Mercurial > dropbear
view libtomcrypt/src/pk/ecc/ecc_shared_secret.c @ 1930:299f4f19ba19
Add /usr/sbin and /sbin to default root PATH
When dropbear is used in a very restricted environment (such as in a
initrd), the default user shell is often also very restricted
and doesn't take care of setting the PATH so the user ends up
with the PATH set by dropbear. Unfortunately, dropbear always
sets "/usr/bin:/bin" as default PATH even for the root user
which should have /usr/sbin and /sbin too.
For a concrete instance of this problem, see the "Remote Unlocking"
section in this tutorial: https://paxswill.com/blog/2013/11/04/encrypted-raspberry-pi/
It speaks of a bug in the initramfs script because it's written "blkid"
instead of "/sbin/blkid"... this is just because the scripts from the
initramfs do not expect to have a PATH without the sbin directories and
because dropbear is not setting the PATH appropriately for the root user.
I'm thus suggesting to use the attached patch to fix this misbehaviour (I
did not test it, but it's easy enough). It might seem anecdotic but
multiple Kali users have been bitten by this.
From https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
author | Raphael Hertzog <hertzog@debian.org> |
---|---|
date | Mon, 09 Jul 2018 16:27:53 +0200 |
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. */ /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b * * All curves taken from NIST recommendation paper of July 1999 * Available at http://csrc.nist.gov/cryptval/dss.htm */ #include "tomcrypt.h" /** @file ecc_shared_secret.c ECC Crypto, Tom St Denis */ #ifdef LTC_MECC /** Create an ECC shared secret between two keys @param private_key The private ECC key @param public_key The public key @param out [out] Destination of the shared secret (Conforms to EC-DH from ANSI X9.63) @param outlen [in/out] The max size and resulting size of the shared secret @return CRYPT_OK if successful */ int ecc_shared_secret(ecc_key *private_key, ecc_key *public_key, unsigned char *out, unsigned long *outlen) { unsigned long x; ecc_point *result; void *prime; int err; LTC_ARGCHK(private_key != NULL); LTC_ARGCHK(public_key != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); /* type valid? */ if (private_key->type != PK_PRIVATE) { return CRYPT_PK_NOT_PRIVATE; } if (ltc_ecc_is_valid_idx(private_key->idx) == 0 || ltc_ecc_is_valid_idx(public_key->idx) == 0) { return CRYPT_INVALID_ARG; } if (XSTRCMP(private_key->dp->name, public_key->dp->name) != 0) { return CRYPT_PK_TYPE_MISMATCH; } /* make new point */ result = ltc_ecc_new_point(); if (result == NULL) { return CRYPT_MEM; } if ((err = mp_init(&prime)) != CRYPT_OK) { ltc_ecc_del_point(result); return err; } if ((err = mp_read_radix(prime, (char *)private_key->dp->prime, 16)) != CRYPT_OK) { goto done; } if ((err = ltc_mp.ecc_ptmul(private_key->k, &public_key->pubkey, result, prime, 1)) != CRYPT_OK) { goto done; } x = (unsigned long)mp_unsigned_bin_size(prime); if (*outlen < x) { *outlen = x; err = CRYPT_BUFFER_OVERFLOW; goto done; } zeromem(out, x); if ((err = mp_to_unsigned_bin(result->x, out + (x - mp_unsigned_bin_size(result->x)))) != CRYPT_OK) { goto done; } err = CRYPT_OK; *outlen = x; done: mp_clear(prime); ltc_ecc_del_point(result); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */