2_len ||
+      memcmp(result_data, result2_data, result_len) != 0) {
+    fprintf(stderr, "Serialisation is not stable.\n");
+    return 0;
+  }
+
+  OPENSSL_free(result_data);
+  OPENSSL_free(result2_data);
+  sk_X509_CRL_pop_free(crls, X509_CRL_free);
+  sk_X509_CRL_pop_free(crls2, X509_CRL_free);
+
+  return 1;
+}
+
 int main(void) {
   CRYPTO_library_init();
 
-  if (!test_reparse(kPKCS7NSS, sizeof(kPKCS7NSS)) ||
-      !test_reparse(kPKCS7Windows, sizeof(kPKCS7Windows))) {
+  if (!test_cert_reparse(kPKCS7NSS, sizeof(kPKCS7NSS)) ||
+      !test_cert_reparse(kPKCS7Windows, sizeof(kPKCS7Windows)) ||
+      !test_crl_reparse(kOpenSSLCRL, sizeof(kOpenSSLCRL))) {
     return 1;
   }
 
diff --git a/src/crypto/x509/x509_error.c b/src/crypto/x509/x509_error.c
index 222a40a..6669a7a 100644
--- a/src/crypto/x509/x509_error.c
+++ b/src/crypto/x509/x509_error.c
@@ -24,6 +24,7 @@ const ERR_STRING_DATA X509_error_string_data[] = {
   {ERR_PACK(ERR_LIB_X509, X509_F_ASN1_sign, 0), "ASN1_sign"},
   {ERR_PACK(ERR_LIB_X509, X509_F_NETSCAPE_SPKI_b64_decode, 0), "NETSCAPE_SPKI_b64_decode"},
   {ERR_PACK(ERR_LIB_X509, X509_F_NETSCAPE_SPKI_b64_encode, 0), "NETSCAPE_SPKI_b64_encode"},
+  {ERR_PACK(ERR_LIB_X509, X509_F_PKCS7_get_CRLs, 0), "PKCS7_get_CRLs"},
   {ERR_PACK(ERR_LIB_X509, X509_F_PKCS7_get_certificates, 0), "PKCS7_get_certificates"},
   {ERR_PACK(ERR_LIB_X509, X509_F_X509_ATTRIBUTE_create_by_NID, 0), "X509_ATTRIBUTE_create_by_NID"},
   {ERR_PACK(ERR_LIB_X509, X509_F_X509_ATTRIBUTE_create_by_OBJ, 0), "X509_ATTRIBUTE_create_by_OBJ"},
@@ -80,6 +81,7 @@ const ERR_STRING_DATA X509_error_string_data[] = {
   {ERR_PACK(ERR_LIB_X509, X509_F_i2d_PrivateKey, 0), "i2d_PrivateKey"},
   {ERR_PACK(ERR_LIB_X509, X509_F_i2d_RSA_PUBKEY, 0), "i2d_RSA_PUBKEY"},
   {ERR_PACK(ERR_LIB_X509, X509_F_parse_tagging, 0), "parse_tagging"},
+  {ERR_PACK(ERR_LIB_X509, X509_F_pkcs7_parse_header, 0), "pkcs7_parse_header"},
   {ERR_PACK(ERR_LIB_X509, X509_F_x509_name_encode, 0), "x509_name_encode"},
   {ERR_PACK(ERR_LIB_X509, X509_F_x509_name_ex_d2i, 0), "x509_name_ex_d2i"},
   {ERR_PACK(ERR_LIB_X509, X509_F_x509_name_ex_new, 0), "x509_name_ex_new"},
@@ -108,6 +110,7 @@ const ERR_STRING_DATA X509_error_string_data[] = {
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_NOT_PKCS7_SIGNED_DATA), "NOT_PKCS7_SIGNED_DATA"},
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_NO_CERTIFICATES_INCLUDED), "NO_CERTIFICATES_INCLUDED"},
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_NO_CERT_SET_FOR_US_TO_VERIFY), "NO_CERT_SET_FOR_US_TO_VERIFY"},
+  {ERR_PACK(ERR_LIB_X509, 0, X509_R_NO_CRLS_INCLUDED), "NO_CRLS_INCLUDED"},
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_NO_CRL_NUMBER), "NO_CRL_NUMBER"},
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_PUBLIC_KEY_DECODE_ERROR), "PUBLIC_KEY_DECODE_ERROR"},
   {ERR_PACK(ERR_LIB_X509, 0, X509_R_PUBLIC_KEY_ENCODE_ERROR), "PUBLIC_KEY_ENCODE_ERROR"},
diff --git a/src/include/openssl/x509.h b/src/include/openssl/x509.h
index 1ee63a1..987c353 100644
--- a/src/include/openssl/x509.h
+++ b/src/include/openssl/x509.h
@@ -1165,10 +1165,19 @@ OPENSSL_EXPORT int X509_TRUST_get_trust(X509_TRUST *xp);
 OPENSSL_EXPORT int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs);
 
 /* PKCS7_bundle_certificates appends a PKCS#7, SignedData structure containing
- * |certs| to |cbb|. It returns one on success and zero on error. */
+ * |certs| to |out|. It returns one on success and zero on error. */
 OPENSSL_EXPORT int PKCS7_bundle_certificates(
     CBB *out, const STACK_OF(X509) *certs);
 
+/* PKCS7_get_CRLs parses a PKCS#7, SignedData structure from |cbs| and appends
+ * the included CRLs to |out_crls|. It returns one on success and zero on
+ * error. */
+OPENSSL_EXPORT int PKCS7_get_CRLs(STACK_OF(X509_CRL) *out_crls, CBS *cbs);
+
+/* PKCS7_bundle_CRLs appends a PKCS#7, SignedData structure containing
+ * |crls| to |out|. It returns one on success and zero on error. */
+OPENSSL_EXPORT int PKCS7_bundle_CRLs(CBB *out, const STACK_OF(X509_CRL) *crls);
+
 
 /* EVP_PK values indicate the algorithm of the public key in a certificate. */
 
@@ -1267,6 +1276,8 @@ OPENSSL_EXPORT int PKCS7_bundle_certificates(
 #define X509_F_i2d_DSA_PUBKEY 163
 #define X509_F_X509_TRUST_add 164
 #define X509_F_X509_NAME_ENTRY_create_by_NID 165
+#define X509_F_PKCS7_get_CRLs 166
+#define X509_F_pkcs7_parse_header 167
 #define X509_R_NO_CERT_SET_FOR_US_TO_VERIFY 100
 #define X509_R_UNABLE_TO_FIND_PARAMETERS_IN_CHAIN 101
 #define X509_R_METHOD_NOT_SUPPORTED 102
@@ -1305,5 +1316,6 @@ OPENSSL_EXPORT int PKCS7_bundle_certificates(
 #define X509_R_ERR_ASN1_LIB 136
 #define X509_R_AKID_MISMATCH 137
 #define X509_R_INVALID_BIT_STRING_BITS_LEFT 138
+#define X509_R_NO_CRLS_INCLUDED 139
 
 #endif