From df11c6cb80238fb43c4a5994161cc2e70521ffb4 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Tue, 18 Aug 2020 10:54:39 +0200
Subject: [PATCH] Fix CVE-2020-8623
5480. [security] When BIND 9 was compiled with native PKCS#11 support, it
was possible to trigger an assertion failure in code
determining the number of bits in the PKCS#11 RSA public
key with a specially crafted packet. (CVE-2020-8623)
[GL #2037]
---
lib/dns/pkcs11dh_link.c | 15 ++++++-
lib/dns/pkcs11dsa_link.c | 8 +++-
lib/dns/pkcs11rsa_link.c | 79 +++++++++++++++++++++++++--------
lib/isc/include/pk11/internal.h | 3 +-
lib/isc/pk11.c | 60 ++++++++++++++++---------
5 files changed, 121 insertions(+), 44 deletions(-)
diff --git a/lib/dns/pkcs11dh_link.c b/lib/dns/pkcs11dh_link.c
index c192b53..49ff58d 100644
--- a/lib/dns/pkcs11dh_link.c
+++ b/lib/dns/pkcs11dh_link.c
@@ -747,6 +747,7 @@ pkcs11dh_fromdns(dst_key_t *key, isc_buffer_t *data) {
CK_BYTE *prime = NULL, *base = NULL, *pub = NULL;
CK_ATTRIBUTE *attr;
int special = 0;
+ unsigned int bits;
isc_result_t result;
isc_buffer_remainingregion(data, &r);
@@ -851,7 +852,11 @@ pkcs11dh_fromdns(dst_key_t *key, isc_buffer_t *data) {
pub = r.base;
isc_region_consume(&r, publen);
- key->key_size = pk11_numbits(prime, plen_);
+ result = pk11_numbits(prime, plen_, &bits);
+ if (result != ISC_R_SUCCESS) {
+ goto cleanup;
+ }
+ key->key_size = bits;
dh->repr = (CK_ATTRIBUTE *) isc_mem_get(key->mctx, sizeof(*attr) * 3);
if (dh->repr == NULL)
@@ -1011,6 +1016,7 @@ pkcs11dh_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
dst_private_t priv;
isc_result_t ret;
int i;
+ unsigned int bits;
pk11_object_t *dh = NULL;
CK_ATTRIBUTE *attr;
isc_mem_t *mctx;
@@ -1081,7 +1087,12 @@ pkcs11dh_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
attr = pk11_attribute_bytype(dh, CKA_PRIME);
INSIST(attr != NULL);
- key->key_size = pk11_numbits(attr->pValue, attr->ulValueLen);
+
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
return (ISC_R_SUCCESS);
diff --git a/lib/dns/pkcs11dsa_link.c b/lib/dns/pkcs11dsa_link.c
index 8d0fc62..3a8a0bb 100644
--- a/lib/dns/pkcs11dsa_link.c
+++ b/lib/dns/pkcs11dsa_link.c
@@ -982,6 +982,7 @@ pkcs11dsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
dst_private_t priv;
isc_result_t ret;
int i;
+ unsigned int bits;
pk11_object_t *dsa = NULL;
CK_ATTRIBUTE *attr;
isc_mem_t *mctx = key->mctx;
@@ -1071,7 +1072,12 @@ pkcs11dsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
attr = pk11_attribute_bytype(dsa, CKA_PRIME);
INSIST(attr != NULL);
- key->key_size = pk11_numbits(attr->pValue, attr->ulValueLen);
+
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
return (ISC_R_SUCCESS);
diff --git a/lib/dns/pkcs11rsa_link.c b/lib/dns/pkcs11rsa_link.c
index af6008d..9a736dd 100644
--- a/lib/dns/pkcs11rsa_link.c
+++ b/lib/dns/pkcs11rsa_link.c
@@ -333,6 +333,7 @@ pkcs11rsa_createctx_verify(dst_key_t *key, unsigned int maxbits,
key->key_alg == DST_ALG_RSASHA256 ||
key->key_alg == DST_ALG_RSASHA512);
#endif
+ REQUIRE(maxbits <= RSA_MAX_PUBEXP_BITS);
/*
* Reject incorrect RSA key lengths.
@@ -376,6 +377,7 @@ pkcs11rsa_createctx_verify(dst_key_t *key, unsigned int maxbits,
for (attr = pk11_attribute_first(rsa);
attr != NULL;
attr = pk11_attribute_next(rsa, attr))
+ {
switch (attr->type) {
case CKA_MODULUS:
INSIST(keyTemplate[5].type == attr->type);
@@ -396,12 +398,16 @@ pkcs11rsa_createctx_verify(dst_key_t *key, unsigned int maxbits,
memmove(keyTemplate[6].pValue, attr->pValue,
attr->ulValueLen);
keyTemplate[6].ulValueLen = attr->ulValueLen;
- if (pk11_numbits(attr->pValue,
- attr->ulValueLen) > maxbits &&
- maxbits != 0)
+ unsigned int bits;
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen,
+ &bits);
+ if (ret != ISC_R_SUCCESS ||
+ (bits > maxbits && maxbits != 0)) {
DST_RET(DST_R_VERIFYFAILURE);
+ }
break;
}
+ }
pk11_ctx->object = CK_INVALID_HANDLE;
pk11_ctx->ontoken = ISC_FALSE;
PK11_RET(pkcs_C_CreateObject,
@@ -1075,6 +1081,7 @@ pkcs11rsa_verify(dst_context_t *dctx, const isc_region_t *sig) {
keyTemplate[5].ulValueLen = attr->ulValueLen;
break;
case CKA_PUBLIC_EXPONENT:
+ unsigned int bits;
INSIST(keyTemplate[6].type == attr->type);
keyTemplate[6].pValue = isc_mem_get(dctx->mctx,
attr->ulValueLen);
@@ -1083,10 +1090,12 @@ pkcs11rsa_verify(dst_context_t *dctx, const isc_region_t *sig) {
memmove(keyTemplate[6].pValue, attr->pValue,
attr->ulValueLen);
keyTemplate[6].ulValueLen = attr->ulValueLen;
- if (pk11_numbits(attr->pValue,
- attr->ulValueLen)
- > RSA_MAX_PUBEXP_BITS)
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen,
+ &bits);
+ if (ret != ISC_R_SUCCESS || bits > RSA_MAX_PUBEXP_BITS)
+ {
DST_RET(DST_R_VERIFYFAILURE);
+ }
break;
}
pk11_ctx->object = CK_INVALID_HANDLE;
@@ -1463,6 +1472,8 @@ pkcs11rsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
CK_BYTE *exponent = NULL, *modulus = NULL;
CK_ATTRIBUTE *attr;
unsigned int length;
+ unsigned int bits;
+ isc_result_t ret = ISC_R_SUCCESS;
isc_buffer_remainingregion(data, &r);
if (r.length == 0)
@@ -1480,9 +1491,7 @@ pkcs11rsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
if (e_bytes == 0) {
if (r.length < 2) {
- isc_safe_memwipe(rsa, sizeof(*rsa));
- isc_mem_put(key->mctx, rsa, sizeof(*rsa));
- return (DST_R_INVALIDPUBLICKEY);
+ DST_RET(DST_R_INVALIDPUBLICKEY);
}
e_bytes = (*r.base) << 8;
isc_region_consume(&r, 1);
@@ -1491,16 +1500,18 @@ pkcs11rsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
}
if (r.length < e_bytes) {
- isc_safe_memwipe(rsa, sizeof(*rsa));
- isc_mem_put(key->mctx, rsa, sizeof(*rsa));
- return (DST_R_INVALIDPUBLICKEY);
+ DST_RET(DST_R_INVALIDPUBLICKEY);
}
exponent = r.base;
isc_region_consume(&r, e_bytes);
modulus = r.base;
mod_bytes = r.length;
- key->key_size = pk11_numbits(modulus, mod_bytes);
+ ret = pk11_numbits(modulus, mod_bytes, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
isc_buffer_forward(data, length);
@@ -1550,9 +1561,12 @@ pkcs11rsa_fromdns(dst_key_t *key, isc_buffer_t *data) {
rsa->repr,
rsa->attrcnt * sizeof(*attr));
}
+ ret = ISC_R_NOMEMORY;
+
+ err:
isc_safe_memwipe(rsa, sizeof(*rsa));
isc_mem_put(key->mctx, rsa, sizeof(*rsa));
- return (ISC_R_NOMEMORY);
+ return (ret);
}
static isc_result_t
@@ -1731,6 +1745,7 @@ pkcs11rsa_fetch(dst_key_t *key, const char *engine, const char *label,
pk11_object_t *pubrsa;
pk11_context_t *pk11_ctx = NULL;
isc_result_t ret;
+ unsigned int bits;
if (label == NULL)
return (DST_R_NOENGINE);
@@ -1815,7 +1830,11 @@ pkcs11rsa_fetch(dst_key_t *key, const char *engine, const char *label,
attr = pk11_attribute_bytype(rsa, CKA_MODULUS);
INSIST(attr != NULL);
- key->key_size = pk11_numbits(attr->pValue, attr->ulValueLen);
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
return (ISC_R_SUCCESS);
@@ -1901,6 +1920,7 @@ pkcs11rsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
CK_ATTRIBUTE *attr;
isc_mem_t *mctx = key->mctx;
const char *engine = NULL, *label = NULL;
+ unsigned int bits;
/* read private key file */
ret = dst__privstruct_parse(key, DST_ALG_RSA, lexer, mctx, &priv);
@@ -2044,12 +2064,22 @@ pkcs11rsa_parse(dst_key_t *key, isc_lex_t *lexer, dst_key_t *pub) {
attr = pk11_attribute_bytype(rsa, CKA_MODULUS);
INSIST(attr != NULL);
- key->key_size = pk11_numbits(attr->pValue, attr->ulValueLen);
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
attr = pk11_attribute_bytype(rsa, CKA_PUBLIC_EXPONENT);
INSIST(attr != NULL);
- if (pk11_numbits(attr->pValue, attr->ulValueLen) > RSA_MAX_PUBEXP_BITS)
+
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ if (bits > RSA_MAX_PUBEXP_BITS) {
DST_RET(ISC_R_RANGE);
+ }
dst__privstruct_free(&priv, mctx);
isc_safe_memwipe(&priv, sizeof(priv));
@@ -2084,6 +2114,7 @@ pkcs11rsa_fromlabel(dst_key_t *key, const char *engine, const char *label,
pk11_context_t *pk11_ctx = NULL;
isc_result_t ret;
unsigned int i;
+ unsigned int bits;
UNUSED(pin);
@@ -2178,12 +2209,22 @@ pkcs11rsa_fromlabel(dst_key_t *key, const char *engine, const char *label,
attr = pk11_attribute_bytype(rsa, CKA_PUBLIC_EXPONENT);
INSIST(attr != NULL);
- if (pk11_numbits(attr->pValue, attr->ulValueLen) > RSA_MAX_PUBEXP_BITS)
+
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ if (bits > RSA_MAX_PUBEXP_BITS) {
DST_RET(ISC_R_RANGE);
+ }
attr = pk11_attribute_bytype(rsa, CKA_MODULUS);
INSIST(attr != NULL);
- key->key_size = pk11_numbits(attr->pValue, attr->ulValueLen);
+ ret = pk11_numbits(attr->pValue, attr->ulValueLen, &bits);
+ if (ret != ISC_R_SUCCESS) {
+ goto err;
+ }
+ key->key_size = bits;
pk11_return_session(pk11_ctx);
isc_safe_memwipe(pk11_ctx, sizeof(*pk11_ctx));
diff --git a/lib/isc/include/pk11/internal.h b/lib/isc/include/pk11/internal.h
index 603712a..b9680bc 100644
--- a/lib/isc/include/pk11/internal.h
+++ b/lib/isc/include/pk11/internal.h
@@ -27,7 +27,8 @@ void pk11_mem_put(void *ptr, size_t size);
CK_SLOT_ID pk11_get_best_token(pk11_optype_t optype);
-unsigned int pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt);
+isc_result_t
+pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt, unsigned int *bits);
CK_ATTRIBUTE *pk11_attribute_first(const pk11_object_t *obj);
diff --git a/lib/isc/pk11.c b/lib/isc/pk11.c
index 48e1031..792b2e3 100644
--- a/lib/isc/pk11.c
+++ b/lib/isc/pk11.c
@@ -985,13 +985,15 @@ pk11_get_best_token(pk11_optype_t optype) {
return (token->slotid);
}
-unsigned int
-pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt) {
+isc_result_t
+pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt, unsigned int *bits) {
unsigned int bitcnt, i;
CK_BYTE top;
- if (bytecnt == 0)
- return (0);
+ if (bytecnt == 0) {
+ *bits = 0;
+ return (ISC_R_SUCCESS);
+ }
bitcnt = bytecnt * 8;
for (i = 0; i < bytecnt; i++) {
top = data[i];
@@ -999,25 +1001,41 @@ pk11_numbits(CK_BYTE_PTR data, unsigned int bytecnt) {
bitcnt -= 8;
continue;
}
- if (top & 0x80)
- return (bitcnt);
- if (top & 0x40)
- return (bitcnt - 1);
- if (top & 0x20)
- return (bitcnt - 2);
- if (top & 0x10)
- return (bitcnt - 3);
- if (top & 0x08)
- return (bitcnt - 4);
- if (top & 0x04)
- return (bitcnt - 5);
- if (top & 0x02)
- return (bitcnt - 6);
- if (top & 0x01)
- return (bitcnt - 7);
+ if (top & 0x80) {
+ *bits = bitcnt;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x40) {
+ *bits = bitcnt - 1;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x20) {
+ *bits = bitcnt - 2;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x10) {
+ *bits = bitcnt - 3;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x08) {
+ *bits = bitcnt - 4;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x04) {
+ *bits = bitcnt - 5;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x02) {
+ *bits = bitcnt - 6;
+ return (ISC_R_SUCCESS);
+ }
+ if (top & 0x01) {
+ *bits = bitcnt - 7;
+ return (ISC_R_SUCCESS);
+ }
break;
}
- INSIST(0);
+ return (ISC_R_RANGE);
}
CK_ATTRIBUTE *
--
2.26.2