Mercurial > dropbear
view libtomcrypt/src/pk/asn1/der/sequence/der_sequence_shrink.c @ 1790:42745af83b7d
Introduce extra delay before closing unauthenticated sessions
To make it harder for attackers, introduce a delay to keep an
unauthenticated session open a bit longer, thus blocking a connection
slot until after the delay.
Without this, while there is a limit on the amount of attempts an attacker
can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to
handle one attempt is still short and thus for each of the allowed parallel
attempts many attempts can be chained one after the other. The attempt rate
is then:
"MAX_UNAUTH_PER_IP / <process time of one attempt>".
With the delay, this rate becomes:
"MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author | Thomas De Schampheleire <thomas.de_schampheleire@nokia.com> |
---|---|
date | Wed, 15 Feb 2017 13:53:04 +0100 |
parents | 6dba84798cd5 |
children |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. */ #include "tomcrypt.h" /** @file der_sequence_shrink.c Free memory allocated for CONSTRUCTED, SET or SEQUENCE elements by der_decode_sequence_flexi(), Steffen Jaeckel */ #ifdef LTC_DER /** Free memory allocated for CONSTRUCTED, SET or SEQUENCE elements by der_decode_sequence_flexi() @param in The list to shrink */ void der_sequence_shrink(ltc_asn1_list *in) { if (!in) return; /* now walk the list and free stuff */ while (in != NULL) { /* is there a child? */ if (in->child) { der_sequence_shrink(in->child); } switch (in->type) { case LTC_ASN1_CONSTRUCTED: case LTC_ASN1_SET: case LTC_ASN1_SEQUENCE : if (in->data != NULL) { XFREE(in->data); in->data = NULL; } break; default: break; } /* move to next and free current */ in = in->next; } } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */