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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 | |
33 namespace nacl { | |
34 namespace nonsfi { | |
35 namespace { | |
36 | |
37 ErrorCode RestrictFcntlCommandsForNaClNonSfi(SandboxBPF* sb) { | |
38 ErrorCode::ArgType mask_long_type; | |
39 if (sizeof(long) == 8) | |
40 mask_long_type = ErrorCode::TP_64BIT; | |
41 else if (sizeof(long) == 4) | |
42 mask_long_type = ErrorCode::TP_32BIT; | |
43 else | |
44 NOTREACHED(); | |
45 // We allow following cases: | |
46 // 1. F_SETFD + FD_CLOEXEC: libevent's epoll_init uses this. | |
47 // 2. F_GETFL: Used by SetNonBlocking in | |
48 // message_pump_libevent.cc and Channel::ChannelImpl::CreatePipe | |
49 // in ipc_channel_posix.cc. Note that the latter does not work | |
50 // with EPERM. | |
51 // 3. F_SETFL: Used by evutil_make_socket_nonblocking in | |
52 // libevent and SetNonBlocking. As the latter mix O_NONBLOCK to | |
53 // the return value of F_GETFL, so we need to allow O_ACCMODE in | |
54 // addition to O_NONBLOCK. | |
55 unsigned long denied_mask = ~(O_ACCMODE | O_NONBLOCK); | |
jln (very slow on Chromium)
2014/04/10 21:00:03
Nit: const
hamaji
2014/04/11 01:25:58
Done.
| |
56 return sb->Cond(1, ErrorCode::TP_32BIT, | |
57 ErrorCode::OP_EQUAL, F_SETFD, | |
58 sb->Cond(2, mask_long_type, | |
59 ErrorCode::OP_EQUAL, FD_CLOEXEC, | |
60 ErrorCode(ErrorCode::ERR_ALLOWED), | |
61 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)), | |
62 sb->Cond(1, ErrorCode::TP_32BIT, | |
63 ErrorCode::OP_EQUAL, F_GETFL, | |
64 ErrorCode(ErrorCode::ERR_ALLOWED), | |
65 sb->Cond(1, ErrorCode::TP_32BIT, | |
66 ErrorCode::OP_EQUAL, F_SETFL, | |
67 sb->Cond(2, mask_long_type, | |
68 ErrorCode::OP_HAS_ANY_BITS, denied_mask, | |
69 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL), | |
70 ErrorCode(ErrorCode::ERR_ALLOWED)), | |
71 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)))); | |
jln (very slow on Chromium)
2014/04/10 21:00:03
Nit: shouldn't this be aligned with sb->Cond()?
hamaji
2014/04/11 01:25:58
Done. I'm not sure if I understand the preferred s
| |
72 } | |
73 | |
74 ErrorCode RestrictCloneForNaClNonSfi(SandboxBPF* sb) { | |
75 // We allow clone only for new thread creation. | |
76 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
77 CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | | |
78 CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS | | |
79 CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID, | |
80 ErrorCode(ErrorCode::ERR_ALLOWED), | |
81 sb->Trap(sandbox::SIGSYSCloneFailure, NULL)); | |
82 } | |
83 | |
84 ErrorCode RestrictPrctlForNaClNonSfi(SandboxBPF* sb) { | |
85 // base::PlatformThread::SetName() uses PR_SET_NAME so we return | |
86 // EPERM for it. Otherwise, we will raise SIGSYS. | |
87 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
88 PR_SET_NAME, ErrorCode(EPERM), | |
89 sb->Trap(sandbox::SIGSYSPrctlFailure, NULL)); | |
90 } | |
91 | |
92 #if defined(__i386__) | |
93 ErrorCode RestrictSocketcallForNaClNonSfi(SandboxBPF* sb) { | |
94 // We only allow socketpair, sendmsg, and recvmsg. | |
95 return sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
96 SYS_SOCKETPAIR, | |
97 ErrorCode(ErrorCode::ERR_ALLOWED), | |
98 sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
99 SYS_SENDMSG, | |
100 ErrorCode(ErrorCode::ERR_ALLOWED), | |
101 sb->Cond(0, ErrorCode::TP_32BIT, ErrorCode::OP_EQUAL, | |
102 SYS_RECVMSG, | |
103 ErrorCode(ErrorCode::ERR_ALLOWED), | |
104 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL)))); | |
105 } | |
106 #endif | |
107 | |
108 ErrorCode RestrictMemoryProtectionForNaClNonSfi(SandboxBPF* sb, int argno) { | |
109 // TODO(jln, keescook, drewry): Limit the use of mmap/mprotect by | |
110 // adding some features to linux kernel. | |
111 uint32_t denied_mask = ~(PROT_READ | PROT_WRITE | PROT_EXEC); | |
jln (very slow on Chromium)
2014/04/10 21:00:03
nit const:
hamaji
2014/04/11 01:25:58
Done.
