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| 1 // Copyright (c) 2012 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 <dirent.h> | |
| 6 #include <fcntl.h> | |
| 7 #include <sys/resource.h> | |
| 8 #include <sys/stat.h> | |
| 9 #include <sys/time.h> | |
| 10 #include <sys/types.h> | |
| 11 | |
| 12 #include <limits> | |
| 13 | |
| 14 #include "base/bind.h" | |
| 15 #include "base/callback_helpers.h" | |
| 16 #include "base/command_line.h" | |
| 17 #include "base/logging.h" | |
| 18 #include "base/memory/singleton.h" | |
| 19 #include "base/posix/eintr_wrapper.h" | |
| 20 #include "base/strings/string_number_conversions.h" | |
| 21 #include "base/time/time.h" | |
| 22 #include "content/common/sandbox_linux.h" | |
| 23 #include "content/common/sandbox_seccomp_bpf_linux.h" | |
| 24 #include "content/public/common/content_switches.h" | |
| 25 #include "content/public/common/sandbox_linux.h" | |
| 26 #include "sandbox/linux/services/credentials.h" | |
| 27 #include "sandbox/linux/suid/client/setuid_sandbox_client.h" | |
| 28 | |
| 29 namespace { | |
| 30 | |
| 31 void LogSandboxStarted(const std::string& sandbox_name) { | |
| 32 const CommandLine& command_line = *CommandLine::ForCurrentProcess(); | |
| 33 const std::string process_type = | |
| 34 command_line.GetSwitchValueASCII(switches::kProcessType); | |
| 35 const std::string activated_sandbox = | |
| 36 "Activated " + sandbox_name + " sandbox for process type: " + | |
| 37 process_type + "."; | |
| 38 #if defined(OS_CHROMEOS) | |
| 39 LOG(WARNING) << activated_sandbox; | |
| 40 #else | |
| 41 VLOG(1) << activated_sandbox; | |
| 42 #endif | |
| 43 } | |
| 44 | |
| 45 bool AddResourceLimit(int resource, rlim_t limit) { | |
| 46 struct rlimit old_rlimit; | |
| 47 if (getrlimit(resource, &old_rlimit)) | |
| 48 return false; | |
| 49 // Make sure we don't raise the existing limit. | |
| 50 const struct rlimit new_rlimit = { | |
| 51 std::min(old_rlimit.rlim_cur, limit), | |
| 52 std::min(old_rlimit.rlim_max, limit) | |
| 53 }; | |
| 54 int rc = setrlimit(resource, &new_rlimit); | |
| 55 return rc == 0; | |
| 56 } | |
| 57 | |
| 58 bool IsRunningTSAN() { | |
| 59 #if defined(THREAD_SANITIZER) | |
| 60 return true; | |
| 61 #else | |
| 62 return false; | |
| 63 #endif | |
| 64 } | |
| 65 | |
| 66 } // namespace | |
| 67 | |
| 68 namespace content { | |
| 69 | |
| 70 LinuxSandbox::LinuxSandbox() | |
| 71 : proc_fd_(-1), | |
| 72 seccomp_bpf_started_(false), | |
| 73 pre_initialized_(false), | |
| 74 seccomp_bpf_supported_(false), | |
| 75 setuid_sandbox_client_(sandbox::SetuidSandboxClient::Create()) { | |
| 76 if (setuid_sandbox_client_ == NULL) { | |
| 77 LOG(FATAL) << "Failed to instantiate the setuid sandbox client."; | |
| 78 } | |
| 79 } | |
| 80 | |
| 81 LinuxSandbox::~LinuxSandbox() { | |
| 82 } | |
| 83 | |
| 84 LinuxSandbox* LinuxSandbox::GetInstance() { | |
| 85 LinuxSandbox* instance = Singleton<LinuxSandbox>::get(); | |
| 86 CHECK(instance); | |
| 87 return instance; | |
| 88 } | |
| 89 | |
| 90 #if defined(ADDRESS_SANITIZER) && defined(OS_LINUX) | |
| 91 // ASan API call to notify the tool the sandbox is going to be turned on. | |
