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1 /* | |
2 * Copyright (c) 2012 The Native Client Authors. All rights reserved. | |
3 * Use of this source code is governed by a BSD-style license that can be | |
4 * found in the LICENSE file. | |
5 */ | |
6 | |
7 /* | |
8 * ncvalidate_details.c | |
9 * Attach detailed error reporter to the NaCl validator. Does a second | |
10 * walk of the instructions to find instructions that explicitly branch | |
11 * to illegal addresses. | |
12 * | |
13 * See function NCJumpSummarize in ncvalidate.c for a the terse version | |
14 * which doesn't require a second pass. | |
15 */ | |
16 | |
17 #include "native_client/src/trusted/validator/x86/ncval_seg_sfi/ncvalidate_detai
led.h" | |
18 | |
19 #include "native_client/src/trusted/validator/x86/ncval_seg_sfi/ncdecode.h" | |
20 #include "native_client/src/trusted/validator/x86/ncval_seg_sfi/ncvalidate_inter
naltypes.h" | |
21 | |
22 static void NCJumpSummarizeDetailed(struct NCValidatorState* vstate); | |
23 | |
24 | |
25 /* Null method for decoder state. */ | |
26 static void NCNullDecoderStateMethod(struct NCValidatorState* vstate) { | |
27 } | |
28 | |
29 /* Detailed (summary) error check on target value, defined in the given decoder | |
30 * instruction. | |
31 */ | |
32 static void NCJumpCheck(struct NCValidatorState* vstate, | |
33 const NCDecoderInst* dinst, | |
34 int32_t jump_offset) { | |
35 NaClPcAddress target = (dinst->inst_addr + dinst->inst.bytes.length | |
36 + jump_offset); | |
37 | |
38 if (target < vstate->codesize && !NCGetAdrTable(target, vstate->vttable)) { | |
39 if (NCGetAdrTable(target, vstate->pattern_nonfirst_insts_table)) { | |
40 NCBadInstructionError(dinst, "Jumps into middle of nacl pattern"); | |
41 } else { | |
42 NCBadInstructionError(dinst, "Doesn't jump to instruction address"); | |
43 } | |
44 NCStatsBadTarget(vstate); | |
45 } | |
46 } | |
47 | |
48 /* Detailed (summary) error check for a byte jump instruction. | |
49 * Note: This code should match the corresponding validator check | |
50 * function ValidateJmp8 in ncvalidate.c. | |
51 */ | |
52 static void NCInstCheckJmp8(const NCDecoderInst* dinst) { | |
53 int8_t offset = NCInstBytesByte(&dinst->inst_bytes, | |
54 dinst->inst.prefixbytes+1); | |
55 struct NCValidatorState* vstate = NCVALIDATOR_STATE_DOWNCAST(dinst->dstate); | |
56 NCJumpCheck(vstate, dinst, offset); | |
57 } | |
58 | |
59 /* Detailed (summary) error check for a jump condition instruction. | |
60 * Note: This code should match the corresponding validator check | |
61 * function ValidateJmpz in ncvalidate.c. | |
62 */ | |
63 static void NCInstCheckJmpz(const NCDecoderInst* dinst) { | |
64 NCInstBytesPtr opcode; | |
65 uint8_t opcode0; | |
66 int32_t offset; | |
67 NCValidatorState* vstate = NCVALIDATOR_STATE_DOWNCAST(dinst->dstate); | |
68 NCInstBytesPtrInitInc(&opcode, &dinst->inst_bytes, | |
69 dinst->inst.prefixbytes); | |
70 opcode0 = NCInstBytesByte(&opcode, 0); | |
71 if (opcode0 == 0x0f) { | |
72 /* Multbyte opcode. Intruction is of form: | |
73 * 0F80 .. 0F8F: jCC $Jz | |
74 */ | |
75 NCInstBytesPtr opcode_2; | |
76 NCInstBytesPtrInitInc(&opcode_2, &opcode, 2); | |
77 offset = NCInstBytesInt32(&opcode_2, dinst->inst.immbytes); | |
78 } else { | |
79 /* Single byte opcode. Must be one of: | |
80 * E8: call $Jz | |
81 * E9: jmp $Jx | |
82 */ | |
83 NCInstBytesPtr opcode_1; | |
84 NCInstBytesPtrInitInc(&opcode_1, &opcode, 1); | |
85 offset = NCInstBytesInt32(&opcode_1, dinst->inst.immbytes); | |
