[RFC PATCH v2 05/13] module: Move arch strict rwx support to a separate file

Aaron Tomlin
2022-01-06T23:43:35Z

No functional change.

This patch migrates applicable architecture code
that support strict module rwx from core module code
into kernel/module/arch_strict_rwx.c

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
---
include/linux/module.h | 16 +++++++++++
kernel/module/Makefile | 1 +
kernel/module/arch_strict_rwx.c | 44 ++++++++++++++++++++++++++++
kernel/module/main.c | 51 ---------------------------------
4 files changed, 61 insertions(+), 51 deletions(-)
create mode 100644 kernel/module/arch_strict_rwx.c

diff --git a/include/linux/module.h b/include/linux/module.h
index 8b4d254a84c0..caa7212cf754 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -338,6 +338,22 @@ struct module_layout {
#endif
};

+/*
+ * Modules' sections will be aligned on page boundaries
+ * to ensure complete separation of code and data, but
+ * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y
+ */
+#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
+# define debug_align(X) ALIGN(X, PAGE_SIZE)
+
+extern void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages));
+extern void module_enable_x(const struct module *mod);
+#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+# define debug_align(X) (X)
+
+static void module_enable_x(const struct module *mod) { }
+#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
+
#ifdef CONFIG_MODULES_TREE_LOOKUP
struct mod_tree_root {
struct latch_tree_root root;
diff --git a/kernel/module/Makefile b/kernel/module/Makefile
index 9d593362156d..95fad95a0549 100644
--- a/kernel/module/Makefile
+++ b/kernel/module/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_MODULE_SIG) += signing.o
obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o
obj-$(CONFIG_LIVEPATCH) += livepatch.o
obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
+obj-$(CONFIG_ARCH_HAS_STRICT_MODULE_RWX) += arch_strict_rwx.o
diff --git a/kernel/module/arch_strict_rwx.c b/kernel/module/arch_strict_rwx.c
new file mode 100644
index 000000000000..68e970671ec5
--- /dev/null
+++ b/kernel/module/arch_strict_rwx.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * kernel/module/arch_strict_rwx.c - module arch strict rwx
+ *
+ * Copyright (C) 2015 Rusty Russell
+ */
+
+#include <linux/module.h>
+#include <linux/set_memory.h>
+
+/*
+ * LKM RO/NX protection: protect module's text/ro-data
+ * from modification and any data from execution.
+ *
+ * General layout of module is:
+ * [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)
+ */
+
+/*
+ * Since some arches are moving towards PAGE_KERNEL module allocations instead
+ * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
+ * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
+ * whether we are strict.
+ */
+void frob_text(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->text_size & (PAGE_SIZE-1));
+ set_memory((unsigned long)layout->base,
+ layout->text_size >> PAGE_SHIFT);
+}
+
+void module_enable_x(const struct module *mod)
+{
+ frob_text(&mod->core_layout, set_memory_x);
+ frob_text(&mod->init_layout, set_memory_x);
+}
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 692cc520420d..a0619256b343 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -13,7 +13,6 @@
#include <linux/trace_events.h>
#include <linux/init.h>
#include <linux/kallsyms.h>
-#include <linux/buildid.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
@@ -63,17 +62,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/module.h>

-/*
- * Modules' sections will be aligned on page boundaries
- * to ensure complete separation of code and data, but
- * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y
- */
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
-# define debug_align(X) ALIGN(X, PAGE_SIZE)
-#else
-# define debug_align(X) (X)
-#endif
-
/*
* Mutex protects:
* 1) List of modules (also safely readable with preempt_disable),
@@ -1786,45 +1774,6 @@ static void mod_sysfs_teardown(struct module *mod)
mod_sysfs_fini(mod);
}

-/*
- * LKM RO/NX protection: protect module's text/ro-data
- * from modification and any data from execution.
- *
- * General layout of module is:
- * [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)
- */
-
-/*
- * Since some arches are moving towards PAGE_KERNEL module allocations instead
- * of PAGE_KERNEL_EXEC, keep frob_text() and module_enable_x() outside of the
- * CONFIG_STRICT_MODULE_RWX block below because they are needed regardless of
- * whether we are strict.
- */
-#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX
-static void frob_text(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->text_size & (PAGE_SIZE-1));
- set_memory((unsigned long)layout->base,
- layout->text_size >> PAGE_SHIFT);
-}
-
-static void module_enable_x(const struct module *mod)
-{
- frob_text(&mod->core_layout, set_memory_x);
- frob_text(&mod->init_layout, set_memory_x);
-}
-#else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
-static void module_enable_x(const struct module *mod) { }
-#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */
-
#ifdef CONFIG_STRICT_MODULE_RWX
static void frob_rodata(const struct module_layout *layout,
int (*set_memory)(unsigned long start, int num_pages))
--
2.31.1