Bug Summary

File:src/usr.bin/ssh/ssh-pkcs11-helper/../ssh-rsa.c
Warning:line 406, column 2
Value stored to 'ret' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ssh-rsa.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/usr.bin/ssh/ssh-pkcs11-helper/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/usr.bin/ssh/ssh-pkcs11-helper/.. -D WITH_OPENSSL -D WITH_ZLIB -D ENABLE_PKCS11 -D HAVE_DLOPEN -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -fdebug-compilation-dir=/usr/src/usr.bin/ssh/ssh-pkcs11-helper/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c /usr/src/usr.bin/ssh/ssh-pkcs11-helper/../ssh-rsa.c
1/* $OpenBSD: ssh-rsa.c,v 1.68 2018/09/13 02:08:33 djm Exp $ */
2/*
3 * Copyright (c) 2000, 2003 Markus Friedl <markus@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#include <sys/types.h>
19
20#include <openssl/evp.h>
21#include <openssl/err.h>
22
23#include <string.h>
24
25#include "sshbuf.h"
26#include "compat.h"
27#include "ssherr.h"
28#define SSHKEY_INTERNAL
29#include "sshkey.h"
30#include "digest.h"
31#include "log.h"
32
33static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);
34
35static const char *
36rsa_hash_alg_ident(int hash_alg)
37{
38 switch (hash_alg) {
39 case SSH_DIGEST_SHA11:
40 return "ssh-rsa";
41 case SSH_DIGEST_SHA2562:
42 return "rsa-sha2-256";
43 case SSH_DIGEST_SHA5124:
44 return "rsa-sha2-512";
45 }
46 return NULL((void *)0);
47}
48
49/*
50 * Returns the hash algorithm ID for a given algorithm identifier as used
51 * inside the signature blob,
52 */
53static int
54rsa_hash_id_from_ident(const char *ident)
55{
56 if (strcmp(ident, "ssh-rsa") == 0)
57 return SSH_DIGEST_SHA11;
58 if (strcmp(ident, "rsa-sha2-256") == 0)
59 return SSH_DIGEST_SHA2562;
60 if (strcmp(ident, "rsa-sha2-512") == 0)
61 return SSH_DIGEST_SHA5124;
62 return -1;
63}
64
65/*
66 * Return the hash algorithm ID for the specified key name. This includes
67 * all the cases of rsa_hash_id_from_ident() but also the certificate key
68 * types.
69 */
70static int
71rsa_hash_id_from_keyname(const char *alg)
72{
73 int r;
74
75 if ((r = rsa_hash_id_from_ident(alg)) != -1)
76 return r;
77 if (strcmp(alg, "ssh-rsa-cert-v01@openssh.com") == 0)
78 return SSH_DIGEST_SHA11;
79 if (strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0)
80 return SSH_DIGEST_SHA2562;
81 if (strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0)
82 return SSH_DIGEST_SHA5124;
83 return -1;
84}
85
86static int
87rsa_hash_alg_nid(int type)
88{
89 switch (type) {
90 case SSH_DIGEST_SHA11:
91 return NID_sha164;
92 case SSH_DIGEST_SHA2562:
93 return NID_sha256672;
94 case SSH_DIGEST_SHA5124:
95 return NID_sha512674;
96 default:
97 return -1;
98 }
99}
100
101int
102ssh_rsa_complete_crt_parameters(struct sshkey *key, const BIGNUM *iqmp)
103{
104 const BIGNUM *rsa_p, *rsa_q, *rsa_d;
