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1.3 ! tedu 1: /* $OpenBSD: zsig.c,v 1.2 2016/09/02 16:12:09 espie Exp $ */
1.1 espie 2: /*
3: * Copyright (c) 2016 Marc Espie <espie@openbsd.org>
4: *
5: * Permission to use, copy, modify, and distribute this software for any
6: * purpose with or without fee is hereby granted, provided that the above
7: * copyright notice and this permission notice appear in all copies.
8: *
9: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16: */
17:
18: #ifndef VERIFYONLY
19: #include <stdint.h>
20: #include <err.h>
21: #include <stdio.h>
22: #include <stdlib.h>
23: #include <unistd.h>
24: #include <sha2.h>
25: #include <string.h>
26: #include <sys/stat.h>
27: #include <fcntl.h>
28: #include "signify.h"
29:
30: struct gzheader {
31: uint8_t flg;
32: uint32_t mtime;
33: uint8_t xflg;
34: uint8_t os;
35: uint8_t *name;
36: uint8_t *comment;
37: uint8_t *endcomment;
38: unsigned long long headerlength;
39: };
40:
41: #define FTEXT_FLAG 1
42: #define FHCRC_FLAG 2
43: #define FEXTRA_FLAG 4
44: #define FNAME_FLAG 8
45: #define FCOMMENT_FLAG 16
46:
47: #define MYBUFSIZE 65536LU
48:
49:
50: static uint8_t fake[10] = { 0x1f, 0x8b, 8, 0, 0, 0, 0, 0, 0, 3 };
51:
52: /* XXX no static there, confuses the hell out of gcc which displays
53: * non-existent warnings.
54: */
55: uint8_t *
56: readgz_header(struct gzheader *h, int fd)
57: {
58: size_t sz = 1024;
59: uint8_t *p;
60: size_t pos = 0;
61: size_t len = 0;
62: int state = 0;
63: ssize_t n;
64: uint8_t *buf = xmalloc(sz);
65:
66: if (!buf)
67: exit(1);
68:
69: while (1) {
70: if (len == sz) {
71: sz *= 2;
72: buf = realloc(buf, sz);
73: if (!buf)
1.3 ! tedu 74: err(1, "realloc");
1.1 espie 75: }
76: n = read(fd, buf+len, sz-len);
77: if (n == -1)
1.3 ! tedu 78: err(1, "read");
1.1 espie 79: /* incomplete info */
80: if (n == 0)
1.3 ! tedu 81: errx(1, "gzheader truncated");
1.1 espie 82: len += n;
83: h->comment = NULL;
84: h->name = NULL;
85:
86: switch(state) {
87: case 0: /* check header proper */
88: /* need ten bytes */
89: if (len < 10)
90: continue;
91: h->flg = buf[3];
92: h->mtime = buf[4] | (buf[5] << 8U) | (buf[6] << 16U) |
93: (buf[7] << 24U);
94: h->xflg = buf[8];
95: h->os = buf[9];
96: /* magic gzip header */
97: if (buf[0] != 0x1f || buf[1] != 0x8b || buf[2] != 8)
1.3 ! tedu 98: err(1, "invalud magic in gzheader");
1.1 espie 99: /* XXX special code that only caters to our needs */
100: if (h->flg & ~ (FCOMMENT_FLAG | FNAME_FLAG))
1.3 ! tedu 101: err(1, "invalid flags in gzheader");
1.1 espie 102: pos = 10;
103: state++;
104: /*FALLTHRU*/
105: case 1:
106: if (h->flg & FNAME_FLAG) {
107: p = memchr(buf+pos, 0, len - pos);
108: if (!p)
109: continue;
110: h->name = buf + pos;
111: pos = (p - buf) + 1;
112: }
113: state++;
114: /*FALLTHRU*/
115: case 2:
116: if (h->flg & FCOMMENT_FLAG) {
117: p = memchr(buf+pos, 0, len - pos);
118: if (!p)
119: continue;
120: h->comment = buf + pos;
121: h->endcomment = p;
122: pos = (p - buf) + 1;
123: }
124: h->headerlength = pos;
125: return buf + len;
126: }
127:
128: }
129: }
130:
131: static void
132: copy_blocks(int fdout, int fdin, const char *sha, const char *endsha,
133: size_t bufsize, uint8_t *bufend)
134: {
135: uint8_t *buffer = xmalloc(bufsize);
136:
137: uint8_t *residual = (uint8_t *)endsha+1;
138: uint8_t output[SHA256_DIGEST_STRING_LENGTH];
139: while (1) {
140: /* get the next block */
141: size_t n = 0;
142: /* if we have residual data, we use it */
143: if (residual != bufend) {
144: /* how much can we copy */
145: size_t len = bufend - residual;
146: if (len >= bufsize) {
147: memcpy(buffer, residual, bufsize);
148: n = bufsize;
149: residual += bufsize;
150: } else {
151: memcpy(buffer, residual, len);
152: residual += len;
153: n = len;
154: }
155: }
156: /* if we're not done yet, try to obtain more until EOF */
