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Donenfeld" To: Jens Axboe , LKML Cc: "Jason A . Donenfeld" Subject: [PATCH v3 2/3] random: convert to using fops->write_iter() Date: Fri, 20 May 2022 02:40:57 +0200 Message-Id: <20220520004058.96691-3-Jason@zx2c4.com> In-Reply-To: <20220520004058.96691-1-Jason@zx2c4.com> References: <20220520004058.96691-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jens Axboe 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 [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 --- 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