Mercurial > dropbear
view libtommath/bn_mp_init_multi.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 | 1051e4eea25a |
children |
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#include "tommath_private.h" #ifdef BN_MP_INIT_MULTI_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ #include <stdarg.h> mp_err mp_init_multi(mp_int *mp, ...) { mp_err err = MP_OKAY; /* Assume ok until proven otherwise */ int n = 0; /* Number of ok inits */ mp_int *cur_arg = mp; va_list args; va_start(args, mp); /* init args to next argument from caller */ while (cur_arg != NULL) { if (mp_init(cur_arg) != MP_OKAY) { /* Oops - error! Back-track and mp_clear what we already succeeded in init-ing, then return error. */ va_list clean_args; /* now start cleaning up */ cur_arg = mp; va_start(clean_args, mp); while (n-- != 0) { mp_clear(cur_arg); cur_arg = va_arg(clean_args, mp_int *); } va_end(clean_args); err = MP_MEM; break; } n++; cur_arg = va_arg(args, mp_int *); } va_end(args); return err; /* Assumed ok, if error flagged above. */ } #endif