/****************************************************************************** * dmpatch.c ---- patch for device-mapper * * Copyright (c) 2021, longpanda * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * */ #include #include #include #include #include #include #include #include #define MAX_PATCH 4 #define magic_sig 0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF typedef int (*kprobe_reg_pf)(void *); typedef void (*kprobe_unreg_pf)(void *); typedef int (*printk_pf)(const char *fmt, ...); typedef int (*set_memory_attr_pf)(unsigned long addr, int numpages); #pragma pack(1) typedef struct ko_param { unsigned char magic[16]; unsigned long struct_size; unsigned long pgsize; unsigned long printk_addr; unsigned long ro_addr; unsigned long rw_addr; unsigned long reg_kprobe_addr; unsigned long unreg_kprobe_addr; unsigned long sym_get_addr; unsigned long sym_get_size; unsigned long sym_put_addr; unsigned long sym_put_size; unsigned long kv_major; unsigned long ibt; unsigned long padding[1]; }ko_param; #pragma pack() static printk_pf kprintf = NULL; static set_memory_attr_pf set_mem_ro = NULL; static set_memory_attr_pf set_mem_rw = NULL; static kprobe_reg_pf reg_kprobe = NULL; static kprobe_unreg_pf unreg_kprobe = NULL; static volatile ko_param g_ko_param = { { magic_sig }, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; #if defined(CONFIG_X86_64) #define PATCH_OP_POS1 3 #define CODE_MATCH1(code, i) \ (code[i] == 0x40 && code[i + 1] == 0x80 && code[i + 2] == 0xce && code[i + 3] == 0x80) #define PATCH_OP_POS2 1 #define CODE_MATCH2(code, i) \ (code[i] == 0x0C && code[i + 1] == 0x80 && code[i + 2] == 0x89 && code[i + 3] == 0xC6) #elif defined(CONFIG_X86_32) #define PATCH_OP_POS1 2 #define CODE_MATCH1(code, i) \ (code[i] == 0x80 && code[i + 1] == 0xca && code[i + 2] == 0x80 && code[i + 3] == 0xe8) #define PATCH_OP_POS2 2 #define CODE_MATCH2(code, i) \ (code[i] == 0x80 && code[i + 1] == 0xca && code[i + 2] == 0x80 && code[i + 3] == 0xe8) #else #error "unsupported arch" #endif #ifdef VTOY_IBT #ifdef CONFIG_X86_64 /* Using 64-bit values saves one instruction clearing the high half of low */ #define DECLARE_ARGS(val, low, high) unsigned long low, high #define EAX_EDX_VAL(val, low, high) ((low) | (high) << 32) #define EAX_EDX_RET(val, low, high) "=a" (low), "=d" (high) #else #define DECLARE_ARGS(val, low, high) unsigned long long val #define EAX_EDX_VAL(val, low, high) (val) #define EAX_EDX_RET(val, low, high) "=A" (val) #endif #define EX_TYPE_WRMSR 8 #define EX_TYPE_RDMSR 9 #define MSR_IA32_S_CET 0x000006a2 /* kernel mode cet */ #define CET_ENDBR_EN (1ULL << 2) /* Exception table entry */ #ifdef __ASSEMBLY__ #define _ASM_EXTABLE_TYPE(from, to, type) \ .pushsection "__ex_table","a" ; \ .balign 4 ; \ .long (from) - . ; \ .long (to) - . ; \ .long type ; \ .popsection #else /* ! __ASSEMBLY__ */ #define _ASM_EXTABLE_TYPE(from, to, type) \ " .pushsection \"__ex_table\",\"a\"\n" \ " .balign 4\n" \ " .long (" #from ") - .\n" \ " .long (" #to ") - .\n" \ " .long " __stringify(type) " \n" \ " .popsection\n" #endif /* __ASSEMBLY__ */ #endif /* VTOY_IBT */ #define vdebug(fmt, args...) if(kprintf) kprintf(KERN_ERR fmt, ##args) static unsigned char *g_get_patch[MAX_PATCH] = { NULL }; static unsigned char *g_put_patch[MAX_PATCH] = { NULL }; static void notrace dmpatch_restore_code(unsigned char *opCode) { unsigned long align; if (opCode) { align = (unsigned long)opCode / g_ko_param.pgsize * g_ko_param.pgsize; set_mem_rw(align, 1); *opCode = 0x80; set_mem_ro(align, 1); } } static int notrace dmpatch_replace_code ( int style, unsigned long addr, unsigned long size, int expect, const char *desc, unsigned char **patch ) { int i = 0; int cnt = 0; unsigned long align; unsigned char *opCode = (unsigned char *)addr; vdebug("patch for %s