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| 1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include <string> | |
| 6 #include <map> | |
| 7 | |
| 8 #include "sandbox/src/policy_low_level.h" | |
| 9 #include "base/basictypes.h" | |
| 10 | |
| 11 namespace { | |
| 12 | |
| 13 // A single rule can use at most this amount of memory. | |
| 14 const size_t kRuleBufferSize = 1024*4; | |
| 15 | |
| 16 // The possible states of the string matching opcode generator. | |
| 17 enum { | |
| 18 PENDING_NONE, | |
| 19 PENDING_ASTERISK, // Have seen an '*' but have not generated an opcode. | |
| 20 PENDING_QMARK, // Have seen an '?' but have not generated an opcode. | |
| 21 }; | |
| 22 | |
| 23 // The category of the last character seen by the string matching opcode | |
| 24 // generator. | |
| 25 const uint32 kLastCharIsNone = 0; | |
| 26 const uint32 kLastCharIsAlpha = 1; | |
| 27 const uint32 kLastCharIsWild = 2; | |
| 28 const uint32 kLastCharIsAsterisk = kLastCharIsWild + 4; | |
| 29 const uint32 kLastCharIsQuestionM = kLastCharIsWild + 8; | |
| 30 } | |
| 31 | |
| 32 namespace sandbox { | |
| 33 | |
| 34 // Adding a rule is nothing more than pushing it into an stl container. Done() | |
| 35 // is called for the rule in case the code that made the rule in the first | |
| 36 // place has not done it. | |
| 37 bool LowLevelPolicy::AddRule(int service, PolicyRule* rule) { | |
| 38 if (!rule->Done()) { | |
| 39 return false; | |
| 40 } | |
| 41 | |
| 42 PolicyRule* local_rule = new PolicyRule(*rule); | |
| 43 RuleNode node = {local_rule, service}; | |
| 44 rules_.push_back(node); | |
| 45 return true; | |
| 46 } | |
| 47 | |
| 48 LowLevelPolicy::~LowLevelPolicy() { | |
| 49 // Delete all the rules. | |
| 50 typedef std::list<RuleNode> RuleNodes; | |
| 51 for (RuleNodes::iterator it = rules_.begin(); it != rules_.end(); ++it) { | |
| 52 delete it->rule; | |
| 53 } | |
| 54 } | |
| 55 | |
| 56 // Here is where the heavy byte shuffling is done. We take all the rules and | |
| 57 // 'compile' them into a single memory region. Now, the rules are in random | |
| 58 // order so the first step is to reorganize them into a stl map that is keyed | |
| 59 // by the service id and as a value contains a list with all the rules that | |
| 60 // belong to that service. Then we enter the big for-loop where we carve a | |
| 61 // memory zone for the opcodes and the data and call RebindCopy on each rule | |
| 62 // so they all end up nicely packed in the policy_store_. | |
| 63 bool LowLevelPolicy::Done() { | |
| 64 typedef std::list<RuleNode> RuleNodes; | |
| 65 typedef std::list<const PolicyRule*> RuleList; | |
| 66 typedef std::map<uint32, RuleList> Mmap; | |
| 67 Mmap mmap; | |
| 68 | |
| 69 for (RuleNodes::iterator it = rules_.begin(); it != rules_.end(); ++it) { | |
| 70 mmap[it->service].push_back(it->rule); | |
| 71 } | |
| 72 | |
| 73 PolicyBuffer* current_buffer = &policy_store_->data[0]; | |
| 74 char* buffer_end = reinterpret_cast<char*>(current_buffer) + | |
| 75 policy_store_->data_size; | |
| 76 size_t avail_size = policy_store_->data_size; | |
| 77 | |
| 78 for (Mmap::iterator it = mmap.begin(); it != mmap.end(); ++it) { | |
| 79 uint32 service = (*it).first; | |
| 80 if (service >= kMaxServiceCount) { | |
| 81 return false; | |
| 82 } | |
| 83 policy_store_->entry[service] = current_buffer; | |
| 84 | |
| 85 RuleList::iterator rules_it = (*it).second.begin(); | |
| 86 RuleList::iterator rules_it_end = (*it).second.end(); | |
| 87 | |
| 88 size_t svc_opcode_count = 0; | |
| 89 | |
| 90 for (; rules_it != rules_it_end; ++rules_it) { | |
| 91 const PolicyRule* rule = (*rules_it); | |
| 92 size_t op_count = rule->GetOpcodeCount(); | |
| 93 | |
| 94 size_t opcodes_size = op_count * sizeof(PolicyOpcode); | |
| 95 if (avail_size < opcodes_size) { | |
| 96 return false; | |
| 97 } | |
| 98 size_t data_size = avail_size - opcodes_size; | |
| 99 PolicyOpcode* opcodes_start = ¤t_buffer->opcodes[svc_opcode_count]; | |
| 100 if (!rule->RebindCopy(opcodes_start, opcodes_size, | |
| 101 buffer_end, &data_size)) { | |
| 102 return false; | |
| 103 } | |
| 104 size_t used = avail_size - data_size; | |
| 105 buffer_end -= used; | |
| 106 avail_size -= used; | |
| 107 svc_opcode_count += op_count; | |
| 108 } | |
| 109 | |
| 110 current_buffer->opcode_count += svc_opcode_count; | |
| 111 size_t policy_byte_count = (svc_opcode_count * sizeof(PolicyOpcode)) | |
| 112 / sizeof(current_buffer[0]); | |
| 113 current_buffer = ¤t_buffer[policy_byte_count + 1]; | |
| 114 } | |
| 115 | |
| 116 return true; | |
| 117 } | |
| 118 | |
| 119 PolicyRule::PolicyRule(EvalResult action) | |
| 120 : action_(action), done_(false) { | |
| 121 char* memory = new char[sizeof(PolicyBuffer) + kRuleBufferSize]; | |
| 122 buffer_ = reinterpret_cast<PolicyBuffer*>(memory); | |
| 123 buffer_->opcode_count = 0; | |
| 124 opcode_factory_ = new OpcodeFactory(buffer_, | |
| 125 kRuleBufferSize + sizeof(PolicyOpcode)); | |
| 126 } | |
| 127 | |
| 128 PolicyRule::PolicyRule(const PolicyRule& other) { | |
| 129 if (this == &other) | |
| 130 return; | |
| 131 action_ = other.action_; | |
| 132 done_ = other.done_; | |
| 133 size_t buffer_size = sizeof(PolicyBuffer) + kRuleBufferSize; | |
| 134 char* memory = new char[buffer_size]; | |
| 135 buffer_ = reinterpret_cast<PolicyBuffer*>(memory); | |
| 136 memcpy(buffer_, other.buffer_, buffer_size); | |
| 137 | |
| 138 char* opcode_buffer = reinterpret_cast<char*>(&buffer_->opcodes[0]); | |
| 139 char* buffer_end = &opcode_buffer[kRuleBufferSize + sizeof(PolicyOpcode)]; | |
| 140 char* next_opcode = &opcode_buffer[GetOpcodeCount() * sizeof(PolicyOpcode)]; | |
| 141 opcode_factory_ = new OpcodeFactory(next_opcode, buffer_end - next_opcode); | |
| 142 } | |
| 143 | |
| 144 // This function get called from a simple state machine implemented in | |
| 145 // AddStringMatch() which passes the current state (in state) and it passes | |
| 146 // true in last_call if AddStringMatch() has finished processing the input | |
| 147 // pattern string and this would be the last call to generate any pending | |
| 148 // opcode. The skip_count is the currently accumulated number of '?' seen so | |
| 149 // far and once the associated opcode is generated this function sets it back | |
| 150 // to zero. | |
| 151 bool PolicyRule::GenStringOpcode(RuleType rule_type, | |
| 152 StringMatchOptions match_opts, | |
| 153 uint16 parameter, int state, bool last_call, | |
| 154 int* skip_count, std::wstring* fragment) { | |
| 155 | |
| 156 // The last opcode must: | |
| 157 // 1) Always clear the context. | |
| 158 // 2) Preserve the negation. | |
| 159 // 3) Remove the 'OR' mode flag. | |
| 160 uint32 options = kPolNone; | |
