| 1 | |
| 2 | * random.c -- A strong random number generator
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| 3 | *
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| 4 | * Copyright Matt Mackall <[email protected]>, 2003, 2004, 2005
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| 5 | *
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| 6 | * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
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| 7 | * rights reserved.
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| 8 | *
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| 9 | * Redistribution and use in source and binary forms, with or without
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| 10 | * modification, are permitted provided that the following conditions
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| 11 | * are met:
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| 12 | * 1. Redistributions of source code must retain the above copyright
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| 13 | * notice, and the entire permission notice in its entirety,
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| 14 | * including the disclaimer of warranties.
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| 15 | * 2. Redistributions in binary form must reproduce the above copyright
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| 16 | * notice, this list of conditions and the following disclaimer in the
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| 17 | * documentation and/or other materials provided with the distribution.
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| 18 | * 3. The name of the author may not be used to endorse or promote
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| 19 | * products derived from this software without specific prior
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| 20 | * written permission.
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| 21 | *
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| 22 | * ALTERNATIVELY, this product may be distributed under the terms of
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| 23 | * the GNU General Public License, in which case the provisions of the GPL are
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| 24 | * required INSTEAD OF the above restrictions. (This clause is
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| 25 | * necessary due to a potential bad interaction between the GPL and
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| 26 | * the restrictions contained in a BSD-style copyright.)
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| 27 | *
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| 28 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 29 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 30 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
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| 31 | * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
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| 32 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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| 33 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 34 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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| 35 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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| 36 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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| 38 | * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
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| 39 | * DAMAGE.
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| 40 |
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| 41 |
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| 42 | |
| 43 | * (now, with legal B.S. out of the way.....)
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| 44 | *
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| 45 | * This routine gathers environmental noise from device drivers, etc.,
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| 46 | * and returns good random numbers, suitable for cryptographic use.
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| 47 | * Besides the obvious cryptographic uses, these numbers are also good
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| 48 | * for seeding TCP sequence numbers, and other places where it is
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| 49 | * desirable to have numbers which are not only random, but hard to
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| 50 | * predict by an attacker.
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| 51 | *
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| 52 | * Theory of operation
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| 53 | * ===================
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| 54 | *
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| 55 | * Computers are very predictable devices. Hence it is extremely hard
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| 56 | * to produce truly random numbers on a computer --- as opposed to
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| 57 | * pseudo-random numbers, which can easily generated by using a
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| 58 | * algorithm. Unfortunately, it is very easy for attackers to guess
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| 59 | * the sequence of pseudo-random number generators, and for some
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| 60 | * applications this is not acceptable. So instead, we must try to
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| 61 | * gather "environmental noise" from the computer's environment, which
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| 62 | * must be hard for outside attackers to observe, and use that to
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| 63 | * generate random numbers. In a Unix environment, this is best done
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| 64 | * from inside the kernel.
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| 65 | *
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| 66 | * Sources of randomness from the environment include inter-keyboard
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| 67 | * timings, inter-interrupt timings from some interrupts, and other
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| 68 | * events which are both (a) non-deterministic and (b) hard for an
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| 69 | * outside observer to measure. Randomness from these sources are
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| 70 | * added to an "entropy pool", which is mixed using a CRC-like function.
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| 71 | * This is not cryptographically strong, but it is adequate assuming
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| 72 | * the randomness is not chosen maliciously, and it is fast enough that
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| 73 | * the overhead of doing it on every interrupt is very reasonable.
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| 74 | * As random bytes are mixed into the entropy pool, the routines keep
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| 75 | * an *estimate* of how many bits of randomness have been stored into
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| 76 | * the random number generator's internal state.
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| 77 | *
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| 78 | * When random bytes are desired, they are obtained by taking the SHA
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| 79 | * hash of the contents of the "entropy pool". The SHA hash avoids
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| 80 | * exposing the internal state of the entropy pool. It is believed to
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| 81 | * be computationally infeasible to derive any useful information
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| 82 | * about the input of SHA from its output. Even if it is possible to
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| 83 | * analyze SHA in some clever way, as long as the amount of data
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| 84 | * returned from the generator is less than the inherent entropy in
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| 85 | * the pool, the output data is totally unpredictable. For this
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| 86 | * reason, the routine decreases its internal estimate of how many
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| 87 | * bits of "true randomness" are contained in the entropy pool as it
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| 88 | * outputs random numbers.
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| 89 | *
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| 90 | * If this estimate goes to zero, the routine can still generate
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| 91 | * random numbers; however, an attacker may (at least in theory) be
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| 92 | * able to infer the future output of the generator from prior
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| 93 | * outputs. This requires successful cryptanalysis of SHA, which is
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| 94 | * not believed to be feasible, but there is a remote possibility.
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| 95 | * Nonetheless, these numbers should be useful for the vast majority
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| 96 | * of purposes.
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| 97 | *
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| 98 | * Exported interfaces ---- output
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| 99 | * ===============================
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| 100 | *
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| 101 | * There are three exported interfaces; the first is one designed to
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| 102 | * be used from within the kernel:
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| 103 | *
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| 104 | * void get_random_bytes(void *buf, int nbytes);
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| 105 | *
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| 106 | * This interface will return the requested number of random bytes,
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| 107 | * and place it in the requested buffer.
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| 108 | *
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| 109 | * The two other interfaces are two character devices /dev/random and
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| 110 | * /dev/urandom. /dev/random is suitable for use when very high
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| 111 | * quality randomness is desired (for example, for key generation or
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| 112 | * one-time pads), as it will only return a maximum of the number of
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| 113 | * bits of randomness (as estimated by the random number generator)
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| 114 | * contained in the entropy pool.
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| 115 | *
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| 116 | * The /dev/urandom device does not have this limit, and will return
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| 117 | * as many bytes as are requested. As more and more random bytes are
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| 118 | * requested without giving time for the entropy pool to recharge,
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| 119 | * this will result in random numbers that are merely cryptographically
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| 120 | * strong. For many applications, however, this is acceptable.
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| 121 | *
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| 122 | * Exported interfaces ---- input
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| 123 | * ==============================
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| 124 | *
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| 125 | * The current exported interfaces for gathering environmental noise
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| 126 | * from the devices are:
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| 127 | *
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| 128 | * void add_input_randomness(unsigned int type, unsigned int code,
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| 129 | * unsigned int value);
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| 130 | * void add_interrupt_randomness(int irq);
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| 131 | *
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| 132 | * add_input_randomness() uses the input layer interrupt timing, as well as
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| 133 | * the event type information from the hardware.
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| 134 | *
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| 135 | * add_interrupt_randomness() uses the inter-interrupt timing as random
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| 136 | * inputs to the entropy pool. Note that not all interrupts are good
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| 137 | * sources of randomness! For example, the timer interrupts is not a
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| 138 | * good choice, because the periodicity of the interrupts is too
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| 139 | * regular, and hence predictable to an attacker. Disk interrupts are
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| 140 | * a better measure, since the timing of the disk interrupts are more
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| 141 | * unpredictable.
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| 142 | *
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| 143 | * All of these routines try to estimate how many bits of randomness a
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| 144 | * particular randomness source. They do this by keeping track of the
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| 145 | * first and second order deltas of the event timings.
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| 146 | *
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| 147 | * Ensuring unpredictability at system startup
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| 148 | * ============================================
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| 149 | *
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| 150 | * When any operating system starts up, it will go through a sequence
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| 151 | * of actions that are fairly predictable by an adversary, especially
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| 152 | * if the start-up does not involve interaction with a human operator.
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| 153 | * This reduces the actual number of bits of unpredictability in the
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| 154 | * entropy pool below the value in entropy_count. In order to
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| 155 | * counteract this effect, it helps to carry information in the
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| 156 | * entropy pool across shut-downs and start-ups. To do this, put the
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| 157 | * following lines an appropriate script which is run during the boot
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| 158 | * sequence:
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| 159 | *
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| 160 | * echo "Initializing random number generator..."
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| 161 | * random_seed=/var/run/random-seed
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| 162 | * # Carry a random seed from start-up to start-up
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| 163 | * # Load and then save the whole entropy pool
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| 164 | * if [ -f $random_seed ]; then
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| 165 | * cat $random_seed >/dev/urandom
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| 166 | * else
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| 167 | * touch $random_seed
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| 168 | * fi
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| 169 | * chmod 600 $random_seed
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| 170 | * dd if=/dev/urandom of=$random_seed count=1 bs=512
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| 171 | *
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| 172 | * and the following lines in an appropriate script which is run as
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| 173 | * the system is shutdown:
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| 174 | *
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| 175 | * # Carry a random seed from shut-down to start-up
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| 176 | * # Save the whole entropy pool
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| 177 | * echo "Saving random seed..."
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| 178 | * random_seed=/var/run/random-seed
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| 179 | * touch $random_seed
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| 180 | * chmod 600 $random_seed
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| 181 | * dd if=/dev/urandom of=$random_seed count=1 bs=512
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| 182 | *
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| 183 | * For example, on most modern systems using the System V init
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| 184 | * scripts, such code fragments would be found in
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| 185 | * /etc/rc.d/init.d/random. On older Linux systems, the correct script
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| 186 | * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
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| 187 | *
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| 188 | * Effectively, these commands cause the contents of the entropy pool
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| 189 | * to be saved at shut-down time and reloaded into the entropy pool at
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| 190 | * start-up. (The 'dd' in the addition to the bootup script is to
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| 191 | * make sure that /etc/random-seed is different for every start-up,
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| 192 | * even if the system crashes without executing rc.0.) Even with
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| 193 | * complete knowledge of the start-up activities, predicting the state
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| 194 | * of the entropy pool requires knowledge of the previous history of
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| 195 | * the system.
