Re: [PATCH v13 3/8] powerpc/kprobes: Mark newly allocated probes as ROX
From: Christophe Leroy <hidden>
Date: 2021-05-14 05:49:25
Le 10/05/2021 à 03:18, Jordan Niethe a écrit :
quoted hunk ↗ jump to hunk
From: Russell Currey <redacted> Add the arch specific insn page allocator for powerpc. This allocates ROX pages if STRICT_KERNEL_RWX is enabled. These pages are only written to with patch_instruction() which is able to write RO pages. Reviewed-by: Daniel Axtens <redacted> Signed-off-by: Russell Currey <redacted> Signed-off-by: Christophe Leroy <redacted> [jpn: Reword commit message, switch to __vmalloc_node_range()] Signed-off-by: Jordan Niethe <redacted> --- v9: - vmalloc_exec() no longer exists - Set the page to RW before freeing it v10: - use __vmalloc_node_range() v11: - Neaten up v12: - Switch from __vmalloc_node_range() to module_alloc() v13: Use strict_kernel_rwx_enabled() --- arch/powerpc/kernel/kprobes.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 01ab2163659e..b517f3e6e7c5 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c@@ -19,11 +19,13 @@ #include <linux/extable.h> #include <linux/kdebug.h> #include <linux/slab.h> +#include <linux/moduleloader.h> #include <asm/code-patching.h> #include <asm/cacheflush.h> #include <asm/sstep.h> #include <asm/sections.h> #include <asm/inst.h> +#include <asm/set_memory.h> #include <linux/uaccess.h> DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;@@ -103,6 +105,21 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) return addr; } +void *alloc_insn_page(void) +{ + void *page; + + page = module_alloc(PAGE_SIZE); + if (!page) + return NULL; + + if (strict_kernel_rwx_enabled()) {
I'm not sure this is OK. I think we need to make a new helper strict_module_rwx_enabled() because I don't think we want to call that when CONFIG_STRICT_MODULE_RWX is not selected.
+ set_memory_ro((unsigned long)page, 1);
+ set_memory_x((unsigned long)page, 1);
+ }
+ return page;
+}
+
int arch_prepare_kprobe(struct kprobe *p)
{
int ret = 0;