123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140114111421143114411451146114711481149115011511152115311541155115611571158115911601161116211631164116511661167116811691170117111721173117411751176117711781179118011811182118311841185118611871188118911901191119211931194119511961197119811991200120112021203120412051206120712081209121012111212121312141215121612171218121912201221122212231224122512261227122812291230123112321233123412351236123712381239124012411242124312441245124612471248124912501251125212531254125512561257125812591260126112621263126412651266126712681269127012711272127312741275127612771278127912801281128212831284128512861287128812891290129112921293129412951296129712981299130013011302130313041305130613071308130913101311131213131314131513161317131813191320132113221323132413251326132713281329133013311332133313341335133613371338133913401341134213431344134513461347134813491350135113521353135413551356135713581359136013611362136313641365136613671368136913701371137213731374137513761377137813791380138113821383138413851386138713881389139013911392139313941395139613971398139914001401140214031404140514061407140814091410141114121413141414151416141714181419142014211422142314241425142614271428142914301431143214331434143514361437143814391440144114421443144414451446144714481449145014511452145314541455145614571458145914601461146214631464146514661467146814691470147114721473147414751476147714781479148014811482148314841485148614871488148914901491149214931494149514961497149814991500150115021503150415051506150715081509151015111512151315141515151615171518151915201521152215231524152515261527152815291530153115321533153415351536153715381539154015411542154315441545154615471548154915501551155215531554155515561557155815591560156115621563156415651566156715681569157015711572157315741575157615771578157915801581158215831584158515861587158815891590159115921593159415951596159715981599160016011602160316041605160616071608160916101611161216131614161516161617161816191620162116221623162416251626162716281629163016311632163316341635163616371638163916401641164216431644164516461647164816491650165116521653165416551656165716581659166016611662166316641665166616671668166916701671167216731674167516761677167816791680168116821683168416851686168716881689169016911692169316941695169616971698169917001701170217031704170517061707170817091710171117121713171417151716171717181719172017211722172317241725172617271728172917301731173217331734173517361737173817391740174117421743174417451746174717481749175017511752175317541755175617571758175917601761176217631764176517661767176817691770177117721773177417751776177717781779178017811782178317841785178617871788178917901791179217931794179517961797179817991800180118021803180418051806180718081809181018111812181318141815181618171818181918201821182218231824182518261827182818291830183118321833183418351836183718381839184018411842184318441845184618471848184918501851185218531854185518561857185818591860186118621863186418651866186718681869187018711872187318741875187618771878187918801881188218831884188518861887188818891890189118921893189418951896189718981899190019011902190319041905190619071908190919101911191219131914191519161917191819191920192119221923192419251926192719281929193019311932193319341935193619371938193919401941194219431944194519461947194819491950195119521953195419551956195719581959196019611962196319641965196619671968196919701971197219731974197519761977197819791980198119821983198419851986198719881989199019911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019202020212022202320242025202620272028202920302031203220332034203520362037203820392040204120422043204420452046204720482049205020512052205320542055205620572058205920602061206220632064206520662067206820692070207120722073207420752076207720782079208020812082208320842085208620872088208920902091209220932094209520962097209820992100210121022103210421052106210721082109211021112112211321142115211621172118211921202121212221232124212521262127212821292130213121322133213421352136213721382139214021412142214321442145214621472148214921502151215221532154215521562157215821592160216121622163216421652166216721682169217021712172217321742175217621772178217921802181218221832184218521862187218821892190219121922193219421952196219721982199220022012202220322042205220622072208220922102211221222132214221522162217221822192220222122222223222422252226222722282229223022312232223322342235223622372238223922402241224222432244224522462247224822492250225122522253225422552256225722582259226022612262226322642265226622672268226922702271227222732274227522762277227822792280228122822283228422852286228722882289229022912292229322942295229622972298229923002301230223032304230523062307230823092310231123122313231423152316231723182319232023212322232323242325232623272328232923302331233223332334233523362337233823392340234123422343234423452346234723482349235023512352235323542355235623572358 |
- /*
- * random.c -- A strong random number generator
- *
- * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
- * Rights Reserved.
- *
- * Copyright Matt Mackall <mpm@selenic.com>, 2003, 2004, 2005
- *
- * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All
- * rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, and the entire permission notice in its entirety,
- * including the disclaimer of warranties.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * ALTERNATIVELY, this product may be distributed under the terms of
- * the GNU General Public License, in which case the provisions of the GPL are
- * required INSTEAD OF the above restrictions. (This clause is
- * necessary due to a potential bad interaction between the GPL and
- * the restrictions contained in a BSD-style copyright.)
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
- * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
- * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
- * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
- * DAMAGE.
- */
- /*
- * (now, with legal B.S. out of the way.....)
- *
- * This routine gathers environmental noise from device drivers, etc.,
- * and returns good random numbers, suitable for cryptographic use.
- * Besides the obvious cryptographic uses, these numbers are also good
- * for seeding TCP sequence numbers, and other places where it is
- * desirable to have numbers which are not only random, but hard to
- * predict by an attacker.
- *
- * Theory of operation
- * ===================
- *
- * Computers are very predictable devices. Hence it is extremely hard
- * to produce truly random numbers on a computer --- as opposed to
- * pseudo-random numbers, which can easily generated by using a
- * algorithm. Unfortunately, it is very easy for attackers to guess
- * the sequence of pseudo-random number generators, and for some
- * applications this is not acceptable. So instead, we must try to
- * gather "environmental noise" from the computer's environment, which
- * must be hard for outside attackers to observe, and use that to
- * generate random numbers. In a Unix environment, this is best done
- * from inside the kernel.
- *
- * Sources of randomness from the environment include inter-keyboard
- * timings, inter-interrupt timings from some interrupts, and other
- * events which are both (a) non-deterministic and (b) hard for an
- * outside observer to measure. Randomness from these sources are
- * added to an "entropy pool", which is mixed using a CRC-like function.
- * This is not cryptographically strong, but it is adequate assuming
- * the randomness is not chosen maliciously, and it is fast enough that
- * the overhead of doing it on every interrupt is very reasonable.
- * As random bytes are mixed into the entropy pool, the routines keep
- * an *estimate* of how many bits of randomness have been stored into
- * the random number generator's internal state.
- *
- * When random bytes are desired, they are obtained by taking the SHA
- * hash of the contents of the "entropy pool". The SHA hash avoids
- * exposing the internal state of the entropy pool. It is believed to
- * be computationally infeasible to derive any useful information
- * about the input of SHA from its output. Even if it is possible to
- * analyze SHA in some clever way, as long as the amount of data
- * returned from the generator is less than the inherent entropy in
- * the pool, the output data is totally unpredictable. For this
- * reason, the routine decreases its internal estimate of how many
- * bits of "true randomness" are contained in the entropy pool as it
- * outputs random numbers.
- *
- * If this estimate goes to zero, the routine can still generate
- * random numbers; however, an attacker may (at least in theory) be
- * able to infer the future output of the generator from prior
- * outputs. This requires successful cryptanalysis of SHA, which is
- * not believed to be feasible, but there is a remote possibility.
- * Nonetheless, these numbers should be useful for the vast majority
- * of purposes.
- *
- * Exported interfaces ---- output
- * ===============================
- *
- * There are four exported interfaces; two for use within the kernel,
- * and two or use from userspace.
- *
- * Exported interfaces ---- userspace output
- * -----------------------------------------
- *
- * The userspace interfaces are two character devices /dev/random and
- * /dev/urandom. /dev/random is suitable for use when very high
- * quality randomness is desired (for example, for key generation or
- * one-time pads), as it will only return a maximum of the number of
- * bits of randomness (as estimated by the random number generator)
- * contained in the entropy pool.
- *
- * The /dev/urandom device does not have this limit, and will return
- * as many bytes as are requested. As more and more random bytes are
- * requested without giving time for the entropy pool to recharge,
- * this will result in random numbers that are merely cryptographically
- * strong. For many applications, however, this is acceptable.
- *
- * Exported interfaces ---- kernel output
- * --------------------------------------
- *
- * The primary kernel interface is
- *
- * void get_random_bytes(void *buf, int nbytes);
- *
- * This interface will return the requested number of random bytes,
- * and place it in the requested buffer. This is equivalent to a
- * read from /dev/urandom.
- *
- * For less critical applications, there are the functions:
- *
- * u32 get_random_u32()
- * u64 get_random_u64()
- * unsigned int get_random_int()
- * unsigned long get_random_long()
- *
- * These are produced by a cryptographic RNG seeded from get_random_bytes,
- * and so do not deplete the entropy pool as much. These are recommended
- * for most in-kernel operations *if the result is going to be stored in
- * the kernel*.
- *
- * Specifically, the get_random_int() family do not attempt to do
- * "anti-backtracking". If you capture the state of the kernel (e.g.
- * by snapshotting the VM), you can figure out previous get_random_int()
- * return values. But if the value is stored in the kernel anyway,
- * this is not a problem.
- *
- * It *is* safe to expose get_random_int() output to attackers (e.g. as
- * network cookies); given outputs 1..n, it's not feasible to predict
- * outputs 0 or n+1. The only concern is an attacker who breaks into
- * the kernel later; the get_random_int() engine is not reseeded as
- * often as the get_random_bytes() one.
- *
- * get_random_bytes() is needed for keys that need to stay secret after
- * they are erased from the kernel. For example, any key that will
- * be wrapped and stored encrypted. And session encryption keys: we'd
- * like to know that after the session is closed and the keys erased,
- * the plaintext is unrecoverable to someone who recorded the ciphertext.
- *
- * But for network ports/cookies, stack canaries, PRNG seeds, address
- * space layout randomization, session *authentication* keys, or other
- * applications where the sensitive data is stored in the kernel in
- * plaintext for as long as it's sensitive, the get_random_int() family
- * is just fine.
- *
- * Consider ASLR. We want to keep the address space secret from an
- * outside attacker while the process is running, but once the address
- * space is torn down, it's of no use to an attacker any more. And it's
- * stored in kernel data structures as long as it's alive, so worrying
- * about an attacker's ability to extrapolate it from the get_random_int()
- * CRNG is silly.
- *
- * Even some cryptographic keys are safe to generate with get_random_int().
- * In particular, keys for SipHash are generally fine. Here, knowledge
- * of the key authorizes you to do something to a kernel object (inject
- * packets to a network connection, or flood a hash table), and the
- * key is stored with the object being protected. Once it goes away,
- * we no longer care if anyone knows the key.
- *
- * prandom_u32()
- * -------------
- *
- * For even weaker applications, see the pseudorandom generator
- * prandom_u32(), prandom_max(), and prandom_bytes(). If the random
- * numbers aren't security-critical at all, these are *far* cheaper.
- * Useful for self-tests, random error simulation, randomized backoffs,
- * and any other application where you trust that nobody is trying to
- * maliciously mess with you by guessing the "random" numbers.
- *
- * Exported interfaces ---- input
- * ==============================
- *
- * The current exported interfaces for gathering environmental noise
- * from the devices are:
- *
- * void add_device_randomness(const void *buf, unsigned int size);
- * void add_input_randomness(unsigned int type, unsigned int code,
- * unsigned int value);
- * void add_interrupt_randomness(int irq, int irq_flags);
- * void add_disk_randomness(struct gendisk *disk);
- *
- * add_device_randomness() is for adding data to the random pool that
- * is likely to differ between two devices (or possibly even per boot).
- * This would be things like MAC addresses or serial numbers, or the
- * read-out of the RTC. This does *not* add any actual entropy to the
- * pool, but it initializes the pool to different values for devices
- * that might otherwise be identical and have very little entropy
- * available to them (particularly common in the embedded world).
- *
- * add_input_randomness() uses the input layer interrupt timing, as well as
- * the event type information from the hardware.
- *
- * add_interrupt_randomness() uses the interrupt timing as random
- * inputs to the entropy pool. Using the cycle counters and the irq source
- * as inputs, it feeds the randomness roughly once a second.
- *
- * add_disk_randomness() uses what amounts to the seek time of block
- * layer request events, on a per-disk_devt basis, as input to the
- * entropy pool. Note that high-speed solid state drives with very low
- * seek times do not make for good sources of entropy, as their seek
- * times are usually fairly consistent.
- *
- * All of these routines try to estimate how many bits of randomness a
- * particular randomness source. They do this by keeping track of the
- * first and second order deltas of the event timings.
- *
- * Ensuring unpredictability at system startup
- * ============================================
- *
- * When any operating system starts up, it will go through a sequence
- * of actions that are fairly predictable by an adversary, especially
- * if the start-up does not involve interaction with a human operator.
- * This reduces the actual number of bits of unpredictability in the
- * entropy pool below the value in entropy_count. In order to
- * counteract this effect, it helps to carry information in the
- * entropy pool across shut-downs and start-ups. To do this, put the
- * following lines an appropriate script which is run during the boot
- * sequence:
- *
- * echo "Initializing random number generator..."
- * random_seed=/var/run/random-seed
- * # Carry a random seed from start-up to start-up
- * # Load and then save the whole entropy pool
- * if [ -f $random_seed ]; then
- * cat $random_seed >/dev/urandom
- * else
- * touch $random_seed
- * fi
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * and the following lines in an appropriate script which is run as
- * the system is shutdown:
- *
- * # Carry a random seed from shut-down to start-up
- * # Save the whole entropy pool
- * echo "Saving random seed..."
- * random_seed=/var/run/random-seed
- * touch $random_seed
- * chmod 600 $random_seed
- * dd if=/dev/urandom of=$random_seed count=1 bs=512
- *
- * For example, on most modern systems using the System V init
- * scripts, such code fragments would be found in
- * /etc/rc.d/init.d/random. On older Linux systems, the correct script
- * location might be in /etc/rcb.d/rc.local or /etc/rc.d/rc.0.
- *
- * Effectively, these commands cause the contents of the entropy pool
- * to be saved at shut-down time and reloaded into the entropy pool at
- * start-up. (The 'dd' in the addition to the bootup script is to
- * make sure that /etc/random-seed is different for every start-up,
- * even if the system crashes without executing rc.0.) Even with
- * complete knowledge of the start-up activities, predicting the state
- * of the entropy pool requires knowledge of the previous history of
- * the system.
- *
- * Configuring the /dev/random driver under Linux
- * ==============================================
- *
- * The /dev/random driver under Linux uses minor numbers 8 and 9 of
- * the /dev/mem major number (#1). So if your system does not have
- * /dev/random and /dev/urandom created already, they can be created
- * by using the commands:
- *
- * mknod /dev/random c 1 8
- * mknod /dev/urandom c 1 9
- *
- * Acknowledgements:
- * =================
- *
- * Ideas for constructing this random number generator were derived
- * from Pretty Good Privacy's random number generator, and from private
- * discussions with Phil Karn. Colin Plumb provided a faster random
- * number generator, which speed up the mixing function of the entropy
- * pool, taken from PGPfone. Dale Worley has also contributed many
- * useful ideas and suggestions to improve this driver.
- *
- * Any flaws in the design are solely my responsibility, and should
- * not be attributed to the Phil, Colin, or any of authors of PGP.
- *
- * Further background information on this topic may be obtained from
- * RFC 1750, "Randomness Recommendations for Security", by Donald
- * Eastlake, Steve Crocker, and Jeff Schiller.
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/utsname.h>
- #include <linux/module.h>
- #include <linux/kernel.h>
- #include <linux/major.h>
- #include <linux/string.h>
- #include <linux/fcntl.h>
- #include <linux/slab.h>
- #include <linux/random.h>
- #include <linux/poll.h>
- #include <linux/init.h>
- #include <linux/fs.h>
- #include <linux/genhd.h>
- #include <linux/interrupt.h>
- #include <linux/mm.h>
- #include <linux/nodemask.h>
- #include <linux/spinlock.h>
- #include <linux/kthread.h>
- #include <linux/percpu.h>
- #include <linux/fips.h>
- #include <linux/ptrace.h>
- #include <linux/workqueue.h>
- #include <linux/irq.h>
- #include <linux/ratelimit.h>
- #include <linux/syscalls.h>
- #include <linux/completion.h>
- #include <linux/uuid.h>
- #include <crypto/chacha.h>
- #include <crypto/sha.h>
- #include <asm/processor.h>
- #include <linux/uaccess.h>
- #include <asm/irq.h>
- #include <asm/irq_regs.h>
- #include <asm/io.h>
- #define CREATE_TRACE_POINTS
- #include <trace/events/random.h>
- /* #define ADD_INTERRUPT_BENCH */
- /*
- * Configuration information
- */
- #define INPUT_POOL_SHIFT 12
- #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5))
- #define OUTPUT_POOL_SHIFT 10
- #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5))
- #define EXTRACT_SIZE 10
- #define LONGS(x) (((x) + sizeof(unsigned long) - 1)/sizeof(unsigned long))
- /*
- * To allow fractional bits to be tracked, the entropy_count field is
- * denominated in units of 1/8th bits.
- *
- * 2*(ENTROPY_SHIFT + poolbitshift) must <= 31, or the multiply in
- * credit_entropy_bits() needs to be 64 bits wide.
- */
- #define ENTROPY_SHIFT 3
- #define ENTROPY_BITS(r) ((r)->entropy_count >> ENTROPY_SHIFT)
- /*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
- static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
- /*
- * Originally, we used a primitive polynomial of degree .poolwords
- * over GF(2). The taps for various sizes are defined below. They
- * were chosen to be evenly spaced except for the last tap, which is 1
- * to get the twisting happening as fast as possible.
- *
- * For the purposes of better mixing, we use the CRC-32 polynomial as
- * well to make a (modified) twisted Generalized Feedback Shift
- * Register. (See M. Matsumoto & Y. Kurita, 1992. Twisted GFSR
- * generators. ACM Transactions on Modeling and Computer Simulation
- * 2(3):179-194. Also see M. Matsumoto & Y. Kurita, 1994. Twisted
- * GFSR generators II. ACM Transactions on Modeling and Computer
- * Simulation 4:254-266)
- *
- * Thanks to Colin Plumb for suggesting this.
- *
- * The mixing operation is much less sensitive than the output hash,
- * where we use SHA-1. All that we want of mixing operation is that
- * it be a good non-cryptographic hash; i.e. it not produce collisions
- * when fed "random" data of the sort we expect to see. As long as
- * the pool state differs for different inputs, we have preserved the
- * input entropy and done a good job. The fact that an intelligent
- * attacker can construct inputs that will produce controlled
- * alterations to the pool's state is not important because we don't
- * consider such inputs to contribute any randomness. The only
- * property we need with respect to them is that the attacker can't
- * increase his/her knowledge of the pool's state. Since all
- * additions are reversible (knowing the final state and the input,
- * you can reconstruct the initial state), if an attacker has any
- * uncertainty about the initial state, he/she can only shuffle that
- * uncertainty about, but never cause any collisions (which would
- * decrease the uncertainty).
- *
- * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
- * Videau in their paper, "The Linux Pseudorandom Number Generator
- * Revisited" (see: http://eprint.iacr.org/2012/251.pdf). In their
- * paper, they point out that we are not using a true Twisted GFSR,
- * since Matsumoto & Kurita used a trinomial feedback polynomial (that
- * is, with only three taps, instead of the six that we are using).
- * As a result, the resulting polynomial is neither primitive nor
- * irreducible, and hence does not have a maximal period over
- * GF(2**32). They suggest a slight change to the generator
- * polynomial which improves the resulting TGFSR polynomial to be
- * irreducible, which we have made here.
- */
- static const struct poolinfo {
- int poolbitshift, poolwords, poolbytes, poolfracbits;
- #define S(x) ilog2(x)+5, (x), (x)*4, (x) << (ENTROPY_SHIFT+5)
- int tap1, tap2, tap3, tap4, tap5;
- } poolinfo_table[] = {
- /* was: x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 */
- /* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
- { S(128), 104, 76, 51, 25, 1 },
- };
- /*
- * Static global variables
- */
- static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
- static struct fasync_struct *fasync;
- static DEFINE_SPINLOCK(random_ready_list_lock);
- static LIST_HEAD(random_ready_list);
- struct crng_state {
- __u32 state[16];
- unsigned long init_time;
- spinlock_t lock;
- };
- static struct crng_state primary_crng = {
- .lock = __SPIN_LOCK_UNLOCKED(primary_crng.lock),
- };
- /*
- * crng_init = 0 --> Uninitialized
- * 1 --> Initialized
- * 2 --> Initialized from input_pool
- *
- * crng_init is protected by primary_crng->lock, and only increases
- * its value (from 0->1->2).
- */
- static int crng_init = 0;
- static bool crng_need_final_init = false;
- #define crng_ready() (likely(crng_init > 1))
- static int crng_init_cnt = 0;
- static unsigned long crng_global_init_time = 0;
- #define CRNG_INIT_CNT_THRESH (2*CHACHA_KEY_SIZE)
- static void _extract_crng(struct crng_state *crng, __u8 out[CHACHA_BLOCK_SIZE]);
- static void _crng_backtrack_protect(struct crng_state *crng,
- __u8 tmp[CHACHA_BLOCK_SIZE], int used);
- static void process_random_ready_list(void);
- static void _get_random_bytes(void *buf, int nbytes);
- static struct ratelimit_state unseeded_warning =
- RATELIMIT_STATE_INIT("warn_unseeded_randomness", HZ, 3);
- static struct ratelimit_state urandom_warning =
- RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3);
- static int ratelimit_disable __read_mostly;
- module_param_named(ratelimit_disable, ratelimit_disable, int, 0644);
- MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
- /**********************************************************************
- *
- * OS independent entropy store. Here are the functions which handle
- * storing entropy in an entropy pool.
- *
- **********************************************************************/
- struct entropy_store;
- struct entropy_store {
- /* read-only data: */
- const struct poolinfo *poolinfo;
- __u32 *pool;
- const char *name;
- /* read-write data: */
- spinlock_t lock;
- unsigned short add_ptr;
- unsigned short input_rotate;
- int entropy_count;
- unsigned int initialized:1;
- unsigned int last_data_init:1;
- __u8 last_data[EXTRACT_SIZE];
- };
- static ssize_t extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int min, int rsvd);
- static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips);
- static void crng_reseed(struct crng_state *crng, struct entropy_store *r);
- static __u32 input_pool_data[INPUT_POOL_WORDS] __latent_entropy;
- static struct entropy_store input_pool = {
- .poolinfo = &poolinfo_table[0],
- .name = "input",
- .lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
- .pool = input_pool_data
- };
- static __u32 const twist_table[8] = {
- 0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
- 0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
- /*
- * This function adds bytes into the entropy "pool". It does not
- * update the entropy estimate. The caller should call
- * credit_entropy_bits if this is appropriate.
- *
- * The pool is stirred with a primitive polynomial of the appropriate
- * degree, and then twisted. We twist by three bits at a time because
- * it's cheap to do so and helps slightly in the expected case where
- * the entropy is concentrated in the low-order bits.
- */
- static void _mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
- {
- unsigned long i, tap1, tap2, tap3, tap4, tap5;
- int input_rotate;
- int wordmask = r->poolinfo->poolwords - 1;
- const char *bytes = in;
- __u32 w;
- tap1 = r->poolinfo->tap1;
- tap2 = r->poolinfo->tap2;
- tap3 = r->poolinfo->tap3;
- tap4 = r->poolinfo->tap4;
- tap5 = r->poolinfo->tap5;
- input_rotate = r->input_rotate;
- i = r->add_ptr;
- /* mix one byte at a time to simplify size handling and churn faster */
- while (nbytes--) {
- w = rol32(*bytes++, input_rotate);
- i = (i - 1) & wordmask;
- /* XOR in the various taps */
- w ^= r->pool[i];
- w ^= r->pool[(i + tap1) & wordmask];
- w ^= r->pool[(i + tap2) & wordmask];
- w ^= r->pool[(i + tap3) & wordmask];
- w ^= r->pool[(i + tap4) & wordmask];
- w ^= r->pool[(i + tap5) & wordmask];
- /* Mix the result back in with a twist */
- r->pool[i] = (w >> 3) ^ twist_table[w & 7];
- /*
- * Normally, we add 7 bits of rotation to the pool.
- * At the beginning of the pool, add an extra 7 bits
- * rotation, so that successive passes spread the
- * input bits across the pool evenly.
- */
- input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
- }
- r->input_rotate = input_rotate;
- r->add_ptr = i;
- }
- static void __mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
- {
- trace_mix_pool_bytes_nolock(r->name, nbytes, _RET_IP_);
- _mix_pool_bytes(r, in, nbytes);
- }
- static void mix_pool_bytes(struct entropy_store *r, const void *in,
- int nbytes)
- {
- unsigned long flags;
- trace_mix_pool_bytes(r->name, nbytes, _RET_IP_);
- spin_lock_irqsave(&r->lock, flags);
- _mix_pool_bytes(r, in, nbytes);
- spin_unlock_irqrestore(&r->lock, flags);
- }
- struct fast_pool {
- __u32 pool[4];
- unsigned long last;
- unsigned short reg_idx;
- unsigned char count;
- };
- /*
- * This is a fast mixing routine used by the interrupt randomness
- * collector. It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
- */
- static void fast_mix(struct fast_pool *f)
- {
- __u32 a = f->pool[0], b = f->pool[1];
- __u32 c = f->pool[2], d = f->pool[3];
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
- a += b; c += d;
- b = rol32(b, 6); d = rol32(d, 27);
- d ^= a; b ^= c;
- a += b; c += d;
- b = rol32(b, 16); d = rol32(d, 14);
- d ^= a; b ^= c;
- f->pool[0] = a; f->pool[1] = b;
- f->pool[2] = c; f->pool[3] = d;
- f->count++;
- }
- static void process_random_ready_list(void)
- {
- unsigned long flags;
- struct random_ready_callback *rdy, *tmp;
- spin_lock_irqsave(&random_ready_list_lock, flags);
- list_for_each_entry_safe(rdy, tmp, &random_ready_list, list) {
- struct module *owner = rdy->owner;
- list_del_init(&rdy->list);
- rdy->func(rdy);
- module_put(owner);
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
- }
- /*
- * Credit (or debit) the entropy store with n bits of entropy.
- * Use credit_entropy_bits_safe() if the value comes from userspace
- * or otherwise should be checked for extreme values.
- */
- static void credit_entropy_bits(struct entropy_store *r, int nbits)
- {
- int entropy_count, orig, has_initialized = 0;
- const int pool_size = r->poolinfo->poolfracbits;
- int nfrac = nbits << ENTROPY_SHIFT;
- if (!nbits)
- return;
- retry:
- entropy_count = orig = READ_ONCE(r->entropy_count);
- if (nfrac < 0) {
- /* Debit */
- entropy_count += nfrac;
- } else {
- /*
- * Credit: we have to account for the possibility of
- * overwriting already present entropy. Even in the
- * ideal case of pure Shannon entropy, new contributions
- * approach the full value asymptotically:
- *
- * entropy <- entropy + (pool_size - entropy) *
- * (1 - exp(-add_entropy/pool_size))
- *
- * For add_entropy <= pool_size/2 then
- * (1 - exp(-add_entropy/pool_size)) >=
- * (add_entropy/pool_size)*0.7869...
- * so we can approximate the exponential with
- * 3/4*add_entropy/pool_size and still be on the
- * safe side by adding at most pool_size/2 at a time.
- *
- * The use of pool_size-2 in the while statement is to
- * prevent rounding artifacts from making the loop
- * arbitrarily long; this limits the loop to log2(pool_size)*2
- * turns no matter how large nbits is.
- */
- int pnfrac = nfrac;
- const int s = r->poolinfo->poolbitshift + ENTROPY_SHIFT + 2;
- /* The +2 corresponds to the /4 in the denominator */
- do {
- unsigned int anfrac = min(pnfrac, pool_size/2);
- unsigned int add =
- ((pool_size - entropy_count)*anfrac*3) >> s;
- entropy_count += add;
- pnfrac -= anfrac;
- } while (unlikely(entropy_count < pool_size-2 && pnfrac));
- }
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy/overflow: pool %s count %d\n",
- r->name, entropy_count);
- entropy_count = 0;
- } else if (entropy_count > pool_size)
- entropy_count = pool_size;
- if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
- goto retry;
- if (has_initialized) {
- r->initialized = 1;
- kill_fasync(&fasync, SIGIO, POLL_IN);
- }
- trace_credit_entropy_bits(r->name, nbits,
- entropy_count >> ENTROPY_SHIFT, _RET_IP_);
- if (r == &input_pool) {
- int entropy_bits = entropy_count >> ENTROPY_SHIFT;
- if (crng_init < 2) {
- if (entropy_bits < 128)
- return;
- crng_reseed(&primary_crng, r);
- entropy_bits = ENTROPY_BITS(r);
- }
- }
- }
- static int credit_entropy_bits_safe(struct entropy_store *r, int nbits)
- {
- const int nbits_max = r->poolinfo->poolwords * 32;
- if (nbits < 0)
- return -EINVAL;
- /* Cap the value to avoid overflows */
- nbits = min(nbits, nbits_max);
- credit_entropy_bits(r, nbits);
- return 0;
- }
- /*********************************************************************
- *
- * CRNG using CHACHA20
- *
- *********************************************************************/
- #define CRNG_RESEED_INTERVAL (300*HZ)
- static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
- #ifdef CONFIG_NUMA
- /*
- * Hack to deal with crazy userspace progams when they are all trying
- * to access /dev/urandom in parallel. The programs are almost
- * certainly doing something terribly wrong, but we'll work around
- * their brain damage.
- */
- static struct crng_state **crng_node_pool __read_mostly;
- #endif
- static void invalidate_batched_entropy(void);
- static void numa_crng_init(void);
- static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU);
- static int __init parse_trust_cpu(char *arg)
- {
- return kstrtobool(arg, &trust_cpu);
- }
- early_param("random.trust_cpu", parse_trust_cpu);
- static bool crng_init_try_arch(struct crng_state *crng)
- {
- int i;
- bool arch_init = true;
- unsigned long rv;
- for (i = 4; i < 16; i++) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv)) {
- rv = random_get_entropy();
- arch_init = false;
- }
- crng->state[i] ^= rv;
- }
- return arch_init;
- }
- static bool __init crng_init_try_arch_early(struct crng_state *crng)
- {
- int i;
- bool arch_init = true;
- unsigned long rv;
- for (i = 4; i < 16; i++) {
- if (!arch_get_random_seed_long_early(&rv) &&
- !arch_get_random_long_early(&rv)) {
- rv = random_get_entropy();
- arch_init = false;
- }
- crng->state[i] ^= rv;
- }
- return arch_init;
- }
- static void __maybe_unused crng_initialize_secondary(struct crng_state *crng)
- {
- chacha_init_consts(crng->state);
- _get_random_bytes(&crng->state[4], sizeof(__u32) * 12);
- crng_init_try_arch(crng);
- crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
- }
- static void __init crng_initialize_primary(struct crng_state *crng)
- {
- chacha_init_consts(crng->state);
- _extract_entropy(&input_pool, &crng->state[4], sizeof(__u32) * 12, 0);
- if (crng_init_try_arch_early(crng) && trust_cpu) {
- invalidate_batched_entropy();
- numa_crng_init();
- crng_init = 2;
- pr_notice("crng done (trusting CPU's manufacturer)\n");
- }
- crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
- }
- static void crng_finalize_init(struct crng_state *crng)
- {
- if (crng != &primary_crng || crng_init >= 2)
- return;
- if (!system_wq) {
- /* We can't call numa_crng_init until we have workqueues,
- * so mark this for processing later. */
- crng_need_final_init = true;
- return;
- }
- invalidate_batched_entropy();
- numa_crng_init();
- crng_init = 2;
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
- }
- #ifdef CONFIG_NUMA
- static void do_numa_crng_init(struct work_struct *work)
- {
- int i;
- struct crng_state *crng;
- struct crng_state **pool;
- pool = kcalloc(nr_node_ids, sizeof(*pool), GFP_KERNEL|__GFP_NOFAIL);
- for_each_online_node(i) {
- crng = kmalloc_node(sizeof(struct crng_state),
- GFP_KERNEL | __GFP_NOFAIL, i);
- spin_lock_init(&crng->lock);
- crng_initialize_secondary(crng);
- pool[i] = crng;
- }
- /* pairs with READ_ONCE() in select_crng() */
- if (cmpxchg_release(&crng_node_pool, NULL, pool) != NULL) {
- for_each_node(i)
- kfree(pool[i]);
- kfree(pool);
- }
- }
- static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
- static void numa_crng_init(void)
- {
- schedule_work(&numa_crng_init_work);
- }
- static struct crng_state *select_crng(void)
- {
- struct crng_state **pool;
- int nid = numa_node_id();
- /* pairs with cmpxchg_release() in do_numa_crng_init() */
- pool = READ_ONCE(crng_node_pool);
- if (pool && pool[nid])
- return pool[nid];
- return &primary_crng;
- }
- #else
- static void numa_crng_init(void) {}
- static struct crng_state *select_crng(void)
- {
- return &primary_crng;
- }
- #endif
- /*
- * crng_fast_load() can be called by code in the interrupt service
- * path. So we can't afford to dilly-dally. Returns the number of
- * bytes processed from cp.
- */
- static size_t crng_fast_load(const char *cp, size_t len)
- {
- unsigned long flags;
- char *p;
- size_t ret = 0;
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
- return 0;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 0;
- }
- p = (unsigned char *) &primary_crng.state[4];
- while (len > 0 && crng_init_cnt < CRNG_INIT_CNT_THRESH) {
- p[crng_init_cnt % CHACHA_KEY_SIZE] ^= *cp;
- cp++; crng_init_cnt++; len--; ret++;
- }
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {
- invalidate_batched_entropy();
- crng_init = 1;
- pr_notice("fast init done\n");
- }
- return ret;
- }
- /*
- * crng_slow_load() is called by add_device_randomness, which has two
- * attributes. (1) We can't trust the buffer passed to it is
- * guaranteed to be unpredictable (so it might not have any entropy at
- * all), and (2) it doesn't have the performance constraints of
- * crng_fast_load().
- *
- * So we do something more comprehensive which is guaranteed to touch
- * all of the primary_crng's state, and which uses a LFSR with a
- * period of 255 as part of the mixing algorithm. Finally, we do
- * *not* advance crng_init_cnt since buffer we may get may be something
- * like a fixed DMI table (for example), which might very well be
- * unique to the machine, but is otherwise unvarying.
- */
- static int crng_slow_load(const char *cp, size_t len)
- {
- unsigned long flags;
- static unsigned char lfsr = 1;
- unsigned char tmp;
- unsigned i, max = CHACHA_KEY_SIZE;
- const char * src_buf = cp;
- char * dest_buf = (char *) &primary_crng.state[4];
- if (!spin_trylock_irqsave(&primary_crng.lock, flags))
- return 0;
- if (crng_init != 0) {
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 0;
- }
- if (len > max)
- max = len;
- for (i = 0; i < max ; i++) {
- tmp = lfsr;
- lfsr >>= 1;
- if (tmp & 1)
- lfsr ^= 0xE1;
- tmp = dest_buf[i % CHACHA_KEY_SIZE];
- dest_buf[i % CHACHA_KEY_SIZE] ^= src_buf[i % len] ^ lfsr;
- lfsr += (tmp << 3) | (tmp >> 5);
- }
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- return 1;
- }
- static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
- {
- unsigned long flags;
- int i, num;
- union {
- __u8 block[CHACHA_BLOCK_SIZE];
- __u32 key[8];
- } buf;
- if (r) {
- num = extract_entropy(r, &buf, 32, 16, 0);
- if (num == 0)
- return;
- } else {
- _extract_crng(&primary_crng, buf.block);
- _crng_backtrack_protect(&primary_crng, buf.block,
- CHACHA_KEY_SIZE);
- }
- spin_lock_irqsave(&crng->lock, flags);
- for (i = 0; i < 8; i++) {
- unsigned long rv;
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- crng->state[i+4] ^= buf.key[i] ^ rv;
- }
- memzero_explicit(&buf, sizeof(buf));
- WRITE_ONCE(crng->init_time, jiffies);
- spin_unlock_irqrestore(&crng->lock, flags);
- crng_finalize_init(crng);
- }
- static void _extract_crng(struct crng_state *crng,
- __u8 out[CHACHA_BLOCK_SIZE])
- {
- unsigned long v, flags, init_time;
- if (crng_ready()) {
- init_time = READ_ONCE(crng->init_time);
- if (time_after(READ_ONCE(crng_global_init_time), init_time) ||
- time_after(jiffies, init_time + CRNG_RESEED_INTERVAL))
- crng_reseed(crng, crng == &primary_crng ?
- &input_pool : NULL);
- }
- spin_lock_irqsave(&crng->lock, flags);
- if (arch_get_random_long(&v))
- crng->state[14] ^= v;
- chacha20_block(&crng->state[0], out);
- if (crng->state[12] == 0)
- crng->state[13]++;
- spin_unlock_irqrestore(&crng->lock, flags);
- }
- static void extract_crng(__u8 out[CHACHA_BLOCK_SIZE])
- {
- _extract_crng(select_crng(), out);
- }
- /*
- * Use the leftover bytes from the CRNG block output (if there is
- * enough) to mutate the CRNG key to provide backtracking protection.
- */
- static void _crng_backtrack_protect(struct crng_state *crng,
- __u8 tmp[CHACHA_BLOCK_SIZE], int used)
- {
- unsigned long flags;
- __u32 *s, *d;
- int i;
- used = round_up(used, sizeof(__u32));
- if (used + CHACHA_KEY_SIZE > CHACHA_BLOCK_SIZE) {
- extract_crng(tmp);
- used = 0;
- }
- spin_lock_irqsave(&crng->lock, flags);
- s = (__u32 *) &tmp[used];
- d = &crng->state[4];
- for (i=0; i < 8; i++)
- *d++ ^= *s++;
- spin_unlock_irqrestore(&crng->lock, flags);
- }
- static void crng_backtrack_protect(__u8 tmp[CHACHA_BLOCK_SIZE], int used)
- {
- _crng_backtrack_protect(select_crng(), tmp, used);
- }
- static ssize_t extract_crng_user(void __user *buf, size_t nbytes)
- {
- ssize_t ret = 0, i = CHACHA_BLOCK_SIZE;
- __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
- int large_request = (nbytes > 256);
- while (nbytes) {
- if (large_request && need_resched()) {
- if (signal_pending(current)) {
- if (ret == 0)
- ret = -ERESTARTSYS;
- break;
- }
- schedule();
- }
- extract_crng(tmp);
- i = min_t(int, nbytes, CHACHA_BLOCK_SIZE);
- if (copy_to_user(buf, tmp, i)) {
- ret = -EFAULT;
- break;
- }
- nbytes -= i;
- buf += i;
- ret += i;
- }
- crng_backtrack_protect(tmp, i);
- /* Wipe data just written to memory */
- memzero_explicit(tmp, sizeof(tmp));
- return ret;
- }
- /*********************************************************************
- *
- * Entropy input management
- *
- *********************************************************************/
- /* There is one of these per entropy source */
- struct timer_rand_state {
- cycles_t last_time;
- long last_delta, last_delta2;
- };
- #define INIT_TIMER_RAND_STATE { INITIAL_JIFFIES, };
- /*
- * Add device- or boot-specific data to the input pool to help
- * initialize it.
- *
- * None of this adds any entropy; it is meant to avoid the problem of
- * the entropy pool having similar initial state across largely
- * identical devices.
- */
- void add_device_randomness(const void *buf, unsigned int size)
- {
- unsigned long time = random_get_entropy() ^ jiffies;
- unsigned long flags;
- if (!crng_ready() && size)
- crng_slow_load(buf, size);
- trace_add_device_randomness(size, _RET_IP_);
- spin_lock_irqsave(&input_pool.lock, flags);
- _mix_pool_bytes(&input_pool, buf, size);
- _mix_pool_bytes(&input_pool, &time, sizeof(time));
- spin_unlock_irqrestore(&input_pool.lock, flags);
- }
- EXPORT_SYMBOL(add_device_randomness);
- static struct timer_rand_state input_timer_state = INIT_TIMER_RAND_STATE;
- /*
- * This function adds entropy to the entropy "pool" by using timing
- * delays. It uses the timer_rand_state structure to make an estimate
- * of how many bits of entropy this call has added to the pool.
- *
- * The number "num" is also added to the pool - it should somehow describe
- * the type of event which just happened. This is currently 0-255 for
- * keyboard scan codes, and 256 upwards for interrupts.
- *
- */
- static void add_timer_randomness(struct timer_rand_state *state, unsigned num)
- {
- struct entropy_store *r;
- struct {
- long jiffies;
- unsigned cycles;
- unsigned num;
- } sample;
- long delta, delta2, delta3;
- sample.jiffies = jiffies;
- sample.cycles = random_get_entropy();
- sample.num = num;
- r = &input_pool;
- mix_pool_bytes(r, &sample, sizeof(sample));
- /*
- * Calculate number of bits of randomness we probably added.
- * We take into account the first, second and third-order deltas
- * in order to make our estimate.
- */
- delta = sample.jiffies - READ_ONCE(state->last_time);
- WRITE_ONCE(state->last_time, sample.jiffies);
- delta2 = delta - READ_ONCE(state->last_delta);
- WRITE_ONCE(state->last_delta, delta);
- delta3 = delta2 - READ_ONCE(state->last_delta2);
- WRITE_ONCE(state->last_delta2, delta2);
- if (delta < 0)
- delta = -delta;
- if (delta2 < 0)
- delta2 = -delta2;
- if (delta3 < 0)
- delta3 = -delta3;
- if (delta > delta2)
- delta = delta2;
- if (delta > delta3)
- delta = delta3;
- /*
- * delta is now minimum absolute delta.
- * Round down by 1 bit on general principles,
- * and limit entropy estimate to 12 bits.
- */
- credit_entropy_bits(r, min_t(int, fls(delta>>1), 11));
- }
- void add_input_randomness(unsigned int type, unsigned int code,
- unsigned int value)
- {
- static unsigned char last_value;
- /* ignore autorepeat and the like */
- if (value == last_value)
- return;
- last_value = value;
- add_timer_randomness(&input_timer_state,
- (type << 4) ^ code ^ (code >> 4) ^ value);
- trace_add_input_randomness(ENTROPY_BITS(&input_pool));
- }
- EXPORT_SYMBOL_GPL(add_input_randomness);
- static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
- #ifdef ADD_INTERRUPT_BENCH
- static unsigned long avg_cycles, avg_deviation;
- #define AVG_SHIFT 8 /* Exponential average factor k=1/256 */
- #define FIXED_1_2 (1 << (AVG_SHIFT-1))
- static void add_interrupt_bench(cycles_t start)
- {
- long delta = random_get_entropy() - start;
- /* Use a weighted moving average */
- delta = delta - ((avg_cycles + FIXED_1_2) >> AVG_SHIFT);
- avg_cycles += delta;
- /* And average deviation */
- delta = abs(delta) - ((avg_deviation + FIXED_1_2) >> AVG_SHIFT);
- avg_deviation += delta;
- }
- #else
- #define add_interrupt_bench(x)
- #endif
- static __u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
- {
- __u32 *ptr = (__u32 *) regs;
- unsigned int idx;
- if (regs == NULL)
- return 0;
- idx = READ_ONCE(f->reg_idx);
- if (idx >= sizeof(struct pt_regs) / sizeof(__u32))
- idx = 0;
- ptr += idx++;
- WRITE_ONCE(f->reg_idx, idx);
- return *ptr;
- }
- void add_interrupt_randomness(int irq, int irq_flags)
- {
- struct entropy_store *r;
- struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
- struct pt_regs *regs = get_irq_regs();
- unsigned long now = jiffies;
- cycles_t cycles = random_get_entropy();
- __u32 c_high, j_high;
- __u64 ip;
- unsigned long seed;
- int credit = 0;
- if (cycles == 0)
- cycles = get_reg(fast_pool, regs);
- c_high = (sizeof(cycles) > 4) ? cycles >> 32 : 0;
- j_high = (sizeof(now) > 4) ? now >> 32 : 0;
- fast_pool->pool[0] ^= cycles ^ j_high ^ irq;
- fast_pool->pool[1] ^= now ^ c_high;
- ip = regs ? instruction_pointer(regs) : _RET_IP_;
- fast_pool->pool[2] ^= ip;
- fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
- get_reg(fast_pool, regs);
- fast_mix(fast_pool);
- add_interrupt_bench(cycles);
- if (unlikely(crng_init == 0)) {
- if ((fast_pool->count >= 64) &&
- crng_fast_load((char *) fast_pool->pool,
- sizeof(fast_pool->pool)) > 0) {
- fast_pool->count = 0;
- fast_pool->last = now;
- }
- return;
- }
- if ((fast_pool->count < 64) &&
- !time_after(now, fast_pool->last + HZ))
- return;
- r = &input_pool;
- if (!spin_trylock(&r->lock))
- return;
- fast_pool->last = now;
- __mix_pool_bytes(r, &fast_pool->pool, sizeof(fast_pool->pool));
- /*
- * If we have architectural seed generator, produce a seed and
- * add it to the pool. For the sake of paranoia don't let the
- * architectural seed generator dominate the input from the
- * interrupt noise.
- */
- if (arch_get_random_seed_long(&seed)) {
- __mix_pool_bytes(r, &seed, sizeof(seed));
- credit = 1;
- }
- spin_unlock(&r->lock);
- fast_pool->count = 0;
- /* award one bit for the contents of the fast pool */
- credit_entropy_bits(r, credit + 1);
- }
- EXPORT_SYMBOL_GPL(add_interrupt_randomness);
- #ifdef CONFIG_BLOCK
- void add_disk_randomness(struct gendisk *disk)
- {
- if (!disk || !disk->random)
- return;
- /* first major is 1, so we get >= 0x200 here */
- add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
- trace_add_disk_randomness(disk_devt(disk), ENTROPY_BITS(&input_pool));
- }
- EXPORT_SYMBOL_GPL(add_disk_randomness);
- #endif
- /*********************************************************************
- *
- * Entropy extraction routines
- *
- *********************************************************************/
- /*
- * This function decides how many bytes to actually take from the
- * given pool, and also debits the entropy count accordingly.
- */
- static size_t account(struct entropy_store *r, size_t nbytes, int min,
- int reserved)
- {
- int entropy_count, orig, have_bytes;
- size_t ibytes, nfrac;
- BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
- /* Can we pull enough? */
- retry:
- entropy_count = orig = READ_ONCE(r->entropy_count);
- ibytes = nbytes;
- /* never pull more than available */
- have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
- if ((have_bytes -= reserved) < 0)
- have_bytes = 0;
- ibytes = min_t(size_t, ibytes, have_bytes);
- if (ibytes < min)
- ibytes = 0;
- if (WARN_ON(entropy_count < 0)) {
- pr_warn("negative entropy count: pool %s count %d\n",
- r->name, entropy_count);
- entropy_count = 0;
- }
- nfrac = ibytes << (ENTROPY_SHIFT + 3);
- if ((size_t) entropy_count > nfrac)
- entropy_count -= nfrac;
- else
- entropy_count = 0;
- if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
- goto retry;
- trace_debit_entropy(r->name, 8 * ibytes);
- if (ibytes && ENTROPY_BITS(r) < random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
- return ibytes;
- }
- /*
- * This function does the actual extraction for extract_entropy and
- * extract_entropy_user.
- *
- * Note: we assume that .poolwords is a multiple of 16 words.
- */
- static void extract_buf(struct entropy_store *r, __u8 *out)
- {
- int i;
- union {
- __u32 w[5];
- unsigned long l[LONGS(20)];
- } hash;
- __u32 workspace[SHA1_WORKSPACE_WORDS];
- unsigned long flags;
- /*
- * If we have an architectural hardware random number
- * generator, use it for SHA's initial vector
- */
- sha1_init(hash.w);
- for (i = 0; i < LONGS(20); i++) {
- unsigned long v;
- if (!arch_get_random_long(&v))
- break;
- hash.l[i] = v;
- }
- /* Generate a hash across the pool, 16 words (512 bits) at a time */
- spin_lock_irqsave(&r->lock, flags);
- for (i = 0; i < r->poolinfo->poolwords; i += 16)
- sha1_transform(hash.w, (__u8 *)(r->pool + i), workspace);
- /*
- * We mix the hash back into the pool to prevent backtracking
- * attacks (where the attacker knows the state of the pool
- * plus the current outputs, and attempts to find previous
- * ouputs), unless the hash function can be inverted. By
- * mixing at least a SHA1 worth of hash data back, we make
- * brute-forcing the feedback as hard as brute-forcing the
- * hash.
- */
- __mix_pool_bytes(r, hash.w, sizeof(hash.w));
- spin_unlock_irqrestore(&r->lock, flags);
- memzero_explicit(workspace, sizeof(workspace));
- /*
- * In case the hash function has some recognizable output
- * pattern, we fold it in half. Thus, we always feed back
- * twice as much data as we output.
- */
- hash.w[0] ^= hash.w[3];
- hash.w[1] ^= hash.w[4];
- hash.w[2] ^= rol32(hash.w[2], 16);
- memcpy(out, &hash, EXTRACT_SIZE);
- memzero_explicit(&hash, sizeof(hash));
- }
- static ssize_t _extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int fips)
- {
- ssize_t ret = 0, i;
- __u8 tmp[EXTRACT_SIZE];
- unsigned long flags;
- while (nbytes) {
- extract_buf(r, tmp);
- if (fips) {
- spin_lock_irqsave(&r->lock, flags);
- if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
- panic("Hardware RNG duplicated output!\n");
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- spin_unlock_irqrestore(&r->lock, flags);
- }
- i = min_t(int, nbytes, EXTRACT_SIZE);
- memcpy(buf, tmp, i);
- nbytes -= i;
- buf += i;
- ret += i;
- }
- /* Wipe data just returned from memory */
- memzero_explicit(tmp, sizeof(tmp));
- return ret;
- }
- /*
- * This function extracts randomness from the "entropy pool", and
- * returns it in a buffer.
- *
- * The min parameter specifies the minimum amount we can pull before
- * failing to avoid races that defeat catastrophic reseeding while the
- * reserved parameter indicates how much entropy we must leave in the
- * pool after each pull to avoid starving other readers.
- */
- static ssize_t extract_entropy(struct entropy_store *r, void *buf,
- size_t nbytes, int min, int reserved)
- {
- __u8 tmp[EXTRACT_SIZE];
- unsigned long flags;
- /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
- if (fips_enabled) {
- spin_lock_irqsave(&r->lock, flags);
- if (!r->last_data_init) {
- r->last_data_init = 1;
- spin_unlock_irqrestore(&r->lock, flags);
- trace_extract_entropy(r->name, EXTRACT_SIZE,
- ENTROPY_BITS(r), _RET_IP_);
- extract_buf(r, tmp);
- spin_lock_irqsave(&r->lock, flags);
- memcpy(r->last_data, tmp, EXTRACT_SIZE);
- }
- spin_unlock_irqrestore(&r->lock, flags);
- }
- trace_extract_entropy(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
- nbytes = account(r, nbytes, min, reserved);
- return _extract_entropy(r, buf, nbytes, fips_enabled);
- }
- #define warn_unseeded_randomness(previous) \
- _warn_unseeded_randomness(__func__, (void *) _RET_IP_, (previous))
- static void _warn_unseeded_randomness(const char *func_name, void *caller,
- void **previous)
- {
- #ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- const bool print_once = false;
- #else
- static bool print_once __read_mostly;
- #endif
- if (print_once ||
- crng_ready() ||
- (previous && (caller == READ_ONCE(*previous))))
- return;
- WRITE_ONCE(*previous, caller);
- #ifndef CONFIG_WARN_ALL_UNSEEDED_RANDOM
- print_once = true;
- #endif
- if (__ratelimit(&unseeded_warning))
- printk_deferred(KERN_NOTICE "random: %s called from %pS "
- "with crng_init=%d\n", func_name, caller,
- crng_init);
- }
- /*
- * This function is the exported kernel interface. It returns some
- * number of good random numbers, suitable for key generation, seeding
- * TCP sequence numbers, etc. It does not rely on the hardware random
- * number generator. For random bytes direct from the hardware RNG
- * (when available), use get_random_bytes_arch(). In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once
- * at any point prior.
- */
- static void _get_random_bytes(void *buf, int nbytes)
- {
- __u8 tmp[CHACHA_BLOCK_SIZE] __aligned(4);
- trace_get_random_bytes(nbytes, _RET_IP_);
- while (nbytes >= CHACHA_BLOCK_SIZE) {
- extract_crng(buf);
- buf += CHACHA_BLOCK_SIZE;
- nbytes -= CHACHA_BLOCK_SIZE;
- }
- if (nbytes > 0) {
- extract_crng(tmp);
- memcpy(buf, tmp, nbytes);
- crng_backtrack_protect(tmp, nbytes);
- } else
- crng_backtrack_protect(tmp, CHACHA_BLOCK_SIZE);
- memzero_explicit(tmp, sizeof(tmp));
- }
- void get_random_bytes(void *buf, int nbytes)
- {
- static void *previous;
- warn_unseeded_randomness(&previous);
- _get_random_bytes(buf, nbytes);
- }
- EXPORT_SYMBOL(get_random_bytes);
- /*
- * Each time the timer fires, we expect that we got an unpredictable
- * jump in the cycle counter. Even if the timer is running on another
- * CPU, the timer activity will be touching the stack of the CPU that is
- * generating entropy..
- *
- * Note that we don't re-arm the timer in the timer itself - we are
- * happy to be scheduled away, since that just makes the load more
- * complex, but we do not want the timer to keep ticking unless the
- * entropy loop is running.
- *
- * So the re-arming always happens in the entropy loop itself.
- */
- static void entropy_timer(struct timer_list *t)
- {
- credit_entropy_bits(&input_pool, 1);
- }
- /*
- * If we have an actual cycle counter, see if we can
- * generate enough entropy with timing noise
- */
- static void try_to_generate_entropy(void)
- {
- struct {
- unsigned long now;
- struct timer_list timer;
- } stack;
- stack.now = random_get_entropy();
- /* Slow counter - or none. Don't even bother */
- if (stack.now == random_get_entropy())
- return;
- timer_setup_on_stack(&stack.timer, entropy_timer, 0);
- while (!crng_ready()) {
- if (!timer_pending(&stack.timer))
- mod_timer(&stack.timer, jiffies+1);
- mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
- schedule();
- stack.now = random_get_entropy();
- }
- del_timer_sync(&stack.timer);
- destroy_timer_on_stack(&stack.timer);
- mix_pool_bytes(&input_pool, &stack.now, sizeof(stack.now));
- }
- /*
- * Wait for the urandom pool to be seeded and thus guaranteed to supply
- * cryptographically secure random numbers. This applies to: the /dev/urandom
- * device, the get_random_bytes function, and the get_random_{u32,u64,int,long}
- * family of functions. Using any of these functions without first calling
- * this function forfeits the guarantee of security.
- *
- * Returns: 0 if the urandom pool has been seeded.
- * -ERESTARTSYS if the function was interrupted by a signal.
- */
- int wait_for_random_bytes(void)
- {
- if (likely(crng_ready()))
- return 0;
- do {
- int ret;
- ret = wait_event_interruptible_timeout(crng_init_wait, crng_ready(), HZ);
- if (ret)
- return ret > 0 ? 0 : ret;
- try_to_generate_entropy();
- } while (!crng_ready());
- return 0;
- }
- EXPORT_SYMBOL(wait_for_random_bytes);
- /*
- * Returns whether or not the urandom pool has been seeded and thus guaranteed
- * to supply cryptographically secure random numbers. This applies to: the
- * /dev/urandom device, the get_random_bytes function, and the get_random_{u32,
- * ,u64,int,long} family of functions.
- *
- * Returns: true if the urandom pool has been seeded.
- * false if the urandom pool has not been seeded.
- */
- bool rng_is_initialized(void)
- {
- return crng_ready();
- }
- EXPORT_SYMBOL(rng_is_initialized);
- /*
- * Add a callback function that will be invoked when the nonblocking
- * pool is initialised.
- *
- * returns: 0 if callback is successfully added
- * -EALREADY if pool is already initialised (callback not called)
- * -ENOENT if module for callback is not alive
- */
- int add_random_ready_callback(struct random_ready_callback *rdy)
- {
- struct module *owner;
- unsigned long flags;
- int err = -EALREADY;
- if (crng_ready())
- return err;
- owner = rdy->owner;
- if (!try_module_get(owner))
- return -ENOENT;
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (crng_ready())
- goto out;
- owner = NULL;
- list_add(&rdy->list, &random_ready_list);
- err = 0;
- out:
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
- module_put(owner);
- return err;
- }
- EXPORT_SYMBOL(add_random_ready_callback);
- /*
- * Delete a previously registered readiness callback function.
- */
- void del_random_ready_callback(struct random_ready_callback *rdy)
- {
- unsigned long flags;
- struct module *owner = NULL;
- spin_lock_irqsave(&random_ready_list_lock, flags);
- if (!list_empty(&rdy->list)) {
- list_del_init(&rdy->list);
- owner = rdy->owner;
- }
- spin_unlock_irqrestore(&random_ready_list_lock, flags);
- module_put(owner);
- }
- EXPORT_SYMBOL(del_random_ready_callback);
- /*
- * This function will use the architecture-specific hardware random
- * number generator if it is available. The arch-specific hw RNG will
- * almost certainly be faster than what we can do in software, but it
- * is impossible to verify that it is implemented securely (as
- * opposed, to, say, the AES encryption of a sequence number using a
- * key known by the NSA). So it's useful if we need the speed, but
- * only if we're willing to trust the hardware manufacturer not to
- * have put in a back door.
- *
- * Return number of bytes filled in.
- */
- int __must_check get_random_bytes_arch(void *buf, int nbytes)
- {
- int left = nbytes;
- char *p = buf;
- trace_get_random_bytes_arch(left, _RET_IP_);
- while (left) {
- unsigned long v;
- int chunk = min_t(int, left, sizeof(unsigned long));
- if (!arch_get_random_long(&v))
- break;
- memcpy(p, &v, chunk);
- p += chunk;
- left -= chunk;
- }
- return nbytes - left;
- }
- EXPORT_SYMBOL(get_random_bytes_arch);
- /*
- * init_std_data - initialize pool with system data
- *
- * @r: pool to initialize
- *
- * This function clears the pool's entropy count and mixes some system
- * data into the pool to prepare it for use. The pool is not cleared
- * as that can only decrease the entropy in the pool.
- */
- static void __init init_std_data(struct entropy_store *r)
- {
- int i;
- ktime_t now = ktime_get_real();
- unsigned long rv;
- mix_pool_bytes(r, &now, sizeof(now));
- for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
- if (!arch_get_random_seed_long(&rv) &&
- !arch_get_random_long(&rv))
- rv = random_get_entropy();
- mix_pool_bytes(r, &rv, sizeof(rv));
- }
- mix_pool_bytes(r, utsname(), sizeof(*(utsname())));
- }
- /*
- * Note that setup_arch() may call add_device_randomness()
- * long before we get here. This allows seeding of the pools
- * with some platform dependent data very early in the boot
- * process. But it limits our options here. We must use
- * statically allocated structures that already have all
- * initializations complete at compile time. We should also
- * take care not to overwrite the precious per platform data
- * we were given.
- */
- int __init rand_initialize(void)
- {
- init_std_data(&input_pool);
- if (crng_need_final_init)
- crng_finalize_init(&primary_crng);
- crng_initialize_primary(&primary_crng);
- crng_global_init_time = jiffies;
- if (ratelimit_disable) {
- urandom_warning.interval = 0;
- unseeded_warning.interval = 0;
- }
- return 0;
- }
- #ifdef CONFIG_BLOCK
- void rand_initialize_disk(struct gendisk *disk)
- {
- struct timer_rand_state *state;
- /*
- * If kzalloc returns null, we just won't use that entropy
- * source.
- */
- state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL);
- if (state) {
- state->last_time = INITIAL_JIFFIES;
- disk->random = state;
- }
- }
- #endif
- static ssize_t
- urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes,
- loff_t *ppos)
- {
- int ret;
- nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
- ret = extract_crng_user(buf, nbytes);
- trace_urandom_read(8 * nbytes, 0, ENTROPY_BITS(&input_pool));
- return ret;
- }
- static ssize_t
- urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
- {
- unsigned long flags;
- static int maxwarn = 10;
- if (!crng_ready() && maxwarn > 0) {
- maxwarn--;
- if (__ratelimit(&urandom_warning))
- pr_notice("%s: uninitialized urandom read (%zd bytes read)\n",
- current->comm, nbytes);
- spin_lock_irqsave(&primary_crng.lock, flags);
- crng_init_cnt = 0;
- spin_unlock_irqrestore(&primary_crng.lock, flags);
- }
- return urandom_read_nowarn(file, buf, nbytes, ppos);
- }
- static ssize_t
- random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
- {
- int ret;
- ret = wait_for_random_bytes();
- if (ret != 0)
- return ret;
- return urandom_read_nowarn(file, buf, nbytes, ppos);
- }
- static __poll_t
- random_poll(struct file *file, poll_table * wait)
- {
- __poll_t mask;
- poll_wait(file, &crng_init_wait, wait);
- poll_wait(file, &random_write_wait, wait);
- mask = 0;
- if (crng_ready())
- mask |= EPOLLIN | EPOLLRDNORM;
- if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits)
- mask |= EPOLLOUT | EPOLLWRNORM;
- return mask;
- }
- static int
- write_pool(struct entropy_store *r, const char __user *buffer, size_t count)
- {
- size_t bytes;
- __u32 t, buf[16];
- const char __user *p = buffer;
- while (count > 0) {
- int b, i = 0;
- bytes = min(count, sizeof(buf));
- if (copy_from_user(&buf, p, bytes))
- return -EFAULT;
- for (b = bytes ; b > 0 ; b -= sizeof(__u32), i++) {
- if (!arch_get_random_int(&t))
- break;
- buf[i] ^= t;
- }
- count -= bytes;
- p += bytes;
- mix_pool_bytes(r, buf, bytes);
- cond_resched();
- }
- return 0;
- }
- static ssize_t random_write(struct file *file, const char __user *buffer,
- size_t count, loff_t *ppos)
- {
- size_t ret;
- ret = write_pool(&input_pool, buffer, count);
- if (ret)
- return ret;
- return (ssize_t)count;
- }
- static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
- {
- int size, ent_count;
- int __user *p = (int __user *)arg;
- int retval;
- switch (cmd) {
- case RNDGETENTCNT:
- /* inherently racy, no point locking */
- ent_count = ENTROPY_BITS(&input_pool);
- if (put_user(ent_count, p))
- return -EFAULT;
- return 0;
- case RNDADDTOENTCNT:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (get_user(ent_count, p))
- return -EFAULT;
- return credit_entropy_bits_safe(&input_pool, ent_count);
- case RNDADDENTROPY:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (get_user(ent_count, p++))
- return -EFAULT;
- if (ent_count < 0)
- return -EINVAL;
- if (get_user(size, p++))
- return -EFAULT;
- retval = write_pool(&input_pool, (const char __user *)p,
- size);
- if (retval < 0)
- return retval;
- return credit_entropy_bits_safe(&input_pool, ent_count);
- case RNDZAPENTCNT:
- case RNDCLEARPOOL:
- /*
- * Clear the entropy pool counters. We no longer clear
- * the entropy pool, as that's silly.
- */
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) {
- wake_up_interruptible(&random_write_wait);
- kill_fasync(&fasync, SIGIO, POLL_OUT);
- }
- return 0;
- case RNDRESEEDCRNG:
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (crng_init < 2)
- return -ENODATA;
- crng_reseed(&primary_crng, &input_pool);
- WRITE_ONCE(crng_global_init_time, jiffies - 1);
- return 0;
- default:
- return -EINVAL;
- }
- }
- static int random_fasync(int fd, struct file *filp, int on)
- {
- return fasync_helper(fd, filp, on, &fasync);
- }
- const struct file_operations random_fops = {
- .read = random_read,
- .write = random_write,
- .poll = random_poll,
- .unlocked_ioctl = random_ioctl,
- .compat_ioctl = compat_ptr_ioctl,
- .fasync = random_fasync,
- .llseek = noop_llseek,
- };
- const struct file_operations urandom_fops = {
- .read = urandom_read,
- .write = random_write,
- .unlocked_ioctl = random_ioctl,
- .compat_ioctl = compat_ptr_ioctl,
- .fasync = random_fasync,
- .llseek = noop_llseek,
- };
- SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
- unsigned int, flags)
- {
- int ret;
- if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE))
- return -EINVAL;
- /*
- * Requesting insecure and blocking randomness at the same time makes
- * no sense.
- */
- if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
- return -EINVAL;
- if (count > INT_MAX)
- count = INT_MAX;
- if (!(flags & GRND_INSECURE) && !crng_ready()) {
- if (flags & GRND_NONBLOCK)
- return -EAGAIN;
- ret = wait_for_random_bytes();
- if (unlikely(ret))
- return ret;
- }
- return urandom_read_nowarn(NULL, buf, count, NULL);
- }
- /********************************************************************
- *
- * Sysctl interface
- *
- ********************************************************************/
- #ifdef CONFIG_SYSCTL
- #include <linux/sysctl.h>
- static int min_write_thresh;
- static int max_write_thresh = INPUT_POOL_WORDS * 32;
- static int random_min_urandom_seed = 60;
- static char sysctl_bootid[16];
- /*
- * This function is used to return both the bootid UUID, and random
- * UUID. The difference is in whether table->data is NULL; if it is,
- * then a new UUID is generated and returned to the user.
- *
- * If the user accesses this via the proc interface, the UUID will be
- * returned as an ASCII string in the standard UUID format; if via the
- * sysctl system call, as 16 bytes of binary data.
- */
- static int proc_do_uuid(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
- {
- struct ctl_table fake_table;
- unsigned char buf[64], tmp_uuid[16], *uuid;
- uuid = table->data;
- if (!uuid) {
- uuid = tmp_uuid;
- generate_random_uuid(uuid);
- } else {
- static DEFINE_SPINLOCK(bootid_spinlock);
- spin_lock(&bootid_spinlock);
- if (!uuid[8])
- generate_random_uuid(uuid);
- spin_unlock(&bootid_spinlock);
- }
- sprintf(buf, "%pU", uuid);
- fake_table.data = buf;
- fake_table.maxlen = sizeof(buf);
- return proc_dostring(&fake_table, write, buffer, lenp, ppos);
- }
- /*
- * Return entropy available scaled to integral bits
- */
- static int proc_do_entropy(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos)
- {
- struct ctl_table fake_table;
- int entropy_count;
- entropy_count = *(int *)table->data >> ENTROPY_SHIFT;
- fake_table.data = &entropy_count;
- fake_table.maxlen = sizeof(entropy_count);
- return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
- }
- static int sysctl_poolsize = INPUT_POOL_WORDS * 32;
- extern struct ctl_table random_table[];
- struct ctl_table random_table[] = {
- {
- .procname = "poolsize",
- .data = &sysctl_poolsize,
- .maxlen = sizeof(int),
- .mode = 0444,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "entropy_avail",
- .maxlen = sizeof(int),
- .mode = 0444,
- .proc_handler = proc_do_entropy,
- .data = &input_pool.entropy_count,
- },
- {
- .procname = "write_wakeup_threshold",
- .data = &random_write_wakeup_bits,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &min_write_thresh,
- .extra2 = &max_write_thresh,
- },
- {
- .procname = "urandom_min_reseed_secs",
- .data = &random_min_urandom_seed,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "boot_id",
- .data = &sysctl_bootid,
- .maxlen = 16,
- .mode = 0444,
- .proc_handler = proc_do_uuid,
- },
- {
- .procname = "uuid",
- .maxlen = 16,
- .mode = 0444,
- .proc_handler = proc_do_uuid,
- },
- #ifdef ADD_INTERRUPT_BENCH
- {
- .procname = "add_interrupt_avg_cycles",
- .data = &avg_cycles,
- .maxlen = sizeof(avg_cycles),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
- {
- .procname = "add_interrupt_avg_deviation",
- .data = &avg_deviation,
- .maxlen = sizeof(avg_deviation),
- .mode = 0444,
- .proc_handler = proc_doulongvec_minmax,
- },
- #endif
- { }
- };
- #endif /* CONFIG_SYSCTL */
- struct batched_entropy {
- union {
- u64 entropy_u64[CHACHA_BLOCK_SIZE / sizeof(u64)];
- u32 entropy_u32[CHACHA_BLOCK_SIZE / sizeof(u32)];
- };
- unsigned int position;
- spinlock_t batch_lock;
- };
- /*
- * Get a random word for internal kernel use only. The quality of the random
- * number is good as /dev/urandom, but there is no backtrack protection, with
- * the goal of being quite fast and not depleting entropy. In order to ensure
- * that the randomness provided by this function is okay, the function
- * wait_for_random_bytes() should be called and return 0 at least once at any
- * point prior.
- */
- static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock),
- };
- u64 get_random_u64(void)
- {
- u64 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
- warn_unseeded_randomness(&previous);
- batch = raw_cpu_ptr(&batched_entropy_u64);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
- extract_crng((u8 *)batch->entropy_u64);
- batch->position = 0;
- }
- ret = batch->entropy_u64[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
- return ret;
- }
- EXPORT_SYMBOL(get_random_u64);
- static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
- .batch_lock = __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock),
- };
- u32 get_random_u32(void)
- {
- u32 ret;
- unsigned long flags;
- struct batched_entropy *batch;
- static void *previous;
- warn_unseeded_randomness(&previous);
- batch = raw_cpu_ptr(&batched_entropy_u32);
- spin_lock_irqsave(&batch->batch_lock, flags);
- if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
- extract_crng((u8 *)batch->entropy_u32);
- batch->position = 0;
- }
- ret = batch->entropy_u32[batch->position++];
- spin_unlock_irqrestore(&batch->batch_lock, flags);
- return ret;
- }
- EXPORT_SYMBOL(get_random_u32);
- /* It's important to invalidate all potential batched entropy that might
- * be stored before the crng is initialized, which we can do lazily by
- * simply resetting the counter to zero so that it's re-extracted on the
- * next usage. */
- static void invalidate_batched_entropy(void)
- {
- int cpu;
- unsigned long flags;
- for_each_possible_cpu (cpu) {
- struct batched_entropy *batched_entropy;
- batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu);
- spin_lock_irqsave(&batched_entropy->batch_lock, flags);
- batched_entropy->position = 0;
- spin_unlock(&batched_entropy->batch_lock);
- batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu);
- spin_lock(&batched_entropy->batch_lock);
- batched_entropy->position = 0;
- spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
- }
- }
- /**
- * randomize_page - Generate a random, page aligned address
- * @start: The smallest acceptable address the caller will take.
- * @range: The size of the area, starting at @start, within which the
- * random address must fall.
- *
- * If @start + @range would overflow, @range is capped.
- *
- * NOTE: Historical use of randomize_range, which this replaces, presumed that
- * @start was already page aligned. We now align it regardless.
- *
- * Return: A page aligned address within [start, start + range). On error,
- * @start is returned.
- */
- unsigned long
- randomize_page(unsigned long start, unsigned long range)
- {
- if (!PAGE_ALIGNED(start)) {
- range -= PAGE_ALIGN(start) - start;
- start = PAGE_ALIGN(start);
- }
- if (start > ULONG_MAX - range)
- range = ULONG_MAX - start;
- range >>= PAGE_SHIFT;
- if (range == 0)
- return start;
- return start + (get_random_long() % range << PAGE_SHIFT);
- }
- /* Interface for in-kernel drivers of true hardware RNGs.
- * Those devices may produce endless random bits and will be throttled
- * when our pool is full.
- */
- void add_hwgenerator_randomness(const char *buffer, size_t count,
- size_t entropy)
- {
- struct entropy_store *poolp = &input_pool;
- if (unlikely(crng_init == 0)) {
- size_t ret = crng_fast_load(buffer, count);
- count -= ret;
- buffer += ret;
- if (!count || crng_init == 0)
- return;
- }
- /* Suspend writing if we're above the trickle threshold.
- * We'll be woken up again once below random_write_wakeup_thresh,
- * or when the calling thread is about to terminate.
- */
- wait_event_interruptible(random_write_wait,
- !system_wq || kthread_should_stop() ||
- ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
- mix_pool_bytes(poolp, buffer, count);
- credit_entropy_bits(poolp, entropy);
- }
- EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
- /* Handle random seed passed by bootloader.
- * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
- * it would be regarded as device data.
- * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
- */
- void add_bootloader_randomness(const void *buf, unsigned int size)
- {
- if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
- add_hwgenerator_randomness(buf, size, size * 8);
- else
- add_device_randomness(buf, size);
- }
- EXPORT_SYMBOL_GPL(add_bootloader_randomness);
|