diff options
| author | Kevin Brodsky <kevin.brodsky@arm.com> | 2016-11-23 15:41:15 +0000 |
|---|---|---|
| committer | Michael Bestas <mkbestas@lineageos.org> | 2019-12-23 23:43:38 +0200 |
| commit | 1d89066ed9bece01582df8a41a14490cfd04239a (patch) | |
| tree | 23525a31cb84cbe7fb9dd5449035bf4e9a4412ee /arch/arm64/kernel | |
| parent | eb5072c4c72f3fa68280bc726cd69e5ea592d6a5 (diff) | |
FROMLIST: [PATCH v2 3/3] arm64: compat: Add CONFIG_KUSER_HELPERS
(cherry picked from url http://lkml.iu.edu/hypermail/linux/kernel/1709.1/01903.html)
Make it possible to disable the kuser helpers by adding a KUSER_HELPERS
config option (enabled by default). When disabled, all kuser
helpers-related code is removed from the kernel and no mapping is done
at the fixed high address (0xffff0000); any attempt to use a kuser
helper from a 32-bit process will result in a segfault.
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Bug: 9674955
Bug: 63737556
Bug: 20045882
Change-Id: Ie8c543301d39bfe88ef71fb6a669e571914b117b
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/Makefile | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso.c | 10 |
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index f60831160c57..89de53410f3a 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -28,7 +28,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE arm64-obj-$(CONFIG_COMPAT) += sys32.o signal32.o \ sys_compat.o entry32.o arm64-obj-$(CONFIG_COMPAT) += sigreturn32.o -arm64-obj-$(CONFIG_COMPAT) += kuser32.o +arm64-obj-$(CONFIG_KUSER_HELPERS) += kuser32.o arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o arm64-obj-$(CONFIG_ARM64_MODULE_PLTS) += module-plts.o diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 70f465ce58f2..be899757e5fd 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -62,18 +62,22 @@ static const struct vm_special_mapping compat_vdso_spec[] = { .name = "[sigpage]", .pages = &vectors_page[0], }, +#ifdef CONFIG_KUSER_HELPERS { .name = "[kuserhelpers]", .pages = &vectors_page[1], }, +#endif }; static struct page *vectors_page[ARRAY_SIZE(compat_vdso_spec)] __ro_after_init; static int __init alloc_vectors_page(void) { +#ifdef CONFIG_KUSER_HELPERS extern char __kuser_helper_start[], __kuser_helper_end[]; size_t kuser_sz = __kuser_helper_end - __kuser_helper_start; unsigned long kuser_vpage; +#endif extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; size_t sigret_sz = @@ -84,22 +88,26 @@ static int __init alloc_vectors_page(void) if (!sigret_vpage) return -ENOMEM; +#ifdef CONFIG_KUSER_HELPERS kuser_vpage = get_zeroed_page(GFP_ATOMIC); if (!kuser_vpage) { free_page(sigret_vpage); return -ENOMEM; } +#endif /* sigreturn code */ memcpy((void *)sigret_vpage, __aarch32_sigret_code_start, sigret_sz); flush_icache_range(sigret_vpage, sigret_vpage + PAGE_SIZE); vectors_page[0] = virt_to_page(sigret_vpage); +#ifdef CONFIG_KUSER_HELPERS /* kuser helpers */ memcpy((void *)kuser_vpage + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz); flush_icache_range(kuser_vpage, kuser_vpage + PAGE_SIZE); vectors_page[1] = virt_to_page(kuser_vpage); +#endif return 0; } @@ -127,11 +135,13 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp) current->mm->context.vdso = (void *)addr; +#ifdef CONFIG_KUSER_HELPERS /* Map the kuser helpers at the ABI-defined high address. */ ret = _install_special_mapping(mm, AARCH32_KUSER_HELPERS_BASE, PAGE_SIZE, VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC, &compat_vdso_spec[1]); +#endif out: up_write(&mm->mmap_sem); |