From bf262dcec6383188a3324192c4a7e405b3b1ad23 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Tue, 12 Apr 2016 05:02:09 +0930 Subject: module: fix noreturn attribute for __module_put_and_exit() __module_put_and_exit() is makred noreturn in module.h declaration, but is lacking the attribute in the definition, which makes some tools (such as sparse) unhappy. Amend the definition with the attribute as well (and reformat the declaration so that it uses more common format). Signed-off-by: Jiri Kosina Signed-off-by: Rusty Russell --- include/linux/module.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/module.h b/include/linux/module.h index 3daf2b3a09d2..f777164c238b 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -575,8 +575,8 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, unsigned long), void *data); -extern void __module_put_and_exit(struct module *mod, long code) - __attribute__((noreturn)); +extern void __noreturn __module_put_and_exit(struct module *mod, + long code); #define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code) #ifdef CONFIG_MODULE_UNLOAD -- cgit v1.2.3 From 0ef7653797addea8ba1bf97f8208a54a62498d94 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 27 Jul 2016 12:06:34 +0930 Subject: exceptions: fork exception table content from module.h into extable.h For historical reasons (i.e. pre-git) the exception table stuff was buried in the middle of the module.h file. I noticed this while doing an audit for needless includes of module.h and found core kernel files (both arch specific and arch independent) were just including module.h for this. The converse is also true, in that conventional drivers, be they for filesystems or actual hardware peripherals or similar, do not normally care about the exception tables. Here we fork the exception table content out of module.h into a new file called extable.h -- and temporarily include it into the module.h itself. Then we will work our way across the arch independent and arch specific files needing just exception table content, and move them off module.h and onto extable.h Once that is done, we can remove the extable.h from module.h and in doing it like this, we avoid introducing build failures into the git history. The gain here is that module.h gets a bit smaller, across all modular drivers that we build for allmodconfig. Also the core files that only need exception table stuff don't have an include of module.h that brings in lots of extra stuff and just looks generally out of place. Cc: Andrew Morton Cc: Linus Torvalds Signed-off-by: Paul Gortmaker Signed-off-by: Rusty Russell --- include/linux/extable.h | 30 ++++++++++++++++++++++++++++++ include/linux/module.h | 27 ++------------------------- 2 files changed, 32 insertions(+), 25 deletions(-) create mode 100644 include/linux/extable.h (limited to 'include') diff --git a/include/linux/extable.h b/include/linux/extable.h new file mode 100644 index 000000000000..2c71dccd1bc3 --- /dev/null +++ b/include/linux/extable.h @@ -0,0 +1,30 @@ +#ifndef _LINUX_EXTABLE_H +#define _LINUX_EXTABLE_H + +struct module; +struct exception_table_entry; + +const struct exception_table_entry * +search_extable(const struct exception_table_entry *first, + const struct exception_table_entry *last, + unsigned long value); +void sort_extable(struct exception_table_entry *start, + struct exception_table_entry *finish); +void sort_main_extable(void); +void trim_init_extable(struct module *m); + +/* Given an address, look for it in the exception tables */ +const struct exception_table_entry *search_exception_tables(unsigned long add); + +#ifdef CONFIG_MODULES +/* For extable.c to search modules' exception tables. */ +const struct exception_table_entry *search_module_extables(unsigned long addr); +#else +static inline const struct exception_table_entry * +search_module_extables(unsigned long addr) +{ + return NULL; +} +#endif /*CONFIG_MODULES*/ + +#endif /* _LINUX_EXTABLE_H */ diff --git a/include/linux/module.h b/include/linux/module.h index f777164c238b..f95ed243a4de 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -18,6 +18,7 @@ #include #include #include +#include /* only as arch move module.h -> extable.h */ #include #include @@ -37,6 +38,7 @@ struct modversion_info { }; struct module; +struct exception_table_entry; struct module_kobject { struct kobject kobj; @@ -155,18 +157,6 @@ extern void cleanup_module(void); #define __INITRODATA_OR_MODULE __INITRODATA #endif /*CONFIG_MODULES*/ -/* Archs provide a method of finding the correct exception table. */ -struct exception_table_entry; - -const struct exception_table_entry * -search_extable(const struct exception_table_entry *first, - const struct exception_table_entry *last, - unsigned long value); -void sort_extable(struct exception_table_entry *start, - struct exception_table_entry *finish); -void sort_main_extable(void); -void trim_init_extable(struct module *m); - /* Generic info of form tag = "info" */ #define MODULE_INFO(tag, info) __MODULE_INFO(tag, tag, info) @@ -268,9 +258,6 @@ extern const typeof(name) __mod_##type##__##name##_device_table \ * files require multiple MODULE_FIRMWARE() specifiers */ #define MODULE_FIRMWARE(_firmware) MODULE_INFO(firmware, _firmware) -/* Given an address, look for it in the exception tables */ -const struct exception_table_entry *search_exception_tables(unsigned long add); - struct notifier_block; #ifdef CONFIG_MODULES @@ -630,9 +617,6 @@ const char *module_address_lookup(unsigned long addr, int lookup_module_symbol_name(unsigned long addr, char *symname); int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name); -/* For extable.c to search modules' exception tables. */ -const struct exception_table_entry *search_module_extables(unsigned long addr); - int register_module_notifier(struct notifier_block *nb); int unregister_module_notifier(struct notifier_block *nb); @@ -657,13 +641,6 @@ static inline bool is_livepatch_module(struct module *mod) #else /* !CONFIG_MODULES... */ -/* Given an address, look for it in the exception tables. */ -static inline const struct exception_table_entry * -search_module_extables(unsigned long addr) -{ - return NULL; -} - static inline struct module *__module_address(unsigned long addr) { return NULL; -- cgit v1.2.3 From 444d13ff10fb13bc3e64859c3cf9ce43dcfeb075 Mon Sep 17 00:00:00 2001 From: Jessica Yu Date: Wed, 27 Jul 2016 12:06:21 +0930 Subject: modules: add ro_after_init support Add ro_after_init support for modules by adding a new page-aligned section in the module layout (after rodata) for ro_after_init data and enabling RO protection for that section after module init runs. Signed-off-by: Jessica Yu Acked-by: Kees Cook Signed-off-by: Rusty Russell --- include/linux/module.h | 6 +++-- include/uapi/linux/elf.h | 1 + kernel/livepatch/core.c | 2 +- kernel/module.c | 66 +++++++++++++++++++++++++++++++++++++++--------- 4 files changed, 60 insertions(+), 15 deletions(-) (limited to 'include') diff --git a/include/linux/module.h b/include/linux/module.h index f95ed243a4de..0c3207d26ac0 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -298,6 +298,8 @@ struct module_layout { unsigned int text_size; /* Size of RO section of the module (text+rodata) */ unsigned int ro_size; + /* Size of RO after init section */ + unsigned int ro_after_init_size; #ifdef CONFIG_MODULES_TREE_LOOKUP struct mod_tree_node mtn; @@ -765,12 +767,12 @@ extern int module_sysfs_initialized; #ifdef CONFIG_DEBUG_SET_MODULE_RONX extern void set_all_modules_text_rw(void); extern void set_all_modules_text_ro(void); -extern void module_enable_ro(const struct module *mod); +extern void module_enable_ro(const struct module *mod, bool after_init); extern void module_disable_ro(const struct module *mod); #else static inline void set_all_modules_text_rw(void) { } static inline void set_all_modules_text_ro(void) { } -static inline void module_enable_ro(const struct module *mod) { } +static inline void module_enable_ro(const struct module *mod, bool after_init) { } static inline void module_disable_ro(const struct module *mod) { } #endif diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index cb4a72f888d5..70b172ba41ce 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -286,6 +286,7 @@ typedef struct elf64_phdr { #define SHF_ALLOC 0x2 #define SHF_EXECINSTR 0x4 #define SHF_RELA_LIVEPATCH 0x00100000 +#define SHF_RO_AFTER_INIT 0x00200000 #define SHF_MASKPROC 0xf0000000 /* special section indexes */ diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index 5c2bc1052691..8bbe50704621 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -309,7 +309,7 @@ static int klp_write_object_relocations(struct module *pmod, break; } - module_enable_ro(pmod); + module_enable_ro(pmod, true); return ret; } diff --git a/kernel/module.c b/kernel/module.c index c91c2fdca2e6..205a71a97852 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1857,10 +1857,11 @@ static void mod_sysfs_teardown(struct module *mod) * from modification and any data from execution. * * General layout of module is: - * [text] [read-only-data] [writable data] - * text_size -----^ ^ ^ - * ro_size ------------------------| | - * size -------------------------------------------| + * [text] [read-only-data] [ro-after-init] [writable data] + * text_size -----^ ^ ^ ^ + * ro_size ------------------------| | | + * ro_after_init_size -----------------------------| | + * size -----------------------------------------------------------| * * These values are always page-aligned (as is base) */ @@ -1883,14 +1884,24 @@ static void frob_rodata(const struct module_layout *layout, (layout->ro_size - layout->text_size) >> PAGE_SHIFT); } +static void frob_ro_after_init(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) +{ + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); + set_memory((unsigned long)layout->base + layout->ro_size, + (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); +} + static void frob_writable_data(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->ro_size, - (layout->size - layout->ro_size) >> PAGE_SHIFT); + set_memory((unsigned long)layout->base + layout->ro_after_init_size, + (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); } /* livepatching wants to disable read-only so it can frob module. */ @@ -1898,21 +1909,26 @@ void module_disable_ro(const struct module *mod) { frob_text(&mod->core_layout, set_memory_rw); frob_rodata(&mod->core_layout, set_memory_rw); + frob_ro_after_init(&mod->core_layout, set_memory_rw); frob_text(&mod->init_layout, set_memory_rw); frob_rodata(&mod->init_layout, set_memory_rw); } -void module_enable_ro(const struct module *mod) +void module_enable_ro(const struct module *mod, bool after_init) { frob_text(&mod->core_layout, set_memory_ro); frob_rodata(&mod->core_layout, set_memory_ro); frob_text(&mod->init_layout, set_memory_ro); frob_rodata(&mod->init_layout, set_memory_ro); + + if (after_init) + frob_ro_after_init(&mod->core_layout, set_memory_ro); } static void module_enable_nx(const struct module *mod) { frob_rodata(&mod->core_layout, set_memory_nx); + frob_ro_after_init(&mod->core_layout, set_memory_nx); frob_writable_data(&mod->core_layout, set_memory_nx); frob_rodata(&mod->init_layout, set_memory_nx); frob_writable_data(&mod->init_layout, set_memory_nx); @@ -1921,6 +1937,7 @@ static void module_enable_nx(const struct module *mod) static void module_disable_nx(const struct module *mod) { frob_rodata(&mod->core_layout, set_memory_x); + frob_ro_after_init(&mod->core_layout, set_memory_x); frob_writable_data(&mod->core_layout, set_memory_x); frob_rodata(&mod->init_layout, set_memory_x); frob_writable_data(&mod->init_layout, set_memory_x); @@ -1963,6 +1980,8 @@ static void disable_ro_nx(const struct module_layout *layout) frob_text(layout, set_memory_rw); frob_rodata(layout, set_memory_rw); frob_rodata(layout, set_memory_x); + frob_ro_after_init(layout, set_memory_rw); + frob_ro_after_init(layout, set_memory_x); frob_writable_data(layout, set_memory_x); } @@ -2305,6 +2324,7 @@ static void layout_sections(struct module *mod, struct load_info *info) * finder in the two loops below */ { SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL }, { SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL }, + { SHF_RO_AFTER_INIT | SHF_ALLOC, ARCH_SHF_SMALL }, { SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL }, { ARCH_SHF_SMALL | SHF_ALLOC, 0 } }; @@ -2336,7 +2356,11 @@ static void layout_sections(struct