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Ventoy/DMPATCH/dmpatch.c

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/******************************************************************************
* dmpatch.c ---- patch for device-mapper
*
* Copyright (c) 2021, longpanda <admin@ventoy.net>
*
* 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 <http://www.gnu.org/licenses/>.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/mempool.h>
#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/slab.h>
#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)
#define PATCH_OP_POS3 4
#define CODE_MATCH3(code, i) \
(code[i] == 0x44 && code[i + 1] == 0x89 && code[i + 2] == 0xe8 && code[i + 3] == 0x0c && code[i + 4] == 0x80)
#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 PATCH_OP_POS1
#define CODE_MATCH2 CODE_MATCH1
#define PATCH_OP_POS3 PATCH_OP_POS1
#define CODE_MATCH3 CODE_MATCH1
#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 - 8; i++)
{
if (style == 1)
{
if (CODE_MATCH1(opCode, i) && cnt < MAX_PATCH)
{
patch[cnt] = opCode + i + PATCH_OP_POS1;
cnt++;
}
}
else if (style == 2)
{
if (CODE_MATCH2(opCode, i) && cnt < MAX_PATCH)
{
patch[cnt] = opCode + i + PATCH_OP_POS2;
cnt++;
}
}
else if (style == 3)
{
if (CODE_MATCH3(opCode, i) && cnt < MAX_PATCH)
{
patch[cnt] = opCode + i + PATCH_OP_POS3;
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("new2 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 && g_ko_param.kv_major >= 5)
{
vdebug("new3 patch dm_get_table_device...\n");
r = dmpatch_replace_code(3, 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 <admin@ventoy.net>");
MODULE_LICENSE("GPL");
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