| 92 extern "C" void __sanitizer_sandbox_on_notify(void *reserved); | |
| 93 #endif | |
| 94 | |
| 95 void LinuxSandbox::PreinitializeSandbox() { | |
| 96 CHECK(!pre_initialized_); | |
| 97 seccomp_bpf_supported_ = false; | |
| 98 #if defined(ADDRESS_SANITIZER) && defined(OS_LINUX) | |
| 99 // ASan needs to open some resources before the sandbox is enabled. | |
| 100 // This should not fork, not launch threads, not open a directory. | |
| 101 __sanitizer_sandbox_on_notify(/*reserved*/NULL); | |
| 102 #endif | |
| 103 | |
| 104 #if !defined(NDEBUG) | |
| 105 // Open proc_fd_ only in Debug mode so that forgetting to close it doesn't | |
| 106 // produce a sandbox escape in Release mode. | |
| 107 proc_fd_ = open("/proc", O_DIRECTORY | O_RDONLY); | |
| 108 CHECK_GE(proc_fd_, 0); | |
| 109 #endif // !defined(NDEBUG) | |
| 110 // We "pre-warm" the code that detects supports for seccomp BPF. | |
| 111 if (SandboxSeccompBPF::IsSeccompBPFDesired()) { | |
| 112 if (!SandboxSeccompBPF::SupportsSandbox()) { | |
| 113 VLOG(1) << "Lacking support for seccomp-bpf sandbox."; | |
| 114 } else { | |
| 115 seccomp_bpf_supported_ = true; | |
| 116 } | |
| 117 } | |
| 118 pre_initialized_ = true; | |
| 119 } | |
| 120 | |
| 121 bool LinuxSandbox::InitializeSandbox() { | |
| 122 bool seccomp_bpf_started = false; | |
| 123 LinuxSandbox* linux_sandbox = LinuxSandbox::GetInstance(); | |
| 124 // We need to make absolutely sure that our sandbox is "sealed" before | |
| 125 // InitializeSandbox does exit. | |
| 126 base::ScopedClosureRunner sandbox_sealer( | |
| 127 base::Bind(&LinuxSandbox::SealSandbox, base::Unretained(linux_sandbox))); | |
| 128 const std::string process_type = | |
| 129 CommandLine::ForCurrentProcess()->GetSwitchValueASCII( | |
| 130 switches::kProcessType); | |
| 131 | |
| 132 // No matter what, it's always an error to call InitializeSandbox() after | |
| 133 // threads have been created. | |
| 134 if (!linux_sandbox->IsSingleThreaded()) { | |
| 135 std::string error_message = "InitializeSandbox() called with multiple " | |
| 136 "threads in process " + process_type; | |
| 137 // TSAN starts a helper thread. So we don't start the sandbox and don't | |
| 138 // even report an error about it. | |
| 139 if (IsRunningTSAN()) | |
| 140 return false; | |
| 141 // The GPU process is allowed to call InitializeSandbox() with threads for | |
| 142 // now, because it loads third party libraries. | |
| 143 if (process_type != switches::kGpuProcess) | |
| 144 CHECK(false) << error_message; | |
| 145 LOG(ERROR) << error_message; | |
| 146 return false; | |
| 147 } | |
| 148 | |
| 149 DCHECK(!linux_sandbox->HasOpenDirectories()) << | |
| 150 "InitializeSandbox() called after unexpected directories have been " << | |
| 151 "opened. This breaks the security of the setuid sandbox."; | |
| 152 | |
| 153 // Attempt to limit the future size of the address space of the process. | |
| 154 linux_sandbox->LimitAddressSpace(process_type); | |
| 155 | |
| 156 // First, try to enable seccomp-bpf. | |
| 157 seccomp_bpf_started = linux_sandbox->StartSeccompBPF(process_type); | |
| 158 | |
| 159 return seccomp_bpf_started; | |
| 160 } | |
| 161 | |
| 162 int LinuxSandbox::GetStatus() const { | |
| 163 CHECK(pre_initialized_); | |
| 164 int sandbox_flags = 0; | |
| 165 if (setuid_sandbox_client_->IsSandboxed()) { | |
| 166 sandbox_flags |= kSandboxLinuxSUID; | |
| 167 if (setuid_sandbox_client_->IsInNewPIDNamespace()) | |
| 168 sandbox_flags |= kSandboxLinuxPIDNS; | |
| 169 if (setuid_sandbox_client_->IsInNewNETNamespace()) | |
| 170 sandbox_flags |= kSandboxLinuxNetNS; | |
| 171 } | |
| 172 | |
| 173 if (seccomp_bpf_supported() && | |
| 174 SandboxSeccompBPF::ShouldEnableSeccompBPF(switches::kRendererProcess)) { | |
| 175 // We report whether the sandbox will be activated when renderers go | |
| 176 // through sandbox initialization. | |
| 177 sandbox_flags |= kSandboxLinuxSeccompBPF; | |
| 178 } | |
| 179 | |
| 180 return sandbox_flags; | |
| 181 } | |
| 182 | |
| 183 // Threads are counted via /proc/self/task. This is a little hairy because of | |
| 184 // PID namespaces and existing sandboxes, so "self" must really be used instead | |
| 185 // of using the pid. | |
| 186 bool LinuxSandbox::IsSingleThreaded() const { | |
| 187 struct stat task_stat; | |
| 188 int fstat_ret; | |
| 189 if (proc_fd_ >= 0) { | |
| 190 // If a handle to /proc is available, use it. This allows to bypass file | |
| 191 // system restrictions. | |
| 192 fstat_ret = fstatat(proc_fd_, "self/task/", &task_stat, 0); | |
| 193 } else { | |
| 194 // Otherwise, make an attempt to access the file system directly. | |
| 195 fstat_ret = fstatat(AT_FDCWD, "/proc/self/task/", &task_stat, 0); | |
| 196 } | |
| 197 // In Debug mode, it's mandatory to be able to count threads to catch bugs. | |
| 198 #if !defined(NDEBUG) | |
| 199 // Using DCHECK here would be incorrect. DCHECK can be enabled in non | |
| 200 // official release mode. | |
| 201 CHECK_EQ(0, fstat_ret) << "Could not count threads, the sandbox was not " | |
| 202 << "pre-initialized properly."; | |
| 203 #endif // !defined(NDEBUG) | |
| 204 if (fstat_ret) { | |
| 205 // Pretend to be monothreaded if it can't be determined (for instance the | |
| 206 // setuid sandbox is already engaged but no proc_fd_ is available). | |
| 207 return true; | |
| 208 } | |
| 209 | |
| 210 // At least "..", "." and the current thread should be present. | |
| 211 CHECK_LE(3UL, task_stat.st_nlink); | |
| 212 // Counting threads via /proc/self/task could be racy. For the purpose of | |
| 213 // determining if the current proces is monothreaded it works: if at any | |
| 214 // time it becomes monothreaded, it'll stay so. | |
| 215 return task_stat.st_nlink == 3; | |
| 216 } | |
| 217 | |
| 218 bool LinuxSandbox::seccomp_bpf_started() const { | |
| 219 return seccomp_bpf_started_; | |
| 220 } | |
| 221 | |
| 222 sandbox::SetuidSandboxClient* | |
| 223 LinuxSandbox::setuid_sandbox_client() const { | |
| 224 return setuid_sandbox_client_.get(); | |
| 225 } | |
| 226 | |
| 227 // For seccomp-bpf, we use the SandboxSeccompBPF class. | |
| 228 bool LinuxSandbox::StartSeccompBPF(const std::string& process_type) { | |
| 229 CHECK(!seccomp_bpf_started_); | |
