printk: Don't allow userspace to write to /dev/kmsg

There is extensive spam in dmesg because of userspace. This kills all "init", "healthd", "logd" messages in kernel logs and makes them more readable. Extracted from kerneltoast/android_kernel_google_wahoo@59f163a. Signed-off-by: idkwhoiam322 <[email protected]> Signed-off-by: prorooter007 <[email protected]> Signed-off-by: celtare21 <[email protected]>
celtare21 · Dec 16, 2022 · 9078172 · 9078172
1 parent 4c06752
commit 9078172
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
@@ -705,6 +705,9 @@ static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
 	size_t len = iov_iter_count(from);
 	ssize_t ret = len;
 
+	/* Don't allow userspace to write to /dev/kmesg */
+	return len;
+
 	if (!user || len > LOG_LINE_MAX)
 		return -EINVAL;