1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
|
From 7c6fb56c3bcafa96c0bc87350f0f9e85f002a254 Mon Sep 17 00:00:00 2001
From: Dennis Jackson <djackson@mozilla.com>
Date: Mon, 22 Nov 2021 10:40:42 +0000
Subject: [PATCH] Bug 1737470 - Ensure DER encoded signatures are within size
limits. r=jschanck,mt,bbeurdouche,rrelyea
Differential Revision: https://phabricator.services.mozilla.com/D129514
--HG--
branch : NSS_3_68_1_BRANCH
Upstream-Status: Backport [7c6fb56c3bcafa96c0bc87350f0f9e85f002a254]
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
lib/cryptohi/secvfy.c | 192 ++++++++++++++++++++++++++----------------
1 file changed, 121 insertions(+), 71 deletions(-)
diff --git a/nss/lib/cryptohi/secvfy.c b/nss/lib/cryptohi/secvfy.c
index 2540a544c..17545848c 100644
--- a/nss/lib/cryptohi/secvfy.c
+++ b/nss/lib/cryptohi/secvfy.c
@@ -164,6 +164,37 @@ verifyPKCS1DigestInfo(const VFYContext *cx, const SECItem *digest)
PR_FALSE /*XXX: unsafeAllowMissingParameters*/);
}
+static unsigned int
+checkedSignatureLen(const SECKEYPublicKey *pubk)
+{
+ unsigned int sigLen = SECKEY_SignatureLen(pubk);
+ if (sigLen == 0) {
+ /* Error set by SECKEY_SignatureLen */
+ return sigLen;
+ }
+ unsigned int maxSigLen;
+ switch (pubk->keyType) {
+ case rsaKey:
+ case rsaPssKey:
+ maxSigLen = (RSA_MAX_MODULUS_BITS + 7) / 8;
+ break;
+ case dsaKey:
+ maxSigLen = DSA_MAX_SIGNATURE_LEN;
+ break;
+ case ecKey:
+ maxSigLen = 2 * MAX_ECKEY_LEN;
+ break;
+ default:
+ PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
+ return 0;
+ }
+ if (sigLen > maxSigLen) {
+ PORT_SetError(SEC_ERROR_INVALID_KEY);
+ return 0;
+ }
+ return sigLen;
+}
+
/*
* decode the ECDSA or DSA signature from it's DER wrapping.
* The unwrapped/raw signature is placed in the buffer pointed
@@ -174,38 +205,38 @@ decodeECorDSASignature(SECOidTag algid, const SECItem *sig, unsigned char *dsig,
unsigned int len)
{
SECItem *dsasig = NULL; /* also used for ECDSA */
- SECStatus rv = SECSuccess;
- if ((algid != SEC_OID_ANSIX9_DSA_SIGNATURE) &&
- (algid != SEC_OID_ANSIX962_EC_PUBLIC_KEY)) {
- if (sig->len != len) {
- PORT_SetError(SEC_ERROR_BAD_DER);
- return SECFailure;
+ /* Safety: Ensure algId is as expected and that signature size is within maxmimums */
+ if (algid == SEC_OID_ANSIX9_DSA_SIGNATURE) {
+ if (len > DSA_MAX_SIGNATURE_LEN) {
+ goto loser;
}
-
- PORT_Memcpy(dsig, sig->data, sig->len);
- return SECSuccess;
- }
-
- if (algid == SEC_OID_ANSIX962_EC_PUBLIC_KEY) {
+ } else if (algid == SEC_OID_ANSIX962_EC_PUBLIC_KEY) {
if (len > MAX_ECKEY_LEN * 2) {
- PORT_SetError(SEC_ERROR_BAD_DER);
- return SECFailure;
+ goto loser;
}
- }
- dsasig = DSAU_DecodeDerSigToLen((SECItem *)sig, len);
-
- if ((dsasig == NULL) || (dsasig->len != len)) {
- rv = SECFailure;
} else {
- PORT_Memcpy(dsig, dsasig->data, dsasig->len);
+ goto loser;
}
- if (dsasig != NULL)
+ /* Decode and pad to length */
+ dsasig = DSAU_DecodeDerSigToLen((SECItem *)sig, len);
+ if (dsasig == NULL) {
+ goto loser;
+ }
+ if (dsasig->len != len) {
SECITEM_FreeItem(dsasig, PR_TRUE);
- if (rv == SECFailure)
- PORT_SetError(SEC_ERROR_BAD_DER);
- return rv;
+ goto loser;
+ }
+
+ PORT_Memcpy(dsig, dsasig->data, len);
+ SECITEM_FreeItem(dsasig, PR_TRUE);
+
+ return SECSuccess;
+
+loser:
+ PORT_SetError(SEC_ERROR_BAD_DER);
+ return SECFailure;
}
const SEC_ASN1Template hashParameterTemplate[] =
@@ -281,7 +312,7 @@ SECStatus
sec_DecodeSigAlg(const SECKEYPublicKey *key, SECOidTag sigAlg,
const SECItem *param, SECOidTag *encalgp, SECOidTag *hashalg)
{
- int len;
+ unsigned int len;
PLArenaPool *arena;
SECStatus rv;
SECItem oid;
@@ -466,48 +497,52 @@ vfy_CreateContext(const SECKEYPublicKey *key, const SECItem *sig,
cx->pkcs1RSADigestInfo = NULL;
rv = SECSuccess;
if (sig) {
- switch (type) {
- case rsaKey:
- rv = recoverPKCS1DigestInfo(hashAlg, &cx->hashAlg,
- &cx->pkcs1RSADigestInfo,
- &cx->pkcs1RSADigestInfoLen,
- cx->key,
