Mercurial > dropbear
view libtomcrypt/src/misc/pkcs5/pkcs_5_2.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_5_2.c PKCS #5, Algorithm #2, Tom St Denis */ #ifdef LTC_PKCS_5 /** Execute PKCS #5 v2 @param password The input password (or key) @param password_len The length of the password (octets) @param salt The salt (or nonce) @param salt_len The length of the salt (octets) @param iteration_count # of iterations desired for PKCS #5 v2 [read specs for more] @param hash_idx The index of the hash desired @param out [out] The destination for this algorithm @param outlen [in/out] The max size and resulting size of the algorithm output @return CRYPT_OK if successful */ int pkcs_5_alg2(const unsigned char *password, unsigned long password_len, const unsigned char *salt, unsigned long salt_len, int iteration_count, int hash_idx, unsigned char *out, unsigned long *outlen) { int err, itts; ulong32 blkno; unsigned long stored, left, x, y; unsigned char *buf[2]; hmac_state *hmac; LTC_ARGCHK(password != NULL); LTC_ARGCHK(salt != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); /* test hash IDX */ if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { return err; } buf[0] = XMALLOC(MAXBLOCKSIZE * 2); hmac = XMALLOC(sizeof(hmac_state)); if (hmac == NULL || buf[0] == NULL) { if (hmac != NULL) { XFREE(hmac); } if (buf[0] != NULL) { XFREE(buf[0]); } return CRYPT_MEM; } /* buf[1] points to the second block of MAXBLOCKSIZE bytes */ buf[1] = buf[0] + MAXBLOCKSIZE; left = *outlen; blkno = 1; stored = 0; while (left != 0) { /* process block number blkno */ zeromem(buf[0], MAXBLOCKSIZE*2); /* store current block number and increment for next pass */ STORE32H(blkno, buf[1]); ++blkno; /* get PRF(P, S||int(blkno)) */ if ((err = hmac_init(hmac, hash_idx, password, password_len)) != CRYPT_OK) { goto LBL_ERR; } if ((err = hmac_process(hmac, salt, salt_len)) != CRYPT_OK) { goto LBL_ERR; } if ((err = hmac_process(hmac, buf[1], 4)) != CRYPT_OK) { goto LBL_ERR; } x = MAXBLOCKSIZE; if ((err = hmac_done(hmac, buf[0], &x)) != CRYPT_OK) { goto LBL_ERR; } /* now compute repeated and XOR it in buf[1] */ XMEMCPY(buf[1], buf[0], x); for (itts = 1; itts < iteration_count; ++itts) { if ((err = hmac_memory(hash_idx, password, password_len, buf[0], x, buf[0], &x)) != CRYPT_OK) { goto LBL_ERR; } for (y = 0; y < x; y++) { buf[1][y] ^= buf[0][y]; } } /* now emit upto x bytes of buf[1] to output */ for (y = 0; y < x && left != 0; ++y) { out[stored++] = buf[1][y]; --left; } } *outlen = stored; err = CRYPT_OK; LBL_ERR: #ifdef LTC_CLEAN_STACK zeromem(buf[0], MAXBLOCKSIZE*2); zeromem(hmac, sizeof(hmac_state)); #endif XFREE(hmac); XFREE(buf[0]); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */