Mercurial > dropbear
view dss.c @ 1306:34e6127ef02e
merge fixes from PuTTY import.c
toint() from misc.c
(revids are from hggit conversion)
changeset: 4620:60a336a6c85c
user: Simon Tatham <[email protected]>
date: Thu Feb 25 20:26:33 2016 +0000
files: import.c
description:
Fix potential segfaults in reading OpenSSH's ASN.1 key format.
The length coming back from ber_read_id_len might have overflowed, so
treat it as potentially negative. Also, while I'm here, accumulate it
inside ber_read_id_len as an unsigned, so as to avoid undefined
behaviour on integer overflow, and toint() it before return.
Thanks to Hanno Böck for spotting this, with the aid of AFL.
(cherry picked from commit 5b7833cd474a24ec098654dcba8cb9509f3bf2c1)
Conflicts:
import.c
(cherry-picker's note: resolving the conflict involved removing an
entire section of the original commit which fixed ECDSA code not
present on this branch)
changeset: 4619:9c6c638d98d8
user: Simon Tatham <[email protected]>
date: Sun Jul 14 10:45:54 2013 +0000
files: import.c ssh.c sshdss.c sshpubk.c sshrsa.c
description:
Tighten up a lot of casts from unsigned to int which are read by one
of the GET_32BIT macros and then used as length fields. Missing bounds
checks against zero have been added, and also I've introduced a helper
function toint() which casts from unsigned to int in such a way as to
avoid C undefined behaviour, since I'm not sure I trust compilers any
more to do the obviously sensible thing.
[originally from svn r9918]
changeset: 4618:3957829f24d3
user: Simon Tatham <[email protected]>
date: Mon Jul 08 22:36:04 2013 +0000
files: import.c sshdss.c sshrsa.c
description:
Add an assortment of extra safety checks.
[originally from svn r9896]
changeset: 4617:2cddee0bce12
user: Jacob Nevins <[email protected]>
date: Wed Dec 07 00:24:45 2005 +0000
files: import.c
description:
Institutional failure to memset() things pointed at rather than pointers.
Things should now be zeroed and memory not leaked. Spotted by Brant Thomsen.
[originally from svn r6476]
changeset: 4616:24ac78a9c71d
user: Simon Tatham <[email protected]>
date: Wed Feb 11 13:58:27 2004 +0000
files: import.c
description:
Jacob's last-minute testing found a couple of trivial bugs in
import.c, and my attempts to reproduce them in cmdgen found another
one there :-)
[originally from svn r3847]
changeset: 4615:088d39a73db0
user: Simon Tatham <[email protected]>
date: Thu Jan 22 18:52:49 2004 +0000
files: import.c
description:
Placate some gcc warnings.
[originally from svn r3761]
changeset: 4614:e4288bad4d93
parent: 1758:108b8924593d
user: Simon Tatham <[email protected]>
date: Fri Oct 03 21:21:23 2003 +0000
files: import.c
description:
My ASN.1 decoder returned wrong IDs for anything above 0x1E! Good
job it's never had to yet. Ahem.
[originally from svn r3479]
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Tue, 12 Jul 2016 23:00:01 +0800 |
parents | aaf576b27a10 |
children | 750ec4ec4cbe |
line wrap: on
line source
/* * Dropbear - a SSH2 server * * Copyright (c) 2002,2003 Matt Johnston * All rights reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. */ #include "includes.h" #include "dbutil.h" #include "bignum.h" #include "dss.h" #include "buffer.h" #include "ssh.h" #include "dbrandom.h" /* Handle DSS (Digital Signature Standard), aka DSA (D.S. Algorithm), * operations, such as key reading, signing, verification. Key generation * is in gendss.c, since it isn't required in the server itself. * * See FIPS186 or the Handbook of Applied Cryptography for details of the * algorithm */ #ifdef DROPBEAR_DSS /* Load a dss key from a buffer, initialising the values. * The key will have the same format as buf_put_dss_key. * These should be freed with