extract-cert: Cope with multiple X.509 certificates in a single file

This is not required for the module signing key, although it doesn't do any
harm — it just means that any additional certs in the PEM file are also
trusted by the kernel.

But it does allow us to use the extract-cert tool for processing the extra
certs from CONFIG_SYSTEM_TRUSTED_KEYS, instead of that horrid awk|base64
hack.

Also cope with being invoked with no input file, creating an empty output
file as a result.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 46 insertions, 12 deletions

diff --git a/scripts/extract-cert.c b/scripts/extract-cert.c
index 4fd5b2f07b45..fd0db015c65c 100644
--- a/scripts/extract-cert.c
+++ b/scripts/extract-cert.c
@@ -73,17 +73,34 @@ static void drain_openssl_errors(void)
         } while(0)
 
 static const char *key_pass;
+static BIO *wb;
+static char *cert_dst;
+int kbuild_verbose;
+
+static void write_cert(X509 *x509)
+{
+        char buf[200];
+
+        if (!wb) {
+                wb = BIO_new_file(cert_dst, "wb");
+                ERR(!wb, "%s", cert_dst);
+        }
+        X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
+        ERR(!i2d_X509_bio(wb, x509), cert_dst);
+        if (kbuild_verbose)
+                fprintf(stderr, "Extracted cert: %s\n", buf);
+}
 
 int main(int argc, char **argv)
 {
-        char *cert_src, *cert_dst;
-        X509 *x509;
-        BIO *b;
+        char *cert_src;
 
         OpenSSL_add_all_algorithms();
         ERR_load_crypto_strings();
         ERR_clear_error();
 
+        kbuild_verbose = atoi(getenv("KBUILD_VERBOSE")?:"0");
+
         key_pass = getenv("KBUILD_SIGN_PIN");
 
         if (argc != 3)
@@ -92,7 +109,13 @@ int main(int argc, char **argv)
         cert_src = argv[1];
         cert_dst = argv[2];
 
-        if (!strncmp(cert_src, "pkcs11:", 7)) {
+        if (!cert_src[0]) {
+                /* Invoked with no input; create empty file */
+                FILE *f = fopen(cert_dst, "wb");
+                ERR(!f, "%s", cert_dst);
+                fclose(f);
+                exit(0);
+        } else if (!strncmp(cert_src, "pkcs11:", 7)) {
                 ENGINE *e;
                 struct {
                         const char *cert_id;
@@ -114,19 +137,30 @@ int main(int argc, char **argv)
                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0), "Set PKCS#11 PIN");
                 ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
                 ERR(!parms.cert, "Get X.509 from PKCS#11");
-                x509 = parms.cert;
+                write_cert(parms.cert);
         } else {
+                BIO *b;
+                X509 *x509;
+
                 b = BIO_new_file(cert_src, "rb");
                 ERR(!b, "%s", cert_src);
-                x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
-                ERR(!x509, "%s", cert_src);
-                BIO_free(b);
+
+                while (1) {
+                        x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
+                        if (wb && !x509) {
+                                unsigned long err = ERR_peek_last_error();
+                                if (ERR_GET_LIB(err) == ERR_LIB_PEM &&
+                                    ERR_GET_REASON(err) == PEM_R_NO_START_LINE) {
+                                        ERR_clear_error();
+                                        break;
+                                }
+                        }
+                        ERR(!x509, "%s", cert_src);
+                        write_cert(x509);
+                }
         }
 
-        b = BIO_new_file(cert_dst, "wb");
-        ERR(!b, "%s", cert_dst);
-        ERR(!i2d_X509_bio(b, x509), cert_dst);
-        BIO_free(b);
+        BIO_free(wb);
 
         return 0;
 }