105 BIGNUM *aux = NULL((void *)0), *d_consttime = NULL((void *)0);
106 BIGNUM *rsa_dmq1 = NULL((void *)0), *rsa_dmp1 = NULL((void *)0), *rsa_iqmp = NULL((void *)0);
107 BN_CTX *ctx = NULL((void *)0);
108 int r;
109
110 if (key == NULL((void *)0) || key->rsa == NULL((void *)0) ||
111 sshkey_type_plain(key->type) != KEY_RSA)
112 return SSH_ERR_INVALID_ARGUMENT-10;
113
114 RSA_get0_key(key->rsa, NULL((void *)0), NULL((void *)0), &rsa_d);
115 RSA_get0_factors(key->rsa, &rsa_p, &rsa_q);
116
117 if ((ctx = BN_CTX_new()) == NULL((void *)0))
118 return SSH_ERR_ALLOC_FAIL-2;
119 if ((aux = BN_new()) == NULL((void *)0) ||
120 (rsa_dmq1 = BN_new()) == NULL((void *)0) ||
121 (rsa_dmp1 = BN_new()) == NULL((void *)0))
122 return SSH_ERR_ALLOC_FAIL-2;
123 if ((d_consttime = BN_dup(rsa_d)) == NULL((void *)0) ||
124 (rsa_iqmp = BN_dup(iqmp)) == NULL((void *)0)) {
125 r = SSH_ERR_ALLOC_FAIL-2;
126 goto out;
127 }
128 BN_set_flags(aux, BN_FLG_CONSTTIME)((aux)->flags|=(0x04));
129 BN_set_flags(d_consttime, BN_FLG_CONSTTIME)((d_consttime)->flags|=(0x04));
130
131 if ((BN_sub(aux, rsa_q, BN_value_one()) == 0) ||
132 (BN_mod(rsa_dmq1, d_consttime, aux, ctx)BN_div(((void *)0),(rsa_dmq1),(d_consttime),(aux),(ctx)) == 0) ||
133 (BN_sub(aux, rsa_p, BN_value_one()) == 0) ||
134 (BN_mod(rsa_dmp1, d_consttime, aux, ctx)BN_div(((void *)0),(rsa_dmp1),(d_consttime),(aux),(ctx)) == 0)) {
135 r = SSH_ERR_LIBCRYPTO_ERROR-22;
136 goto out;
137 }
138 if (!RSA_set0_crt_params(key->rsa, rsa_dmp1, rsa_dmq1, rsa_iqmp)) {
139 r = SSH_ERR_LIBCRYPTO_ERROR-22;
140 goto out;
141 }
142 rsa_dmp1 = rsa_dmq1 = rsa_iqmp = NULL((void *)0); /* transferred */
143 /* success */
144 r = 0;
145 out:
146 BN_clear_free(aux);
147 BN_clear_free(d_consttime);
148 BN_clear_free(rsa_dmp1);
149 BN_clear_free(rsa_dmq1);
150 BN_clear_free(rsa_iqmp);
151 BN_CTX_free(ctx);
152 return r;
153}
154
155/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
156int
157ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
158 const u_char *data, size_t datalen, const char *alg_ident)
159{
160 const BIGNUM *rsa_n;
161 u_char digest[SSH_DIGEST_MAX_LENGTH64], *sig = NULL((void *)0);
162 size_t slen = 0;
163 u_int dlen, len;
164 int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR-1;
165 struct sshbuf *b = NULL((void *)0);
166
167 if (lenp != NULL((void *)0))
168 *lenp = 0;
169 if (sigp != NULL((void *)0))
170 *sigp = NULL((void *)0);
171
172 if (alg_ident == NULL((void *)0) || strlen(alg_ident) == 0)
173 hash_alg = SSH_DIGEST_SHA11;
174 else
175 hash_alg = rsa_hash_id_from_keyname(alg_ident);
176 if (key == NULL((void *)0) || key->rsa == NULL((void *)0) || hash_alg == -1 ||
177 sshkey_type_plain(key->type) != KEY_RSA)
178 return SSH_ERR_INVALID_ARGUMENT-10;
179 RSA_get0_key(key->rsa, &rsa_n, NULL((void *)0), NULL((void *)0));
180 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE1024)
