[PATCH 4/6] arm64: module: move module randomization to module.c
Mark Rutland
mark.rutland at arm.com
Tue May 9 04:14:49 PDT 2023
When CONFIG_RANDOMIZE_BASE=y, module_alloc_base is a variable which is
configured by kaslr_module_init() in kaslr.c, and otherwise it is an
expression defined in module.h.
As kaslr_module_init() is no longer tightly coupled with the KASLR
initialization code, we can centralize this in module.c.
This patch moves kaslr_module_init() to module.c, making
module_alloc_base a static variable, and removing redundant includes from
kaslr.c. For the defintion of struct arm64_ftr_override we must include
<asm/cpufeature.h>, which was previously included transitively via
another header.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
---
arch/arm64/include/asm/module.h | 6 ----
arch/arm64/kernel/kaslr.c | 60 ++-------------------------------
arch/arm64/kernel/module.c | 48 ++++++++++++++++++++++++++
3 files changed, 50 insertions(+), 64 deletions(-)
diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index 18734fed3bdd7..3e7dcc5fa2f26 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -30,12 +30,6 @@ u64 module_emit_plt_entry(struct module *mod, Elf64_Shdr *sechdrs,
u64 module_emit_veneer_for_adrp(struct module *mod, Elf64_Shdr *sechdrs,
void *loc, u64 val);
-#ifdef CONFIG_RANDOMIZE_BASE
-extern u64 module_alloc_base;
-#else
-#define module_alloc_base ((u64)_etext - MODULES_VSIZE)
-#endif
-
struct plt_entry {
/*
* A program that conforms to the AArch64 Procedure Call Standard
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index ce7079ba1dc1a..17f96a19781d4 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -4,23 +4,12 @@
*/
#include <linux/cache.h>
-#include <linux/crc32.h>
#include <linux/init.h>
-#include <linux/libfdt.h>
-#include <linux/mm_types.h>
-#include <linux/sched.h>
-#include <linux/types.h>
-#include <linux/pgtable.h>
-#include <linux/random.h>
+#include <linux/printk.h>
-#include <asm/fixmap.h>
-#include <asm/kernel-pgtable.h>
+#include <asm/cpufeature.h>
#include <asm/memory.h>
-#include <asm/mmu.h>
-#include <asm/sections.h>
-#include <asm/setup.h>
-u64 __ro_after_init module_alloc_base;
u16 __initdata memstart_offset_seed;
struct arm64_ftr_override kaslr_feature_override __initdata;
@@ -47,48 +36,3 @@ void __init kaslr_init(void)
pr_info("KASLR enabled\n");
__kaslr_is_enabled = true;
}
-
-int kaslr_module_init(void)
-{
- u64 module_range;
- u32 seed;
-
- /*
- * Set a reasonable default for module_alloc_base in case
- * we end up running with module randomization disabled.
- */
- module_alloc_base = (u64)_etext - MODULES_VSIZE;
-
- seed = get_random_u32();
-
- if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) {
- /*
- * Randomize the module region over a 2 GB window covering the
- * kernel. This reduces the risk of modules leaking information
- * about the address of the kernel itself, but results in
- * branches between modules and the core kernel that are
- * resolved via PLTs. (Branches between modules will be
- * resolved normally.)
- */
- module_range = SZ_2G - (u64)(_end - _stext);
- module_alloc_base = max((u64)_end - SZ_2G, (u64)MODULES_VADDR);
- } else {
- /*
- * Randomize the module region by setting module_alloc_base to
- * a PAGE_SIZE multiple in the range [_etext - MODULES_VSIZE,
- * _stext) . This guarantees that the resulting region still
- * covers [_stext, _etext], and that all relative branches can
- * be resolved without veneers unless this region is exhausted
- * and we fall back to a larger 2GB window in module_alloc()
- * when ARM64_MODULE_PLTS is enabled.
- */
- module_range = MODULES_VSIZE - (u64)(_etext - _stext);
- }
-
- /* use the lower 21 bits to randomize the base of the module region */
- module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21;
- module_alloc_base &= PAGE_MASK;
-
- return 0;
-}
-subsys_initcall(kaslr_module_init)
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index b2657ac412261..51fd8abd9b743 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -15,13 +15,61 @@
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/moduleloader.h>
+#include <linux/random.h>
#include <linux/scs.h>
#include <linux/vmalloc.h>
+
#include <asm/alternative.h>
#include <asm/insn.h>
#include <asm/scs.h>
#include <asm/sections.h>
+static u64 __ro_after_init module_alloc_base = (u64)_etext - MODULES_VSIZE;
+
+#ifdef CONFIG_RANDOMIZE_BASE
+static int __init kaslr_module_init(void)
+{
+ u64 module_range;
+ u32 seed;
+
+ if (!kaslr_enabled())
+ return 0;
+
+ seed = get_random_u32();
+
+ if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) {
+ /*
+ * Randomize the module region over a 2 GB window covering the
+ * kernel. This reduces the risk of modules leaking information
+ * about the address of the kernel itself, but results in
+ * branches between modules and the core kernel that are
+ * resolved via PLTs. (Branches between modules will be
+ * resolved normally.)
+ */
+ module_range = SZ_2G - (u64)(_end - _stext);
+ module_alloc_base = max((u64)_end - SZ_2G, (u64)MODULES_VADDR);
+ } else {
+ /*
+ * Randomize the module region by setting module_alloc_base to
+ * a PAGE_SIZE multiple in the range [_etext - MODULES_VSIZE,
+ * _stext) . This guarantees that the resulting region still
+ * covers [_stext, _etext], and that all relative branches can
+ * be resolved without veneers unless this region is exhausted
+ * and we fall back to a larger 2GB window in module_alloc()
+ * when ARM64_MODULE_PLTS is enabled.
+ */
+ module_range = MODULES_VSIZE - (u64)(_etext - _stext);
+ }
+
+ /* use the lower 21 bits to randomize the base of the module region */
+ module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21;
+ module_alloc_base &= PAGE_MASK;
+
+ return 0;
+}
+subsys_initcall(kaslr_module_init)
+#endif
+
void *module_alloc(unsigned long size)
{
u64 module_alloc_end = module_alloc_base + MODULES_VSIZE;
--
2.30.2
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