| 230 if (!pre_initialized_) | |
| 231 PreinitializeSandbox(); | |
| 232 if (seccomp_bpf_supported()) | |
| 233 seccomp_bpf_started_ = SandboxSeccompBPF::StartSandbox(process_type); | |
| 234 | |
| 235 if (seccomp_bpf_started_) | |
| 236 LogSandboxStarted("seccomp-bpf"); | |
| 237 | |
| 238 return seccomp_bpf_started_; | |
| 239 } | |
| 240 | |
| 241 bool LinuxSandbox::seccomp_bpf_supported() const { | |
| 242 CHECK(pre_initialized_); | |
| 243 return seccomp_bpf_supported_; | |
| 244 } | |
| 245 | |
| 246 bool LinuxSandbox::LimitAddressSpace(const std::string& process_type) { | |
| 247 (void) process_type; | |
| 248 #if !defined(ADDRESS_SANITIZER) | |
| 249 CommandLine* command_line = CommandLine::ForCurrentProcess(); | |
| 250 if (command_line->HasSwitch(switches::kNoSandbox)) { | |
| 251 return false; | |
| 252 } | |
| 253 | |
| 254 // Limit the address space to 4GB. | |
| 255 // This is in the hope of making some kernel exploits more complex and less | |
| 256 // reliable. It also limits sprays a little on 64-bit. | |
| 257 rlim_t address_space_limit = std::numeric_limits<uint32_t>::max(); | |
| 258 #if defined(__LP64__) | |
| 259 // On 64 bits, V8 and possibly others will reserve massive memory ranges and | |
| 260 // rely on on-demand paging for allocation. Unfortunately, even | |
| 261 // MADV_DONTNEED ranges count towards RLIMIT_AS so this is not an option. | |
| 262 // See crbug.com/169327 for a discussion. | |
| 263 // On the GPU process, irrespective of V8, we can exhaust a 4GB address space | |
| 264 // under normal usage, see crbug.com/271119 | |
| 265 // For now, increase limit to 16GB for renderer and worker and gpu processes | |
| 266 // to accomodate. | |
| 267 if (process_type == switches::kRendererProcess || | |
| 268 process_type == switches::kWorkerProcess || | |
| 269 process_type == switches::kGpuProcess) { | |
| 270 address_space_limit = 1L << 34; | |
| 271 } | |
| 272 #endif // defined(__LP64__) | |
| 273 | |
| 274 // On all platforms, add a limit to the brk() heap that would prevent | |
| 275 // allocations that can't be index by an int. | |
| 276 const rlim_t kNewDataSegmentMaxSize = std::numeric_limits<int>::max(); | |
| 277 | |
| 278 bool limited_as = AddResourceLimit(RLIMIT_AS, address_space_limit); | |
| 279 bool limited_data = AddResourceLimit(RLIMIT_DATA, kNewDataSegmentMaxSize); | |
| 280 return limited_as && limited_data; | |
| 281 #else | |
| 282 return false; | |
| 283 #endif // !defined(ADDRESS_SANITIZER) | |
| 284 } | |
| 285 | |
| 286 bool LinuxSandbox::HasOpenDirectories() { | |
| 287 return sandbox::Credentials().HasOpenDirectory(proc_fd_); | |
| 288 } | |
| 289 | |
| 290 void LinuxSandbox::SealSandbox() { | |
| 291 if (proc_fd_ >= 0) { | |
| 292 int ret = IGNORE_EINTR(close(proc_fd_)); | |
| 293 CHECK_EQ(0, ret); | |
| 294 proc_fd_ = -1; | |
| 295 } | |
| 296 } | |
| 297 | |
| 298 } // namespace content | |
| 299 | |
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Chromium Code Reviews
Issue 99133015:
Linux Sandbox: split the GPU policies to their own file. (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src