mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
2316 lines
67 KiB
2316 lines
67 KiB
/* |
|
* random.c -- A strong random number generator |
|
* |
|
* Copyright (C) 2017 Jason A. Donenfeld <[email protected]>. All |
|
* Rights Reserved. |
|
* |
|
* Copyright Matt Mackall <[email protected]>, 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/sha1.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; |
|
#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; |
|
} |
|
|
|
#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; |
|
} |
|
mb(); |
|
if (cmpxchg(&crng_node_pool, NULL, pool)) { |
|
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); |
|
} |
|
#else |
|
static void numa_crng_init(void) {} |
|
#endif |
|
|
|
/* |
|
* crng_fast_load() can be called by code in the interrupt service |
|
* path. So we can't afford to dilly-dally. |
|
*/ |
|
static int crng_fast_load(const char *cp, size_t len) |
|
{ |
|
unsigned long flags; |
|
char *p; |
|
|
|
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--; |
|
} |
|
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 1; |
|
} |
|
|
|
/* |
|
* 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)); |
|
crng->init_time = jiffies; |
|
spin_unlock_irqrestore(&crng->lock, flags); |
|
if (crng == &primary_crng && crng_init < 2) { |
|
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; |
|
} |
|
} |
|
} |
|
|
|
static void _extract_crng(struct crng_state *crng, |
|
__u8 out[CHACHA_BLOCK_SIZE]) |
|
{ |
|
unsigned long v, flags; |
|
|
|
if (crng_ready() && |
|
(time_after(crng_global_init_time, crng->init_time) || |
|
time_after(jiffies, crng->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]) |
|
{ |
|
struct crng_state *crng = NULL; |
|
|
|
#ifdef CONFIG_NUMA |
|
if (crng_node_pool) |
|
crng = crng_node_pool[numa_node_id()]; |
|
if (crng == NULL) |
|
#endif |
|
crng = &primary_crng; |
|
_extract_crng(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) |
|
{ |
|
struct crng_state *crng = NULL; |
|
|
|
#ifdef CONFIG_NUMA |
|
if (crng_node_pool) |
|
crng = crng_node_pool[numa_node_id()]; |
|
if (crng == NULL) |
|
#endif |
|
crng = &primary_crng; |
|
_crng_backtrack_protect(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; |
|
|
|
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))) { |
|
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)); |
|
spin_unlock(&r->lock); |
|
|
|
fast_pool->count = 0; |
|
|
|
/* award one bit for the contents of the fast pool */ |
|
credit_entropy_bits(r, 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); |
|
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; |
|
input_pool.entropy_count = 0; |
|
return 0; |
|
case RNDRESEEDCRNG: |
|
if (!capable(CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
if (crng_init < 2) |
|
return -ENODATA; |
|
crng_reseed(&primary_crng, &input_pool); |
|
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)) { |
|
crng_fast_load(buffer, count); |
|
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, 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);
|
|
|