scripts/sign-file.c: Add support for signing with a raw signature

This patch adds support for signing a kernel module with a raw
detached PKCS#7 signature/message.

The signature is not converted and is simply appended to the module so
it needs to be in the right format. Using openssl, a valid signature can
be generated like this:
  $ openssl smime -sign -nocerts -noattr -binary -in <module> -inkey \
    <key> -signer <x509> -outform der -out <raw sig>

The resulting raw signature from the above command is (more or less)
identical to the raw signature that sign-file itself can produce like
this:
  $ scripts/sign-file -d <hash algo> <key> <x509> <module>

Signed-off-by: Juerg Haefliger <juerg.haefliger@hpe.com>
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 146 insertions, 90 deletions

diff --git a/scripts/sign-file.c b/scripts/sign-file.c
index a0b806d2b31d..80b7f7f933d6 100755
--- a/scripts/sign-file.c
+++ b/scripts/sign-file.c
@@ -2,9 +2,11 @@
  *
  * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved.
  * Copyright © 2015      Intel Corporation.
+ * Copyright © 2016      Hewlett Packard Enterprise Development LP
  *
  * Authors: David Howells <dhowells@redhat.com>
  *          David Woodhouse <dwmw2@infradead.org>
+ *          Juerg Haefliger <juerg.haefliger@hpe.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -67,6 +69,8 @@ void format(void)
 {
         fprintf(stderr,
                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
+        fprintf(stderr,
+                "       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
         exit(2);
 }
 
@@ -126,26 +130,84 @@ static int pem_pw_cb(char *buf, int len, int w, void *v)
         return pwlen;
 }
 
+static EVP_PKEY *read_private_key(const char *private_key_name)
+{
+        EVP_PKEY *private_key;
+
+        if (!strncmp(private_key_name, "pkcs11:", 7)) {
+                ENGINE *e;
+
+                ENGINE_load_builtin_engines();
+                drain_openssl_errors();
+                e = ENGINE_by_id("pkcs11");
+                ERR(!e, "Load PKCS#11 ENGINE");
+                if (ENGINE_init(e))
+                        drain_openssl_errors();
+                else
+                        ERR(1, "ENGINE_init");
+                if (key_pass)
+                        ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
+                            "Set PKCS#11 PIN");
+                private_key = ENGINE_load_private_key(e, private_key_name,
+                                                      NULL, NULL);
+                ERR(!private_key, "%s", private_key_name);
+        } else {
+                BIO *b;
+
+                b = BIO_new_file(private_key_name, "rb");
+                ERR(!b, "%s", private_key_name);
+                private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
+                                                      NULL);
+                ERR(!private_key, "%s", private_key_name);
+                BIO_free(b);
+        }
+
+        return private_key;
+}
+
+static X509 *read_x509(const char *x509_name)
+{
+        X509 *x509;
+        BIO *b;
+
+        b = BIO_new_file(x509_name, "rb");
+        ERR(!b, "%s", x509_name);
+        x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
+        if (!x509) {
+                ERR(BIO_reset(b) != 1, "%s", x509_name);
+                x509 = PEM_read_bio_X509(b, NULL, NULL,
+                                         NULL); /* PEM encoded X.509 */
+                if (x509)
+                        drain_openssl_errors();
+        }
+        BIO_free(b);
+        ERR(!x509, "%s", x509_name);
+
+        return x509;
+}
+
 int main(int argc, char **argv)
 {
         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
         char *hash_algo = NULL;
-        char *private_key_name, *x509_name, *module_name, *dest_name;
+        char *private_key_name = NULL, *raw_sig_name = NULL;
+        char *x509_name, *module_name, *dest_name;
         bool save_sig = false, replace_orig;
         bool sign_only = false;
+        bool raw_sig = false;
         unsigned char buf[4096];
         unsigned long module_size, sig_size;
         unsigned int use_signed_attrs;
         const EVP_MD *digest_algo;
         EVP_PKEY *private_key;
 #ifndef USE_PKCS7
-        CMS_ContentInfo *cms;
+        CMS_ContentInfo *cms = NULL;
         unsigned int use_keyid = 0;
 #else
-        PKCS7 *pkcs7;
+        PKCS7 *pkcs7 = NULL;
 #endif
         X509 *x509;
-        BIO *b, *bd = NULL, *bm;
+        BIO *bd, *bm;
         int opt, n;
         OpenSSL_add_all_algorithms();
         ERR_load_crypto_strings();
@@ -160,8 +222,9 @@ int main(int argc, char **argv)
 #endif
 
         do {
-                opt = getopt(argc, argv, "dpk");
+                opt = getopt(argc, argv, "sdpk");
                 switch (opt) {
+                case 's': raw_sig = true; break;
                 case 'p': save_sig = true; break;
                 case 'd': sign_only = true; save_sig = true; break;
 #ifndef USE_PKCS7
@@ -177,8 +240,13 @@ int main(int argc, char **argv)
         if (argc < 4 || argc > 5)
                 format();
 
-        hash_algo = argv[0];
-        private_key_name = argv[1];
+        if (raw_sig) {
+                raw_sig_name = argv[0];
+                hash_algo = argv[1];
+        } else {
+                hash_algo = argv[0];
+                private_key_name = argv[1];
+        }
         x509_name = argv[2];
         module_name = argv[3];
         if (argc == 5) {
@@ -198,101 +266,74 @@ int main(int argc, char **argv)
         }
 #endif
 