dss_key_free. * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ int buf_get_dss_pub_key(buffer* buf, dropbear_dss_key *key) { TRACE(("enter buf_get_dss_pub_key")) dropbear_assert(key != NULL); m_mp_alloc_init_multi(&key->p, &key->q, &key->g, &key->y, NULL); key->x = NULL; buf_incrpos(buf, 4+SSH_SIGNKEY_DSS_LEN); /* int + "ssh-dss" */ if (buf_getmpint(buf, key->p) == DROPBEAR_FAILURE || buf_getmpint(buf, key->q) == DROPBEAR_FAILURE || buf_getmpint(buf, key->g) == DROPBEAR_FAILURE || buf_getmpint(buf, key->y) == DROPBEAR_FAILURE) { TRACE(("leave buf_get_dss_pub_key: failed reading mpints")) return DROPBEAR_FAILURE; } if (mp_count_bits(key->p) < MIN_DSS_KEYLEN) { dropbear_log(LOG_WARNING, "DSS key too short"); TRACE(("leave buf_get_dss_pub_key: short key")) return DROPBEAR_FAILURE; } TRACE(("leave buf_get_dss_pub_key: success")) return DROPBEAR_SUCCESS; } /* Same as buf_get_dss_pub_key, but reads a private "x" key at the end. * Loads a private dss key from a buffer * Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ int buf_get_dss_priv_key(buffer* buf, dropbear_dss_key *key) { int ret = DROPBEAR_FAILURE; dropbear_assert(key != NULL); ret = buf_get_dss_pub_key(buf, key); if (ret == DROPBEAR_FAILURE) { return DROPBEAR_FAILURE; } m_mp_alloc_init_multi(&key->x, NULL); ret = buf_getmpint(buf, key->x); if (ret == DROPBEAR_FAILURE) { m_free(key->x); } return ret; } /* Clear and free the memory used by a public or private key */ void dss_key_free(dropbear_dss_key *key) { TRACE2(("enter dsa_key_free")) if (key == NULL) { TRACE2(("enter dsa_key_free: key == NULL")) return; } if (key->p) { mp_clear(key->p); m_free(key->p); } if (key->q) { mp_clear(key->q); m_free(key->q); } if (key->g) { mp_clear(key->g); m_free(key->g); } if (key->y) { mp_clear(key->y); m_free(key->y); } if (key->x) { mp_clear(key->x); m_free(key->x); } m_free(key); TRACE2(("leave dsa_key_free")) } /* put the dss public key into the buffer in the required format: * * string "ssh-dss" * mpint p * mpint q * mpint g * mpint y */ void buf_put_dss_pub_key(buffer* buf, dropbear_dss_key *key) { dropbear_assert(key != NULL); buf_putstring(buf, SSH_SIGNKEY_DSS, SSH_SIGNKEY_DSS_LEN); buf_putmpint(buf, key->p); buf_putmpint(buf, key->q); buf_putmpint(buf, key->g); buf_putmpint(buf, key->y); } /* Same as buf_put_dss_pub_key, but with the private "x" key appended */ void buf_put_dss_priv_key(buffer* buf, dropbear_dss_key *key) { dropbear_assert(key != NULL); buf_put_dss_pub_key(buf, key); buf_putmpint(buf, key->x); } #ifdef DROPBEAR_SIGNKEY_VERIFY /* Verify a DSS signature (in buf) made on data by the key given. * returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */ int buf_dss_verify(buffer* buf, dropbear_dss_key *key, buffer *data_buf) { unsigned char msghash[SHA1_HASH_SIZE]; hash_state hs; int ret = DROPBEAR_FAILURE; DEF_MP_INT(val1); DEF_MP_INT(val2); DEF_MP_INT(val3); DEF_MP_INT(val4); char * string = NULL; unsigned int stringlen; TRACE(("enter buf_dss_verify")) dropbear_assert(key != NULL); m_mp_init_multi(&val1, &val2, &val3, &val4, NULL); /* get blob, check length */ string = buf_getstring(buf, &stringlen); if (stringlen != 2*SHA1_HASH_SIZE) { goto out; } /* hash the data */ sha1_init(&hs); sha1_process(&hs, data_buf->data, data_buf->len); sha1_done(&hs, msghash); /* create the signature - s' and r' are the received signatures in buf */ /* w = (s')-1 mod q */ /* let val1 = s' */ bytes_to_mp(&val1, (const unsigned char*) &string[SHA1_HASH_SIZE], SHA1_HASH_SIZE); if (mp_cmp(&val1, key->q) != MP_LT) { TRACE(("verify failed, s' >= q")) goto out; } /* let val2 = w = (s')^-1 mod q*/ if (mp_invmod(&val1, key->q, &val2) != MP_OKAY) { goto out; } /* u1 = ((SHA(M')w) mod q */ /* let val1 = SHA(M') = msghash */ bytes_to_mp(&val1, msghash, SHA1_HASH_SIZE); /* let val3 = u1 = ((SHA(M')w) mod q */ if (mp_mulmod(&val1, &val2, key->q, &val3) != MP_OKAY) { goto out; } /* u2 = ((r')w) mod q */ /* let val1 = r' */ bytes_to_mp(&val1, (const unsigned char*) &string[0], SHA1_HASH_SIZE); if (mp_cmp(&val1, key->q) != MP_LT) { TRACE(("verify failed, r' >= q")) goto out; } /* let val4 = u2 = ((r')w) mod q */ if (mp_mulmod(&val1, &val2, key->q, &val4) != MP_OKAY) { goto out; } /* v = (((g)^u1 (y)^u2) mod p) mod q */ /* val2 = g^u1 mod p */ if (mp_exptmod(key->g, &val3, key->p, &val2) != MP_OKAY) { goto out; } /* val3 = y^u2 mod p */ if (mp_exptmod(key->y, &val4, key->p, &val3) != MP_OKAY) { goto out; } /* val4 = ((g)^u1 (y)^u2) mod p */ if (mp_mulmod(&val2, &val3, key->p, &val4) != MP_OKAY) { goto out; } /* val2 = v = (((g)^u1 (y)^u2) mod p) mod q */ if (mp_mod(&val4, key->q, &val2) != MP_OKAY) { goto out; } /* check whether signatures verify */ if (mp_cmp(&val2, &val1) == MP_EQ) { /* good sig */ ret = DROPBEAR_SUCCESS; } out: mp_clear_multi(&val1, &val2, &val3, &val4, NULL); m_free(string); return ret; } #endif /* DROPBEAR_SIGNKEY_VERIFY */ /* Sign the data presented with key, writing the signature contents * to the buffer */ void buf_put_dss_sign(buffer* buf, dropbear_dss_key *key, buffer *data_buf) { unsigned char msghash[SHA1_HASH_SIZE]; unsigned int writelen; unsigned int i; DEF_MP_INT(dss_k); DEF_MP_INT(dss_m); DEF_MP_INT(dss_temp1); DEF_MP_INT(dss_temp2); DEF_MP_INT(dss_r); DEF_MP_INT(dss_s); hash_state hs; TRACE(("enter buf_put_dss_sign")) dropbear_assert(key != NULL); /* hash the data */ sha1_init(&hs); sha1_process(&hs, data_buf->data, data_buf->len); sha1_done(&hs, msghash); m_mp_init_multi(&dss_k, &dss_temp1, &dss_temp2, &dss_r, &dss_s, &dss_m, NULL); /* the random number generator's input has included the private key which * avoids DSS's problem of private key exposure due to low entropy */ gen_random_mpint(key->q, &dss_k); /* now generate the actual signature */ bytes_to_mp(&dss_m, msghash, SHA1_HASH_SIZE); /* g^k mod p */ if (mp_exptmod(key->g, &dss_k, key->p, &dss_temp1) != MP_OKAY) { dropbear_exit("DSS error"); } /* r = (g^k mod p) mod q */ if (mp_mod(&dss_temp1, key->q, &dss_r) != MP_OKAY) { dropbear_exit("DSS error"); } /* x*r mod q */ if (mp_mulmod(&dss_r, key->x, key->q, &dss_temp1) != MP_OKAY) { dropbear_exit("DSS error"); } /* (SHA1(M) + xr) mod q) */ if (mp_addmod(&dss_m, &dss_temp1, key->q, &dss_temp2) != MP_OKAY) { dropbear_exit("DSS error"); } /* (k^-1) mod q */ if (mp_invmod(&dss_k, key->q, &dss_temp1) != MP_OKAY) { dropbear_exit("DSS error"); } /* s = (k^-1(SHA1(M) + xr)) mod q */ if (mp_mulmod(&dss_temp1, &dss_temp2, key->q, &dss_s) != MP_OKAY) { dropbear_exit("DSS error"); } buf_putstring(buf, SSH_SIGNKEY_DSS, SSH_SIGNKEY_DSS_LEN); buf_putint(buf, 2*SHA1_HASH_SIZE); writelen = mp_unsigned_bin_size(&dss_r); dropbear_assert(writelen <= SHA1_HASH_SIZE); /* need to pad to 160 bits with leading zeros */ for (i = 0; i < SHA1_HASH_SIZE - writelen; i++) { buf_putbyte(buf, 0); } if (mp_to_unsigned_bin(&dss_r, buf_getwriteptr(buf, writelen)) != MP_OKAY) { dropbear_exit("DSS error"); } mp_clear(&dss_r); buf_incrwritepos(buf, writelen); writelen = mp_unsigned_bin_size(&dss_s); dropbear_assert(writelen <= SHA1_HASH_SIZE); /* need to pad to 160 bits with leading zeros */ for (i = 0; i < SHA1_HASH_SIZE - writelen; i++) { buf_putbyte(buf, 0); } if (mp_to_unsigned_bin(&dss_s, buf_getwriteptr(buf, writelen)) != MP_OKAY) { dropbear_exit("DSS error"); } mp_clear(&dss_s); buf_incrwritepos(buf, writelen); mp_clear_multi(&dss_k, &dss_temp1, &dss_temp2, &dss_r, &dss_s, &dss_m, NULL); /* create the signature to return */ TRACE(("leave buf_put_dss_sign")) } #endif /* DROPBEAR_DSS */