nealsid | b0baafc | 2009-08-17 23:12:53 +0000 | [diff] [blame] | 1 | // Copyright (c) 2009, Google Inc. |
| 2 | // All rights reserved. |
| 3 | // |
| 4 | // Redistribution and use in source and binary forms, with or without |
| 5 | // modification, are permitted provided that the following conditions are |
| 6 | // met: |
| 7 | // |
| 8 | // * Redistributions of source code must retain the above copyright |
| 9 | // notice, this list of conditions and the following disclaimer. |
| 10 | // * Redistributions in binary form must reproduce the above |
| 11 | // copyright notice, this list of conditions and the following disclaimer |
| 12 | // in the documentation and/or other materials provided with the |
| 13 | // distribution. |
| 14 | // * Neither the name of Google Inc. nor the names of its |
| 15 | // contributors may be used to endorse or promote products derived from |
| 16 | // this software without specific prior written permission. |
| 17 | // |
| 18 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 19 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 20 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 21 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 22 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 23 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 24 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 25 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 26 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 27 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 28 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 29 | |
| 30 | // This code deals with the mechanics of getting information about a crashed |
| 31 | // process. Since this code may run in a compromised address space, the same |
| 32 | // rules apply as detailed at the top of minidump_writer.h: no libc calls and |
| 33 | // use the alternative allocator. |
| 34 | |
| 35 | #include "client/linux/minidump_writer/linux_dumper.h" |
| 36 | |
| 37 | #include <assert.h> |
| 38 | #include <limits.h> |
| 39 | #include <stddef.h> |
| 40 | #include <stdlib.h> |
| 41 | #include <stdio.h> |
| 42 | #include <string.h> |
| 43 | |
| 44 | #include <unistd.h> |
| 45 | #include <errno.h> |
| 46 | #include <fcntl.h> |
| 47 | |
| 48 | #include <sys/types.h> |
| 49 | #include <sys/ptrace.h> |
| 50 | #include <sys/wait.h> |
| 51 | |
| 52 | #include "client/linux/minidump_writer/directory_reader.h" |
| 53 | #include "client/linux/minidump_writer/line_reader.h" |
| 54 | #include "common/linux/linux_libc_support.h" |
| 55 | #include "common/linux/linux_syscall_support.h" |
| 56 | |
| 57 | // Suspend a thread by attaching to it. |
| 58 | static bool SuspendThread(pid_t pid) { |
| 59 | // This may fail if the thread has just died or debugged. |
| 60 | errno = 0; |
| 61 | if (sys_ptrace(PTRACE_ATTACH, pid, NULL, NULL) != 0 && |
| 62 | errno != 0) { |
| 63 | return false; |
| 64 | } |
| 65 | while (sys_waitpid(pid, NULL, __WALL) < 0) { |
| 66 | if (errno != EINTR) { |
| 67 | sys_ptrace(PTRACE_DETACH, pid, NULL, NULL); |
| 68 | return false; |
| 69 | } |
| 70 | } |
| 71 | return true; |
| 72 | } |
| 73 | |
| 74 | // Resume a thread by detaching from it. |