| |
112 return sb->Cond(argno, ErrorCode::TP_32BIT, | |
113 ErrorCode::OP_HAS_ANY_BITS, | |
114 denied_mask, | |
115 sb->Trap(sandbox::CrashSIGSYS_Handler, NULL), | |
116 ErrorCode(ErrorCode::ERR_ALLOWED)); | |
117 } | |
118 | |
119 ErrorCode RestrictMmapForNaClNonSfi(SandboxBPF* sb) { | |
120 uint32_t denied_flag_mask = ~(MAP_SHARED | MAP_PRIVATE | MAP_ANONYMOUS | | |
hamaji
2014/04/11 01:25:58
I also added const here.
| |
121 MAP_STACK | MAP_FIXED); | |
122 // TODO(hamaji): Disallow RWX mmap. | |
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 bool IsGracefullyDenied(int sysno) { | |
140 switch (sysno) { | |
141 // third_party/libevent uses them, but we can just return -1 from | |
142 // them as it is just checking getuid() != geteuid() and | |
143 // getgid() != getegid() | |
144 #if defined(__i386__) || defined(__arm__) | |
145 case __NR_getegid32: | |
146 case __NR_geteuid32: | |
147 case __NR_getgid32: | |
148 case __NR_getuid32: | |
149 #endif | |
150 #if defined(__x86_64__) | |
151 case __NR_getegid: | |
152 case __NR_geteuid: | |
153 case __NR_getgid: | |
154 case __NR_getuid: | |
155 #endif | |
156 // tcmalloc calls madvise in TCMalloc_SystemRelease. | |
157 case __NR_madvise: | |
158 // EPERM instead of SIGSYS as glibc tries to open files in /proc. | |
159 // TODO(hamaji): Remove this when we switch to newlib. | |
160 case __NR_open: | |
161 // For RunSandboxSanityChecks(). | |
162 case __NR_ptrace: | |
163 // glibc uses this for its pthread implementation. If we return | |
164 // EPERM for this, glibc will stop using this. | |
165 // TODO(hamaji): newlib does not use this. Make this SIGTRAP once | |
166 // we have switched to newlib. | |
167 case __NR_set_robust_list: | |
168 // This is obsolete in ARM EABI, but x86 glibc indirectly calls | |
169 // this in sysconf. | |
170 #if defined(__i386__) || defined(__x86_64__) | |
171 case __NR_time: | |
172 #endif | |
173 return true; | |
174 | |
175 default: | |
176 return false; | |
177 } | |
178 } | |
179 | |
180 void RunSandboxSanityChecks() { | |
181 errno = 0; | |
182 // Make a ptrace request with an invalid PID. | |
183 long ptrace_ret = ptrace(PTRACE_PEEKUSER, -1 /* pid */, NULL, NULL); | |
184 CHECK_EQ(-1, ptrace_ret); | |
185 // Without the sandbox on, this ptrace call would ESRCH instead. | |
186 CHECK_EQ(EPERM, errno); | |
187 } | |
188 | |
189 } // namespace | |
190 | |
191 ErrorCode NaClNonSfiBPFSandboxPolicy::EvaluateSyscall( | |
192 SandboxBPF* sb, int sysno) const { | |
193 return EvaluateSyscallImpl(sb, sysno, NULL); | |
194 } | |
195 | |
196 ErrorCode NaClNonSfiBPFSandboxPolicy::EvaluateSyscallImpl( | |
197 SandboxBPF* sb, int sysno, void*) { | |
198 switch (sysno) { | |
199 // Allowed syscalls. | |
200 #if defined(__i386__) || defined(__arm__) | |
201 case __NR__llseek: | |
202 #endif | |
203 #if defined(__x86_64__) | |
204 case __NR_lseek: | |
205 #endif | |
206 case __NR_clock_gettime: | |
207 case __NR_close: | |
208 case __NR_dup: | |
209 case __NR_dup2: | |
210 case __NR_epoll_create: | |
211 case __NR_epoll_ctl: | |
212 case __NR_epoll_wait: | |
213 case __NR_exit: | |
214 case __NR_exit_group: | |
