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Date: Wed, 30 Apr 2014 16:30:37 +0200
From: Jiri Slaby <jslaby@...e.cz>
To: linux-kernel@...r.kernel.org
Cc: jirislaby@...il.com, Vojtech Pavlik <vojtech@...e.cz>,
Michael Matz <matz@...e.de>, Jiri Kosina <jkosina@...e.cz>,
Jiri Slaby <jslaby@...e.cz>,
Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Ingo Molnar <mingo@...hat.com>
Subject: [RFC 04/16] kgr: add testing kgraft patch
This is intended to be a presentation of the kgraft engine, so it is
placed into samples/ directory.
It patches sys_iopl() and sys_capable() to print an additional message
to the original functionality.
Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...hat.com>
---
samples/Kconfig | 4 ++
samples/Makefile | 3 +-
samples/kgr/Makefile | 1 +
samples/kgr/kgr_patcher.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 104 insertions(+), 1 deletion(-)
create mode 100644 samples/kgr/Makefile
create mode 100644 samples/kgr/kgr_patcher.c
diff --git a/samples/Kconfig b/samples/Kconfig
index 6181c2cc9ca0..a923510443de 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -55,6 +55,10 @@ config SAMPLE_KDB
Build an example of how to dynamically add the hello
command to the kdb shell.
+config SAMPLE_KGR_PATCHER
+ tristate "Build kgr patcher example -- loadable modules only"
+ depends on KGR && m
+
config SAMPLE_RPMSG_CLIENT
tristate "Build rpmsg client sample -- loadable modules only"
depends on RPMSG && m
diff --git a/samples/Makefile b/samples/Makefile
index 1a60c62e2045..a141b219c019 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,5 @@
# Makefile for Linux samples code
obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ \
- hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
+ hw_breakpoint/ kfifo/ kdb/ kgr/ \
+ hidraw/ rpmsg/ seccomp/
diff --git a/samples/kgr/Makefile b/samples/kgr/Makefile
new file mode 100644
index 000000000000..202eee7d050e
--- /dev/null
+++ b/samples/kgr/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KGR_PATCHER) += kgr_patcher.o
diff --git a/samples/kgr/kgr_patcher.c b/samples/kgr/kgr_patcher.c
new file mode 100644
index 000000000000..828543e36f3f
--- /dev/null
+++ b/samples/kgr/kgr_patcher.c
@@ -0,0 +1,97 @@
+/*
+ * kgr_patcher -- just kick kgr infrastructure for test
+ *
+ * Copyright (c) 2013-2014 SUSE
+ * Authors: Jiri Kosina
+ * Vojtech Pavlik
+ * Jiri Slaby
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/kgr.h>
+#include <linux/kallsyms.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/capability.h>
+#include <linux/ptrace.h>
+
+#include <asm/processor.h>
+
+/*
+ * This all should be autogenerated from the patched sources
+ *
+ * IMPORTANT TODO: we have to handle cases where the new code is calling out
+ * into functions which are not exported to modules.
+ *
+ * This can either be handled by calling all such functions indirectly, i.e
+ * obtaining pointer from kallsyms in the stub (and transforming all callsites
+ * to do pointer dereference), or by modifying the kernel module linker.
+ */
+
+asmlinkage long kgr_new_sys_iopl(unsigned int level)
+{
+ struct pt_regs *regs = current_pt_regs();
+ unsigned int old = (regs->flags >> 12) & 3;
+ struct thread_struct *t = ¤t->thread;
+
+ printk(KERN_DEBUG "kgr-patcher: this is a new sys_iopl()\n");
+
+ if (level > 3)
+ return -EINVAL;
+ /* Trying to gain more privileges? */
+ if (level > old) {
+ if (!capable(CAP_SYS_RAWIO))
+ return -EPERM;
+ }
+ regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
+ t->iopl = level << 12;
+ set_iopl_mask(t->iopl);
+
+ return 0;
+}
+KGR_PATCHED_FUNCTION(patch, SyS_iopl, kgr_new_sys_iopl);
+
+static bool new_capable(int cap)
+{
+ printk(KERN_DEBUG "kgr-patcher: this is a new capable()\n");
+
+ return ns_capable(&init_user_ns, cap);
+}
+KGR_PATCHED_FUNCTION(patch, capable, new_capable);
+
+static const struct kgr_patch patch = {
+ .patches = {
+ KGR_PATCH(SyS_iopl),
+ KGR_PATCH(capable),
+ KGR_PATCH_END
+ }
+};
+
+static int __init kgr_patcher_init(void)
+{
+ /* removing not supported (yet?) */
+ __module_get(THIS_MODULE);
+ kgr_start_patching(&patch);
+ return 0;
+}
+
+static void __exit kgr_patcher_cleanup(void)
+{
+ /* extra care needs to be taken when freeing ftrace_ops->private */
+ printk(KERN_ERR "removing now buggy!\n");
+}
+
+module_init(kgr_patcher_init);
+module_exit(kgr_patcher_cleanup);
+
+MODULE_LICENSE("GPL");
+
--
1.9.2
--
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