From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752191AbbKJEqO (ORCPT ); Mon, 9 Nov 2015 23:46:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44478 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752059AbbKJEqF (ORCPT ); Mon, 9 Nov 2015 23:46:05 -0500 From: Jessica Yu To: Rusty Russell , Josh Poimboeuf , Seth Jennings , Jiri Kosina , Vojtech Pavlik , Miroslav Benes Cc: linux-api@vger.kernel.org, live-patching@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Jessica Yu Subject: [RFC PATCH 2/5] module: save load_info for livepatch modules Date: Mon, 9 Nov 2015 23:45:52 -0500 Message-Id: <1447130755-17383-3-git-send-email-jeyu@redhat.com> In-Reply-To: <1447130755-17383-1-git-send-email-jeyu@redhat.com> References: <1447130755-17383-1-git-send-email-jeyu@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In livepatch modules, preserve section, symbol, string information from the load_info struct in the module loader. This information is used to patch modules that are not loaded in memory yet; specifically it is used to resolve remaining symbols and write relocations when the target module loads. Signed-off-by: Jessica Yu --- include/linux/module.h | 25 +++++++++++++++++++++++++ kernel/livepatch/core.c | 17 +++++++++++++++++ kernel/module.c | 36 ++++++++++++++++++++++-------------- 3 files changed, 64 insertions(+), 14 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 3a19c79..c8680b1 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -36,6 +36,20 @@ struct modversion_info { char name[MODULE_NAME_LEN]; }; +struct load_info { + Elf_Ehdr *hdr; + unsigned long len; + Elf_Shdr *sechdrs; + char *secstrings, *strtab; + unsigned long symoffs, stroffs; + struct _ddebug *debug; + unsigned int num_debug; + bool sig_ok; + struct { + unsigned int sym, str, mod, vers, info, pcpu; + } index; +}; + struct module; struct module_kobject { @@ -462,6 +476,8 @@ struct module { #ifdef CONFIG_LIVEPATCH bool klp_alive; + /* save info to patch to-be-loaded modules */ + struct load_info *info; #endif #ifdef CONFIG_MODULE_UNLOAD @@ -635,6 +651,15 @@ static inline bool module_requested_async_probing(struct module *module) return module && module->async_probe_requested; } +#ifdef CONFIG_LIVEPATCH +extern void klp_prepare_patch_module(struct module *mod, + struct load_info *info); +extern int +apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, + unsigned int symindex, unsigned int relsec, + struct module *me); +#endif + #else /* !CONFIG_MODULES... */ /* Given an address, look for it in the exception tables. */ diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 6e53441..087a8c7 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -1001,6 +1001,23 @@ static struct notifier_block klp_module_nb = { .priority = INT_MIN+1, /* called late but before ftrace notifier */ }; +/* + * Save necessary information from info in order to be able to + * patch modules that might be loaded later + */ +void klp_prepare_patch_module(struct module *mod, struct load_info *info) +{ + Elf_Shdr *symsect; + + symsect = info->sechdrs + info->index.sym; + /* update sh_addr to point to symtab */ + symsect->sh_addr = (unsigned long)info->hdr + symsect->sh_offset; + + mod->info = kzalloc(sizeof(*info), GFP_KERNEL); + memcpy(mod->info, info, sizeof(*info)); + +} + static int __init klp_init(void) { int ret; diff --git a/kernel/module.c b/kernel/module.c index 8f051a1..8ae3ca5 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -318,20 +318,6 @@ int unregister_module_notifier(struct notifier_block *nb) } EXPORT_SYMBOL(unregister_module_notifier); -struct load_info { - Elf_Ehdr *hdr; - unsigned long len; - Elf_Shdr *sechdrs; - char *secstrings, *strtab; - unsigned long symoffs, stroffs; - struct _ddebug *debug; - unsigned int num_debug; - bool sig_ok; - struct { - unsigned int sym, str, mod, vers, info, pcpu; - } index; -}; - /* We require a truly strong try_module_get(): 0 means failure due to ongoing or failed initialization etc. */ static inline int strong_try_module_get(struct module *mod) @@ -2137,6 +2123,11 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) (long)sym[i].st_value); break; +#ifdef CONFIG_LIVEPATCH + case SHN_LIVEPATCH: + break; +#endif + case SHN_UNDEF: ksym = resolve_symbol_wait(mod, info, name); /* Ok if resolved. */ @@ -2185,6 +2176,11 @@ static int apply_relocations(struct module *mod, const struct load_info *info) if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) continue; +#ifdef CONFIG_LIVEPATCH + if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) + continue; +#endif + if (info->sechdrs[i].sh_type == SHT_REL) err = apply_relocate(info->sechdrs, info->strtab, info->index.sym, i, mod); @@ -3530,8 +3526,20 @@ static int load_module(struct load_info *info, const char __user *uargs, if (err < 0) goto bug_cleanup; +#ifdef CONFIG_LIVEPATCH + /* + * Save sechdrs, indices, and other data from info + * in order to patch to-be-loaded modules. + * Do not call free_copy() for livepatch modules. + */ + if (get_modinfo((struct load_info *)info, "livepatch")) + klp_prepare_patch_module(mod, info); + else + free_copy(info); +#else /* Get rid of temporary copy. */ free_copy(info); +#endif /* Done! */ trace_module_load(mod); -- 2.4.3