86 } | |
87 NCJumpCheck(vstate, dinst, offset); | |
88 } | |
89 | |
90 /* Decoder action to perform to detect bad jumps during detailed | |
91 * (summarization) error checking. | |
92 */ | |
93 static Bool NCInstLayoutCheck(const NCDecoderInst* dinst) { | |
94 NCValidatorState* vstate; | |
95 NaClPcAddress start; | |
96 NaClPcAddress end; | |
97 NaClPcAddress i; | |
98 if (dinst == NULL) return TRUE; | |
99 vstate = NCVALIDATOR_STATE_DOWNCAST(dinst->dstate); | |
100 | |
101 /* Check that if first instruction is a basic block, it isn't in the middle | |
102 * of a pattern. | |
103 */ | |
104 start = dinst->inst_addr; | |
105 if ((0 == (start % vstate->bundle_size)) && | |
106 NCGetAdrTable(start, vstate->pattern_nonfirst_insts_table)) { | |
107 NCBadInstructionError( | |
108 dinst, | |
109 "Instruction begins basic block, but in middle of nacl pattern\n"); | |
110 NCStatsBadAlignment(vstate); | |
111 } | |
112 | |
113 /* Check that instruction doesn't cross block boundaries. */ | |
114 end = start + NCInstBytesLength(&dinst->inst_bytes); | |
115 for (i = start + 1; i < end; ++i) { | |
116 if (0 == (i % vstate->bundle_size)) { | |
117 NCBadInstructionError(dinst, "Instruction crosses basic block alignment"); | |
118 NCStatsBadAlignment(vstate); | |
119 } | |
120 } | |
121 | |
122 /* Check jump targets. */ | |
123 switch (dinst->opinfo->insttype) { | |
124 case NACLi_JMP8: | |
125 NCInstCheckJmp8(dinst); | |
126 break; | |
127 case NACLi_JMPZ: | |
128 NCInstCheckJmpz(dinst); | |
129 break; | |
130 default: | |
131 break; | |
132 } | |
133 return TRUE; | |
134 } | |
135 | |
136 /* Detailed (summary) error reporting. Rather than looking at summary | |
137 * information collected during the first pass, this code rewalks the | |
138 * instructions are reports each instruction that causes a problem. | |
139 */ | |
140 static void NCJumpSummarizeDetailed(struct NCValidatorState* vstate) { | |
141 /* Rewalk the code to find instructions that break rules. */ | |
142 NCDecoderState* dstate = &vstate->dstate; | |
143 NaClErrorReporter* reporter = dstate->error_reporter; | |
144 NCDecoderStateConstruct(dstate, dstate->mbase, dstate->vbase, dstate->size, | |
145 vstate->inst_buffer, kNCValidatorInstBufferSize); | |
146 dstate->action_fn = NCInstLayoutCheck; | |
147 dstate->new_segment_fn = (NCDecoderStateMethod) NCNullDecoderStateMethod; | |
148 dstate->internal_error_fn = (NCDecoderStateMethod) NCNullDecoderStateMethod; | |
149 dstate->internal_error_fn = (NCDecoderStateMethod) NCStatsInternalError; | |
150 NCDecoderStateSetErrorReporter(dstate, reporter); | |
151 NCDecoderStateDecode(dstate); | |
152 } | |
153 | |
154 struct NCValidatorState *NCValidateInitDetailed( | |
155 const NaClPcAddress vbase, | |
156 const NaClMemorySize codesize, | |
157 const NaClCPUFeaturesX86 *features) { | |
158 struct NCValidatorState *vstate = NCValidateInit(vbase, codesize, | |
159 FALSE, features); | |
160 if (NULL != vstate) { | |
161 vstate->summarize_fn = NCJumpSummarizeDetailed; | |
162 vstate->pattern_nonfirst_insts_table = | |
163 (uint8_t *)calloc(NCIATOffset(codesize) + 1, 1); | |
164 if (NULL == vstate->pattern_nonfirst_insts_table) { | |
165 if (NULL != vstate->kttable) free(vstate->kttable); | |
166 if (NULL != vstate->vttable) free(vstate->vttable); | |
167 free(vstate); | |
168 return NULL; | |
169 } | |
170 } | |
171 return vstate; | |
172 } | |
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