Change get_random_{int,log} to use the CRNG used by /dev/urandom and
getrandom(2). It's faster and arguably more secure than cut-down MD5
that we had been using.
Also do some code cleanup.
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Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random
Pull random updates from Ted Ts'o:
"Change get_random_{int,log} to use the CRNG used by /dev/urandom and
getrandom(2). It's faster and arguably more secure than cut-down MD5
that we had been using.
Also do some code cleanup"
* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
random: move random_min_urandom_seed into CONFIG_SYSCTL ifdef block
random: convert get_random_int/long into get_random_u32/u64
random: use chacha20 for get_random_int/long
random: fix comment for unused random_min_urandom_seed
random: remove variable limit
random: remove stale urandom_init_wait
random: remove stale maybe_reseed_primary_crng
zero-colors
Linus Torvalds
commit
84c37c168c
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@ -312,13 +312,6 @@ static int random_read_wakeup_bits = 64;
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*/
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static int random_write_wakeup_bits = 28 * OUTPUT_POOL_WORDS;
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/*
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* The minimum number of seconds between urandom pool reseeding. We
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* do this to limit the amount of entropy that can be drained from the
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* input pool even if there are heavy demands on /dev/urandom.
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*/
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static int random_min_urandom_seed = 60;
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/*
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* Originally, we used a primitive polynomial of degree .poolwords
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* over GF(2). The taps for various sizes are defined below. They
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@ -409,7 +402,6 @@ static struct poolinfo {
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*/
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static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
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static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
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static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
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static struct fasync_struct *fasync;
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static DEFINE_SPINLOCK(random_ready_list_lock);
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@ -467,7 +459,6 @@ struct entropy_store {
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int entropy_count;
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int entropy_total;
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unsigned int initialized:1;
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unsigned int limit:1;
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unsigned int last_data_init:1;
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__u8 last_data[EXTRACT_SIZE];
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};
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@ -485,7 +476,6 @@ static __u32 blocking_pool_data[OUTPUT_POOL_WORDS] __latent_entropy;
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static struct entropy_store input_pool = {
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.poolinfo = &poolinfo_table[0],
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.name = "input",
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.limit = 1,
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.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
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.pool = input_pool_data
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};
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@ -493,7 +483,6 @@ static struct entropy_store input_pool = {
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static struct entropy_store blocking_pool = {
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.poolinfo = &poolinfo_table[1],
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.name = "blocking",
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.limit = 1,
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.pull = &input_pool,
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.lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock),
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.pool = blocking_pool_data,
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@ -855,13 +844,6 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r)
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spin_unlock_irqrestore(&primary_crng.lock, flags);
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}
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static inline void maybe_reseed_primary_crng(void)
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{
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if (crng_init > 2 &&
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time_after(jiffies, primary_crng.init_time + CRNG_RESEED_INTERVAL))
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crng_reseed(&primary_crng, &input_pool);
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}
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static inline void crng_wait_ready(void)
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{
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wait_event_interruptible(crng_init_wait, crng_ready());
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@ -1220,15 +1202,6 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
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r->entropy_count > r->poolinfo->poolfracbits)
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return;
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if (r->limit == 0 && random_min_urandom_seed) {
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unsigned long now = jiffies;
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if (time_before(now,
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r->last_pulled + random_min_urandom_seed * HZ))
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return;
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r->last_pulled = now;
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}
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_xfer_secondary_pool(r, nbytes);
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}
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@ -1236,8 +1209,6 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
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{
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__u32 tmp[OUTPUT_POOL_WORDS];
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/* For /dev/random's pool, always leave two wakeups' worth */
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int rsvd_bytes = r->limit ? 0 : random_read_wakeup_bits / 4;
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int bytes = nbytes;
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/* pull at least as much as a wakeup */
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@ -1248,7 +1219,7 @@ static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
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trace_xfer_secondary_pool(r->name, bytes * 8, nbytes * 8,
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ENTROPY_BITS(r), ENTROPY_BITS(r->pull));
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bytes = extract_entropy(r->pull, tmp, bytes,
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random_read_wakeup_bits / 8, rsvd_bytes);
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random_read_wakeup_bits / 8, 0);
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mix_pool_bytes(r, tmp, bytes);
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credit_entropy_bits(r, bytes*8);
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}
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@ -1276,7 +1247,7 @@ static void push_to_pool(struct work_struct *work)
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static size_t account(struct entropy_store *r, size_t nbytes, int min,
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int reserved)
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{
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int entropy_count, orig;
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int entropy_count, orig, have_bytes;
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size_t ibytes, nfrac;
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BUG_ON(r->entropy_count > r->poolinfo->poolfracbits);
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@ -1285,14 +1256,12 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
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retry:
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entropy_count = orig = ACCESS_ONCE(r->entropy_count);
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ibytes = nbytes;
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/* If limited, never pull more than available */
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if (r->limit) {
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int have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
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/* never pull more than available */
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have_bytes = entropy_count >> (ENTROPY_SHIFT + 3);
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if ((have_bytes -= reserved) < 0)
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have_bytes = 0;
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ibytes = min_t(size_t, ibytes, have_bytes);
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}
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if ((have_bytes -= reserved) < 0)
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have_bytes = 0;
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ibytes = min_t(size_t, ibytes, have_bytes);
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if (ibytes < min)
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ibytes = 0;
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@ -1912,6 +1881,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
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static int min_read_thresh = 8, min_write_thresh;
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static int max_read_thresh = OUTPUT_POOL_WORDS * 32;
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static int max_write_thresh = INPUT_POOL_WORDS * 32;
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static int random_min_urandom_seed = 60;
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static char sysctl_bootid[16];
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/*
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@ -2042,63 +2012,64 @@ struct ctl_table random_table[] = {
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};
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#endif /* CONFIG_SYSCTL */
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static u32 random_int_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
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int random_int_secret_init(void)
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{
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get_random_bytes(random_int_secret, sizeof(random_int_secret));
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return 0;
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}
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static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash)
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__aligned(sizeof(unsigned long));
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struct batched_entropy {
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union {
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u64 entropy_u64[CHACHA20_BLOCK_SIZE / sizeof(u64)];
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u32 entropy_u32[CHACHA20_BLOCK_SIZE / sizeof(u32)];
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};
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unsigned int position;
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};
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/*
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* Get a random word for internal kernel use only. Similar to urandom but
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* with the goal of minimal entropy pool depletion. As a result, the random
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* value is not cryptographically secure but for several uses the cost of
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* depleting entropy is too high
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* Get a random word for internal kernel use only. The quality of the random
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* number is either as good as RDRAND or as good as /dev/urandom, with the
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* goal of being quite fast and not depleting entropy.
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*/
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unsigned int get_random_int(void)
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static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64);
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u64 get_random_u64(void)
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{
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__u32 *hash;
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unsigned int ret;
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u64 ret;
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struct batched_entropy *batch;
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#if BITS_PER_LONG == 64
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if (arch_get_random_long((unsigned long *)&ret))
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return ret;
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#else
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if (arch_get_random_long((unsigned long *)&ret) &&
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arch_get_random_long((unsigned long *)&ret + 1))
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return ret;
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#endif
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batch = &get_cpu_var(batched_entropy_u64);
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if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
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extract_crng((u8 *)batch->entropy_u64);
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batch->position = 0;
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}
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ret = batch->entropy_u64[batch->position++];
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put_cpu_var(batched_entropy_u64);
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return ret;
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}
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EXPORT_SYMBOL(get_random_u64);
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static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32);
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u32 get_random_u32(void)
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{
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u32 ret;
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struct batched_entropy *batch;
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if (arch_get_random_int(&ret))
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return ret;
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hash = get_cpu_var(get_random_int_hash);
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hash[0] += current->pid + jiffies + random_get_entropy();
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md5_transform(hash, random_int_secret);
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ret = hash[0];
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put_cpu_var(get_random_int_hash);
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batch = &get_cpu_var(batched_entropy_u32);
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if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
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extract_crng((u8 *)batch->entropy_u32);
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batch->position = 0;
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}
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ret = batch->entropy_u32[batch->position++];
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put_cpu_var(batched_entropy_u32);
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return ret;
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}
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EXPORT_SYMBOL(get_random_int);
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/*
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* Same as get_random_int(), but returns unsigned long.
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*/
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unsigned long get_random_long(void)
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{
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__u32 *hash;
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unsigned long ret;
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if (arch_get_random_long(&ret))
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return ret;
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hash = get_cpu_var(get_random_int_hash);
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hash[0] += current->pid + jiffies + random_get_entropy();
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md5_transform(hash, random_int_secret);
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ret = *(unsigned long *)hash;
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put_cpu_var(get_random_int_hash);
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return ret;
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}
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EXPORT_SYMBOL(get_random_long);
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EXPORT_SYMBOL(get_random_u32);
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/**
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* randomize_page - Generate a random, page aligned address
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@ -37,14 +37,26 @@ extern void get_random_bytes(void *buf, int nbytes);
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extern int add_random_ready_callback(struct random_ready_callback *rdy);
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extern void del_random_ready_callback(struct random_ready_callback *rdy);
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extern void get_random_bytes_arch(void *buf, int nbytes);
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extern int random_int_secret_init(void);
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#ifndef MODULE
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extern const struct file_operations random_fops, urandom_fops;
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#endif
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unsigned int get_random_int(void);
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unsigned long get_random_long(void);
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u32 get_random_u32(void);
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u64 get_random_u64(void);
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static inline unsigned int get_random_int(void)
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{
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return get_random_u32();
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}
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static inline unsigned long get_random_long(void)
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{
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#if BITS_PER_LONG == 64
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return get_random_u64();
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#else
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return get_random_u32();
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#endif
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}
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unsigned long randomize_page(unsigned long start, unsigned long range);
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u32 prandom_u32(void);
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@ -882,7 +882,6 @@ static void __init do_basic_setup(void)
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do_ctors();
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usermodehelper_enable();
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do_initcalls();
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random_int_secret_init();
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}
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static void __init do_pre_smp_initcalls(void)
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Loading…
Reference in New Issue