157: while (n != bufsize) {
158: ssize_t more = read(fdin, buffer+n, bufsize-n);
159: if (more == -1)
1.3 ! tedu 160: err(1, "read");
1.1 espie 161: n += more;
162: if (more == 0)
163: break;
164: }
165: SHA256Data(buffer, n, output);
166: if (endsha - sha < SHA256_DIGEST_STRING_LENGTH-1)
167: errx(4, "signature truncated");
168: if (memcmp(output, sha, SHA256_DIGEST_STRING_LENGTH-1) != 0)
169: errx(4, "signature mismatch");
170: if (sha[SHA256_DIGEST_STRING_LENGTH-1] != '\n')
171: errx(4, "signature mismatch");
172: sha += SHA256_DIGEST_STRING_LENGTH;
173: writeall(fdout, buffer, n, "stdout");
174: if (n != bufsize)
175: break;
176: }
177: free(buffer);
178: }
179:
180: void
181: zverify(const char *pubkeyfile, const char *msgfile, const char *sigfile,
182: const char *keytype)
183: {
184: struct gzheader h;
185: size_t bufsize;
186: char *p;
187: uint8_t *bufend;
188: int fdin, fdout;
189: /* by default, verification will love pipes */
190: if (!sigfile)
191: sigfile = "-";
192: if (!msgfile)
193: msgfile = "-";
194:
195: fdin = xopen(sigfile, O_RDONLY | O_NOFOLLOW, 0);
196:
197: bufend = readgz_header(&h, fdin);
198: if (!(h.flg & FCOMMENT_FLAG))
199: errx(1, "%s is an unsigned archive", sigfile);
200: fake[8] = h.xflg;
201:
202: p = verifyzdata(h.comment, h.endcomment-h.comment, sigfile,
203: pubkeyfile, keytype);
204:
205: bufsize = MYBUFSIZE;
206:
207: /* allow for arbitrary blocksize */
208: if (sscanf(p, "blocksize=%zu\n", &bufsize)) {
209: while (*(p++) != '\n')
210: continue;
211: }
212: fdout = xopen(msgfile, O_CREAT|O_TRUNC|O_NOFOLLOW|O_WRONLY, 0666);
213: /* we don't actually copy the header, but put in a fake one with about
214: * zero useful information.
215: */
216: writeall(fdout, fake, sizeof fake, msgfile);
217: copy_blocks(fdout, fdin, p, h.endcomment, bufsize, bufend);
218: close(fdout);
219: close(fdin);
220: }
221:
222: void
223: zsign(const char *seckeyfile, const char *msgfile, const char *sigfile)
224: {
225: size_t bufsize = MYBUFSIZE;
226: int fdin, fdout;
227: struct gzheader h;
228: struct stat sb;
229: size_t space;
230: char *msg;
231: char *p;
232: uint8_t *buffer;
233: uint8_t *sighdr;
234:
235: fdin = xopen(msgfile, O_RDONLY, 0);
236: if (fstat(fdin, &sb) == -1 || !S_ISREG(sb.st_mode))
237: errx(1, "Sorry can only sign regular files");
238:
239: readgz_header(&h, fdin);
240:
241: if (lseek(fdin, h.headerlength, SEEK_SET) == -1)
242: err(1, "seek in %s", msgfile);
243:
244: space = (sb.st_size / MYBUFSIZE) * SHA256_DIGEST_STRING_LENGTH +
245: 80; /* long enough for blocksize=.... */
246:
247: msg = xmalloc(space);
248: buffer = xmalloc(bufsize);
249: snprintf(msg, space, "blocksize=%zu\n", bufsize);
250: p = strchr(msg, 0);
251:
252: while (1) {
253: size_t n = read(fdin, buffer, bufsize);
254: if (n == -1)
255: err(1, "read from %s", msgfile);
256: if (n == 0)
257: break;
258: SHA256Data(buffer, n, p);
259: p += SHA256_DIGEST_STRING_LENGTH;
260: p[-1] = '\n';
261: if (msg + space < p)
262: errx(1, "file too long %s", msgfile);
263: }
264: *p = 0;
265:
266: fdout = xopen(sigfile, O_CREAT|O_TRUNC|O_NOFOLLOW|O_WRONLY, 0666);
267: sighdr = createsig(seckeyfile, msgfile, msg, p-msg);
268: fake[3] = FCOMMENT_FLAG;
269: fake[8] = h.xflg;
270:
271: writeall(fdout, fake, sizeof fake, sigfile);
272: writeall(fdout, sighdr, strlen(sighdr), sigfile);
273: free(sighdr);
274: /* need the 0 ! */
275: writeall(fdout, msg, p - msg + 1, sigfile);
276: free(msg);
277:
278: if (lseek(fdin, h.headerlength, SEEK_SET) == -1)
279: err(1, "seek in %s", msgfile);
280:
281: while (1) {
282: size_t n = read(fdin, buffer, bufsize);
283: if (n == -1)
284: err(1, "read from %s", msgfile);
285: if (n == 0)
286: break;
287: writeall(fdout, buffer, n, sigfile);
288: }
289: free(buffer);
290: close(fdout);
291: }
292:
293: #endif