Mercurial > dropbear
view libtomcrypt/src/encauth/ocb/s_ocb_done.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. */ /** @file s_ocb_done.c OCB implementation, internal helper, by Tom St Denis */ #include "tomcrypt.h" #ifdef LTC_OCB_MODE /* Since the last block is encrypted in CTR mode the same code can * be used to finish a decrypt or encrypt stream. The only difference * is we XOR the final ciphertext into the checksum so we have to xor it * before we CTR [decrypt] or after [encrypt] * * the names pt/ptlen/ct really just mean in/inlen/out but this is the way I wrote it... */ /** Shared code to finish an OCB stream @param ocb The OCB state @param pt The remaining plaintext [or input] @param ptlen The length of the input (octets) @param ct [out] The output buffer @param tag [out] The destination for the authentication tag @param taglen [in/out] The max size and resulting size of the authentication tag @param mode The mode we are terminating, 0==encrypt, 1==decrypt @return CRYPT_OK if successful */ int s_ocb_done(ocb_state *ocb, const unsigned char *pt, unsigned long ptlen, unsigned char *ct, unsigned char *tag, unsigned long *taglen, int mode) { unsigned char *Z, *Y, *X; int err, x; LTC_ARGCHK(ocb != NULL); LTC_ARGCHK(pt != NULL); LTC_ARGCHK(ct != NULL); LTC_ARGCHK(tag != NULL); LTC_ARGCHK(taglen != NULL); if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) { return err; } if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length || (int)ptlen > ocb->block_len || (int)ptlen < 0) { return CRYPT_INVALID_ARG; } /* allocate ram */ Z = XMALLOC(MAXBLOCKSIZE); Y = XMALLOC(MAXBLOCKSIZE); X = XMALLOC(MAXBLOCKSIZE); if (X == NULL || Y == NULL || Z == NULL) { if (X != NULL) { XFREE(X); } if (Y != NULL) { XFREE(Y); } if (Z != NULL) { XFREE(Z); } return CRYPT_MEM; } /* compute X[m] = len(pt[m]) XOR Lr XOR Z[m] */ ocb_shift_xor(ocb, X); XMEMCPY(Z, X, ocb->block_len); X[ocb->block_len-1] ^= (ptlen*8)&255; X[ocb->block_len-2] ^= ((ptlen*8)>>8)&255; for (x = 0; x < ocb->block_len; x++) { X[x] ^= ocb->Lr[x]; } /* Y[m] = E(X[m])) */ if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(X, Y, &ocb->key)) != CRYPT_OK) { goto error; } if (mode == 1) { /* decrypt mode, so let's xor it first */ /* xor C[m] into checksum */ for (x = 0; x < (int)ptlen; x++) { ocb->checksum[x] ^= ct[x]; } } /* C[m] = P[m] xor Y[m] */ for (x = 0; x < (int)ptlen; x++) { ct[x] = pt[x] ^ Y[x]; } if (mode == 0) { /* encrypt mode */ /* xor C[m] into checksum */ for (x = 0; x < (int)ptlen; x++) { ocb->checksum[x] ^= ct[x]; } } /* xor Y[m] and Z[m] into checksum */ for (x = 0; x < ocb->block_len; x++) { ocb->checksum[x] ^= Y[x] ^ Z[x]; } /* encrypt checksum, er... tag!! */ if ((err = cipher_descriptor[ocb->cipher].ecb_encrypt(ocb->checksum, X, &ocb->key)) != CRYPT_OK) { goto error; } cipher_descriptor[ocb->cipher].done(&ocb->key); /* now store it */ for (x = 0; x < ocb->block_len && x < (int)*taglen; x++) { tag[x] = X[x]; } *taglen = x; #ifdef LTC_CLEAN_STACK zeromem(X, MAXBLOCKSIZE); zeromem(Y, MAXBLOCKSIZE); zeromem(Z, MAXBLOCKSIZE); zeromem(ocb, sizeof(*ocb)); #endif error: XFREE(X); XFREE(Y); XFREE(Z); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */