SUPR3HardenedMain-posix.cpp@ 100731

Last change on this file since 100731 was 99739, checked in by vboxsync, 20 months ago
*: doxygen corrections (mostly about removing @returns from functions returning void).
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1	/* $Id: SUPR3HardenedMain-posix.cpp 99739 2023-05-11 01:01:08Z vboxsync $ */
2	/** @file
3	* VirtualBox Support Library - Hardened main(), posix bits.
4	*/
5
6	/*
7	* Copyright (C) 2017-2023 Oracle and/or its affiliates.
8	*
9	* This file is part of VirtualBox base platform packages, as
10	* available from https://www.virtualbox.org.
11	*
12	* This program is free software; you can redistribute it and/or
13	* modify it under the terms of the GNU General Public License
14	* as published by the Free Software Foundation, in version 3 of the
15	* License.
16	*
17	* This program is distributed in the hope that it will be useful, but
18	* WITHOUT ANY WARRANTY; without even the implied warranty of
19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20	* General Public License for more details.
21	*
22	* You should have received a copy of the GNU General Public License
23	* along with this program; if not, see <https://www.gnu.org/licenses>.
24	*
25	* The contents of this file may alternatively be used under the terms
26	* of the Common Development and Distribution License Version 1.0
27	* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28	* in the VirtualBox distribution, in which case the provisions of the
29	* CDDL are applicable instead of those of the GPL.
30	*
31	* You may elect to license modified versions of this file under the
32	* terms and conditions of either the GPL or the CDDL or both.
33	*
34	* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35	*/
36
37
38	/*********************************************************************************************************************************
39	* Header Files *
40	*********************************************************************************************************************************/
41	#include <VBox/err.h>
42	#include <VBox/dis.h>
43	#include <VBox/sup.h>
44
45	#include <iprt/path.h>
46	#include <iprt/string.h>
47	#include <iprt/x86.h>
48
49	#include <dlfcn.h>
50	#include <sys/mman.h>
51	#if defined(RT_OS_SOLARIS)
52	# include <link.h>
53	#endif
54	#include <stdio.h>
55	#include <stdint.h>
56
57	#include "SUPLibInternal.h"
58
59
60	/*********************************************************************************************************************************
61	* Defined Constants And Macros *
62	*********************************************************************************************************************************/
63
64	/**
65	* Memory for code patching.
66	*/
67	#define DLOPEN_PATCH_MEMORY_SIZE _4K
68
69
70	/*********************************************************************************************************************************
71	* Structures and Typedefs *
72	*********************************************************************************************************************************/
73	#ifndef SUP_HARDENED_WITHOUT_DLOPEN_PATCHING
74	/**
75	* Callback (SUPHARDENEDPOSIXHOOK::pfnResolv) for triggering lazy GOT resolver.
76	*
77	* This generally just calls the API in a harmless manner and triggers the lazy
78	* resolving of the symbol, ensuring a proper address in the GOT/PLT entry.
79	*
80	* On Solaris dlsym() will return the value in the GOT/PLT entry. We don't wish
81	* to patch the lazy loader trampoline function, but rather the real function!
82	*/
83	typedef DECLCALLBACKTYPE(void, FNSUPHARDENEDSYMRESOLVE,(void));
84	/** Pointer to FNSUPHARDENEDSYMRESOLVE. */
85	typedef FNSUPHARDENEDSYMRESOLVE *PFNSUPHARDENEDSYMRESOLVE;
86
87	/**
88	* A hook descriptor.
89	*/
90	typedef struct SUPHARDENEDPOSIXHOOK
91	{
92	/** The symbol to hook. */
93	const char *pszSymbol;
94	/** The intercepting wrapper doing additional checks. */
95	PFNRT pfnHook;
96	/** Where to store the pointer to the code into patch memory
97	* which resumes the original call.
98	* @note uintptr_t instead of PFNRT is for Clang 11. */
99	uintptr_t *ppfnRealResume;
100	/** Pointer to the resolver method used on Solaris. */
101	PFNSUPHARDENEDSYMRESOLVE pfnResolve;
102	} SUPHARDENEDPOSIXHOOK;
103	/** Pointer to a hook descriptor. */
104	typedef SUPHARDENEDPOSIXHOOK *PSUPHARDENEDPOSIXHOOK;
105	/** Pointer to a const hook descriptor. */
106	typedef const SUPHARDENEDPOSIXHOOK *PCSUPHARDENEDPOSIXHOOK;
107
108	/** dlopen() declaration. */
109	typedef void FNDLOPEN(const char pszFilename, int fFlags);
110	/** Pointer to dlopen. */
111	typedef FNDLOPEN *PFNDLOPEN;
112
113	#ifdef SUP_HARDENED_WITH_DLMOPEN
114	/** dlmopen() declaration */
115	typedef void FNDLMOPEN(Lmid_t idLm, const char pszFilename, int fFlags);
116	/** Pointer to dlmopen. */
117	typedef FNDLMOPEN *PFNDLMOPEN;
118	#endif
119
120	#endif /* SUP_HARDENED_WITHOUT_DLOPEN_PATCHING */
121
122
123	/*********************************************************************************************************************************
124	* Internal Functions *
125	*********************************************************************************************************************************/
126	#ifndef SUP_HARDENED_WITHOUT_DLOPEN_PATCHING
127	static FNSUPHARDENEDSYMRESOLVE supR3HardenedPosixMonitorDlopenResolve;
128	#ifdef SUP_HARDENED_WITH_DLMOPEN
129	static FNSUPHARDENEDSYMRESOLVE supR3HardenedPosixMonitorDlmopenResolve;
130	#endif
131
132	/* SUPR3HardenedMainA-posix.asm: */
133	DECLASM(void) supR3HardenedPosixMonitor_Dlopen(const char *pszFilename, int fFlags);
134	#ifdef SUP_HARDENED_WITH_DLMOPEN
135	DECLASM(void) supR3HardenedPosixMonitor_Dlmopen(Lmid_t idLm, const char *pszFilename, int fFlags);
136	#endif
137	#endif /* SUP_HARDENED_WITHOUT_DLOPEN_PATCHING */
138
139
140	/*********************************************************************************************************************************
141	* Global Variables *
142	*********************************************************************************************************************************/
143	#ifndef SUP_HARDENED_WITHOUT_DLOPEN_PATCHING
144
145	RT_C_DECLS_BEGIN
146	/** Resume patch for dlopen(), jumped to form assembly stub. */
147	DECL_HIDDEN_DATA(PFNDLOPEN) g_pfnDlopenReal = NULL;
148	#ifdef SUP_HARDENED_WITH_DLMOPEN
149	/** Resume patch for dlmopen(), jumped to form assembly stub. */
150	DECL_HIDDEN_DATA(PFNDLMOPEN) g_pfnDlmopenReal = NULL;
151	#endif
152	RT_C_DECLS_END
153
154	/** Memory allocated for the patches. */
155	static uint8_t *g_pbExecMemory = NULL;
156	/** Offset into the patch memory which is not used. */
157	static uint32_t g_offExecMemory = 0;
158
159	/**
160	* Array of hooks to install.
161	*/
162	static SUPHARDENEDPOSIXHOOK const g_aHooks[] =
163	{
164	/* pszSymbol, pfnHook, ppfnRealResume, pfnResolve */
165	{ "dlopen", (PFNRT)supR3HardenedPosixMonitor_Dlopen, (uintptr_t *)&g_pfnDlopenReal, supR3HardenedPosixMonitorDlopenResolve },
166	#ifdef SUP_HARDENED_WITH_DLMOPEN
167	{ "dlmopen", (PFNRT)supR3HardenedPosixMonitor_Dlmopen, (uintptr_t *)&g_pfnDlmopenReal, supR3HardenedPosixMonitorDlmopenResolve }
168	#endif
169	};
170
171
172
173	/**
174	* Verifies the given library for proper access rights for further loading
175	* into the process.
176	*
177	* @returns Flag whether the access rights of the library look sane and loading
178	* it is not considered a security risk. Returns true if the library
179	* looks sane, false otherwise.
180	* @param pszFilename The library to load, this can be an absolute or relative path
181	* or just the filename of the library when the default paths should
182	* be searched. NULL is allowed too to indicate opening the main
183	* binary.
184	*/
185	DECLASM(bool) supR3HardenedPosixMonitor_VerifyLibrary(const char *pszFilename)
186	{
187	/*
188	* Giving NULL as the filename indicates opening the main program which is fine
189	* We are already loaded and executing after all.
190	*
191	* Filenames without any path component (whether absolute or relative) are allowed
192	* unconditionally too as the loader will only search the default paths configured by root.
193	*/
194	bool fAllow = true;
195
196	if ( pszFilename
197	&& strchr(pszFilename, '/') != NULL)
198	{
199	#if defined(RT_OS_LINUX)
200	int rc = supR3HardenedVerifyFileFollowSymlinks(pszFilename, RTHCUINTPTR_MAX, true /* fMaybe3rdParty */,
201	NULL /* pErrInfo */);
202	#else
203	int rc = supR3HardenedVerifyFile(pszFilename, RTHCUINTPTR_MAX, true /* fMaybe3rdParty */,
204	NULL /* pErrInfo */);
205	#endif
206
207	if (RT_FAILURE(rc))
208	fAllow = false;
209	}
210
211	return fAllow;
212	}
213
214
215	/**
216	* Returns the start address of the given symbol if found or NULL otherwise.
217	*
218	* @returns Start address of the symbol or NULL if not found.
219	* @param pszSymbol The symbol name.
220	* @param pfnResolve The resolver to call before trying to query the start address.
221	*/
222	static void supR3HardenedMainPosixGetStartBySymbol(const char pszSymbol, PFNSUPHARDENEDSYMRESOLVE pfnResolve)
223	{
224	#ifndef RT_OS_SOLARIS
225	RT_NOREF(pfnResolve);
226	return dlsym(RTLD_DEFAULT, pszSymbol);
227
228	#else /* RT_OS_SOLARIS */
229	/*
230	* Solaris is tricky as dlsym doesn't return the actual start address of
231	* the symbol but the start of the trampoline in the PLT of the caller.
232	*
233	* Disassemble the first jmp instruction to get at the entry in the global
234	* offset table where the actual address is stored.
235	*
236	* To counter lazy symbol resolving, we first have to call the API before
237	* trying to resolve and disassemble it.
238	*/
239	pfnResolve();
240
241	uint8_t pbSym = (uint8_t )dlsym(RTLD_DEFAULT, pszSymbol);
242
243	# ifdef RT_ARCH_AMD64
244	DISSTATE Dis;
245	uint32_t cbInstr = 1;
246	int rc = DISInstr(pbSym, DISCPUMODE_64BIT, &Dis, &cbInstr);
247	if ( RT_FAILURE(rc)
248	\|\| Dis.pCurInstr->uOpcode != OP_JMP
249	\|\| !(Dis.arch.x86.ModRM.Bits.Mod == 0 && Dis.arch.x86.ModRM.Bits.Rm == 5 /* wrt RIP */))
250	return NULL;
251
252	/* Extract start address. */
253	pbSym = (pbSym + cbInstr + Dis.Param1.arch.x86.uDisp.i32);
254	pbSym = (uint8_t )((uintptr_t *)pbSym);
255	# else
256	# error "Unsupported architecture"
257	# endif
258
259	return pbSym;
260	#endif /* RT_OS_SOLARIS */
261	}
262
263
264	/**
265	* Allocates executable patch memory with the given constraints.
266	*
267	* @returns VBox status code.
268	* @param cb Size of the patch memory in bytes.
269	* @param pvHint Where to try allocating nearby.