| 161 if (last_call) { | |
| 162 if (IF_NOT == rule_type) { | |
| 163 options = kPolClearContext | kPolNegateEval; | |
| 164 } else { | |
| 165 options = kPolClearContext; | |
| 166 } | |
| 167 } else if (IF_NOT == rule_type) { | |
| 168 options = kPolUseOREval | kPolNegateEval; | |
| 169 } | |
| 170 | |
| 171 PolicyOpcode* op = NULL; | |
| 172 | |
| 173 // The fragment string contains the accumulated characters to match with, it | |
| 174 // never contains wildcards (unless they have been escaped) and while there | |
| 175 // is no fragment there is no new string match opcode to generate. | |
| 176 if (fragment->empty()) { | |
| 177 // There is no new opcode to generate but in the last call we have to fix | |
| 178 // the previous opcode because it was really the last but we did not know | |
| 179 // it at that time. | |
| 180 if (last_call && (buffer_->opcode_count > 0)) { | |
| 181 op = &buffer_->opcodes[buffer_->opcode_count - 1]; | |
| 182 op->SetOptions(options); | |
| 183 } | |
| 184 return true; | |
| 185 } | |
| 186 | |
| 187 if (PENDING_ASTERISK == state) { | |
| 188 if (last_call) { | |
| 189 op = opcode_factory_->MakeOpWStringMatch(parameter, fragment->c_str(), | |
| 190 kSeekToEnd, match_opts, | |
| 191 options); | |
| 192 } else { | |
| 193 op = opcode_factory_->MakeOpWStringMatch(parameter, fragment->c_str(), | |
| 194 kSeekForward, match_opts, | |
| 195 options); | |
| 196 } | |
| 197 | |
| 198 } else if (PENDING_QMARK == state) { | |
| 199 op = opcode_factory_->MakeOpWStringMatch(parameter, fragment->c_str(), | |
| 200 *skip_count, match_opts, options); | |
| 201 *skip_count = 0; | |
| 202 } else { | |
| 203 if (last_call) { | |
| 204 match_opts = static_cast<StringMatchOptions>(EXACT_LENGHT | match_opts); | |
| 205 } | |
| 206 op = opcode_factory_->MakeOpWStringMatch(parameter, fragment->c_str(), 0, | |
| 207 match_opts, options); | |
| 208 } | |
| 209 if (NULL == op) { | |
| 210 return false; | |
| 211 } | |
| 212 ++buffer_->opcode_count; | |
| 213 fragment->clear(); | |
| 214 return true; | |
| 215 } | |
| 216 | |
| 217 bool PolicyRule::AddStringMatch(RuleType rule_type, int16 parameter, | |
| 218 const wchar_t* string, | |
| 219 StringMatchOptions match_opts) { | |
| 220 if (done_) { | |
| 221 // Do not allow to add more rules after generating the action opcode. | |
| 222 return false; | |
| 223 } | |
| 224 | |
| 225 const wchar_t* current_char = string; | |
| 226 uint32 last_char = kLastCharIsNone; | |
| 227 int state = PENDING_NONE; | |
| 228 int skip_count = 0; // counts how many '?' we have seen in a row. | |
| 229 std::wstring fragment; // accumulates the non-wildcard part of the string. | |
| 230 | |
| 231 while (L'\0' != *current_char) { | |
| 232 switch (*current_char) { | |
| 233 case L'*': | |
| 234 if (kLastCharIsWild & last_char) { | |
| 235 // '**' and '&*' is an error. | |
| 236 return false; | |
| 237 } | |
| 238 if (!GenStringOpcode(rule_type, match_opts, parameter, | |
| 239 state, false, &skip_count, &fragment)) { | |
| 240 return false; | |
| 241 } | |
| 242 last_char = kLastCharIsAsterisk; | |
| 243 state = PENDING_ASTERISK; | |
| 244 break; | |
| 245 case L'?': | |
| 246 if (kLastCharIsAsterisk == last_char) { | |
| 247 // '*?' is an error. | |
| 248 return false; | |
| 249 } | |
| 250 if (!GenStringOpcode(rule_type, match_opts, parameter, | |