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| 196 | *
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| 197 | * Configuring the /dev/random driver under Linux
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| 198 | * ==============================================
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| 199 | *
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| 200 | * The /dev/random driver under Linux uses minor numbers 8 and 9 of
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| 201 | * the /dev/mem major number (#1). So if your system does not have
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| 202 | * /dev/random and /dev/urandom created already, they can be created
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| 203 | * by using the commands:
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| 204 | *
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| 205 | * mknod /dev/random c 1 8
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| 206 | * mknod /dev/urandom c 1 9
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| 207 | *
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| 208 | * Acknowledgements:
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| 209 | * =================
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| 210 | *
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| 211 | * Ideas for constructing this random number generator were derived
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| 212 | * from Pretty Good Privacy's random number generator, and from private
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| 213 | * discussions with Phil Karn. Colin Plumb provided a faster random
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| 214 | * number generator, which speed up the mixing function of the entropy
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| 215 | * pool, taken from PGPfone. Dale Worley has also contributed many
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| 216 | * useful ideas and suggestions to improve this driver.
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| 217 | *
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| 218 | * Any flaws in the design are solely my responsibility, and should
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| 219 | * not be attributed to the Phil, Colin, or any of authors of PGP.
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| 220 | *
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| 221 | * Further background information on this topic may be obtained from
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| 222 | * RFC 1750, "Randomness Recommendations for Security", by Donald
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| 223 | * Eastlake, Steve Crocker, and Jeff Schiller.
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| 224 |
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| 225 |
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| 226 | #include <linux/utsname.h>
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| 227 | #include <linux/module.h>
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| 228 | #include <linux/kernel.h>
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| 229 | #include <linux/major.h>
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| 230 | #include <linux/string.h>
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| 231 | #include <linux/fcntl.h>
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| 232 | #include <linux/slab.h>
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| 233 | #include <linux/random.h>
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| 234 | #include <linux/poll.h>
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| 235 | #include <linux/init.h>
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| 236 | #include <linux/fs.h>
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| 237 | #include <linux/genhd.h>
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| 238 | #include <linux/interrupt.h>
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| 239 | #include <linux/spinlock.h>
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| 240 | #include <linux/percpu.h>
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| 241 | #include <linux/cryptohash.h>
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| 242 |
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| 243 | #include <asm/processor.h>
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| 244 | #include <asm/uaccess.h>
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| 245 | #include <asm/irq.h>
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| 246 | #include <asm/io.h>
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| 247 |
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| 248 | |
| 249 | * Configuration information
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| 250 |
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| 251 | #define INPUT_POOL_WORDS 128
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| 252 | #define OUTPUT_POOL_WORDS 32
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| 253 | #define SEC_XFER_SIZE 512
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| 254 |
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| 255 | |
| 256 | * The minimum number of bits of entropy before we wake up a read on
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| 257 | * /dev/random. Should be enough to do a significant reseed.
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| 258 |
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| 259 | static int random_read_wakeup_thresh = 64;
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| 260 |
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| 261 | |
| 262 | * If the entropy count falls under this number of bits, then we
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| 263 | * should wake up processes which are selecting or polling on write
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| 264 | * access to /dev/random.
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| 265 |
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| 266 | static int random_write_wakeup_thresh = 128;
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| 267 |
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| 268 | |
| 269 | * When the input pool goes over trickle_thresh, start dropping most
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| 270 | * samples to avoid wasting CPU time and reduce lock contention.
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| 271 |
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| 272 |
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| 273 | static int trickle_thresh __read_mostly = INPUT_POOL_WORDS * 28;
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| 274 |
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| 275 | static DEFINE_PER_CPU(int, trickle_count) = 0;
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| 276 |
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| 277 | |
| 278 | * A pool of size .poolwords is stirred with a primitive polynomial
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| 279 | * of degree .poolwords over GF(2). The taps for various sizes are
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| 280 | * defined below. They are chosen to be evenly spaced (minimum RMS
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| 281 | * distance from evenly spaced; the numbers in the comments are a
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| 282 | * scaled squared error sum) except for the last tap, which is 1 to
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| 283 | * get the twisting happening as fast as possible.
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| 284 |
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| 285 | static struct poolinfo {
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| 286 | int poolwords;
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| 287 | int tap1, tap2, tap3, tap4, tap5;
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| 288 | } poolinfo_table[] = {
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| 289 |
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| 290 | { 128, 103, 76, 51, 25, 1 },
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| 291 |
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| 292 | { 32, 26, 20, 14, 7, 1 },
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| 293 | #if 0 |
| 294 | /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1 -- 115 */
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| 295 | { 2048, 1638, 1231, 819, 411, 1 },
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| 296 |
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| 297 | /* x^1024 + x^817 + x^615 + x^412 + x^204 + x + 1 -- 290 */
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| 298 | { 1024, 817, 615, 412, 204, 1 },
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| 299 |
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| 300 | /* x^1024 + x^819 + x^616 + x^410 + x^207 + x^2 + 1 -- 115 */
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| 301 | { 1024, 819, 616, 410, 207, 2 },
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| 302 |
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| 303 | /* x^512 + x^411 + x^308 + x^208 + x^104 + x + 1 -- 225 */
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| 304 | { 512, 411, 308, 208, 104, 1 },
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| 305 |
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| 306 | /* x^512 + x^409 + x^307 + x^206 + x^102 + x^2 + 1 -- 95 */
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| 307 | { 512, 409, 307, 206, 102, 2 },
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| 308 | /* x^512 + x^409 + x^309 + x^205 + x^103 + x^2 + 1 -- 95 */
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| 309 | { 512, 409, 309, 205, 103, 2 },
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| 310 |
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| 311 | /* x^256 + x^205 + x^155 + x^101 + x^52 + x + 1 -- 125 */
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| 312 | { 256, 205, 155, 101, 52, 1 },
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| 313 |
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| 314 | /* x^128 + x^103 + x^78 + x^51 + x^27 + x^2 + 1 -- 70 */
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| 315 | { 128, 103, 78, 51, 27, 2 },
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| 316 |
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| 317 | /* x^64 + x^52 + x^39 + x^26 + x^14 + x + 1 -- 15 */
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| 318 | { 64, 52, 39, 26, 14, 1 },
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| 319 | #endif
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| 320 | };
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| 321 |
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| 322 | #define POOLBITS poolwords*32
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| 323 | #define POOLBYTES poolwords*4
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| 324 |
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| 325 | |
| 326 | * For the purposes of better mixing, we use the CRC-32 polynomial as
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| 327 | * well to make a twisted Generalized Feedback Shift Reigster
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| 328 | *
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| 329 | * (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR generators. ACM
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| 330 | * Transactions on Modeling and Computer Simulation 2(3):179-194.
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| 331 | * Also see M. Matsumoto & Y. Kurita, 1994. Twisted GFSR generators
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| 332 | * II. ACM Transactions on Mdeling and Computer Simulation 4:254-266)
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| 333 | *
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| 334 | * Thanks to Colin Plumb for suggesting this.
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| 335 | *
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| 336 | * We have not analyzed the resultant polynomial to prove it primitive;
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| 337 | * in fact it almost certainly isn't. Nonetheless, the irreducible factors
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| 338 | * of a random large-degree polynomial over GF(2) are more than large enough
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| 339 | * that periodicity is not a concern.
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| 340 | *
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| 341 | * The input hash is much less sensitive than the output hash. All
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| 342 | * that we want of it is that it be a good non-cryptographic hash;
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| 343 | * i.e. it not produce collisions when fed "random" data of the sort
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| 344 | * we expect to see. As long as the pool state differs for different
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| 345 | * inputs, we have preserved the input entropy and done a good job.
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| 346 | * The fact that an intelligent attacker can construct inputs that
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| 347 | * will produce controlled alterations to the pool's state is not
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| 348 | * important because we don't consider such inputs to contribute any
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| 349 | * randomness. The only property we need with respect to them is that
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| 350 | * the attacker can't increase his/her knowledge of the pool's state.
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| 351 | * Since all additions are reversible (knowing the final state and the
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| 352 | * input, you can reconstruct the initial state), if an attacker has
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| 353 | * any uncertainty about the initial state, he/she can only shuffle
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| 354 | * that uncertainty about, but never cause any collisions (which would
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| 355 | * decrease the uncertainty).
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| 356 | *
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| 357 | * The chosen system lets the state of the pool be (essentially) the input
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| 358 | * modulo the generator polymnomial. Now, for random primitive polynomials,
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| 359 | * this is a universal class of hash functions, meaning that the chance
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| 360 | * of a collision is limited by the attacker's knowledge of the generator
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| 361 | * polynomail, so if it is chosen at random, an attacker can never force
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| 362 | * a collision. Here, we use a fixed polynomial, but we *can* assume that
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| 363 | * ###--> it is unknown to the processes generating the input entropy. <-###
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| 364 | * Because of this important property, this is a good, collision-resistant
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| 365 | * hash; hash collisions will occur no more often than chance.
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| 366 |
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| 367 |
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| 368 | |
| 369 | * Static global variables
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| 370 |
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| 371 | static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
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| 372 | static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
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| 373 |
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| 374 | #if 0 |
| 375 | static int debug = 0;
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| 376 | module_param(debug, bool, 0644);
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| 377 | #define DEBUG_ENT(fmt, arg...) do { if (debug) \
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| 378 | printk(KERN_DEBUG "random %04d %04d %04d: " \
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| 379 | fmt,\
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| 380 | input_pool.entropy_count,\
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| 381 | blocking_pool.entropy_count,\
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| 382 | nonblocking_pool.entropy_count,\
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| 383 | ## arg); } while (0)
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| 384 | #else
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| 385 | #define DEBUG_ENT(fmt, arg...) do {} while (0)
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| 386 | #endif
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| 387 |
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| 388 | |
| 389 | *
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| 390 | * OS independent entropy store. Here are the functions which handle
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| 391 | * storing entropy in an entropy pool.
