(2014/11/26 2:15), Seth Jennings wrote: > This commit introduces code for the live patching core. It implements > an ftrace-based mechanism and kernel interface for doing live patching > of kernel and kernel module functions. > > It represents the greatest common functionality set between kpatch and > kgraft and can accept patches built using either method. > > This first version does not implement any consistency mechanism that > ensures that old and new code do not run together. In practice, ~90% of > CVEs are safe to apply in this way, since they simply add a conditional > check. However, any function change that can not execute safely with > the old version of the function can _not_ be safely applied in this > version.
Thank you for updating the patch :) [...] > diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h > new file mode 100644 > index 0000000..4e01b59 > --- /dev/null > +++ b/include/linux/livepatch.h > @@ -0,0 +1,121 @@ > +/* > + * livepatch.h - Kernel Live Patching Core > + * > + * Copyright (C) 2014 Seth Jennings <sjenn...@redhat.com> > + * > + * 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. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * You should have received a copy of the GNU General Public License > + * along with this program; if not, see <http://www.gnu.org/licenses/>. > + */ > + > +#ifndef _LINUX_LIVEPATCH_H_ > +#define _LINUX_LIVEPATCH_H_ > + > +#include <linux/module.h> > +#include <linux/ftrace.h> > + > +#if IS_ENABLED(CONFIG_LIVE_PATCHING) > + > +#include <asm/livepatch.h> > + > +enum klp_state { > + KLP_DISABLED, > + KLP_ENABLED > +}; > + > +/** > + * struct klp_func - function structure for live patching > + * @old_name: name of the function to be patched > + * @new_func: pointer to the patched function code > + * @old_addr: a hint conveying at what address the old function > + * can be found (optional, vmlinux patches only) > + */ > +struct klp_func { > + /* external */ > + const char *old_name; > + void *new_func; > + /* > + * The old_addr field is optional and can be used to resolve > + * duplicate symbol names in the vmlinux object. If this > + * information is not present, the symbol is located by name > + * with kallsyms. If the name is not unique and old_addr is > + * not provided, the patch application fails as there is no > + * way to resolve the ambiguity. > + */ > + unsigned long old_addr; > + > + /* internal */ > + struct kobject kobj; > + struct ftrace_ops *fops; > + enum klp_state state; > +}; > + > +/** > + * struct klp_reloc - relocation structure for live patching > + * @dest address where the relocation will be written > + * @src address of the referenced symbol (optional, > + * vmlinux patches only) > + * @type ELF relocation type > + * @name name of the referenced symbol (for lookup/verification) > + * @addend offset from the referenced symbol > + * @external symbol is either exported or within the live patch module itself > + */ > +struct klp_reloc { > + unsigned long dest; > + unsigned long src; > + unsigned long type; > + const char *name; > + int addend; BTW, where would the "addend" come from? I guess we can use "offset" instead. > + int external; > +}; > + > +/* struct klp_object - kernel object structure for live patching > + * @name module name (or NULL for vmlinux) > + * @relocs relocation entries to be applied at load time > + * @funcs function entries for functions to be patched in the object > + */ > +struct klp_object { > + /* external */ > + const char *name; > + struct klp_reloc *relocs; > + struct klp_func *funcs; > + > + /* internal */ > + struct kobject *kobj; > + struct module *mod; > + enum klp_state state; > +}; > + > +/** > + * struct klp_patch - patch structure for live patching > + * @mod reference to the live patch module > + * @objs object entries for kernel objects to be patched > + */ > +struct klp_patch { > + /* external */ > + struct module *mod; > + struct klp_object *objs; > + > + /* internal */ > + struct list_head list; > + struct kobject kobj; > + enum klp_state state; > +}; > + > +extern int klp_register_patch(struct klp_patch *); > +extern int klp_unregister_patch(struct klp_patch *); > +extern int klp_enable_patch(struct klp_patch *); > +extern int klp_disable_patch(struct klp_patch *); > + > +#endif /* CONFIG_LIVE_PATCHING */ > + > +#endif /* _LINUX_LIVEPATCH_H_ */ > diff --git a/kernel/Makefile b/kernel/Makefile > index a59481a..616994f 100644 > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -26,6 +26,7 @@ obj-y += power/ > obj-y += printk/ > obj-y += irq/ > obj-y += rcu/ > +obj-y += livepatch/ > > obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o > obj-$(CONFIG_FREEZER) += freezer.o > diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig > new file mode 100644 > index 0000000..96da00f > --- /dev/null > +++ b/kernel/livepatch/Kconfig > @@ -0,0 +1,18 @@ > +config ARCH_HAVE_LIVE_PATCHING > + boolean > + help > + Arch supports kernel live patching > + > +config LIVE_PATCHING > + boolean "Kernel Live Patching" > + depends on DYNAMIC_FTRACE_WITH_REGS > + depends on MODULES > + depends on SYSFS > + depends on KALLSYMS_ALL > + depends on ARCH_HAVE_LIVE_PATCHING > + help > + Say Y here if you want to support kernel live patching. > + This option has no runtime impact until a kernel "patch" > + module uses the interface provided by this option to register > + a patch, causing calls to patched functions to be redirected > + to new function code contained in the patch module. > diff --git a/kernel/livepatch/Makefile b/kernel/livepatch/Makefile BTW, until establishing the consistency models and engines, this would better depend on EXPERIMENTAL flag :) Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
