Annotation of src/usr.bin/ssh/sshsig.c, Revision 1.19
1.19 ! djm 1: /* $OpenBSD: sshsig.c,v 1.18 2020/10/18 11:32:02 djm Exp $ */
1.1 djm 2: /*
3: * Copyright (c) 2019 Google LLC
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: #include <stdio.h>
19: #include <stdlib.h>
20: #include <stdarg.h>
21: #include <errno.h>
22: #include <string.h>
23: #include <unistd.h>
24:
25: #include "authfd.h"
26: #include "authfile.h"
27: #include "log.h"
28: #include "misc.h"
29: #include "sshbuf.h"
30: #include "sshsig.h"
31: #include "ssherr.h"
32: #include "sshkey.h"
33: #include "match.h"
34: #include "digest.h"
35:
36: #define SIG_VERSION 0x01
37: #define MAGIC_PREAMBLE "SSHSIG"
38: #define MAGIC_PREAMBLE_LEN (sizeof(MAGIC_PREAMBLE) - 1)
39: #define BEGIN_SIGNATURE "-----BEGIN SSH SIGNATURE-----\n"
40: #define END_SIGNATURE "-----END SSH SIGNATURE-----"
41: #define RSA_SIGN_ALG "rsa-sha2-512" /* XXX maybe make configurable */
42: #define RSA_SIGN_ALLOWED "rsa-sha2-512,rsa-sha2-256"
43: #define HASHALG_DEFAULT "sha512" /* XXX maybe make configurable */
44: #define HASHALG_ALLOWED "sha256,sha512"
45:
46: int
47: sshsig_armor(const struct sshbuf *blob, struct sshbuf **out)
48: {
49: struct sshbuf *buf = NULL;
50: int r = SSH_ERR_INTERNAL_ERROR;
51:
52: *out = NULL;
53:
54: if ((buf = sshbuf_new()) == NULL) {
1.18 djm 55: error_f("sshbuf_new failed");
1.1 djm 56: r = SSH_ERR_ALLOC_FAIL;
57: goto out;
58: }
59:
60: if ((r = sshbuf_put(buf, BEGIN_SIGNATURE,
61: sizeof(BEGIN_SIGNATURE)-1)) != 0) {
1.18 djm 62: error_fr(r, "sshbuf_putf");
1.1 djm 63: goto out;
64: }
65:
66: if ((r = sshbuf_dtob64(blob, buf, 1)) != 0) {
1.18 djm 67: error_fr(r, "base64 encode signature");
1.1 djm 68: goto out;
69: }
70:
71: if ((r = sshbuf_put(buf, END_SIGNATURE,
72: sizeof(END_SIGNATURE)-1)) != 0 ||
73: (r = sshbuf_put_u8(buf, '\n')) != 0) {
1.18 djm 74: error_fr(r, "sshbuf_put");
1.1 djm 75: goto out;
76: }
77: /* success */
78: *out = buf;
79: buf = NULL; /* transferred */
80: r = 0;
81: out:
82: sshbuf_free(buf);
83: return r;
84: }
85:
86: int
87: sshsig_dearmor(struct sshbuf *sig, struct sshbuf **out)
88: {
89: int r;
90: size_t eoffset = 0;
91: struct sshbuf *buf = NULL;
92: struct sshbuf *sbuf = NULL;
93: char *b64 = NULL;
94:
95: if ((sbuf = sshbuf_fromb(sig)) == NULL) {
1.18 djm 96: error_f("sshbuf_fromb failed");
1.1 djm 97: return SSH_ERR_ALLOC_FAIL;
98: }
99:
100: if ((r = sshbuf_cmp(sbuf, 0,
101: BEGIN_SIGNATURE, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
102: error("Couldn't parse signature: missing header");
103: goto done;
104: }
105:
106: if ((r = sshbuf_consume(sbuf, sizeof(BEGIN_SIGNATURE)-1)) != 0) {
1.18 djm 107: error_fr(r, "consume");
1.1 djm 108: goto done;
109: }
110:
111: if ((r = sshbuf_find(sbuf, 0, "\n" END_SIGNATURE,
112: sizeof("\n" END_SIGNATURE)-1, &eoffset)) != 0) {
113: error("Couldn't parse signature: missing footer");
114: goto done;
115: }
116:
117: if ((r = sshbuf_consume_end(sbuf, sshbuf_len(sbuf)-eoffset)) != 0) {
1.18 djm 118: error_fr(r, "consume");
1.1 djm 119: goto done;
120: }
121:
122: if ((b64 = sshbuf_dup_string(sbuf)) == NULL) {
1.18 djm 123: error_f("sshbuf_dup_string failed");
1.1 djm 124: r = SSH_ERR_ALLOC_FAIL;
125: goto done;
126: }
127:
128: if ((buf = sshbuf_new()) == NULL) {
1.18 djm 129: error_f("sshbuf_new() failed");
1.1 djm 130: r = SSH_ERR_ALLOC_FAIL;
131: goto done;
132: }
133:
134: if ((r = sshbuf_b64tod(buf, b64)) != 0) {
1.18 djm 135: error_fr(r, "decode base64");
1.1 djm 136: goto done;
137: }
138:
139: /* success */
140: *out = buf;
141: r = 0;
142: buf = NULL; /* transferred */
143: done:
144: sshbuf_free(buf);
145: sshbuf_free(sbuf);
146: free(b64);
147: return r;
148: }
149:
150: static int
151: sshsig_wrap_sign(struct sshkey *key, const char *hashalg,
1.16 djm 152: const char *sk_provider, const char *sk_pin, const struct sshbuf *h_message,
1.7 djm 153: const char *sig_namespace, struct sshbuf **out,
154: sshsig_signer *signer, void *signer_ctx)