181 return SSH_ERR_KEY_LENGTH-56;
182 slen = RSA_size(key->rsa);
183 if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM(16384 / 8))
184 return SSH_ERR_INVALID_ARGUMENT-10;
185
186 /* hash the data */
187 nid = rsa_hash_alg_nid(hash_alg);
188 if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
189 return SSH_ERR_INTERNAL_ERROR-1;
190 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
191 digest, sizeof(digest))) != 0)
192 goto out;
193
194 if ((sig = malloc(slen)) == NULL((void *)0)) {
195 ret = SSH_ERR_ALLOC_FAIL-2;
196 goto out;
197 }
198
199 if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
200 ret = SSH_ERR_LIBCRYPTO_ERROR-22;
201 goto out;
202 }
203 if (len < slen) {
204 size_t diff = slen - len;
205 memmove(sig + diff, sig, len);
206 explicit_bzero(sig, diff);
207 } else if (len > slen) {
208 ret = SSH_ERR_INTERNAL_ERROR-1;
209 goto out;
210 }
211 /* encode signature */
212 if ((b = sshbuf_new()) == NULL((void *)0)) {
213 ret = SSH_ERR_ALLOC_FAIL-2;
214 goto out;
215 }
216 if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 ||
217 (ret = sshbuf_put_string(b, sig, slen)) != 0)
218 goto out;
219 len = sshbuf_len(b);
220 if (sigp != NULL((void *)0)) {
221 if ((*sigp = malloc(len)) == NULL((void *)0)) {
222 ret = SSH_ERR_ALLOC_FAIL-2;
223 goto out;
224 }
225 memcpy(*sigp, sshbuf_ptr(b), len);
226 }
227 if (lenp != NULL((void *)0))
228 *lenp = len;
229 ret = 0;
230 out:
231 explicit_bzero(digest, sizeof(digest));
232 freezero(sig, slen);
233 sshbuf_free(b);
234 return ret;
235}
236
237int
238ssh_rsa_verify(const struct sshkey *key,
239 const u_char *sig, size_t siglen, const u_char *data, size_t datalen,
240 const char *alg)
241{
242 const BIGNUM *rsa_n;
243 char *sigtype = NULL((void *)0);
244 int hash_alg, want_alg, ret = SSH_ERR_INTERNAL_ERROR-1;
245 size_t len = 0, diff, modlen, dlen;
246 struct sshbuf *b = NULL((void *)0);
247 u_char digest[SSH_DIGEST_MAX_LENGTH64], *osigblob, *sigblob = NULL((void *)0);
248
249 if (key == NULL((void *)0) || key->rsa == NULL((void *)0) ||
250 sshkey_type_plain(key->type) != KEY_RSA ||
251 sig == NULL((void *)0) || siglen == 0)
252 return SSH_ERR_INVALID_ARGUMENT-10;
253 RSA_get0_key(key->rsa, &rsa_n, NULL((void *)0), NULL((void *)0));
254 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE1024)
255 return SSH_ERR_KEY_LENGTH-56;
256
257 if ((b = sshbuf_from(sig, siglen)) == NULL((void *)0))
258 return SSH_ERR_ALLOC_FAIL-2;
259 if (sshbuf_get_cstring(b, &sigtype, NULL((void *)0)) != 0) {
260 ret = SSH_ERR_INVALID_FORMAT-4;
261 goto out;
262 }
263 if ((hash_alg = rsa_hash_id_from_ident(sigtype)) == -1) {
264 ret = SSH_ERR_KEY_TYPE_MISMATCH-13;
265 goto out;
266 }
267 /*
268 * Allow ssh-rsa-cert-v01 certs to generate SHA2 signatures for
269 * legacy reasons, but otherwise the signature type should match.
