diff --git a/binder/deps.c b/binder/deps.c index cc2da65..6c7a2af 100644 --- a/binder/deps.c +++ b/binder/deps.c @@ -9,11 +9,43 @@ #include #include #include +#include +#include #include #include #include "deps.h" +#ifdef CONFIG_X86_KERNEL_IBT +/* + * With IBT the kernel seals the ENDBR64 of functions it never calls + * indirectly (kallsyms_lookup_name, can_nice, the security_binder_* hooks...), + * so an indirect call to an address looked up here raises #CP (kernel BUG at + * arch/x86/kernel/cet.c). Reach them with push+ret instead, which IBT does + * not track; the callee then returns straight to our caller. + */ +unsigned long binder_ibt_call(void *fn, unsigned long a, unsigned long b, + unsigned long c, unsigned long d); +asm(".pushsection .text\n" + ".type binder_ibt_call, @function\n" + "binder_ibt_call:\n" + " mov %rdi, %r11\n" + " mov %rsi, %rdi\n" + " mov %rdx, %rsi\n" + " mov %rcx, %rdx\n" + " mov %r8, %rcx\n" + " push %r11\n" + " " ASM_RET + ".size binder_ibt_call, .-binder_ibt_call\n" + ".popsection\n"); +STACK_FRAME_NON_STANDARD(binder_ibt_call); +#define IBT_ARGS(a, b, c, d, ...) \ + (unsigned long)(a), (unsigned long)(b), (unsigned long)(c), (unsigned long)(d) +#define deps_call(fn, ...) binder_ibt_call((void *)(fn), IBT_ARGS(__VA_ARGS__, 0, 0, 0, 0)) +#else +#define deps_call(fn, ...) (fn)(__VA_ARGS__) +#endif + #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0)) #ifndef CONFIG_KPROBES @@ -42,20 +74,6 @@ static kallsyms_lookup_name_t get_kallsyms_lookup_name_ptr(void) addr = (kallsyms_lookup_name_t) probe.addr; unregister_kprobe(&probe); -#ifdef CONFIG_X86_KERNEL_IBT - /* - * With IBT, kprobes skip the function's ENDBR64, so probe.addr is 4 - * bytes past the entry. An indirect call there raises #CP; step back. - */ - { - const u8 endbr64[] = { 0xf3, 0x0f, 0x1e, 0xfa }; - u8 *p = (u8 *)addr - sizeof(endbr64); - - if (!memcmp(p, endbr64, sizeof(endbr64))) - addr = (kallsyms_lookup_name_t)p; - } -#endif - return addr; } #endif @@ -78,7 +96,7 @@ static unsigned long kallsyms_lookup_name_wrapper(const char *name) if (!func_ptr) func_ptr = get_kallsyms_lookup_name_ptr(); - return func_ptr(name); + return deps_call(func_ptr, name); #else return kallsyms_lookup_name(name); #endif @@ -111,9 +129,9 @@ int __close_fd_get_file(unsigned int fd, struct file **res) #endif #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,19,0)) - return close_fd_get_file_ptr(fd); + return (struct file *)deps_call(close_fd_get_file_ptr, fd); #else - return close_fd_get_file_ptr(fd, res); + return (int)deps_call(close_fd_get_file_ptr, fd, res); #endif } @@ -123,7 +141,7 @@ int can_nice(const struct task_struct *p, const int nice) { if (!can_nice_ptr) can_nice_ptr = kallsyms_lookup_name_wrapper("can_nice"); - return can_nice_ptr(p, nice); + return (int)deps_call(can_nice_ptr, p, nice); } static void (*mmput_async_ptr)(struct mm_struct *mm) = NULL; @@ -132,7 +150,7 @@ void mmput_async(struct mm_struct *mm) { if (!mmput_async_ptr) mmput_async_ptr = kallsyms_lookup_name_wrapper("mmput_async"); - return mmput_async_ptr(mm); + deps_call(mmput_async_ptr, mm); } static int (*security_binder_set_context_mgr_ptr)(struct task_struct *mgr) = NULL; @@ -141,7 +159,7 @@ int security_binder_set_context_mgr(struct task_struct *mgr) { if (!security_binder_set_context_mgr_ptr) security_binder_set_context_mgr_ptr = kallsyms_lookup_name_wrapper("security_binder_set_context_mgr"); - return security_binder_set_context_mgr_ptr(mgr); + return (int)deps_call(security_binder_set_context_mgr_ptr, mgr); } static int (*security_binder_transaction_ptr)(struct task_struct *from, struct task_struct *to) = NULL; @@ -150,7 +168,7 @@ int security_binder_transaction(struct task_struct *from, struct task_struct *to { if (!security_binder_transaction_ptr) security_binder_transaction_ptr = kallsyms_lookup_name_wrapper("security_binder_transaction"); - return security_binder_transaction_ptr(from, to); + return (int)deps_call(security_binder_transaction_ptr, from, to); } static int (*security_binder_transfer_binder_ptr)(struct task_struct *from, struct task_struct *to) = NULL; @@ -159,7 +177,7 @@ int security_binder_transfer_binder(struct task_struct *from, struct task_struct { if (!security_binder_transfer_binder_ptr) security_binder_transfer_binder_ptr = kallsyms_lookup_name_wrapper("security_binder_transfer_binder"); - return security_binder_transfer_binder_ptr(from, to); + return (int)deps_call(security_binder_transfer_binder_ptr, from, to); } static int (*security_binder_transfer_file_ptr)(struct task_struct *from, struct task_struct *to, struct file *file) = NULL; @@ -168,7 +186,7 @@ int security_binder_transfer_file(struct task_struct *from, struct task_struct * { if (!security_binder_transfer_file_ptr) security_binder_transfer_file_ptr = kallsyms_lookup_name_wrapper("security_binder_transfer_file"); - return security_binder_transfer_file_ptr(from, to, file); + return (int)deps_call(security_binder_transfer_file_ptr, from, to, file); } static int (*task_work_add_ptr)(struct task_struct *task, struct callback_head *work, @@ -179,7 +197,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work, { if (!task_work_add_ptr) task_work_add_ptr = kallsyms_lookup_name_wrapper("task_work_add"); - return task_work_add_ptr(task, work, notify); + return (int)deps_call(task_work_add_ptr, task, work, notify); } #if (LINUX_VERSION_CODE >= KERNEL_VERSION(6,3,0)) @@ -189,7 +207,7 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, un { if (!zap_page_range_single_ptr) zap_page_range_single_ptr = kallsyms_lookup_name_wrapper("zap_page_range_single"); - zap_page_range_single_ptr(vma, address, size, details); + deps_call(zap_page_range_single_ptr, vma, address, size, details); } #else static void (*zap_page_range_ptr)(struct vm_area_struct *, unsigned long, unsigned long) = NULL; @@ -198,7 +216,7 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned { if (!zap_page_range_ptr) zap_page_range_ptr = kallsyms_lookup_name_wrapper("zap_page_range"); - zap_page_range_ptr(vma, address, size); + deps_call(zap_page_range_ptr, vma, address, size); } #endif @@ -208,7 +226,7 @@ void put_ipc_ns(struct ipc_namespace *ns) { if (!put_ipc_ns_ptr) put_ipc_ns_ptr = kallsyms_lookup_name_wrapper("put_ipc_ns"); - put_ipc_ns_ptr(ns); + deps_call(put_ipc_ns_ptr, ns); } static struct ipc_namespace *init_ipc_ns_ptr = NULL;