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Linux/scripts/sign-file.c

  1 /* Sign a module file using the given key.
  2  *
  3  * Copyright © 2014-2016 Red Hat, Inc. All Rights Reserved.
  4  * Copyright © 2015      Intel Corporation.
  5  * Copyright © 2016      Hewlett Packard Enterprise Development LP
  6  *
  7  * Authors: David Howells <dhowells@redhat.com>
  8  *          David Woodhouse <dwmw2@infradead.org>
  9  *          Juerg Haefliger <juerg.haefliger@hpe.com>
 10  *
 11  * This program is free software; you can redistribute it and/or
 12  * modify it under the terms of the GNU Lesser General Public License
 13  * as published by the Free Software Foundation; either version 2.1
 14  * of the licence, or (at your option) any later version.
 15  */
 16 #define _GNU_SOURCE
 17 #include <stdio.h>
 18 #include <stdlib.h>
 19 #include <stdint.h>
 20 #include <stdbool.h>
 21 #include <string.h>
 22 #include <getopt.h>
 23 #include <err.h>
 24 #include <arpa/inet.h>
 25 #include <openssl/opensslv.h>
 26 #include <openssl/bio.h>
 27 #include <openssl/evp.h>
 28 #include <openssl/pem.h>
 29 #include <openssl/err.h>
 30 #include <openssl/engine.h>
 31 
 32 /*
 33  * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
 34  * assume that it's not available and its header file is missing and that we
 35  * should use PKCS#7 instead.  Switching to the older PKCS#7 format restricts
 36  * the options we have on specifying the X.509 certificate we want.
 37  *
 38  * Further, older versions of OpenSSL don't support manually adding signers to
 39  * the PKCS#7 message so have to accept that we get a certificate included in
 40  * the signature message.  Nor do such older versions of OpenSSL support
 41  * signing with anything other than SHA1 - so we're stuck with that if such is
 42  * the case.
 43  */
 44 #if OPENSSL_VERSION_NUMBER < 0x10000000L || defined(OPENSSL_NO_CMS)
 45 #define USE_PKCS7
 46 #endif
 47 #ifndef USE_PKCS7
 48 #include <openssl/cms.h>
 49 #else
 50 #include <openssl/pkcs7.h>
 51 #endif
 52 
 53 struct module_signature {
 54         uint8_t         algo;           /* Public-key crypto algorithm [0] */
 55         uint8_t         hash;           /* Digest algorithm [0] */
 56         uint8_t         id_type;        /* Key identifier type [PKEY_ID_PKCS7] */
 57         uint8_t         signer_len;     /* Length of signer's name [0] */
 58         uint8_t         key_id_len;     /* Length of key identifier [0] */
 59         uint8_t         __pad[3];
 60         uint32_t        sig_len;        /* Length of signature data */
 61 };
 62 
 63 #define PKEY_ID_PKCS7 2
 64 
 65 static char magic_number[] = "~Module signature appended~\n";
 66 
 67 static __attribute__((noreturn))
 68 void format(void)
 69 {
 70         fprintf(stderr,
 71                 "Usage: scripts/sign-file [-dp] <hash algo> <key> <x509> <module> [<dest>]\n");
 72         fprintf(stderr,
 73                 "       scripts/sign-file -s <raw sig> <hash algo> <x509> <module> [<dest>]\n");
 74         exit(2);
 75 }
 76 
 77 static void display_openssl_errors(int l)
 78 {
 79         const char *file;
 80         char buf[120];
 81         int e, line;
 82 
 83         if (ERR_peek_error() == 0)
 84                 return;
 85         fprintf(stderr, "At main.c:%d:\n", l);
 86 
 87         while ((e = ERR_get_error_line(&file, &line))) {
 88                 ERR_error_string(e, buf);
 89                 fprintf(stderr, "- SSL %s: %s:%d\n", buf, file, line);
 90         }
 91 }
 92 
 93 static void drain_openssl_errors(void)
 94 {
 95         const char *file;
 96         int line;
 97 
 98         if (ERR_peek_error() == 0)
 99                 return;
100         while (ERR_get_error_line(&file, &line)) {}
101 }
102 
103 #define ERR(cond, fmt, ...)                             \
104         do {                                            \
105                 bool __cond = (cond);                   \
106                 display_openssl_errors(__LINE__);       \
107                 if (__cond) {                           \
108                         err(1, fmt, ## __VA_ARGS__);    \
109                 }                                       \
110         } while(0)
111 
112 static const char *key_pass;
113 
114 static int pem_pw_cb(char *buf, int len, int w, void *v)
115 {
116         int pwlen;
117 
118         if (!key_pass)
119                 return -1;
120 
121         pwlen = strlen(key_pass);
122         if (pwlen >= len)
123                 return -1;
124 
125         strcpy(buf, key_pass);
126 
127         /* If it's wrong, don't keep trying it. */
128         key_pass = NULL;
129 
130         return pwlen;
131 }
132 
133 static EVP_PKEY *read_private_key(const char *private_key_name)
134 {
135         EVP_PKEY *private_key;
136 
137         if (!strncmp(private_key_name, "pkcs11:", 7)) {
138                 ENGINE *e;
139 
140                 ENGINE_load_builtin_engines();
141                 drain_openssl_errors();
142                 e = ENGINE_by_id("pkcs11");
143                 ERR(!e, "Load PKCS#11 ENGINE");
144                 if (ENGINE_init(e))
145                         drain_openssl_errors();
