201 lines
7.3 KiB
C
201 lines
7.3 KiB
C
#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/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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#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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static struct vm_struct *(*get_vm_area_ptr)(unsigned long, unsigned long) = NULL;
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
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static void (*zap_page_range_ptr)(struct vm_area_struct *, unsigned long, unsigned long) = NULL;
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#else
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static void (*zap_page_range_ptr)(struct vm_area_struct *, unsigned long, unsigned long, struct zap_details *) = NULL;
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#endif
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static int (*map_kernel_range_noflush_ptr)(unsigned long start, unsigned long size, pgprot_t prot, struct page **pages) = NULL;
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static void (*unmap_kernel_range_ptr)(unsigned long, unsigned long) = NULL;
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static struct files_struct *(*get_files_struct_ptr)(struct task_struct *) = NULL;
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static void (*put_files_struct_ptr)(struct files_struct *) = NULL;
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static struct sighand_struct *(*__lock_task_sighand_ptr)(struct task_struct *, unsigned long *) = NULL;
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static int (*__alloc_fd_ptr)(struct files_struct *files, unsigned start, unsigned end, unsigned flags) = NULL;
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static void (*__fd_install_ptr)(struct files_struct *files, unsigned int fd, struct file *file) = NULL;
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static int (*__close_fd_ptr)(struct files_struct *files, unsigned int fd) = NULL;
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static int (*can_nice_ptr)(const struct task_struct *, const int) = NULL;
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static int (*security_binder_set_context_mgr_ptr)(struct task_struct *mgr) = NULL;
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static int (*security_binder_transaction_ptr)(struct task_struct *from, struct task_struct *to) = NULL;
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static int (*security_binder_transfer_binder_ptr)(struct task_struct *from, struct task_struct *to) = NULL;
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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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struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
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{
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if (!get_vm_area_ptr)
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get_vm_area_ptr = kallsyms_lookup_name_wrapper("get_vm_area");
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return get_vm_area_ptr(size, flags);
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}
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
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void zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned long size)
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#else
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void zap_page_range(struct vm_area_struct *vma, unsigned long address, unsigned long size, struct zap_details *details)
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#endif
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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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#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
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zap_page_range_ptr(vma, address, size);
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#else
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zap_page_range_ptr(vma, address, size, details);
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#endif
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}
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int map_kernel_range_noflush(unsigned long start, unsigned long size, pgprot_t prot, struct page **pages)
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{
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if (!map_kernel_range_noflush_ptr)
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map_kernel_range_noflush_ptr = kallsyms_lookup_name_wrapper("map_kernel_range_noflush");
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return map_kernel_range_noflush_ptr(start, size, prot, pages);
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}
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void unmap_kernel_range(unsigned long addr, unsigned long size)
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{
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if (!unmap_kernel_range_ptr)
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unmap_kernel_range_ptr = kallsyms_lookup_name_wrapper("unmap_kernel_range");
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unmap_kernel_range_ptr(addr, size);
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}
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struct files_struct *get_files_struct(struct task_struct *task)
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{
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if (!get_files_struct_ptr)
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get_files_struct_ptr = kallsyms_lookup_name_wrapper("get_files_struct");
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return get_files_struct_ptr(task);
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}
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void put_files_struct(struct files_struct *files)
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{
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if (!put_files_struct_ptr)
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put_files_struct_ptr = kallsyms_lookup_name_wrapper("put_files_struct");
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put_files_struct_ptr(files);
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}
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struct sighand_struct *__lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
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{
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if (!__lock_task_sighand_ptr)
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__lock_task_sighand_ptr = kallsyms_lookup_name_wrapper("__lock_task_sighand");
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return __lock_task_sighand_ptr(tsk, flags);
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}
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int __alloc_fd(struct files_struct *files, unsigned start, unsigned end, unsigned flags)
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{
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if (!__alloc_fd_ptr)
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__alloc_fd_ptr = kallsyms_lookup_name_wrapper("__alloc_fd");
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return __alloc_fd_ptr(files, start, end, flags);
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}
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void __fd_install(struct files_struct *files, unsigned int fd, struct file *file)
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{
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if (!__fd_install_ptr)
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__fd_install_ptr = kallsyms_lookup_name_wrapper("__fd_install");
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__fd_install_ptr(files, fd, file);
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}
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int __close_fd(struct files_struct *files, unsigned int fd)
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{
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if (!__close_fd_ptr)
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__close_fd_ptr = kallsyms_lookup_name_wrapper("__close_fd_ptr");
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return __close_fd_ptr(files, fd);
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}
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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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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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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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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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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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