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Include "!eNULL" in SSL_DEFAULT_CIPHER_LIST to make sure that a

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ciphersuite string such as "DEFAULT:RSA" cannot enable
authentication-only ciphersuites.

Also, change ssl_create_cipher_list() so that it no longer
starts with an arbitrary ciphersuite ordering, but instead
uses the logic that we previously had in SSL_DEFEAULT_CIPHER_LIST.
SSL_DEFAULT_CIPHER_LIST simplifies into just "ALL:!aNULL:!eNULL".
This commit is contained in:
Bodo Möller 2007-02-19 18:41:41 +00:00
parent 2afe316721
commit 0a05123a6c
3 changed files with 62 additions and 2 deletions
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20
CHANGES
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@ -4,6 +4,16 @@
Changes between 0.9.8e and 0.9.9 [xx XXX xxxx]
*) Change ssl_create_cipher_list() so that it automatically
arranges the ciphersuites in reasonable order before starting
to process the rule string. Thus, the definition for "DEFAULT"
(SSL_DEFAULT_CIPHER_LIST) now is just "ALL:!aNULL:!eNULL", but
remains equivalent to "AES:ALL:!aNULL:!eNULL:+aECDH:+kRSA:+RC4:@STRENGTH".
This makes it much easier to arrive at a reasonable default order
in applications for which anonymous ciphers are OK (meaning
that you can't actually use DEFAULT).
[Bodo Moeller; suggested by Victor Duchovni]
*) Split the SSL/TLS algorithm mask (as used for ciphersuite string
processing) into multiple integers instead of setting
"SSL_MKEY_MASK" bits, "SSL_AUTH_MASK" bits, "SSL_ENC_MASK",
@ -452,6 +462,11 @@
Changes between 0.9.8d and 0.9.8e [XX xxx XXXX]
*) Include "!eNULL" in SSL_DEFAULT_CIPHER_LIST to make sure that
a ciphersuite string such as "DEFAULT:RSA" cannot enable
authentication-only ciphersuites.
[Bodo Moeller]
*) Since AES128 and AES256 (and similarly Camellia128 and
Camellia256) share a single mask bit in the logic of
ssl/ssl_ciph.c, the code for masking out disabled ciphers needs a
@ -1488,6 +1503,11 @@
Changes between 0.9.7l and 0.9.7m [xx XXX xxxx]
*) Include "!eNULL" in SSL_DEFAULT_CIPHER_LIST to make sure that
a ciphersuite string such as "DEFAULT:RSA" cannot enable
authentication-only ciphersuites.
[Bodo Moeller]
*) Since AES128 and AES256 share a single mask bit in the logic of
ssl/ssl_ciph.c, the code for masking out disabled ciphers needs a
kludge to work properly if AES128 is available and AES256 isn't.

9
ssl/ssl.h
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@ -315,8 +315,13 @@ extern "C" {
/* The following cipher list is used by default.
* It also is substituted when an application-defined cipher list string
* starts with 'DEFAULT'. */
#define SSL_DEFAULT_CIPHER_LIST "AES:CAMELLIA:ALL:!ADH:!AECDH:+aECDH:+kRSA:+RC4:@STRENGTH"
/* low priority for ciphersuites w/o forwared secrecy (fixed ECDH, RSA key exchange), and for RC4 */
#define SSL_DEFAULT_CIPHER_LIST "ALL:!aNULL:!eNULL"
/* As of OpenSSL 0.9.9, ssl_create_cipher_list() in ssl/ssl_ciph.c always
* starts with a reasonable order, and all we have to do for DEFAULT is
* throwing out anonymous and unencrypted ciphersuites!
* (The latter are not actually enabled by ALL, but "ALL:RSA" would enable
* some of them.)
*/
/* Used in SSL_set_shutdown()/SSL_get_shutdown(); */
#define SSL_SENT_SHUTDOWN 1

35
ssl/ssl_ciph.c
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@ -1120,6 +1120,40 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_list(const SSL_METHOD *ssl_method,
disabled_mkey, disabled_auth, disabled_enc, disabled_mac, disabled_ssl,
co_list, &head, &tail);
/* Now arrange all ciphers by preference: */
/* Temporarily enabled AES first (preferred cipher) */
ssl_cipher_apply_rule(0, 0, 0, SSL_AES, 0, 0, 0, CIPHER_ADD, -1, &head, &tail);
/* Temporarily enable everything else */
ssl_cipher_apply_rule(0, 0, 0, 0, 0, 0, 0, CIPHER_ADD, -1, &head, &tail);
/* Move anonymous ciphers to the end. Usually, these will remain disabled.
* (For applications that allow them, they aren't too bad, but we prefer
* authenticated ciphers.) */
ssl_cipher_apply_rule(0, 0, SSL_aNULL, 0, 0, 0, 0, CIPHER_ORD, -1, &head, &tail);
/* Move ciphers without forward secrecy to then end */
ssl_cipher_apply_rule(0, 0, SSL_aECDH, 0, 0, 0, 0, CIPHER_ORD, -1, &head, &tail);
ssl_cipher_apply_rule(0, SSL_kRSA, 0, 0, 0, 0, 0, CIPHER_ORD, -1, &head, &tail);
ssl_cipher_apply_rule(0, 0, SSL_kPSK, 0, 0, 0, 0, CIPHER_ORD, -1, &head, &tail);
/* RC4 is sort-of broken -- move the the end */
ssl_cipher_apply_rule(0, 0, 0, SSL_RC4, 0, 0, 0, CIPHER_ORD, -1, &head, &tail);
/* Now sort by symmetric encryption strength. The above ordering remains
* in force within each class */
if (!ssl_cipher_strength_sort(&head, &tail))
{
OPENSSL_free(co_list);
return NULL;
}
/* Now disable everything (maintaining the ordering!) */
ssl_cipher_apply_rule(0, 0, 0, 0, 0, 0, 0, CIPHER_DEL, -1, &head, &tail);
/*
* We also need cipher aliases for selecting based on the rule_str.
* There might be two types of entries in the rule_str: 1) names
@ -1167,6 +1201,7 @@ STACK_OF(SSL_CIPHER) *ssl_create_cipher_list(const SSL_METHOD *ssl_method,
OPENSSL_free(co_list);
return(NULL);
}
/*
* Allocate new "cipherstack" for the result, return with error
* if we cannot get one.