270 */
271 if (alg != NULL((void *)0) && strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) {
272 if ((want_alg = rsa_hash_id_from_keyname(alg)) == -1) {
273 ret = SSH_ERR_INVALID_ARGUMENT-10;
274 goto out;
275 }
276 if (hash_alg != want_alg) {
277 ret = SSH_ERR_SIGNATURE_INVALID-21;
278 goto out;
279 }
280 }
281 if (sshbuf_get_string(b, &sigblob, &len) != 0) {
282 ret = SSH_ERR_INVALID_FORMAT-4;
283 goto out;
284 }
285 if (sshbuf_len(b) != 0) {
286 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA-23;
287 goto out;
288 }
289 /* RSA_verify expects a signature of RSA_size */
290 modlen = RSA_size(key->rsa);
291 if (len > modlen) {
292 ret = SSH_ERR_KEY_BITS_MISMATCH-11;
293 goto out;
294 } else if (len < modlen) {
295 diff = modlen - len;
296 osigblob = sigblob;
297 if ((sigblob = realloc(sigblob, modlen)) == NULL((void *)0)) {
298 sigblob = osigblob; /* put it back for clear/free */
299 ret = SSH_ERR_ALLOC_FAIL-2;
300 goto out;
301 }
302 memmove(sigblob + diff, sigblob, len);
303 explicit_bzero(sigblob, diff);
304 len = modlen;
305 }
306 if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
307 ret = SSH_ERR_INTERNAL_ERROR-1;
308 goto out;
309 }
310 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
311 digest, sizeof(digest))) != 0)
312 goto out;
313
314 ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
315 key->rsa);
316 out:
317 freezero(sigblob, len);
318 free(sigtype);
319 sshbuf_free(b);
320 explicit_bzero(digest, sizeof(digest));
321 return ret;
322}
323
324/*
325 * See:
326 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
327 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
328 */
329
330/*
331 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
332 * oiw(14) secsig(3) algorithms(2) 26 }
333 */
334static const u_char id_sha1[] = {
335 0x30, 0x21, /* type Sequence, length 0x21 (33) */
336 0x30, 0x09, /* type Sequence, length 0x09 */
337 0x06, 0x05, /* type OID, length 0x05 */
338 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
339 0x05, 0x00, /* NULL */
340 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */
341};
342
343/*
344 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
345 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
346 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
347 * id-sha256(1) }
348 */
349static const u_char id_sha256[] = {
350 0x30, 0x31, /* type Sequence, length 0x31 (49) */
351 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
352 0x06, 0x09, /* type OID, length 0x09 */
353 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */
354 0x05, 0x00, /* NULL */
355 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */
356};
357
358/*
359 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
360 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
361 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
362 * id-sha256(3) }
363 */
364static const u_char id_sha512[] = {
365 0x30, 0x51, /* type Sequence, length 0x51 (81) */
366 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
367 0x06, 0x09, /* type OID, length 0x09 */
368 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */
369 0x05, 0x00, /* NULL */
370 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */
371};
372
373static int
374rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)
375{
376 switch (hash_alg) {
377 case SSH_DIGEST_SHA11:
378 *oidp = id_sha1;
379 *oidlenp = sizeof(id_sha1);
380 break;
381 case SSH_DIGEST_SHA2562:
382 *oidp = id_sha256;
383 *oidlenp = sizeof(id_sha256);
384 break;
385 case SSH_DIGEST_SHA5124:
386 *oidp = id_sha512;
387 *oidlenp = sizeof(id_sha512);
388 break;
389 default:
390 return SSH_ERR_INVALID_ARGUMENT-10;
391 }
392 return 0;
393}
394
395static int
396openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
397 u_char *sigbuf, size_t siglen, RSA *rsa)
398{
399 size_t rsasize = 0, oidlen = 0, hlen = 0;
400 int ret, len, oidmatch, hashmatch;
401 const u_char *oid = NULL((void *)0);
402 u_char *decrypted = NULL((void *)0);
403
404 if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0)
405 return ret;
406 ret = SSH_ERR_INTERNAL_ERROR-1;
Value stored to 'ret' is never read
407 hlen = ssh_digest_bytes(hash_alg);
408 if (hashlen != hlen) {
409 ret = SSH_ERR_INVALID_ARGUMENT-10;
410 goto done;
411 }
412 rsasize = RSA_size(rsa);
413 if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM(16384 / 8) ||
414 siglen == 0 || siglen > rsasize) {
415 ret = SSH_ERR_INVALID_ARGUMENT-10;
416 goto done;
417 }
418 if ((decrypted = malloc(rsasize)) == NULL((void *)0)) {
419 ret = SSH_ERR_ALLOC_FAIL-2;
420 goto done;
421 }
422 if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
423 RSA_PKCS1_PADDING1)) < 0) {
424 ret = SSH_ERR_LIBCRYPTO_ERROR-22;
425 goto done;
426 }
427 if (len < 0 || (size_t)len != hlen + oidlen) {
428 ret = SSH_ERR_INVALID_FORMAT-4;
429 goto done;
430 }
431 oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
432 hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
433 if (!oidmatch || !hashmatch) {
434 ret = SSH_ERR_SIGNATURE_INVALID-21;
435 goto done;
436 }
437 ret = 0;
438done:
439 freezero(decrypted, rsasize);
440 return ret;
441}