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| 392 | *
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| 393 | *********************************************************************
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| 394 |
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| 395 | struct entropy_store;
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| 396 | struct entropy_store {
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| 397 |
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| 398 | struct poolinfo *poolinfo;
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| 399 | __u32 *pool;
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| 400 | const char *name;
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| 401 | int limit;
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| 402 | struct entropy_store *pull;
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| 403 |
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| 404 |
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| 405 | spinlock_t lock ____cacheline_aligned_in_smp;
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| 406 | unsigned add_ptr;
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| 407 | int entropy_count;
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| 408 | int input_rotate;
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| 409 | };
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| 410 |
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| 411 | static __u32 input_pool_data[INPUT_POOL_WORDS];
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| 412 | static __u32 blocking_pool_data[OUTPUT_POOL_WORDS];
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| 413 | static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS];
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| 414 |
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| 415 | static struct entropy_store input_pool = {
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| 416 | .poolinfo = &poolinfo_table[0],
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| 417 | .name = "input",
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| 418 | .limit = 1,
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| 419 | .lock = __SPIN_LOCK_UNLOCKED(&input_pool.lock),
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| 420 | .pool = input_pool_data
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| 421 | };
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| 422 |
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| 423 | static struct entropy_store blocking_pool = {
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| 424 | .poolinfo = &poolinfo_table[1],
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| 425 | .name = "blocking",
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| 426 | .limit = 1,
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| 427 | .pull = &input_pool,
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| 428 | .lock = __SPIN_LOCK_UNLOCKED(&blocking_pool.lock),
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| 429 | .pool = blocking_pool_data
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| 430 | };
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| 431 |
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| 432 | static struct entropy_store nonblocking_pool = {
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| 433 | .poolinfo = &poolinfo_table[1],
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| 434 | .name = "nonblocking",
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| 435 | .pull = &input_pool,
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| 436 | .lock = __SPIN_LOCK_UNLOCKED(&nonblocking_pool.lock),
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| 437 | .pool = nonblocking_pool_data
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| 438 | };
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| 439 |
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| 440 | |
| 441 | * This function adds a byte into the entropy "pool". It does not
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| 442 | * update the entropy estimate. The caller should call
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| 443 | * credit_entropy_store if this is appropriate.
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| 444 | *
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| 445 | * The pool is stirred with a primitive polynomial of the appropriate
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| 446 | * degree, and then twisted. We twist by three bits at a time because
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| 447 | * it's cheap to do so and helps slightly in the expected case where
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| 448 | * the entropy is concentrated in the low-order bits.
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| 449 |
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| 450 | static void __add_entropy_words(struct entropy_store *r, const __u32 *in,
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| 451 | int nwords, __u32 out[16])
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| 452 | {
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| 453 | static __u32 const twist_table[8] = {
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| 454 | 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
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| 455 | 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
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| 456 | unsigned long i, add_ptr, tap1, tap2, tap3, tap4, tap5;
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| 457 | int new_rotate, input_rotate;
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| 458 | int wordmask = r->poolinfo->poolwords - 1;
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| 459 | __u32 w, next_w;
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| 460 | unsigned long flags;
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| 461 |
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| 462 |
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| 463 | tap1 = r->poolinfo->tap1;
|
| 464 | tap2 = r->poolinfo->tap2;
|
| 465 | tap3 = r->poolinfo->tap3;
|
| 466 | tap4 = r->poolinfo->tap4;
|
| 467 | tap5 = r->poolinfo->tap5;
|
| 468 | next_w = *in++;
|
| 469 |
|
| 470 | spin_lock_irqsave(&r->lock, flags);
|
| 471 | prefetch_range(r->pool, wordmask);
|
| 472 | input_rotate = r->input_rotate;
|
| 473 | add_ptr = r->add_ptr;
|
| 474 |
|
| 475 | while (nwords--) {
|
| 476 | w = rol32(next_w, input_rotate);
|
| 477 | if (nwords > 0)
|
| 478 | next_w = *in++;
|
| 479 | i = add_ptr = (add_ptr - 1) & wordmask;
|
| 480 | |
| 481 | * Normally, we add 7 bits of rotation to the pool.
|
| 482 | * At the beginning of the pool, add an extra 7 bits
|
| 483 | * rotation, so that successive passes spread the
|
| 484 | * input bits across the pool evenly.
|
| 485 |
|
| 486 | new_rotate = input_rotate + 14;
|
| 487 | if (i)
|
| 488 | new_rotate = input_rotate + 7;
|
| 489 | input_rotate = new_rotate & 31;
|
| 490 |
|
| 491 |
|
| 492 | w ^= r->pool[(i + tap1) & wordmask];
|
| 493 | w ^= r->pool[(i + tap2) & wordmask];
|
| 494 | w ^= r->pool[(i + tap3) & wordmask];
|
| 495 | w ^= r->pool[(i + tap4) & wordmask];
|
| 496 | w ^= r->pool[(i + tap5) & wordmask];
|
| 497 | w ^= r->pool[i];
|
| 498 | r->pool[i] = (w >> 3) ^ twist_table[w & 7];
|
| 499 | }
|
| 500 |
|
| 501 | r->input_rotate = input_rotate;
|
| 502 | r->add_ptr = add_ptr;
|
| 503 |
|
| 504 | if (out) {
|
| 505 | for (i = 0; i < 16; i++) {
|
| 506 | out[i] = r->pool[add_ptr];
|
| 507 | add_ptr = (add_ptr - 1) & wordmask;
|
| 508 | }
|
| 509 | }
|
| 510 |
|
| 511 | spin_unlock_irqrestore(&r->lock, flags);
|
| 512 | }
|
| 513 |
|
| 514 | static inline void add_entropy_words(struct entropy_store *r, const __u32 *in,
|
| 515 | int nwords)
|
| 516 | {
|
| 517 | __add_entropy_words(r, in, nwords, NULL);
|
| 518 | }
|
| 519 |
|
| 520 | |
| 521 | * Credit (or debit) the entropy store with n bits of entropy
|
| 522 |
|
| 523 | static void credit_entropy_store(struct entropy_store *r, int nbits)
|
| 524 | {
|
| 525 | unsigned long flags;
|
| 526 |
|
| 527 | spin_lock_irqsave(&r->lock, flags);
|
| 528 |
|
| 529 | if (r->entropy_count + nbits < 0) {
|
| 530 | DEBUG_ENT("negative entropy/overflow (%d+%d)\n",
|
| 531 | r->entropy_count, nbits);
|
| 532 | r->entropy_count = 0;
|
| 533 | } else if (r->entropy_count + nbits > r->poolinfo->POOLBITS) {
|
| 534 | r->entropy_count = r->poolinfo->POOLBITS;
|
| 535 | } else {
|
| 536 | r->entropy_count += nbits;
|
| 537 | if (nbits)
|
| 538 | DEBUG_ENT("added %d entropy credits to %s\n",
|
| 539 | nbits, r->name);
|
| 540 | }
|
| 541 |
|
| 542 | spin_unlock_irqrestore(&r->lock, flags);
|
| 543 | }
|
| 544 |
|
| 545 | |
| 546 | *
|
| 547 | * Entropy input management
|
| 548 | *
|
| 549 | ********************************************************************
|
| 550 |
|
| 551 |
|
| 552 | struct timer_rand_state {
|
| 553 | cycles_t last_time;
|
| 554 | long last_delta,last_delta2;
|
| 555 | unsigned dont_count_entropy:1;
|
| 556 | };
|
| 557 |
|
| 558 | static struct timer_rand_state input_timer_state;
|
| 559 | static struct timer_rand_state *irq_timer_state[NR_IRQS];
|
| 560 |
|
| 561 | |
| 562 | * This function adds entropy to the entropy "pool" by using timing
|
| 563 | * delays. It uses the timer_rand_state structure to make an estimate
|
| 564 | * of how many bits of entropy this call has added to the pool.
|
| 565 | *
|
| 566 | * The number "num" is also added to the pool - it should somehow describe
|
| 567 | * the type of event which just happened. This is currently 0-255 for
|
| 568 | * keyboard scan codes, and 256 upwards for interrupts.
|
| 569 | *
|
| 570 |
|
| 571 | static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
|
| 572 | {
|
| 573 | struct {
|
| 574 | cycles_t cycles;
|
| 575 | long jiffies;
|
| 576 | unsigned num;
|
| 577 | } sample;
|
| 578 | long delta, delta2, delta3;
|
| 579 |
|
| 580 | preempt_disable();
|
| 581 |
|
| 582 | if (input_pool.entropy_count > trickle_thresh &&
|
| 583 | (__get_cpu_var(trickle_count)++ & 0xfff))
|
| 584 | goto out;
|
| 585 |
|
| 586 | sample.jiffies = jiffies;
|
| 587 | sample.cycles = get_cycles();
|
| 588 | sample.num = num;
|
| 589 | add_entropy_words(&input_pool, (u32 *)&sample, sizeof(sample)/4);
|
| 590 |
|
| 591 | |
| 592 | * Calculate number of bits of randomness we probably added.
|
| 593 | * We take into account the first, second and third-order deltas
|
| 594 | * in order to make our estimate.
|
| 595 |
|
| 596 |
|
| 597 | if (!state->dont_count_entropy) {
|
| 598 | delta = sample.jiffies - state->last_time;
|
| 599 | state->last_time = sample.jiffies;
|
| 600 |
|
| 601 | delta2 = delta - state->last_delta;
|
| 602 | state->last_delta = delta;
|
| 603 |
|
| 604 | delta3 = delta2 - state->last_delta2;
|
| 605 | state->last_delta2 = delta2;
|
| 606 |
|
| 607 | if (delta < 0)
|
| 608 | delta = -delta;
|
| 609 | if (delta2 < 0)
|
| 610 | delta2 = -delta2;
|
| 611 | if (delta3 < 0)
|
| 612 | delta3 = -delta3;
|
| 613 | if (delta > delta2)
|
| 614 | delta = delta2;
|
| 615 | if (delta > delta3)
|
| 616 | delta = delta3;
|
| 617 |
|
| 618 | |
| 619 | * delta is now minimum absolute delta.
|
| 620 | * Round down by 1 bit on general principles,
|
| 621 | * and limit entropy entimate to 12 bits.
|
| 622 |
|
| 623 | credit_entropy_store(&input_pool,
|
| 624 | min_t(int, fls(delta>>1), 11));
|
| 625 | }
|
| 626 |
|
| 627 | if(input_pool.entropy_count >= random_read_wakeup_thresh)
|
| 628 | wake_up_interruptible(&random_read_wait);
|
| 629 |
|
| 630 | out:
|
| 631 | preempt_enable();
|
| 632 | }
|
| 633 |
|
| 634 | void add_input_randomness(unsigned int type, unsigned int code,
|
| 635 | unsigned int value)
|
| 636 | {
|
| 637 | static unsigned char last_value;
|
| 638 |
|
| 639 |
|
| 640 | if (value == last_value)
|
| 641 | return;
|
| 642 |
|
| 643 | DEBUG_ENT("input event\n");
|
| 644 | last_value = value;
|
| 645 | add_timer_randomness(&input_timer_state,
|
| 646 | (type << 4) ^ code ^ (code >> 4) ^ value);
|
| 647 | }
|
| 648 | EXPORT_SYMBOL_GPL(add_input_randomness);
|
| 649 |
|
| 650 | void add_interrupt_randomness(int irq)
|
| 651 | {
|
| 652 | if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
|
| 653 | return;
|
| 654 |
|
| 655 | DEBUG_ENT("irq event %d\n", irq);
|
| 656 | add_timer_randomness(irq_timer_state[irq], 0x100 + irq);
|
| 657 | }
|
| 658 |
|
| 659 | #ifdef CONFIG_BLOCK
|
| 660 | void add_disk_randomness(struct gendisk *disk)
|
| 661 | {
|
| 662 | if (!disk || !disk->random)
|
| 663 | return;
|
| 664 |
|
| 665 | DEBUG_ENT("disk event %d:%d\n", disk->major, disk->first_minor);
|
| 666 |
|
| 667 | add_timer_randomness(disk->random,
|
| 668 | 0x100 + MKDEV(disk->major, disk->first_minor));
|
| 669 | }
|
| 670 |
|
| 671 | EXPORT_SYMBOL(add_disk_randomness);
|
| 672 | #endif
|
| 673 |
|
| 674 | #define EXTRACT_SIZE 10
|
| 675 |
|
| 676 | |
| 677 | *
|
| 678 | * Entropy extraction routines
|
| 679 | *
|
| 680 | ********************************************************************
|
| 681 |
|
| 682 | static ssize_t extract_entropy(struct entropy_store *r, void * buf,
|
| 683 | size_t nbytes, int min, int rsvd);
|
| 684 |
|
| 685 | |
| 686 | * This utility inline function is responsible for transfering entropy
|
| 687 | * from the primary pool to the secondary extraction pool. We make
|
| 688 | * sure we pull enough for a 'catastrophic reseed'.
|
| 689 |
|
| 690 | static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
|
| 691 | {
|
| 692 | __u32 tmp[OUTPUT_POOL_WORDS];
|
| 693 |
|
| 694 | if (r->pull && r->entropy_count < nbytes * 8 &&
|
| 695 | r->entropy_count < r->poolinfo->POOLBITS) {
|
| 696 | int bytes = max_t(int, random_read_wakeup_thresh / 8,
|
| 697 | min_t(int, nbytes, sizeof(tmp)));
|
| 698 | int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4;
|
| 699 |
|
| 700 | DEBUG_ENT("going to reseed %s with %d bits "
|
| 701 | "(%d of %d requested)\n",
|
| 702 | r->name, bytes * 8, nbytes * 8, r->entropy_count);
|
| 703 |
|
| 704 | bytes=extract_entropy(r->pull, tmp, bytes,
|
| 705 | random_read_wakeup_thresh / 8, rsvd);
|
| 706 | add_entropy_words(r, tmp, (bytes + 3) / 4);
|
| 707 | credit_entropy_store(r, bytes*8);
|
| 708 | }
|
| 709 | }
|
| 710 |
|
| 711 | |
| 712 | * These functions extracts randomness from the "entropy pool", and
|
| 713 | * returns it in a buffer.
|
| 714 | *
|
| 715 | * The min parameter specifies the minimum amount we can pull before
|
| 716 | * failing to avoid races that defeat catastrophic reseeding while the
|
| 717 | * reserved parameter indicates how much entropy we must leave in the
|
| 718 | * pool after each pull to avoid starving other readers.
|
| 719 | *
|
| 720 | * Note: extract_entropy() assumes that .poolwords is a multiple of 16 words.
|
| 721 |
|
| 722 |
|
| 723 | static size_t account(struct entropy_store *r, size_t nbytes, int min,
|
| 724 | int reserved)
|
| 725 | {
|
| 726 | unsigned long flags;
|
| 727 |
|
| 728 | BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);
|
| 729 |
|
| 730 |
|
| 731 | spin_lock_irqsave(&r->lock, flags);
|
| 732 |
|
| 733 | DEBUG_ENT("trying to extract %d bits from %s\n",
|
| 734 | nbytes * 8, r->name);
|
| 735 |
|
| 736 |
|
| 737 | if (r->entropy_count / 8 < min + reserved) {
|
| 738 | nbytes = 0;
|
| 739 | } else {
|
| 740 |
|
| 741 | if (r->limit && nbytes + reserved >= r->entropy_count / 8)
|
| 742 | nbytes = r->entropy_count/8 - reserved;
|
| 743 |
|
| 744 | if(r->entropy_count / 8 >= nbytes + reserved)
|
| 745 | r->entropy_count -= nbytes*8;
|
| 746 | else
|
| 747 | r->entropy_count = reserved;
|
| 748 |
|
| 749 | if (r->entropy_count < random_write_wakeup_thresh)
|
| 750 | wake_up_interruptible(&random_write_wait);
|
| 751 | }
|
| 752 |
|
| 753 | DEBUG_ENT("debiting %d entropy credits from %s%s\n",
|
| 754 | nbytes * 8, r->name, r->limit ? "" : " (unlimited)");
|
| 755 |
|
| 756 | spin_unlock_irqrestore(&r->lock, flags);
|
| 757 |
|
| 758 | return nbytes;
|
| 759 | }
|
| 760 |
|
| 761 | static void extract_buf(struct entropy_store *r, __u8 *out)
|
| 762 | {
|
| 763 | int i, x;
|
| 764 | __u32 data[16], buf[5 + SHA_WORKSPACE_WORDS];
|
| 765 |
|
| 766 | sha_init(buf);
|
| 767 | |
| 768 | * As we hash the pool, we mix intermediate values of
|
| 769 | * the hash back into the pool. This eliminates
|
| 770 | * backtracking attacks (where the attacker knows
|
| 771 | * the state of the pool plus the current outputs, and
|
| 772 | * attempts to find previous ouputs), unless the hash
|
| 773 | * function can be inverted.
|
| 774 |
|
| 775 | for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
|
| 776 | sha_transform(buf, (__u8 *)r->pool+i, buf + 5);
|
| 777 | add_entropy_words(r, &buf[x % 5], 1);
|
| 778 | }
|
| 779 |
|
| 780 | |
| 781 | * To avoid duplicates, we atomically extract a
|
| 782 | * portion of the pool while mixing, and hash one
|
| 783 | * final time.
|
| 784 |
|
| 785 | __add_entropy_words(r, &buf[x % 5], 1, data);
|
| 786 | sha_transform(buf, (__u8 *)data, buf + 5);
|
| 787 |
|
| 788 | |
| 789 | * In case the hash function has some recognizable
|
| 790 | * output pattern, we fold it in half.
|
| 791 |
|
| 792 |
|
| 793 | buf[0] ^= buf[3];
|
| 794 | buf[1] ^= buf[4];
|
| 795 | buf[0] ^= rol32(buf[3], 16);
|
| 796 | memcpy(out, buf, EXTRACT_SIZE);
|
| 797 | memset(buf, 0, sizeof(buf));
|
| 798 | }
|
| 799 |
|
| 800 | static ssize_t extract_entropy(struct entropy_store *r, void * buf,
|
| 801 | size_t nbytes, int min, int reserved)
|
| 802 | {
|
| 803 | ssize_t ret = 0, i;
|
| 804 | __u8 tmp[EXTRACT_SIZE];
|
| 805 |
|
| 806 | xfer_secondary_pool(r, nbytes);
|
| 807 | nbytes = account(r, nbytes, min, reserved);
|
| 808 |
|
| 809 | while (nbytes) {
|
| 810 | extract_buf(r, tmp);
|
| 811 | i = min_t(int, nbytes, EXTRACT_SIZE);
|
| 812 | memcpy(buf, tmp, i);
|
| 813 | nbytes -= i;
|
| 814 | buf += i;
|
| 815 | ret += i;
|
| 816 | }
|
| 817 |
|
| 818 |
|
| 819 | memset(tmp, 0, sizeof(tmp));
|
| 820 |
|
| 821 | return ret;
|
| 822 | }
|
| 823 |
|
| 824 | static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
|
| 825 | size_t nbytes)
|
| 826 | {
|
| 827 | ssize_t ret = 0, i;
|
| 828 | __u8 tmp[EXTRACT_SIZE];
|
| 829 |
|
| 830 | xfer_secondary_pool(r, nbytes);
|
| 831 | nbytes = account(r, nbytes, 0, 0);
|
| 832 |
|
| 833 | while (nbytes) {
|
| 834 | if (need_resched()) {
|
| 835 | if (signal_pending(current)) {
|
| 836 | if (ret == 0)
|
| 837 | ret = -ERESTARTSYS;
|
| 838 | break;
|
| 839 | }
|
| 840 | schedule();
|
| 841 | }
|
| 842 |
|
| 843 | extract_buf(r, tmp);
|
| 844 | i = min_t(int, nbytes, EXTRACT_SIZE);
|
| 845 | if (copy_to_user(buf, tmp, i)) {
|
| 846 | ret = -EFAULT;
|
| 847 | break;
|
| 848 | }
|
| 849 |
|
| 850 | nbytes -= i;
|
| 851 | buf += i;
|
| 852 | ret += i;
|
| 853 | }
|
| 854 |
|
| 855 |
|
| 856 | memset(tmp, 0, sizeof(tmp));
|
| 857 |
|
| 858 | return ret;
|
| 859 | }
|
| 860 |
|
| 861 | |
| 862 | * This function is the exported kernel interface. It returns some
|
| 863 | * number of good random numbers, suitable for seeding TCP sequence
|
| 864 | * numbers, etc.
|
| 865 |
|
| 866 | void get_random_bytes(void *buf, int nbytes)
|
| 867 | {
|
| 868 | extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0);
|
| 869 | }
|
| 870 |
|
| 871 | EXPORT_SYMBOL(get_random_bytes);
|
| 872 |
|
| 873 | |
| 874 | * init_std_data - initialize pool with system data
|
| 875 | *
|
| 876 | * @r: pool to initialize
|
| 877 | *
|
| 878 | * This function clears the pool's entropy count and mixes some system
|
| 879 | * data into the pool to prepare it for use. The pool is not cleared
|
| 880 | * as that can only decrease the entropy in the pool.
|
| 881 |
|
| 882 | static void init_std_data(struct entropy_store *r)
|
| 883 | {
|
| 884 | struct timeval tv;
|
| 885 | unsigned long flags;
|
| 886 |
|
| 887 | spin_lock_irqsave(&r->lock, flags);
|
| 888 | r->entropy_count = 0;
|
| 889 | spin_unlock_irqrestore(&r->lock, flags);
|
| 890 |
|
| 891 | do_gettimeofday(&tv);
|
| 892 | add_entropy_words(r, (__u32 *)&tv, sizeof(tv)/4);
|
| 893 | add_entropy_words(r, (__u32 *)utsname(),
|
| 894 | sizeof(*(utsname()))/4);
|
| 895 | }
|
| 896 |
|
| 897 | static int __init rand_initialize(void)
|
| 898 | {
|
| 899 | init_std_data(&input_pool);
|
| 900 | init_std_data(&blocking_pool);
|
| 901 | init_std_data(&nonblocking_pool);
|
| 902 | return 0;
|
| 903 | }
|
| 904 | module_init(rand_initialize);
|
| 905 |
|
| 906 | void rand_initialize_irq(int irq)
|
| 907 | {
|
| 908 | struct timer_rand_state *state;
|
| 909 |
|
| 910 | if (irq >= NR_IRQS || irq_timer_state[irq])
|
| 911 | return;
|
| 912 |
|
| 913 | |
| 914 | * If kmalloc returns null, we just won't use that entropy
|
| 915 | * source.
|
| 916 |
|
| 917 | state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
|
| 918 | if (state) {
|
| 919 | memset(state, 0, sizeof(struct timer_rand_state));
|
| 920 | irq_timer_state[irq] = state;
|
| 921 | }
|
| 922 | }
|
| 923 |
|
| 924 | #ifdef CONFIG_BLOCK
|
| 925 | void rand_initialize_disk(struct gendisk *disk)
|
| 926 | {
|
| 927 | struct timer_rand_state *state;
|
| 928 |
|
| 929 | |
| 930 | * If kmalloc returns null, we just won't use that entropy
|
| 931 | * source.
|
| 932 |
|
| 933 | state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
|
| 934 | if (state) {
|
| 935 | memset(state, 0, sizeof(struct timer_rand_state));
|
| 936 | disk->random = state;
|
| 937 | }
|
| 938 | }
|
| 939 | #endif
|
| 940 |
|
| 941 | static ssize_t
|
| 942 | random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
|
| 943 | {
|
| 944 | ssize_t n, retval = 0, count = 0;
|
| 945 |
|
| 946 | if (nbytes == 0)
|
| 947 | return 0;
|
| 948 |
|
| 949 | while (nbytes > 0) {
|
| 950 | n = nbytes;
|
| 951 | if (n > SEC_XFER_SIZE)
|
| 952 | n = SEC_XFER_SIZE;
|
| 953 |
|
| 954 | DEBUG_ENT("reading %d bits\n", n*8);
|
| 955 |
|
| 956 | n = extract_entropy_user(&blocking_pool, buf, n);
|
| 957 |
|
| 958 | DEBUG_ENT("read got %d bits (%d still needed)\n",
|
| 959 | n*8, (nbytes-n)*8);
|
| 960 |
|
| 961 | if (n == 0) {
|
| 962 | if (file->f_flags & O_NONBLOCK) {
|
| 963 | retval = -EAGAIN;
|
| 964 | break;
|
| 965 | }
|
| 966 |
|
| 967 | DEBUG_ENT("sleeping?\n");
|
| 968 |
|
| 969 | wait_event_interruptible(random_read_wait,
|
| 970 | input_pool.entropy_count >=
|
| 971 | random_read_wakeup_thresh);
|
| 972 |
|
| 973 | DEBUG_ENT("awake\n");
|
| 974 |
|
| 975 | if (signal_pending(current)) {
|
| 976 | retval = -ERESTARTSYS;
|
| 977 | break;
|
| 978 | }
|
| 979 |
|
| 980 | continue;
|
| 981 | }
|
| 982 |
|
| 983 | if (n < 0) {
|
| 984 | retval = n;
|
| 985 | break;
|
| 986 | }
|
| 987 | count += n;
|
| 988 | buf += n;
|
| 989 | nbytes -= n;
|
| 990 | break;
|
| 991 |
|
| 992 | }
|
| 993 |
|
| 994 | |
| 995 | * If we gave the user some bytes, update the access time.
|
| 996 |
|
| 997 | if (count)
|
| 998 | file_accessed(file);
|
| 999 |
|
| 1000 | return (count ? count : retval);
|
| 1001 | }
|
| 1002 |
|
| 1003 | static ssize_t
|
| 1004 | urandom_read(struct file * file, char __user * buf,
|
| 1005 | size_t nbytes, loff_t *ppos)
|
| 1006 | {
|
| 1007 | return extract_entropy_user(&nonblocking_pool, buf, nbytes);
|
| 1008 | }
|
| 1009 |
|
| 1010 | static unsigned int
|
| 1011 | random_poll(struct file *file, poll_table * wait)
|
| 1012 | {
|
| 1013 | unsigned int mask;
|
| 1014 |
|
| 1015 | poll_wait(file, &random_read_wait, wait);
|
| 1016 | poll_wait(file, &random_write_wait, wait);
|
| 1017 | mask = 0;
|
| 1018 | if (input_pool.entropy_count >= random_read_wakeup_thresh)
|
| 1019 | mask |= POLLIN | POLLRDNORM;
|
| 1020 | if (input_pool.entropy_count < random_write_wakeup_thresh)
|
| 1021 | mask |= POLLOUT | POLLWRNORM;
|
| 1022 | return mask;
|
| 1023 | }
|
| 1024 |
|
| 1025 | static ssize_t
|
| 1026 | random_write(struct file * file, const char __user * buffer,
|
| 1027 | size_t count, loff_t *ppos)
|
| 1028 | {
|
| 1029 | int ret = 0;
|
| 1030 | size_t bytes;
|
| 1031 | __u32 buf[16];
|
| 1032 | const char __user *p = buffer;
|
| 1033 | size_t c = count;
|
| 1034 |
|
| 1035 | while (c > 0) {
|
| 1036 | bytes = min(c, sizeof(buf));
|
| 1037 |
|
| 1038 | bytes -= copy_from_user(&buf, p, bytes);
|
| 1039 | if (!bytes) {
|
| 1040 | ret = -EFAULT;
|
| 1041 | break;
|
| 1042 | }
|
| 1043 | c -= bytes;
|
| 1044 | p += bytes;
|
| 1045 |
|
| 1046 | add_entropy_words(&input_pool, buf, (bytes + 3) / 4);
|
| 1047 | }
|
| 1048 | if (p == buffer) {
|
| 1049 | return (ssize_t)ret;
|
| 1050 | } else {
|
| 1051 | struct inode *inode = file->f_path.dentry->d_inode;
|
| 1052 | inode->i_mtime = current_fs_time(inode->i_sb);
|
| 1053 | mark_inode_dirty(inode);
|
| 1054 | return (ssize_t)(p - buffer);
|
| 1055 | }
|
| 1056 | }
|
| 1057 |
|
| 1058 | static int
|
| 1059 | random_ioctl(struct inode * inode, struct file * file,
|
| 1060 | unsigned int cmd, unsigned long arg)
|
| 1061 | {
|
| 1062 | int size, ent_count;
|
| 1063 | int __user *p = (int __user *)arg;
|
| 1064 | int retval;
|
| 1065 |
|
| 1066 | switch (cmd) {
|
| 1067 | case RNDGETENTCNT:
|
| 1068 | ent_count = input_pool.entropy_count;
|
| 1069 | if (put_user(ent_count, p))
|
| 1070 | return -EFAULT;
|
| 1071 | return 0;
|
| 1072 | case RNDADDTOENTCNT:
|
| 1073 | if (!capable(CAP_SYS_ADMIN))
|
| 1074 | return -EPERM;
|
| 1075 | if (get_user(ent_count, p))
|
| 1076 | return -EFAULT;
|
| 1077 | credit_entropy_store(&input_pool, ent_count);
|
| 1078 | |
| 1079 | * Wake up waiting processes if we have enough
|
| 1080 | * entropy.
|
| 1081 |
|
| 1082 | if (input_pool.entropy_count >= random_read_wakeup_thresh)
|
| 1083 | wake_up_interruptible(&random_read_wait);
|
| 1084 | return 0;
|
| 1085 | case RNDADDENTROPY:
|
| 1086 | if (!capable(CAP_SYS_ADMIN))
|
| 1087 | return -EPERM;
|
| 1088 | if (get_user(ent_count, p++))
|
| 1089 | return -EFAULT;
|
| 1090 | if (ent_count < 0)
|
| 1091 | return -EINVAL;
|
| 1092 | if (get_user(size, p++))
|
| 1093 | return -EFAULT;
|
| 1094 | retval = random_write(file, (const char __user *) p,
|
| 1095 | size, &file->f_pos);
|
| 1096 | if (retval < 0)
|
| 1097 | return retval;
|
| 1098 | credit_entropy_store(&input_pool, ent_count);
|
| 1099 | |
| 1100 | * Wake up waiting processes if we have enough
|
| 1101 | * entropy.
|
| 1102 |
|
| 1103 | if (input_pool.entropy_count >= random_read_wakeup_thresh)
|
| 1104 | wake_up_interruptible(&random_read_wait);
|
| 1105 | return 0;
|
| 1106 | case RNDZAPENTCNT:
|
| 1107 | case RNDCLEARPOOL:
|
| 1108 |
|
| 1109 | if (!capable(CAP_SYS_ADMIN))
|
| 1110 | return -EPERM;
|
| 1111 | init_std_data(&input_pool);
|
| 1112 | init_std_data(&blocking_pool);
|
| 1113 | init_std_data(&nonblocking_pool);
|
| 1114 | return 0;
|
| 1115 | default:
|
| 1116 | return -EINVAL;
|
| 1117 | }
|
| 1118 | }
|
| 1119 |
|
| 1120 | const struct file_operations random_fops = {
|
| 1121 | .read = random_read,
|
| 1122 | .write = random_write,
|
| 1123 | .poll = random_poll,
|
| 1124 | .ioctl = random_ioctl,
|
| 1125 | };
|
| 1126 |
|
| 1127 | const struct file_operations urandom_fops = {
|
| 1128 | .read = urandom_read,
|
| 1129 | .write = random_write,
|
| 1130 | .ioctl = random_ioctl,
|
| 1131 | };
|
| 1132 |
|
| 1133 | |
| 1134 | * Random UUID interface
|
| 1135 | *
|
| 1136 | * Used here for a Boot ID, but can be useful for other kernel
|
| 1137 | * drivers.
|
| 1138 | **************************************************************
|
| 1139 |
|
| 1140 | |
| 1141 | * Generate random UUID
|
| 1142 |
|
| 1143 | void generate_random_uuid(unsigned char uuid_out[16])
|
| 1144 | {
|
| 1145 | get_random_bytes(uuid_out, 16);
|
| 1146 |
|
| 1147 | uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40;
|
| 1148 |
|
| 1149 | uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
|
| 1150 | }
|
| 1151 |
|
| 1152 | EXPORT_SYMBOL(generate_random_uuid);
|
| 1153 |
|
| 1154 | |
| 1155 | *
|
| 1156 | * Sysctl interface
|
| 1157 | *
|
| 1158 | *******************************************************************
|
| 1159 |
|
| 1160 | #ifdef CONFIG_SYSCTL
|
| 1161 |
|
| 1162 | #include <linux/sysctl.h>
|
| 1163 |
|
| 1164 | static int min_read_thresh = 8, min_write_thresh;
|
| 1165 | static int max_read_thresh = INPUT_POOL_WORDS * 32;
|
| 1166 | static int max_write_thresh = INPUT_POOL_WORDS * 32;
|
| 1167 | static char sysctl_bootid[16];
|
| 1168 |
|
| 1169 | |
| 1170 | * These functions is used to return both the bootid UUID, and random
|
| 1171 | * UUID. The difference is in whether table->data is NULL; if it is,
|
| 1172 | * then a new UUID is generated and returned to the user.
|
| 1173 | *
|
| 1174 | * If the user accesses this via the proc interface, it will be returned
|
| 1175 | * as an ASCII string in the standard UUID format. If accesses via the
|
| 1176 | * sysctl system call, it is returned as 16 bytes of binary data.
|
| 1177 |
|
| 1178 | static int proc_do_uuid(ctl_table *table, int write, struct file *filp,
|
| 1179 | void __user *buffer, size_t *lenp, loff_t *ppos)
|
| 1180 | {
|
| 1181 | ctl_table fake_table;
|
| 1182 | unsigned char buf[64], tmp_uuid[16], *uuid;
|
| 1183 |
|
| 1184 | uuid = table->data;
|
| 1185 | if (!uuid) {
|
| 1186 | uuid = tmp_uuid;
|
| 1187 | uuid[8] = 0;
|
| 1188 | }
|
| 1189 | if (uuid[8] == 0)
|
| 1190 | generate_random_uuid(uuid);
|
| 1191 |
|
| 1192 | sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-"
|
| 1193 | "%02x%02x%02x%02x%02x%02x",
|
| 1194 | uuid[0], uuid[1], uuid[2], uuid[3],
|
| 1195 | uuid[4], uuid[5], uuid[6], uuid[7],
|
| 1196 | uuid[8], uuid[9], uuid[10], uuid[11],
|
| 1197 | uuid[12], uuid[13], uuid[14], uuid[15]);
|
| 1198 | fake_table.data = buf;
|
| 1199 | fake_table.maxlen = sizeof(buf);
|
| 1200 |
|
| 1201 | return proc_dostring(&fake_table, write, filp, buffer, lenp, ppos);
|
| 1202 | }
|
| 1203 |
|
| 1204 | static int uuid_strategy(ctl_table *table, int __user *name, int nlen,
|
| 1205 | void __user *oldval, size_t __user *oldlenp,
|
| 1206 | void __user *newval, size_t newlen)
|
| 1207 | {
|
| 1208 | unsigned char tmp_uuid[16], *uuid;
|
| 1209 | unsigned int len;
|
| 1210 |
|
| 1211 | if (!oldval || !oldlenp)
|
| 1212 | return 1;
|
| 1213 |
|
| 1214 | uuid = table->data;
|
| 1215 | if (!uuid) {
|
| 1216 | uuid = tmp_uuid;
|
| 1217 | uuid[8] = 0;
|
| 1218 | }
|
| 1219 | if (uuid[8] == 0)
|
| 1220 | generate_random_uuid(uuid);
|
| 1221 |
|
| 1222 | if (get_user(len, oldlenp))
|
| 1223 | return -EFAULT;
|
| 1224 | if (len) {
|
| 1225 | if (len > 16)
|
| 1226 | len = 16;
|
| 1227 | if (copy_to_user(oldval, uuid, len) ||
|
| 1228 | put_user(len, oldlenp))
|
| 1229 | return -EFAULT;
|
| 1230 | }
|
| 1231 | return 1;
|
| 1232 | }
|
| 1233 |
|
| 1234 | static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
|
| 1235 | ctl_table random_table[] = {
|
| 1236 | {
|
| 1237 | .ctl_name = RANDOM_POOLSIZE,
|
| 1238 | .procname = "poolsize",
|
| 1239 | .data = &sysctl_poolsize,
|
| 1240 | .maxlen = sizeof(int),
|
| 1241 | .mode = 0444,
|
| 1242 | .proc_handler = &proc_dointvec,
|
| 1243 | },
|
| 1244 | {
|
| 1245 | .ctl_name = RANDOM_ENTROPY_COUNT,
|
| 1246 | .procname = "entropy_avail",
|
| 1247 | .maxlen = sizeof(int),
|
| 1248 | .mode = 0444,
|
| 1249 | .proc_handler = &proc_dointvec,
|
| 1250 | .data = &input_pool.entropy_count,
|
| 1251 | },
|
| 1252 | {
|
| 1253 | .ctl_name = RANDOM_READ_THRESH,
|
| 1254 | .procname = "read_wakeup_threshold",
|
| 1255 | .data = &random_read_wakeup_thresh,
|
| 1256 | .maxlen = sizeof(int),
|
| 1257 | .mode = 0644,
|
| 1258 | .proc_handler = &proc_dointvec_minmax,
|
| 1259 | .strategy = &sysctl_intvec,
|
| 1260 | .extra1 = &min_read_thresh,
|
| 1261 | .extra2 = &max_read_thresh,
|
| 1262 | },
|
| 1263 | {
|
| 1264 | .ctl_name = RANDOM_WRITE_THRESH,
|
| 1265 | .procname = "write_wakeup_threshold",
|
| 1266 | .data = &random_write_wakeup_thresh,
|
| 1267 | .maxlen = sizeof(int),
|
| 1268 | .mode = 0644,
|
| 1269 | .proc_handler = &proc_dointvec_minmax,
|
| 1270 | .strategy = &sysctl_intvec,
|
| 1271 | .extra1 = &min_write_thresh,
|
| 1272 | .extra2 = &max_write_thresh,
|
| 1273 | },
|
| 1274 | {
|
| 1275 | .ctl_name = RANDOM_BOOT_ID,
|
| 1276 | .procname = "boot_id",
|
| 1277 | .data = &sysctl_bootid,
|
| 1278 | .maxlen = 16,
|
| 1279 | .mode = 0444,
|
| 1280 | .proc_handler = &proc_do_uuid,
|
| 1281 | .strategy = &uuid_strategy,
|
| 1282 | },
|
| 1283 | {
|
| 1284 | .ctl_name = RANDOM_UUID,
|
| 1285 | .procname = "uuid",
|
| 1286 | .maxlen = 16,
|
| 1287 | .mode = 0444,
|
| 1288 | .proc_handler = &proc_do_uuid,
|
| 1289 | .strategy = &uuid_strategy,
|
| 1290 | },
|
| 1291 | { .ctl_name = 0 }
|
| 1292 | };
|
| 1293 | #endif
|
| 1294 |
|
| 1295 | |
| 1296 | *
|
| 1297 | * Random funtions for networking
|
| 1298 | *
|
| 1299 | *******************************************************************
|
| 1300 |
|
| 1301 | |
| 1302 | * TCP initial sequence number picking. This uses the random number
|
| 1303 | * generator to pick an initial secret value. This value is hashed
|
| 1304 | * along with the TCP endpoint information to provide a unique
|
| 1305 | * starting point for each pair of TCP endpoints. This defeats
|
| 1306 | * attacks which rely on guessing the initial TCP sequence number.
|
| 1307 | * This algorithm was suggested by Steve Bellovin.
|
| 1308 | *
|
| 1309 | * Using a very strong hash was taking an appreciable amount of the total
|
| 1310 | * TCP connection establishment time, so this is a weaker hash,
|
| 1311 | * compensated for by changing the secret periodically.
|
| 1312 |
|
| 1313 |
|
| 1314 |
|
| 1315 | #define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
|
| 1316 | #define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
|
| 1317 | #define H(x, y, z) ((x) ^ (y) ^ (z))
|
| 1318 |
|
| 1319 | |
| 1320 | * The generic round function. The application is so specific that
|
| 1321 | * we don't bother protecting all the arguments with parens, as is generally
|
| 1322 | * good macro practice, in favor of extra legibility.
|
| 1323 | * Rotation is separate from addition to prevent recomputation
|
| 1324 |
|
| 1325 | #define ROUND(f, a, b, c, d, x, s) \
|
| 1326 | (a += f(b, c, d) + x, a = (a << s) | (a >> (32 - s)))
|
| 1327 | #define K1 0
|
| 1328 | #define K2 013240474631UL
|
| 1329 | #define K3 015666365641UL
|
| 1330 |
|
| 1331 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
|
| 1332 |
|
| 1333 | static __u32 twothirdsMD4Transform (__u32 const buf[4], __u32 const in[12])
|
| 1334 | {
|
| 1335 | __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
|
| 1336 |
|
| 1337 |
|
| 1338 | ROUND(F, a, b, c, d, in[ 0] + K1, 3);
|
| 1339 | ROUND(F, d, a, b, c, in[ 1] + K1, 7);
|
| 1340 | ROUND(F, c, d, a, b, in[ 2] + K1, 11);
|
| 1341 | ROUND(F, b, c, d, a, in[ 3] + K1, 19);
|
| 1342 | ROUND(F, a, b, c, d, in[ 4] + K1, 3);
|
| 1343 | ROUND(F, d, a, b, c, in[ 5] + K1, 7);
|
| 1344 | ROUND(F, c, d, a, b, in[ 6] + K1, 11);
|
| 1345 | ROUND(F, b, c, d, a, in[ 7] + K1, 19);
|
| 1346 | ROUND(F, a, b, c, d, in[ 8] + K1, 3);
|
| 1347 | ROUND(F, d, a, b, c, in[ 9] + K1, 7);
|
| 1348 | ROUND(F, c, d, a, b, in[10] + K1, 11);
|
| 1349 | ROUND(F, b, c, d, a, in[11] + K1, 19);
|
| 1350 |
|
| 1351 |
|
| 1352 | ROUND(G, a, b, c, d, in[ 1] + K2, 3);
|
| 1353 | ROUND(G, d, a, b, c, in[ 3] + K2, 5);
|
| 1354 | ROUND(G, c, d, a, b, in[ 5] + K2, 9);
|
| 1355 | ROUND(G, b, c, d, a, in[ 7] + K2, 13);
|
| 1356 | ROUND(G, a, b, c, d, in[ 9] + K2, 3);
|
| 1357 | ROUND(G, d, a, b, c, in[11] + K2, 5);
|
| 1358 | ROUND(G, c, d, a, b, in[ 0] + K2, 9);
|
| 1359 | ROUND(G, b, c, d, a, in[ 2] + K2, 13);
|
| 1360 | ROUND(G, a, b, c, d, in[ 4] + K2, 3);
|
| 1361 | ROUND(G, d, a, b, c, in[ 6] + K2, 5);
|
| 1362 | ROUND(G, c, d, a, b, in[ 8] + K2, 9);
|
| 1363 | ROUND(G, b, c, d, a, in[10] + K2, 13);
|
| 1364 |
|
| 1365 |
|
| 1366 | ROUND(H, a, b, c, d, in[ 3] + K3, 3);
|
| 1367 | ROUND(H, d, a, b, c, in[ 7] + K3, 9);
|
| 1368 | ROUND(H, c, d, a, b, in[11] + K3, 11);
|
| 1369 | ROUND(H, b, c, d, a, in[ 2] + K3, 15);
|
| 1370 | ROUND(H, a, b, c, d, in[ 6] + K3, 3);
|
| 1371 | ROUND(H, d, a, b, c, in[10] + K3, 9);
|
| 1372 | ROUND(H, c, d, a, b, in[ 1] + K3, 11);
|
| 1373 | ROUND(H, b, c, d, a, in[ 5] + K3, 15);
|
| 1374 | ROUND(H, a, b, c, d, in[ 9] + K3, 3);
|
| 1375 | ROUND(H, d, a, b, c, in[ 0] + K3, 9);
|
| 1376 | ROUND(H, c, d, a, b, in[ 4] + K3, 11);
|
| 1377 | ROUND(H, b, c, d, a, in[ 8] + K3, 15);
|
| 1378 |
|
| 1379 | return buf[1] + b;
|
| 1380 |
|
| 1381 | }
|
| 1382 | #endif
|
| 1383 |
|
| 1384 | #undef ROUND
|
| 1385 | #undef F
|
| 1386 | #undef G
|
| 1387 | #undef H
|
| 1388 | #undef K1
|
| 1389 | #undef K2
|
| 1390 | #undef K3
|
| 1391 |
|
| 1392 |
|
| 1393 | #define REKEY_INTERVAL (300 * HZ)
|
| 1394 | |
| 1395 | * Bit layout of the tcp sequence numbers (before adding current time):
|
| 1396 | * bit 24-31: increased after every key exchange
|
| 1397 | * bit 0-23: hash(source,dest)
|
| 1398 | *
|
| 1399 | * The implementation is similar to the algorithm described
|
| 1400 | * in the Appendix of RFC 1185, except that
|
| 1401 | * - it uses a 1 MHz clock instead of a 250 kHz clock
|
| 1402 | * - it performs a rekey every 5 minutes, which is equivalent
|
| 1403 | * to a (source,dest) tulple dependent forward jump of the
|
| 1404 | * clock by 0..2^(HASH_BITS+1)
|
| 1405 | *
|
| 1406 | * Thus the average ISN wraparound time is 68 minutes instead of
|
| 1407 | * 4.55 hours.
|
| 1408 | *
|
| 1409 | * SMP cleanup and lock avoidance with poor man's RCU.
|
| 1410 | * Manfred Spraul <[email protected]>
|
| 1411 | *
|
| 1412 |
|
| 1413 | #define COUNT_BITS 8
|
| 1414 | #define COUNT_MASK ((1 << COUNT_BITS) - 1)
|
| 1415 | #define HASH_BITS 24
|
| 1416 | #define HASH_MASK ((1 << HASH_BITS) - 1)
|
| 1417 |
|
| 1418 | static struct keydata {
|
| 1419 | __u32 count;
|
| 1420 | __u32 secret[12];
|
| 1421 | } ____cacheline_aligned ip_keydata[2];
|
| 1422 |
|
| 1423 | static unsigned int ip_cnt;
|
| 1424 |
|
| 1425 | static void rekey_seq_generator(struct work_struct *work);
|
| 1426 |
|
| 1427 | static DECLARE_DELAYED_WORK(rekey_work, rekey_seq_generator);
|
| 1428 |
|
| 1429 | |
| 1430 | * Lock avoidance:
|
| 1431 | * The ISN generation runs lockless - it's just a hash over random data.
|
| 1432 | * State changes happen every 5 minutes when the random key is replaced.
|
| 1433 | * Synchronization is performed by having two copies of the hash function
|
| 1434 | * state and rekey_seq_generator always updates the inactive copy.
|
| 1435 | * The copy is then activated by updating ip_cnt.
|
| 1436 | * The implementation breaks down if someone blocks the thread
|
| 1437 | * that processes SYN requests for more than 5 minutes. Should never
|
| 1438 | * happen, and even if that happens only a not perfectly compliant
|
| 1439 | * ISN is generated, nothing fatal.
|
| 1440 |
|
| 1441 | static void rekey_seq_generator(struct work_struct *work)
|
| 1442 | {
|
| 1443 | struct keydata *keyptr = &ip_keydata[1 ^ (ip_cnt & 1)];
|
| 1444 |
|
| 1445 | get_random_bytes(keyptr->secret, sizeof(keyptr->secret));
|
| 1446 | keyptr->count = (ip_cnt & COUNT_MASK) << HASH_BITS;
|
| 1447 | smp_wmb();
|
| 1448 | ip_cnt++;
|
| 1449 | schedule_delayed_work(&rekey_work, REKEY_INTERVAL);
|
| 1450 | }
|
| 1451 |
|
| 1452 | static inline struct keydata *get_keyptr(void)
|
| 1453 | {
|
| 1454 | struct keydata *keyptr = &ip_keydata[ip_cnt & 1];
|
| 1455 |
|
| 1456 | smp_rmb();
|
| 1457 |
|
| 1458 | return keyptr;
|
| 1459 | }
|
| 1460 |
|
| 1461 | static __init int seqgen_init(void)
|
| 1462 | {
|
| 1463 | rekey_seq_generator(NULL);
|
| 1464 | return 0;
|
| 1465 | }
|
| 1466 | late_initcall(seqgen_init);
|
| 1467 |
|
| 1468 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
|
| 1469 | __u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
|
| 1470 | __be16 sport, __be16 dport)
|
| 1471 | {
|
| 1472 | struct timeval tv;
|
| 1473 | __u32 seq;
|
| 1474 | __u32 hash[12];
|
| 1475 | struct keydata *keyptr = get_keyptr();
|
| 1476 |
|
| 1477 | |
| 1478 | * Thus we must use twothirdsMD4Transform.
|
| 1479 |
|
| 1480 |
|
| 1481 | memcpy(hash, saddr, 16);
|
| 1482 | hash[4]=((__force u16)sport << 16) + (__force u16)dport;
|
| 1483 | memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7);
|
| 1484 |
|
| 1485 | seq = twothirdsMD4Transform((const __u32 *)daddr, hash) & HASH_MASK;
|
| 1486 | seq += keyptr->count;
|
| 1487 |
|
| 1488 | do_gettimeofday(&tv);
|
| 1489 | seq += tv.tv_usec + tv.tv_sec * 1000000;
|
| 1490 |
|
| 1491 | return seq;
|
| 1492 | }
|
| 1493 | EXPORT_SYMBOL(secure_tcpv6_sequence_number);
|
| 1494 | #endif
|
| 1495 |
|
| 1496 | |
| 1497 | * All blames to Andrey V. Savochkin <[email protected]>.
|
| 1498 |
|
| 1499 | __u32 secure_ip_id(__be32 daddr)
|
| 1500 | {
|
| 1501 | struct keydata *keyptr;
|
| 1502 | __u32 hash[4];
|
| 1503 |
|
| 1504 | keyptr = get_keyptr();
|
| 1505 |
|
| 1506 | |
| 1507 | * Pick a unique starting offset for each IP destination.
|
| 1508 | * The dest ip address is placed in the starting vector,
|
| 1509 | * which is then hashed with random data.
|
| 1510 |
|
| 1511 | hash[0] = (__force __u32)daddr;
|
| 1512 | hash[1] = keyptr->secret[9];
|
| 1513 | hash[2] = keyptr->secret[10];
|
| 1514 | hash[3] = keyptr->secret[11];
|
| 1515 |
|
| 1516 | return half_md4_transform(hash, keyptr->secret);
|
| 1517 | }
|
| 1518 |
|
| 1519 | #ifdef CONFIG_INET
|
| 1520 |
|
| 1521 | __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
|
| 1522 | __be16 sport, __be16 dport)
|
| 1523 | {
|
| 1524 | struct timeval tv;
|
| 1525 | __u32 seq;
|
| 1526 | __u32 hash[4];
|
| 1527 | struct keydata *keyptr = get_keyptr();
|
| 1528 |
|
| 1529 | |
| 1530 | * Pick a unique starting offset for each TCP connection endpoints
|
| 1531 | * (saddr, daddr, sport, dport).
|
| 1532 | * Note that the words are placed into the starting vector, which is
|
| 1533 | * then mixed with a partial MD4 over random data.
|
| 1534 |
|
| 1535 | hash[0]=(__force u32)saddr;
|
| 1536 | hash[1]=(__force u32)daddr;
|
| 1537 | hash[2]=((__force u16)sport << 16) + (__force u16)dport;
|
| 1538 | hash[3]=keyptr->secret[11];
|
| 1539 |
|
| 1540 | seq = half_md4_transform(hash, keyptr->secret) & HASH_MASK;
|
| 1541 | seq += keyptr->count;
|
| 1542 | |
| 1543 | * As close as possible to RFC 793, which
|
| 1544 | * suggests using a 250 kHz clock.
|
| 1545 | * Further reading shows this assumes 2 Mb/s networks.
|
| 1546 | * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
|
| 1547 | * That's funny, Linux has one built in! Use it!
|
| 1548 | * (Networks are faster now - should this be increased?)
|
| 1549 |
|
| 1550 | do_gettimeofday(&tv);
|
| 1551 | seq += tv.tv_usec + tv.tv_sec * 1000000;
|
| 1552 | #if 0 |
| 1553 | printk("init_seq(%lx, %lx, %d, %d) = %d\n",
|
| 1554 | saddr, daddr, sport, dport, seq);
|
| 1555 | #endif
|
| 1556 | return seq;
|
| 1557 | }
|
| 1558 |
|
| 1559 | EXPORT_SYMBOL(secure_tcp_sequence_number);
|
| 1560 |
|
| 1561 |
|
| 1562 | u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
|
| 1563 | {
|
| 1564 | struct keydata *keyptr = get_keyptr();
|
| 1565 | u32 hash[4];
|
| 1566 |
|
| 1567 | |
| 1568 | * Pick a unique starting offset for each ephemeral port search
|
| 1569 | * (saddr, daddr, dport) and 48bits of random data.
|
| 1570 |
|
| 1571 | hash[0] = (__force u32)saddr;
|
| 1572 | hash[1] = (__force u32)daddr;
|
| 1573 | hash[2] = (__force u32)dport ^ keyptr->secret[10];
|
| 1574 | hash[3] = keyptr->secret[11];
|
| 1575 |
|
| 1576 | return half_md4_transform(hash, keyptr->secret);
|
| 1577 | }
|
| 1578 |
|
| 1579 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
|
| 1580 | u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, __be16 dport)
|
| 1581 | {
|
| 1582 | struct keydata *keyptr = get_keyptr();
|
| 1583 | u32 hash[12];
|
| 1584 |
|
| 1585 | memcpy(hash, saddr, 16);
|
| 1586 | hash[4] = (__force u32)dport;
|
| 1587 | memcpy(&hash[5],keyptr->secret,sizeof(__u32) * 7);
|
| 1588 |
|
| 1589 | return twothirdsMD4Transform((const __u32 *)daddr, hash);
|
| 1590 | }
|
| 1591 | #endif
|
| 1592 |
|
| 1593 | #if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
|
| 1594 | |
| 1595 | * bit's 32-47 increase every key exchange
|
| 1596 | * 0-31 hash(source, dest)
|
| 1597 |
|
| 1598 | u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
|
| 1599 | __be16 sport, __be16 dport)
|
| 1600 | {
|
| 1601 | struct timeval tv;
|
| 1602 | u64 seq;
|
| 1603 | __u32 hash[4];
|
| 1604 | struct keydata *keyptr = get_keyptr();
|
| 1605 |
|
| 1606 | hash[0] = (__force u32)saddr;
|
| 1607 | hash[1] = (__force u32)daddr;
|
| 1608 | hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
|
| 1609 | hash[3] = keyptr->secret[11];
|
| 1610 |
|
| 1611 | seq = half_md4_transform(hash, keyptr->secret);
|
| 1612 | seq |= ((u64)keyptr->count) << (32 - HASH_BITS);
|
| 1613 |
|
| 1614 | do_gettimeofday(&tv);
|
| 1615 | seq += tv.tv_usec + tv.tv_sec * 1000000;
|
| 1616 | seq &= (1ull << 48) - 1;
|
| 1617 | #if 0 |
| 1618 | printk("dccp init_seq(%lx, %lx, %d, %d) = %d\n",
|
| 1619 | saddr, daddr, sport, dport, seq);
|
| 1620 | #endif
|
| 1621 | return seq;
|
| 1622 | }
|
| 1623 |
|
| 1624 | EXPORT_SYMBOL(secure_dccp_sequence_number);
|
| 1625 | #endif
|
| 1626 |
|
| 1627 | #endif
|
| 1628 |
|
| 1629 |
|
| 1630 | |
| 1631 | * Get a random word for internal kernel use only. Similar to urandom but
|
| 1632 | * with the goal of minimal entropy pool depletion. As a result, the random
|
| 1633 | * value is not cryptographically secure but for several uses the cost of
|
| 1634 | * depleting entropy is too high
|
| 1635 |
|
| 1636 | unsigned int get_random_int(void)
|
| 1637 | {
|
| 1638 | |
| 1639 | * Use IP's RNG. It suits our purpose perfectly: it re-keys itself
|
| 1640 | * every second, from the entropy pool (and thus creates a limited
|
| 1641 | * drain on it), and uses halfMD4Transform within the second. We
|
| 1642 | * also mix it with jiffies and the PID:
|
| 1643 |
|
| 1644 | return secure_ip_id((__force __be32)(current->pid + jiffies));
|
| 1645 | }
|
| 1646 |
|
| 1647 | |
| 1648 | * randomize_range() returns a start address such that
|
| 1649 | *
|
| 1650 | * [...... <range> .....]
|
| 1651 | * start end
|
| 1652 | *
|
| 1653 | * a <range> with size "len" starting at the return value is inside in the
|
| 1654 | * area defined by [start, end], but is otherwise randomized.
|
| 1655 |
|
| 1656 | unsigned long
|
| 1657 | randomize_range(unsigned long start, unsigned long end, unsigned long len)
|
| 1658 | {
|
| 1659 | unsigned long range = end - len - start;
|
| 1660 |
|
| 1661 | if (end <= start + len)
|
| 1662 | return 0;
|
| 1663 | return PAGE_ALIGN(get_random_int() % range + start);
|
| 1664 | }
|