view crypto_desc.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 3f4cdf839a1a
children
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#include "includes.h"
#include "dbutil.h"
#include "crypto_desc.h"
#include "ltc_prng.h"
#include "ecc.h"
#include "dbrandom.h"

#if DROPBEAR_LTC_PRNG
	int dropbear_ltc_prng = -1;
#endif

/* Wrapper for libtommath */
static mp_err dropbear_rand_source(void* out, size_t size) {
	genrandom((unsigned char*)out, (unsigned int)size);
	return MP_OKAY;
}


/* Register the compiled in ciphers.
 * This should be run before using any of the ciphers/hashes */
void crypto_init() {

	const struct ltc_cipher_descriptor *regciphers[] = {
#if DROPBEAR_AES
		&aes_desc,
#endif
#if DROPBEAR_3DES
		&des3_desc,
#endif
		NULL
	};

	const struct ltc_hash_descriptor *reghashes[] = {
#if DROPBEAR_SHA1_HMAC
		&sha1_desc,
#endif
#if DROPBEAR_MD5_HMAC
		&md5_desc,
#endif
#if DROPBEAR_SHA256
		&sha256_desc,
#endif
#if DROPBEAR_SHA384
		&sha384_desc,
#endif
#if DROPBEAR_SHA512
		&sha512_desc,
#endif
		NULL
	};
	int i;

	for (i = 0; regciphers[i] != NULL; i++) {
		if (register_cipher(regciphers[i]) == -1) {
			dropbear_exit("Error registering crypto");
		}
	}

	for (i = 0; reghashes[i] != NULL; i++) {
		if (register_hash(reghashes[i]) == -1) {
			dropbear_exit("Error registering crypto");
		}
	}

#if DROPBEAR_LTC_PRNG
	dropbear_ltc_prng = register_prng(&dropbear_prng_desc);
	if (dropbear_ltc_prng == -1) {
		dropbear_exit("Error registering crypto");
	}
#endif

	mp_rand_source(dropbear_rand_source);

#if DROPBEAR_ECC
	ltc_mp = ltm_desc;
	dropbear_ecc_fill_dp();
#endif
}