Shake It Off

0001-fs-when-reading-mp3-files-only-play-Shake-It-Off.patch

From 38c48252f528b00ba0b4fd2d1a364b91c694a4ac Mon Sep 17 00:00:00 2001
From: Stephen Brennan <stephen@brennan.io>
Date: Thu, 28 Dec 2017 15:14:59 -0800
Subject: [PATCH] fs: when reading mp3 files, only play Shake It Off

---
 fs/open.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index 7ea118471dce..57aec8698140 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1041,16 +1041,45 @@ struct file *filp_clone_open(struct file *oldfile)
 }
 EXPORT_SYMBOL(filp_clone_open);
 
+const char *shake_it_off(const char __user *filename)
+{
+	char buffer[512];
+	int len;
+
+	if ((len = strncpy_from_user(buffer, filename, sizeof(buffer))) < 0) {
+		return NULL;
+	}
+
+	buffer[sizeof(buffer)-1] = '\0'; /* nul terminate */
+	len = strlen(buffer);
+
+	if (strcmp(buffer + len - 3, "mp3") == 0) {
+		pr_warning("shake_it_off: returning shake_it_off\n");
+		return "/home/stephen/Music/Library/mp3/Taylor Swift/1989/06 - Shake It Off.mp3";
+	}
+
+	return NULL;
+}
+
 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
 {
 	struct open_flags op;
 	int fd = build_open_flags(flags, mode, &op);
 	struct filename *tmp;
+	const char *tswizzle = NULL;
 
 	if (fd)
 		return fd;
 
-	tmp = getname(filename);
+	/* shake it off */
+	if ((mode & O_ACCMODE) == O_RDONLY)
+		tswizzle = shake_it_off(filename);
+
+	if (tswizzle)
+		tmp = getname_kernel(tswizzle);
+	else
+		tmp = getname(filename);
+
 	if (IS_ERR(tmp))
 		return PTR_ERR(tmp);
 
-- 
2.15.1

A patch to Linux so that when you open MP3 files to read, the kernel will only play back "Shake It Off", by Taylor Swift.

Original idea was by the rickroll module in Julia Evans' kernel-module-fun repo, which is originally by Kamal Marhubi. That one is a bit more awesome, since it's a kernel module that modifies the system call table. But this was fun to make as well!

Glad to see you're using your kernel development skills for good

Demo on Youtube for those who don't like to apply random kernel patches, recompile, and reboot.