1 /*-
2 * Copyright (c) 2014 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * This software was developed by Edward Tomasz Napierala under sponsorship
6 * from the FreeBSD Foundation.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33
34 #include <sys/param.h>
35 #if __FreeBSD_version >= 1100000
36 #include <sys/capsicum.h>
37 #else
38 #include <sys/capability.h>
39 #endif
40 #include <sys/types.h>
41 #include <sys/stat.h>
42 #include <assert.h>
43 #include <err.h>
44 #include <errno.h>
45 #include <stdio.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <unistd.h>
49
50 #include <openssl/evp.h>
51 #include <openssl/err.h>
52 #include <openssl/pem.h>
53
54 #include "uefisign.h"
55
56 static void
load(struct executable * x)57 load(struct executable *x)
58 {
59 int error, fd;
60 struct stat sb;
61 char *buf;
62 size_t nread, len;
63
64 fd = fileno(x->x_fp);
65
66 error = fstat(fd, &sb);
67 if (error != 0)
68 err(1, "%s: fstat", x->x_path);
69
70 len = sb.st_size;
71 if (len <= 0)
72 errx(1, "%s: file is empty", x->x_path);
73
74 buf = malloc(len);
75 if (buf == NULL)
76 err(1, "%s: cannot malloc %zd bytes", x->x_path, len);
77
78 nread = fread(buf, len, 1, x->x_fp);
79 if (nread != 1)
80 err(1, "%s: fread", x->x_path);
81
82 x->x_buf = buf;
83 x->x_len = len;
84 }
85
86 static void
digest_range(struct executable * x,EVP_MD_CTX * mdctx,off_t off,size_t len)87 digest_range(struct executable *x, EVP_MD_CTX *mdctx, off_t off, size_t len)
88 {
89 int ok;
90
91 range_check(x, off, len, "chunk");
92
93 ok = EVP_DigestUpdate(mdctx, x->x_buf + off, len);
94 if (ok == 0) {
95 ERR_print_errors_fp(stderr);
96 errx(1, "EVP_DigestUpdate(3) failed");
97 }
98 }
99
100 static void
digest(struct executable * x)101 digest(struct executable *x)
102 {
103 EVP_MD_CTX *mdctx;
104 const EVP_MD *md;
105 size_t sum_of_bytes_hashed;
106 int i, ok;
107
108 /*
109 * Windows Authenticode Portable Executable Signature Format
110 * spec version 1.0 specifies MD5 and SHA1. However, pesign
111 * and sbsign both use SHA256, so do the same.
112 */
113 md = EVP_get_digestbyname(DIGEST);
114 if (md == NULL) {
115 ERR_print_errors_fp(stderr);
116 errx(1, "EVP_get_digestbyname(\"%s\") failed", DIGEST);
117 }
118
119 mdctx = EVP_MD_CTX_create();
120 if (mdctx == NULL) {
121 ERR_print_errors_fp(stderr);
122 errx(1, "EVP_MD_CTX_create(3) failed");
123 }
124
125 ok = EVP_DigestInit_ex(mdctx, md, NULL);
126 if (ok == 0) {
127 ERR_print_errors_fp(stderr);
128 errx(1, "EVP_DigestInit_ex(3) failed");
129 }
130
131 /*
132 * According to the Authenticode spec, we need to compute
133 * the digest in a rather... specific manner; see "Calculating
134 * the PE Image Hash" part of the spec for details.
135 *
136 * First, everything from 0 to before the PE checksum.
137 */
138 digest_range(x, mdctx, 0, x->x_checksum_off);
139
140 /*
141 * Second, from after the PE checksum to before the Certificate
142 * entry in Data Directory.
143 */
144 digest_range(x, mdctx, x->x_checksum_off + x->x_checksum_len,
145 x->x_certificate_entry_off -
146 (x->x_checksum_off + x->x_checksum_len));
147
148 /*
149 * Then, from after the Certificate entry to the end of headers.
