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1 // Copyright 2014 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 "components/nacl/loader/nonsfi/nonsfi_sandbox.h" | |
6 | |
7 #include <errno.h> | |
8 #include <fcntl.h> | |
9 #include <linux/net.h> | |
10 #include <sys/prctl.h> | |
11 #include <sys/ptrace.h> | |
12 #include <sys/mman.h> | |
13 #include <sys/socket.h> | |
14 #include <sys/syscall.h> | |
15 | |
16 #include "base/basictypes.h" | |
17 #include "base/logging.h" | |
18 #include "build/build_config.h" | |
19 #include "content/public/common/sandbox_init.h" | |
20 #include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h" | |
21 #include "sandbox/linux/seccomp-bpf/sandbox_bpf.h" | |
22 #include "sandbox/linux/seccomp-bpf/sandbox_bpf_policy.h" | |
23 #include "sandbox/linux/seccomp-bpf/trap.h" | |
24 #include "sandbox/linux/services/linux_syscalls.h" | |
25 | |
26 #if defined(__arm__) && !defined(MAP_STACK) | |
27 #define MAP_STACK 0x20000 // Daisy build environment has old headers. | |
28 #endif | |
29 | |
30 using sandbox::ErrorCode; | |
31 using sandbox::SandboxBPF; | |
32 using sandbox::SandboxBPFPolicy; | |
33 | |
34 namespace nacl { | |
35 namespace nonsfi { | |
36 namespace { | |
37 | |
38 ErrorCode RestrictFcntlCommandsForNaClNonSfi(SandboxBPF* sb) { | |
39 ErrorCode::ArgType mask_long_type; | |
40 if (sizeof(long) == 8) | |
41 mask_long_type = ErrorCode::TP_64BIT; | |
42 else if (sizeof(long) == 4) | |
43 mask_long_type = ErrorCode::TP_32BIT; | |
44 else | |
45 NOTREACHED(); | |
46 // We allow following cases: | |
47 // 1. F_SETFD + FD_CLOEXEC: libevent's epoll_init uses this. | |
48 // 2. F_GETFL: Used by SetNonBlocking in | |
49 // message_pump_libevent.cc and Channel::ChannelImpl::CreatePipe | |
50 // in ipc_channel_posix.cc. Note that the latter does not work | |
51 // with EPERM. | |
52 // 3. F_SETFL: Used by evutil_make_socket_nonblocking in | |
53 // libevent and SetNonBlocking. As the latter mix O_NONBLOCK to | |
54 // the return value of F_GETFL, so we need to allow O_ACCMODE in | |
55 // addition to O_NONBLOCK. | |
56 unsigned long denied_mask = ~(O_ACCMODE | O_NONBLOCK); | |
57 return sb->Cond(1, ErrorCode::TP_32BIT, | |
58 ErrorCode::OP_EQUAL, F_SETFD, | |
59 sb->Cond(2, mask_long_type, | |
60 ErrorCode::OP_EQUAL, FD_CLOEXEC, | |
61 ErrorCode(ErrorCode::ERR_ALLOWED), | |
62 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)), | |
63 sb->Cond(1, ErrorCode::TP_32BIT, | |
64 ErrorCode::OP_EQUAL, F_GETFL, | |
65 ErrorCode(ErrorCode::ERR_ALLOWED), | |
66 sb->Cond(1, ErrorCode::TP_32BIT, | |
67 ErrorCode::OP_EQUAL, F_SETFL, | |
68 sb->Cond(2, mask_long_type, | |
69 ErrorCode::OP_HAS_ANY_BITS, denied_mask, | |
70 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL), | |
71 ErrorCode(ErrorCode::ERR_ALLOWED)), | |
72 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)))); | |
73 } | |
74 | |
75 ErrorCode RestrictCloneForNaClNonSfi(SandboxBPF* sb) { | |
76 // We allow clone only for new thread creation. | |
77 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
78 CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | | |
79 CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS | | |
80 CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID, | |
81 ErrorCode(ErrorCode::ERR_ALLOWED), | |
82 sb->Trap(sandbox::SIGSYSCloneFailure, NULL)); | |
83 } | |
84 | |
85 ErrorCode RestrictPrctlForNaClNonSfi(SandboxBPF* sb) { | |
86 // base::PlatformThread::SetName() uses PR_SET_NAME so we return | |
87 // EPERM for it. Otherwise, we will raise SIGSYS. | |
88 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
89 PR_SET_NAME, ErrorCode(EPERM), | |
90 sb->Trap(sandbox::SIGSYSPrctlFailure, NULL)); | |
91 } | |
92 | |
93 #if defined(__i386__) | |
94 ErrorCode RestrictSocketcallForNaClNonSfi(SandboxBPF* sb) { | |
95 // We only allow socketpair, sendmsg, and recvmsg. | |
96 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
97 SYS_SOCKETPAIR, | |
98 ErrorCode(ErrorCode::ERR_ALLOWED), | |
99 sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
100 SYS_SENDMSG, | |
101 ErrorCode(ErrorCode::ERR_ALLOWED), | |
102 sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
103 SYS_RECVMSG, | |
104 ErrorCode(ErrorCode::ERR_ALLOWED), | |
105 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)))); | |
106 } | |
107 #endif | |
108 | |
109 ErrorCode RestrictMemoryProtectionForNaClNonSfi(SandboxBPF* sb, int argno) { | |
110 // TODO(jln, keescook, drewry): Limit the use of mmap/mprotect by | |
111 // adding some features to linux kernel. | |
112 uint32_t denied_mask = ~(PROT_READ | PROT_WRITE | PROT_EXEC); | |
113 return sb->Cond(argno, ErrorCode::TP_32BIT, | |
114 ErrorCode::OP_HAS_ANY_BITS, | |
115 denied_mask, | |
116 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL), | |
117 ErrorCode(ErrorCode::ERR_ALLOWED)); | |
118 } | |
119 | |
120 ErrorCode RestrictMmapForNaClNonSfi(SandboxBPF* sb) { | |
121 uint32_t denied_flag_mask = ~(MAP_SHARED | MAP_PRIVATE | MAP_ANONYMOUS | | |
122 MAP_STACK | MAP_FIXED); | |
123 return sb->Cond(3, ErrorCode::TP_32BIT, | |
124 ErrorCode::OP_HAS_ANY_BITS, | |
125 denied_flag_mask, | |
126 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL), | |
127 RestrictMemoryProtectionForNaClNonSfi(sb, 2)); | |
128 } | |
129 | |
130 ErrorCode RestrictSocketpairForNaClNonSfi(SandboxBPF* sb) { | |
131 // Only allow AF_UNIX, PF_UNIX. Crash if anything else is seen. | |
132 COMPILE_ASSERT(AF_UNIX == PF_UNIX, af_unix_pf_unix_different); | |
133 return sb->Cond(0, ErrorCode::TP_32BIT, | |
134 ErrorCode::OP_EQUAL, AF_UNIX, | |
135 ErrorCode(ErrorCode::ERR_ALLOWED), | |
136 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)); | |
137 } | |
138 | |
139 // The seccomp sandbox policy for NaCl non-SFI mode. Note that this | |
140 // policy must be as strong as possible, as non-SFI mode heavily | |
141 // depends on seccomp sandbox. | |
142 class NaClNonSfiBPFSandboxPolicy : public SandboxBPFPolicy { | |
143 public: | |
144 explicit NaClNonSfiBPFSandboxPolicy() { | |
145 } | |
146 virtual ~NaClNonSfiBPFSandboxPolicy() {} | |
147 | |
148 virtual ErrorCode EvaluateSyscall(SandboxBPF* sandbox_compiler, | |
149 int system_call_number) const OVERRIDE; | |
150 | |
151 private: | |
152 DISALLOW_COPY_AND_ASSIGN(NaClNonSfiBPFSandboxPolicy); | |
153 }; | |
154 | |
155 ErrorCode NaClNonSfiBPFSandboxPolicy::EvaluateSyscall( | |
156 SandboxBPF* sb, int sysno) const { | |
157 switch (sysno) { | |
158 // Allowed syscalls. | |
159 #if defined(__i386__) || defined(__arm__) | |
160 case __NR__llseek: | |
161 #endif | |
162 #if defined(__x86_64__) | |
163 case __NR_lseek: | |
164 #endif | |
165 case __NR_clock_gettime: | |
166 case __NR_close: | |
167 case __NR_dup: | |
168 case __NR_dup2: | |
169 case __NR_epoll_create: | |
170 case __NR_epoll_ctl: | |
171 case __NR_epoll_wait: | |
172 case __NR_exit: | |
173 case __NR_exit_group: | |
174 #if defined(__i386__) || defined(__arm__) | |
175 case __NR_fstat64: | |
176 #endif | |
177 #if defined(__x86_64__) | |
178 case __NR_fstat: | |
179 #endif | |
180 case __NR_futex: | |
181 case __NR_gettid: | |
182 case __NR_gettimeofday: | |
183 case __NR_munmap: | |
184 case __NR_nanosleep: | |
185 case __NR_pipe: | |
186 case __NR_pread64: | |
187 case __NR_read: | |
188 case __NR_restart_syscall: | |
189 case __NR_sched_yield: | |
190 case __NR_sigaltstack: | |
191 case __NR_write: | |
192 #if defined(__arm__) | |
193 case __ARM_NR_cacheflush: | |
194 #endif | |
195 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
196 // __NR_times needed as clock() is called by CommandBufferHelper, which is | |
197 // used by NaCl applications that use Pepper's 3D interfaces. | |
198 // See crbug.com/264856 for details. | |
199 case __NR_times: | |
200 // NaCl runtime exposes clock_getres to untrusted code. | |
201 case __NR_clock_getres: | |
202 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
203 | |
204 // It is allowed to call the following syscalls, but they just | |
205 // return EPERM. | |
206 case __NR_ptrace: | |
207 // For RunSandboxSanityChecks(). | |
208 return ErrorCode(EPERM); | |
209 case __NR_set_robust_list: | |
210 // glibc uses this for its pthread implementation. If we return | |
211 // EPERM for this, glibc will stop using this. | |
212 // TODO(hamaji): newlib does not use this. Make this SIGTRAP once | |
213 // we have switched to newlib. | |
214 return ErrorCode(EPERM); | |
jln (very slow on Chromium)
2014/04/08 00:51:10
Do you want to group all the EPERM into a separate
hamaji
2014/04/09 21:09:09
Done.
| |
215 #if defined(__i386__) || defined(__arm__) | |
216 case __NR_getegid32: | |
217 case __NR_geteuid32: | |
218 case __NR_getgid32: | |
219 case __NR_getuid32: | |
220 #endif | |
221 #if defined(__x86_64__) | |
222 case __NR_getegid: | |
223 case __NR_geteuid: | |
224 case __NR_getgid: | |
225 case __NR_getuid: | |
226 #endif | |
227 // third_party/libevent uses them, but we can just return -1 from | |
228 // them as it is just checking getuid() != geteuid() and | |
229 // getgid() != getegid() | |
230 return ErrorCode(EPERM); | |
231 #if defined(__i386__) || defined(__x86_64__) | |
232 case __NR_time: | |
233 // This is obsolete in ARM EABI, but x86 glibc indirectly calls | |
234 // this in sysconf. | |
235 return ErrorCode(EPERM); | |
236 #endif | |
237 case __NR_open: | |
238 // EPERM instead of SIGSYS as glibc tries to open files in /proc. | |
239 // TODO(hamaji): Remove this when we switch to newlib. | |
240 return ErrorCode(EPERM); | |
241 | |
242 case __NR_brk: | |
243 // The behavior of brk on Linux is different from other system | |
244 // calls. It does not return errno but the current break on | |
245 // failure. glibc thinks brk failed the return value of brk | |
246 // is lesser than the requested address (i.e., brk(addr) < addr) | |
247 // So, glibc thinks brk succeeded if we return -EPERM and we | |
248 // need to return zero instead. | |
249 return ErrorCode(0); | |
250 | |
251 case __NR_madvise: | |
252 // tcmalloc calls madvise in TCMalloc_SystemRelease. | |
253 return ErrorCode(EPERM); | |
254 | |
255 case __NR_clone: | |
256 return RestrictCloneForNaClNonSfi(sb); | |
257 case __NR_prctl: | |
258 return RestrictPrctlForNaClNonSfi(sb); | |
259 | |
260 #if defined(__i386__) | |
261 case __NR_socketcall: | |
262 return RestrictSocketcallForNaClNonSfi(sb); | |
263 #endif | |
264 #if defined(__x86_64__) || defined(__arm__) | |
265 case __NR_recvmsg: | |
jln (very slow on Chromium)
2014/04/08 00:51:10
These guys are pretty problematic :(
hamaji
2014/04/09 21:09:09
One of my naive question: isn't it possible to add
| |
266 case __NR_sendmsg: | |
267 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
268 | |
269 case __NR_socketpair: | |
270 return RestrictSocketpairForNaClNonSfi(sb); | |
271 #endif | |
272 | |
273 #if defined(__x86_64__) | |
274 case __NR_fcntl: | |
275 #endif | |
276 #if defined(__i386__) || defined(__arm__) | |
277 case __NR_fcntl64: | |
278 #endif | |
279 return RestrictFcntlCommandsForNaClNonSfi(sb); | |
280 | |
281 #if defined(__x86_64__) | |
282 case __NR_mmap: | |
283 #endif | |
284 #if defined(__i386__) || defined(__arm__) | |
285 case __NR_mmap2: | |
286 #endif | |
287 return RestrictMmapForNaClNonSfi(sb); | |
288 | |
289 case __NR_mprotect: | |
290 return RestrictMemoryProtectionForNaClNonSfi(sb, 2); | |
291 | |
292 default: | |
293 return sb->Trap(sandbox::CrashSIGSYS_Handler, NULL); | |
294 } | |
295 } | |
296 | |
297 void RunSandboxSanityChecks() { | |
298 errno = 0; | |
299 // Make a ptrace request with an invalid PID. | |
300 long ptrace_ret = ptrace(PTRACE_PEEKUSER, -1 /* pid */, NULL, NULL); | |
301 CHECK_EQ(-1, ptrace_ret); | |
302 // Without the sandbox on, this ptrace call would ESRCH instead. | |
303 CHECK_EQ(EPERM, errno); | |
304 } | |
305 | |
306 } // namespace | |
307 | |
308 void InitializeBPFSandbox() { | |
309 bool sandbox_is_initialized = content::InitializeSandbox( | |
310 scoped_ptr<SandboxBPFPolicy>(new NaClNonSfiBPFSandboxPolicy())); | |
311 CHECK(sandbox_is_initialized) | |
312 << "InitializeBPFSandbox for non-SFI NaCl failed"; | |
313 RunSandboxSanityChecks(); | |
314 } | |
315 | |
316 } // namespace nonsfi | |
317 } // namespace nacl | |
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