コード例 #1
0
/*
 * Adjust the displacement if the instruction uses the %rip-relative
 * addressing mode.
 * If it does, Return the address of the 32-bit displacement word.
 * If not, return null.
 * Only applicable to 64-bit x86.
 */
static void __kprobes fix_riprel(struct kprobe *p)
{
#ifdef CONFIG_X86_64
	struct insn insn;
	kernel_insn_init(&insn, p->ainsn.insn);

	if (insn_rip_relative(&insn)) {
		s64 newdisp;
		u8 *disp;
		insn_get_displacement(&insn);
		/*
		 * The copied instruction uses the %rip-relative addressing
		 * mode.  Adjust the displacement for the difference between
		 * the original location of this instruction and the location
		 * of the copy that will actually be run.  The tricky bit here
		 * is making sure that the sign extension happens correctly in
		 * this calculation, since we need a signed 32-bit result to
		 * be sign-extended to 64 bits when it's added to the %rip
		 * value and yield the same 64-bit result that the sign-
		 * extension of the original signed 32-bit displacement would
		 * have given.
		 */
		newdisp = (u8 *) p->addr + (s64) insn.displacement.value -
			  (u8 *) p->ainsn.insn;
		BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check.  */
		disp = (u8 *) p->ainsn.insn + insn_offset_displacement(&insn);
		*(s32 *) disp = (s32) newdisp;
	}
#endif
}
コード例 #2
0
ファイル: core.c プロジェクト: ParrotSec/linux-psec
/*
 * Copy an instruction and adjust the displacement if the instruction
 * uses the %rip-relative addressing mode.
 * If it does, Return the address of the 32-bit displacement word.
 * If not, return null.
 * Only applicable to 64-bit x86.
 */
int __copy_instruction(u8 *dest, u8 *src)
{
	struct insn insn;
	kprobe_opcode_t buf[MAX_INSN_SIZE];
	int length;
	unsigned long recovered_insn =
		recover_probed_instruction(buf, (unsigned long)src);

	if (!recovered_insn)
		return 0;
	kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
	insn_get_length(&insn);
	length = insn.length;

	/* Another subsystem puts a breakpoint, failed to recover */
	if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
		return 0;
	pax_open_kernel();
	memcpy(dest, insn.kaddr, length);
	pax_close_kernel();

#ifdef CONFIG_X86_64
	if (insn_rip_relative(&insn)) {
		s64 newdisp;
		u8 *disp;
		kernel_insn_init(&insn, dest, length);
		insn_get_displacement(&insn);
		/*
		 * The copied instruction uses the %rip-relative addressing
		 * mode.  Adjust the displacement for the difference between
		 * the original location of this instruction and the location
		 * of the copy that will actually be run.  The tricky bit here
		 * is making sure that the sign extension happens correctly in
		 * this calculation, since we need a signed 32-bit result to
		 * be sign-extended to 64 bits when it's added to the %rip
		 * value and yield the same 64-bit result that the sign-
		 * extension of the original signed 32-bit displacement would
		 * have given.
		 */
		newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
		if ((s64) (s32) newdisp != newdisp) {
			pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
			pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value);
			return 0;
		}
		disp = (u8 *) dest + insn_offset_displacement(&insn);
		pax_open_kernel();
		*(s32 *) disp = (s32) newdisp;
		pax_close_kernel();
	}
#endif
	return length;
}
コード例 #3
0
ファイル: core.c プロジェクト: AlexShiLucky/linux
/*
 * Copy an instruction with recovering modified instruction by kprobes
 * and adjust the displacement if the instruction uses the %rip-relative
 * addressing mode. Note that since @real will be the final place of copied
 * instruction, displacement must be adjust by @real, not @dest.
 * This returns the length of copied instruction, or 0 if it has an error.
 */
int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
{
	kprobe_opcode_t buf[MAX_INSN_SIZE];
	unsigned long recovered_insn =
		recover_probed_instruction(buf, (unsigned long)src);

	if (!recovered_insn || !insn)
		return 0;

	/* This can access kernel text if given address is not recovered */
	if (probe_kernel_read(dest, (void *)recovered_insn, MAX_INSN_SIZE))
		return 0;

	kernel_insn_init(insn, dest, MAX_INSN_SIZE);
	insn_get_length(insn);