1.1 djm 155: {
156: int r;
157: size_t slen = 0;
158: u_char *sig = NULL;
159: struct sshbuf *blob = NULL;
160: struct sshbuf *tosign = NULL;
161: const char *sign_alg = NULL;
162:
163: if ((tosign = sshbuf_new()) == NULL ||
164: (blob = sshbuf_new()) == NULL) {
1.18 djm 165: error_f("sshbuf_new failed");
1.1 djm 166: r = SSH_ERR_ALLOC_FAIL;
167: goto done;
168: }
169:
170: if ((r = sshbuf_put(tosign, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
171: (r = sshbuf_put_cstring(tosign, sig_namespace)) != 0 ||
172: (r = sshbuf_put_string(tosign, NULL, 0)) != 0 || /* reserved */
173: (r = sshbuf_put_cstring(tosign, hashalg)) != 0 ||
1.6 djm 174: (r = sshbuf_put_stringb(tosign, h_message)) != 0) {
1.18 djm 175: error_fr(r, "assemble message to sign");
1.1 djm 176: goto done;
177: }
178:
179: /* If using RSA keys then default to a good signature algorithm */
180: if (sshkey_type_plain(key->type) == KEY_RSA)
181: sign_alg = RSA_SIGN_ALG;
182:
183: if (signer != NULL) {
184: if ((r = signer(key, &sig, &slen,
185: sshbuf_ptr(tosign), sshbuf_len(tosign),
1.16 djm 186: sign_alg, sk_provider, sk_pin, 0, signer_ctx)) != 0) {
1.18 djm 187: error_r(r, "Couldn't sign message (signer)");
1.1 djm 188: goto done;
189: }
190: } else {
191: if ((r = sshkey_sign(key, &sig, &slen,
192: sshbuf_ptr(tosign), sshbuf_len(tosign),
1.16 djm 193: sign_alg, sk_provider, sk_pin, 0)) != 0) {
1.18 djm 194: error_r(r, "Couldn't sign message");
1.1 djm 195: goto done;
196: }
197: }
198:
199: if ((r = sshbuf_put(blob, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
200: (r = sshbuf_put_u32(blob, SIG_VERSION)) != 0 ||
201: (r = sshkey_puts(key, blob)) != 0 ||
202: (r = sshbuf_put_cstring(blob, sig_namespace)) != 0 ||
203: (r = sshbuf_put_string(blob, NULL, 0)) != 0 || /* reserved */
204: (r = sshbuf_put_cstring(blob, hashalg)) != 0 ||
205: (r = sshbuf_put_string(blob, sig, slen)) != 0) {
1.18 djm 206: error_fr(r, "assemble signature object");
1.1 djm 207: goto done;
208: }
209:
1.12 markus 210: if (out != NULL) {
211: *out = blob;
212: blob = NULL;
213: }
1.1 djm 214: r = 0;
215: done:
216: free(sig);
217: sshbuf_free(blob);
218: sshbuf_free(tosign);
219: return r;
220: }
221:
222: /* Check preamble and version. */
223: static int
224: sshsig_parse_preamble(struct sshbuf *buf)
225: {
226: int r = SSH_ERR_INTERNAL_ERROR;
227: uint32_t sversion;
228:
229: if ((r = sshbuf_cmp(buf, 0, MAGIC_PREAMBLE, MAGIC_PREAMBLE_LEN)) != 0 ||
230: (r = sshbuf_consume(buf, (sizeof(MAGIC_PREAMBLE)-1))) != 0 ||
231: (r = sshbuf_get_u32(buf, &sversion)) != 0) {
232: error("Couldn't verify signature: invalid format");
233: return r;
234: }
235:
1.2 djm 236: if (sversion > SIG_VERSION) {
1.1 djm 237: error("Signature version %lu is larger than supported "
238: "version %u", (unsigned long)sversion, SIG_VERSION);
239: return SSH_ERR_INVALID_FORMAT;
240: }
241: return 0;
242: }
243:
244: static int
245: sshsig_check_hashalg(const char *hashalg)
246: {
1.2 djm 247: if (hashalg == NULL ||
248: match_pattern_list(hashalg, HASHALG_ALLOWED, 0) == 1)
1.1 djm 249: return 0;
1.18 djm 250: error_f("unsupported hash algorithm \"%.100s\"", hashalg);
1.1 djm 251: return SSH_ERR_SIGN_ALG_UNSUPPORTED;
252: }
253:
254: static int
255: sshsig_peek_hashalg(struct sshbuf *signature, char **hashalgp)
256: {
257: struct sshbuf *buf = NULL;
258: char *hashalg = NULL;
259: int r = SSH_ERR_INTERNAL_ERROR;
260:
261: if (hashalgp != NULL)
262: *hashalgp = NULL;
263: if ((buf = sshbuf_fromb(signature)) == NULL)
264: return SSH_ERR_ALLOC_FAIL;
265: if ((r = sshsig_parse_preamble(buf)) != 0)
266: goto done;
267: if ((r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
268: (r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0 ||
269: (r = sshbuf_get_string(buf, NULL, NULL)) != 0 ||
270: (r = sshbuf_get_cstring(buf, &hashalg, NULL)) != 0 ||
271: (r = sshbuf_get_string_direct(buf, NULL, NULL)) != 0) {
1.18 djm 272: error_fr(r, "parse signature object");
1.1 djm 273: goto done;
