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b2b018ef48
Currently, patching objects with duplicate symbol names fail because the creation of the sysfs function directory collides with the previous attempt. Appending old_addr to the function name is problematic as it reveals the address of the function being patch to a normal user. Using the symbol's occurrence in kallsyms to postfix the function name in the sysfs directory solves the issue of having consistent unique names and ensuring that the address is not exposed to a normal user. In addition, using the symbol position as the user's method to disambiguate symbols instead of addr allows for disambiguating symbols in modules as well for both function addresses and for relocs. This also simplifies much of the code. Special handling for kASLR is no longer needed and can be removed. The klp_find_verify_func_addr function can be replaced by klp_find_object_symbol, and klp_verify_vmlinux_symbol and its callback can be removed completely. In cases of duplicate symbols, old_sympos will be used to disambiguate instead of old_addr. By default old_sympos will be 0, and patching will only succeed if the symbol is unique. Specifying a positive value will ensure that occurrence of the symbol in kallsyms for the patched object will be used for patching if it is valid. In addition, make old_addr an internal structure field not to be specified by the user. Finally, remove klp_find_verify_func_addr as it can be replaced by klp_find_object_symbol directly. Support for symbol position disambiguation for relocations is added in the next patch in this series. Signed-off-by: Chris J Arges <chris.j.arges@canonical.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
141 lines
4.0 KiB
C
141 lines
4.0 KiB
C
/*
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* livepatch.h - Kernel Live Patching Core
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*
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* Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
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* Copyright (C) 2014 SUSE
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _LINUX_LIVEPATCH_H_
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#define _LINUX_LIVEPATCH_H_
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#if IS_ENABLED(CONFIG_LIVEPATCH)
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#include <asm/livepatch.h>
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enum klp_state {
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KLP_DISABLED,
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KLP_ENABLED
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};
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/**
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* struct klp_func - function structure for live patching
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* @old_name: name of the function to be patched
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* @new_func: pointer to the patched function code
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* @old_sympos: a hint indicating which symbol position the old function
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* can be found (optional)
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* @old_addr: the address of the function being patched
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* @kobj: kobject for sysfs resources
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* @state: tracks function-level patch application state
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* @stack_node: list node for klp_ops func_stack list
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*/
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struct klp_func {
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/* external */
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const char *old_name;
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void *new_func;
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/*
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* The old_sympos field is optional and can be used to resolve
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* duplicate symbol names in livepatch objects. If this field is zero,
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* it is expected the symbol is unique, otherwise patching fails. If
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* this value is greater than zero then that occurrence of the symbol
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* in kallsyms for the given object is used.
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*/
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unsigned long old_sympos;
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/* internal */
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unsigned long old_addr;
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struct kobject kobj;
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enum klp_state state;
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struct list_head stack_node;
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};
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/**
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* struct klp_reloc - relocation structure for live patching
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* @loc: address where the relocation will be written
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* @val: address of the referenced symbol (optional,
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* vmlinux patches only)
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* @type: ELF relocation type
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* @name: name of the referenced symbol (for lookup/verification)
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* @addend: offset from the referenced symbol
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* @external: symbol is either exported or within the live patch module itself
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*/
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struct klp_reloc {
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unsigned long loc;
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unsigned long val;
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unsigned long type;
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const char *name;
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int addend;
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int external;
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};
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/**
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* struct klp_object - kernel object structure for live patching
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* @name: module name (or NULL for vmlinux)
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* @relocs: relocation entries to be applied at load time
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* @funcs: function entries for functions to be patched in the object
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* @kobj: kobject for sysfs resources
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* @mod: kernel module associated with the patched object
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* (NULL for vmlinux)
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* @state: tracks object-level patch application state
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*/
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struct klp_object {
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/* external */
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const char *name;
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struct klp_reloc *relocs;
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struct klp_func *funcs;
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/* internal */
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struct kobject kobj;
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struct module *mod;
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enum klp_state state;
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};
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/**
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* struct klp_patch - patch structure for live patching
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* @mod: reference to the live patch module
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* @objs: object entries for kernel objects to be patched
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* @list: list node for global list of registered patches
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* @kobj: kobject for sysfs resources
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* @state: tracks patch-level application state
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*/
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struct klp_patch {
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/* external */
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struct module *mod;
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struct klp_object *objs;
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/* internal */
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struct list_head list;
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struct kobject kobj;
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enum klp_state state;
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};
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#define klp_for_each_object(patch, obj) \
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for (obj = patch->objs; obj->funcs; obj++)
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#define klp_for_each_func(obj, func) \
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for (func = obj->funcs; func->old_name; func++)
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int klp_register_patch(struct klp_patch *);
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int klp_unregister_patch(struct klp_patch *);
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int klp_enable_patch(struct klp_patch *);
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int klp_disable_patch(struct klp_patch *);
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#endif /* CONFIG_LIVEPATCH */
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#endif /* _LINUX_LIVEPATCH_H_ */
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