| 251 state, false, &skip_count, &fragment)) { | |
| 252 return false; | |
| 253 } | |
| 254 ++skip_count; | |
| 255 last_char = kLastCharIsQuestionM; | |
| 256 state = PENDING_QMARK; | |
| 257 break; | |
| 258 case L'/': | |
| 259 // Note: "/?" is an escaped '?'. Eat the slash and fall through. | |
| 260 if (L'?' == current_char[1]) { | |
| 261 ++current_char; | |
| 262 } | |
| 263 default: | |
| 264 fragment += *current_char; | |
| 265 last_char = kLastCharIsAlpha; | |
| 266 } | |
| 267 ++current_char; | |
| 268 } | |
| 269 | |
| 270 if (!GenStringOpcode(rule_type, match_opts, parameter, | |
| 271 state, true, &skip_count, &fragment)) { | |
| 272 return false; | |
| 273 } | |
| 274 return true; | |
| 275 } | |
| 276 | |
| 277 bool PolicyRule::AddNumberMatch(RuleType rule_type, int16 parameter, | |
| 278 unsigned long number, RuleOp comparison_op) { | |
| 279 if (done_) { | |
| 280 // Do not allow to add more rules after generating the action opcode. | |
| 281 return false; | |
| 282 } | |
| 283 uint32 opts = (rule_type == IF_NOT)? kPolNegateEval : kPolNone; | |
| 284 | |
| 285 if (EQUAL == comparison_op) { | |
| 286 if (NULL == opcode_factory_->MakeOpNumberMatch(parameter, number, opts)) { | |
| 287 return false; | |
| 288 } | |
| 289 } else if (AND == comparison_op) { | |
| 290 if (NULL == opcode_factory_->MakeOpUlongAndMatch(parameter, number, opts)) { | |
| 291 return false; | |
| 292 } | |
| 293 } | |
| 294 ++buffer_->opcode_count; | |
| 295 return true; | |
| 296 } | |
| 297 | |
| 298 bool PolicyRule::Done() { | |
| 299 if (done_) { | |
| 300 return true; | |
| 301 } | |
| 302 if (NULL == opcode_factory_->MakeOpAction(action_, kPolNone)) { | |
| 303 return false; | |
| 304 } | |
| 305 ++buffer_->opcode_count; | |
| 306 done_ = true; | |
| 307 return true; | |
| 308 } | |
| 309 | |
| 310 bool PolicyRule::RebindCopy(PolicyOpcode* opcode_start, size_t opcode_size, | |
| 311 char* data_start, size_t* data_size) const { | |
| 312 size_t count = buffer_->opcode_count; | |
| 313 for (size_t ix = 0; ix != count; ++ix) { | |
| 314 if (opcode_size < sizeof(PolicyOpcode)) { | |
| 315 return false; | |
| 316 } | |
| 317 PolicyOpcode& opcode = buffer_->opcodes[ix]; | |
| 318 *opcode_start = opcode; | |
| 319 if (OP_WSTRING_MATCH == opcode.GetID()) { | |
| 320 // For this opcode argument 0 is a delta to the string and argument 1 | |
| 321 // is the length (in chars) of the string. | |
| 322 const wchar_t* str = opcode.GetRelativeString(0); | |
| 323 size_t str_len; | |
| 324 opcode.GetArgument(1, &str_len); | |
| 325 str_len = str_len * sizeof(wchar_t); | |
| 326 if ((*data_size) < str_len) { | |
| 327 return false; | |
| 328 } | |
| 329 *data_size -= str_len; | |
| 330 data_start -= str_len; | |
| 331 memcpy(data_start, str, str_len); | |
| 332 // Recompute the string displacement | |
| 333 ptrdiff_t delta = data_start - reinterpret_cast<char*>(opcode_start); | |
| 334 opcode_start->SetArgument(0, delta); | |
| 335 } | |
| 336 ++opcode_start; | |
| 337 opcode_size -= sizeof(PolicyOpcode); | |
| 338 } | |
| 339 | |
| 340 return true; | |
| 341 } | |
| 342 | |
| 343 PolicyRule::~PolicyRule() { | |
| 344 delete [] reinterpret_cast<char*>(buffer_); | |
| 345 delete opcode_factory_; | |
| 346 } | |
| 347 | |
| 348 } // namespace sandbox | |
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