From: Ross Lagerwall Date: Tue, 10 Nov 2015 10:31:55 +0000 (+0000) Subject: Add support for signing payloads X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=9867d245e01b77a8babec961e5721c3f1385a7c1;p=livepatch-build-tools.git Add support for signing payloads Use the module signing infrastructure from Linux 4.3-rc6 to allow signing payloads. Example: $ cd sign $ make $ ./sign-file-wrapper /path/to/payload.xsplice --- diff --git a/.gitignore b/.gitignore index 5561ba5..e53b55e 100644 --- a/.gitignore +++ b/.gitignore @@ -2,3 +2,7 @@ create-diff-object prelink *.o *.d +sign/extract-cert +sign/sign-file +sign/signing_key.pem +sign/signing_key.x509 diff --git a/sign/Makefile b/sign/Makefile new file mode 100644 index 0000000..d29761a --- /dev/null +++ b/sign/Makefile @@ -0,0 +1,76 @@ +SHELL = /bin/sh +CC = gcc + +.PHONY: all install clean distclean +.DEFAULT: all + +CFLAGS += -Iinsn -Wall -g +LDFLAGS = -lcrypto + +CERTS = signing_key.pem signing_key.x509 +TARGETS = sign-file extract-cert $(CERTS) +SIGN_OBJS = sign-file.o +EXTRACT_CERT_OBJS = extract-cert.o +SOURCES = sign-file.c extract-cert.c + +all: $(TARGETS) + +-include $(SOURCES:.c=.d) + +%.o : %.c + $(CC) -MMD -MP $(CFLAGS) -c -o $@ $< + +sign-file: $(SIGN_OBJS) + $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) + +extract-cert: $(EXTRACT_CERT_OBJS) + $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS) + +clean: + $(RM) $(TARGETS) $(SIGN_OBJS) $(EXTRACT_CERT_OBJS) *.d insn/*.d + +distclean: clean + $(RM) $(CERTS) + +# Generate a certificate if needed +# These routines come from Linux. +signing_key.pem: x509.genkey + @echo "###" + @echo "### Now generating an X.509 key pair to be used for signing modules." + @echo "###" + @echo "### If this takes a long time, you might wish to run rngd in the" + @echo "### background to keep the supply of entropy topped up. It" + @echo "### needs to be run as root, and uses a hardware random" + @echo "### number generator if one is available." + @echo "###" + openssl req -new -nodes -utf8 -sha256 -days 36500 \ + -batch -x509 -config x509.genkey \ + -outform PEM -out signing_key.pem \ + -keyout signing_key.pem 2>&1 + @echo "###" + @echo "### Key pair generated." + @echo "###" + +x509.genkey: + @echo Generating X.509 key generation config + @echo >$@ "[ req ]" + @echo >>$@ "default_bits = 4096" + @echo >>$@ "distinguished_name = req_distinguished_name" + @echo >>$@ "prompt = no" + @echo >>$@ "string_mask = utf8only" + @echo >>$@ "x509_extensions = myexts" + @echo >>$@ + @echo >>$@ "[ req_distinguished_name ]" + @echo >>$@ "#O = Unspecified company" + @echo >>$@ "CN = Build time autogenerated kernel key" + @echo >>$@ "#emailAddress = unspecified.user@unspecified.company" + @echo >>$@ + @echo >>$@ "[ myexts ]" + @echo >>$@ "basicConstraints=critical,CA:FALSE" + @echo >>$@ "keyUsage=digitalSignature" + @echo >>$@ "subjectKeyIdentifier=hash" + @echo >>$@ "authorityKeyIdentifier=keyid" +.INTERMEDIATE: x509.genkey + +signing_key.x509: extract-cert signing_key.pem + ./extract-cert signing_key.pem $@ diff --git a/sign/extract-cert.c b/sign/extract-cert.c new file mode 100644 index 0000000..b071bf4 --- /dev/null +++ b/sign/extract-cert.c @@ -0,0 +1,162 @@ +/* Extract X.509 certificate in DER form from PKCS#11 or PEM. + * + * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved. + * Copyright © 2015 Intel Corporation. + * + * Authors: David Howells + * David Woodhouse + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either version 2.1 + * of the licence, or (at your option) any later version. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define PKEY_ID_PKCS7 2 + +static __attribute__((noreturn)) +void format(void) +{ + fprintf(stderr, + "Usage: scripts/extract-cert \n"); + exit(2); +} + +static void display_openssl_errors(int l) +{ + const char *file; + char buf[120]; + int e, line; + + if (ERR_peek_error() == 0) + return; + fprintf(stderr, "At main.c:%d:\n", l); + + while ((e = ERR_get_error_line(&file, &line))) { + ERR_error_string(e, buf); + fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line); + } +} + +static void drain_openssl_errors(void) +{ + const char *file; + int line; + + if (ERR_peek_error() == 0) + return; + while (ERR_get_error_line(&file, &line)) {} +} + +#define ERR(cond, fmt, ...) \ + do { \ + bool __cond = (cond); \ + display_openssl_errors(__LINE__); \ + if (__cond) { \ + err(1, fmt, ## __VA_ARGS__); \ + } \ + } 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), "%s", cert_dst); + if (kbuild_verbose) + fprintf(stderr, "Extracted cert: %s\n", buf); +} + +int main(int argc, char **argv) +{ + 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) + format(); + + cert_src = argv[1]; + cert_dst = argv[2]; + + 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; + X509 *cert; + } parms; + + parms.cert_id = cert_src; + parms.cert = NULL; + + 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"); + ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1); + ERR(!parms.cert, "Get X.509 from PKCS#11"); + write_cert(parms.cert); + } else { + BIO *b; + X509 *x509; + + b = BIO_new_file(cert_src, "rb"); + ERR(!b, "%s", cert_src); + + 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); + } + } + + BIO_free(wb); + + return 0; +} diff --git a/sign/sign-file-wrapper b/sign/sign-file-wrapper new file mode 100755 index 0000000..b006e96 --- /dev/null +++ b/sign/sign-file-wrapper @@ -0,0 +1,6 @@ +#!/bin/bash + +set -e + +./sign-file sha256 signing_key.pem signing_key.x509 "$@" +chmod +x "$@" diff --git a/sign/sign-file.c b/sign/sign-file.c new file mode 100644 index 0000000..1d3f3a7 --- /dev/null +++ b/sign/sign-file.c @@ -0,0 +1,323 @@ +/* Sign a module file using the given key. + * + * Copyright © 2014-2015 Red Hat, Inc. All Rights Reserved. + * Copyright © 2015 Intel Corporation. + * + * Authors: David Howells + * David Woodhouse + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either version 2.1 + * of the licence, or (at your option) any later version. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to + * assume that it's not available and its header file is missing and that we + * should use PKCS#7 instead. Switching to the older PKCS#7 format restricts + * the options we have on specifying the X.509 certificate we want. + * + * Further, older versions of OpenSSL don't support manually adding signers to + * the PKCS#7 message so have to accept that we get a certificate included in + * the signature message. Nor do such older versions of OpenSSL support + * signing with anything other than SHA1 - so we're stuck with that if such is + * the case. + */ +#if OPENSSL_VERSION_NUMBER < 0x10000000L +#define USE_PKCS7 +#endif +#ifndef USE_PKCS7 +#include +#else +#include +#endif + +struct module_signature { + uint8_t algo; /* Public-key crypto algorithm [0] */ + uint8_t hash; /* Digest algorithm [0] */ + uint8_t id_type; /* Key identifier type [PKEY_ID_PKCS7] */ + uint8_t signer_len; /* Length of signer's name [0] */ + uint8_t key_id_len; /* Length of key identifier [0] */ + uint8_t __pad[3]; + uint32_t sig_len; /* Length of signature data */ +}; + +#define PKEY_ID_PKCS7 2 + +static char magic_number[] = "~Module signature appended~\n"; + +static __attribute__((noreturn)) +void format(void) +{ + fprintf(stderr, + "Usage: sign-file [-dp] []\n"); + exit(2); +} + +static void display_openssl_errors(int l) +{ + const char *file; + char buf[120]; + int e, line; + + if (ERR_peek_error() == 0) + return; + fprintf(stderr, "At main.c:%d:\n", l); + + while ((e = ERR_get_error_line(&file, &line))) { + ERR_error_string(e, buf); + fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line); + } +} + +static void drain_openssl_errors(void) +{ + const char *file; + int line; + + if (ERR_peek_error() == 0) + return; + while (ERR_get_error_line(&file, &line)) {} +} + +#define ERR(cond, fmt, ...) \ + do { \ + bool __cond = (cond); \ + display_openssl_errors(__LINE__); \ + if (__cond) { \ + err(1, fmt, ## __VA_ARGS__); \ + } \ + } while(0) + +static const char *key_pass; + +static int pem_pw_cb(char *buf, int len, int w, void *v) +{ + int pwlen; + + if (!key_pass) + return -1; + + pwlen = strlen(key_pass); + if (pwlen >= len) + return -1; + + strcpy(buf, key_pass); + + /* If it's wrong, don't keep trying it. */ + key_pass = NULL; + + return pwlen; +} + +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; + bool save_sig = false, replace_orig; + bool sign_only = 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; + unsigned int use_keyid = 0; +#else + PKCS7 *pkcs7; +#endif + X509 *x509; + BIO *b, *bd = NULL, *bm; + int opt, n; + OpenSSL_add_all_algorithms(); + ERR_load_crypto_strings(); + ERR_clear_error(); + + key_pass = getenv("KBUILD_SIGN_PIN"); + +#ifndef USE_PKCS7 + use_signed_attrs = CMS_NOATTR; +#else + use_signed_attrs = PKCS7_NOATTR; +#endif + + do { + opt = getopt(argc, argv, "dpk"); + switch (opt) { + case 'p': save_sig = true; break; + case 'd': sign_only = true; save_sig = true; break; +#ifndef USE_PKCS7 + case 'k': use_keyid = CMS_USE_KEYID; break; +#endif + case -1: break; + default: format(); + } + } while (opt != -1); + + argc -= optind; + argv += optind; + if (argc < 4 || argc > 5) + format(); + + hash_algo = argv[0]; + private_key_name = argv[1]; + x509_name = argv[2]; + module_name = argv[3]; + if (argc == 5) { + dest_name = argv[4]; + replace_orig = false; + } else { + ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0, + "asprintf"); + replace_orig = true; + } + +#ifdef USE_PKCS7 + if (strcmp(hash_algo, "sha1") != 0) { + fprintf(stderr, "sign-file: %s only supports SHA1 signing\n", + OPENSSL_VERSION_TEXT); + exit(3); + } +#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"); + + bm = BIO_new_file(module_name, "rb"); + ERR(!bm, "%s", module_name); + +#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"); + +#else + 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; + + 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); +#else + ERR(i2d_PKCS7_bio(b, pkcs7) < 0, + "%s", sig_file_name); +#endif + BIO_free(b); + } + + if (sign_only) + return 0; + + /* Append the marker and the PKCS#7 message to the destination file */ + ERR(BIO_reset(bm) < 0, "%s", module_name); + while ((n = BIO_read(bm, buf, sizeof(buf))), + n > 0) { + ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name); + } + ERR(n < 0, "%s", module_name); + module_size = BIO_number_written(bd); + +#ifndef USE_PKCS7 + ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name); +#else + ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name); +#endif + 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); + ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name); + + ERR(BIO_free(bd) < 0, "%s", dest_name); + + /* Finally, if we're signing in place, replace the original. */ + if (replace_orig) + ERR(rename(dest_name, module_name) < 0, "%s", dest_name); + + return 0; +}