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Diffstat (limited to 'sandbox/linux/seccomp-bpf/syscall.h')
| -rw-r--r-- | sandbox/linux/seccomp-bpf/syscall.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/sandbox/linux/seccomp-bpf/syscall.h b/sandbox/linux/seccomp-bpf/syscall.h new file mode 100644 index 0000000000..ccfc88dcb3 --- /dev/null +++ b/sandbox/linux/seccomp-bpf/syscall.h @@ -0,0 +1,166 @@ +// Copyright (c) 2012 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ +#define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ + +#include <signal.h> +#include <stdint.h> + +#include "base/macros.h" +#include "sandbox/linux/system_headers/linux_signal.h" +#include "sandbox/sandbox_export.h" + +namespace sandbox { + +// This purely static class can be used to perform system calls with some +// low-level control. +class SANDBOX_EXPORT Syscall { + public: + // InvalidCall() invokes Call() with a platform-appropriate syscall + // number that is guaranteed to not be implemented (i.e., normally + // returns -ENOSYS). + // This is primarily meant to be useful for writing sandbox policy + // unit tests. + static intptr_t InvalidCall(); + + // System calls can take up to six parameters (up to eight on some + // architectures). Traditionally, glibc + // implements this property by using variadic argument lists. This works, but + // confuses modern tools such as valgrind, because we are nominally passing + // uninitialized data whenever we call through this function and pass less + // than the full six arguments. + // So, instead, we use C++'s template system to achieve a very similar + // effect. C++ automatically sets the unused parameters to zero for us, and + // it also does the correct type expansion (e.g. from 32bit to 64bit) where + // necessary. + // We have to use C-style cast operators as we want to be able to accept both + // integer and pointer types. + template <class T0, + class T1, + class T2, + class T3, + class T4, + class T5, + class T6, + class T7> + static inline intptr_t + Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6, T7 p7) { + return Call(nr, + (intptr_t)p0, + (intptr_t)p1, + (intptr_t)p2, + (intptr_t)p3, + (intptr_t)p4, + (intptr_t)p5, + (intptr_t)p6, + (intptr_t)p7); + } + + template <class T0, + class T1, + class T2, + class T3, + class T4, + class T5, + class T6> + static inline intptr_t + Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6) { + return Call(nr, + (intptr_t)p0, + (intptr_t)p1, + (intptr_t)p2, + (intptr_t)p3, + (intptr_t)p4, + (intptr_t)p5, + (intptr_t)p6, + 0); + } + + template <class T0, class T1, class T2, class T3, class T4, class T5> + static inline intptr_t + Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5) { + return Call(nr, + (intptr_t)p0, + (intptr_t)p1, + (intptr_t)p2, + (intptr_t)p3, + (intptr_t)p4, + (intptr_t)p5, + 0, + 0); + } + + template <class T0, class T1, class T2, class T3, class T4> + static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4) { + return Call(nr, p0, p1, p2, p3, p4, 0, 0, 0); + } + + template <class T0, class T1, class T2, class T3> + static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3) { + return Call(nr, p0, p1, p2, p3, 0, 0, 0, 0); + } + + template <class T0, class T1, class T2> + static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2) { + return Call(nr, p0, p1, p2, 0, 0, 0, 0, 0); + } + + template <class T0, class T1> + static inline intptr_t Call(int nr, T0 p0, T1 p1) { + return Call(nr, p0, p1, 0, 0, 0, 0, 0, 0); + } + + template <class T0> + static inline intptr_t Call(int nr, T0 p0) { + return Call(nr, p0, 0, 0, 0, 0, 0, 0, 0); + } + + static inline intptr_t Call(int nr) { + return Call(nr, 0, 0, 0, 0, 0, 0, 0, 0); + } + + // Set the registers in |ctx| to match what they would be after a system call + // returning |ret_val|. |ret_val| must follow the Syscall::Call() convention + // of being -errno on errors. + static void PutValueInUcontext(intptr_t ret_val, ucontext_t* ctx); + + private: + // This performs system call |nr| with the arguments p0 to p7 from a constant + // userland address, which is for instance observable by seccomp-bpf filters. + // The constant userland address from which these system calls are made will + // be returned if |nr| is passed as -1. + // On error, this function will return a value between -1 and -4095 which + // should be interpreted as -errno. + static intptr_t Call(int nr, + intptr_t p0, + intptr_t p1, + intptr_t p2, + intptr_t p3, + intptr_t p4, + intptr_t p5, + intptr_t p6, + intptr_t p7); + +#if defined(__mips__) + // This function basically does on MIPS what SandboxSyscall() is doing on + // other architectures. However, because of specificity of MIPS regarding + // handling syscall errors, SandboxSyscall() is made as a wrapper for this + // function in order for SandboxSyscall() to behave more like on other + // architectures on places where return value from SandboxSyscall() is used + // directly (like in most tests). + // The syscall "nr" is called with arguments that are set in an array on which + // pointer "args" points to and an information weather there is an error or no + // is returned to SandboxSyscall() by err_stat. + static intptr_t SandboxSyscallRaw(int nr, + const intptr_t* args, + intptr_t* err_stat); +#endif // defined(__mips__) + + DISALLOW_IMPLICIT_CONSTRUCTORS(Syscall); +}; + +} // namespace sandbox + +#endif // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__ |