Mercurial > dropbear
view libtomcrypt/src/pk/pkcs1/pkcs_1_v1_5_encode.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. */ #include "tomcrypt.h" /*! \file pkcs_1_v1_5_encode.c * * PKCS #1 v1.5 Padding (Andreas Lange) */ #ifdef LTC_PKCS_1 /*! \brief PKCS #1 v1.5 encode. * * \param msg The data to encode * \param msglen The length of the data to encode (octets) * \param block_type Block type to use in padding (\sa ltc_pkcs_1_v1_5_blocks) * \param modulus_bitlen The bit length of the RSA modulus * \param prng An active PRNG state (only for LTC_PKCS_1_EME) * \param prng_idx The index of the PRNG desired (only for LTC_PKCS_1_EME) * \param out [out] The destination for the encoded data * \param outlen [in/out] The max size and resulting size of the encoded data * * \return CRYPT_OK if successful */ int pkcs_1_v1_5_encode(const unsigned char *msg, unsigned long msglen, int block_type, unsigned long modulus_bitlen, prng_state *prng, int prng_idx, unsigned char *out, unsigned long *outlen) { unsigned long modulus_len, ps_len, i; unsigned char *ps; int result; /* valid block_type? */ if ((block_type != LTC_PKCS_1_EMSA) && (block_type != LTC_PKCS_1_EME)) { return CRYPT_PK_INVALID_PADDING; } if (block_type == LTC_PKCS_1_EME) { /* encryption padding, we need a valid PRNG */ if ((result = prng_is_valid(prng_idx)) != CRYPT_OK) { return result; } } modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); /* test message size */ if ((msglen + 11) > modulus_len) { return CRYPT_PK_INVALID_SIZE; } if (*outlen < modulus_len) { *outlen = modulus_len; result = CRYPT_BUFFER_OVERFLOW; goto bail; } /* generate an octets string PS */ ps = &out[2]; ps_len = modulus_len - msglen - 3; if (block_type == LTC_PKCS_1_EME) { /* now choose a random ps */ if (prng_descriptor[prng_idx].read(ps, ps_len, prng) != ps_len) { result = CRYPT_ERROR_READPRNG; goto bail; } /* transform zero bytes (if any) to non-zero random bytes */ for (i = 0; i < ps_len; i++) { while (ps[i] == 0) { if (prng_descriptor[prng_idx].read(&ps[i], 1, prng) != 1) { result = CRYPT_ERROR_READPRNG; goto bail; } } } } else { XMEMSET(ps, 0xFF, ps_len); } /* create string of length modulus_len */ out[0] = 0x00; out[1] = (unsigned char)block_type; /* block_type 1 or 2 */ out[2 + ps_len] = 0x00; XMEMCPY(&out[2 + ps_len + 1], msg, msglen); *outlen = modulus_len; result = CRYPT_OK; bail: return result; } /* pkcs_1_v1_5_encode */ #endif /* #ifdef LTC_PKCS_1 */ /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */