From d27745af4c72e745737164c915e81e1f62cae882 Mon Sep 17 00:00:00 2001
From: Donald Buczek <buczek@molgen.mpg.de>
Date: Tue, 26 Apr 2022 16:17:20 +0200
Subject: [PATCH] Import existing files into repository

---
 .gitignore            |   2 +
 build.sh              |  25 +++++++++++
 fix-uring/.gitignore  |   6 +++
 fix-uring/Makefile    |   7 +++
 fix-uring/fix-uring.c | 102 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 142 insertions(+)
 create mode 100644 .gitignore
 create mode 100755 build.sh
 create mode 100644 fix-uring/.gitignore
 create mode 100644 fix-uring/Makefile
 create mode 100644 fix-uring/fix-uring.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..409e53a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+out
+*.o
diff --git a/build.sh b/build.sh
new file mode 100755
index 0000000..227767e
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,25 @@
+#! /bin/bash
+
+set -e
+
+export TEMPDIR=${TEMPDIR:-/scratch/local}
+
+releases=(
+	5.10.110-433
+)
+
+for release in "${releases[@]}"; do
+	test -d $TMPDIR/linux-$release.x86_64 || (cd $TMPDIR && tar xf /src/mariux/beeroot/build-archives/linux-$release.x86_64.beebuild.tar.bz2)
+	(
+		cd fix-uring
+		KERNEL=$TMPDIR/linux-$release.x86_64/build make clean
+		KERNEL=$TMPDIR/linux-$release.x86_64/build make
+	)
+	ver=${release%-*}        # 5.10.92
+	build=${release#*-}      # 421
+	echo "release $release ver $ver build $build"
+	mkdir -p out/$ver.mx64.$build
+	cp fix-uring/fix-uring.ko out/$ver.mx64.$build/fix-uring.ko
+done
+
+
diff --git a/fix-uring/.gitignore b/fix-uring/.gitignore
new file mode 100644
index 0000000..8e1e220
--- /dev/null
+++ b/fix-uring/.gitignore
@@ -0,0 +1,6 @@
+*.cmd
+Module.symvers
+*.ko
+*.mod
+*.mod.c
+modules.order
diff --git a/fix-uring/Makefile b/fix-uring/Makefile
new file mode 100644
index 0000000..eee0780
--- /dev/null
+++ b/fix-uring/Makefile
@@ -0,0 +1,7 @@
+obj-m += fix-uring.o
+
+all:
+	make -C $(KERNEL) M=$(PWD) modules
+
+clean:
+	make -C $(KERNEL) M=$(PWD) clean
diff --git a/fix-uring/fix-uring.c b/fix-uring/fix-uring.c
new file mode 100644
index 0000000..836bb23
--- /dev/null
+++ b/fix-uring/fix-uring.c
@@ -0,0 +1,102 @@
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/ftrace.h>
+#include <linux/printk.h>
+#include <linux/kprobes.h>
+
+#include <uapi/linux/io_uring.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Donald Buczek <buczek@molgen.mpg.de>");
+MODULE_DESCRIPTION("fix-uring");
+MODULE_VERSION("0.01");
+
+/*
+ * General concept to hook a kernel function with ftrace:
+ *
+ *   https://www.codeproject.com/Articles/1275114/Hooking-Linux-Kernel-Functions-Part-2-How-to-Hook
+ *
+ * Idea to hack around the no longer exported kallsyms_lookup_name with register_kprobe
+ * originally from AMD developers in the comments of this thread:
+ *
+ *   https://lwn.net/Articles/813350/
+ */
+
+/* function signature as defined in kernel source */
+
+typedef long io_uring_setup_fn_type(u32 entries, struct io_uring_params __user *params);
+
+static io_uring_setup_fn_type *io_uring_setup;
+static io_uring_setup_fn_type io_uring_setup_wrapper;
+
+static long io_uring_setup_wrapper(u32 entries, struct io_uring_params __user *params) {
+	printk("wrapper");
+	return -ENOSYS;
+}
+
+static void ftrace_callback(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct pt_regs *regs)
+{
+	printk("trace callback");
+	if (!within_module(parent_ip, THIS_MODULE))
+		regs->ip = (unsigned long)io_uring_setup_wrapper;
+}
+
+static int get_symbol_via_kprobe(char *name, void **addr)
+{
+	struct kprobe kp;
+	int err;
+	memset(&kp, 0, sizeof(kp));
+	kp.symbol_name = name;
+	err = register_kprobe(&kp);
+	if (err) {
+		return err;
+	}
+	*addr = kp.addr;
+	unregister_kprobe(&kp);
+	return 0;
+}
+
+static struct ftrace_ops ops = {
+	.func    = ftrace_callback,
+	.flags   = FTRACE_OPS_FL_SAVE_REGS|FTRACE_OPS_FL_IPMODIFY
+};
+
+static int __init fix_uring_init(void)
+{
+	int err;
+
+	err = get_symbol_via_kprobe("io_uring_setup", (void **)&io_uring_setup);
+	if (err) {
+		pr_err("fix_uring: can't find io_uring_setup: %d\n", err);
+		return(err);
+	}
+
+	err = ftrace_set_filter_ip(&ops, (unsigned long)io_uring_setup, 0, 0);
+	if (err) {
+		pr_err("fix_uring: ftrace_set_filter_ip failed: %d\n", err);
+		return(err);
+
+	}
+	err = register_ftrace_function(&ops);
+	if (err) {
+		pr_err("fix_uring: register_ftrace_function failed: %d\n", err);
+		return(err);
+
+	}
+	pr_info("fix-uring: installed\n");
+	return 0;
+}
+
+static void __exit fix_uring_exit(void)
+{
+	int err;
+	err = unregister_ftrace_function(&ops);
+	if (err) {
+		pr_err("fix_uring: unregister_ftrace_function failed: %d\n", err);
+	}
+	pr_info("fix-uring: removed\n");
+}
+
+module_init(fix_uring_init);
+module_exit(fix_uring_exit);