| 75 | static bool ResumeThread(pid_t pid) { |
| 76 | return sys_ptrace(PTRACE_DETACH, pid, NULL, NULL) >= 0; |
| 77 | } |
| 78 | |
| 79 | namespace google_breakpad { |
| 80 | |
| 81 | LinuxDumper::LinuxDumper(int pid) |
| 82 | : pid_(pid), |
| 83 | threads_suspened_(false), |
| 84 | threads_(&allocator_, 8), |
| 85 | mappings_(&allocator_) { |
| 86 | } |
| 87 | |
| 88 | bool LinuxDumper::Init() { |
| 89 | return EnumerateThreads(&threads_) && |
| 90 | EnumerateMappings(&mappings_); |
| 91 | } |
| 92 | |
| 93 | bool LinuxDumper::ThreadsSuspend() { |
| 94 | if (threads_suspened_) |
| 95 | return true; |
| 96 | bool good = true; |
| 97 | for (size_t i = 0; i < threads_.size(); ++i) |
| 98 | good &= SuspendThread(threads_[i]); |
| 99 | threads_suspened_ = true; |
| 100 | return good; |
| 101 | } |
| 102 | |
| 103 | bool LinuxDumper::ThreadsResume() { |
| 104 | if (!threads_suspened_) |
| 105 | return false; |
| 106 | bool good = true; |
| 107 | for (size_t i = 0; i < threads_.size(); ++i) |
| 108 | good &= ResumeThread(threads_[i]); |
| 109 | threads_suspened_ = false; |
| 110 | return good; |
| 111 | } |
| 112 | |
| 113 | void |
| 114 | LinuxDumper::BuildProcPath(char* path, pid_t pid, const char* node) const { |
| 115 | assert(path); |
| 116 | if (!path) { |
| 117 | return; |
| 118 | } |
| 119 | |
| 120 | path[0] = '\0'; |
| 121 | |
| 122 | const unsigned pid_len = my_int_len(pid); |
| 123 | |
| 124 | assert(node); |
| 125 | if (!node) { |
| 126 | return; |
| 127 | } |
| 128 | |
| 129 | size_t node_len = my_strlen(node); |
| 130 | assert(node_len < NAME_MAX); |
| 131 | if (node_len >= NAME_MAX) { |
| 132 | return; |
| 133 | } |
| 134 | |
| 135 | assert(node_len > 0); |
| 136 | if (node_len == 0) { |
| 137 | return; |
| 138 | } |
| 139 | |
| 140 | assert(pid > 0); |
| 141 | if (pid <= 0) { |
| 142 | return; |
| 143 | } |
| 144 | |
| 145 | const size_t total_length = 6 + pid_len + 1 + node_len; |
| 146 | |
| 147 | assert(total_length < NAME_MAX); |
| 148 | if (total_length >= NAME_MAX) { |
| 149 | return; |
| 150 | } |
| 151 | |
| 152 | memcpy(path, "/proc/", 6); |
| 153 | my_itos(path + 6, pid, pid_len); |
| 154 | memcpy(path + 6 + pid_len, "/", 1); |
| 155 | memcpy(path + 6 + pid_len + 1, node, node_len); |
| 156 | memcpy(path + total_length, "\0", 1); |
| 157 | } |
| 158 | |
| 159 | void* |
| 160 | LinuxDumper::FindBeginningOfLinuxGateSharedLibrary(const pid_t pid) const { |
| 161 | char auxv_path[80]; |
| 162 | BuildProcPath(auxv_path, pid, "auxv"); |
| 163 | |
| 164 | // If BuildProcPath errors out due to invalid input, we'll handle it when |
| 165 | // we try to sys_open the file. |
| 166 | |
| 167 | // Find the AT_SYSINFO_EHDR entry for linux-gate.so |
| 168 | // See http://www.trilithium.com/johan/2005/08/linux-gate/ for more |
| 169 | // information. |
| 170 | int fd = sys_open(auxv_path, O_RDONLY, 0); |
| 171 | if (fd < 0) { |
| 172 | return NULL; |
| 173 | } |
| 174 | |
| 175 | elf_aux_entry one_aux_entry; |
| 176 | while (sys_read(fd, |
| 177 | &one_aux_entry, |
| 178 | sizeof(elf_aux_entry)) == sizeof(elf_aux_entry) && |
| 179 | one_aux_entry.a_type != AT_NULL) { |
| 180 | if (one_aux_entry.a_type == AT_SYSINFO_EHDR) { |
| 181 | close(fd); |
| 182 | return reinterpret_cast<void*>(one_aux_entry.a_un.a_val); |
| 183 | } |
| 184 | } |
| 185 | close(fd); |
| 186 | return NULL; |
| 187 | } |
| 188 | |
| 189 | bool |
| 190 | LinuxDumper::EnumerateMappings(wasteful_vector<MappingInfo*>* result) const { |
| 191 | char maps_path[80]; |
| 192 | BuildProcPath(maps_path, pid_, "maps"); |
| 193 | |
| 194 | // linux_gate_loc is the beginning of the kernel's mapping of |
| 195 | // linux-gate.so in the process. It doesn't actually show up in the |
| 196 | // maps list as a filename, so we use the aux vector to find it's |
| 197 | // load location and special case it's entry when creating the list |
| 198 | // of mappings. |
| 199 | const void* linux_gate_loc; |
| 200 | linux_gate_loc = FindBeginningOfLinuxGateSharedLibrary(pid_); |
| 201 | |
| 202 | const int fd = sys_open(maps_path, O_RDONLY, 0); |
| 203 | if (fd < 0) |
| 204 | return false; |
| 205 | LineReader* const line_reader = new(allocator_) LineReader(fd); |
| 206 | |
| 207 | const char* line; |
| 208 | unsigned line_len; |
| 209 | while (line_reader->GetNextLine(&line, &line_len)) { |
| 210 | uintptr_t start_addr, end_addr, offset; |
| 211 | |
| 212 | const char* i1 = my_read_hex_ptr(&start_addr, line); |
| 213 | if (*i1 == '-') { |
| 214 | const char* i2 = my_read_hex_ptr(&end_addr, i1 + 1); |
| 215 | if (*i2 == ' ') { |
| 216 | const char* i3 = my_read_hex_ptr(&offset, i2 + 6 /* skip ' rwxp ' */); |
| 217 | if (*i3 == ' ') { |
| 218 | MappingInfo* const module = new(allocator_) MappingInfo; |
| 219 | memset(module, 0, sizeof(MappingInfo)); |
| 220 | module->start_addr = start_addr; |
| 221 | module->size = end_addr - start_addr; |
| 222 | module->offset = offset; |
| 223 | const char* name = NULL; |
| 224 | // Only copy name if the name is a valid path name, or if |
| 225 | // we've found the VDSO image |
| 226 | if ((name = my_strchr(line, '/')) != NULL) { |
| 227 | const unsigned l = my_strlen(name); |
| 228 | if (l < sizeof(module->name)) |
| 229 | memcpy(module->name, name, l); |
| 230 | } else if (linux_gate_loc && |
| 231 | reinterpret_cast<void*>(module->start_addr) == |
| 232 | linux_gate_loc) { |
| 233 | memcpy(module->name, |
| 234 | kLinuxGateLibraryName, |
| 235 | my_strlen(kLinuxGateLibraryName)); |
| 236 | module->offset = 0; |
| 237 | } |
| 238 | result->push_back(module); |
| 239 | } |
| 240 | } |
| 241 | } |
| 242 | line_reader->PopLine(line_len); |
| 243 | } |
| 244 | |
| 245 | sys_close(fd); |
| 246 | |
| 247 | return result->size() > 0; |
| 248 | } |
| 249 | |
| 250 | // Parse /proc/$pid/task to list all the threads of the process identified by |
| 251 | // pid. |
| 252 | bool LinuxDumper::EnumerateThreads(wasteful_vector<pid_t>* result) const { |
| 253 | char task_path[80]; |
| 254 | BuildProcPath(task_path, pid_, "task"); |
| 255 | |
| 256 | const int fd = sys_open(task_path, O_RDONLY | O_DIRECTORY, 0); |
| 257 | if (fd < 0) |
| 258 | return false; |
| 259 | DirectoryReader* dir_reader = new(allocator_) DirectoryReader(fd); |
| 260 | |
| 261 | // The directory may contain duplicate entries which we filter by assuming |
| 262 | // that they are consecutive. |
| 263 | int last_tid = -1; |
| 264 | const char* dent_name; |
| 265 | while (dir_reader->GetNextEntry(&dent_name)) { |
| 266 | if (my_strcmp(dent_name, ".") && |
| 267 | my_strcmp(dent_name, "..")) { |
| 268 | int tid = 0; |
| 269 | if (my_strtoui(&tid, dent_name) && |
| 270 | last_tid != tid) { |
| 271 | last_tid = tid; |
| 272 | result->push_back(tid); |
| 273 | } |
| 274 | } |
| 275 | dir_reader->PopEntry(); |
| 276 | } |
| 277 | |
| 278 | sys_close(fd); |
| 279 | return true; |
| 280 | } |
| 281 | |
| 282 | // Read thread info from /proc/$pid/status. |
| 283 | // Fill out the |tgid|, |ppid| and |pid| members of |info|. If unavailible, |
| 284 | // these members are set to -1. Returns true iff all three members are |
| 285 | // availible. |
| 286 | bool LinuxDumper::ThreadInfoGet(pid_t tid, ThreadInfo* info) { |
| 287 | assert(info != NULL); |
| 288 | char status_path[80]; |
| 289 | BuildProcPath(status_path, tid, "status"); |
| 290 | |
| 291 | const int fd = open(status_path, O_RDONLY); |
| 292 | if (fd < 0) |
| 293 | return false; |
| 294 | |
| 295 | LineReader* const line_reader = new(allocator_) LineReader(fd); |
| 296 | const char* line; |
| 297 | unsigned line_len; |
| 298 | |
| 299 | info->ppid = info->tgid = -1; |
| 300 | |
| 301 | while (line_reader->GetNextLine(&line, &line_len)) { |
| 302 | if (my_strncmp("Tgid:\t", line, 6) == 0) { |
| 303 | my_strtoui(&info->tgid, line + 6); |
| 304 | } else if (my_strncmp("PPid:\t", line, 6) == 0) { |
| 305 | my_strtoui(&info->ppid, line + 6); |
| 306 | } |
| 307 | |
| 308 | line_reader->PopLine(line_len); |
| 309 | } |
| 310 | |
| 311 | if (info->ppid == -1 || info->tgid == -1) |
| 312 | return false; |
| 313 | |
| 314 | if (sys_ptrace(PTRACE_GETREGS, tid, NULL, &info->regs) == -1 || |
| 315 | sys_ptrace(PTRACE_GETFPREGS, tid, NULL, &info->fpregs) == -1) { |
| 316 | return false; |
| 317 | } |
| 318 | |
nealsid | 096992f | 2009-12-01 21:35:52 +0000 | [diff] [blame^] | 319 | #if defined(__i386) |
nealsid | b0baafc | 2009-08-17 23:12:53 +0000 | [diff] [blame] | 320 | if (sys_ptrace(PTRACE_GETFPXREGS, tid, NULL, &info->fpxregs) == -1) |
| 321 | return false; |
nealsid | 096992f | 2009-12-01 21:35:52 +0000 | [diff] [blame^] | 322 | #endif |
nealsid | b0baafc | 2009-08-17 23:12:53 +0000 | [diff] [blame] | 323 | |
nealsid | 096992f | 2009-12-01 21:35:52 +0000 | [diff] [blame^] | 324 | #if defined(__i386) || defined(__x86_64) |
nealsid | b0baafc | 2009-08-17 23:12:53 +0000 | [diff] [blame] | 325 | for (unsigned i = 0; i < ThreadInfo::kNumDebugRegisters; ++i) { |
| 326 | if (sys_ptrace( |
| 327 | PTRACE_PEEKUSER, tid, |
| 328 | reinterpret_cast<void*> (offsetof(struct user, |
| 329 | u_debugreg[0]) + i * |
| 330 | sizeof(debugreg_t)), |
| 331 | &info->dregs[i]) == -1) { |
| 332 | return false; |
| 333 | } |
| 334 | } |
| 335 | #endif |
| 336 | |
| 337 | const uint8_t* stack_pointer; |
| 338 | #if defined(__i386) |
| 339 | memcpy(&stack_pointer, &info->regs.esp, sizeof(info->regs.esp)); |
| 340 | #elif defined(__x86_64) |
| 341 | memcpy(&stack_pointer, &info->regs.rsp, sizeof(info->regs.rsp)); |
| 342 | #else |
