Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [RFC 04/16] kgr: add testing kgraft patch | Date | Wed, 30 Apr 2014 16:30:37 +0200 |
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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@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.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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