Mercurial > dropbear
view libtomcrypt/src/hashes/md4.c @ 1788:1fc0012b9c38
Fix handling of replies to global requests (#112)
The current code assumes that all global requests want / need a reply.
This isn't always true and the request itself indicates if it wants a
reply or not.
It causes a specific problem with [email protected] messages.
These are sent by OpenSSH after authentication to inform the client of
potential other host keys for the host. This can be used to add a new
type of host key or to rotate host keys.
The initial information message from the server is sent as a global
request, but with want_reply set to false. This means that the server
doesn't expect an answer to this message. Instead the client needs to
send a prove request as a reply if it wants to receive proof of
ownership for the host keys.
The bug doesn't cause any current problems with due to how OpenSSH
treats receiving the failure message. It instead treats it as a
keepalive message and further ignores it.
Arguably this is a protocol violation though of Dropbear and it is only
accidental that it doesn't cause a problem with OpenSSH.
The bug was found when adding host keys support to libssh, which is more
strict protocol wise and treats the unexpected failure message an error,
also see https://gitlab.com/libssh/libssh-mirror/-/merge_requests/145
for more information.
The fix here is to honor the want_reply flag in the global request and
to only send a reply if the other side expects a reply.
author | Dirkjan Bussink <d.bussink@gmail.com> |
---|---|
date | Thu, 10 Dec 2020 16:13:13 +0100 |
parents | 6dba84798cd5 |
children |
line wrap: on
line source
/* 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" /** @param md4.c Submitted by Dobes Vandermeer ([email protected]) */ #ifdef LTC_MD4 const struct ltc_hash_descriptor md4_desc = { "md4", 6, 16, 64, /* OID */ { 1, 2, 840, 113549, 2, 4, }, 6, &md4_init, &md4_process, &md4_done, &md4_test, NULL }; #define S11 3 #define S12 7 #define S13 11 #define S14 19 #define S21 3 #define S22 5 #define S23 9 #define S24 13 #define S31 3 #define S32 9 #define S33 11 #define S34 15 /* F, G and H are basic LTC_MD4 functions. */ #define F(x, y, z) (z ^ (x & (y ^ z))) #define G(x, y, z) ((x & y) | (z & (x | y))) #define H(x, y, z) ((x) ^ (y) ^ (z)) /* ROTATE_LEFT rotates x left n bits. */ #define ROTATE_LEFT(x, n) ROLc(x, n) /* FF, GG and HH are transformations for rounds 1, 2 and 3 */ /* Rotation is separate from addition to prevent recomputation */ #define FF(a, b, c, d, x, s) { \ (a) += F ((b), (c), (d)) + (x); \ (a) = ROTATE_LEFT ((a), (s)); \ } #define GG(a, b, c, d, x, s) { \ (a) += G ((b), (c), (d)) + (x) + 0x5a827999UL; \ (a) = ROTATE_LEFT ((a), (s)); \ } #define HH(a, b, c, d, x, s) { \ (a) += H ((b), (c), (d)) + (x) + 0x6ed9eba1UL; \ (a) = ROTATE_LEFT ((a), (s)); \ } #ifdef LTC_CLEAN_STACK static int _md4_compress(hash_state *md, unsigned char *buf) #else static int md4_compress(hash_state *md, unsigned char *buf) #endif { ulong32 x[16], a, b, c, d; int i; /* copy state */ a = md->md4.state[0]; b = md->md4.state[1]; c = md->md4.state[2]; d = md->md4.state[3]; /* copy the state into 512-bits into W[0..15] */ for (i = 0; i < 16; i++) { LOAD32L(x[i], buf + (4*i)); } /* Round 1 */ FF (a, b, c, d, x[ 0], S11); /* 1 */ FF (d, a, b, c, x[ 1], S12); /* 2 */ FF (c, d, a, b, x[ 2], S13); /* 3 */ FF (b, c, d, a, x[ 3], S14); /* 4 */ FF (a, b, c, d, x[ 4], S11); /* 5 */ FF (d, a, b, c, x[ 5], S12); /* 6 */ FF (c, d, a, b, x[ 6], S13); /* 7 */ FF (b, c, d, a, x[ 7], S14); /* 8 */ FF (a, b, c, d, x[ 8], S11); /* 9 */ FF (d, a, b, c, x[ 9], S12); /* 10 */ FF (c, d, a, b, x[10], S13); /* 11 */ FF (b, c, d, a, x[11], S14); /* 12 */ FF (a, b, c, d, x[12], S11); /* 13 */ FF (d, a, b, c, x[13], S12); /* 14 */ FF (c, d, a, b, x[14], S13); /* 15 */ FF (b, c, d, a, x[15], S14); /* 16 */ /* Round 2 */ GG (a, b, c, d, x[ 0], S21); /* 17 */ GG (d, a, b, c, x[ 4], S22); /* 18 */ GG (c, d, a, b, x[ 8], S23); /* 19 */ GG (b, c, d, a, x[12], S24); /* 20 */ GG (a, b, c, d, x[ 1], S21); /* 21 */ GG (d, a, b, c, x[ 5], S22); /* 22 */ GG (c, d, a, b, x[ 9], S23); /* 23 */ GG (b, c, d, a, x[13], S24); /* 24 */ GG (a, b, c, d, x[ 2], S21); /* 25 */ GG (d, a, b, c, x[ 6], S22); /* 26 */ GG (c, d, a, b, x[10], S23); /* 27 */ GG (b, c, d, a, x[14], S24); /* 28 */ GG (a, b, c, d, x[ 3], S21); /* 29 */ GG (d, a, b, c, x[ 7], S22); /* 30 */ GG (c, d, a, b, x[11], S23); /* 31 */ GG (b, c, d, a, x[15], S24); /* 32 */ /* Round 3 */ HH (a, b, c, d, x[ 0], S31); /* 33 */ HH (d, a, b, c, x[ 8], S32); /* 34 */ HH (c, d, a, b, x[ 4], S33); /* 35 */ HH (b, c, d, a, x[12], S34); /* 36 */ HH (a, b, c, d, x[ 2], S31); /* 37 */ HH (d, a, b, c, x[10], S32); /* 38 */ HH (c, d, a, b, x[ 6], S33); /* 39 */ HH (b, c, d, a, x[14], S34); /* 40 */ HH (a, b, c, d, x[ 1], S31); /* 41 */ HH (d, a, b, c, x[ 9], S32); /* 42 */ HH (c, d, a, b, x[ 5], S33); /* 43 */ HH (b, c, d, a, x[13], S34); /* 44 */ HH (a, b, c, d, x[ 3], S31); /* 45 */ HH (d, a, b, c, x[11], S32); /* 46 */ HH (c, d, a, b, x[ 7], S33); /* 47 */ HH (b, c, d, a, x[15], S34); /* 48 */ /* Update our state */ md->md4.state[0] = md->md4.state[0] + a; md->md4.state[1] = md->md4.state[1] + b; md->md4.state[2] = md->md4.state[2] + c; md->md4.state[3] = md->md4.state[3] + d; return CRYPT_OK; } #ifdef LTC_CLEAN_STACK static int md4_compress(hash_state *md, unsigned char *buf) { int err; err = _md4_compress(md, buf); burn_stack(sizeof(ulong32) * 20 + sizeof(int)); return err; } #endif /** Initialize the hash state @param md The hash state you wish to initialize @return CRYPT_OK if successful */ int md4_init(hash_state * md) { LTC_ARGCHK(md != NULL); md->md4.state[0] = 0x67452301UL; md->md4.state[1] = 0xefcdab89UL; md->md4.state[2] = 0x98badcfeUL; md->md4.state[3] = 0x10325476UL; md->md4.length = 0; md->md4.curlen = 0; return CRYPT_OK; } /** Process a block of memory though the hash @param md The hash