146                 else
147                         ERR(1, "ENGINE_init");
148                 if (key_pass)
149                         ERR(!ENGINE_ctrl_cmd_string(e, "PIN", key_pass, 0),
150                             "Set PKCS#11 PIN");
151                 private_key = ENGINE_load_private_key(e, private_key_name,
152                                                       NULL, NULL);
153                 ERR(!private_key, "%s", private_key_name);
154         } else {
155                 BIO *b;
156 
157                 b = BIO_new_file(private_key_name, "rb");
158                 ERR(!b, "%s", private_key_name);
159                 private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
160                                                       NULL);
161                 ERR(!private_key, "%s", private_key_name);
162                 BIO_free(b);
163         }
164 
165         return private_key;
166 }
167 
168 static X509 *read_x509(const char *x509_name)
169 {
170         unsigned char buf[2];
171         X509 *x509;
172         BIO *b;
173         int n;
174 
175         b = BIO_new_file(x509_name, "rb");
176         ERR(!b, "%s", x509_name);
177 
178         /* Look at the first two bytes of the file to determine the encoding */
179         n = BIO_read(b, buf, 2);
180         if (n != 2) {
181                 if (BIO_should_retry(b)) {
182                         fprintf(stderr, "%s: Read wanted retry\n", x509_name);
183                         exit(1);
184                 }
185                 if (n >= 0) {
186                         fprintf(stderr, "%s: Short read\n", x509_name);
187                         exit(1);
188                 }
189                 ERR(1, "%s", x509_name);
190         }
191 
192         ERR(BIO_reset(b) != 0, "%s", x509_name);
193 
194         if (buf[0] == 0x30 && buf[1] >= 0x81 && buf[1] <= 0x84)
195                 /* Assume raw DER encoded X.509 */
196                 x509 = d2i_X509_bio(b, NULL);
197         else
198                 /* Assume PEM encoded X.509 */
199                 x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
200 
201         BIO_free(b);
202         ERR(!x509, "%s", x509_name);
203 
204         return x509;
205 }
206 
207 int main(int argc, char **argv)
208 {
209         struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };
210         char *hash_algo = NULL;
211         char *private_key_name = NULL, *raw_sig_name = NULL;
212         char *x509_name, *module_name, *dest_name;
213         bool save_sig = false, replace_orig;
214         bool sign_only = false;
215         bool raw_sig = false;
216         unsigned char buf[4096];
217         unsigned long module_size, sig_size;
218         unsigned int use_signed_attrs;
219         const EVP_MD *digest_algo;
220         EVP_PKEY *private_key;
221 #ifndef USE_PKCS7
222         CMS_ContentInfo *cms = NULL;
223         unsigned int use_keyid = 0;
224 #else
225         PKCS7 *pkcs7 = NULL;
226 #endif
227         X509 *x509;
228         BIO *bd, *bm;
229         int opt, n;
230         OpenSSL_add_all_algorithms();
231         ERR_load_crypto_strings();
232         ERR_clear_error();
233 
234         key_pass = getenv("KBUILD_SIGN_PIN");
235 
236 #ifndef USE_PKCS7
237         use_signed_attrs = CMS_NOATTR;
238 #else
239         use_signed_attrs = PKCS7_NOATTR;
240 #endif
241 
242         do {
243                 opt = getopt(argc, argv, "sdpk");
244                 switch (opt) {
245                 case 's': raw_sig = true; break;
246                 case 'p': save_sig = true; break;
247                 case 'd': sign_only = true; save_sig = true; break;
248 #ifndef USE_PKCS7
249                 case 'k': use_keyid = CMS_USE_KEYID; break;
250 #endif
251                 case -1: break;
252                 default: format();
253                 }
254         } while (opt != -1);
255 
256         argc -= optind;
257         argv += optind;
258         if (argc < 4 || argc > 5)
259                 format();
260 
261         if (raw_sig) {
262                 raw_sig_name = argv[0];
263                 hash_algo = argv[1];
264         } else {
265                 hash_algo = argv[0];
266                 private_key_name = argv[1];
267         }
268         x509_name = argv[2];
269         module_name = argv[3];
270         if (argc == 5 && strcmp(argv[3], argv[4]) != 0) {
271                 dest_name = argv[4];
272                 replace_orig = false;
273         } else {
274                 ERR(asprintf(&dest_name, "%s.~signed~", module_name) < 0,
275                     "asprintf");
276                 replace_orig = true;
277         }
278 
279 #ifdef USE_PKCS7
280         if (strcmp(hash_algo, "sha1") != 0) {
281                 fprintf(stderr, "sign-file: %s only supports SHA1 signing\n",
282                         OPENSSL_VERSION_TEXT);
283                 exit(3);
284         }
285 #endif
286 
287         /* Open the module file */
288         bm = BIO_new_file(module_name, "rb");
289         ERR(!bm, "%s", module_name);
290 
291         if (!raw_sig) {
292                 /* Read the private key and the X.509 cert the PKCS#7 message
293                  * will point to.
294                  */
295                 private_key = read_private_key(private_key_name);
296                 x509 = read_x509(x509_name);
297 
298                 /* Digest the module data. */
299                 OpenSSL_add_all_digests();
300                 display_openssl_errors(__LINE__);
301                 digest_algo = EVP_get_digestbyname(hash_algo);
302                 ERR(!digest_algo, "EVP_get_digestbyname");
303 
304 #ifndef USE_PKCS7
305                 /* Load the signature message from the digest buffer. */
306                 cms = CMS_sign(NULL, NULL, NULL, NULL,
307                                CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY |
308                                CMS_DETACHED | CMS_STREAM);
309                 ERR(!cms, "CMS_sign");
310 
311                 ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,
312                                      CMS_NOCERTS | CMS_BINARY |
313                                      CMS_NOSMIMECAP | use_keyid |
314                                      use_signed_attrs),
315                     "CMS_add1_signer");
316                 ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,
317                     "CMS_final");
318 
319 #else
320                 pkcs7 = PKCS7_sign(x509, private_key, NULL, bm,
321                                    PKCS7_NOCERTS | PKCS7_BINARY |
322                                    PKCS7_DETACHED | use_signed_attrs);
323                 ERR(!pkcs7, "PKCS7_sign");
324 #endif
325 
326                 if (save_sig) {
327                         char *sig_file_name;
328                         BIO *b;
329 
330                         ERR(asprintf(&sig_file_name, "%s.p7s", module_name) < 0,
331                             "asprintf");
332                         b = BIO_new_file(sig_file_name, "wb");
333                         ERR(!b, "%s", sig_file_name);
334 #ifndef USE_PKCS7
335                         ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0,
336                             "%s", sig_file_name);
337 #else
338                         ERR(i2d_PKCS7_bio(b, pkcs7) < 0,
339                             "%s", sig_file_name);
340 #endif
341                         BIO_free(b);
342                 }
343 
344                 if (sign_only) {
345                         BIO_free(bm);
346                         return 0;
347                 }
348         }
349 
350         /* Open the destination file now so that we can shovel the module data
351          * across as we read it.
352          */
353         bd = BIO_new_file(dest_name, "wb");
354         ERR(!bd, "%s", dest_name);
355 
356         /* Append the marker and the PKCS#7 message to the destination file */
357         ERR(BIO_reset(bm) < 0, "%s", module_name);
358         while ((n = BIO_read(bm, buf, sizeof(buf))),
359                n > 0) {
360                 ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
361         }
362         BIO_free(bm);
363         ERR(n < 0, "%s", module_name);
364         module_size = BIO_number_written(bd);
365 
366         if (!raw_sig) {
367 #ifndef USE_PKCS7
368                 ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);
369 #else
370                 ERR(i2d_PKCS7_bio(bd, pkcs7) < 0, "%s", dest_name);
371 #endif
372         } else {
373                 BIO *b;
374 
375                 /* Read the raw signature file and write the data to the
376                  * destination file
377                  */
378                 b = BIO_new_file(raw_sig_name, "rb");
379                 ERR(!b, "%s", raw_sig_name);
380                 while ((n = BIO_read(b, buf, sizeof(buf))), n > 0)
381                         ERR(BIO_write(bd, buf, n) < 0, "%s", dest_name);
382                 BIO_free(b);
383         }
384 
385         sig_size = BIO_number_written(bd) - module_size;
386         sig_info.sig_len = htonl(sig_size);
387         ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);
388         ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);
389 
390         ERR(BIO_free(bd) < 0, "%s", dest_name);
391 
392         /* Finally, if we're signing in place, replace the original. */
393         if (replace_orig)
394                 ERR(rename(dest_name, module_name) < 0, "%s", dest_name);
395 
396         return 0;
397 }
398 

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