270	* @param fRipRelAddr Flag whether the executable memory must be within
271	* 2GB before or after the hint as it will contain
272	* instructions using RIP relative addressing
273	*/
274	static uint8_t supR3HardenedMainPosixExecMemAlloc(size_t cb, void pvHint, bool fRipRelAddr)
275	{
276	AssertReturn(cb < _1K, NULL);
277
278	/* Lazy allocation of exectuable memory. */
279	if (!g_pbExecMemory)
280	{
281	g_pbExecMemory = (uint8_t *)mmap(pvHint, DLOPEN_PATCH_MEMORY_SIZE, PROT_READ \| PROT_WRITE \| PROT_EXEC,
282	MAP_SHARED \| MAP_ANONYMOUS, -1, 0);
283	g_offExecMemory = 0;
284	if (g_pbExecMemory == MAP_FAILED)
285	return NULL;
286
287	memset(g_pbExecMemory, 0xcc, DLOPEN_PATCH_MEMORY_SIZE);
288	}
289
290	if (g_offExecMemory + cb >= DLOPEN_PATCH_MEMORY_SIZE)
291	return NULL;
292
293	uint8_t *pb = &g_pbExecMemory[g_offExecMemory];
294
295	if (fRipRelAddr)
296	{
297	/* Check that we allocated within 2GB of the hint. */
298	uintptr_t uPtrHint = (uintptr_t)pvHint;
299	uintptr_t uPtrPatchMem = (uintptr_t)pb;
300	uintptr_t cbDistance = uPtrHint < uPtrPatchMem
301	? uPtrPatchMem - uPtrHint
302	: uPtrHint - uPtrPatchMem;
303
304	if (cbDistance >= _2G - _4K)
305	return NULL;
306	}
307
308	g_offExecMemory = RT_ALIGN_32(g_offExecMemory + cb, 16);
309	return pb;
310	}
311
312
313	/**
314	* Hooks the given method to execute the given one first.
315	*
316	* @returns VBox status code.
317	* @param pszSymbol The symbol to hook.
318	* @param pfnHook The hook to install.
319	* @param ppfnReal Where to store the pointer to entry point of the real method
320	* (somewhere in patch memory).
321	* @param pfnResolve The resolver to call before trying to query the start address.
322	*/
323	static int supR3HardenedMainPosixHookOne(const char pszSymbol, PFNRT pfnHook, uintptr_t /PFNRT/ ppfnReal,
324	PFNSUPHARDENEDSYMRESOLVE pfnResolve)
325	{
326	void *pfnTarget = supR3HardenedMainPosixGetStartBySymbol(pszSymbol, pfnResolve);
327	if (!pfnTarget)
328	return VERR_NOT_FOUND;
329
330	/*
331	* Make the target memory writeable to be able to insert the patch.
332	* Unprotect two pages in case the code crosses a page boundary.
333	*/
334	void pvTargetBase = (void )(((uintptr_t)pfnTarget) & ~(uintptr_t)(_4K - 1));
335	int rcPsx = mprotect(pvTargetBase, 2 * _4K, PROT_WRITE \| PROT_READ \| PROT_EXEC);
336	if (rcPsx == -1)
337	return VERR_SUPLIB_TEXT_NOT_WRITEABLE;
338
339	uint8_t * const pbTarget = (uint8_t *)(uintptr_t)pfnTarget;
340
341	DISSTATE Dis;
342	uint32_t cbInstr;
343	uint32_t offJmpBack = 0;
344	uint32_t cbPatchMem = 0;
345
346	#ifdef RT_ARCH_AMD64
347	/*
348	* Patch 64-bit hosts.
349	*/
350	uint32_t cRipRelMovs = 0;
351	uint32_t cRelCalls = 0;
352
353	/* Just use the disassembler to skip 12 bytes or more, we might need to
354	rewrite mov instructions using RIP relative addressing. */
355	while (offJmpBack < 12)
356	{
357	cbInstr = 1;
358	int rc = DISInstr(pbTarget + offJmpBack, DISCPUMODE_64BIT, &Dis, &cbInstr);
359	if ( RT_FAILURE(rc)
360	\|\| ( Dis.pCurInstr->fOpType & DISOPTYPE_CONTROLFLOW
361	&& Dis.pCurInstr->uOpcode != OP_CALL)
362	\|\| ( Dis.arch.x86.ModRM.Bits.Mod == 0
363	&& Dis.arch.x86.ModRM.Bits.Rm == 5 /* wrt RIP */
364	&& Dis.pCurInstr->uOpcode != OP_MOV))
365	return VERR_SUPLIB_UNEXPECTED_INSTRUCTION;
366
367	if (Dis.arch.x86.ModRM.Bits.Mod == 0 && Dis.arch.x86.ModRM.Bits.Rm == 5 /* wrt RIP */)
368	cRipRelMovs++;
369	if ( Dis.pCurInstr->uOpcode == OP_CALL
370	&& (Dis.pCurInstr->fOpType & DISOPTYPE_RELATIVE_CONTROLFLOW))
371	cRelCalls++;
372
373	offJmpBack += cbInstr;
374	cbPatchMem += cbInstr;
375	}
376
377	/*
378	* Each relative call requires extra bytes as it is converted to a pushq imm32
379	* + mov [RSP+4], imm32 + a jmp qword [$+8 wrt RIP] to avoid clobbering registers.
380	*/
381	cbPatchMem += cRelCalls * RT_ALIGN_32(13 + 6 + 8, 8);
382	cbPatchMem += 14; /* jmp qword [$+8 wrt RIP] + 8 byte address to jump to. */
383	cbPatchMem = RT_ALIGN_32(cbPatchMem, 8);
384
385	/* Allocate suitable executable memory available. */
386	bool fConvRipRelMovs = false;
387	uint8_t *pbPatchMem = supR3HardenedMainPosixExecMemAlloc(cbPatchMem, pbTarget, cRipRelMovs > 0);
388	if (!pbPatchMem)
389	{
390	/*
391	* Try to allocate memory again without the RIP relative mov addressing constraint
392	* Makes it a bit more difficult for us later on but there is no way around it.
393	* We need to increase the patch memory because we create two instructions for one
394	* (7 bytes for the RIP relative mov vs. 13 bytes for the two instructions replacing it ->
395	* need to allocate 6 bytes more per RIP relative mov).
396	*/
397	fConvRipRelMovs = true;
398	if (cRipRelMovs > 0)
399	pbPatchMem = supR3HardenedMainPosixExecMemAlloc(cbPatchMem + cRipRelMovs * 6,
400	pbTarget, false /fRipRelAddr/);
401
402	if (!pbPatchMem)
403	return VERR_NO_MEMORY;
404	}
405
406	/* Assemble the code for resuming the call.*/
407	*ppfnReal = (uintptr_t)pbPatchMem;
408
409	/* Go through the instructions to patch and fixup any rip relative mov instructions. */
410	uint32_t offInsn = 0;
411	while (offInsn < offJmpBack)
412	{
413	cbInstr = 1;
414	int rc = DISInstr(pbTarget + offInsn, DISCPUMODE_64BIT, &Dis, &cbInstr);
415	if ( RT_FAILURE(rc)
416	\|\| ( Dis.pCurInstr->fOpType & DISOPTYPE_CONTROLFLOW
417	&& Dis.pCurInstr->uOpcode != OP_CALL))
418	return VERR_SUPLIB_UNEXPECTED_INSTRUCTION;
419
420	if ( Dis.arch.x86.ModRM.Bits.Mod == 0
421	&& Dis.arch.x86.ModRM.Bits.Rm == 5 /* wrt RIP */
422	&& Dis.pCurInstr->uOpcode == OP_MOV)
423	{
424	/* Deduce destination register and write out new instruction. */
425	if (RT_UNLIKELY(!( (Dis.Param1.fUse & (DISUSE_BASE \| DISUSE_REG_GEN64))
426	&& (Dis.Param2.fUse & DISUSE_RIPDISPLACEMENT32))))
427	return VERR_SUPLIB_UNEXPECTED_INSTRUCTION;
428
429	uintptr_t uAddr = (uintptr_t)&pbTarget[offInsn + cbInstr] + (intptr_t)Dis.Param2.arch.x86.uDisp.i32;
430
431	if (fConvRipRelMovs)
432	{
433	/*
434	* Create two instructions, first one moves the address as a constant to the destination register
435	* and the second one loads the data from the memory into the destination register.
436	*/
437
438	*pbPatchMem++ = 0x48;
439	*pbPatchMem++ = 0xb8 + Dis.Param1.arch.x86.Base.idxGenReg;
440	(uintptr_t )pbPatchMem = uAddr;
441	pbPatchMem += sizeof(uintptr_t);
442
443	*pbPatchMem++ = 0x48;
444	*pbPatchMem++ = 0x8b;
445	*pbPatchMem++ = (Dis.Param1.arch.x86.Base.idxGenReg << X86_MODRM_REG_SHIFT) \| Dis.Param1.arch.x86.Base.idxGenReg;
446	}
447	else
448	{
449	intptr_t iDispNew = uAddr - (uintptr_t)&pbPatchMem[3 + sizeof(int32_t)];
450	Assert(iDispNew == (int32_t)iDispNew);
451
452	/* Assemble the mov to register instruction with the updated rip relative displacement. */
453	*pbPatchMem++ = 0x48;
454	*pbPatchMem++ = 0x8b;
455	*pbPatchMem++ = (Dis.Param1.arch.x86.Base.idxGenReg << X86_MODRM_REG_SHIFT) \| 5;
456	(int32_t )pbPatchMem = (int32_t)iDispNew;
457	pbPatchMem += sizeof(int32_t);
458	}
459	}
460	else if ( Dis.pCurInstr->uOpcode == OP_CALL
461	&& (Dis.pCurInstr->fOpType & DISOPTYPE_RELATIVE_CONTROLFLOW))
462	{
463	/* Convert to absolute jump. */
464	uintptr_t uAddr = (uintptr_t)&pbTarget[offInsn + cbInstr] + (intptr_t)Dis.Param1.uValue;
465
466	/* Skip the push instructions till the return address is known. */
467	uint8_t *pbPatchMemPush = pbPatchMem;
468	pbPatchMem += 13;
469
470	pbPatchMem++ = 0xff; / jmp qword [$+8 wrt RIP] */
471	*pbPatchMem++ = 0x25;
472	(uint32_t )pbPatchMem = (uint32_t)(RT_ALIGN_PT(pbPatchMem + 4, 8, uint8_t *) - (pbPatchMem + 4));
473	pbPatchMem = RT_ALIGN_PT(pbPatchMem + 4, 8, uint8_t *);
474	(uint64_t )pbPatchMem = uAddr;
475	pbPatchMem += sizeof(uint64_t);
476
477	/* Push the return address onto stack. Difficult on amd64 without clobbering registers... */
478	uintptr_t uAddrReturn = (uintptr_t)pbPatchMem;
479	pbPatchMemPush++ = 0x68; / push imm32 sign-extended as 64-bit*/
480	(uint32_t )pbPatchMemPush = RT_LO_U32(uAddrReturn);
481	pbPatchMemPush += sizeof(uint32_t);
482	*pbPatchMemPush++ = 0xc7;
483	*pbPatchMemPush++ = 0x44;
484	*pbPatchMemPush++ = 0x24;
485	pbPatchMemPush++ = 0x04; / movl [RSP+4], imm32 */
486	(uint32_t )pbPatchMemPush = RT_HI_U32(uAddrReturn);
487	}
488	else
489	{
490	memcpy(pbPatchMem, pbTarget + offInsn, cbInstr);
491	pbPatchMem += cbInstr;
492	}
493
494	offInsn += cbInstr;
495	}
496
497	pbPatchMem++ = 0xff; / jmp qword [$+8 wrt RIP] */
498	*pbPatchMem++ = 0x25;
499	(uint32_t )pbPatchMem = (uint32_t)(RT_ALIGN_PT(pbPatchMem + 4, 8, uint8_t *) - (pbPatchMem + 4));
500	pbPatchMem = RT_ALIGN_PT(pbPatchMem + 4, 8, uint8_t *);
501	(uint64_t )pbPatchMem = (uintptr_t)&pbTarget[offJmpBack];
502
503	/* Assemble the patch. */
504	Assert(offJmpBack >= 12);
505	pbTarget[0] = 0x48; /* mov rax, qword */
506	pbTarget[1] = 0xb8;
507	(uintptr_t )&pbTarget[2] = (uintptr_t)pfnHook;
508	pbTarget[10] = 0xff; /* jmp rax */
509	pbTarget[11] = 0xe0;
510
511	#else /* !RT_ARCH_AMD64 */
512	/*
513	* Patch 32-bit hosts.
514	*/
515	/* Just use the disassembler to skip 5 bytes or more. */
516	while (offJmpBack < 5)
517	{
518	cbInstr = 1;
519	int rc = DISInstr(pbTarget + offJmpBack, DISCPUMODE_32BIT, &Dis, &cbInstr);
520	if ( RT_FAILURE(rc)
521	\|\| ( (Dis.pCurInstr->fOpType & DISOPTYPE_CONTROLFLOW)
522	&& Dis.pCurInstr->uOpcode != OP_CALL))
523	return VERR_SUPLIB_UNEXPECTED_INSTRUCTION;
524
525	if ( Dis.pCurInstr->uOpcode == OP_CALL
526	&& (Dis.pCurInstr->fOpType & DISOPTYPE_RELATIVE_CONTROLFLOW))
527	cbPatchMem += 10; /* push imm32 + jmp rel32 */
528	else
529	cbPatchMem += cbInstr;
530
531	offJmpBack += cbInstr;
532	}
533
534	/* Allocate suitable exectuable memory available. */
535	uint8_t pbPatchMem = supR3HardenedMainPosixExecMemAlloc(cbPatchMem, pbTarget, false / fRipRelAddr */);
536	if (!pbPatchMem)
537	return VERR_NO_MEMORY;
538
539	/* Assemble the code for resuming the call.*/
540	*ppfnReal = (uintptr_t)pbPatchMem;
541
542	/* Go through the instructions to patch and fixup any relative call instructions. */
543	uint32_t offInsn = 0;
544	while (offInsn < offJmpBack)
545	{
546	cbInstr = 1;
547	int rc = DISInstr(pbTarget + offInsn, DISCPUMODE_32BIT, &Dis, &cbInstr);
548	if ( RT_FAILURE(rc)
549	\|\| ( (Dis.pCurInstr->fOpType & DISOPTYPE_CONTROLFLOW)
550	&& Dis.pCurInstr->uOpcode != OP_CALL))
551	return VERR_SUPLIB_UNEXPECTED_INSTRUCTION;
552
553	if ( Dis.pCurInstr->uOpcode == OP_CALL
554	&& (Dis.pCurInstr->fOpType & DISOPTYPE_RELATIVE_CONTROLFLOW))
555	{
556	/*
557	* Don't use a call instruction directly but push the original return address
558	* onto the stack and use a relative jump to the call target.
559	* The reason here is that on Linux the called method saves the return
560	* address from the stack which will be different from the original because
561	* the code is executed from our patch memory.
562	*
563	* Luckily the call instruction is 5 bytes long which means it is always the
564	* last instruction to patch and we don't need to return from the call
565	* to patch memory anyway but can use this method to resume the original call.
566	*/
567	AssertReturn(offInsn + cbInstr >= offJmpBack, VERR_SUPLIB_UNEXPECTED_INSTRUCTION); /* Must be last instruction! */
568
569	/* push return address */
570	uint32_t const uAddrReturn = (uintptr_t)&pbTarget[offInsn + cbInstr]; /* The return address to push to the stack. */
571
572	pbPatchMem++ = 0x68; / push dword */
573	(uint32_t )pbPatchMem = uAddrReturn;
574	pbPatchMem += sizeof(uint32_t);
575
576	/* jmp rel32 to the call target */
577	uintptr_t const uAddr = uAddrReturn + (int32_t)Dis.Param1.uValue;
578	int32_t const i32DispNew = uAddr - (uintptr_t)&pbPatchMem[5];
579
580	pbPatchMem++ = 0xe9; / jmp rel32 */
581	(int32_t )pbPatchMem = i32DispNew;
582	pbPatchMem += sizeof(int32_t);
583	}
584	else
585	{
586	memcpy(pbPatchMem, pbTarget + offInsn, cbInstr);
587	pbPatchMem += cbInstr;
588	}
589
590	offInsn += cbInstr;
591	}
592
593	pbPatchMem++ = 0xe9; / jmp rel32 */
594	(uint32_t )pbPatchMem = (uintptr_t)&pbTarget[offJmpBack] - ((uintptr_t)pbPatchMem + 4);
595
596	/* Assemble the patch. */
597	Assert(offJmpBack >= 5);
598	pbTarget[0] = 0xe9;
599	(uint32_t )&pbTarget[1] = (uintptr_t)pfnHook - (uintptr_t)&pbTarget[1+4];
600	#endif /* !RT_ARCH_AMD64 */
601
602	/*
603	* Re-seal target (ASSUMING that the shared object either has page aligned
604	* section or that the patch target is far enough from the writable parts).
