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1 // Copyright (c) 2013 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 "chrome/nacl/nacl_sandbox_linux.h" | |
6 | |
7 #include <signal.h> | |
8 #include <sys/ptrace.h> | |
9 | |
10 #include "base/callback.h" | |
11 #include "base/compiler_specific.h" | |
12 #include "base/logging.h" | |
13 #include "build/build_config.h" | |
14 #include "content/public/common/sandbox_init.h" | |
15 #include "sandbox/linux/seccomp-bpf/sandbox_bpf.h" | |
16 #include "sandbox/linux/services/linux_syscalls.h" | |
17 | |
18 using playground2::ErrorCode; | |
19 using playground2::Sandbox; | |
20 | |
21 namespace { | |
22 | |
23 inline bool IsPlatformX86() { | |
24 #if defined(__x86_64__) || defined(__i386__) | |
25 return true; | |
26 #else | |
27 return false; | |
28 #endif | |
29 } | |
30 | |
31 // On ARM and x86_64, System V shared memory calls have each their own system | |
32 // call, while on i386 they are multiplexed. | |
33 #if defined(__x86_64__) || defined(__arm__) | |
34 bool IsSystemVSharedMemory(int sysno) { | |
35 switch (sysno) { | |
36 case __NR_shmat: | |
37 case __NR_shmctl: | |
38 case __NR_shmdt: | |
39 case __NR_shmget: | |
40 return true; | |
41 default: | |
42 return false; | |
43 } | |
44 } | |
45 #endif | |
46 | |
47 #if defined(__i386__) | |
48 // Big system V multiplexing system call. | |
49 bool IsSystemVIpc(int sysno) { | |
50 switch (sysno) { | |
51 case __NR_ipc: | |
52 return true; | |
53 default: | |
54 return false; | |
55 } | |
56 } | |
57 #endif | |
58 | |
59 ErrorCode NaClBpfSandboxPolicy( | |
60 playground2::Sandbox* sb, int sysno, void* aux) { | |
61 const playground2::BpfSandboxPolicyCallback baseline_policy = | |
62 content::GetBpfSandboxBaselinePolicy(); | |
63 switch (sysno) { | |
64 // TODO(jln): NaCl's GDB debug stub uses the following socket system calls, | |
65 // see if it can be restricted a bit. | |
66 #if defined(__x86_64__) || defined(__arm__) | |
67 // transport_common.cc needs this. | |
68 case __NR_accept: | |
69 case __NR_setsockopt: | |
70 #elif defined(__i386__) | |
71 case __NR_socketcall: | |
72 #endif | |
73 // trusted/service_runtime/linux/thread_suspension.c needs sigwait() and is | |
74 // used by NaCl's GDB debug stub. | |
75 case __NR_rt_sigtimedwait: | |
76 #if defined(__i386__) | |
77 // Needed on i386 to set-up the custom segments. | |
78 case __NR_modify_ldt: | |
79 #endif | |
80 // NaClAddrSpaceBeforeAlloc needs prlimit64. | |
81 case __NR_prlimit64: | |
82 // NaCl uses custom signal stacks. | |
83 case __NR_sigaltstack: | |
84 // Below is fairly similar to the policy for a Chromium renderer. | |
85 // TODO(jln): restrict clone(), ioctl() and prctl(). | |
86 case __NR_ioctl: | |
87 #if defined(__i386__) || defined(__x86_64__) | |
88 case __NR_getrlimit: | |
89 #endif | |
90 #if defined(__i386__) || defined(__arm__) | |
91 case __NR_ugetrlimit: | |
92 #endif | |
93 case __NR_pread64: | |
94 case __NR_pwrite64: | |
95 case __NR_sched_get_priority_max: | |
96 case __NR_sched_get_priority_min: | |
97 case __NR_sched_getaffinity: | |
98 case __NR_sched_getparam: | |
99 case __NR_sched_getscheduler: | |
100 case __NR_sched_setscheduler: | |
101 case __NR_setpriority: | |
102 case __NR_sysinfo: | |
103 case __NR_uname: | |
104 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
105 case __NR_ptrace: | |
106 return ErrorCode(EPERM); | |
107 default: | |
108 // TODO(jln): look into getting rid of System V shared memory: | |
109 // platform_qualify/linux/sysv_shm_and_mmap.c makes it a requirement, but | |
110 // it may not be needed in all cases. Chromium renderers don't need | |
111 // System V shared memory on Aura. | |
112 #if defined(__x86_64__) || defined(__arm__) | |
113 if (IsSystemVSharedMemory(sysno)) | |
114 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
115 #elif defined(__i386__) | |
116 if (IsSystemVIpc(sysno)) | |
117 return ErrorCode(ErrorCode::ERR_ALLOWED); | |
118 #endif | |
119 return baseline_policy.Run(sb, sysno, aux); | |
120 } | |
121 NOTREACHED(); | |
122 // GCC wants this. | |
123 return ErrorCode(EPERM); | |
124 } | |
125 | |
126 void RunSandboxSanityChecks() { | |
127 errno = 0; | |
128 // Make a ptrace request with an invalid PID. | |
129 long ptrace_ret = ptrace(PTRACE_PEEKUSER, -1 /* pid */, NULL, NULL); | |
130 CHECK_EQ(-1, ptrace_ret); | |
131 // Without the sandbox on, this ptrace call would ESRCH instead. | |
132 CHECK_EQ(EPERM, errno); | |
133 } | |
134 | |
135 } // namespace | |
136 | |
137 bool InitializeBpfSandbox() { | |
138 // TODO(jln): enable the sandbox on ARM as well. | |
139 if (!IsPlatformX86()) | |
140 return false; | |
141 bool sandbox_is_initialized = | |
142 content::InitializeSandbox(NaClBpfSandboxPolicy); | |
143 if (sandbox_is_initialized) { | |
144 RunSandboxSanityChecks(); | |
145 // TODO(jln): Find a way to fix this. | |
146 // The sandbox' SIGSYS handler trips NaCl, so we disable it. | |
147 // If SIGSYS is triggered it'll now execute the default action | |
148 // (CORE). This will make it hard to track down bugs and sandbox violations. | |
149 CHECK(signal(SIGSYS, SIG_DFL) != SIG_ERR); | |
150 return true; | |
151 } | |
152 return false; | |
153 } | |
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