From 84e1c6bb38eb318e456558b610396d9f1afaabf0 Mon Sep 17 00:00:00 2001 From: matthieu castet Date: Tue, 16 Nov 2010 22:35:16 +0100 Subject: x86: Add RO/NX protection for loadable kernel modules This patch is a logical extension of the protection provided by CONFIG_DEBUG_RODATA to LKMs. The protection is provided by splitting module_core and module_init into three logical parts each and setting appropriate page access permissions for each individual section: 1. Code: RO+X 2. RO data: RO+NX 3. RW data: RW+NX In order to achieve proper protection, layout_sections() have been modified to align each of the three parts mentioned above onto page boundary. Next, the corresponding page access permissions are set right before successful exit from load_module(). Further, free_module() and sys_init_module have been modified to set module_core and module_init as RW+NX right before calling module_free(). By default, the original section layout and access flags are preserved. When compiled with CONFIG_DEBUG_SET_MODULE_RONX=y, the patch will page-align each group of sections to ensure that each page contains only one type of content and will enforce RO/NX for each group of pages. -v1: Initial proof-of-concept patch. -v2: The patch have been re-written to reduce the number of #ifdefs and to make it architecture-agnostic. Code formatting has also been corrected. -v3: Opportunistic RO/NX protection is now unconditional. Section page-alignment is enabled when CONFIG_DEBUG_RODATA=y. -v4: Removed most macros and improved coding style. -v5: Changed page-alignment and RO/NX section size calculation -v6: Fixed comments. Restricted RO/NX enforcement to x86 only -v7: Introduced CONFIG_DEBUG_SET_MODULE_RONX, added calls to set_all_modules_text_rw() and set_all_modules_text_ro() in ftrace -v8: updated for compatibility with linux 2.6.33-rc5 -v9: coding style fixes -v10: more coding style fixes -v11: minor adjustments for -tip -v12: minor adjustments for v2.6.35-rc2-tip -v13: minor adjustments for v2.6.37-rc1-tip Signed-off-by: Siarhei Liakh Signed-off-by: Xuxian Jiang Acked-by: Arjan van de Ven Reviewed-by: James Morris Signed-off-by: H. Peter Anvin Cc: Andi Kleen Cc: Rusty Russell Cc: Stephen Rothwell Cc: Dave Jones Cc: Kees Cook Cc: Linus Torvalds LKML-Reference: <4CE2F914.9070106@free.fr> [ minor cleanliness edits, -v14: build failure fix ] Signed-off-by: Ingo Molnar --- include/linux/module.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index b29e7458b966..ddaa689d71bd 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -308,6 +308,9 @@ struct module /* The size of the executable code in each section. */ unsigned int init_text_size, core_text_size; + /* Size of RO sections of the module (text+rodata) */ + unsigned int init_ro_size, core_ro_size; + /* Arch-specific module values */ struct mod_arch_specific arch; @@ -672,7 +675,6 @@ static inline int module_get_iter_tracepoints(struct tracepoint_iter *iter) { return 0; } - #endif /* CONFIG_MODULES */ #ifdef CONFIG_SYSFS @@ -687,6 +689,13 @@ extern int module_sysfs_initialized; #define __MODULE_STRING(x) __stringify(x) +#ifdef CONFIG_DEBUG_SET_MODULE_RONX +extern void set_all_modules_text_rw(void); +extern void set_all_modules_text_ro(void); +#else +static inline void set_all_modules_text_rw(void) { } +static inline void set_all_modules_text_ro(void) { } +#endif #ifdef CONFIG_GENERIC_BUG void module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *, -- cgit v1.2.3 From dfd62d1d84d83f9421792c78bcf72de9bc2bb603 Mon Sep 17 00:00:00 2001 From: Anders Kaseorg Date: Wed, 24 Nov 2010 15:21:10 -0600 Subject: module: Update prototype for ref_module (formerly use_module) Commit 9bea7f23952d5948f8e5dfdff4de09bb9981fb5f renamed use_module to ref_module (and changed its return value), but forgot to update this prototype in module.h. Signed-off-by: Anders Kaseorg Acked-by: WANG Cong Signed-off-by: Rusty Russell --- include/linux/module.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index b29e7458b966..7575bbbdf2a2 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -517,7 +517,7 @@ static inline void __module_get(struct module *module) #define symbol_put_addr(p) do { } while(0) #endif /* CONFIG_MODULE_UNLOAD */ -int use_module(struct module *a, struct module *b); +int ref_module(struct module *a, struct module *b); /* This is a #define so the string doesn't get put in every .o file */ #define module_name(mod) \ -- cgit v1.2.3 From e94965ed5beb23c6fabf7ed31f625e66d7ff28de Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Wed, 15 Dec 2010 14:00:19 -0800 Subject: module: show version information for built-in modules in sysfs Currently only drivers that are built as modules have their versions shown in /sys/module//version, but this information might also be useful for built-in drivers as well. This especially important for drivers that do not define any parameters - such drivers, if built-in, are completely invisible from userspace. This patch changes MODULE_VERSION() macro so that in case when we are compiling built-in module, version information is stored in a separate section. Kernel then uses this data to create 'version' sysfs attribute in the same fashion it creates attributes for module parameters. Signed-off-by: Dmitry Torokhov Signed-off-by: Rusty Russell --- include/asm-generic/vmlinux.lds.h | 7 +++++ include/linux/module.h | 27 ++++++++++++++++ kernel/params.c | 65 ++++++++++++++++++++++++++++++++------- 3 files changed, 88 insertions(+), 11 deletions(-) (limited to 'include/linux/module.h') diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 68649336c4ad..6ebb81030d2d 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -364,6 +364,13 @@ VMLINUX_SYMBOL(__start___param) = .; \ *(__param) \ VMLINUX_SYMBOL(__stop___param) = .; \ + } \ + \ + /* Built-in module versions. */ \ + __modver : AT(ADDR(__modver) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__start___modver) = .; \ + *(__modver) \ + VMLINUX_SYMBOL(__stop___modver) = .; \ . = ALIGN((align)); \ VMLINUX_SYMBOL(__end_rodata) = .; \ } \ diff --git a/include/linux/module.h b/include/linux/module.h index 8b17fd8c790d..50efcd3ae850 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -58,6 +58,12 @@ struct module_attribute { void (*free)(struct module *); }; +struct module_version_attribute { + struct module_attribute mattr; + const char *module_name; + const char *version; +}; + struct module_kobject { struct kobject kobj; @@ -161,7 +167,28 @@ extern struct module __this_module; Using this automatically adds a checksum of the .c files and the local headers in "srcversion". */ + +#ifdef MODULE #define MODULE_VERSION(_version) MODULE_INFO(version, _version) +#else +#define MODULE_VERSION(_version) \ + extern ssize_t __modver_version_show(struct module_attribute *, \ + struct module *, char *); \ + static struct module_version_attribute __modver_version_attr \ + __used \ + __attribute__ ((__section__ ("__modver"),aligned(sizeof(void *)))) \ + = { \ + .mattr = { \ + .attr = { \ + .name = "version", \ + .mode = S_IRUGO, \ + }, \ + .show = __modver_version_show, \ + }, \ + .module_name = KBUILD_MODNAME, \ + .version = _version, \ + } +#endif /* Optional firmware file (or files) needed by the module * format is simply firmware file name. Multiple firmware diff --git a/kernel/params.c b/kernel/params.c index 08107d181758..0da1411222b9 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -719,9 +719,7 @@ void destroy_params(const struct kernel_param *params, unsigned num) params[i].ops->free(params[i].arg); } -static void __init kernel_add_sysfs_param(const char *name, - struct kernel_param *kparam, - unsigned int name_skip) +static struct module_kobject * __init locate_module_kobject(const char *name) { struct module_kobject *mk; struct kobject *kobj; @@ -729,10 +727,7 @@ static void __init kernel_add_sysfs_param(const char *name, kobj = kset_find_obj(module_kset, name); if (kobj) { - /* We already have one. Remove params so we can add more. */ mk = to_module_kobject(kobj); - /* We need to remove it before adding parameters. */ - sysfs_remove_group(&mk->kobj, &mk->mp->grp); } else { mk = kzalloc(sizeof(struct module_kobject), GFP_KERNEL); BUG_ON(!mk); @@ -743,15 +738,36 @@ static void __init kernel_add_sysfs_param(const char *name, "%s", name); if (err) { kobject_put(&mk->kobj); - printk(KERN_ERR "Module '%s' failed add to sysfs, " - "error number %d\n", name, err); - printk(KERN_ERR "The system will be unstable now.\n"); - return; + printk(KERN_ERR + "Module '%s' failed add to sysfs, error number %d\n", + name, err); + printk(KERN_ERR + "The system will be unstable now.\n"); + return NULL; } - /* So that exit path is even. */ + + /* So that we hold reference in both cases. */ kobject_get(&mk->kobj); } + return mk; +} + +static void __init kernel_add_sysfs_param(const char *name, + struct kernel_param *kparam, + unsigned int name_skip) +{ + struct module_kobject *mk; + int err; + + mk = locate_module_kobject(name); + if (!mk) + return; + + /* We need to remove old parameters before adding more. */ + if (mk->mp) + sysfs_remove_group(&mk->kobj, &mk->mp->grp); + /* These should not fail at boot. */ err = add_sysfs_param(mk, kparam, kparam->name + name_skip); BUG_ON(err); @@ -796,6 +812,32 @@ static void __init param_sysfs_builtin(void) } } +ssize_t __modver_version_show(struct module_attribute *mattr, + struct module *mod, char *buf) +{ + struct module_version_attribute *vattr = + container_of(mattr, struct module_version_attribute, mattr); + + return sprintf(buf, "%s\n", vattr->version); +} + +extern struct module_version_attribute __start___modver[], __stop___modver[]; + +static void __init version_sysfs_builtin(void) +{ + const struct module_version_attribute *vattr; + struct module_kobject *mk; + int err; + + for (vattr = __start___modver; vattr < __stop___modver; vattr++) { + mk = locate_module_kobject(vattr->module_name); + if (mk) { + err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr); + kobject_uevent(&mk->kobj, KOBJ_ADD); + kobject_put(&mk->kobj); + } + } +} /* module-related sysfs stuff */ @@ -875,6 +917,7 @@ static int __init param_sysfs_init(void) } module_sysfs_initialized = 1; + version_sysfs_builtin(); param_sysfs_builtin(); return 0; -- cgit v1.2.3 From 3b90a5b292321b2acac3921f77046ae195aef53f Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 24 Jan 2011 14:32:51 -0600 Subject: module: fix linker error for MODULE_VERSION when !MODULE and CONFIG_SYSFS=n lib/built-in.o:(__modver+0x8): undefined reference to `__modver_version_show' lib/built-in.o:(__modver+0x2c): undefined reference to `__modver_version_show' Simplest to just not emit anything: if they've disabled SYSFS they probably want the smallest kernel possible. Reported-by: Randy Dunlap Signed-off-by: Rusty Russell --- include/linux/module.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index 50efcd3ae850..e7c6385c6683 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -168,7 +168,7 @@ extern struct module __this_module; local headers in "srcversion". */ -#ifdef MODULE +#if defined(MODULE) || !defined(CONFIG_SYSFS) #define MODULE_VERSION(_version) MODULE_INFO(version, _version) #else #define MODULE_VERSION(_version) \ -- cgit v1.2.3