605	*/
606	rcPsx = mprotect(pvTargetBase, 2 * _4K, PROT_READ \| PROT_EXEC);
607	if (rcPsx == -1)
608	return VERR_SUPLIB_TEXT_NOT_SEALED;
609
610	return VINF_SUCCESS;
611	}
612
613
614	/**
615	* @callback_method_impl{FNSUPHARDENEDSYMRESOLVE, dlopen}
616	*/
617	static DECLCALLBACK(void) supR3HardenedPosixMonitorDlopenResolve(void)
618	{
619	/* Make harmless dlopen call. */
620	void *pv = dlopen(NULL, RTLD_LAZY);
621	if (pv)
622	dlclose(pv);
623	}
624
625
626	#ifdef SUP_HARDENED_WITH_DLMOPEN
627	/**
628	* @callback_method_impl{FNSUPHARDENEDSYMRESOLVE, dlmopen}
629	*/
630	static DECLCALLBACK(void) supR3HardenedPosixMonitorDlmopenResolve(void)
631	{
632	/* Make harmless dlmopen call. */
633	void *pv = dlmopen(LM_ID_BASE, NULL, RTLD_LAZY);
634	if (pv)
635	dlclose(pv);
636	}
637	#endif
638
639	#endif /* SUP_HARDENED_WITHOUT_DLOPEN_PATCHING */
640
641
642	/**
643	* Hardening initialization for POSIX compatible hosts.
644	*
645	* @note Doesn't return on error.
646	*/
647	DECLHIDDEN(void) supR3HardenedPosixInit(void)
648	{
649	#ifndef SUP_HARDENED_WITHOUT_DLOPEN_PATCHING
650	for (unsigned i = 0; i < RT_ELEMENTS(g_aHooks); i++)
651	{
652	PCSUPHARDENEDPOSIXHOOK pHook = &g_aHooks[i];
653	int rc = supR3HardenedMainPosixHookOne(pHook->pszSymbol, pHook->pfnHook, pHook->ppfnRealResume, pHook->pfnResolve);
654	if (RT_FAILURE(rc))
655	supR3HardenedFatalMsg("supR3HardenedPosixInit", kSupInitOp_Integrity, rc,
656	"Failed to hook the %s interface", pHook->pszSymbol);
657	}
658	#endif
659	}
660
661
662
663	/*
664	* assert.cpp
665	*
666	* ASSUMES working DECLHIDDEN or there will be symbol confusion!
667	*/
668
669	RTDATADECL(char) g_szRTAssertMsg1[1024];
670	RTDATADECL(char) g_szRTAssertMsg2[4096];
671	RTDATADECL(const char * volatile) g_pszRTAssertExpr;
672	RTDATADECL(const char * volatile) g_pszRTAssertFile;
673	RTDATADECL(uint32_t volatile) g_u32RTAssertLine;
674	RTDATADECL(const char * volatile) g_pszRTAssertFunction;
675
676	RTDECL(bool) RTAssertMayPanic(void)
677	{
678	return true;
679	}
680
681
682	RTDECL(void) RTAssertMsg1(const char pszExpr, unsigned uLine, const char pszFile, const char *pszFunction)
683	{
684	/*
685	* Fill in the globals.
686	*/
687	g_pszRTAssertExpr = pszExpr;
688	g_pszRTAssertFile = pszFile;
689	g_pszRTAssertFunction = pszFunction;
690	g_u32RTAssertLine = uLine;
691	snprintf(g_szRTAssertMsg1, sizeof(g_szRTAssertMsg1),
692	"\n!!Assertion Failed!!\n"
693	"Expression: %s\n"
694	"Location : %s(%u) %s\n",
695	pszExpr, pszFile, uLine, pszFunction);
696	}
697
698
699	RTDECL(void) RTAssertMsg2V(const char *pszFormat, va_list va)
700	{
701	vsnprintf(g_szRTAssertMsg2, sizeof(g_szRTAssertMsg2), pszFormat, va);
702	if (g_enmSupR3HardenedMainState < SUPR3HARDENEDMAINSTATE_CALLED_TRUSTED_MAIN)
703	supR3HardenedFatalMsg(g_pszRTAssertExpr, kSupInitOp_Misc, VERR_INTERNAL_ERROR,
704	"%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
705	else
706	supR3HardenedError(VERR_INTERNAL_ERROR, false/fFatal/, "%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
707	}
708

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source: vbox/trunk/src/VBox/HostDrivers/Support/posix/SUPR3HardenedMain-posix.cpp@ 100731

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