| Message ID | 20221220140458.2666637-1-arne@rfc2549.org |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [Openvpn-devel,v2,1/8] Make management password check constant time | expand |
Acked-by: Gert Doering <gert@greenie.muc.de> Works. Password entered must be the right one now, not shorter or longer :-) Your patch has been applied to the master and release/2.6 branch. I think it would also be appropriate for 2.5, but there is no min_uint() (came as part of commit 3f8fb2b2c), so the patch "as is" breaks compilation on older branches. commit e567f34262b0670fd51cbbcb6c6866b046454cee (master) commit 6a82929076ed97f6c37161de266d3dcbe14d55c8 (release/2.6) Author: Arne Schwabe Date: Tue Dec 20 15:04:58 2022 +0100 Make management password check constant time Signed-off-by: Arne Schwabe <arne@rfc2549.org> Acked-by: Gert Doering <gert@greenie.muc.de> Message-Id: <20221220140458.2666637-1-arne@rfc2549.org> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25784.html Signed-off-by: Gert Doering <gert@greenie.muc.de> -- kind regards, Gert Doering
diff --git a/src/openvpn/manage.c b/src/openvpn/manage.c index b11de224d..5465b7e9b 100644 --- a/src/openvpn/manage.c +++ b/src/openvpn/manage.c @@ -198,7 +198,12 @@ man_check_password(struct management *man, const char *line) { if (man_password_needed(man)) { - if (streq(line, man->settings.up.password)) + /* This comparison is not fixed time but since strlen(time) is based on + * the attacker choice, it should not give any indication of the real + * password length, use + 1 to include the NUL byte that terminates the + * string*/ + size_t compare_len = min_uint(strlen(line) + 1, sizeof(man->settings.up.password)); + if (memcmp_constant_time(line, man->settings.up.password, compare_len) == 0) { man->connection.password_verified = true; msg(M_CLIENT, "SUCCESS: password is correct");
This changes the password check on the management interface to be constant time. Normally the management port should not be exposed in a way that allows an attacker to even interact with it but making the check constant time as an additional layer of security is always good. Patch v2: include NUL byte in comparison Reported-by: Connor Edwards <cedw@pm.me> Signed-off-by: Arne Schwabe <arne@rfc2549.org> --- src/openvpn/manage.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)