193 lines
6.1 KiB
C
193 lines
6.1 KiB
C
#include <linux/task_work.h>
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#include <linux/sched.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/atomic.h>
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#include <linux/ipc_namespace.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/kallsyms.h>
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#include <linux/kprobes.h>
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#include <linux/version.h>
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#include <linux/task_work.h>
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#include "deps.h"
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
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#ifndef CONFIG_KPROBES
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# error "Your kernel does not support KProbes, but this is required to compile binder as a kernel module on kernel 5.7 and later"
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#endif
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typedef unsigned long (*kallsyms_lookup_name_t)(const char *name);
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static int dummy_kprobe_handler(struct kprobe *p, struct pt_regs *regs)
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{
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return 0;
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}
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static kallsyms_lookup_name_t get_kallsyms_lookup_name_ptr(void)
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{
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struct kprobe probe;
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int ret;
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kallsyms_lookup_name_t addr;
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memset(&probe, 0, sizeof(probe));
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probe.pre_handler = dummy_kprobe_handler;
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probe.symbol_name = "kallsyms_lookup_name";
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ret = register_kprobe(&probe);
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if (ret)
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return NULL;
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addr = (kallsyms_lookup_name_t) probe.addr;
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unregister_kprobe(&probe);
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return addr;
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}
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#endif
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/*
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* On kernel 5.7 and later, kallsyms_lookup_name() can no longer be called from a kernel
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* module for reasons described here: https://lwn.net/Articles/813350/
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* As binder really needs to use kallsysms_lookup_name() to access some kernel
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* functions that otherwise wouldn't be accessible, KProbes are used on later
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* kernels to get the address of kallsysms_lookup_name(). The function is
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* afterwards used just as before. This is a very dirty hack though and the much
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* better solution would be if all the functions that are currently resolved
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* with kallsysms_lookup_name() would get an EXPORT_SYMBOL() annotation to
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* make them directly accessible to kernel modules.
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*/
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static unsigned long kallsyms_lookup_name_wrapper(const char *name)
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{
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,7,0))
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static kallsyms_lookup_name_t func_ptr = NULL;
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if (!func_ptr)
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func_ptr = get_kallsyms_lookup_name_ptr();
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return func_ptr(name);
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#else
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return kallsyms_lookup_name(name);
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#endif
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}
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,19,0))
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static struct file *(*close_fd_get_file_ptr)(unsigned int fd)
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#else
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static int (*close_fd_get_file_ptr)(unsigned int fd, struct file **res)
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#endif
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= NULL;
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,19,0))
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struct file *close_fd_get_file(unsigned int fd)
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#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(5,11,0))
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int close_fd_get_file(unsigned int fd, struct file **res)
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#else
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int __close_fd_get_file(unsigned int fd, struct file **res)
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#endif
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{
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if (!close_fd_get_file_ptr)
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,11,0))
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close_fd_get_file_ptr = kallsyms_lookup_name_wrapper("close_fd_get_file");
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#else
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close_fd_get_file_ptr = kallsyms_lookup_name_wrapper("__close_fd_get_file");
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#endif
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#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,19,0))
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return close_fd_get_file_ptr(fd);
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#else
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return close_fd_get_file_ptr(fd, res);
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#endif
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}
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static int (*can_nice_ptr)(const struct task_struct *, const int) = NULL;
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int can_nice(const struct task_struct *p, const int nice)
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{
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if (!can_nice_ptr)
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can_nice_ptr = kallsyms_lookup_name_wrapper("can_nice");
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return can_nice_ptr(p, nice);
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}
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static void (*mmput_async_ptr)(struct mm_struct *mm) = NULL;
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void mmput_async(struct mm_struct *mm)
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{
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if (!mmput_async_ptr)
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mmput_async_ptr = kallsyms_lookup_name_wrapper("mmput_async");
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return mmput_async_ptr(mm);
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}
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static int (*security_binder_set_context_mgr_ptr)(struct task_struct *mgr) = NULL;
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int security_binder_set_context_mgr(struct task_struct *mgr)
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{
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if (!security_binder_set_context_mgr_ptr)
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security_binder_set_context_mgr_ptr = kallsyms_lookup_name_wrapper("security_binder_set_context_mgr");
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return security_binder_set_context_mgr_ptr(mgr);
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}
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static int (*security_binder_transaction_ptr)(struct task_struct *from, struct task_struct *to) = NULL;
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int security_binder_transaction(struct task_struct *from, struct task_struct *to)
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{
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if (!security_binder_transaction_ptr)
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security_binder_transaction_ptr = kallsyms_lookup_name_wrapper("security_binder_transaction");
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return security_binder_transaction_ptr(from, to);
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}
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static int (*security_binder_transfer_binder_ptr)(struct task_struct *from, struct task_struct *to) = NULL;
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int security_binder_transfer_binder(struct task_struct *from, struct task_struct *to)
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{
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if (!security_binder_transfer_binder_ptr)
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security_binder_transfer_binder_ptr = kallsyms_lookup_name_wrapper("security_binder_transfer_binder");
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return security_binder_transfer_binder_ptr(from, to);
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}
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static int (*security_binder_transfer_file_ptr)(struct task_struct *from, struct task_struct *to, struct file *file) = NULL;
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int security_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file)
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{
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if (!security_binder_transfer_file_ptr)
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security_binder_transfer_file_ptr = kallsyms_lookup_name_wrapper("security_binder_transfer_file");
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return security_binder_transfer_file_ptr(from, to, file);
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}
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static int (*task_work_add_ptr)(struct task_struct *task, struct callback_head *work,
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enum task_work_notify_mode notify) = NULL;
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int task_work_add(struct task_struct *task, struct callback_head *work,
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enum task_work_notify_mode notify)
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{
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if (!task_work_add_ptr)
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task_work_add_ptr = kallsyms_lookup_name_wrapper("task_work_add");
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return task_work_add_ptr(task, work, notify);
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}
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static void (*zap_page_range_ptr)(struct vm_area_struct *, unsigned long, unsigned long) = NULL;
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void zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned long size)
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{
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if (!zap_page_range_ptr)
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zap_page_range_ptr = kallsyms_lookup_name_wrapper("zap_page_range");
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zap_page_range_ptr(vma, address, size);
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}
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static void (*put_ipc_ns_ptr)(struct ipc_namespace *ns) = NULL;
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void put_ipc_ns(struct ipc_namespace *ns)
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{
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if (!put_ipc_ns_ptr)
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put_ipc_ns_ptr = kallsyms_lookup_name_wrapper("put_ipc_ns");
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put_ipc_ns_ptr(ns);
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}
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static struct ipc_namespace *init_ipc_ns_ptr = NULL;
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struct ipc_namespace *get_init_ipc_ns_ptr(void)
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{
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if (!init_ipc_ns_ptr)
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init_ipc_ns_ptr = kallsyms_lookup_name_wrapper("init_ipc_ns");
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return init_ipc_ns_ptr;
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}
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