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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ | 5 #ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ |
6 #define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ | 6 #define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ |
7 | 7 |
8 #include <stdint.h> | 8 #include <stdint.h> |
9 | 9 |
10 #include "sandbox/sandbox_export.h" | 10 #include "sandbox/sandbox_export.h" |
11 | 11 |
12 namespace sandbox { | 12 namespace sandbox { |
13 | 13 |
14 // This function will return the kernel return value on success and -errno on | |
15 // error on all architectures. | |
14 // We have to make sure that we have a single "magic" return address for | 16 // We have to make sure that we have a single "magic" return address for |
15 // our system calls, which we can check from within a BPF filter. This | 17 // our system calls, which we can check from within a BPF filter. This |
16 // works by writing a little bit of asm() code that a) enters the kernel, and | 18 // works by writing a little bit of asm() code that a) enters the kernel, and |
17 // that also b) can be invoked in a way that computes this return address. | 19 // that also b) can be invoked in a way that computes this return address. |
18 // Passing "nr" as "-1" computes the "magic" return address. Passing any | 20 // Passing "nr" as "-1" computes the "magic" return address. Passing any |
19 // other value invokes the appropriate system call. | 21 // other value invokes the appropriate system call. |
20 SANDBOX_EXPORT intptr_t SandboxSyscall(int nr, | 22 SANDBOX_EXPORT intptr_t SandboxSyscall(int nr, |
21 intptr_t p0, | 23 intptr_t p0, |
22 intptr_t p1, | 24 intptr_t p1, |
23 intptr_t p2, | 25 intptr_t p2, |
24 intptr_t p3, | 26 intptr_t p3, |
25 intptr_t p4, | 27 intptr_t p4, |
26 intptr_t p5); | 28 intptr_t p5); |
27 | 29 |
30 #if defined(__mips__) | |
31 // This function basically does on MIPS what SandboxSyscall() is doing on | |
32 // othere architectures. However, because of specificity of MIPS regarding | |
33 // handelling syscall errors, SandboxSyscall() is made as a wrapper for this | |
34 // function in order for SandboxSyscall() to behave more like on othere | |
jln (very slow on Chromium)
2014/06/13 02:47:36
nit: othere -> other
nedeljko
2014/06/18 13:41:00
Done.
| |
35 // architectures on places where return value from SandboxSyscall() is used | |
36 // directly (like in most tests). | |
37 // The syscall "nr" is called with arguments that are set in an array on which | |
38 // pointer "args" points to and an information weather there is an error or no | |
39 // is returned to SandboxSyscall() by err_stat. | |
40 intptr_t SandboxSyscallRaw(int nr, | |
41 const intptr_t *args, | |
jln (very slow on Chromium)
2014/06/13 02:47:36
Nit: indent (simply use "git cl format").
nedeljko
2014/06/18 13:41:00
Done.
| |
42 intptr_t* err_stat); | |
43 #endif // defined(__mips__) | |
44 | |
28 // System calls can take up to six parameters. Traditionally, glibc | 45 // System calls can take up to six parameters. Traditionally, glibc |
29 // implements this property by using variadic argument lists. This works, but | 46 // implements this property by using variadic argument lists. This works, but |
30 // confuses modern tools such as valgrind, because we are nominally passing | 47 // confuses modern tools such as valgrind, because we are nominally passing |
31 // uninitialized data whenever we call through this function and pass less | 48 // uninitialized data whenever we call through this function and pass less |
32 // than the full six arguments. | 49 // than the full six arguments. |
33 // So, instead, we use C++'s template system to achieve a very similar | 50 // So, instead, we use C++'s template system to achieve a very similar |
34 // effect. C++ automatically sets the unused parameters to zero for us, and | 51 // effect. C++ automatically sets the unused parameters to zero for us, and |
35 // it also does the correct type expansion (e.g. from 32bit to 64bit) where | 52 // it also does the correct type expansion (e.g. from 32bit to 64bit) where |
36 // necessary. | 53 // necessary. |
37 // We have to use C-style cast operators as we want to be able to accept both | 54 // We have to use C-style cast operators as we want to be able to accept both |
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139 __attribute__((always_inline)); | 156 __attribute__((always_inline)); |
140 SANDBOX_EXPORT inline intptr_t SandboxSyscall(int nr) { | 157 SANDBOX_EXPORT inline intptr_t SandboxSyscall(int nr) { |
141 return SandboxSyscall(nr, 0, 0, 0, 0, 0, 0); | 158 return SandboxSyscall(nr, 0, 0, 0, 0, 0, 0); |
142 } | 159 } |
143 | 160 |
144 #endif // Pre-C++11 | 161 #endif // Pre-C++11 |
145 | 162 |
146 } // namespace sandbox | 163 } // namespace sandbox |
147 | 164 |
148 #endif // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ | 165 #endif // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ |
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