c0667361a5
The previous state of the patch did not work correctly when used with negative salt lengths, which OpenSSL uses a magic values. Setting the saltlength to max would yield an approved state in the indicator, while it is not approved. Additionally, update the patch to change the default PSS salt length with the current state of discussion upstream (see https://github.com/openssl/openssl/pull/19724). Resolves: rhbz#2142087 Signed-off-by: Clemens Lang <cllang@redhat.com>
111 lines
4.8 KiB
Diff
111 lines
4.8 KiB
Diff
From a325a23bc83f4efd60130001c417ca5b96bdbff1 Mon Sep 17 00:00:00 2001
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From: Clemens Lang <cllang@redhat.com>
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Date: Thu, 17 Nov 2022 19:33:02 +0100
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Subject: [PATCH 1/3] signature: Add indicator for PSS salt length
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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FIPS 186-4 section 5 "The RSA Digital Signature Algorithm", subsection
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5.5 "PKCS #1" says: "For RSASSA-PSS […] the length (in bytes) of the
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salt (sLen) shall satisfy 0 ≤ sLen ≤ hLen, where hLen is the length of
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the hash function output block (in bytes)."
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It is not exactly clear from this text whether hLen refers to the
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message digest or the hash function used for the mask generation
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function MGF1. PKCS#1 v2.1 suggests it is the former:
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| Typical salt lengths in octets are hLen (the length of the output of
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| the hash function Hash) and 0. In both cases the security of
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| RSASSA-PSS can be closely related to the hardness of inverting RSAVP1.
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| Bellare and Rogaway [4] give a tight lower bound for the security of
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| the original RSA-PSS scheme, which corresponds roughly to the former
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| case, while Coron [12] gives a lower bound for the related Full Domain
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| Hashing scheme, which corresponds roughly to the latter case. In [13]
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| Coron provides a general treatment with various salt lengths ranging
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| from 0 to hLen; see [27] for discussion. See also [31], which adapts
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| the security proofs in [4][13] to address the differences between the
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| original and the present version of RSA-PSS as listed in Note 1 above.
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Since OpenSSL defaults to creating signatures with the maximum salt
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length, blocking the use of longer salts would probably lead to
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significant problems in practice. Instead, introduce an explicit
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indicator that can be obtained from the EVP_PKEY_CTX object using
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EVP_PKEY_CTX_get_params() with the
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OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR
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parameter.
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Signed-off-by: Clemens Lang <cllang@redhat.com>
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---
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include/openssl/core_names.h | 1 +
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include/openssl/evp.h | 4 ++++
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providers/implementations/signature/rsa_sig.c | 18 ++++++++++++++++++
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3 files changed, 23 insertions(+)
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diff --git a/include/openssl/core_names.h b/include/openssl/core_names.h
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index 94fab83193..69c59f0b46 100644
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--- a/include/openssl/core_names.h
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+++ b/include/openssl/core_names.h
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@@ -453,6 +453,7 @@ extern "C" {
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#define OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES \
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OSSL_PKEY_PARAM_MGF1_PROPERTIES
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#define OSSL_SIGNATURE_PARAM_DIGEST_SIZE OSSL_PKEY_PARAM_DIGEST_SIZE
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+#define OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR "redhat-fips-indicator"
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/* Asym cipher parameters */
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#define OSSL_ASYM_CIPHER_PARAM_DIGEST OSSL_PKEY_PARAM_DIGEST
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diff --git a/include/openssl/evp.h b/include/openssl/evp.h
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index a5e78efd6e..f239200465 100644
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--- a/include/openssl/evp.h
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+++ b/include/openssl/evp.h
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@@ -797,6 +797,10 @@ __owur int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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__owur int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
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int *outl);
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_UNDETERMINED 0
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_APPROVED 1
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+# define EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_NOT_APPROVED 2
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+
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__owur int EVP_SignFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s,
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EVP_PKEY *pkey);
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__owur int EVP_SignFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s,
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diff --git a/providers/implementations/signature/rsa_sig.c b/providers/implementations/signature/rsa_sig.c
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index 49e7f9158a..0c45008a00 100644
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--- a/providers/implementations/signature/rsa_sig.c
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+++ b/providers/implementations/signature/rsa_sig.c
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@@ -1127,6 +1127,21 @@ static int rsa_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
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}
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}
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+#ifdef FIPS_MODULE
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+ p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR);
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+ if (p != NULL) {
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+ int fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_APPROVED;
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+ if (prsactx->pad_mode == RSA_PKCS1_PSS_PADDING) {
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+ if (prsactx->md == NULL) {
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+ fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_UNDETERMINED;
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+ } else if (rsa_pss_compute_saltlen(prsactx) > EVP_MD_get_size(prsactx->md)) {
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+ fips_indicator = EVP_SIGNATURE_REDHAT_FIPS_INDICATOR_NOT_APPROVED;
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+ }
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+ }
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+ return OSSL_PARAM_set_int(p, fips_indicator);
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+ }
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+#endif
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+
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return 1;
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}
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@@ -1136,6 +1151,9 @@ static const OSSL_PARAM known_gettable_ctx_params[] = {
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0),
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OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0),
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+#ifdef FIPS_MODULE
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+ OSSL_PARAM_int(OSSL_SIGNATURE_PARAM_REDHAT_FIPS_INDICATOR, NULL),
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+#endif
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OSSL_PARAM_END
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};
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--
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2.38.1
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