style[%d] 0x%lx %d\n", desc, style, addr, (int)size); for (i = 0; i < (int)size - 4; i++) { if (style == 1) { if (CODE_MATCH1(opCode, i) && cnt < MAX_PATCH) { patch[cnt] = opCode + i + PATCH_OP_POS1; cnt++; } } else { if (CODE_MATCH2(opCode, i) && cnt < MAX_PATCH) { patch[cnt] = opCode + i + PATCH_OP_POS2; cnt++; } } } if (cnt != expect || cnt >= MAX_PATCH) { vdebug("patch error: cnt=%d expect=%d\n", cnt, expect); return 1; } for (i = 0; i < cnt; i++) { opCode = patch[i]; align = (unsigned long)opCode / g_ko_param.pgsize * g_ko_param.pgsize; set_mem_rw(align, 1); *opCode = 0; set_mem_ro(align, 1); } return 0; } #ifdef VTOY_IBT static __always_inline unsigned long long dmpatch_rdmsr(unsigned int msr) { DECLARE_ARGS(val, low, high); asm volatile("1: rdmsr\n" "2:\n" _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_RDMSR) : EAX_EDX_RET(val, low, high) : "c" (msr)); return EAX_EDX_VAL(val, low, high); } static __always_inline void dmpatch_wrmsr(unsigned int msr, u32 low, u32 high) { asm volatile("1: wrmsr\n" "2:\n" _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_WRMSR) : : "c" (msr), "a"(low), "d" (high) : "memory"); } static u64 dmpatch_ibt_save(void) { u64 msr = 0; u64 val = 0; msr = dmpatch_rdmsr(MSR_IA32_S_CET); val = msr & ~CET_ENDBR_EN; dmpatch_wrmsr(MSR_IA32_S_CET, (u32)(val & 0xffffffffULL), (u32)(val >> 32)); return msr; } static void dmpatch_ibt_restore(u64 save) { u64 msr; msr = dmpatch_rdmsr(MSR_IA32_S_CET); msr &= ~CET_ENDBR_EN; msr |= (save & CET_ENDBR_EN); dmpatch_wrmsr(MSR_IA32_S_CET, (u32)(msr & 0xffffffffULL), (u32)(msr >> 32)); } #else static u64 dmpatch_ibt_save(void) { return 0; } static void dmpatch_ibt_restore(u64 save) { (void)save; } #endif static int notrace dmpatch_init(void) { int r = 0; int rc = 0; u64 msr = 0; if (g_ko_param.ibt == 0x8888) { msr = dmpatch_ibt_save(); } kprintf = (printk_pf)(g_ko_param.printk_addr); vdebug("dmpatch_init start pagesize=%lu ...\n", g_ko_param.pgsize); if (g_ko_param.struct_size != sizeof(ko_param)) { vdebug("Invalid struct size %d %d\n", (int)g_ko_param.struct_size, (int)sizeof(ko_param)); return -EINVAL; } if (g_ko_param.sym_get_addr == 0 || g_ko_param.sym_put_addr == 0 || g_ko_param.ro_addr == 0 || g_ko_param.rw_addr == 0) { return -EINVAL; } set_mem_ro = (set_memory_attr_pf)(g_ko_param.ro_addr); set_mem_rw = (set_memory_attr_pf)(g_ko_param.rw_addr); reg_kprobe = (kprobe_reg_pf)g_ko_param.reg_kprobe_addr; unreg_kprobe = (kprobe_unreg_pf)g_ko_param.unreg_kprobe_addr; r = dmpatch_replace_code(1, g_ko_param.sym_get_addr, g_ko_param.sym_get_size, 2, "dm_get_table_device", g_get_patch); if (r && g_ko_param.kv_major >= 5) { vdebug("new patch dm_get_table_device...\n"); r = dmpatch_replace_code(2, g_ko_param.sym_get_addr, g_ko_param.sym_get_size, 1, "dm_get_table_device", g_get_patch); } if (r) { rc = -EINVAL; goto out; } vdebug("patch dm_get_table_device success\n"); r = dmpatch_replace_code(1, g_ko_param.sym_put_addr, g_ko_param.sym_put_size, 1, "dm_put_table_device", g_put_patch); if (r) { rc = -EINVAL; goto out; } vdebug("patch dm_put_table_device success\n"); vdebug("#####################################\n"); vdebug("######## dm patch success ###########\n"); vdebug("#####################################\n"); if (g_ko_param.ibt == 0x8888) { dmpatch_ibt_restore(msr); } out: return rc; } static void notrace dmpatch_exit(void) { int i = 0; u64 msr; if (g_ko_param.ibt == 0x8888) { msr = dmpatch_ibt_save(); } for (i = 0; i < MAX_PATCH; i++) { dmpatch_restore_code(g_get_patch[i]); dmpatch_restore_code(g_put_patch[i]); } vdebug("dmpatch_exit success\n"); if (g_ko_param.ibt == 0x8888) { dmpatch_ibt_restore(msr); } } module_init(dmpatch_init); module_exit(dmpatch_exit); MODULE_DESCRIPTION("dmpatch driver"); MODULE_AUTHOR("longpanda "); MODULE_LICENSE("GPL");