Mercurial > dropbear
annotate libtommath/bn_mp_div_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> |
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date | Mon, 09 Jul 2018 16:27:53 +0200 |
parents | 1051e4eea25a |
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rev | line source |
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update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
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1 #include "tommath_private.h" |
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2 #ifdef BN_MP_DIV_2_C |
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3 /* LibTomMath, multiple-precision integer library -- Tom St Denis */ |
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4 /* SPDX-License-Identifier: Unlicense */ |
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5 |
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6 /* b = a/2 */ |
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7 mp_err mp_div_2(const mp_int *a, mp_int *b) |
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8 { |
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9 int x, oldused; |
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10 mp_digit r, rr, *tmpa, *tmpb; |
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11 mp_err err; |
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12 |
1655
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13 /* copy */ |
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14 if (b->alloc < a->used) { |
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15 if ((err = mp_grow(b, a->used)) != MP_OKAY) { |
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16 return err; |
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17 } |
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18 } |
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19 |
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20 oldused = b->used; |
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21 b->used = a->used; |
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22 |
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23 /* source alias */ |
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24 tmpa = a->dp + b->used - 1; |
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25 |
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26 /* dest alias */ |
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27 tmpb = b->dp + b->used - 1; |
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28 |
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29 /* carry */ |
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30 r = 0; |
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31 for (x = b->used - 1; x >= 0; x--) { |
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32 /* get the carry for the next iteration */ |
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33 rr = *tmpa & 1u; |
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34 |
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35 /* shift the current digit, add in carry and store */ |
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36 *tmpb-- = (*tmpa-- >> 1) | (r << (MP_DIGIT_BIT - 1)); |
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37 |
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38 /* forward carry to next iteration */ |
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39 r = rr; |
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40 } |
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41 |
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42 /* zero excess digits */ |
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43 MP_ZERO_DIGITS(b->dp + b->used, oldused - b->used); |
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44 |
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45 b->sign = a->sign; |
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46 mp_clamp(b); |
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47 return MP_OKAY; |
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48 } |
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49 #endif |