From c65f0221b72173c19398884f3f49ef775e2c668f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 19 May 2022 14:55:37 -0600 Subject: [PATCH 1/2] random: convert to using fops->read_iter() This is a pre-requisite to writing up splice() again for the random and urandom drivers. Signed-off-by: Jens Axboe --- drivers/char/random.c | 39 +++++++++++++++++++-------------------- 1 file changed, 19 insertions(+), 20 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 0958fa91a964..147921d471d8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -397,11 +397,12 @@ void get_random_bytes(void *buf, size_t len) } EXPORT_SYMBOL(get_random_bytes); -static ssize_t get_random_bytes_user(void __user *ubuf, size_t len) +static ssize_t get_random_bytes_user(struct iov_iter *to) { - size_t block_len, left, ret = 0; + size_t block_len, ret = 0; u32 chacha_state[CHACHA_STATE_WORDS]; u8 output[CHACHA_BLOCK_SIZE]; + size_t len = iov_iter_count(to); if (!len) return 0; @@ -418,7 +419,7 @@ static ssize_t get_random_bytes_user(void __user *ubuf, size_t len) * the user directly. */ if (len <= CHACHA_KEY_SIZE) { - ret = len - copy_to_user(ubuf, &chacha_state[4], len); + ret = copy_to_iter(&chacha_state[4], len, to); goto out_zero_chacha; } @@ -428,17 +429,12 @@ static ssize_t get_random_bytes_user(void __user *ubuf, size_t len) ++chacha_state[13]; block_len = min_t(size_t, len, CHACHA_BLOCK_SIZE); - left = copy_to_user(ubuf, output, block_len); - if (left) { - ret += block_len - left; + block_len = copy_to_iter(output, block_len, to); + if (!block_len) break; - } - ubuf += block_len; ret += block_len; len -= block_len; - if (!len) - break; BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0); if (ret % PAGE_SIZE == 0) { @@ -1248,6 +1244,9 @@ static void __cold try_to_generate_entropy(void) SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags) { + struct iovec iov = { .iov_base = ubuf }; + struct iov_iter iter; + if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) return -EINVAL; @@ -1270,7 +1269,9 @@ SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags if (unlikely(ret)) return ret; } - return get_random_bytes_user(ubuf, len); + iov.iov_len = len; + iov_iter_init(&iter, READ, &iov, 1, len); + return get_random_bytes_user(&iter); } static __poll_t random_poll(struct file *file, poll_table *wait) @@ -1314,8 +1315,7 @@ static ssize_t random_write(struct file *file, const char __user *ubuf, return (ssize_t)len; } -static ssize_t urandom_read(struct file *file, char __user *ubuf, - size_t len, loff_t *ppos) +static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *to) { static int maxwarn = 10; @@ -1332,22 +1332,21 @@ static ssize_t urandom_read(struct file *file, char __user *ubuf, else if (ratelimit_disable || __ratelimit(&urandom_warning)) { --maxwarn; pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", - current->comm, len); + current->comm, iov_iter_count(to)); } } - return get_random_bytes_user(ubuf, len); + return get_random_bytes_user(to); } -static ssize_t random_read(struct file *file, char __user *ubuf, - size_t len, loff_t *ppos) +static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *to) { int ret; ret = wait_for_random_bytes(); if (ret != 0) return ret; - return get_random_bytes_user(ubuf, len); + return get_random_bytes_user(to); } static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) @@ -1409,7 +1408,7 @@ static int random_fasync(int fd, struct file *filp, int on) } const struct file_operations random_fops = { - .read = random_read, + .read_iter = random_read_iter, .write = random_write, .poll = random_poll, .unlocked_ioctl = random_ioctl, @@ -1419,7 +1418,7 @@ const struct file_operations random_fops = { }; const struct file_operations urandom_fops = { - .read = urandom_read, + .read_iter = urandom_read_iter, .write = random_write, .unlocked_ioctl = random_ioctl, .compat_ioctl = compat_ptr_ioctl, -- 2.35.1