From 30c08efec8884fb106b8e57094baa51bb4c44e32 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 23 Dec 2019 00:20:48 -0800 Subject: random: make /dev/random be almost like /dev/urandom This patch changes the read semantics of /dev/random to be the same as /dev/urandom except that reads will block until the CRNG is ready. None of the cleanups that this enables have been done yet. As a result, this gives a warning about an unused function. Signed-off-by: Andy Lutomirski Link: https://lore.kernel.org/r/5e6ac8831c6cf2e56a7a4b39616d1732b2bdd06c.1577088521.git.luto@kernel.org Signed-off-by: Theodore Ts'o --- drivers/char/random.c | 55 +++++++++++++-------------------------------------- 1 file changed, 14 insertions(+), 41 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/random.c b/drivers/char/random.c index a92dfea038ce..0817d4af841e 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -354,7 +354,6 @@ #define INPUT_POOL_WORDS (1 << (INPUT_POOL_SHIFT-5)) #define OUTPUT_POOL_SHIFT 10 #define OUTPUT_POOL_WORDS (1 << (OUTPUT_POOL_SHIFT-5)) -#define SEC_XFER_SIZE 512 #define EXTRACT_SIZE 10 @@ -803,7 +802,6 @@ retry: if (entropy_bits >= random_read_wakeup_bits && wq_has_sleeper(&random_read_wait)) { wake_up_interruptible(&random_read_wait); - kill_fasync(&fasync, SIGIO, POLL_IN); } /* If the input pool is getting full, and the blocking * pool has room, send some entropy to the blocking @@ -1031,6 +1029,7 @@ static void crng_reseed(struct crng_state *crng, struct entropy_store *r) crng_init = 2; process_random_ready_list(); wake_up_interruptible(&crng_init_wait); + kill_fasync(&fasync, SIGIO, POLL_IN); pr_notice("random: crng init done\n"); if (unseeded_warning.missed) { pr_notice("random: %d get_random_xx warning(s) missed " @@ -1982,43 +1981,6 @@ void rand_initialize_disk(struct gendisk *disk) } #endif -static ssize_t -_random_read(int nonblock, char __user *buf, size_t nbytes) -{ - ssize_t n; - - if (nbytes == 0) - return 0; - - nbytes = min_t(size_t, nbytes, SEC_XFER_SIZE); - while (1) { - n = extract_entropy_user(&blocking_pool, buf, nbytes); - if (n < 0) - return n; - trace_random_read(n*8, (nbytes-n)*8, - ENTROPY_BITS(&blocking_pool), - ENTROPY_BITS(&input_pool)); - if (n > 0) - return n; - - /* Pool is (near) empty. Maybe wait and retry. */ - if (nonblock) - return -EAGAIN; - - wait_event_interruptible(random_read_wait, - blocking_pool.initialized && - (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits)); - if (signal_pending(current)) - return -ERESTARTSYS; - } -} - -static ssize_t -random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) -{ - return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes); -} - static ssize_t urandom_read_nowarn(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) @@ -2051,15 +2013,26 @@ urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 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, &random_read_wait, wait); + poll_wait(file, &crng_init_wait, wait); poll_wait(file, &random_write_wait, wait); mask = 0; - if (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits) + if (crng_ready()) mask |= EPOLLIN | EPOLLRDNORM; if (ENTROPY_BITS(&input_pool) < random_write_wakeup_bits) mask |= EPOLLOUT | EPOLLWRNORM; -- cgit