| Message ID | 20190821114955.12788-4-maennich@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,01/11] module: support reading multiple values per modinfo tag | expand |
+++ Matthias Maennich [21/08/19 12:49 +0100]: >The EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL() macros can be used to >export a symbol to a specific namespace. There are no _GPL_FUTURE and >_UNUSED variants because these are currently unused, and I'm not sure >they are necessary. > >I didn't add EXPORT_SYMBOL_NS() for ASM exports; this patch sets the >namespace of ASM exports to NULL by default. In case of relative >references, it will be relocatable to NULL. If there's a need, this >should be pretty easy to add. > >A module that wants to use a symbol exported to a namespace must add a >MODULE_IMPORT_NS() statement to their module code; otherwise, modpost >will complain when building the module, and the kernel module loader >will emit an error and fail when loading the module. > >MODULE_IMPORT_NS() adds a modinfo tag 'import_ns' to the module. That >tag can be observed by the modinfo command, modpost and kernel/module.c >at the time of loading the module. > >The ELF symbols are renamed to include the namespace with an asm label; >for example, symbol 'usb_stor_suspend' in namespace USB_STORAGE becomes >'usb_stor_suspend.USB_STORAGE'. This allows modpost to do namespace >checking, without having to go through all the effort of parsing ELF and >relocation records just to get to the struct kernel_symbols. > >On x86_64 I saw no difference in binary size (compression), but at >runtime this will require a word of memory per export to hold the >namespace. An alternative could be to store namespaced symbols in their >own section and use a separate 'struct namespaced_kernel_symbol' for >that section, at the cost of making the module loader more complex. > >Co-developed-by: Martijn Coenen <maco@android.com> >Signed-off-by: Martijn Coenen <maco@android.com> >Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >Signed-off-by: Matthias Maennich <maennich@google.com> >--- > include/asm-generic/export.h | 6 +-- > include/linux/export.h | 85 ++++++++++++++++++++++++++++++------ > include/linux/module.h | 2 + > kernel/module.c | 43 ++++++++++++++++++ > 4 files changed, 120 insertions(+), 16 deletions(-) > >diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h >index 63f54907317b..e2b5d0f569d3 100644 >--- a/include/asm-generic/export.h >+++ b/include/asm-generic/export.h >@@ -17,11 +17,11 @@ > > .macro __put, val, name > #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >- .long \val - ., \name - . >+ .long \val - ., \name - ., 0 - . > #elif defined(CONFIG_64BIT) >- .quad \val, \name >+ .quad \val, \name, 0 > #else >- .long \val, \name >+ .long \val, \name, 0 > #endif > .endm > >diff --git a/include/linux/export.h b/include/linux/export.h >index 28a4d2150689..8e12e05444d1 100644 >--- a/include/linux/export.h >+++ b/include/linux/export.h >@@ -20,6 +20,8 @@ extern struct module __this_module; > > #ifdef CONFIG_MODULES > >+#define NS_SEPARATOR "." >+ > #if defined(__KERNEL__) && !defined(__GENKSYMS__) > #ifdef CONFIG_MODVERSIONS > /* Mark the CRC weak since genksyms apparently decides not to >@@ -49,6 +51,16 @@ extern struct module __this_module; > * absolute relocations that require runtime processing on relocatable > * kernels. > */ >+#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ >+ __ADDRESSABLE(sym) \ >+ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ >+ " .balign 4 \n" \ >+ "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \ >+ " .long " #sym "- . \n" \ >+ " .long __kstrtab_" #sym "- . \n" \ >+ " .long __kstrtab_ns_" #sym "- . \n" \ >+ " .previous \n") >+ > #define __KSYMTAB_ENTRY(sym, sec) \ > __ADDRESSABLE(sym) \ > asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ >@@ -56,32 +68,53 @@ extern struct module __this_module; > "__ksymtab_" #sym ": \n" \ > " .long " #sym "- . \n" \ > " .long __kstrtab_" #sym "- . \n" \ >+ " .long 0 - . \n" \ > " .previous \n") > > struct kernel_symbol { > int value_offset; > int name_offset; >+ int namespace_offset; > }; > #else >+#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ >+ static const struct kernel_symbol __ksymtab_##sym##__##ns \ >+ asm("__ksymtab_" #sym NS_SEPARATOR #ns) \ >+ __attribute__((section("___ksymtab" sec "+" #sym), used)) \ >+ __aligned(sizeof(void *)) \ >+ = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym} Style nit: missing space after __kstrtab_ns_##sym. >+ > #define __KSYMTAB_ENTRY(sym, sec) \ > static const struct kernel_symbol __ksymtab_##sym \ >+ asm("__ksymtab_" #sym) \ > __attribute__((section("___ksymtab" sec "+" #sym), used)) \ > __aligned(sizeof(void *)) \ >- = { (unsigned long)&sym, __kstrtab_##sym } >+ = { (unsigned long)&sym, __kstrtab_##sym, NULL } > > struct kernel_symbol { > unsigned long value; > const char *name; >+ const char *namespace; > }; > #endif > >-/* For every exported symbol, place a struct in the __ksymtab section */ >-#define ___EXPORT_SYMBOL(sym, sec) \ >+#define ___export_symbol_common(sym, sec) \ > extern typeof(sym) sym; \ > __CRC_SYMBOL(sym, sec) \ > static const char __kstrtab_##sym[] \ > __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ >- = #sym; \ >+ = #sym \ Any particular reason for this change? Not that it's important, just noticing the inconsistent inclusion of the semicolon in some of the macros (e.g. __CRC_SYMBOL includes it but __export_symbol_common doesn't). >+ >+/* For every exported symbol, place a struct in the __ksymtab section */ >+#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ >+ ___export_symbol_common(sym, sec); \ >+ static const char __kstrtab_ns_##sym[] \ >+ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ >+ = #ns; \ >+ __KSYMTAB_ENTRY_NS(sym, sec, ns) >+ >+#define ___EXPORT_SYMBOL(sym, sec) \ >+ ___export_symbol_common(sym, sec); \ > __KSYMTAB_ENTRY(sym, sec) > > #if defined(__DISABLE_EXPORTS) >@@ -91,6 +124,7 @@ struct kernel_symbol { > * be reused in other execution contexts such as the UEFI stub or the > * decompressor. > */ >+#define __EXPORT_SYMBOL_NS(sym, sec, ns) > #define __EXPORT_SYMBOL(sym, sec) > > #elif defined(CONFIG_TRIM_UNUSED_KSYMS) >@@ -117,18 +151,26 @@ struct kernel_symbol { > #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) > #define __cond_export_sym_0(sym, sec) /* nothing */ > >+#define __EXPORT_SYMBOL_NS(sym, sec, ns) \ >+ __ksym_marker(sym); \ >+ __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) >+#define __cond_export_ns_sym(sym, sec, ns, conf) \ >+ ___cond_export_ns_sym(sym, sec, ns, conf) >+#define ___cond_export_ns_sym(sym, sec, ns, enabled) \ >+ __cond_export_ns_sym_##enabled(sym, sec, ns) >+#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) >+#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ >+ > #else >+#define __EXPORT_SYMBOL_NS ___EXPORT_SYMBOL_NS > #define __EXPORT_SYMBOL ___EXPORT_SYMBOL > #endif > >-#define EXPORT_SYMBOL(sym) \ >- __EXPORT_SYMBOL(sym, "") >- >-#define EXPORT_SYMBOL_GPL(sym) \ >- __EXPORT_SYMBOL(sym, "_gpl") >- >-#define EXPORT_SYMBOL_GPL_FUTURE(sym) \ >- __EXPORT_SYMBOL(sym, "_gpl_future") >+#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") >+#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") >+#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") >+#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) >+#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) > > #ifdef CONFIG_UNUSED_SYMBOLS > #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") >@@ -138,11 +180,28 @@ struct kernel_symbol { > #define EXPORT_UNUSED_SYMBOL_GPL(sym) > #endif > >-#endif /* __GENKSYMS__ */ >+#endif /* __KERNEL__ && !__GENKSYMS__ */ >+ >+#if defined(__GENKSYMS__) >+/* >+ * When we're running genksyms, ignore the namespace and make the _NS >+ * variants look like the normal ones. There are two reasons for this: >+ * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro >+ * argument is itself not expanded because it's always tokenized or >+ * concatenated; but when running genksyms, a blank definition of the >+ * macro does allow the argument to be expanded; if a namespace >+ * happens to collide with a #define, this can cause issues. >+ * 2) There's no need to modify genksyms to deal with the _NS variants >+ */ >+#define EXPORT_SYMBOL_NS(sym, ns) EXPORT_SYMBOL(sym) >+#define EXPORT_SYMBOL_NS_GPL(sym, ns) EXPORT_SYMBOL_GPL(sym) >+#endif > > #else /* !CONFIG_MODULES... */ > > #define EXPORT_SYMBOL(sym) >+#define EXPORT_SYMBOL_NS(sym, ns) >+#define EXPORT_SYMBOL_NS_GPL(sym, ns) > #define EXPORT_SYMBOL_GPL(sym) > #define EXPORT_SYMBOL_GPL_FUTURE(sym) > #define EXPORT_UNUSED_SYMBOL(sym) >diff --git a/include/linux/module.h b/include/linux/module.h >index 1455812dd325..b3611e749f72 100644 >--- a/include/linux/module.h >+++ b/include/linux/module.h >@@ -280,6 +280,8 @@ struct notifier_block; > > #ifdef CONFIG_MODULES > >+#define MODULE_IMPORT_NS(ns) MODULE_INFO(import_ns, #ns) >+ > extern int modules_disabled; /* for sysctl */ > /* Get/put a kernel symbol (calls must be symmetric) */ > void *__symbol_get(const char *symbol); >diff --git a/kernel/module.c b/kernel/module.c >index a23067907169..57e8253f2251 100644 >--- a/kernel/module.c >+++ b/kernel/module.c >@@ -544,6 +544,15 @@ static const char *kernel_symbol_name(const struct kernel_symbol *sym) > #endif > } > >+static const char *kernel_symbol_namespace(const struct kernel_symbol *sym) >+{ >+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >+ return offset_to_ptr(&sym->namespace_offset); >+#else >+ return sym->namespace; >+#endif >+} >+ > static int cmp_name(const void *va, const void *vb) > { > const char *a; >@@ -1379,6 +1388,34 @@ static inline int same_magic(const char *amagic, const char *bmagic, > } > #endif /* CONFIG_MODVERSIONS */ > >+static char *get_modinfo(const struct load_info *info, const char *tag); >+static char *get_next_modinfo(const struct load_info *info, const char *tag, >+ char *prev); >+ >+static int verify_namespace_is_imported(const struct load_info *info, >+ const struct kernel_symbol *sym, >+ struct module *mod) >+{ >+ const char *namespace; >+ char *imported_namespace; >+ >+ namespace = kernel_symbol_namespace(sym); >+ if (namespace) { >+ imported_namespace = get_modinfo(info, "import_ns"); >+ while (imported_namespace) { >+ if (strcmp(namespace, imported_namespace) == 0) >+ return 0; >+ imported_namespace = get_next_modinfo( >+ info, "import_ns", imported_namespace); >+ } >+ pr_err("%s: module uses symbol (%s) from namespace %s, but does not import it.\n", >+ mod->name, kernel_symbol_name(sym), namespace); >+ return -EINVAL; >+ } >+ return 0; >+} >+ >+ > /* Resolve a symbol for this module. I.e. if we find one, record usage. */ > static const struct kernel_symbol *resolve_symbol(struct module *mod, > const struct load_info *info, >@@ -1413,6 +1450,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, > goto getname; > } > >+ err = verify_namespace_is_imported(info, sym, mod); >+ if (err) { >+ sym = ERR_PTR(err); >+ goto getname; >+ } I think we should verify the namespace before taking a reference to the owner module (just swap the verify_namespace_is_imported() and ref_module() calls here). Other than that, this patch looks good. Thanks! >+ > getname: > /* We must make copy under the lock if we failed to get ref. */ > strncpy(ownername, module_name(owner), MODULE_NAME_LEN); >-- >2.23.0.rc1.153.gdeed80330f-goog >
On Tue, Aug 27, 2019 at 05:37:18PM +0200, Jessica Yu wrote: >+++ Matthias Maennich [21/08/19 12:49 +0100]: >>The EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL() macros can be used to >>export a symbol to a specific namespace. There are no _GPL_FUTURE and >>_UNUSED variants because these are currently unused, and I'm not sure >>they are necessary. >> >>I didn't add EXPORT_SYMBOL_NS() for ASM exports; this patch sets the >>namespace of ASM exports to NULL by default. In case of relative >>references, it will be relocatable to NULL. If there's a need, this >>should be pretty easy to add. >> >>A module that wants to use a symbol exported to a namespace must add a >>MODULE_IMPORT_NS() statement to their module code; otherwise, modpost >>will complain when building the module, and the kernel module loader >>will emit an error and fail when loading the module. >> >>MODULE_IMPORT_NS() adds a modinfo tag 'import_ns' to the module. That >>tag can be observed by the modinfo command, modpost and kernel/module.c >>at the time of loading the module. >> >>The ELF symbols are renamed to include the namespace with an asm label; >>for example, symbol 'usb_stor_suspend' in namespace USB_STORAGE becomes >>'usb_stor_suspend.USB_STORAGE'. This allows modpost to do namespace >>checking, without having to go through all the effort of parsing ELF and >>relocation records just to get to the struct kernel_symbols. >> >>On x86_64 I saw no difference in binary size (compression), but at >>runtime this will require a word of memory per export to hold the >>namespace. An alternative could be to store namespaced symbols in their >>own section and use a separate 'struct namespaced_kernel_symbol' for >>that section, at the cost of making the module loader more complex. >> >>Co-developed-by: Martijn Coenen <maco@android.com> >>Signed-off-by: Martijn Coenen <maco@android.com> >>Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>Signed-off-by: Matthias Maennich <maennich@google.com> >>--- >>include/asm-generic/export.h | 6 +-- >>include/linux/export.h | 85 ++++++++++++++++++++++++++++++------ >>include/linux/module.h | 2 + >>kernel/module.c | 43 ++++++++++++++++++ >>4 files changed, 120 insertions(+), 16 deletions(-) >> >>diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h >>index 63f54907317b..e2b5d0f569d3 100644 >>--- a/include/asm-generic/export.h >>+++ b/include/asm-generic/export.h >>@@ -17,11 +17,11 @@ >> >>.macro __put, val, name >>#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >>- .long \val - ., \name - . >>+ .long \val - ., \name - ., 0 - . >>#elif defined(CONFIG_64BIT) >>- .quad \val, \name >>+ .quad \val, \name, 0 >>#else >>- .long \val, \name >>+ .long \val, \name, 0 >>#endif >>.endm >> >>diff --git a/include/linux/export.h b/include/linux/export.h >>index 28a4d2150689..8e12e05444d1 100644 >>--- a/include/linux/export.h >>+++ b/include/linux/export.h >>@@ -20,6 +20,8 @@ extern struct module __this_module; >> >>#ifdef CONFIG_MODULES >> >>+#define NS_SEPARATOR "." >>+ >>#if defined(__KERNEL__) && !defined(__GENKSYMS__) >>#ifdef CONFIG_MODVERSIONS >>/* Mark the CRC weak since genksyms apparently decides not to >>@@ -49,6 +51,16 @@ extern struct module __this_module; >> * absolute relocations that require runtime processing on relocatable >> * kernels. >> */ >>+#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ >>+ __ADDRESSABLE(sym) \ >>+ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ >>+ " .balign 4 \n" \ >>+ "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \ >>+ " .long " #sym "- . \n" \ >>+ " .long __kstrtab_" #sym "- . \n" \ >>+ " .long __kstrtab_ns_" #sym "- . \n" \ >>+ " .previous \n") >>+ >>#define __KSYMTAB_ENTRY(sym, sec) \ >> __ADDRESSABLE(sym) \ >> asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ >>@@ -56,32 +68,53 @@ extern struct module __this_module; >> "__ksymtab_" #sym ": \n" \ >> " .long " #sym "- . \n" \ >> " .long __kstrtab_" #sym "- . \n" \ >>+ " .long 0 - . \n" \ >> " .previous \n") >> >>struct kernel_symbol { >> int value_offset; >> int name_offset; >>+ int namespace_offset; >>}; >>#else >>+#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ >>+ static const struct kernel_symbol __ksymtab_##sym##__##ns \ >>+ asm("__ksymtab_" #sym NS_SEPARATOR #ns) \ >>+ __attribute__((section("___ksymtab" sec "+" #sym), used)) \ >>+ __aligned(sizeof(void *)) \ >>+ = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym} > >Style nit: missing space after __kstrtab_ns_##sym. > >>+ >>#define __KSYMTAB_ENTRY(sym, sec) \ >> static const struct kernel_symbol __ksymtab_##sym \ >>+ asm("__ksymtab_" #sym) \ >> __attribute__((section("___ksymtab" sec "+" #sym), used)) \ >> __aligned(sizeof(void *)) \ >>- = { (unsigned long)&sym, __kstrtab_##sym } >>+ = { (unsigned long)&sym, __kstrtab_##sym, NULL } >> >>struct kernel_symbol { >> unsigned long value; >> const char *name; >>+ const char *namespace; >>}; >>#endif >> >>-/* For every exported symbol, place a struct in the __ksymtab section */ >>-#define ___EXPORT_SYMBOL(sym, sec) \ >>+#define ___export_symbol_common(sym, sec) \ >> extern typeof(sym) sym; \ >> __CRC_SYMBOL(sym, sec) \ >> static const char __kstrtab_##sym[] \ >> __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ >>- = #sym; \ >>+ = #sym \ > >Any particular reason for this change? Not that it's important, just >noticing the inconsistent inclusion of the semicolon in some of the >macros (e.g. __CRC_SYMBOL includes it but __export_symbol_common doesn't). > I tried to be consistent to let the macro "call site" provide the final semicolon. And you are right, I could have adjusted __CRC_SYMBOL as well. I will adjust this for the next version. >>+ >>+/* For every exported symbol, place a struct in the __ksymtab section */ >>+#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ >>+ ___export_symbol_common(sym, sec); \ >>+ static const char __kstrtab_ns_##sym[] \ >>+ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ >>+ = #ns; \ >>+ __KSYMTAB_ENTRY_NS(sym, sec, ns) >>+ >>+#define ___EXPORT_SYMBOL(sym, sec) \ >>+ ___export_symbol_common(sym, sec); \ >> __KSYMTAB_ENTRY(sym, sec) >> >>#if defined(__DISABLE_EXPORTS) >>@@ -91,6 +124,7 @@ struct kernel_symbol { >> * be reused in other execution contexts such as the UEFI stub or the >> * decompressor. >> */ >>+#define __EXPORT_SYMBOL_NS(sym, sec, ns) >>#define __EXPORT_SYMBOL(sym, sec) >> >>#elif defined(CONFIG_TRIM_UNUSED_KSYMS) >>@@ -117,18 +151,26 @@ struct kernel_symbol { >>#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) >>#define __cond_export_sym_0(sym, sec) /* nothing */ >> >>+#define __EXPORT_SYMBOL_NS(sym, sec, ns) \ >>+ __ksym_marker(sym); \ >>+ __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) >>+#define __cond_export_ns_sym(sym, sec, ns, conf) \ >>+ ___cond_export_ns_sym(sym, sec, ns, conf) >>+#define ___cond_export_ns_sym(sym, sec, ns, enabled) \ >>+ __cond_export_ns_sym_##enabled(sym, sec, ns) >>+#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) >>+#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ >>+ >>#else >>+#define __EXPORT_SYMBOL_NS ___EXPORT_SYMBOL_NS >>#define __EXPORT_SYMBOL ___EXPORT_SYMBOL >>#endif >> >>-#define EXPORT_SYMBOL(sym) \ >>- __EXPORT_SYMBOL(sym, "") >>- >>-#define EXPORT_SYMBOL_GPL(sym) \ >>- __EXPORT_SYMBOL(sym, "_gpl") >>- >>-#define EXPORT_SYMBOL_GPL_FUTURE(sym) \ >>- __EXPORT_SYMBOL(sym, "_gpl_future") >>+#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") >>+#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") >>+#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") >>+#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) >>+#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) >> >>#ifdef CONFIG_UNUSED_SYMBOLS >>#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") >>@@ -138,11 +180,28 @@ struct kernel_symbol { >>#define EXPORT_UNUSED_SYMBOL_GPL(sym) >>#endif >> >>-#endif /* __GENKSYMS__ */ >>+#endif /* __KERNEL__ && !__GENKSYMS__ */ >>+ >>+#if defined(__GENKSYMS__) >>+/* >>+ * When we're running genksyms, ignore the namespace and make the _NS >>+ * variants look like the normal ones. There are two reasons for this: >>+ * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro >>+ * argument is itself not expanded because it's always tokenized or >>+ * concatenated; but when running genksyms, a blank definition of the >>+ * macro does allow the argument to be expanded; if a namespace >>+ * happens to collide with a #define, this can cause issues. >>+ * 2) There's no need to modify genksyms to deal with the _NS variants >>+ */ >>+#define EXPORT_SYMBOL_NS(sym, ns) EXPORT_SYMBOL(sym) >>+#define EXPORT_SYMBOL_NS_GPL(sym, ns) EXPORT_SYMBOL_GPL(sym) >>+#endif >> >>#else /* !CONFIG_MODULES... */ >> >>#define EXPORT_SYMBOL(sym) >>+#define EXPORT_SYMBOL_NS(sym, ns) >>+#define EXPORT_SYMBOL_NS_GPL(sym, ns) >>#define EXPORT_SYMBOL_GPL(sym) >>#define EXPORT_SYMBOL_GPL_FUTURE(sym) >>#define EXPORT_UNUSED_SYMBOL(sym) >>diff --git a/include/linux/module.h b/include/linux/module.h >>index 1455812dd325..b3611e749f72 100644 >>--- a/include/linux/module.h >>+++ b/include/linux/module.h >>@@ -280,6 +280,8 @@ struct notifier_block; >> >>#ifdef CONFIG_MODULES >> >>+#define MODULE_IMPORT_NS(ns) MODULE_INFO(import_ns, #ns) >>+ >>extern int modules_disabled; /* for sysctl */ >>/* Get/put a kernel symbol (calls must be symmetric) */ >>void *__symbol_get(const char *symbol); >>diff --git a/kernel/module.c b/kernel/module.c >>index a23067907169..57e8253f2251 100644 >>--- a/kernel/module.c >>+++ b/kernel/module.c >>@@ -544,6 +544,15 @@ static const char *kernel_symbol_name(const struct kernel_symbol *sym) >>#endif >>} >> >>+static const char *kernel_symbol_namespace(const struct kernel_symbol *sym) >>+{ >>+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS >>+ return offset_to_ptr(&sym->namespace_offset); >>+#else >>+ return sym->namespace; >>+#endif >>+} >>+ >>static int cmp_name(const void *va, const void *vb) >>{ >> const char *a; >>@@ -1379,6 +1388,34 @@ static inline int same_magic(const char *amagic, const char *bmagic, >>} >>#endif /* CONFIG_MODVERSIONS */ >> >>+static char *get_modinfo(const struct load_info *info, const char *tag); >>+static char *get_next_modinfo(const struct load_info *info, const char *tag, >>+ char *prev); >>+ >>+static int verify_namespace_is_imported(const struct load_info *info, >>+ const struct kernel_symbol *sym, >>+ struct module *mod) >>+{ >>+ const char *namespace; >>+ char *imported_namespace; >>+ >>+ namespace = kernel_symbol_namespace(sym); >>+ if (namespace) { >>+ imported_namespace = get_modinfo(info, "import_ns"); >>+ while (imported_namespace) { >>+ if (strcmp(namespace, imported_namespace) == 0) >>+ return 0; >>+ imported_namespace = get_next_modinfo( >>+ info, "import_ns", imported_namespace); >>+ } >>+ pr_err("%s: module uses symbol (%s) from namespace %s, but does not import it.\n", >>+ mod->name, kernel_symbol_name(sym), namespace); >>+ return -EINVAL; >>+ } >>+ return 0; >>+} >>+ >>+ >>/* Resolve a symbol for this module. I.e. if we find one, record usage. */ >>static const struct kernel_symbol *resolve_symbol(struct module *mod, >> const struct load_info *info, >>@@ -1413,6 +1450,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, >> goto getname; >> } >> >>+ err = verify_namespace_is_imported(info, sym, mod); >>+ if (err) { >>+ sym = ERR_PTR(err); >>+ goto getname; >>+ } > >I think we should verify the namespace before taking a reference to >the owner module (just swap the verify_namespace_is_imported() and >ref_module() calls here). > >Other than that, this patch looks good. Thanks! > Thanks! I will address the points above. Cheers, Matthias >>+ >>getname: >> /* We must make copy under the lock if we failed to get ref. */ >> strncpy(ownername, module_name(owner), MODULE_NAME_LEN); >>-- >>2.23.0.rc1.153.gdeed80330f-goog >>
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h index 63f54907317b..e2b5d0f569d3 100644 --- a/include/asm-generic/export.h +++ b/include/asm-generic/export.h @@ -17,11 +17,11 @@ .macro __put, val, name #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS - .long \val - ., \name - . + .long \val - ., \name - ., 0 - . #elif defined(CONFIG_64BIT) - .quad \val, \name + .quad \val, \name, 0 #else - .long \val, \name + .long \val, \name, 0 #endif .endm diff --git a/include/linux/export.h b/include/linux/export.h index 28a4d2150689..8e12e05444d1 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -20,6 +20,8 @@ extern struct module __this_module; #ifdef CONFIG_MODULES +#define NS_SEPARATOR "." + #if defined(__KERNEL__) && !defined(__GENKSYMS__) #ifdef CONFIG_MODVERSIONS /* Mark the CRC weak since genksyms apparently decides not to @@ -49,6 +51,16 @@ extern struct module __this_module; * absolute relocations that require runtime processing on relocatable * kernels. */ +#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ + __ADDRESSABLE(sym) \ + asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ + " .balign 4 \n" \ + "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \ + " .long " #sym "- . \n" \ + " .long __kstrtab_" #sym "- . \n" \ + " .long __kstrtab_ns_" #sym "- . \n" \ + " .previous \n") + #define __KSYMTAB_ENTRY(sym, sec) \ __ADDRESSABLE(sym) \ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ @@ -56,32 +68,53 @@ extern struct module __this_module; "__ksymtab_" #sym ": \n" \ " .long " #sym "- . \n" \ " .long __kstrtab_" #sym "- . \n" \ + " .long 0 - . \n" \ " .previous \n") struct kernel_symbol { int value_offset; int name_offset; + int namespace_offset; }; #else +#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ + static const struct kernel_symbol __ksymtab_##sym##__##ns \ + asm("__ksymtab_" #sym NS_SEPARATOR #ns) \ + __attribute__((section("___ksymtab" sec "+" #sym), used)) \ + __aligned(sizeof(void *)) \ + = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym} + #define __KSYMTAB_ENTRY(sym, sec) \ static const struct kernel_symbol __ksymtab_##sym \ + asm("__ksymtab_" #sym) \ __attribute__((section("___ksymtab" sec "+" #sym), used)) \ __aligned(sizeof(void *)) \ - = { (unsigned long)&sym, __kstrtab_##sym } + = { (unsigned long)&sym, __kstrtab_##sym, NULL } struct kernel_symbol { unsigned long value; const char *name; + const char *namespace; }; #endif -/* For every exported symbol, place a struct in the __ksymtab section */ -#define ___EXPORT_SYMBOL(sym, sec) \ +#define ___export_symbol_common(sym, sec) \ extern typeof(sym) sym; \ __CRC_SYMBOL(sym, sec) \ static const char __kstrtab_##sym[] \ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ - = #sym; \ + = #sym \ + +/* For every exported symbol, place a struct in the __ksymtab section */ +#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ + ___export_symbol_common(sym, sec); \ + static const char __kstrtab_ns_##sym[] \ + __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ + = #ns; \ + __KSYMTAB_ENTRY_NS(sym, sec, ns) + +#define ___EXPORT_SYMBOL(sym, sec) \ + ___export_symbol_common(sym, sec); \ __KSYMTAB_ENTRY(sym, sec) #if defined(__DISABLE_EXPORTS) @@ -91,6 +124,7 @@ struct kernel_symbol { * be reused in other execution contexts such as the UEFI stub or the * decompressor. */ +#define __EXPORT_SYMBOL_NS(sym, sec, ns) #define __EXPORT_SYMBOL(sym, sec) #elif defined(CONFIG_TRIM_UNUSED_KSYMS) @@ -117,18 +151,26 @@ struct kernel_symbol { #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) #define __cond_export_sym_0(sym, sec) /* nothing */ +#define __EXPORT_SYMBOL_NS(sym, sec, ns) \ + __ksym_marker(sym); \ + __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) +#define __cond_export_ns_sym(sym, sec, ns, conf) \ + ___cond_export_ns_sym(sym, sec, ns, conf) +#define ___cond_export_ns_sym(sym, sec, ns, enabled) \ + __cond_export_ns_sym_##enabled(sym, sec, ns) +#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) +#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ + #else +#define __EXPORT_SYMBOL_NS ___EXPORT_SYMBOL_NS #define __EXPORT_SYMBOL ___EXPORT_SYMBOL #endif -#define EXPORT_SYMBOL(sym) \ - __EXPORT_SYMBOL(sym, "") - -#define EXPORT_SYMBOL_GPL(sym) \ - __EXPORT_SYMBOL(sym, "_gpl") - -#define EXPORT_SYMBOL_GPL_FUTURE(sym) \ - __EXPORT_SYMBOL(sym, "_gpl_future") +#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") +#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") +#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") +#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) #ifdef CONFIG_UNUSED_SYMBOLS #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") @@ -138,11 +180,28 @@ struct kernel_symbol { #define EXPORT_UNUSED_SYMBOL_GPL(sym) #endif -#endif /* __GENKSYMS__ */ +#endif /* __KERNEL__ && !__GENKSYMS__ */ + +#if defined(__GENKSYMS__) +/* + * When we're running genksyms, ignore the namespace and make the _NS + * variants look like the normal ones. There are two reasons for this: + * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro + * argument is itself not expanded because it's always tokenized or + * concatenated; but when running genksyms, a blank definition of the + * macro does allow the argument to be expanded; if a namespace + * happens to collide with a #define, this can cause issues. + * 2) There's no need to modify genksyms to deal with the _NS variants + */ +#define EXPORT_SYMBOL_NS(sym, ns) EXPORT_SYMBOL(sym) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) EXPORT_SYMBOL_GPL(sym) +#endif #else /* !CONFIG_MODULES... */ #define EXPORT_SYMBOL(sym) +#define EXPORT_SYMBOL_NS(sym, ns) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) #define EXPORT_SYMBOL_GPL(sym) #define EXPORT_SYMBOL_GPL_FUTURE(sym) #define EXPORT_UNUSED_SYMBOL(sym) diff --git a/include/linux/module.h b/include/linux/module.h index 1455812dd325..b3611e749f72 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -280,6 +280,8 @@ struct notifier_block; #ifdef CONFIG_MODULES +#define MODULE_IMPORT_NS(ns) MODULE_INFO(import_ns, #ns) + extern int modules_disabled; /* for sysctl */ /* Get/put a kernel symbol (calls must be symmetric) */ void *__symbol_get(const char *symbol); diff --git a/kernel/module.c b/kernel/module.c index a23067907169..57e8253f2251 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -544,6 +544,15 @@ static const char *kernel_symbol_name(const struct kernel_symbol *sym) #endif } +static const char *kernel_symbol_namespace(const struct kernel_symbol *sym) +{ +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS + return offset_to_ptr(&sym->namespace_offset); +#else + return sym->namespace; +#endif +} + static int cmp_name(const void *va, const void *vb) { const char *a; @@ -1379,6 +1388,34 @@ static inline int same_magic(const char *amagic, const char *bmagic, } #endif /* CONFIG_MODVERSIONS */ +static char *get_modinfo(const struct load_info *info, const char *tag); +static char *get_next_modinfo(const struct load_info *info, const char *tag, + char *prev); + +static int verify_namespace_is_imported(const struct load_info *info, + const struct kernel_symbol *sym, + struct module *mod) +{ + const char *namespace; + char *imported_namespace; + + namespace = kernel_symbol_namespace(sym); + if (namespace) { + imported_namespace = get_modinfo(info, "import_ns"); + while (imported_namespace) { + if (strcmp(namespace, imported_namespace) == 0) + return 0; + imported_namespace = get_next_modinfo( + info, "import_ns", imported_namespace); + } + pr_err("%s: module uses symbol (%s) from namespace %s, but does not import it.\n", + mod->name, kernel_symbol_name(sym), namespace); + return -EINVAL; + } + return 0; +} + + /* Resolve a symbol for this module. I.e. if we find one, record usage. */ static const struct kernel_symbol *resolve_symbol(struct module *mod, const struct load_info *info, @@ -1413,6 +1450,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, goto getname; } + err = verify_namespace_is_imported(info, sym, mod); + if (err) { + sym = ERR_PTR(err); + goto getname; + } + getname: /* We must make copy under the lock if we failed to get ref. */ strncpy(ownername, module_name(owner), MODULE_NAME_LEN);