150 */
151 digest_range(x, mdctx,
152 x->x_certificate_entry_off + x->x_certificate_entry_len,
153 x->x_headers_len -
154 (x->x_certificate_entry_off + x->x_certificate_entry_len));
155
156 /*
157 * Then, each section in turn, as specified in the PE Section Table.
158 *
159 * XXX: Sorting.
160 */
161 sum_of_bytes_hashed = x->x_headers_len;
162 for (i = 0; i < x->x_nsections; i++) {
163 digest_range(x, mdctx,
164 x->x_section_off[i], x->x_section_len[i]);
165 sum_of_bytes_hashed += x->x_section_len[i];
166 }
167
168 /*
169 * I believe this can happen with overlapping sections.
170 */
171 if (sum_of_bytes_hashed > x->x_len)
172 errx(1, "number of bytes hashed is larger than file size");
173
174 /*
175 * I can't really explain this one; just do what the spec says.
176 */
177 if (sum_of_bytes_hashed < x->x_len) {
178 digest_range(x, mdctx, sum_of_bytes_hashed,
179 x->x_len - (signature_size(x) + sum_of_bytes_hashed));
180 }
181
182 ok = EVP_DigestFinal_ex(mdctx, x->x_digest, &x->x_digest_len);
183 if (ok == 0) {
184 ERR_print_errors_fp(stderr);
185 errx(1, "EVP_DigestFinal_ex(3) failed");
186 }
187
188 EVP_MD_CTX_destroy(mdctx);
189 }
190
191 static void
show_digest(const struct executable * x)192 show_digest(const struct executable *x)
193 {
194 int i;
195
196 printf("computed %s digest ", DIGEST);
197 for (i = 0; i < (int)x->x_digest_len; i++)
198 printf("%02x", (unsigned char)x->x_digest[i]);
199 printf("; digest len %u\n", x->x_digest_len);
200 }
201
202 static void
send_digest(const struct executable * x,int pipefd)203 send_digest(const struct executable *x, int pipefd)
204 {
205
206 send_chunk(x->x_digest, x->x_digest_len, pipefd);
207 }
208
209 static void
receive_signature(struct executable * x,int pipefd)210 receive_signature(struct executable *x, int pipefd)
211 {
212
213 receive_chunk(&x->x_signature, &x->x_signature_len, pipefd);
214 }
215
216 static void
save(struct executable * x,FILE * fp,const char * path)217 save(struct executable *x, FILE *fp, const char *path)
218 {
219 size_t nwritten;
220
221 assert(fp != NULL);
222 assert(path != NULL);
223
224 nwritten = fwrite(x->x_buf, x->x_len, 1, fp);
225 if (nwritten != 1)
226 err(1, "%s: fwrite", path);
227 }
228
229 int
child(const char * inpath,const char * outpath,int pipefd,bool Vflag,bool vflag)230 child(const char *inpath, const char *outpath, int pipefd,
231 bool Vflag, bool vflag)
232 {
233 int error;
234 FILE *outfp = NULL, *infp = NULL;
235 struct executable *x;
236
237 infp = checked_fopen(inpath, "r");
238 if (outpath != NULL)
239 outfp = checked_fopen(outpath, "w");
240
241 error = cap_enter();
242 if (error != 0 && errno != ENOSYS)
243 err(1, "cap_enter");
244
245 x = calloc(1, sizeof(*x));
246 if (x == NULL)
247 err(1, "calloc");
248 x->x_path = inpath;
249 x->x_fp = infp;
250
251 load(x);
252 parse(x);
253 if (Vflag) {
254 if (signature_size(x) == 0)
255 errx(1, "file not signed");
256
257 printf("file contains signature\n");
258 if (vflag) {
259 digest(x);
260 show_digest(x);
261 show_certificate(x);
262 }
263 } else {
264 if (signature_size(x) != 0)
265 errx(1, "file already signed");
266
267 digest(x);
268 if (vflag)
269 show_digest(x);
270 send_digest(x, pipefd);
271 receive_signature(x, pipefd);
272 update(x);
273 save(x, outfp, outpath);
274 }
275
276 return (0);
277 }
278