215 #if defined(__i386__) || defined(__arm__) | |
216 case __NR_fstat64: | |
217 #endif | |
218 #if defined(__x86_64__) | |
219 case __NR_fstat: | |
220 #endif | |
221 case __NR_futex: | |
222 case __NR_gettid: | |
223 case __NR_gettimeofday: | |
224 case __NR_munmap: | |
225 case __NR_nanosleep: | |
226 case __NR_pipe: | |
227 case __NR_pread64: | |
228 case __NR_read: | |
229 case __NR_restart_syscall: | |
230 case __NR_sched_yield: | |
231 case __NR_sigaltstack: | |
232 case __NR_write: | |
233 #if defined(__arm__) | |
234 case __ARM_NR_cacheflush: | |
235 #endif | |
236 // NaCl runtime exposes clock_getres to untrusted code. | |
237 case __NR_clock_getres: | |
238 // __NR_times needed as clock() is called by CommandBufferHelper, which is | |
239 // used by NaCl applications that use Pepper's 3D interfaces. | |
240 // See crbug.com/264856 for details. | |
241 case __NR_times: | |
242 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
243 | |
244 case __NR_clone: | |
245 return RestrictCloneForNaClNonSfi(sb); | |
246 | |
247 #if defined(__x86_64__) | |
248 case __NR_fcntl: | |
249 #endif | |
250 #if defined(__i386__) || defined(__arm__) | |
251 case __NR_fcntl64: | |
252 #endif | |
253 return RestrictFcntlCommandsForNaClNonSfi(sb); | |
254 | |
255 #if defined(__x86_64__) | |
256 case __NR_mmap: | |
257 #endif | |
258 #if defined(__i386__) || defined(__arm__) | |
259 case __NR_mmap2: | |
260 #endif | |
261 return RestrictMmapForNaClNonSfi(sb); | |
262 case __NR_mprotect: | |
263 return RestrictMemoryProtectionForNaClNonSfi(sb, 2); | |
264 | |
265 case __NR_prctl: | |
266 return RestrictPrctlForNaClNonSfi(sb); | |
267 | |
268 #if defined(__i386__) | |
269 case __NR_socketcall: | |
270 return RestrictSocketcallForNaClNonSfi(sb); | |
271 #endif | |
272 #if defined(__x86_64__) || defined(__arm__) | |
273 case __NR_recvmsg: | |
274 case __NR_sendmsg: | |
275 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
276 case __NR_socketpair: | |
277 return RestrictSocketpairForNaClNonSfi(sb); | |
278 #endif | |
279 | |
280 case __NR_brk: | |
281 // The behavior of brk on Linux is different from other system | |
282 // calls. It does not return errno but the current break on | |
283 // failure. glibc thinks brk failed the return value of brk | |
284 // is lesser than the requested address (i.e., brk(addr) < addr) | |
285 // So, glibc thinks brk succeeded if we return -EPERM and we | |
286 // need to return zero instead. | |
287 return ErrorCode(0); | |
288 | |
289 default: | |
290 if (IsGracefullyDenied(sysno)) | |
291 return ErrorCode(EPERM); | |
292 return sb->Trap(sandbox::CrashSIGSYS_Handler, NULL); | |
293 } | |
294 } | |
295 | |
296 void InitializeBPFSandbox() { | |
297 bool sandbox_is_initialized = content::InitializeSandbox( | |
298 scoped_ptr<sandbox::SandboxBPFPolicy>( | |
299 new nacl::nonsfi::NaClNonSfiBPFSandboxPolicy())); | |
300 CHECK(sandbox_is_initialized) | |
301 << "InitializeBPFSandbox for non-SFI NaCl failed"; | |
302 RunSandboxSanityChecks(); | |
303 } | |
304 | |
305 } // namespace nonsfi | |
306 } // namespace nacl | |
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