274: }
275:
276: /* success */
277: r = 0;
278: *hashalgp = hashalg;
279: hashalg = NULL;
280: done:
281: free(hashalg);
282: sshbuf_free(buf);
283: return r;
284: }
285:
286: static int
287: sshsig_wrap_verify(struct sshbuf *signature, const char *hashalg,
288: const struct sshbuf *h_message, const char *expect_namespace,
1.8 djm 289: struct sshkey **sign_keyp, struct sshkey_sig_details **sig_details)
1.1 djm 290: {
291: int r = SSH_ERR_INTERNAL_ERROR;
292: struct sshbuf *buf = NULL, *toverify = NULL;
293: struct sshkey *key = NULL;
294: const u_char *sig;
295: char *got_namespace = NULL, *sigtype = NULL, *sig_hashalg = NULL;
296: size_t siglen;
297:
1.18 djm 298: debug_f("verify message length %zu", sshbuf_len(h_message));
1.8 djm 299: if (sig_details != NULL)
300: *sig_details = NULL;
1.1 djm 301: if (sign_keyp != NULL)
302: *sign_keyp = NULL;
303:
304: if ((toverify = sshbuf_new()) == NULL) {
1.18 djm 305: error_f("sshbuf_new failed");
1.1 djm 306: r = SSH_ERR_ALLOC_FAIL;
307: goto done;
308: }
309: if ((r = sshbuf_put(toverify, MAGIC_PREAMBLE,
310: MAGIC_PREAMBLE_LEN)) != 0 ||
311: (r = sshbuf_put_cstring(toverify, expect_namespace)) != 0 ||
312: (r = sshbuf_put_string(toverify, NULL, 0)) != 0 || /* reserved */
313: (r = sshbuf_put_cstring(toverify, hashalg)) != 0 ||
1.6 djm 314: (r = sshbuf_put_stringb(toverify, h_message)) != 0) {
1.18 djm 315: error_fr(r, "assemble message to verify");
1.1 djm 316: goto done;
317: }
318:
319: if ((r = sshsig_parse_preamble(signature)) != 0)
320: goto done;
321:
322: if ((r = sshkey_froms(signature, &key)) != 0 ||
323: (r = sshbuf_get_cstring(signature, &got_namespace, NULL)) != 0 ||
324: (r = sshbuf_get_string(signature, NULL, NULL)) != 0 ||
325: (r = sshbuf_get_cstring(signature, &sig_hashalg, NULL)) != 0 ||
326: (r = sshbuf_get_string_direct(signature, &sig, &siglen)) != 0) {
1.18 djm 327: error_fr(r, "parse signature object");
1.1 djm 328: goto done;
329: }
330:
331: if (sshbuf_len(signature) != 0) {
332: error("Signature contains trailing data");
333: r = SSH_ERR_INVALID_FORMAT;
334: goto done;
335: }
336:
337: if (strcmp(expect_namespace, got_namespace) != 0) {
338: error("Couldn't verify signature: namespace does not match");
1.18 djm 339: debug_f("expected namespace \"%s\" received \"%s\"",
340: expect_namespace, got_namespace);
1.1 djm 341: r = SSH_ERR_SIGNATURE_INVALID;
342: goto done;
343: }
344: if (strcmp(hashalg, sig_hashalg) != 0) {
345: error("Couldn't verify signature: hash algorithm mismatch");
1.18 djm 346: debug_f("expected algorithm \"%s\" received \"%s\"",
347: hashalg, sig_hashalg);
1.1 djm 348: r = SSH_ERR_SIGNATURE_INVALID;
349: goto done;
350: }
351: /* Ensure that RSA keys use an acceptable signature algorithm */
352: if (sshkey_type_plain(key->type) == KEY_RSA) {
353: if ((r = sshkey_get_sigtype(sig, siglen, &sigtype)) != 0) {
1.18 djm 354: error_r(r, "Couldn't verify signature: unable to get "
355: "signature type");
1.1 djm 356: goto done;
357: }
358: if (match_pattern_list(sigtype, RSA_SIGN_ALLOWED, 0) != 1) {
359: error("Couldn't verify signature: unsupported RSA "
360: "signature algorithm %s", sigtype);
361: r = SSH_ERR_SIGN_ALG_UNSUPPORTED;
362: goto done;
363: }
364: }
365: if ((r = sshkey_verify(key, sig, siglen, sshbuf_ptr(toverify),
1.8 djm 366: sshbuf_len(toverify), NULL, 0, sig_details)) != 0) {
1.18 djm 367: error_r(r, "Signature verification failed");
1.1 djm 368: goto done;
369: }
370:
371: /* success */
372: r = 0;
373: if (sign_keyp != NULL) {
374: *sign_keyp = key;
375: key = NULL; /* transferred */
376: }
377: done:
378: free(got_namespace);
379: free(sigtype);
380: free(sig_hashalg);
381: sshbuf_free(buf);
382: sshbuf_free(toverify);
383: sshkey_free(key);
384: return r;
385: }
386:
1.2 djm 387: static int
388: hash_buffer(const struct sshbuf *m, const char *hashalg, struct sshbuf **bp)
1.1 djm 389: {
1.2 djm 390: char *hex, hash[SSH_DIGEST_MAX_LENGTH];
391: int alg, r = SSH_ERR_INTERNAL_ERROR;
1.1 djm 392: struct sshbuf *b = NULL;
393:
1.2 djm 394: *bp = NULL;
395: memset(hash, 0, sizeof(hash));
1.1 djm 396:
397: if ((r = sshsig_check_hashalg(hashalg)) != 0)
398: return r;
399: if ((alg = ssh_digest_alg_by_name(hashalg)) == -1) {
1.18 djm 400: error_f("can't look up hash algorithm %s", hashalg);
1.1 djm 401: return SSH_ERR_INTERNAL_ERROR;
402: }
1.2 djm 403: if ((r = ssh_digest_buffer(alg, m, hash, sizeof(hash))) != 0) {
1.18 djm 404: error_fr(r, "ssh_digest_buffer");
1.1 djm 405: return r;
406: }
1.2 djm 407: if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
1.18 djm 408: debug3_f("final hash: %s", hex);
1.2 djm 409: freezero(hex, strlen(hex));
410: }
411: if ((b = sshbuf_new()) == NULL) {
1.1 djm 412: r = SSH_ERR_ALLOC_FAIL;
413: goto out;
414: }
1.2 djm 415: if ((r = sshbuf_put(b, hash, ssh_digest_bytes(alg))) != 0) {
1.18 djm 416: error_fr(r, "sshbuf_put");
1.2 djm 417: goto out;
418: }
419: *bp = b;
420: b = NULL; /* transferred */
421: /* success */
422: r = 0;
423: out:
424: sshbuf_free(b);
425: explicit_bzero(hash, sizeof(hash));
1.12 markus 426: return r;
1.2 djm 427: }
428:
429: int
1.16 djm 430: sshsig_signb(struct sshkey *key, const char *hashalg,
431: const char *sk_provider, const char *sk_pin,
1.2 djm 432: const struct sshbuf *message, const char *sig_namespace,
433: struct sshbuf **out, sshsig_signer *signer, void *signer_ctx)
434: {
435: struct sshbuf *b = NULL;
436: int r = SSH_ERR_INTERNAL_ERROR;
437:
438: if (hashalg == NULL)
439: hashalg = HASHALG_DEFAULT;
440: if (out != NULL)
441: *out = NULL;
442: if ((r = hash_buffer(message, hashalg, &b)) != 0) {
1.18 djm 443: error_fr(r, "hash buffer");
1.2 djm 444: goto out;
445: }
1.16 djm 446: if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
1.7 djm 447: sig_namespace, out, signer, signer_ctx)) != 0)
1.1 djm 448: goto out;
449: /* success */
450: r = 0;
451: out:
452: sshbuf_free(b);
453: return r;
454: }
455:
456: int
1.2 djm 457: sshsig_verifyb(struct sshbuf *signature, const struct sshbuf *message,
1.8 djm 458: const char *expect_namespace, struct sshkey **sign_keyp,
459: struct sshkey_sig_details **sig_details)
1.1 djm 460: {
461: struct sshbuf *b = NULL;
1.2 djm 462: int r = SSH_ERR_INTERNAL_ERROR;
1.1 djm 463: char *hashalg = NULL;
464:
1.8 djm 465: if (sig_details != NULL)
466: *sig_details = NULL;
1.1 djm 467: if (sign_keyp != NULL)
468: *sign_keyp = NULL;
469: if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
470: return r;
1.18 djm 471: debug_f("signature made with hash \"%s\"", hashalg);
1.2 djm 472: if ((r = hash_buffer(message, hashalg, &b)) != 0) {
1.18 djm 473: error_fr(r, "hash buffer");
1.1 djm 474: goto out;
475: }
476: if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
1.8 djm 477: sign_keyp, sig_details)) != 0)
1.1 djm 478: goto out;
479: /* success */
480: r = 0;
481: out:
482: sshbuf_free(b);
483: free(hashalg);
484: return r;
485: }
486:
487: static int
1.2 djm 488: hash_file(int fd, const char *hashalg, struct sshbuf **bp)
1.1 djm 489: {
1.2 djm 490: char *hex, rbuf[8192], hash[SSH_DIGEST_MAX_LENGTH];
1.1 djm 491: ssize_t n, total = 0;
492: struct ssh_digest_ctx *ctx;
1.2 djm 493: int alg, oerrno, r = SSH_ERR_INTERNAL_ERROR;
494: struct sshbuf *b = NULL;
495:
496: *bp = NULL;
497: memset(hash, 0, sizeof(hash));
1.1 djm 498:
1.2 djm 499: if ((r = sshsig_check_hashalg(hashalg)) != 0)
500: return r;
501: if ((alg = ssh_digest_alg_by_name(hashalg)) == -1) {
1.18 djm 502: error_f("can't look up hash algorithm %s", hashalg);
1.2 djm 503: return SSH_ERR_INTERNAL_ERROR;
504: }
505: if ((ctx = ssh_digest_start(alg)) == NULL) {
1.18 djm 506: error_f("ssh_digest_start failed");
1.1 djm 507: return SSH_ERR_INTERNAL_ERROR;
508: }
509: for (;;) {
510: if ((n = read(fd, rbuf, sizeof(rbuf))) == -1) {
511: if (errno == EINTR || errno == EAGAIN)
512: continue;
513: oerrno = errno;
1.18 djm 514: error_f("read: %s", strerror(errno));
1.1 djm 515: ssh_digest_free(ctx);
516: errno = oerrno;
1.2 djm 517: r = SSH_ERR_SYSTEM_ERROR;
518: goto out;
1.1 djm 519: } else if (n == 0) {
1.18 djm 520: debug2_f("hashed %zu bytes", total);
1.1 djm 521: break; /* EOF */
522: }
523: total += (size_t)n;
524: if ((r = ssh_digest_update(ctx, rbuf, (size_t)n)) != 0) {
1.18 djm 525: error_fr(r, "ssh_digest_update");
1.2 djm 526: goto out;
1.1 djm 527: }
528: }
1.2 djm 529: if ((r = ssh_digest_final(ctx, hash, sizeof(hash))) != 0) {
1.18 djm 530: error_fr(r, "ssh_digest_final");
1.2 djm 531: goto out;
1.1 djm 532: }
1.2 djm 533: if ((hex = tohex(hash, ssh_digest_bytes(alg))) != NULL) {
1.18 djm 534: debug3_f("final hash: %s", hex);
1.1 djm 535: freezero(hex, strlen(hex));
536: }
1.2 djm 537: if ((b = sshbuf_new()) == NULL) {
538: r = SSH_ERR_ALLOC_FAIL;
539: goto out;
540: }
541: if ((r = sshbuf_put(b, hash, ssh_digest_bytes(alg))) != 0) {
1.18 djm 542: error_fr(r, "sshbuf_put");
1.2 djm 543: goto out;
544: }
545: *bp = b;
546: b = NULL; /* transferred */
1.1 djm 547: /* success */
1.2 djm 548: r = 0;
549: out:
550: sshbuf_free(b);
1.1 djm 551: ssh_digest_free(ctx);
1.2 djm 552: explicit_bzero(hash, sizeof(hash));
1.12 markus 553: return r;
1.1 djm 554: }
555:
556: int
1.16 djm 557: sshsig_sign_fd(struct sshkey *key, const char *hashalg,
558: const char *sk_provider, const char *sk_pin,
1.1 djm 559: int fd, const char *sig_namespace, struct sshbuf **out,
560: sshsig_signer *signer, void *signer_ctx)
561: {
562: struct sshbuf *b = NULL;
1.2 djm 563: int r = SSH_ERR_INTERNAL_ERROR;
1.1 djm 564:
1.2 djm 565: if (hashalg == NULL)
566: hashalg = HASHALG_DEFAULT;
1.1 djm 567: if (out != NULL)
568: *out = NULL;
1.2 djm 569: if ((r = hash_file(fd, hashalg, &b)) != 0) {
1.18 djm 570: error_fr(r, "hash_file");
1.1 djm 571: return r;
572: }
1.16 djm 573: if ((r = sshsig_wrap_sign(key, hashalg, sk_provider, sk_pin, b,
1.7 djm 574: sig_namespace, out, signer, signer_ctx)) != 0)
1.1 djm 575: goto out;
576: /* success */
577: r = 0;
578: out:
579: sshbuf_free(b);
580: return r;
581: }
582:
583: int
584: sshsig_verify_fd(struct sshbuf *signature, int fd,
1.8 djm 585: const char *expect_namespace, struct sshkey **sign_keyp,
586: struct sshkey_sig_details **sig_details)
1.1 djm 587: {
588: struct sshbuf *b = NULL;
1.2 djm 589: int r = SSH_ERR_INTERNAL_ERROR;
1.1 djm 590: char *hashalg = NULL;
591:
1.8 djm 592: if (sig_details != NULL)
593: *sig_details = NULL;
1.1 djm 594: if (sign_keyp != NULL)
595: *sign_keyp = NULL;
596: if ((r = sshsig_peek_hashalg(signature, &hashalg)) != 0)
597: return r;
1.18 djm 598: debug_f("signature made with hash \"%s\"", hashalg);
1.2 djm 599: if ((r = hash_file(fd, hashalg, &b)) != 0) {
1.18 djm 600: error_fr(r, "hash_file");
1.1 djm 601: goto out;
602: }
603: if ((r = sshsig_wrap_verify(signature, hashalg, b, expect_namespace,
1.8 djm 604: sign_keyp, sig_details)) != 0)
1.1 djm 605: goto out;
606: /* success */
607: r = 0;
608: out:
609: sshbuf_free(b);
610: free(hashalg);
611: return r;
612: }
613:
1.4 djm 614: struct sshsigopt {
1.1 djm 615: int ca;
616: char *namespaces;
617: };
618:
1.4 djm 619: struct sshsigopt *
620: sshsigopt_parse(const char *opts, const char *path, u_long linenum,
1.1 djm 621: const char **errstrp)
622: {
1.4 djm 623: struct sshsigopt *ret;
1.1 djm 624: int r;
625: const char *errstr = NULL;
626:
627: if ((ret = calloc(1, sizeof(*ret))) == NULL)
628: return NULL;
629: if (opts == NULL || *opts == '\0')
630: return ret; /* Empty options yields empty options :) */
631:
632: while (*opts && *opts != ' ' && *opts != '\t') {
633: /* flag options */
634: if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
635: ret->ca = 1;
636: } else if (opt_match(&opts, "namespaces")) {
637: if (ret->namespaces != NULL) {
638: errstr = "multiple \"namespaces\" clauses";
639: goto fail;
640: }
641: ret->namespaces = opt_dequote(&opts, &errstr);
642: if (ret->namespaces == NULL)
643: goto fail;
644: }
645: /*
646: * Skip the comma, and move to the next option
647: * (or break out if there are no more).
648: */
649: if (*opts == '\0' || *opts == ' ' || *opts == '\t')
650: break; /* End of options. */
651: /* Anything other than a comma is an unknown option */
652: if (*opts != ',') {
653: errstr = "unknown key option";
654: goto fail;
655: }
656: opts++;
657: if (*opts == '\0') {
658: errstr = "unexpected end-of-options";
659: goto fail;
660: }
661: }
662: /* success */
663: return ret;
664: fail:
665: if (errstrp != NULL)
666: *errstrp = errstr;
1.5 djm 667: sshsigopt_free(ret);
1.1 djm 668: return NULL;
669: }
670:
1.4 djm 671: void
672: sshsigopt_free(struct sshsigopt *opts)
1.1 djm 673: {
674: if (opts == NULL)
675: return;
676: free(opts->namespaces);
677: free(opts);
678: }
679:
680: static int
1.9 djm 681: parse_principals_key_and_options(const char *path, u_long linenum, char *line,
682: const char *required_principal, char **principalsp, struct sshkey **keyp,
683: struct sshsigopt **sigoptsp)
1.1 djm 684: {
1.9 djm 685: char *opts = NULL, *tmp, *cp, *principals = NULL;
1.1 djm 686: const char *reason = NULL;
1.4 djm 687: struct sshsigopt *sigopts = NULL;
1.9 djm 688: struct sshkey *key = NULL;
689: int r = SSH_ERR_INTERNAL_ERROR;
1.1 djm 690:
1.9 djm 691: if (principalsp != NULL)
692: *principalsp = NULL;
693: if (sigoptsp != NULL)
694: *sigoptsp = NULL;
695: if (keyp != NULL)
696: *keyp = NULL;
1.1 djm 697:
698: cp = line;
699: cp = cp + strspn(cp, " \t"); /* skip leading whitespace */
700: if (*cp == '#' || *cp == '\0')
1.9 djm 701: return SSH_ERR_KEY_NOT_FOUND; /* blank or all-comment line */
702:
703: /* format: identity[,identity...] [option[,option...]] key */
704: if ((tmp = strdelimw(&cp)) == NULL) {
1.1 djm 705: error("%s:%lu: invalid line", path, linenum);
1.9 djm 706: r = SSH_ERR_INVALID_FORMAT;
707: goto out;
1.1 djm 708: }
1.9 djm 709: if ((principals = strdup(tmp)) == NULL) {
1.18 djm 710: error_f("strdup failed");
1.9 djm 711: r = SSH_ERR_ALLOC_FAIL;
712: goto out;
713: }
714: /*
715: * Bail out early if we're looking for a particular principal and this
716: * line does not list it.
717: */
718: if (required_principal != NULL) {
719: if (match_pattern_list(required_principal,
720: principals, 0) != 1) {
721: /* principal didn't match */
722: r = SSH_ERR_KEY_NOT_FOUND;
723: goto out;
724: }
1.18 djm 725: debug_f("%s:%lu: matched principal \"%s\"",
726: path, linenum, required_principal);
1.1 djm 727: }
728:
1.9 djm 729: if ((key = sshkey_new(KEY_UNSPEC)) == NULL) {
1.18 djm 730: error_f("sshkey_new failed");
1.9 djm 731: r = SSH_ERR_ALLOC_FAIL;
732: goto out;
733: }
734: if (sshkey_read(key, &cp) != 0) {
1.1 djm 735: /* no key? Check for options */
736: opts = cp;
737: if (sshkey_advance_past_options(&cp) != 0) {
1.9 djm 738: error("%s:%lu: invalid options", path, linenum);
739: r = SSH_ERR_INVALID_FORMAT;
740: goto out;
1.1 djm 741: }
742: *cp++ = '\0';
743: skip_space(&cp);
1.9 djm 744: if (sshkey_read(key, &cp) != 0) {
745: error("%s:%lu: invalid key", path, linenum);
746: r = SSH_ERR_INVALID_FORMAT;
747: goto out;
1.1 djm 748: }
749: }
750: debug3("%s:%lu: options %s", path, linenum, opts == NULL ? "" : opts);
1.4 djm 751: if ((sigopts = sshsigopt_parse(opts, path, linenum, &reason)) == NULL) {
1.1 djm 752: error("%s:%lu: bad options: %s", path, linenum, reason);
1.9 djm 753: r = SSH_ERR_INVALID_FORMAT;
754: goto out;
755: }
756: /* success */
757: if (principalsp != NULL) {
758: *principalsp = principals;
759: principals = NULL; /* transferred */
760: }
761: if (sigoptsp != NULL) {
762: *sigoptsp = sigopts;
763: sigopts = NULL; /* transferred */
764: }
765: if (keyp != NULL) {
766: *keyp = key;
767: key = NULL; /* transferred */
768: }
769: r = 0;
770: out:
771: free(principals);
772: sshsigopt_free(sigopts);
773: sshkey_free(key);
774: return r;
775: }
776:
777: static int
778: check_allowed_keys_line(const char *path, u_long linenum, char *line,
779: const struct sshkey *sign_key, const char *principal,
780: const char *sig_namespace)
781: {
782: struct sshkey *found_key = NULL;
783: int r, found = 0;
784: const char *reason = NULL;
785: struct sshsigopt *sigopts = NULL;
786:
787: /* Parse the line */
788: if ((r = parse_principals_key_and_options(path, linenum, line,
789: principal, NULL, &found_key, &sigopts)) != 0) {
790: /* error already logged */
1.1 djm 791: goto done;
792: }
793:
794: /* Check whether options preclude the use of this key */
795: if (sigopts->namespaces != NULL &&
796: match_pattern_list(sig_namespace, sigopts->namespaces, 0) != 1) {
797: error("%s:%lu: key is not permitted for use in signature "
798: "namespace \"%s\"", path, linenum, sig_namespace);
799: goto done;
800: }
801:
802: if (!sigopts->ca && sshkey_equal(found_key, sign_key)) {
803: /* Exact match of key */
804: debug("%s:%lu: matched key and principal", path, linenum);
805: /* success */
806: found = 1;
807: } else if (sigopts->ca && sshkey_is_cert(sign_key) &&
808: sshkey_equal_public(sign_key->cert->signature_key, found_key)) {
809: /* Match of certificate's CA key */
1.19 ! djm 810: if ((r = sshkey_cert_check_authority(sign_key, 0, 1, 0,
1.1 djm 811: principal, &reason)) != 0) {
812: error("%s:%lu: certificate not authorized: %s",
813: path, linenum, reason);
814: goto done;
815: }
816: debug("%s:%lu: matched certificate CA key", path, linenum);
817: /* success */
818: found = 1;
819: } else {
820: /* Principal matched but key didn't */
821: goto done;
822: }
823: done:
824: sshkey_free(found_key);
1.4 djm 825: sshsigopt_free(sigopts);
1.1 djm 826: return found ? 0 : SSH_ERR_KEY_NOT_FOUND;
827: }
828:
829: int
830: sshsig_check_allowed_keys(const char *path, const struct sshkey *sign_key,
831: const char *principal, const char *sig_namespace)
832: {
833: FILE *f = NULL;
834: char *line = NULL;
835: size_t linesize = 0;
836: u_long linenum = 0;
1.12 markus 837: int r = SSH_ERR_INTERNAL_ERROR, oerrno;
1.1 djm 838:
839: /* Check key and principal against file */
840: if ((f = fopen(path, "r")) == NULL) {
841: oerrno = errno;
842: error("Unable to open allowed keys file \"%s\": %s",
843: path, strerror(errno));
844: errno = oerrno;
845: return SSH_ERR_SYSTEM_ERROR;
846: }
847:
848: while (getline(&line, &linesize, f) != -1) {
849: linenum++;
850: r = check_allowed_keys_line(path, linenum, line, sign_key,
851: principal, sig_namespace);
1.2 djm 852: free(line);
853: line = NULL;
1.1 djm 854: if (r == SSH_ERR_KEY_NOT_FOUND)
855: continue;
856: else if (r == 0) {
857: /* success */
858: fclose(f);
859: return 0;
860: } else
861: break;
862: }
863: /* Either we hit an error parsing or we simply didn't find the key */
864: fclose(f);
865: free(line);
866: return r == 0 ? SSH_ERR_KEY_NOT_FOUND : r;
867: }
1.10 djm 868:
869: static int
1.11 djm 870: cert_filter_principals(const char *path, u_long linenum,
871: char **principalsp, const struct sshkey *cert)
872: {
873: char *cp, *oprincipals, *principals;
874: const char *reason;
875: struct sshbuf *nprincipals;
876: int r = SSH_ERR_INTERNAL_ERROR, success = 0;
877:
878: oprincipals = principals = *principalsp;
879: *principalsp = NULL;
880:
1.15 markus 881: if ((nprincipals = sshbuf_new()) == NULL) {
882: r = SSH_ERR_ALLOC_FAIL;
883: goto out;
884: }
1.11 djm 885:
886: while ((cp = strsep(&principals, ",")) != NULL && *cp != '\0') {
887: if (strcspn(cp, "!?*") != strlen(cp)) {
888: debug("%s:%lu: principal \"%s\" not authorized: "
889: "contains wildcards", path, linenum, cp);
890: continue;
891: }
892: /* Check against principals list in certificate */
1.19 ! djm 893: if ((r = sshkey_cert_check_authority(cert, 0, 1, 0,
1.11 djm 894: cp, &reason)) != 0) {
895: debug("%s:%lu: principal \"%s\" not authorized: %s",
896: path, linenum, cp, reason);
897: continue;
898: }
899: if ((r = sshbuf_putf(nprincipals, "%s%s",
900: sshbuf_len(nprincipals) != 0 ? "," : "", cp)) != 0) {
1.18 djm 901: error_f("buffer error");
1.11 djm 902: goto out;
903: }
904: }
905: if (sshbuf_len(nprincipals) == 0) {
906: error("%s:%lu: no valid principals found", path, linenum);
907: r = SSH_ERR_KEY_CERT_INVALID;
908: goto out;
909: }
910: if ((principals = sshbuf_dup_string(nprincipals)) == NULL) {
1.18 djm 911: error_f("buffer error");
1.11 djm 912: goto out;
913: }
914: /* success */
915: success = 1;
916: *principalsp = principals;
917: out:
918: sshbuf_free(nprincipals);
919: free(oprincipals);
920: return success ? 0 : r;
921: }
922:
923: static int
924: get_matching_principals_from_line(const char *path, u_long linenum, char *line,
1.10 djm 925: const struct sshkey *sign_key, char **principalsp)
926: {
927: struct sshkey *found_key = NULL;
928: char *principals = NULL;
929: int r, found = 0;
930: struct sshsigopt *sigopts = NULL;
931:
932: if (principalsp != NULL)
933: *principalsp = NULL;
934:
935: /* Parse the line */
936: if ((r = parse_principals_key_and_options(path, linenum, line,
937: NULL, &principals, &found_key, &sigopts)) != 0) {
938: /* error already logged */
939: goto done;
940: }
941:
942: if (!sigopts->ca && sshkey_equal(found_key, sign_key)) {
943: /* Exact match of key */
944: debug("%s:%lu: matched key", path, linenum);
945: /* success */
946: found = 1;
947: } else if (sigopts->ca && sshkey_is_cert(sign_key) &&
948: sshkey_equal_public(sign_key->cert->signature_key, found_key)) {
1.11 djm 949: /* Remove principals listed in file but not allowed by cert */
950: if ((r = cert_filter_principals(path, linenum,
951: &principals, sign_key)) != 0) {
952: /* error already displayed */
1.18 djm 953: debug_r(r, "%s:%lu: cert_filter_principals",
954: path, linenum);
1.10 djm 955: goto done;
956: }
957: debug("%s:%lu: matched certificate CA key", path, linenum);
958: /* success */
959: found = 1;
960: } else {
961: /* Key didn't match */
962: goto done;
963: }
964: done:
1.13 markus 965: if (found && principalsp != NULL) {
1.10 djm 966: *principalsp = principals;
967: principals = NULL; /* transferred */
968: }
969: free(principals);
970: sshkey_free(found_key);
971: sshsigopt_free(sigopts);
972: return found ? 0 : SSH_ERR_KEY_NOT_FOUND;
973: }
974:
975: int
1.11 djm 976: sshsig_find_principals(const char *path, const struct sshkey *sign_key,
977: char **principals)
1.10 djm 978: {
979: FILE *f = NULL;
980: char *line = NULL;
981: size_t linesize = 0;
982: u_long linenum = 0;
1.14 markus 983: int r = SSH_ERR_INTERNAL_ERROR, oerrno;
1.10 djm 984:
985: if ((f = fopen(path, "r")) == NULL) {
986: oerrno = errno;
987: error("Unable to open allowed keys file \"%s\": %s",
988: path, strerror(errno));
989: errno = oerrno;
990: return SSH_ERR_SYSTEM_ERROR;
991: }
992:
993: while (getline(&line, &linesize, f) != -1) {
994: linenum++;
1.11 djm 995: r = get_matching_principals_from_line(path, linenum, line,
996: sign_key, principals);
1.10 djm 997: free(line);
998: line = NULL;
999: if (r == SSH_ERR_KEY_NOT_FOUND)
1000: continue;
1001: else if (r == 0) {
1002: /* success */
1003: fclose(f);
1004: return 0;
1005: } else
1006: break;
1007: }
1008: free(line);
1009: /* Either we hit an error parsing or we simply didn't find the key */
1010: if (ferror(f) != 0) {
1011: oerrno = errno;
1012: fclose(f);
1013: error("Unable to read allowed keys file \"%s\": %s",
1014: path, strerror(errno));
1015: errno = oerrno;
1016: return SSH_ERR_SYSTEM_ERROR;
1017: }
1018: fclose(f);
1019: return r == 0 ? SSH_ERR_KEY_NOT_FOUND : r;
1020: }
1021:
1022: int
1023: sshsig_get_pubkey(struct sshbuf *signature, struct sshkey **pubkey)
1024: {
1025: struct sshkey *pk = NULL;
1026: int r = SSH_ERR_SIGNATURE_INVALID;
1027:
1.13 markus 1028: if (pubkey == NULL)
1029: return SSH_ERR_INTERNAL_ERROR;
1.10 djm 1030: if ((r = sshsig_parse_preamble(signature)) != 0)
1031: return r;
1032: if ((r = sshkey_froms(signature, &pk)) != 0)
1033: return r;
1034:
1035: *pubkey = pk;
1036: pk = NULL;
1037: return 0;
1038: }
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