Mercurial > dropbear
view libtomcrypt/src/headers/tomcrypt_argchk.h @ 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 | 1ff2a1034c52 |
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. */ /* Defines the LTC_ARGCHK macro used within the library */ /* ARGTYPE is defined in tomcrypt_cfg.h */ #if ARGTYPE == 0 #include <signal.h> /* portability macros for compiler-specific code attributes */ #ifdef __GNUC__ #define ATTRIB_NORETURN __attribute__((noreturn)) #else #define ATTRIB_NORETURN #endif /* this is the default LibTomCrypt macro */ #if defined(__clang__) || defined(__GNUC_MINOR__) #define NORETURN __attribute__ ((noreturn)) #else #define NORETURN #endif void crypt_argchk(const char *v, const char *s, int d) NORETURN; #define LTC_ARGCHK(x) do { if (!(x)) { crypt_argchk(#x, __FILE__, __LINE__); } }while(0) #define LTC_ARGCHKVD(x) do { if (!(x)) { crypt_argchk(#x, __FILE__, __LINE__); } }while(0) #elif ARGTYPE == 1 /* fatal type of error */ #define LTC_ARGCHK(x) assert((x)) #define LTC_ARGCHKVD(x) LTC_ARGCHK(x) #elif ARGTYPE == 2 #define LTC_ARGCHK(x) if (!(x)) { fprintf(stderr, "\nwarning: ARGCHK failed at %s:%d\n", __FILE__, __LINE__); } #define LTC_ARGCHKVD(x) LTC_ARGCHK(x) #elif ARGTYPE == 3 #define LTC_ARGCHK(x) #define LTC_ARGCHKVD(x) LTC_ARGCHK(x) #elif ARGTYPE == 4 #define LTC_ARGCHK(x) if (!(x)) return CRYPT_INVALID_ARG; #define LTC_ARGCHKVD(x) if (!(x)) return; #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */