@@ -492,7 +492,9 @@ static inline int module_is_live(struct module *mod)
struct module *__module_text_address(unsigned long addr);
struct module *__module_address(unsigned long addr);
+struct module *__module_rodata_address(unsigned long addr);
bool is_module_address(unsigned long addr);
+bool is_module_rodata_address(unsigned long addr);
bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr);
bool is_module_percpu_address(unsigned long addr);
bool is_module_text_address(unsigned long addr);
@@ -646,6 +648,11 @@ static inline struct module *__module_address(unsigned long addr)
return NULL;
}
+static inline struct module *__module_rodata_address(unsigned long addr)
+{
+ return NULL;
+}
+
static inline struct module *__module_text_address(unsigned long addr)
{
return NULL;
@@ -656,6 +663,11 @@ static inline bool is_module_address(unsigned long addr)
return false;
}
+static inline bool is_module_rodata_address(unsigned long addr)
+{
+ return false;
+}
+
static inline bool is_module_percpu_address(unsigned long addr)
{
return false;
@@ -4296,6 +4296,59 @@ struct module *__module_text_address(unsigned long addr)
}
EXPORT_SYMBOL_GPL(__module_text_address);
+/**
+ * is_module_rodata_address - is this address inside read-only module data?
+ * @addr: the address to check.
+ *
+ */
+bool is_module_rodata_address(unsigned long addr)
+{
+ bool ret;
+
+ preempt_disable();
+ ret = __module_rodata_address(addr) != NULL;
+ preempt_enable();
+
+ return ret;
+}
+
+/*
+ * __module_rodata_address - get the module whose rodata/ro_after_init sections
+ * contain the given address.
+ * @addr: the address.
+ *
+ * Must be called with preempt disabled or module mutex held so that
+ * module doesn't get freed during this.
+ */
+struct module *__module_rodata_address(unsigned long addr)
+{
+ struct module *mod = __module_address(addr);
+
+ /*
+ * Make sure module is within the read-only section.
+ * range(base + text_size, base + ro_after_init_size)
+ * encompasses both the rodata and ro_after_init regions.
+ * See comment above frob_text() for the layout diagram.
+ */
+ if (mod) {
+ void *init_base = mod->init_layout.base;
+ unsigned int init_text_size = mod->init_layout.text_size;
+ unsigned int init_ro_after_init_size = mod->init_layout.ro_after_init_size;
+
+ void *core_base = mod->core_layout.base;
+ unsigned int core_text_size = mod->core_layout.text_size;
+ unsigned int core_ro_after_init_size = mod->core_layout.ro_after_init_size;
+
+ if (!within(addr, init_base + init_text_size,
+ init_ro_after_init_size - init_text_size)
+ && !within(addr, core_base + core_text_size,
+ core_ro_after_init_size - core_text_size))
+ mod = NULL;
+ }
+ return mod;
+}
+EXPORT_SYMBOL_GPL(__module_rodata_address);
+
/* Don't grab lock, we're oopsing. */
void print_modules(void)
{
Implement a mechanism to check if a module's address is in the rodata or ro_after_init sections. It mimics the existing functions that test if an address is inside a module's text section. Functions that take a module as an argument will be able to verify that the module address is in a read-only section. The idea is to prevent structures (including modules) that are not read-only from being passed to functions. This implements the first half of a suggestion made by Kees Cook for the Kernel Self Protection Project: - provide mechanism to check for ro_after_init memory areas, and reject structures not marked ro_after_init in vmbus_register() Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Eddie Kovsky <ewk@edkovsky.org> --- Changes in v4: - Rename function __module_ro_address() to __module_rodata_address() - Move module_rodata_address() stub below is_module_address() - Minor comment fixes - Verify that mod is not NULL before setting up layout variables Changes in v3: - Change function name is_module_ro_address() to is_module_rodata_address(). - Improve comments on is_module_rodata_address(). - Add a !CONFIG_MODULES stub for is_module_rodata_address. - Correct and simplify the check for the read-only memory regions in the module address. --- include/linux/module.h | 12 ++++++++++++ kernel/module.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+)