	/* Another subsystem puts a breakpoint, failed to recover */
	if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
		return 0;

	/* We should not singlestep on the exception masking instructions */
	if (insn_masking_exception(insn))
		return 0;

#ifdef CONFIG_X86_64
	/* Only x86_64 has RIP relative instructions */
	if (insn_rip_relative(insn)) {
		s64 newdisp;
		u8 *disp;
		/*
		 * The copied instruction uses the %rip-relative addressing
		 * mode.  Adjust the displacement for the difference between
		 * the original location of this instruction and the location
		 * of the copy that will actually be run.  The tricky bit here
		 * is making sure that the sign extension happens correctly in
		 * this calculation, since we need a signed 32-bit result to
		 * be sign-extended to 64 bits when it's added to the %rip
		 * value and yield the same 64-bit result that the sign-
		 * extension of the original signed 32-bit displacement would
		 * have given.
		 */
		newdisp = (u8 *) src + (s64) insn->displacement.value
			  - (u8 *) real;
		if ((s64) (s32) newdisp != newdisp) {
			pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
			return 0;
		}
		disp = (u8 *) dest + insn_offset_displacement(insn);
		*(s32 *) disp = (s32) newdisp;
	}
#endif
	return insn->length;
}
コード例 #4
0
ファイル: hijacks.c プロジェクト: cychoi/tpe-lkm
void copy_and_fixup_insn(struct insn *src_insn, void *dest,
	const struct kernsym *func) {

	u32 *to_fixup;
	unsigned long addr;
	BUG_ON(src_insn->length == 0);
	
	memcpy((void *)dest, (const void *)src_insn->kaddr, 
		src_insn->length);
	
	if (src_insn->opcode.bytes[0] == OP_CALL_REL32 ||
	    src_insn->opcode.bytes[0] == OP_JMP_REL32) {
			
		addr = (unsigned long)CODE_ADDR_FROM_OFFSET(
			src_insn->kaddr,
			src_insn->length, 
			src_insn->immediate.value);
		
		if (addr >= (unsigned long)func->addr && 
		    addr < (unsigned long)func->addr + func->size)
			return;
		
		to_fixup = (u32 *)((unsigned long)dest + 
			insn_offset_immediate(src_insn));
		*to_fixup = CODE_OFFSET_FROM_ADDR(dest, src_insn->length,
			(void *)addr);
		return;
	}

#ifdef CONFIG_X86_64
	if (!insn_rip_relative(src_insn))
		return;
		
	addr = (unsigned long)CODE_ADDR_FROM_OFFSET(
		src_insn->kaddr,
		src_insn->length, 
		src_insn->displacement.value);
	
	if (addr >= (unsigned long)func->addr && 
	    addr < (unsigned long)func->addr + func->size)
		return;
	
	to_fixup = (u32 *)((unsigned long)dest + 
		insn_offset_displacement(src_insn));
	*to_fixup = CODE_OFFSET_FROM_ADDR(dest, src_insn->length,
		(void *)addr);
#endif
	return;
}
コード例 #5
0
ファイル: kprobes.c プロジェクト: 12rafael/jellytimekernel
/*
 * Copy an instruction and adjust the displacement if the instruction
 * uses the %rip-relative addressing mode.
 * If it does, Return the address of the 32-bit displacement word.
 * If not, return null.
 * Only applicable to 64-bit x86.
 */
static int __kprobes __copy_instruction(u8 *dest, u8 *src, int recover)
{
	struct insn insn;
	int ret;
	kprobe_opcode_t buf[MAX_INSN_SIZE];

	kernel_insn_init(&insn, src);
	if (recover) {
		insn_get_opcode(&insn);
		if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
			ret = recover_probed_instruction(buf,
							 (unsigned long)src);
			if (ret)
				return 0;
			kernel_insn_init(&insn, buf);
		}
	}
	insn_get_length(&insn);
	memcpy(dest, insn.kaddr, insn.length);

#ifdef CONFIG_X86_64
	if (insn_rip_relative(&insn)) {
		s64 newdisp;
		u8 *disp;
		kernel_insn_init(&insn, dest);
		insn_get_displacement(&insn);
		/*
		 * The copied instruction uses the %rip-relative addressing
		 * mode.  Adjust the displacement for the difference between
		 * the original location of this instruction and the location
		 * of the copy that will actually be run.  The tricky bit here
		 * is making sure that the sign extension happens correctly in
		 * this calculation, since we need a signed 32-bit result to
		 * be sign-extended to 64 bits when it's added to the %rip
		 * value and yield the same 64-bit result that the sign-
		 * extension of the original signed 32-bit displacement would
		 * have given.
		 */
		newdisp = (u8 *) src + (s64) insn.displacement.value -
			  (u8 *) dest;
		BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check.  */
		disp = (u8 *) dest + insn_offset_displacement(&insn);
		*(s32 *) disp = (s32) newdisp;
	}
#endif
	return insn.length;
}
コード例 #6
0
ファイル: uprobes.c プロジェクト: AllenWeb/linux
/*
 * If arch_uprobe->insn doesn't use rip-relative addressing, return
 * immediately.  Otherwise, rewrite the instruction so that it accesses
 * its memory operand indirectly through a scratch register.  Set
 * arch_uprobe->fixups and arch_uprobe->rip_rela_target_address
 * accordingly.  (The contents of the scratch register will be saved
 * before we single-step the modified instruction, and restored
 * afterward.)
 *
 * We do this because a rip-relative instruction can access only a
 * relatively small area (+/- 2 GB from the instruction), and the XOL
 * area typically lies beyond that area.  At least for instructions
 * that store to memory, we can't execute the original instruction
 * and "fix things up" later, because the misdirected store could be
 * disastrous.
 *
 * Some useful facts about rip-relative instructions:
 *
 *  - There's always a modrm byte.
 *  - There's never a SIB byte.
 *  - The displacement is always 4 bytes.
 */
static void
handle_riprel_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
{
	u8 *cursor;
	u8 reg;

	if (mm->context.ia32_compat)
		return;

	auprobe->rip_rela_target_address = 0x0;
	if (!insn_rip_relative(insn))
		return;

	/*
	 * insn_rip_relative() would have decoded rex_prefix, modrm.
	 * Clear REX.b bit (extension of MODRM.rm field):
	 * we want to encode rax/rcx, not r8/r9.
	 */
	if (insn->rex_prefix.nbytes) {
		cursor = auprobe->insn + insn_offset_rex_prefix(insn);
		*cursor &= 0xfe;	/* Clearing REX.B bit */
	}

	/*
	 * Point cursor at the modrm byte.  The next 4 bytes are the
	 * displacement.  Beyond the displacement, for some instructions,
	 * is the immediate operand.
	 */
	cursor = auprobe->insn + insn_offset_modrm(insn);
	insn_get_length(insn);

	/*
	 * Convert from rip-relative addressing to indirect addressing
	 * via a scratch register.  Change the r/m field from 0x5 (%rip)
	 * to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field.
	 */
	reg = MODRM_REG(insn);
	if (reg == 0) {
		/*
		 * The register operand (if any) is either the A register
		 * (%rax, %eax, etc.) or (if the 0x4 bit is set in the
		 * REX prefix) %r8.  In any case, we know the C register
		 * is NOT the register operand, so we use %rcx (register
		 * #1) for the scratch register.
		 */
		auprobe->fixups = UPROBE_FIX_RIP_CX;
		/* Change modrm from 00 000 101 to 00 000 001. */
		*cursor = 0x1;
	} else {
		/* Use %rax (register #0) for the scratch register. */
		auprobe->fixups = UPROBE_FIX_RIP_AX;
		/* Change modrm from 00 xxx 101 to 00 xxx 000 */
		*cursor = (reg << 3);
	}

	/* Target address = address of next instruction + (signed) offset */
	auprobe->rip_rela_target_address = (long)insn->length + insn->displacement.value;

	/* Displacement field is gone; slide immediate field (if any) over. */
	if (insn->immediate.nbytes) {
		cursor++;
		memmove(cursor, cursor + insn->displacement.nbytes, insn->immediate.nbytes);
	}
	return;
}