- sig, wincx);
- break;
- case rsaPssKey:
- sigLen = SECKEY_SignatureLen(key);
- if (sigLen == 0) {
- /* error set by SECKEY_SignatureLen */
- rv = SECFailure;
+ rv = SECFailure;
+ if (type == rsaKey) {
+ rv = recoverPKCS1DigestInfo(hashAlg, &cx->hashAlg,
+ &cx->pkcs1RSADigestInfo,
+ &cx->pkcs1RSADigestInfoLen,
+ cx->key,
+ sig, wincx);
+ } else {
+ sigLen = checkedSignatureLen(key);
+ /* Check signature length is within limits */
+ if (sigLen == 0) {
+ /* error set by checkedSignatureLen */
+ rv = SECFailure;
+ goto loser;
+ }
+ if (sigLen > sizeof(cx->u)) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+ rv = SECFailure;
+ goto loser;
+ }
+ switch (type) {
+ case rsaPssKey:
+ if (sig->len != sigLen) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+ rv = SECFailure;
+ goto loser;
+ }
+ PORT_Memcpy(cx->u.buffer, sig->data, sigLen);
+ rv = SECSuccess;
break;
- }
- if (sig->len != sigLen) {
- PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
- rv = SECFailure;
+ case ecKey:
+ case dsaKey:
+ /* decodeECorDSASignature will check sigLen == sig->len after padding */
+ rv = decodeECorDSASignature(encAlg, sig, cx->u.buffer, sigLen);
break;
- }
- PORT_Memcpy(cx->u.buffer, sig->data, sigLen);
- break;
- case dsaKey:
- case ecKey:
- sigLen = SECKEY_SignatureLen(key);
- if (sigLen == 0) {
- /* error set by SECKEY_SignatureLen */
+ default:
+ /* Unreachable */
rv = SECFailure;
- break;
- }
- rv = decodeECorDSASignature(encAlg, sig, cx->u.buffer, sigLen);
- break;
- default:
- rv = SECFailure;
- PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
- break;
+ goto loser;
+ }
+ }
+ if (rv != SECSuccess) {
+ goto loser;
}
}
- if (rv)
- goto loser;
-
/* check hash alg again, RSA may have changed it.*/
if (HASH_GetHashTypeByOidTag(cx->hashAlg) == HASH_AlgNULL) {
/* error set by HASH_GetHashTypeByOidTag */
@@ -650,11 +685,16 @@ VFY_EndWithSignature(VFYContext *cx, SECItem *sig)
switch (cx->key->keyType) {
case ecKey:
case dsaKey:
- dsasig.data = cx->u.buffer;
- dsasig.len = SECKEY_SignatureLen(cx->key);
+ dsasig.len = checkedSignatureLen(cx->key);
if (dsasig.len == 0) {
return SECFailure;
}
+ if (dsasig.len > sizeof(cx->u)) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+ return SECFailure;
+ }
+ dsasig.data = cx->u.buffer;
+
if (sig) {
rv = decodeECorDSASignature(cx->encAlg, sig, dsasig.data,
dsasig.len);
@@ -686,8 +726,13 @@ VFY_EndWithSignature(VFYContext *cx, SECItem *sig)
}
rsasig.data = cx->u.buffer;
- rsasig.len = SECKEY_SignatureLen(cx->key);
+ rsasig.len = checkedSignatureLen(cx->key);
if (rsasig.len == 0) {
+ /* Error set by checkedSignatureLen */
+ return SECFailure;
+ }
+ if (rsasig.len > sizeof(cx->u)) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
return SECFailure;
}
if (sig) {
@@ -749,7 +794,6 @@ vfy_VerifyDigest(const SECItem *digest, const SECKEYPublicKey *key,
SECStatus rv;
VFYContext *cx;
SECItem dsasig; /* also used for ECDSA */
-
rv = SECFailure;
cx = vfy_CreateContext(key, sig, encAlg, hashAlg, NULL, wincx);
@@ -757,19 +801,25 @@ vfy_VerifyDigest(const SECItem *digest, const SECKEYPublicKey *key,
switch (key->keyType) {
case rsaKey:
rv = verifyPKCS1DigestInfo(cx, digest);
+ /* Error (if any) set by verifyPKCS1DigestInfo */
break;
- case dsaKey:
case ecKey:
+ case dsaKey:
dsasig.data = cx->u.buffer;
- dsasig.len = SECKEY_SignatureLen(cx->key);
+ dsasig.len = checkedSignatureLen(cx->key);
if (dsasig.len == 0) {
+ /* Error set by checkedSignatureLen */
+ rv = SECFailure;
break;
}
- if (PK11_Verify(cx->key, &dsasig, (SECItem *)digest, cx->wincx) !=
- SECSuccess) {
+ if (dsasig.len > sizeof(cx->u)) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+ rv = SECFailure;
+ break;
+ }
+ rv = PK11_Verify(cx->key, &dsasig, (SECItem *)digest, cx->wincx);
+ if (rv != SECSuccess) {
PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
- } else {
- rv = SECSuccess;
}
break;
default:
--
2.25.1
|
