DMPATCH/dmpatch.c

   1 /******************************************************************************
   2  * dmpatch.c  ---- patch for device-mapper
   3  *
   4  * Copyright (c) 2021, longpanda <admin@ventoy.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 3 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/kallsyms.h>
  24 #include <linux/mutex.h>
  25 #include <linux/mempool.h>
  26 #include <linux/delay.h>
  27 #include <linux/wait.h>
  28 #include <linux/slab.h>
  29
  30 #define MAX_PATCH   4
  31
  32 #define magic_sig 0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF
  33
  34 typedef int (*kprobe_reg_pf)(void *);
  35 typedef void (*kprobe_unreg_pf)(void *);
  36 typedef int (*printk_pf)(const char *fmt, ...);
  37 typedef int (*set_memory_attr_pf)(unsigned long addr, int numpages);
  38
  39 #pragma pack(1)
  40 typedef struct ko_param
  41 {
  42     unsigned char magic[16];
  43     unsigned long struct_size;
  44     unsigned long pgsize;
  45     unsigned long printk_addr;
  46     unsigned long ro_addr;
  47     unsigned long rw_addr;
  48     unsigned long reg_kprobe_addr;
  49     unsigned long unreg_kprobe_addr;
  50     unsigned long sym_get_addr;
  51     unsigned long sym_get_size;
  52     unsigned long sym_put_addr;
  53     unsigned long sym_put_size;
  54     unsigned long padding[3];
  55 }ko_param;
  56
  57 #pragma pack()
  58
  59 static printk_pf kprintf = NULL;
  60 static set_memory_attr_pf set_mem_ro = NULL;
  61 static set_memory_attr_pf set_mem_rw = NULL;
  62 static kprobe_reg_pf reg_kprobe = NULL;
  63 static kprobe_unreg_pf unreg_kprobe = NULL;
  64
  65 static volatile ko_param g_ko_param =
  66 {
  67     { magic_sig },
  68     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  69 };
  70
  71 #if defined(CONFIG_X86_64)
  72 #define PATCH_OP_POS    3
  73 #define CODE_MATCH(code, i) \
  74     (code[i] == 0x40 && code[i + 1] == 0x80 && code[i + 2] == 0xce && code[i + 3] == 0x80)
  75 #elif defined(CONFIG_X86_32)
  76 #define PATCH_OP_POS    2
  77 #define CODE_MATCH(code, i) \
  78     (code[i] == 0x80 && code[i + 1] == 0xca && code[i + 2] == 0x80 && code[i + 3] == 0xe8)
  79 #else
  80 #error "unsupported arch"
  81 #endif
  82
  83 #define vdebug(fmt, args...) if(kprintf) kprintf(KERN_ERR fmt, ##args)
  84
  85 static unsigned char *g_get_patch[MAX_PATCH] = { NULL };
  86 static unsigned char *g_put_patch[MAX_PATCH] = { NULL };
  87
  88 static void notrace dmpatch_restore_code(unsigned char *opCode)
  89 {
  90     unsigned long align;
  91
  92     if (opCode)
  93     {
  94         align = (unsigned long)opCode / g_ko_param.pgsize * g_ko_param.pgsize;
  95         set_mem_rw(align, 1);
  96         *opCode = 0x80;
  97         set_mem_ro(align, 1);
  98     }
  99 }
 100
 101 static int notrace dmpatch_replace_code
 102 (
 103     unsigned long addr,
 104     unsigned long size,
 105     int expect,
 106     const char *desc,
 107     unsigned char **patch
 108 )
 109 {
 110     int i = 0;
 111     int cnt = 0;
 112     unsigned long align;
 113     unsigned char *opCode = (unsigned char *)addr;
 114
 115     vdebug("patch for %s 0x%lx %d\n", desc, addr, (int)size);
 116
 117     for (i = 0; i < (int)size - 4; i++)
 118     {
 119         if (CODE_MATCH(opCode, i) && cnt < MAX_PATCH)
 120         {
 121             patch[cnt] = opCode + i + PATCH_OP_POS;
 122             cnt++;
 123         }
 124     }
 125
 126     if (cnt != expect || cnt >= MAX_PATCH)
 127     {
 128         vdebug("patch error: cnt=%d expect=%d\n", cnt, expect);
 129         return 1;
 130     }
 131
 132
 133     for (i = 0; i < cnt; i++)
 134     {
 135         opCode = patch[i];
 136         align = (unsigned long)opCode / g_ko_param.pgsize * g_ko_param.pgsize;
 137
 138         set_mem_rw(align, 1);
 139         *opCode = 0;
 140         set_mem_ro(align, 1);
 141     }
 142
 143     return 0;
 144 }
 145
 146 static int notrace dmpatch_init(void)
 147 {
 148     int r = 0;
 149     int rc = 0;
 150
 151     kprintf = (printk_pf)(g_ko_param.printk_addr);
 152
 153     vdebug("dmpatch_init start pagesize=%lu ...\n", g_ko_param.pgsize);
 154
 155     if (g_ko_param.struct_size != sizeof(ko_param))
 156     {
 157         vdebug("Invalid struct size %d %d\n", (int)g_ko_param.struct_size, (int)sizeof(ko_param));
 158         return -EINVAL;
 159     }
 160
 161     if (g_ko_param.sym_get_addr == 0 || g_ko_param.sym_put_addr == 0 ||
 162         g_ko_param.ro_addr == 0 || g_ko_param.rw_addr == 0)
 163     {
 164         return -EINVAL;
 165     }
 166
 167     set_mem_ro = (set_memory_attr_pf)(g_ko_param.ro_addr);
 168     set_mem_rw = (set_memory_attr_pf)(g_ko_param.rw_addr);
 169     reg_kprobe = (kprobe_reg_pf)g_ko_param.reg_kprobe_addr;
 170     unreg_kprobe = (kprobe_unreg_pf)g_ko_param.unreg_kprobe_addr;
 171
 172     r = dmpatch_replace_code(g_ko_param.sym_get_addr, g_ko_param.sym_get_size, 2, "dm_get_table_device", g_get_patch);
 173     if (r)
 174     {
 175         rc = -EINVAL;
 176         goto out;
 177     }
 178     vdebug("patch dm_get_table_device success\n");
 179
 180     r = dmpatch_replace_code(g_ko_param.sym_put_addr, g_ko_param.sym_put_size, 1, "dm_put_table_device", g_put_patch);
 181     if (r)
 182     {
 183         rc = -EINVAL;
 184         goto out;
 185     }
 186     vdebug("patch dm_put_table_device success\n");
 187
 188     vdebug("#####################################\n");
 189     vdebug("######## dm patch success ###########\n");
 190     vdebug("#####################################\n");
 191
 192 out:
 193
 194         return rc;
 195 }
 196
 197 static void notrace dmpatch_exit(void)
 198 {
 199     int i = 0;
 200
 201     for (i = 0; i < MAX_PATCH; i++)
 202     {
 203         dmpatch_restore_code(g_get_patch[i]);
 204         dmpatch_restore_code(g_put_patch[i]);
 205     }
 206
 207     vdebug("dmpatch_exit success\n");
 208 }
 209
 210 module_init(dmpatch_init);
 211 module_exit(dmpatch_exit);
 212
 213
 214 MODULE_DESCRIPTION("dmpatch driver");
 215 MODULE_AUTHOR("longpanda <admin@ventoy.net>");
 216 MODULE_LICENSE("GPL");
 217