state @param in The data to hash @param inlen The length of the data (octets) @return CRYPT_OK if successful */ HASH_PROCESS(md4_process, md4_compress, md4, 64) /** Terminate the hash to get the digest @param md The hash state @param out [out] The destination of the hash (16 bytes) @return CRYPT_OK if successful */ int md4_done(hash_state * md, unsigned char *out) { int i; LTC_ARGCHK(md != NULL); LTC_ARGCHK(out != NULL); if (md->md4.curlen >= sizeof(md->md4.buf)) { return CRYPT_INVALID_ARG; } /* increase the length of the message */ md->md4.length += md->md4.curlen * 8; /* append the '1' bit */ md->md4.buf[md->md4.curlen++] = (unsigned char)0x80; /* if the length is currently above 56 bytes we append zeros * then compress. Then we can fall back to padding zeros and length * encoding like normal. */ if (md->md4.curlen > 56) { while (md->md4.curlen < 64) { md->md4.buf[md->md4.curlen++] = (unsigned char)0; } md4_compress(md, md->md4.buf); md->md4.curlen = 0; } /* pad upto 56 bytes of zeroes */ while (md->md4.curlen < 56) { md->md4.buf[md->md4.curlen++] = (unsigned char)0; } /* store length */ STORE64L(md->md4.length, md->md4.buf+56); md4_compress(md, md->md4.buf); /* copy output */ for (i = 0; i < 4; i++) { STORE32L(md->md4.state[i], out+(4*i)); } #ifdef LTC_CLEAN_STACK zeromem(md, sizeof(hash_state)); #endif return CRYPT_OK; } /** Self-test the hash @return CRYPT_OK if successful, CRYPT_NOP if self-tests have been disabled */ int md4_test(void) { #ifndef LTC_TEST return CRYPT_NOP; #else static const struct md4_test_case { const char *input; unsigned char hash[16]; } tests[] = { { "", {0x31, 0xd6, 0xcf, 0xe0, 0xd1, 0x6a, 0xe9, 0x31, 0xb7, 0x3c, 0x59, 0xd7, 0xe0, 0xc0, 0x89, 0xc0} }, { "a", {0xbd, 0xe5, 0x2c, 0xb3, 0x1d, 0xe3, 0x3e, 0x46, 0x24, 0x5e, 0x05, 0xfb, 0xdb, 0xd6, 0xfb, 0x24} }, { "abc", {0xa4, 0x48, 0x01, 0x7a, 0xaf, 0x21, 0xd8, 0x52, 0x5f, 0xc1, 0x0a, 0xe8, 0x7a, 0xa6, 0x72, 0x9d} }, { "message digest", {0xd9, 0x13, 0x0a, 0x81, 0x64, 0x54, 0x9f, 0xe8, 0x18, 0x87, 0x48, 0x06, 0xe1, 0xc7, 0x01, 0x4b} }, { "abcdefghijklmnopqrstuvwxyz", {0xd7, 0x9e, 0x1c, 0x30, 0x8a, 0xa5, 0xbb, 0xcd, 0xee, 0xa8, 0xed, 0x63, 0xdf, 0x41, 0x2d, 0xa9} }, { "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", {0x04, 0x3f, 0x85, 0x82, 0xf2, 0x41, 0xdb, 0x35, 0x1c, 0xe6, 0x27, 0xe1, 0x53, 0xe7, 0xf0, 0xe4} }, { "12345678901234567890123456789012345678901234567890123456789012345678901234567890", {0xe3, 0x3b, 0x4d, 0xdc, 0x9c, 0x38, 0xf2, 0x19, 0x9c, 0x3e, 0x7b, 0x16, 0x4f, 0xcc, 0x05, 0x36} }, }; int i; unsigned char tmp[16]; hash_state md; for(i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) { md4_init(&md); md4_process(&md, (unsigned char *)tests[i].input, (unsigned long)strlen(tests[i].input)); md4_done(&md, tmp); if (compare_testvector(tmp, sizeof(tmp), tests[i].hash, sizeof(tests[i].hash), "MD4", i)) { return CRYPT_FAIL_TESTVECTOR; } } return CRYPT_OK; #endif } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */