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ssl: do not choose auto DH groups that are weaker than the security level

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Fixes #15808

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15818)
This commit is contained in:
Pauli 2021-06-18 12:54:24 +10:00
parent b9d022d78f
commit d7b5c648d6
3 changed files with 31 additions and 10 deletions
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33
ssl/ssl_cert.c
View File

@ -960,18 +960,36 @@ int ssl_cert_set_cert_store(CERT *c, X509_STORE *store, int chain, int ref)
return 1;
}
int ssl_get_security_level_bits(const SSL *s, const SSL_CTX *ctx, int *levelp)
{
int level;
static const int minbits_table[5 + 1] = { 0, 80, 112, 128, 192, 256 };
if (ctx != NULL)
level = SSL_CTX_get_security_level(ctx);
else
level = SSL_get_security_level(s);
if (level > 5)
level = 5;
else if (level < 0)
level = 0;
if (levelp != NULL)
*levelp = level;
return minbits_table[level];
}
static int ssl_security_default_callback(const SSL *s, const SSL_CTX *ctx,
int op, int bits, int nid, void *other,
void *ex)
{
int level, minbits;
static const int minbits_table[5] = { 80, 112, 128, 192, 256 };
if (ctx)
level = SSL_CTX_get_security_level(ctx);
else
level = SSL_get_security_level(s);
if (level <= 0) {
minbits = ssl_get_security_level_bits(s, ctx, &level);
if (level == 0) {
/*
* No EDH keys weaker than 1024-bits even at level 0, otherwise,
* anything goes.
@ -980,9 +998,6 @@ static int ssl_security_default_callback(const SSL *s, const SSL_CTX *ctx,
return 0;
return 1;
}
if (level > 5)
level = 5;
minbits = minbits_table[level - 1];
switch (op) {
case SSL_SECOP_CIPHER_SUPPORTED:
case SSL_SECOP_CIPHER_SHARED:

1
ssl/ssl_local.h
View File

@ -2436,6 +2436,7 @@ __owur int ssl_cert_set_cert_store(CERT *c, X509_STORE *store, int chain,
__owur int ssl_security(const SSL *s, int op, int bits, int nid, void *other);
__owur int ssl_ctx_security(const SSL_CTX *ctx, int op, int bits, int nid,
void *other);
int ssl_get_security_level_bits(const SSL *s, const SSL_CTX *ctx, int *levelp);
__owur int ssl_cert_lookup_by_nid(int nid, size_t *pidx);
__owur const SSL_CERT_LOOKUP *ssl_cert_lookup_by_pkey(const EVP_PKEY *pk,

7
ssl/t1_lib.c
View File

@ -2884,7 +2884,7 @@ EVP_PKEY *ssl_get_auto_dh(SSL *s)
{
EVP_PKEY *dhp = NULL;
BIGNUM *p;
int dh_secbits = 80;
int dh_secbits = 80, sec_level_bits;
EVP_PKEY_CTX *pctx = NULL;
OSSL_PARAM_BLD *tmpl = NULL;
OSSL_PARAM *params = NULL;
@ -2902,6 +2902,11 @@ EVP_PKEY *ssl_get_auto_dh(SSL *s)
}
}
/* Do not pick a prime that is too weak for the current security level */
sec_level_bits = ssl_get_security_level_bits(s, NULL, NULL);
if (dh_secbits < sec_level_bits)
dh_secbits = sec_level_bits;
if (dh_secbits >= 192)
p = BN_get_rfc3526_prime_8192(NULL);
else if (dh_secbits >= 152)