-        /* Read the private key and the X.509 cert the PKCS#7 message
-         * will point to.
-         */
-        if (!strncmp(private_key_name, "pkcs11:", 7)) {
-                ENGINE *e;
-
-                ENGINE_load_builtin_engines();
-                drain_openssl_errors();
-                e = ENGINE_by_id("pkcs11");
-                ERR(!e, "Load PKCS#11 ENGINE");
-                if (ENGINE_init(e))
-                        drain_openssl_errors();
-                else
-                        ERR(1, "ENGINE_init");
-                if (key_pass)
-                        ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
-                private_key = ENGINE_load_private_key(e, private_key_name, NULL,
-                                                      NULL);
-                ERR(!private_key, "%s", private_key_name);
-        } else {
-                b = BIO_new_file(private_key_name, "rb");
-                ERR(!b, "%s", private_key_name);
-                private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb, NULL);
-                ERR(!private_key, "%s", private_key_name);
-                BIO_free(b);
-        }
-
-        b = BIO_new_file(x509_name, "rb");
-        ERR(!b, "%s", x509_name);
-        x509 = d2i_X509_bio(b, NULL); /* Binary encoded X.509 */
-        if (!x509) {
-                ERR(BIO_reset(b) != 1, "%s", x509_name);
-                x509 = PEM_read_bio_X509(b, NULL, NULL, NULL); /* PEM encoded X.509 */
-                if (x509)
-                        drain_openssl_errors();
-        }
-        BIO_free(b);
-        ERR(!x509, "%s", x509_name);
-
-        /* Open the destination file now so that we can shovel the module data
-         * across as we read it.
-         */
-        if (!sign_only) {
-                bd = BIO_new_file(dest_name, "wb");
-                ERR(!bd, "%s", dest_name);
-        }
-
-        /* Digest the module data. */
-        OpenSSL_add_all_digests();
-        display_openssl_errors(__LINE__);
-        digest_algo = EVP_get_digestbyname(hash_algo);
-        ERR(!digest_algo, "EVP_get_digestbyname");
-
+        /* Open the module file */
         bm = BIO_new_file(module_name, "rb");
         ERR(!bm, "%s", module_name);
 
+        if (!raw_sig) {
+                /* Read the private key and the X.509 cert the PKCS#7 message
+                 * will point to.
+                 */
+                private_key = read_private_key(private_key_name);
+                x509 = read_x509(x509_name);
+
+                /* Digest the module data. */
+                OpenSSL_add_all_digests();
+                display_openssl_errors(__LINE__);
+                digest_algo = EVP_get_digestbyname(hash_algo);
+                ERR(!digest_algo, "EVP_get_digestbyname");
+
 #ifndef USE_PKCS7
-        /* Load the signature message from the digest buffer. */
-        cms = CMS_sign(NULL, NULL, NULL, NULL,
-                       CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | CMS_STREAM);
-        ERR(!cms, "CMS_sign");
-
-        ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
-                             CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP |
-                             use_keyid | use_signed_attrs),
-            "CMS_add1_signer");
-        ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
-            "CMS_final");
+                /* Load the signature message from the digest buffer. */
+                cms = CMS_sign(NULL, NULL, NULL, NULL,
+                               CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
+                               CMS_DETACHED | CMS_STREAM);
+                ERR(!cms, "CMS_sign");
+
+                ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
+                                     CMS_NOCERTS | CMS_BINARY |
+                                     CMS_NOSMIMECAP | use_keyid |
+                                     use_signed_attrs),
+                    "CMS_add1_signer");
+                ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
+                    "CMS_final");
 
 #else
-        pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
-                           PKCS7_NOCERTS | PKCS7_BINARY |
-                           PKCS7_DETACHED | use_signed_attrs);
-        ERR(!pkcs7, "PKCS7_sign");
+                pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
+                                   PKCS7_NOCERTS | PKCS7_BINARY |
+                                   PKCS7_DETACHED | use_signed_attrs);
+                ERR(!pkcs7, "PKCS7_sign");
 #endif
 
-        if (save_sig) {
-                char *sig_file_name;
+                if (save_sig) {
+                        char *sig_file_name;
+                        BIO *b;
 
-                ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
-                    "asprintf");
-                b = BIO_new_file(sig_file_name, "wb");
-                ERR(!b, "%s", sig_file_name);
+                        ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
+                            "asprintf");
+                        b = BIO_new_file(sig_file_name, "wb");
+                        ERR(!b, "%s", sig_file_name);
 #ifndef USE_PKCS7
-                ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
-                    "%s", sig_file_name);
+                        ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
+                            "%s", sig_file_name);
 #else
-                ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
-                        "%s", sig_file_name);
+                        ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
+                            "%s", sig_file_name);
 #endif
-                BIO_free(b);
+                        BIO_free(b);
+                }
+
+                if (sign_only) {
+                        BIO_free(bm);
+                        return 0;
+                }
         }
 
-        if (sign_only)
-                return 0;
+        /* Open the destination file now so that we can shovel the module data
+         * across as we read it.
+         */
+        bd = BIO_new_file(dest_name, "wb");
+        ERR(!bd, "%s", dest_name);
 
         /* Append the marker and the PKCS#7 message to the destination file */
         ERR(BIO_reset(bm) < 0, "%s", module_name);
@@ -300,14 +341,29 @@ int main(int argc, char **argv)
                n > 0) {
                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
         }
+        BIO_free(bm);
         ERR(n < 0, "%s", module_name);
         module_size = BIO_number_written(bd);
 
+        if (!raw_sig) {
 #ifndef USE_PKCS7
-        ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
+                ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
 #else
-        ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
+                ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
 #endif
+        } else {
+                BIO *b;
+
+                /* Read the raw signature file and write the data to the
+                 * destination file
+                 */
+                b = BIO_new_file(raw_sig_name, "rb");
+                ERR(!b, "%s", raw_sig_name);
+                while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
+                        ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
+                BIO_free(b);
+        }
+
         sig_size = BIO_number_written(bd) - module_size;
         sig_info.sig_len = htonl(sig_size);
         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);