module *mod, struct load_info *info) mod->core_layout.size = debug_align(mod->core_layout.size); mod->core_layout.ro_size = mod->core_layout.size; break; - case 3: /* whole core */ + case 2: /* RO after init */ + mod->core_layout.size = debug_align(mod->core_layout.size); + mod->core_layout.ro_after_init_size = mod->core_layout.size; + break; + case 4: /* whole core */ mod->core_layout.size = debug_align(mod->core_layout.size); break; } @@ -2366,7 +2390,14 @@ static void layout_sections(struct module *mod, struct load_info *info) mod->init_layout.size = debug_align(mod->init_layout.size); mod->init_layout.ro_size = mod->init_layout.size; break; - case 3: /* whole init */ + case 2: + /* + * RO after init doesn't apply to init_layout (only + * core_layout), so it just takes the value of ro_size. + */ + mod->init_layout.ro_after_init_size = mod->init_layout.ro_size; + break; + case 4: /* whole init */ mod->init_layout.size = debug_align(mod->init_layout.size); break; } @@ -3193,6 +3224,7 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) { /* Module within temporary copy. */ struct module *mod; + unsigned int ndx; int err; mod = setup_load_info(info, flags); @@ -3215,6 +3247,15 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) /* We will do a special allocation for per-cpu sections later. */ info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; + /* + * Mark ro_after_init section with SHF_RO_AFTER_INIT so that + * layout_sections() can put it in the right place. + * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. + */ + ndx = find_sec(info, ".data..ro_after_init"); + if (ndx) + info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; + /* Determine total sizes, and put offsets in sh_entsize. For now this is done generically; there doesn't appear to be any special cases for the architectures. */ @@ -3381,12 +3422,14 @@ static noinline int do_init_module(struct module *mod) /* Switch to core kallsyms now init is done: kallsyms may be walking! */ rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms); #endif + module_enable_ro(mod, true); mod_tree_remove_init(mod); disable_ro_nx(&mod->init_layout); module_arch_freeing_init(mod); mod->init_layout.base = NULL; mod->init_layout.size = 0; mod->init_layout.ro_size = 0; + mod->init_layout.ro_after_init_size = 0; mod->init_layout.text_size = 0; /* * We want to free module_init, but be aware that kallsyms may be @@ -3478,8 +3521,7 @@ static int complete_formation(struct module *mod, struct load_info *info) /* This relies on module_mutex for list integrity. */ module_bug_finalize(info->hdr, info->sechdrs, mod); - /* Set RO and NX regions */ - module_enable_ro(mod); + module_enable_ro(mod, false); module_enable_nx(mod); /* Mark state as coming so strong_try_module_get() ignores us, -- cgit v1.2.3 From 49aadcf1b6f4240751921dad52e86c760d70a5f1 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 27 Jul 2016 23:11:47 -0400 Subject: extable.h: add stddef.h so "NULL" definition is not implicit While not an issue now, eventually we will have independent users of the extable.h file and we will stop sourcing it via module.h header. In testing that pending work, with very sparse builds, characteristic of an "allnoconfig" on various architectures, we can sometimes hit an instance where the very basic standard definitions aren't present, resulting in: include/linux/extable.h:26:9: error: 'NULL' undeclared (first use in this function) To be clear, this isn't a regression, since currently extable.h is only used by module.h -- however, we will need this addition present before we start migrating exception table users off module.h and onto extable.h during the next release cycle. Cc: Rusty Russell Signed-off-by: Paul Gortmaker Signed-off-by: Rusty Russell --- include/linux/extable.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/extable.h b/include/linux/extable.h index 2c71dccd1bc3..7effea4b257d 100644 --- a/include/linux/extable.h +++ b/include/linux/extable.h @@ -1,6 +1,8 @@ #ifndef _LINUX_EXTABLE_H #define _LINUX_EXTABLE_H +#include /* for NULL */ + struct module; struct exception_table_entry; -- cgit v1.2.3