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Date: Fri, 20 May 2022 02:40:57 +0200
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: Jens Axboe <axboe@...nel.dk>, LKML <linux-kernel@...r.kernel.org>
Cc: "Jason A . Donenfeld" <Jason@...c4.com>
Subject: [PATCH v3 2/3] random: convert to using fops->write_iter()
From: Jens Axboe <axboe@...nel.dk>
Now that the read side has been converted to fix a regression with
splice, convert the write side as well to have some symmetry in the
interface used (and help deprecate ->write()).
Signed-off-by: Jens Axboe <axboe@...nel.dk>
[Jason: cleaned up random_ioctl a bit, require full writes in
RNDADDENTROPY since it's crediting entropy, and minimize control flow of
write_pool().]
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
drivers/char/random.c | 68 +++++++++++++++++++++++--------------------
1 file changed, 36 insertions(+), 32 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 2b2c3681f172..a664e2b89ae0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1278,39 +1278,32 @@ static __poll_t random_poll(struct file *file, poll_table *wait)
return crng_ready() ? EPOLLIN | EPOLLRDNORM : EPOLLOUT | EPOLLWRNORM;
}
-static int write_pool(const char __user *ubuf, size_t len)
+static ssize_t write_pool(struct iov_iter *from)
{
- size_t block_len;
- int ret = 0;
u8 block[BLAKE2S_BLOCK_SIZE];
+ ssize_t ret = 0;
- while (len) {
- block_len = min(len, sizeof(block));
- if (copy_from_user(block, ubuf, block_len)) {
- ret = -EFAULT;
- goto out;
- }
- len -= block_len;
- ubuf += block_len;
- mix_pool_bytes(block, block_len);
+ if (!iov_iter_count(from))
+ return 0;
+
+ for (;;) {
+ size_t copied, block_len = min(iov_iter_count(from), sizeof(block));
+
+ copied = copy_from_iter(block, block_len, from);
+ ret += copied;
+ mix_pool_bytes(block, copied);
+ if (!iov_iter_count(from) || copied != block_len)
+ break;
cond_resched();
}
-out:
memzero_explicit(block, sizeof(block));
- return ret;
+ return ret ? ret : -EFAULT;
}
-static ssize_t random_write(struct file *file, const char __user *ubuf,
- size_t len, loff_t *ppos)
+static ssize_t random_write_iter(struct kiocb *kiocb, struct iov_iter *from)
{
- int ret;
-
- ret = write_pool(ubuf, len);
- if (ret)
- return ret;
-
- return (ssize_t)len;
+ return write_pool(from);
}
static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *to)
@@ -1349,9 +1342,8 @@ static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *to)
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;
+ int ent_count;
switch (cmd) {
case RNDGETENTCNT:
@@ -1368,20 +1360,32 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
return -EINVAL;
credit_init_bits(ent_count);
return 0;
- case RNDADDENTROPY:
+ case RNDADDENTROPY: {
+ struct iov_iter iter;
+ struct iovec iov;
+ ssize_t ret;
+ int len;
+
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++))
+ if (get_user(len, p++))
+ return -EFAULT;
+
+ iov.iov_base = p;
+ iov.iov_len = len;
+ iov_iter_init(&iter, WRITE, &iov, 1, len);
+ ret = write_pool(&iter);
+ if (ret < 0)
+ return ret;
+ if (ret != len)
return -EFAULT;
- retval = write_pool((const char __user *)p, size);
- if (retval < 0)
- return retval;
credit_init_bits(ent_count);
return 0;
+ }
case RNDZAPENTCNT:
case RNDCLEARPOOL:
/* No longer has any effect. */
@@ -1407,7 +1411,7 @@ static int random_fasync(int fd, struct file *filp, int on)
const struct file_operations random_fops = {
.read_iter = random_read_iter,
- .write = random_write,
+ .write_iter = random_write_iter,
.poll = random_poll,
.unlocked_ioctl = random_ioctl,
.compat_ioctl = compat_ptr_ioctl,
@@ -1417,7 +1421,7 @@ const struct file_operations random_fops = {
const struct file_operations urandom_fops = {
.read_iter = urandom_read_iter,
- .write = random_write,
+ .write_iter = random_write_iter,
.unlocked_ioctl = random_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.fasync = random_fasync,
--
2.35.1
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