| 343 | #error "This code hasn't been ported to your platform yet." |
| 344 | #endif |
| 345 | |
| 346 | if (!GetStackInfo(&info->stack, &info->stack_len, |
| 347 | (uintptr_t) stack_pointer)) |
| 348 | return false; |
| 349 | |
| 350 | return true; |
| 351 | } |
| 352 | |
| 353 | // Get information about the stack, given the stack pointer. We don't try to |
| 354 | // walk the stack since we might not have all the information needed to do |
| 355 | // unwind. So we just grab, up to, 32k of stack. |
| 356 | bool LinuxDumper::GetStackInfo(const void** stack, size_t* stack_len, |
| 357 | uintptr_t int_stack_pointer) { |
| 358 | #if defined(__i386) || defined(__x86_64) |
| 359 | static const bool stack_grows_down = true; |
| 360 | static const uintptr_t page_size = 4096; |
| 361 | #else |
| 362 | #error "This code has not been ported to your platform yet." |
| 363 | #endif |
| 364 | // Move the stack pointer to the bottom of the page that it's in. |
| 365 | uint8_t* const stack_pointer = |
| 366 | reinterpret_cast<uint8_t*>(int_stack_pointer & ~(page_size - 1)); |
| 367 | |
| 368 | // The number of bytes of stack which we try to capture. |
| 369 | static unsigned kStackToCapture = 32 * 1024; |
| 370 | |
| 371 | const MappingInfo* mapping = FindMapping(stack_pointer); |
| 372 | if (!mapping) |
| 373 | return false; |
| 374 | if (stack_grows_down) { |
| 375 | const ptrdiff_t offset = stack_pointer - (uint8_t*) mapping->start_addr; |
| 376 | const ptrdiff_t distance_to_end = |
| 377 | static_cast<ptrdiff_t>(mapping->size) - offset; |
| 378 | *stack_len = distance_to_end > kStackToCapture ? |
| 379 | kStackToCapture : distance_to_end; |
| 380 | *stack = stack_pointer; |
| 381 | } else { |
| 382 | const ptrdiff_t offset = stack_pointer - (uint8_t*) mapping->start_addr; |
| 383 | *stack_len = offset > kStackToCapture ? kStackToCapture : offset; |
| 384 | *stack = stack_pointer - *stack_len; |
| 385 | } |
| 386 | |
| 387 | return true; |
| 388 | } |
| 389 | |
| 390 | // static |
| 391 | void LinuxDumper::CopyFromProcess(void* dest, pid_t child, const void* src, |
| 392 | size_t length) { |
| 393 | unsigned long tmp; |
| 394 | size_t done = 0; |
| 395 | static const size_t word_size = sizeof(tmp); |
| 396 | uint8_t* const local = (uint8_t*) dest; |
| 397 | uint8_t* const remote = (uint8_t*) src; |
| 398 | |
| 399 | while (done < length) { |
| 400 | const size_t l = length - done > word_size ? word_size : length - done; |
| 401 | if (sys_ptrace(PTRACE_PEEKDATA, child, remote + done, &tmp) == -1) |
| 402 | tmp = 0; |
| 403 | memcpy(local + done, &tmp, l); |
| 404 | done += l; |
| 405 | } |
| 406 | } |
| 407 | |
| 408 | // Find the mapping which the given memory address falls in. |
| 409 | const MappingInfo* LinuxDumper::FindMapping(const void* address) const { |
| 410 | const uintptr_t addr = (uintptr_t) address; |
| 411 | |
| 412 | for (size_t i = 0; i < mappings_.size(); ++i) { |
| 413 | const uintptr_t start = static_cast<uintptr_t>(mappings_[i]->start_addr); |
| 414 | if (addr >= start && addr - start < mappings_[i]->size) |
| 415 | return mappings_[i]; |
| 416 | } |
| 417 | |
| 418 | return NULL; |
| 419 | } |
| 420 | |
| 421 | } // namespace google_breakpad |